Recent developments in the growth of Rm3(bo3)4 crystals for science and modern applications

Prog. Crystal Growth and Charact. Vol. 31, pp. 279-312, 19g5 Copyright © lg96 Elsevier Science Lid Printed in Great Britain. All rights reserved 0960-8974195$29.00

Pergamon

RECENT DEVELOPMENTS IN THE GROWTH OF RM3(BO3) 4 CRYSTALS FOR SCIENCE AND MODERN APPLICATIONS N. I. L e o n y u k Department of Crystallography and Crystal Chemistry, Geology Faculty, Moscow State University, 119899 Moscow, Russia

CONTENTS

i. Introduction

2. Crystal Growth 2.1.

Selection

of Fluxes

2.2. Spontaneous Crystallisation 2.3. Top-seeded Solution Growth 2.4. Czochralski Growth

3. Characterization 3.1. Chemical Analysis 3.2. Crystal Morphology 3.3

Optical Characteristics

4. Conclusion and Outlook

Acknowledgements

References 279

N.I.L~n~k

280

1.INTRODUCTION

More RAI-

than

three

decades

and RCr-borates,

Yb and

indicate m o r e where

R=Y,

in

fluxes.

R=Sm

or Gd

At present,

a

than six d o z e n c o m p o u n d s

La-Lu,

characterized the

by

In or Bi,

and

growth

studied.

and

Ballman Nd,

Eu,

synthesized Gd,

flux m e t h o d

Sc,

Cr,

crystals.

characterization

Fe,

Most

Dy,

Ho,

Er,

K2SO4-3MoO 3

f o r m u l a RM3(B03) 4

Ga.

The

of these

majority

the

of

family

large

of

crystals were

for c o n v e n i e n c e this

twelve

in the l i t e r a t u r e

w i t h a general

and M=AI,

Therefore,

Tb,

using

the date a v a i l a b l e

them have b e e n o b t a i n e d as single

on

1962

RAI3(B03) 4 w i t h R=Y,

RCr3(B03) 4 w h e r e

and P b F 2 - 3 B 2 0 3

ago,

investigation of

double

this

period

borates can be c o n s i d e r e d to o c c u r in three stages. The

first

some RGasolid

and

state

spontaneous

quality

RFe-borates

of

cases,

also

For

the

and

to

of

for about

ten years.

have

synthesized,

other

been

above

K2SO4-3Mo03

crystallization

luminescence led

continued

reactions.

the m a j o r i t y

fluxes

stage

of

studies.

mentioned

and

the

compounds

However,

the n o n - r e p r o d u c i b i l i t y microcrystalline

of

solvent

for

the

crystal

growth

but

and

fluxes which

were were

high

the

experimental and

a

the

through

used

of

in for

used

volatility

Consequently, of

only

RCr-borates

the

materials

s t o i c h i o m e t r y of the r e s u l t a n t products. optimum

RAI-

PbF2-3B203

these

Within

for these

results,

deviation

bad from

the search of the

given

materials

was

a

h i g h - p r i o r i t y task. The s e c o n d stage b e g a n in the early s e v e n t i e s w h e n a more effective and best

convenient

solvents

technological

kinetic

study

of

flux a

for was

(YAB)

RAI3(B03) 4 b o r a t e s

discovered

K2SO4-3MoO 3

b a s e d on the K2Mo3010 melt. of YAI3(B03) 4

the

melt

at

as

a

result

800-ii00°C

For the first time

were

proposed.

of [2].

a

The

volatility

This

flux

is

it was u s e d for the T S S G

crystals with a good optical q u a l i t y

[3].

Rece~deve~pme~sinthegm~h ~ RM3(BOs)4cw~als Subsequently,

the m o n o p h a s e

NdAI3(B03) 4

(NAB),

RFe-borates

have been

component

systems

in complex (YFB)

supersaturation GAB

for

single

first

As

a

crystals fluxed

of

these

using

result,

were

grown

based

on

was

wide

investigated

ranges NAB,

of

relative

(Nd,Y)AI3(BO3) 4

top-seeded

the

some of the

of YAB and YFe3(B03) 4

YAB,

by

and

of YAB,

and pseudo-five-

borates

kinetics

time

main

melts

(YGB),

for m a n y p s e u d o - f o u r

Crystallization

solution

growth

K2Mo3OI0-B203-R203

systems

.

In 1974 a second harmonic investigated a

of the c r y s t a l l i z a t i o n

YGa3(BO3) 4

solubility

the

[8,9].

from the m o d i f i e d [10]

the

[4-7].

studied

(GAB),

established

and

fluxes

were

(NYAB),

GdAI3(BO3) 4

regions

281

[ii] . S i m u l t a n e o u s l y

promising

quenching laser

generation

class

that

action

the in

of

laser

NAB

crystals

crystals

authors

[15] d e s c r i b e d

efficient

lasers.

In

the

stimulated observed

1981

for

radiation

in NYAB

the authors materials

traditional

the

in the RAI3(BO3) 4 crystals

was

time

the

In

five

same

ran was 1989

the

Finally

in

pumping

in NYAB crystals

CW

In the eighties synthesized the NdAI,

[20].

Czochralski SmAI-,

with a lower

time

fabricated green

[13,14].

CW the

was

using

generation

of

generation

was

dye

as

rod

3.2

crystal

mm

by

generated

a pumping doubling

in diameter

the

authors

using

and [18].

laser

diode

[19].

the

technique.

time

authors Also,

EuAI- GdAl-borates, symmetry,

a NAB

light

for the first

Later,

Later Also,

laser s e l f - f r e q u e n c y

a laser

from

laser

luminescence

example).

simultaneous

years,

in NYAB

23.7

for

demonstrated

[17] d e m o n s t r a t e d

length

weaker

of Nd 3+ ions and its second harmonic [16].

that NAB are

cross p u m p i n g of Nd 3+ by Cr 3+ in NAB:Cr

first

crystals

At

having (Nd:YAG

light source the authors crystal.

[12] r e p o r t e d

was

it

the L a - s c a n d o b o r a t e s

[21] obtained has

been

the

LSB

established

(LSB)

crystals that

and LSB form h i g h - t e m p e r a t u r e

C2/c or C2 space group

[22].

These

were by

PrAI-,

polytypes

two stages

of

282

N.I.L~n~k

investigations crystals

on

the

(1962-1991)

In recent years, of p u b l i c a t i o n s

growth

since

other ions.

In particular,

efficiency

[24],

medium

with

a

purpose

of

the

growth,

optical

characterization

the early n i n e t i e s RM-borate

Cr3+-doped

present

RM-borate

[23].

there have b e e n a number

crystals

RAI-

and

which

review

is

characterization

d o p e d w i t h Nd 3+,

to

and

related

are

tunability

discuss

2. C R Y S T A L

within

RSc-borates

includes

and p r o v i d e an u p d a t e on the above review

above,

the

Cr 3+ and

the N d 3 + : L S B can be a laser crystal w i t h high

double-function

As m e n t i o n e d

of

have b e e n d e s c r i b e d in the review

on v a r i o u s

and

and

current studies

a

new

[25,26].

progress of

laser

these

The

in

the

crystals

[23].

GROWTH

the past

five years

the m a i n

attention

has b e e n p a i d to the g r o w t h of RAI3(B03) 4 and RSc3(B03) 4 crystals.

Also,

there are some data on single crystals of solid s o l u t i o n s b a s e d on other double

borates

of

high-temperature

this

solutions

by C z o c h r a l s k i

technique

2.1.

of Fluxes

Selection

The m a j o r i t y RSc-borates

were

[25,26,29-38], authors

family

of

R(AI,Ga)-,

on

proposed

for well

[27,28] the

g r o w t h of NYAB single crystals. Table i.

