Synthesis of single crystal SnS2 by chemical vapor transport method at low temperature using reverse temperature gradient

Journal of Crystal Growth 106 (1990) 593—604 North-Holland

593

SYNTHESIS OF SINGLE CRYSTAL Sn52 BY CHEMICAL VAPOR TRANSPORT METHOD AT LOW TEMPERATURE USING REVERSE TEMPERATURE GRADIENT Takashi SHIBATA, Takashi MIURA. Tomiya KISHI and Takashi NAGAI Department of Applied Chemistry, Faculty of Science and Technology, Keio Unicersity, Hicoshi 3-14-I, Kouhoku-ku, Yokohama 223, Japan

Received 5 May 1989; manuscript received in final form 17 March 1990

Using the chemical vapor transport technique at lower temperature than that ever reported, single crystals of SnS2 were successfully grown. The reverse temperature gradient (the transport zone at T1 = 419—438°C and growing zone at T, = 449—455°C) was another characteristic feature in this method. The reasons why SnS7 single crystals can he grown at low temperatures were investigated from the view point of impurities, particle diameter, chemical binding energy and crystalline condition of the starting materials. It was found that lattice defects generated by grinding polycrystalline SnS, and decomposition products of SnCI4 or SnCI45H20 as transport agents were necessary for the growth of single crystalline SnS,.

1. Introduction SnS2 found as the mineral berndtite in nature [1,2] is known as a two-dimensional layered cornpound with Cd12-type crystal structure and has become the object of many investigations [3] in the field of electronic materials. The authors have studied the photoelectrochemical behavior of this [4—6]and related compounds. For these studies, it was necessary at first to investigate the synthesis of unique (single phase) polytype [7—12]single crystal. The chemical vapor transport method, whose theory and techniques had been established (Schafer [13], Kaldis [14] and others [15]), has been employed for the crystal growth of SnS2 by many workers, as shown in table 1. They obtained SnS2 single crystal using ‘2 as a transport agent under forward transport, while the existence of both forward and reverse transport has been investigated by Wiedemeier and Csillag, using Sn14 as a transport agent [16]. We report here the results of synthesis and crystal growth of SnS2. Using SnS2 powder as a 0022-0248/90/$03.50 © 1990

—

starting material without addition of 12 as a transport agent, and maintaining both transport zone (T1 429 ±9°C) and growing zone (1’, 452 ± 3°C) at lower temperatures than those in previous work [7—12,17--28,30—34,38—42J (T1 950— 680°C, T2 700—550°C),SnS2 single crystals (10 x 35 mm, <600 ~sm thickness), which had a larger volume than many others reported hitherto, could be grown. The reverse temperature gradient in the direction of material transport in this case is interesting, as it indicates an exothermic transport reaction. Sublimation can, therefore, be excluded. Various growth parameters were investigated, such as impurities, particle diameter, crystalline condition, and chemical bonding state, using mass spectra, JR. EPMA (electron probe X-ray microanalyser), particle diameter distribution, TG/ DTA, X-ray diffraction analysis and XPS. The results showed that by grinding polycrystalline SnS2, the surface area of the prism face increases, and crystal lattice defects are introduced, which cause SnS2 to be in an unstable state. Under these conditions, the decomposition products of SnCI4 or SnCI4 5H20 act as transport =

Elsevier Science Publishers B.V. (North-Holland)

=

=

=

594

T. Shihata et al.

O

0’ —

0 N

— N

.0 0’ N 0 N N 00 N 00 N

N

/ Synthesi.s of single

0’ N

00 9 ,—. N 00 0’

00000000000000000000000000

00 N

—

(‘rlstal SnS, by CVTa LTusing RTG

00 nO

— N

0000000000

.0

0 —

N N 00 00 _, 0’ 00 N00N

— ,_. 0000

,_. 00

‘0

0’

00

0’

0’

— ., 0 0 —

—

—

—

0 N —

0 ‘, —

C

~

0.

oi.

~

0.00,000.00 — C C rI — —

0 —

— NO

0’’000’0’0’0’0’000’

a

O —

.0

~o~o 000 ~‘

0

-~ CC—, 0000

0_ >00 ~o

I

0 ,

~

..~

., 00 ~

~‘~55~

0 ~. 0, .~

~

<

—~00~O

~0.~Et’t00_

~

000 0000

j~j 0

~ij

_o.t.E~~ ~ E_0’0

ttoE~oE~ 00000

0000

C.0’000

~

00 0’-

S a I

— N~ = N I

O

— I

I

I I

N

00 — I

I

I

~

N 0’N,-’N,

~ N

—

‘0 I

I

0 -~

-~

0 ‘00?

