Simple structure model of high Tc oxides

Phpi= C 11t5-189 (1991) 70~-704 North-Holland

SIHPI.E

HOI)EI,

STRIICTIIRE

Chikao Katabata

OF

and T a k a m t t s u

Okayama U n i v e r s i t y

Computer

II1(;11

I'~

i)~Ii)1;7

Nakanlshi

Center,

Okayama 7 0 0 ,

Japan

Structure models of perovskite type copper-oxide h i g h Tc s u e , , : : : , d u e l e r s ",~s(.d ~>n lmag,, t ' r o c e s s ~ n g finalysis of (.lectron microscope photographs a r e g i v e n by r e . p l a c i n g t h e ,~tom al th(, b ~ , d : - c , . n t , . r c d site of the perovskite structure )ith smaller i o n i c r a d i u s at()ms. Th~:se h i g h i c o x i d , , s ~ r u c t a r ~ models consist of ionic-crystal bondings. )le c a l c u l a t e d maximum c r i ' i c a l ten, p c ' r a t u r ~ ' s " c ' s f,)r I,'t. ilA, ilia a n d ilIA l a n t h a n o i d s groups in t h e p e r i o d i c table of ch('mical elem(,nls k'e d i s c u s s the critical ionic-radius r c of superconducting phase transition.

1.

I~TROD~CTION We h a v e s t u d i e d

versus

spacing

sheets

along

processed a

linearlike

d between the

Tc d e p e n d e n c e

Cu-O(or

c-axis

other

photographs

Tc s u p e r c o n d u c t o r s

of

Tc

~

formula

conductors empirical

out

x

can

f o r m u l a e~

h type

and B t y p e

perovskite

structure

in

be

in a u n i t high

fit

cell

the

the A type ionic

models

Tabl,.

~,, , d - , t a i n , , d

of

image

region

of

the

bonding

between

the

at

concept

that

atom

the

(r/~)

of

on

structure

(d~)

between

along

the

is

ionic plus

(or

~as obtained

case'

on,- a f t , - r

f>rmula

r, s u ' , i , ;

~r,'

(l)

~,h~,~n

:n

maximum c r i t i c a l !! '.. l[!. ~. ~.-.'! !lt.~. p , ' r i , , d : c t a b l e ,.f

2sine

on t h e

of

radius

>

r

to

be v e r y

>

0.92~

contrary, 139.8K).

(17.7K

in it

the

case

p(,rf~skito

struc:ur,,

sheets

:,f

simple

the of

0 9 2 1 - 4 5 3 4 / 9 1 / $ 0 3 . 5 0 © 1991 - E l s c v i c r

(:xistence.

proportion-

ionic

image

S c i e n c e Publishers B.V.

because

bonding

Furthermore. that

it

Tc <

caa

¢;

139.8~).

our high

All rights rescrved.

it

on t h e it

is

it

of existence,

b,:

r <

0.92~

is

(Tc

difficc{t t'

f:zr

t-

3, of

t~'

i= t ~ <

5:!~.

17 7k}.

seems t e b , " d i f f i c u l t

is

difficult

Cu-O p l a n e very

Tc s t r u c t u r , ~

Ir

t,, ke~p '~,"

of

interesliag mo~el

seees

gn !h,"

less p r o b a b i l i t ~

nc.dc, l s

Tc s u p e r c o n d u c t o r

(2)

(O = 4 0 . 0 1 ° ). the

models

i~:nic-crystai L,.=:i;rg (F:~.2). In t h e c a s e o f r > I . S 2 A (Tc

high

~1.286

<

seems to be

spacing

* r )

th." ~n

ionic-crystal

Tc s t r u c t u r e

much p r o b a b i l i t y

the

following

~,:th

~s s h o ) n

classified into either chemical stable state or chemical metastable state. In t h e c a s e f i 522,

elements)

to

nodel

of

state

high

because

the

basis

overlap

these

oxistezce,

in c a l c u l a t i n g :

and

is based

(1.40/~)

ionic

Une s t r u c t u r e

From t h e

of

atom of

other

Namely.

a

radius

' ~ ! ~"~ "aT, ~., ,~ ; . ; ' r , , ~ . nt

perovskite

site's

obtained. a × ( 1.40

constant

radius the

proportional

Cu-O

~e s u c c e e d e d ality

the

c-axis.

equation is d ~

the many

DISCESSI05

bondings,

i o n on t h e

site

ionic. The model

side

3.

d is

the oxygen

is

body-centered

type

t 0 ° in

,':,l,:rica'.

th,.

go(,d

F i g . 2.