These

crystals YSc-

were

and

grown

from

GdSc-boartes)

or

(RSc-borates).

Bi203-B203

[ 4 1 ] have

(RAI-,

solvents

based

[27-29].

crystal known or

growth

fluxes:

Ba0-B203

Na2B407

as

a

a

of

RAl-and

modified

some

K2Mo3010

[31,39,40] . Also, new

solvent

of

for

All of these solvents are r e p r e s e n t e d

the the in

283

Rece~deve~pmemsinthegro~h~ RM3(BO3)4cw~als Table

i. The appropriate solvents for some doped RAI-, RSc- and (R, Bi) (Ai,Ga)-borates

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =

Borate

I

Flux,

wt.%

I Reference

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =

Cr3+ :YA13 (B03) 4

K2Mo3010

[25,29]

97K2Mo3010-3B203

[26]

89.5K2MO3010-0.7(Y,Nd)203-9.8B203 93.8 K2Mo3010 - 6.2 B203 Na2B407

[32-35]

Nd :GdAI3 (B03) 4

K2Mo3010

[36]

(Y, Gd) A13 (BO 3 ) 4

92.1K2Mo3010-7.9B203

[30,35]

Cr 3+ :Y (Ga, AI) 3 (B03) 4

K2Mo3010

[29]

Cr3+ :GdAI 3 (B03) 4

K2Mo3010-B203

[38]

Cr 3+ :RSc (BO 3) 4 (R=Y or Gd)

K2Mo3010-B203

[38]

(R, Bi) A13 (B03) 4 were R=Er or Yb (doped with Si 4+, Ge 4+, Ti 4+, V 5+, Cr 3+, Mn 4+)

Bi203-B203-Li203

[27]

(R,Bi) (AI,Ge)3(B03)4

Bi203-B203

[28]

(Y, Nd) A13 (BO 3 ) 4

The achieving the

volatility

pure

The

which

the

the

the

K2Mo3010

[26].

solubility,

of

melt

can

reduction

be

This

solution

by

a

problem

fluxes

high-temperature

from pure p o t a s s i u m to an earlier

paper

in

of

lower than rates temperature

the

range

ref.

a

very

for

the

in Fig.l

obtained

[26,38]).

The

a

decrease

solutions [38].

data

the the

B203

based

However,

on the

greater

[42]. rates

order

by m o d i f y i n g

to

increasing

concentrated

melts

one

in

Consequently,

evaporation

are

for

of B203

is substantially

trimolybdate the

optimum

significantly

solutions

950-i150°C

for the solutions (see

rate

[42],

in

is

excess

10-40°C.

with

is shown

flux

small

resulting

in evaporation

K2Mo3010

of these

According

same

to

of such flux will be reduced without

than evaporation

K2Mo3010

B203

of YAB crystals

enhances

and modified

volatility

3 wt.%

temperature

viscosity

solution.

of

the growth

solution

saturation

the

addition

[37] [41]

of

of pure

magnitude

the flux at the

available

in

Table

2

284

N.I. Leon~k

indicates that p o t a s s i u m t r i m o l y b d a t e melt p r o b a b l y d e c o m p o s e s

according

to the equation: 2K2Mo3010

= K20 + 2MoO 3 + K2Mo4013.

The r e l a t i v e v o l a t i l i t i e s general

evaporation

evaporation

rates

rate U and from chemical

can

v a p o u r pressures:

of K20 and MoO 3 were d e t e r m i n e d

be

P(K20)

easily

from the

analysis

(see Table

into

and

transformed

K20

MoO 3 partial

and P(Mo03).

•

.

.

,

i

1120 a: Y A B - K . M o . O b: Y ~ ~

.

~

o

~

oo 1080

E ~

lO4O

1000 9

21

23

27

25

YAI3(BO3)4(v~.%) Fig.l.

The e v a p o r a t i o n rate versus the t e m p e r a t u r e the K 2 M o 3 0 1 0 - c o n t a i n i n g solutions [38].

for

Table 2. The e v a p o r a t i o n rates U (xl0-4g-cm-2.h -I) and chemical analysis of the K 2 M o 3 0 1 0 melt a f t e r i00 hours e v a p o r a t i o n in the range of 9 0 0 - I 1 5 0 o c [42]

~

=

=

=

=

=

~

=

~

=

=

=

=

=

=

=

~

=

=

=

=

=

=

=

~

=

=

=

=

=

=

=

~

=

=

=

=

=

~

=

=

Chemical

=

=

=

=

=

=

=

~

=

=

analysis,

=

=

=

=

wt%.

. . . . . . . . . . . . . . . . . . . . . . . . . . . .

T,°C =

=

=

=

=

=

=

=

U =

=

=

=

=

=

=

=

=

25 900 i000 ii00 1150 =

=

=

=

=

=

=

K20 =

=

=

=

=

=

=

=

=

=

=

=

=

=

0 1.3 3.8 9.2 12.4 =

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

I =

=

=

=

=

=

=

=

=

MoO3 =

=

=

=

=

=

18.5 18.3 18.1 17.6 17.4 =

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

81.5 81.7 81.9 82.4 82.6 =

=

=

=

=

=

=

=

=

=

=

=

=

2) The

=

=

=

=

=

Rece~deve~pme~sinthegm~h~ RM3(BO3)4cwsmls Using pressure

the (ln

evaporation kJ/mole

P)

on

K20

the exponential

as

a

the

inverse

Mo03,

have

been

of

of

the

the

(T,K),

A

logarithm the

estimated

respectively.

function

relationship

dependence temperature

energies

and

rate

for

the

activation

for

evaporation

equation

285

temperature

values

to be

graph

of

120 the

rather

at e l e v a t e d t e m p e r a t u r e s

partial of

the

and

155

K2Mo3010

differs

from

(Fig.2) .

-e u

2,0

i

I

Fig.2.

More therefore these is

to

be

inhibited

during

although The increase

octahedral the

flux

increases

expected by

i

8,0

8J ~0 q T

The l o g a r i t h m of K2Mo3010 e v a p o r a t i o n rate versus the inverse temperature (T,K) .

stable

complexes

i

~,~

~o

that

decreasing

evaporation at higher

the the

one gets a consequent addition

of

3

polymolybdate

wt.%

complexes

process.

temperatures.

origin

of

solvent

The

form

rate

of

On the other hand,

it

polymolybdate concentration

complexes in

in evaporation.

B203

the

in s o l u b i l i t y by 1-2 wt.% YAB

probably

formation

increase to

(igU)

K2Mo3010

the

flux

(Fig.3) . The authors

can

be

solutions,

leads

to

an

in reference

286

N.I.L~n~k

[37] have u s e d

the

flux

containing

the K2Mo3010 for the g r o w t h 10-20 P. This

[31].

of

YAB

inside

quality.

The

substantially with

solvents

(more

the

excess

B203

T h e i r v i s c o s i t y was

than

at t e m p e r a t u r e s

K2Mo3010 20 wt.%)

higher

as inclusions,

single

phase

region

with

for some of

a decrease of Y203

seem m o r e

and B203

suitable

and

Li2B407

flux were

using found

the

of YAB

solution

of YAB up up

to to

crystal

is e x p a n d e d 17 wt.% 3-4

and

a new

flux c o m p o s i t i o n

been

developed

consisting

which

yields

size and q u a l i t y to the R A l - a n a l o g u e s

[38].