-~ I—

0

I

~

I

X

10...

!~

~.

2

E90~9~~E

00999

E

.0000N-,000r’101,_,

000100

~

0,0

N

.0

700

“a

I

12

N 0 -‘‘0

I

I

I

I

Not—

0

00

0?

I

3 NN

00

3

00

I ‘000,0

.-‘N

‘0 0 03

~‘—~

00

0? “0

-~

ONON0000N100 00’’N 00

.0

---

00 N N— —

00 — I

I

I I

0?S I

‘0

‘~

0? I

~

0?

0?

0?

0? 0,

00

II C .0

~

0

I ~‘

‘0

‘0 N

‘0 ‘0

00 ‘0 ‘0 ‘0 ‘0 ‘0

.0 ‘0

I

C

.0 .0

.0

00

I It

-

~‘‘~ .0 ~

‘0CCO~N 00

‘0

.0 ‘0 —

.0

00

i’

t

~ 00

~‘

0’

90 00 00 N

‘0

00 N

00 ‘0 ‘0 ‘0 N

I

IN .0

00 ‘0

00

00

00

.0

00

‘0

0

I

~0100 N 0

00

00

00

N

00

00

00

00

‘0

N

0

00

0

00

~ 00

C 01

C 00

—

0?

—

0

0

0

0

00

00

00

00

—

E ~ 0.

0)

-

10

~

~“E~ 00

lot

~ -

XX

X

X

00001

NI’0

X

X

.0I’

OOX

X

N

00001100

X00

00 I

1110090

—

___I

—

———I

—

NC

~Ch~

~.)

—

~ I 0

I

X

0

0

0

N

00

—

0

I I

—00

Th 00

—‘5fl

00

~, 10

CO

~ ‘0

NON

,~l 0?~

a.

Oat

“I

t

It

I

I

El

0

~

‘-.N

N

N

NN

N

30

‘ 00

00

I

ON

— ~

01 00

00

00

0

00 00

00. I N

00 I NO

N0 I N

0Th 1 N

N

“E N 00

I

I

E

I

to

00

00

‘S

00 00

N

—

0

00 00

~ ~

H

00 00 I

00

N

I

I

El

I N

N 00

O oj ~0’-

N

00

00

00 00

00

00

00 00

I

I

,to

I

‘0

00

0

0

I

N

0

0

0

I

I

“E

N

1

‘~ =

~

0

00, V

— —

.~

0....

.0

30

I

I

I

I

N

N

I

I

I I

I

I

— 000

_O -~

o

2

C

~

0

~‘

—

fl

Is

~E ~O

00 00001

00 CCC 000000

CCC ‘00000)00

HHHHHHHHHHHHH

O~ 00

I

i’ ~

0.000.

1

00

. CC 0/0000

C 1000

>>;0>>>>>>>>>>

~HH ç>>

~

H0~’0~

C 00

H >

> LO

0000 C 00001

CCC 000000

00

00

0 0/0

oo = 0/0

HHHH

HH

H

H

H

H

>>>>

>>>

>

>

>

>

(00

‘~

=

I

C

Co

T Shibata et al.

/

595

Synthesis of single cr stal SnS, hi’ CVT at LT using RTG

agents of Sn, and the synthesis of single crystal SnS2 by chemical vapor transport at low temperature (lower than 450°C) can be achieved.

2. Experimental

2.2. Analyses The characteristics of the starting materials (1, 2 and 3) were examined by the method described below. The particle size distribution of the starting matertals was measured by the centrifugal sedimentation method (Horiba, CAPA-500). The morphology of the samples was observed with SEM (JEOL, JFSM-30) and XPS (JEOL, JPS-9OSX) spectra were taken using X-ray radiation of Mg Ket (E 1253.6 eV). A binding energy correction was done assuming a binding energy of adsorbed C on the surface of 285.00 eV. The crystal structure was determined by X-ray powder diffraction (Rigaku Denki, RADIIA) at room temperature using reflection data collected in the range of 3°~ 20 ~ 140°. Cu-Kct radiation and a graphite monochromator were used. TG/DTA (Rigaku TG/DTA 8078G2/Thermal Analysis Station TASIOO) of each powder and of single crystal 2H-SnS2 cut up into ca. I x 1 mm squares was performed under air atmosphere between room temperature and 1400°C with rising rate of 10°C/mm in a Pt pan. Al 203 powder was used as DTA standard, A mass spectroscopic analysis (JEOL, JMSDX302, JMA-DA5000) was performed, using a direct injection method to insert each sample into a quartz capillary. The temperature was raised from room temperature to 385°C at a rate of 10°C/mm, kept at 385°C for 10 mi and then cooled gradually. The measured range was 12— 1500 in M/z, with an accuracy of two decimal places, using PFK (perfluorokerosene) as calibration standard. The TIC (total ion chromatogram) as a function of temperature was also obtained with this method. A vacuum of 10~ Torr was kept throughout the experiment. -