Tc

temperature,

body-centered

structure

oxygen

4s

is

O cL, in

of

smaller that

spacing

and

by

site

)ith

versus

that

on t h e

O ~

i,~nic

,,ur

t ~ , m p ( ~ r a t u r e s Tc's f : ; r I '.. l a n t h a n < : i d s ~rc, u p s in t h ,

experlments.

of

superconductors

structure

side

perovskite

model

We h y p o t h e s i z e d

,ide

ion

2.

d,tta

),¢ c a l c u l a t , , d

various

spacings.

the body-centered

dependence the

%ext.

for

0 9~.'.

vala, ~ 0

numerical

w,~. a p p l i ( . d

(h," , . ' t ~ i ; ~ . . ~

copper-oxide

atoms.

in

"d"

122k r

3)

~,e f o u n d

t"l t h c s ( '

Tc s u p e r c o n d u c t o r s

structure

perovskite

linearlike preserved

ic

atom at

radius

Thus.

II-

radius

ch,-.mical c ; ( ' m r ' n : s ?~ Ksp,'ciall.~. in t h e c ~ s , ' : I III.% i a ' l t n r ~ n t ) : d a g r ~ . ~ ; , s ( c . , , r d : r ' a : i . . . n ncmb, r : @).

high

type

replacing

I 4)

= 2 sinO.

J,)nJc

experiment

by o u r

Tc A%D STRCCICRK MODEl.

perovskite

our the

Table

another,

F i g . l.

We p r o p o s e

that

of

a

sit('.

,ith

spacings super-

so far

are

It

(1)

many c o p p e r - o x i d e

discovered

copper-oxide

2.

d + 611.76

that

processed sho~n

equation:

d -- 3 073~ ~, f()r

~)lth Ca 2°

body-cent(.r,'d

consistent

~'~)

as

spacing

(123,1)

~'e f o u n d

microscope's

is ~ritten

" 158.20

We p o i n t e d

of

high

at

structures

on e l e c t r o n

empirical

elements)

in p e r o v s k i t e

by i m a g e p r o c e s s i n g This

,~)sl,.m

~odc[(r

this

t:. c - - . - :

in ~ [ c a

t '

C Kawabam, T. Nakanidu"/ Structure model qf high Tc oxidea

704

Cu

0

0 m

a-b

Nd/Ce

Ca

u

A type

B type FIGURE I A type ~nd B type ~ d e l s of perovskite structure in a unit cell of image processed copper-oxide high Tc superco~uctors.

,•

C u

¢.? tt

0

~'

C ~

C u

0

atom

centered

0

(a)

i I

Oe

ll',~t.a,Cu)O~,

125

39. 8,6

(" ~9. 1 9

tlBa,r-~C,,O,

110

39.

39.

103 99

'i'l~l~r'C~O) TI ~ , ~ a C , ~ , YBI,Cu,O~. ,,~ B h l S r I . wC4io. ,¢~z,Oo.r

68

38.

I

95

39 • 70 39. 90 41 • 06

IB~zCu,O.

80

40. 8 3

~l~Cu)O,.,~

50

40.

e ©e

(")

29

::::'31.

67

;:::'29. 30.

38. 71 36. 28

54

71 39 45 33 41

30. 60 31. 85 31. 31.

40 43

36. 36.

t'q~eInK d

~::;'29. ;:::'31.

31,

05 52 16

k.

(a)The

definition of angles 0 ou, 0 o, 0 ~ . , of A type perovskite structure. (b) O ¢u. O o. O c , o f each s u p e r c o n d u c t o r . tkelltll

(a-2slnS-l.2858~ lanlc r~.AI

-~-'iY~.o~';B

K"

6)

II A

i~.i.-~, iM K r. INI S r * ' (fi) O a t' (G) s c '" ~

-iiih croup

Y~"

I

L ~ ¢" (fl) C e * ' 161 P r ~" (51 Nd" (8) Pro*" Sin'* [~. '* Gd** T b " I) y s.