15

o

10

Q

' 1000

, 1100

1 !00

Ternperature(°C) Fig.3.

8-10

crystals.

a: Y A B - K . M o . O I ^ ' b:' A 8 - K 2 M 0 3 0 1 0 - 8 2 0 3

0 9(30

and

the solvents w i t h a small excess of

for the g r o w t h of R A l - b o r a t e

has

useless

r-

b

about

A I 5 B O 9 is

strongly deteriorating

content

to

be

to

2O

E

to

considerable

I100oc n e e d l e - l i k e

crystallization

in the

the RSc-borates,

K2Mo3OI0

of

For this reason,

crystals of e q u i v a l e n t

25

on

seeds

R203 and B203

of

based

NYAB

respectively.

mixture

crystals.

these

the a d d i t i o n

wt.%,

As

and

In this case,

formed

of N Y A B

(=6.2 wt.%)

flux can d i s s o l v e m o r e than 20 wt.% of N Y A B b e l o w ll00oc.

However, amounts

0.5 mol%

S o l u b i l i t y of YAB in a flux c o n t a i n i n g K2Mo3OI0(a) a m i x u r e of K2Mo3010 3 wt.% B203 (b) [26,38].

and

of a these

R~e~deve~prne~sinthegm~h ~ RM3(BO3)4cw~als As opposed to solvents based on a m o d i f i e d fluxes For

were

also

instance,

used

well

crystallization

known

of

Nd 3+

[27,28].

containind only

fluxes

the

crystal

fluxes

based

rare-earth

other h u n t i t e - b o r a t e s and

for

in

authors

order

non-stoichiometric

to

of

In

elements were used for the crystal Single

crystals

solution growth Finally, used

from BaB407

of NYAB

With

respect

dissolving

crystallization of 21 mol%

this

linear.

The

concentration yttrium

(near

48 mol%

its

right

have

been

various

used and

for some

Cr 3+, Mn 4+,

selected

huntite-type

again

were

the

Bi203

structure

amounts

of

using dopant

grown

by

top-seeded

[40] . as a potential [41].

It was

the

Na2B407

solvent

shown

does

melt

to be

that

not

extends

compounds

sodium

exceed

I00

the

right

boundary)

side

very

high

spontaneous

from a solute

concentration

respectively

of

the

that m a x i m u m

corresponds

a

The

crystallize

dependence shows

has

temperatures.

at 920°C and ll00°C,

in Fig.4a

Therefore,

borates.

Ge 4+, Ti 4+, V 5+,

its v i s c o s i t y

moderate

in this solution

oxide.

region

at

temperature

The d i a g r a m

double

(900-II00°C) .

YBO 3 and AI4B209

region.

and

region of YAl-borate

to about

The Na2B407,

NAB

crystals

ref.[41],

ability

the other

growth of these borates.

examined

flux

used

to

was

single

is an efficient

cP at the t e m p e r a t u r e

the

fluxed melts

melt

flux,

(R,Bi) (AI,Ga)3(BO3) 4

addition

monoclinic

a Na2B407

for growth

tetraborate

of

these

ref.[27.28]

attain

melts.

of

on Bi203-B203

doped with Li +, Si4+, The

K2Mo3010

growth

borates

287

in the

fields

solubility

is

near

almost

of the YAB e q u i l i b r i u m

to a m i n i m u m of

(Fig.4a).

the

concentration

YAB

is more

preferable

for

double

of

crystallization

to

growth

of

YAB

crystals. The

crystallization

narrow

if the y t t r i u m

region

is shifting

with a n e o d y m i u m the

regions

is replaced by n e o d y m i u m

to the

right

concentration

stoichiometric

the

line.

Such

and down

and

(Fig.4b).

of more than 50at.%, substitution

has

borate

are

gradually

simultaneously, In the

case

this shift

significantly

this

of NYAB

is beyond no

effect

288

N.I. Leon~k

on

the

temperature

aggressive volatile

range

towards

of

NYAB

platinum

crucibles,

These

they

solutions

are

are

practically

not non-

at 900-ii00oc.

NazB407 /% \\ / V~

2 0 Z

O" , \ ~ .

.ol ,o/ / so/ ~a~

....... .....

950°C 1000°C loso°c

.......

,,oo°c

\\

20/

4.0/

,~.-.~,~. \,o

,g

,(-,), \,o ,,,o.h[ \ \

\5o

l'

NdAI3(BO3)4 regl°n region NdAI3(BO3)4

/

1/4 YAIs(BO3)4

\ 20

~

/ \50 5o/ ~.,

\

YAI3(BO3) Y A I 3 ( 4 region ~

YBO3

Fig.4.

/ ~k

/

"/.\\ \.0, ,

_

Na~407 A

20

~,o. ~....'\ k

l

2.2.

existence.

A I B O 3 NdBO3

1/4 NdAIs(BO3)4

AIBO3

C o n c e n t r a t i o n regions and temperatures of YAB and NAB spontaneous c r y s t a l l i z a t i o n in the N a 2 B 4 0 7 - Y B O 3 - A I B O 3 (a) and N a 2 B 4 0 7 - N d B O 3 - A I B O 3 (b) p s e u d o - t e r n a r y systems [41]

Spontaneous

Crystallization

Three kinds

of the double borates

have been obtained by spontaneous

crystallization. Crystals with

14

Fig.4

different

[41].

diameter of the

of YI_xNdxAI3(B03) 4

The

solutions

initial

ratio.

15 g, d e p e n d i n g held

saturation

components

for

The

total

hours

temperature

at (by

data

prepared

from

in

amount

H3B03, of

a

temperature

50-I00OC).

given

of previous

higher

Thereafter,

with

between

mixture than the

in a

mixtures

and AI203)

varied

starting

solution

crucibles

Y203 , Nd203

A

from

diagrams

platinum

each melt

composition.

grown

the

of 30 mm by m e l t i n g

(Na2C03,

on the melt 8-16

using

were

of 20 m m and a height

appropriate

and

compositions

(0 < x < I) were

in an 10 and

was melted

the

expected

homogenized

Rece~deve~pme~sinthegm~h ~ RMs(BO3)4cw~als solutions

were

nucleation

of

diameter) with

cooled crystals

contacted

a rate

of

the furnace,

lOC/h

the

for

of

having

oxides

of

up

fluxes

was

during treatment

=

=

=

=

=

=

~

=

=

Melts .

.

.

.

.

.

=

=

=

=

.

~

=

=

=

=

.

.

.

.

.

.

Total .

.

.

.

.

=

=

=

The

=

=

=

=

.

.

.

.

.

.

.

.

.

.

.

.

=

(10 m m

was

was

in

cooled

taken

out

of

For

(R=Yb, been

of

with

and from

crystals,

AI203

lid.

a The

on the kind of

Starting melt c o m p o s i t i o n s

profile

Ho

obtained

the p r e p a r a t i o n crucible

Er,

and all t e m p e r a t u r e

are given parameters

=

=

=

=

=

=

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

=

=. = .=

.

=

=

~

=

=

=

.

.

=

=. = .=

.

.

.

.

.

.

.

.

.

] 4.72 ] 4.61 0

=

=

=

=

=

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

]12.10 .

.

.

.

5.74 5.63 0

.

.

.

~

=

=

=

[28]

~

=

=

=

3-1 .

1.14 0 2.55 0 0 0 8.41

]ii.94 .

=

.....

1.12 0 2.53 0 0 0 8.29 .

=

2-2

0

]12.21 .

=

2-1

(mol%)

.

.

.

.

.

.

.

.

.

.