2.1. Starting materials

SnS2 power (1) (Soekawa Rikagaku, Lot 42680, 100 mesh powder ultra-pure grade reagent) was used as a starting material, The list of impurities in this material appended to the reagent analyzed by ICP is as follows: Ag 0,0005%, As 0.1%, Bi 0.001%, Cu 0.001%, Fe 0.0005%, In 0.001%, Ni 0.001%. Pb 0.05%, and Sb 0.1%. Various SnS2 powders, synthesized by several methods described below, were also used as starting materials to clarify the factors affecting the crystal growth mechanism. A stoichiometric mixture of Sn powder (Koujundo Shiyaku, 100 mesh powder 4N 3.246 g) and S powder (Soekawa, SN 1.754 g) was put in a quartz tube of 20 mm inner diameter (24 mm outer diameter) and the tube was evacuated by oil diffusion pump up to 106 Torr and sealed off at a length of 150 mm. The tube was set in an electric furnace (Isuzu Seisakusho, Model RTC 5130A) of final temperature of 650°C [34]. with the temperature profile shown in fig. la, for 24 h (2’). In the same way, a mixture of 1.500 g of the promoter NH4CI (Taisei Kagaku. reagent grade) [35—37],3.246 g of Sn and 1.754 g of S in a quartz ampoule was heated in the furnace at a final temperature of 400°Cwith the temperature profile for 30 h, as shown in fig. lb. The product was washed with pure water (deionized and distilled) to remove the promoter and separated by a centrifugal separator for over four times, collected on a membrane filter (Advantec Toyo, Cellulose Nitrate 0.45 ~tm) and dried under reduced pressure at room temperature (3’). Each 4 g of 2’ and 3’ were placed in an agate pot with internal cubic volume of 287 ml and 14 agate balls of 15 mm diameter and 39 agate balls of 7 mm diameter, and was ground by planetary mill (Fritsch) for I h at room temperature (2 and 3). —

-

-

=

2.3. Synthesis of single cri’sial

The quartz ampoule (outer diameter 15 mm. length 150 mm) which contained 2 g of SnS2 powder was sealed off under a vacuum of l0~’ Torr, and was placed in the furnace (Siliconit Kounetu Kougyou, SPSH-30. Control Unit: Chino Seisakusyo, NP-163A, Sylister Regulator: 0L78

T Shihata et al.

596

/ Synthesis

of single crystal SnS~by CVTot LTusing RTG

BOO

a

-

ooo—

,// /lOhr

-

.~

400

(650°C) 24hr \ (400°C)

4200C

—

2o:~

Time

h

hour

C

UI

~

~ 5o0-~~ ~ 4OO-~ 0

/

~‘

5

10

15

Distance / cm Fig. 1. Temperature—time profile for synthesis of polycrystalline SnS 00 as starting materials in an evacuated quartz tube (a. h). and temperature—distance profile for synthesis of single crystal SnS2 (c). (a) Stoichiometric mixture of powder Sn and S (2’). (h) Same as (a) with NI-I4Cl (3’). (c) I. powder SnS00 (1) in a transport zone; II, synthesized polycrystalline: III, synthesized single crystal SnS~in a growing zone.

XC1I5) with the temperature profile shown in fig. Ic for ca. 3—8 weeks. Under these conditions, the most remarkable growth of single crystal was obtamed in a preliminary experiment using the starting material 1.

2.4. Analysis of by-products

Some transparent 3 crystals and yellow in addition to theparticles single smaller were thandeposited 1 mm at both sides of the quarti. crystal

T. Shibata et at.

/

Synthesis ofsingle crystal SnS, hs’ CVTat LTusing RTG

ampoule after the synthetic experiment using 1. The structures of these by-products were determined by EPMA (Shimazu, EMX-SM), IR (Hitachi, Type 225), X-ray powder diffraction and TG/DTA.