E r ~"

(8) (~) (G) (G) (fi) (8) (O)

'I'm ~" re) Y b ~" (8) L u ~* (fi) I.n ~* 18) L ~ ~" (~) C ~ * " (g) P r ' " 181 N d =" lg)

-----

G d ~' "l'b ~' ()y~' I I o ~' Er" T m ~" Y b ~' Lu"

(8) 19) (9)

hydrogen

. . . . . . . . 5lm¢lnl

IIIUI

;

d (A)

out

¢ (KI

i. ?----~'~"

35.

O. GR J. 9 7 I. 33

Z. 6 7 4 ~. 0 4 7

BS. 7 ;~9. 7 ~6. 5 17. 7

-~7-~ ). ~3 :1. ;I . (61~

Z- 2 Z , | Z. 6 4 " )

!=_5 z__

I{b'

......

'

tt'ld l d l ulUl S

coord Inll| I Des

:1. ¢J9 ] . . 1] 6 9_...._ ;. 6_ I. 3. -- 81 3- 9 2

1. 1 4

}.

510

3:.v~s_ 3. 0 7 " t ' 3. 2 9 Z

L_S,I_v ~2. 8 4 2 2.

983

3~ 2 6 6 . 1 --

I~ O ~

I 3. 1 7 6

I. I. I. I. O, o. t,. O. O. O. O. O. O. I. I. I. I. I. I. |.

0 64 02

J 3. 3 . 1 63 37 3. i t 2

O0 9R a7

3. 086 3. 060

Q3 92 91 89 87 86 85

18 28 22 21 19 16 14

3. 2. 2. 2. 2. 2. 2.

047 996 983

970 944 919 906 Z. 893 3. 3 1 7 3. ,146 3. 3 0 ~ 3. 356 ~. 3 3 0 3. 2 9 2 3. 2 6 6

I. 1 I I . 04 1. 03

3. 3.

227 I 37 L2,1

O. 9 3

2. 996

7 O

~1.

t)

39,

8

~ 5 "

l

site, turned

stabilized.

37. R

REFERENCES

R 9

40.0

Sn.o

~i.

face-centered Tc~335K.

CONCLUSIONS Our r e s u l t s suggobt that the appearance of h i g h e r Tc m a t e r i a l s than current Tc~I30K levelsuperconductors Is p r o b a b l y n e a r a t hand and t h a t h y d r o g e n ion w i l l be t h e most s u i t a b l e atom for creating a h i g h Tc s u p e r c o n d u c t o r a t room temperature level, if such a structure c o u l d be

O9 ~I II.4 15.5 19.4 23.6 27.7 29.7

5,1. 87.0 66.6 78. 80. 84.9 91.

at

4.

~,~--,~-

~2.

ion exists

t o be t h e h i g h e s t

I

~2. 2~.

39. 41.

I

F I GURE 2 Iligh Tc s t r u c t u r e model v i t h Mg2"(6) ion a t the body-centered site of perovski te type structure model, r=O.66A, Tc=192.7K

t ~)

TABLE

.1

.',, (o) "~ elevation view

z

(h)

8~40.01"

(b)

side vlaa

Cu

Cu

0

(a)

plan

0

I

I

I.

I I

C . ~ a ~ a b a t a and T. N a k a n i s h i , Read at 7 t h - W o r l d C e r a m i c s C o n g r e s s (Symposium 4, }[TC s u p e r conductor) Trieste, I t a l y ( 2 - 5 J u l y , 1990), ( t o be p u b l i s h e d in P r o c e e d i n g s by E l s e r v i e r Science Publishers 1991)

8 0 0

2. C. K a , a b a t a and T. N a k a n i s h i .

11~.

2

117.

5

137.

8__J

59 (1990)

J.Phys.

Soe. Jpn.

3835.

(8)

iS) re)

(8) (B)

TABLE 2 Table of the maximum c r i t i c a l temperature Tc calculated by the perovskite type structure models for various ionic radius of chemical elements.

3.

C. K a w a b a t a and T. N a k a n i s h i , 60 ( 1 9 9 1 ) 1138

J . P h y s . Soc. Jpn.

4.

K. Yvon and M. F r a n c o i s . Z. P h y s . B - C o n d e n s e d M a t t e r 76 ( t 9 8 9 ) 4 1 3 - 4 4 4 .