4.68 4.57 0

=

=

~

=

=

=

=

=

=

=

3-3

.

=

=

=

=

=

3-4

i ....

0

1.10 0 2.46 0 0 0.05 8.02

0 0 3.69 0 0 0 8.23

1.10 2.25 0 0 0 0.07 8.29

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

]ii.92 .

.

.

.

7.14 7 ii 0

.

.

.

.

.

.

.

.

.

=

i .....

]ii.63 .

=

3-2

.

5.78 5 61 0 27

.

.

.

.

.

.

1.07 0 2.29 0 0 0 8.08

.

[ii.71 .

.

.

]14.24

.

] 5.90 ] 5 67 0

5.60 5.52 0.12

TiiT;;-iIiT;i-TIiTi;-TiiTi;-iI;Tii-iii];i-iiiTIi-Yi;T;i

.

=

=

0 0 0 3.73 0 0 8.48

] 4.92 ] 4 81 0

.

=

.

=

....

112.05

AI203 Ga203 Cr203

i1;1

=

.

0 0 0 1.76 1.74 0 8.55

.

=

=

Yb203 Tm203 Er203 Ho203 Sm203 Nd203 Bi203 .

disc

ranged from 30-130 g, d e p e n d i n g

1-2

0

.

disc

After

are shown in Fig.5 and Table 4, respectively.

sc2o3

.

hours.

solution

mm 3 have

in p l a t i n u m

temperature

I-i

.

the

this

2x2x2

3. S t a r t i n g melt compositions

=

2

platinum

surface Then,

to

[28].

placed

in Table 3. A typical

=

every

(R,Bi))AI,Ga)3(BO3) 4

crucible used and melt composition.

=

at

(60 rpm)

hours.

size

total amount of each melt

Table

10oc

solution

8-16

crystals

in Bi203-B203

mixture

of

and cooled to room temperature.

combinations)

solution

steps

on a rotating

with

Bi-containing its

in

289

=

=

=

same

crystallization

=

=

=

=

=

=

=

=

=

=

=

=

=

=

procedure of

=

=

=

=

=

=

=

=

=

=

has

YbAI3(B03) 4

and

=

=

=

=

=

been

=

=

=

=

=

=

=

used

=

=

=

=

=

=

=

=

=

for

ErAI3(B03) 4 doped

=

=

=

=

=

=

=

the

spontaneous

with

Si 4+,

Ge 4+,

200

N.I. Loon~k

Ti 4+, V 5+,

C r 3 + , a n d Mn 4+ and w i t h

size of some of t h e m up to 3x4x16 m m 3

(Tables 5 and 6) [27] .

~t(l)

t/~

t(3)

~= T(2)t" ........t'............ k,.

t(4)

t(5)

7 Rooln temperature

\. r

Time Fig.5.

S c h e m a t i c t e m p e r a t u r e p r o f i l e d u r i n g crystal growth. (Actual values of t e m p e r a t u r e and time are p r e s e n t e d in Table 4) [28].

Table 4. T e m p e r a t u r e (oc) and time (h) p a r a m e t e r s of crystal g r o w t h run [28]

compositions

1

i-2

1

2-2

I

3-3,

3-4

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =

T(1) T(2) T(3) t(1) t(2) t(3) t(4) t(5)

GdSc3(B03) 4

1200 I000 500 9.0 4.0 1.0 56.0 4.0

crystals

with

obtained using a K2Mo3010-Li2B407 25

cm 3

[38].

The

fluxed m e l t

was

the t e m p e r a t u r e range 1330-I100oc.

1200-1250 1050 600 9.0 7.0 0.5 96.0 5.0

a

size

about

1300 1100 650 I0.0 4.0 0.5 74.0 10.0

10x6xl

mm 3

have

been

flux in P t - c r u c i b l e w i t h a c a p a c i t y of cooled

at

the

rate

of

2-3°C/h

within

Recent developments in the growth of RM3(B03) 4 crystals Table

5. Melt c o m p o s i t i o n s (mol%), c o n c e n t r a t i o n of o x i d e s w h i c h f o r m e d h u n t i t e C (mol%) and p r o d u c t i v i t y of m e l t s P (wt%) [27]

Er203 Nd203 Bi203 Li20 AI203 SiO 2 GeO 2 TiO 2 V205 Cr203 Mn203 B203 C(mol%) P (wt%)

Table

0 0 9.5 0 16.0 0 0 0 0 0.i 0 69.1 43 32

5.6 0.I 10.0 0 16.7 0 0 0 0 0 0 67.6 44 36

0 0 8.2 0.2 18.6 0 0.8 0 0 1.0 0 66.0 52 41

0 0 7.1 0.2 23.2 0 0 0 0 0 0.8 i61.1 64 54

0 0 6.2 0.3 26.1 0.8 0 0 0 0 0 57.9 72 58

0 0 3.9 0.4 29.4 0 0 0.8 0 0 0 55.7 81 70

6. Crystal g r o w t h p a r a m e t e r s : T-temperature (°C); t - d u r a t i o n

(h)

0 0 0 14.6 25.1 0 0 0 0.6 0 0 51.3 68 18

0 0 2.9 0.7 31.5 0 0 1.0 0 0 0 53.4 85 71

0 0 1.9 0.4 33.4 1.0 0 0 0 0 0 52.2 90 76

0 0 1.0 0.4 35.6 0 0.8 0 0 0 0 50.4 96 77

[27]

composition

8-2,8-3 9-1,9-2,9-3, 9-4 10-1,10-2, 10-3

1300 1320

1160 1200

600 600

10.0 I0.0

10.0 8.0

0.5 0.5

95.0 137.0

10.0 i0.0

1340

1250

500

10.0

8.0

0.5

112.0

i0.0

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =

2.3. T o p - s e e d e d S o l u t i o n G r o w t h

Several and

BaO-B203

within

last

20 wt.%:80

fluxes were

such

as

used

to

five years.

The

wt.%

- 22

K2Mo3010, grow

the

starting

wt.%:78

wt.%

K2Mo3010-B203, RM3(B03) 4 ratio

K2Mo3010-B203-R203

crystals

of solute

by

TSSG

to solvent

(for K 2 M O 3 O l 0 - c o n t a i n i n g

method

was

fluxes)

from to

292

N.I.L~n~k

56 wt.%:44wt.%

(for BaB407

flux).

The

comparison

of growth

parameters

for TSSG of some pure and doped RM3(B03) 4 (R = Y,Nd,Gd and M = AI,Sc,Ga) single crystals is given in Table 7.

Table 7. Experimental parameters for TSSG of some RM3(B03) 4 single crystals =

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

Flux and its ratio to solute, wt.% .................................

Crystal

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

YA13(BO3) 4 (doped with 0.2 at.% Cr 3+)

YAI3 (BO3)4 [doped with 0.2 or 0.5 at.% Cr 3+ )

YAI3 (BO3)4 (doped with 6-8 at.% Nd 3+

Y (Ga,AI) 3 (BO3)4 [doped with 0.2 or 0.5 at.% Cr 3+ )

(Nd,Y)AI3(BO3) 4 (Nd:5-10 at.%)

GdAI3(BO3) 4

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

=

Coolling i(n g - I Growth Growth e, I range rate, ( d °C/d = = = = = =

= = = = = = = = = = =

=

=

=

=

=

=

=

=

=

=

=

=

=

=

Crystal 3 Crystal I size,mm = = = = = = = = = = =

RefefeRerence

= = = = = =

97K2Mo3010-3B203 (78 wt.%)

2-4

I

~T=II0°C

K2Mo3010 (80 wt.%

3

1

weeks 3-4

93.8K2Mo3OI06.2B203 (8o wt.%)

2 - 0 1 A T = 421 3 ° Cdays ,

K2Mo3010 (80 wt.%)

3

89.5K2Mo30100.7(Nd,Y) 2039.8B203 (80 wt.%)

°ss 61450c iT1s i 12x12x2° i c35

K2Mo3OI0-B203

2-4

AT=I60oc

27x9x5

[38]

K2Mo3010 (80wt.%)

2-3

40-50 days

Up to 20mm

[36]

K2Mo3010Li2B407

2-4

AT=I80oc

28x26x19

[38]

BaB407 (44 wt.%)

2.4

AT=33oc

9x7x19

[40]

1 I

3-4 weeks

I 12x16x22

I I] [ I

I

[26]

12x12x101129]

i 16x16x18

10x9.5x7

I[

37]

[29]

days

(doped with Cr J+ )

GdAI3(B03) 4 (doped with Nd ~+ )

YSc3(B03) 4 (doped with Cr j+ )

NdAI3 (BO3)4

Recemdeve~pmemsinthegro~h ~ RM3(BO3)4cw~als Usually, height

of

normal

and

platinum

50 m m were radial

used

The

Eurotherm

temperature

materials

was

temperature stirring

temperature

of

a

of

these

gradients

could

diameter

be

at

a

period

70-120°C

temperature

of

the

of

12

higher

hour

an

50-65

with

above

for

and

38].

were

0.1°C

mixture

stirring

equilibrium

29,

within

The

50°C

[26,

mm

solutions

controlled

some

of

crystal

controller/programmer.

kept

for

with

for T S S G

temperature

l-2°C/cm.

temperature

crucibles

293

of

the

The

about by

an

starting saturation

[29],

30-40

a

or

hours

at

a

without

[36,37,40]. The s a t u r a t i o n t e m p e r a t u r e s were d e t e r m i n e d exactly

by the r e p e a t e d s e e d i n g method.

The chosen seed crystal was b r o u g h t

contact w i t h the

s o l u t i o n at a t e m p e r a t u r e

temperature

dissolve

to

the

outer

15-20oc above

surface

of

t e m p e r a t u r e was l o w e r e d to the s a t u r a t i o n point

the

the

into

saturation

seed,

and

the

for 0.5-2.0 hours.

The q u a l i t y of the g r o w i n g c r y s t a l s depends on seed o r i e n t a t i o n and the s o l u t i o n flow. from the <001>

The best result was found for the N Y A B c r y s t a l s grown

seed

[37]

and

for the NAB

in the <201> or <100> d i r e c t i o n at a rate of 4-6 rpm with

reversal

rpm of

crystals were p u l l e d

[26,36,38],

crystals

[40]. The g r o w i n g 15 rpm

[38],

the r a t a t i o n d i r e c t i o n

g r o w n by

the

seeding

c r y s t a l s were

rotated

30-40

every

60

rpm s

[37,40], [29].

The

or 60 grown

from the s o l u t i o n and then cooled d o w n to the r o o m

t e m p e r a t u r e at rates 30-50°C/h.

2.4.

Czochralski

Single LaSc3(BO3)4,

Growth

crystals NdSc3(B03) 4

20

mm

and

g r o w n by the C z o c h r a l s k i m e t h o d

in

diameter

their

solid

and

75

solutions

mm were

in

length

of

successfully

[21,24]. The p u l l i n g speed was

1-3 mm/h.

294

N IL~n~k 3. CHARACTERIZATION

Composition analysis.

of

Crystal

striations,

the

grown

crystals

morphology

growth

sector

cracks were observed.

Also,

and

was

determined

crystal

boundaries,

defects

by

microprobe

such

dislocations,

as

growth

inclusions

and

the optical c h a r a c t e r i s t i c s w e r e measured.

3.1. Chemical Analysis Chromium

concentration

Cr3+:Y(Ga,AI)3(B03)4 crystal

growth

(YGAB)

run,

and

must be larger than 1

it

in

the

Cr3+:YAI3(B03)4

and

crystals g r o w n by T S S G m e t h o d d e c r e a s e s w i t h indicated

that

the

distribution

coefficient

[29]. Its v a l u e was c a l c u l a t e d u s i n g the equation: K = Ccryst./Cmelt ,

were Ccryst"

and Cmelt are c h r o m i u m c o n c e n t r a t i o n s

the melt,

respectively.

As

result,

crystals,

and also 3.00 and 9.35

it was

in the crystal and in

estimated

for YGAB c r y s t a l s

to be

1.93

containing

for YAB

10 and 50

at.% Ga in the s t a r t i n g materials. In

the

case

of

spontaneous

neodymium

distribution

neodymium

concentration

coefficient

to 0.76 w h e n Y : N d = I : 3 definite

dependence

temperature AI203

nor

[41].

increases

initial

The

dependence

on

with

solution

authors

distribution

of

of

an

from

ratio

on

the

in

of the

for Y : N d = 3 : I

observed

the

between

mean

increase 0.40

this p a p e r

coefficient the

NYAB,

neither

crystal

Y203

growth

(Nd203)

and

in the s t a r t i n g solutions. However,

yttrium

and

there

is

neodymium

crystal g r o w t h p r o c e s s of

in the

of

its

crystallization

neodymium

were

another

between

the

fluxed

with

melt

of N Y A B by T S S G m e t h o d

determined

to

crystals g r o w n f r o m fluxed melts the s t a r t i n g mixture,

situation

be

1.2

and

and

Therefore,

distribution

solid

phase

of

in

the

[35]. The a v e r a g e amounts 8.2

c o n t a i n i n g 5 and

respectively.

the

at.%

for

i0 at.% Nd

using

the

NYAB

in NYAB

the above

in

equation

R ~ e ~ deve~pme~sinthegm~h ~ RM3(BO3)4cwstals the neodymium depends

on

distribution

the

crystal

with an increase

coefficient

growth

the growth rate of NYAB crystals

was estimated

conditions.

in crystallization

295

This

to be

0.3-0.8.

coefficient

temperature

It

increases

and with a decrease

in

(Fig.6 and 7).

4

.~

3

2

.....

I

¢

1010

I

,

1020

I

1030

T, o c

Fig.6. Dependence of neodymium amount in the NYAB crystals on the crystallization temperature

I

I

0

I

0.1

,,

[35].

I

0.2

V, oC/h

Fig.7. Dependence of neodymium concentration in the NAB on the cooling rate of a fluxed melt [35].

In

accordance

trigonal prisms

with

ref.

[27],

(I) and octahedrons

are related as follows:

the

distribution

coefficients

for

(2) in Bi-containing huntite borates

296

N.I. ~ o n ~ k

I) K y b + K E r > K y > K H o > K B i , 2) K A l < K C r > K G a > K F e The

(I) and

borates that, are

(2) p o s i t i o n s

with

general

are R-

formula

RM3(B03)4,

of the i n v e s t i g a t e d systems

the most

materials relation would

stable.

However,

in the v i s i b l e K A I > K G a , it

be

the

was

most

and M - p o l y h e d r a

in ref.

these

spectral

concluded

suitable

respectively. [27],

crystals

region. that

for

in a s t r u c t u r e

Taking

basic

was

inferred

(Yb, Er)Cr3(B03) 4 borates

cannot

the

It

of the

be u s e d

as

optical

into c o n s i d e r a t i o n

(Yb,Er)AI3(BO3) 4 composition

for

the

crystals optical

application. Also,

the authors

sizes w h e r e

the most

in r e f e r e n c e

[27] have

stable h y p o t h e t i c a l

found the range

cation

can be

located

It was c o n c l u d e d that the smaller y3+ cations will be m o r e the trigonal p r i s m p o s i t i o n s

than Er 3+ ones,

F~uilibrium¢ompotit~tm

(Fig.8).

suitable

to equilibrium.

R*

l

Ko AI3+~ Kp

Cr3÷

..!~------~

3+

\Ko

/

! IIl~-

,Y Jd÷ i

iii 0.50 Fig.8.

0.60

i 0.70

i,i 0.80

for

and the YbAI3(BO3) 4 borate

is the most stable and has the c o m p o s i t i o n closest

Me*

of cation

0.90

1.00

R6,A

Q u a n t i t a t i v e d e p e n d e n c e of the d i s t r i b u t i o n c o e f f i c i e n t s K o and Kp on the radius R 6 of the ions o c c u p y i n g o c t a h e d r a l (O) and trigonal p r i s m (P) p o s i t i o n s in h u n t i t e s t r u c t u r e [27].

Rece~deve~pme~sinthegm~h~ RM3(BO3)4cwstals According congruent Crystal

to

ref.

melting

[27],

a

compositions

further for

growth process parameters

direction

huntite

297

for

structure

research was

for each new crystal

of

the

established.

can be optimized

to increase the size and optical quality of materials because not all of the

melt

compositions

and

growth

parameters

were

perfected

in

this

study.

3.2.

Crystal

Morphology

There is a good deal of a recent data on the morphology of NYAB and NAB

crystals

[37,39,40].

Inclusions

and

problem of NYAB and NAB crystal growth.

cracks

are

Usually,

one

of

the

serious

the inclusions

are the

sources of the cracks. The chemical composition of the inclusions same as that of the flux used for the growth. crystals the

depends

cooling

raised

crystals and

rate.

below

inclusions

critically

and

and cracks

grown

seed

on seed orientation,

However,

1060°C

from

in

the

eliminated

[37,39,40]. Also,

planes.

Special

cause

the

rate

[37]. <201>

visible

the

of the grown

solution

seeding

was

reduced

to

eliminated

or

direction

<001>

and

2.4°C/day,

seed

for NYAB

for

and changing

inclusions

was

from the NYAB

on



flow and

temperature

By using

rate below 2.4°C/day,

periodically,

crystals

cooling

seeds

direction

the

though

could not be completely

reducing of the cooling

of

even

the

<100>

orientation

The quality

is the

NAB,

by

the rotation

cracks

could

be

induced stress during cutting and polishing

any microcracks

care is therefore

to propagate

along

the

cleavage

necessary during the preperation

of a

sample for laser engineering and nonlinear optics. NAB crystals,

grown from a BaB407

[39,40].

The

fast growing

composed

of

{iii},

monoclinic

NAB

{ii-i},

often

flux,

tend to grow in a rod shape

direction

is

{010}

{001}

misbehaves

and as

though

and the grown faces.

The

belonging

to

crystal

growth the

form

is of

hexagonal

298

N.I. Leonyuk

system. {2-10}

For

instance,

and

{Ii0}

the

{111}

and

prismatic

faces {Ii-i}

{010}

of

faces

the

occurs

with

the

comparable

to the

{i01}

faces of the hexagonal

the

{010},

2.4oc/day

{Iii},

{ii-I},

developed and also, <100>

direction

orientation

{001}

faces system.

seed orientation

{011},

{001},

and

these

along

the

faces



well

The

same

which

are

also

When the cooling

{10-2}

<201> faces

or were

When

the

well-

hexagonal

the

pillar

twinned crystals were formed with the twin law of a three-fold axis

,

[40]. Seeding in the

developed.

direction,

to the

system.

was

{11-2} and {012} faces appeared

makes

was

and the

comparable

hexagonal

situation

rate was below

and

are

seed shaped

rotation

[40]. The authors

of ref.

flux

NAB

crystal

grown

defects

[39] have

crystals

which were

investigated

using

included

an

optical

during

a surface

structure

microscope,

the growth

and

process,by

of

also using

X-ray topography.

3.3. Optical Characteristics

For the first time, were M=AI,

measured Sc

emission

[26.38]. in the

transition. also

are

and

their

near

IR region

case

associated in

RM3(BO3) 4

energy

high

spectra

vibronic

crystal-field in case

of

the

of

where

the

sharp

4T2--~4A2

Gd

and

showed

features

are

band.

However,

low

exclusively

structure

indicating Whereas,

Sc-borate

radiative

R-line

the broad

site.

R=Y,

spectra

show a strong broad band

with

and GAB,

wing

borate

spectra

associated

of the YAB

on the high

is observed

field sites.

Cr3+-doped

photoluminescence

situated

emission

the

The RT luminescence

In the

observed

temperature line

for

the optical absorption and luminescence

the the

only

suggesting

sharp Cr 3+

broad low

R-

ions band

crystal-

Recem deve~pmeNsinthegro~h ~ RMs(BO3)4cw~als

At the

the

same

optical

time,

the

authors

characteristics

of

of

YAB

ref.

and

299

[25,29]

YGAB

have

crystals

also

doped

measured with

Cr 3÷

(Fig.9-12).

b4

U4 .

.

.

.

I

422.0 •

.

.

.

.

.

~

592.0

,

•

i

.

.

.

.

,

.

.

.

.

I

.

.

.

.

N

682.0

•

~00

!

o

&O0

600

,

.

o

800

L,~..

900

(nm)

o

(a) o o o

. . . .

I

i,

•

423.0

,

~

,

~

'

"

,

i

.

.

.

.

.

.

.

.

.

I

'

'

'

'

o 0

o

601.5

o

o o 0 o o, o 0

go

o

682.0

o

o

6S475 0

g 0

300 ,

°

.

I,

.

•

,

,

,

,

,

.

•

&O0

,

I,

,

•

o

i

.

I

oOr~°° .

.

. •|

600

.i

I

r""- - -

900 o o

800

(nm)

(b) Fig.9.

The optical and

maximum

harmonic

A b s o r p t i o n spectra of the crystals: (a) Cr3+:YAB and (b) Cr3+:YGAB (25 at.% Ga in starting materials) [29] .

gain was m e a s u r e d

single-pass

generation

conversion

efficiency

gain

in the

UV

was

in the range from 744 nm to 852.5 nm, 1.92

region

at

820

(375 nm)

nm

was

(Fig.13).

Second-

demonstrated

of 1.6% using a 2.5-mm long Cr3+:YAB

crystal

with

a

[29].

300

N. I. Leonyuk

@10

I .............

C

3

I ....

! ....

T

T

'

"

-t..................'..................'...................

....

o- polarized

.........

I

"! "- i! --4' . . . . . . . . . . . . . . .

e-

t .........................................

. - .................. 4'. . . . . . . . . . . . . . .

I - ..................

i

"i e-

--

4 4 .......... {'-,ra~=""~ ....................~...................... +....................... .+................... !

e-" •

-~ ................................

~ .................. f ............... - - I

O

E

,i

0

650

Figol0.

....

i ....

700

i . . . . . . . .

!-

750 800 850 W a v e l e n g t h (nm)

-,

900

950

F l u o r e s c e n c e s p e c t r a of C r 3 + : Y A B c r y s t a l s (Cr was 0.5 at.% in the s t a r t i n g m a t e r i a l s ) . A SW H e - N e l a s e r was u s e d as a p u m p s o u r c e [29]

.-.100 •

'

'

'

'

'

'

'

il

'

'

'

'

'

'

'

"

'

'

'

'

'

'

'

'

'

t--

8o

....... ¢ .................... ;. . . . . . . . . . . .

& ................... • ................... 4 ................... 4 .......

m ....... i.................... "

i

E

~

i

i

~

i

i

i

i

900

950

40

t-ID

~

. & ................... • .................. ~ ................... 4 .......

i

20

O 3

u_

0

650

Fig.ll.

700

750 800 850 W a v e l e n g t h (nm)

F l u o r e s c e n c e s p e c t r u m of C r 3 + : Y G A B c r y s t a l s (Ga w a s 25 a t . % in the s t a r t i n g m a t e r i a l s ) [29].

Recent

~1

O0 ...., .

developments

,,

. . . .

in the growth

~'f~v ' , , ' ! I |i i

l "

i

of RM3(B03)

301

4 crystals

. . . . . . . . . . . . . . . .

"-

I-

~80

I - ............., ...............4 - - . I - . 4 - ...............~................, ................, ................., ............... ! i I !

I-

i lii

J

I-

it

!

k

!

I- .............. .~i ................. ,i . . . .r. . . . . . . . . .ix .........

~ "~

40

i

!

•

•

i

!

J

"

•F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

~ ..............

..................

600

650

700

750

800

850

Wavelength

Fig.12.

i

'r .................

1

0

i

"~ ............. T................T...............

"

............

t

i

$ ................. ~.................. . ...............

.............t .................

2o ,'r

~

!

i

900

950

1000

(nm)

F l u o r e s c e n c e s p e c t r u m of C r 3 + : Y G A B crystal (Ga was 50 at.% in the s t a r t i n g materials) [29].

2

I

I

I

I

I

I

I

I

I

I

'

'

I

'

'

'

'" .c:: 1 . 8

"'

'

'

.

. . . . . . . . . . . . . . . . . .

(9 c~ 1 . 6

...................t

~..........r : . .

......................:-.................

yil;iiiiiiiii[iiiiiiiiiill iiiiiiiiiiiiiiiiiiiiiiiill iiiiiiiiiiiiiiiii i i i iLi •

(13

0;', 1.4

,

i

i

i

i

e'- 1.2

o ~

1

i

740

i

i

760

i

|

i

780

|

i

i

800

Wavelength Fig.13.

|

j

i

i

820

i

I

840

i

i

I

860

(nm)

S i n g l e - p a s s gain s p e c t r u m of a 2 , 5 - m m long C r 3 + : Y A B crystal [29].

302

N.I,L~n~k The

Nd:YAB

authors

laser

of

ref.

[ 4 3 ] have

demonstrated

(end-pumped by an i n j e c t i o n - l o c k e d

the input p o w e r 531 nm output

the

TEM00

array)

output

of

a

as a f u n c t i o n of

(Fig. 14). At an 807 nm input of 500 mW the p o w e r of the

is close

to 50 mW.

For

comparison,

the

same N d : Y A B

has b e e n p u m p e d w i t h the TEM00 mode r a d i a t i o n of a T i - S a p p h i r e

laser

laser.

60

3O

10 0 0

200

400

600

pump power [mW] Fig.14°

531 nm output of a N d : Y A B laser p u m p e d by an i n j e c t i o n - l o c k e d a r r a y (open circles) or the TEM00 m o d e output of a T i - S a p p h i r e laser (dark circles) [43].

Flash lamp p u m p e d C r , N d : L S B lasers with 6.3% and 4.8% e f f i c i e n c y free r u n n i n g by

the

and Q - s w i t c h e d modes,

authors

of

ref. [44] . At

respectively,

the

same

time,

have b e e n for

high q u a l i t y and e f f i c i e n c y of new laser m a t e r i a l and

650

doped

~m

long m i c r o c h i p

LBS,

Fig.15.

respectively

For s i n g l e - m o d e

by a s i n g l e - s t r i p e

diode

was

a

obtained

provided

the

with

highest

lasers [45].

The

operation laser

pump slope

beam

were

fabricated

experimental

(Fig.16). width

efficiency

of of

The 20

from

LSB

lowest ~m.

63%,

of

the

two m u l t i m o d e

870

and are

25%

Nd-

shown

in

laser was p u m p e d

threshold

This which

test

10%

results

the 2 1 9 - ~ m - t h i c k

demonstrated

a first

LBS,

in

beam

of 38 mW

width

corresponds

q u a n t u m e f f i c i e n c y of 83%. At a p u m p p o w e r of up to 58 mW

also to

a

the m i c r o c h i p

Recem deveDpmemsinthegm~hofRM3(BOs)4c~stals

303

laser oscillated on a single mode at 1061.2 nm, At higher pump power an additional mode appeared at 1062.6 nm.

1400

~

z~ z~

1200

","Na~U~/:L~e""^'''~"

z~ A

• ,O Nd(25%):LSB

,~,

....

_ ~ ~

E lOOO 800

o

¢~. 4l=.= CL

600

0

2OO

o 0"

400

0

[ 0

250

500

750

1000 1250 1500 1750 2000 2250 2500

pump power [roW]

Fig.15.

Output power of 10% and 25% Nd-doped LSB multimode microchip laser pumped by either a diode array (dark symbols) or the TEMoo radiation of a Ti:Sapphire laser (open symbols) [45].

.-'

30

....••

¶•.•-•

"15 "5 o

e ./ . ~ . 0

T

30

-.

•• • ~

:

6O

:

90

pump power [mW]

Fig.16o

Output of the Nd:LSB microchip stripe diode laser. The solid of single-frequency operation, 58 mW the laser oscillates at

laser pumped by a singleline indicates the power range At an output power exceeding two longitudinal modes [45].

304

N.I. Lson~k

The laser performance vertical

was

to the pump beam.

of the Nd:LSB crystal. Nd :LSB

microchip

simultaneously for technical

insensitive

This

indicates

The experimental

lasers

to displacement

are

the good

of the chip

optical

homogeneity

results clearly demonstrate

very

appropriate

for

that

obtaining

important features of a light source which is of interest applications.

high efficiency,

These

features

high single-frequency

are

diode-pumped

output power,

operation,

and a TEMoo output

beam. Also,

concentration

investigated different

in Nd:LSB

conditions

quenching crystals

of pumping

and upconversion

for different [46].

were

quantitatively

concentrations

The upconversion

was

and under

found

to be

static.

4.

Thus,

CONCLUSION

the data available

AND

OUTLOOK

in the world scientific

end of 1995 show that in the early nineties paid to the single crystals Cr 3+. Large crystals Cr3+:YSB

have

trimolybdate various

been

grown

by whereas

growth

TSSG,

conditions

of the RSc-borate

from

Cr3+:GAB,

fluxed

and NAB

doped with Nd 3+ and

Cr3+:YGAB,

melts

single

using a BaB407

by the

the main attention has been

of RAI- and RSc-botates

such as Cr3+:YAB,

literature

based

crystals

flux by the

NYAB,

on

were

NGAB,

potassium grown under

same method.

crystals were also grown by the Czochralski

Some

technique.

Composition of the grown crystals was determined by microprobe analysis. Crystal X-ray

defects

included

topography.

Surface

within

growth

structure,

process

were

inclusions,

investigated

cracks,

using

dislocations,

growth sectors and growth striations were also observed. The lifetime

optical

absorption,

of the Cr3+:YAB

The spectroscopic

results,

and

luminescence

spectra

some other borate

and

crystals

optical gain measurement

fluorescence were measured.

in the range of 744-

Rece~ devek~me~sint~ g m ~ h ~ RM3(BO3)4c~s~Is 852.2

nm

and

second-harmonic

indicated the Cr3+:RM3(B03)4 self-frequency experimental lasers

doubling

the

laser

Nd:LSB

in

the

UV

region

materials

with

of

crystals

were

carried

out.

These

single-frequency microchip lasers.

the

RM3(B03) 4

clarification

crystallization

based on potassium trimolybdate high-temperature temperature order

fluxes

concerning

processes

which

the detailed occur

of

of

oxygen

structure.

magnitude

the

the

The fluxes

seem to be more effective and convenient

The viscosity

lower

than

crystallization

In addition,

alkaline

in

solvents for growth of borate single crystals with low-

huntite

at

borates.

results

for the design

fluxed melts in order to improve the quality of the crystals.

two

Also,

of the performance of diode-pumped microchip

A major problem which awaits nature

nm)

as new

tunability.

demonstrate that these crystals are appropriate materials of powerful

(375

crystals to have excellent potential

investigations

of

generation

3~

and

and

intensity

viscosity

temperatures

it would be useful

polytungstates

polymers

the

of these

other mass

of

also

flux

fluxes

of

B203-containing

the

huntite

to examine

agens

transfer

which

in

is one or

the

family

the potential destroy

boron-

crystallization

media. The

fluxes

tend to have RM-borate.

on the Li20-B203,

a significantly

They

substantially solvents

based

are

will

be

higher dissolving

practically

decreases

at

very

Na20-B203

effective

temperature monoclinic modifications

ability

non-volatile,

elevated for

and BaO-B203

and

temperatures. the

crystal

with their

appears

solutions

to

based

have on

high

RM-borates.

In this

for case,

crystal the

imagined as melts with an excess of some elements non-stoichiometric

melts).

to

viscosity these

growth

high-

of RM-borates and also,

potential

respect

Therefore,

the huntite borates which do not tend to phase transitions. flux

systems

for some of A Bi203-B203

growth

fluxed

of

of

melts

solid can be

(crystallization

from

306

N.i.tson~k

A choice of the appropriate and

crack

crystal

formation

growth.

On

which the

reduced by decreasing

is

other

flux is one of ways to reduce inclusion the

most

hand,

the crystal

serious

these

growth

problem

and

rate,

other

for

defects

increasing

rate of growing crystals and optimizing a seed orientation. there are no accurate huntite the

type

structure

temperature

important

data on the phase transitions

for

and

into monoclinic

concentration

improving

the

quality

of

of the

the

can

Also,

so far from

Investigation

of

transitions

is

phase

pure

be

the rotation

for RM-borates

modifications.

ranges

RM3(BO3) 4

crystals

and

solid

solutions based on these borates.

ACKNOWLEDGMENTS

The author is indebted to Ms.E.V.Koporulina typesetting

this text to camera-ready

for word processing and

form. Also,

the author would like

to thank Dr.H.G.Gallagher

(University of Strathclyde,

S.J.Chung

University,

(Seoul National

University,

Japan)

preparation NYAB

and

of

this

GYAB

International

for

the

update.

crystals

South Korea)

papers

sent

Non-published

(see

ref.[35])

Science Foundation,

Glasgow,

and Dr.M.Iwai

which

were

at present, was

UK),

the

supported,

(Osaka

useful data in

Dr.

for

on

the

part,

by

grant NCA000-NCA300.

REFERENCES

i. with

A.A.Ballman.

the Carbonate

1380-1383.

A

New

Mineral

Series Huntite.

of

Synthetic

Amer.

Borates

Mineral.,

Voi.47

Isostructural (1962),

pp.

Recemdeve~pmemsinthegro~h~RM3(BO3)4cw~als 2. N.I.Leonyuk, of Potassium

T.D.Semenova,

Trimolybdate,

universiteta,

and

Top-Seeded

neorganicheskiye 4. Crystal SSSR,

materialy,

N.I.Leonyuk,

seriya

Izvestiya

VoI.12

of

RE-Aluminium

neorganicheskiye

Akademii

Trimolybdate

Nauk

SSSR,

(1976), N 3, pp.554-555

A,V.Pashkova,

Morphology

(in Rusian).

of YAI3(B03) 4 in Potassium

Growth.

T.D.Semenova. Borates.

materialy,

seriya

(in Russian).

Crystal

Izvestiya

Vol.ll

Synthezis

Vestnik Moskovskogo

N 2 (1972), pp. 112-114

Solubility

Crystal

N.N.Sheftal.

New Flux for YAl-borate.

seriya geologia,

3. N.I.Leonyuk.

T.I.Timchenko,

307

Growth

and

Akademii

(1975),

nauk

N i, pp.181-183

(in Russian). 5.

N.I.Leonuyk,

N.I.Belov.

High-Temperature

of Anhydrous Proc.pp. 6.

Borate

310-316

Borate

L.I.Al'shinskaya,

Crystallization,

Single Crystals.

A.V.Pashkova,

Composition

XI Meeting

and Morphology

IMA, Novosibirsk

(1978),

(in Russian).

L.I.Al'shinskaya,

Crystallization, Gallium

T.I.Timchenko,

N.I.Leonyuk,

Composition, Crystals.

T.I.Timchenko.

Structure

Kristall

und

and

Certain

Technik,

High-Temperature Properties

Vol.14

of

(1979),

REN

8,

pp.897-903 7.

L.I.Mal'tseva,

Earth-Ferrous

Borates.

N.I.Leonyuk, Kristall

T.I.Timchenko.

und Technik,

Vol.

Crystals 15

(1980),

of N

Rare

I,

pp.

35-42. 8. N.I.Leonyuk, YAI-

and

YFe-Borates

Internetional Moscow.

A.V.Azizov, from

Conference

L.I.Mal'tseva.

High-Temperature on

Crystal

Growth,

Crystal

Solutions. Vol.3

Growth

Rates

Abstracts

(1980),

of

of VI

pp.262-263,

308

N.I.L~n~k 9.

A.V.Azizov,

Temperature

on

Temperature i0.

of

Lifetime

Pumping

16.

Conf.

Properties

as

on

High-

N 2, pp.296-298. A.V.Pashkova,

New

Crystal

Materials Growth

L.B.Meissner, of

(YAB)

K.Dwight. a

Isomorphic

Structure.

Crystal

Promising

H.Y.-P.Hong.

Optics

Phys.,

Commun.,

for

(1979),

T.I.Timchenko,

Family

Kristall

Structure

Laser

of Crystals und

and

Material.

Nd 3+

Vol.18

by

Vol.ll

Technik,

Fluorescence

Mater. Res.Bull.,

Cr 3+ (1978

Generation

Active-Nonlinear

teoreticheskoi

Vol.15

fiziki,

(1975)

NdP4014

in Acentric

NdAI3(B03) 4

N 3, pp.345-350. and NdAI3(B03) 4 Lasers at 1.3

(1979), pp.77-80. G.Huber, in

H.G.Danielmeyer.

Nd(AI,Cr)3(B03) 4

Lasers.

Efficient

Cross

J.Phys.,C:

Solid

pp.2399-2403.

L.M.Dorozhkin,

A.V.Shestakov.

CW Laser Action

H.G.Danielmeyer.

H.-D.Hattendorf

State Phys.,

Borates

from

pp.1661-1665.

S.R.Chin,

of

RE

Europ.

Borate

NdAI3(BO3)4,

14. G.Huber,

15.

(1981),

L.I.Al'shinskaya,

N.I.Leonyuk,

Optical

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