3. Results and discussion 3.1. Synthesis of single crystal

The crystals synthesized from 1 were large, thin plates (fig. 2a), crimson at high temperature and yellow to orange colored at room temperature. Fig. 2b shows the SEM view of an edge. Some twin crystals are found and all of the crystals have extremely flat surfaces. The crystal size was limited by the inner diameter of the quartz ampoules. Some of them were grown to the shape of circular or elliptic along the inner wall of the ampoule, and some others were radially grown to several petals around a center, each of which consisted of several single crystals. It was confirmed by X-ray and electron diffraction methods that each of the plate shape crystals was a hexagonal single crystal grown along the c-plane. Further details of the structure and characterization of the SnS 2 single crystals will be described elsewhere. The single crystals obtained can be roughly classified into thick and thin ones with the naked

597

eye. The thicker ones had larger plate areas and grew up to 3.5 cm2, and <600 ~im thickness. Some of them had a hexagonal growth pattern. These sizes are much larger than those reported in the literature from chemical vapor transport (1—2 cm X 0.1 mm at most) as shown in table 1. Only by the temperature oscillation method was it reported that the single crystal grew up to 30 X 25>< 0.1 mm at 690—645°C [38]. From the starting materials 2 and 3, single crystals grew only a few mm2 at best. The differences in the results of single crystal growth were analyzed in some detail. 3.2. Necessar conditions for single crystal growth

No influence of the addition of As and/or Sb on crystal growth was found when the materials 2 and 3 were used (dopants were sulfides). Therefore, metallic impurities seem to have no influence on the crystal growth. SEM investigations showed that the primary particle diameter of I was smaller than 3 and particularly smaller than 2 (figs. 2c—2e). One could. therefore, assume that 1 had a larger surface area than 2 and 3, and might have a larger reaction rate. The secondary particle diameter distribution of each powder was similar. This means that it could be ruled out from the controlling factors. Some XPS data of the starting materials are shown in table 2. Though chemical shifts occurred

a

Fig. 2. A photomicroigraph (a) ano SEM ies~(h ol single crsoi,il SnS~..ind SEM iesss of siariing iiiaierialo (o—e). (a) Lamella formed single crystal (350 ,sm thick). Marker represcnio I cm. (h) View on in edge. (c) Sample I (Soekassa I oi 42n50). (d) Sample 2 (ground specimen of polycrystalline SnS, synthesized ii 1o50”ty Ic) Sample 3 Iyrund specimen of pkcrssialline SnS~synthesized at 400 ‘U ssiih NH..Ul)

598

T Shibata et at

/

Synthesis of single c r~ stat SnS h~C VT at LT using RT(,

between powder and single crystal bulk (for Sn 4d /.3/’ Sn 3d5/ and so on) owing to surface adsorption species of C and 0, remarkable differences in chemical bonding state of each partides were not observed. Fig. 3 shows the X-ra?y

diffraction patterns, in which the diffraction lines are indexed as 2H-type crystal. As all the ground materials, 1, 2 and 3 (the diffraction patterns for 3 are similar to these for 2) had a broad diffraction pattern near 20 30°. Compared with a SnS =

~

_

N

~

0,

_

_ _

0

~ I _

0

j t!:~~ Fi ‘

—

(.~)iitiiii~>il

T. Shibata et at.

/

599

Synthesis of single crystal SnS, by CVT at LT using R TG

Table 2 XPS data (binding energy) of starting materials; numbers in parentheses represent the value of the FWHM

1

M00D~

002)

Binding energy (eV) __

S S

2s,~ 2p~> 2p~ 2~J.2

S

~

Sn ~ 3Pi 2 Sn 3d 5~ 3d~2 Sn 4d 001

II

1 226.20 (2.41) 161.80 (2.27) 161.75 (1.30) 162.95 (1.40) 17.60 (3.39)

2 226.20 (2.28) 16’~.80(2.1!) 161.70 (1.20) 162.90 (1.20) 17.30 (2.90)

3 226.15 161.75 161.65 162.80 17.50

102))003, (2.24) (2.11) (1.20) (1.20) (3.19)

716.70 (3.75)

716.65 (3.56)

716.70 (3.60)

758.75 (3.38)

758.55 (3.30)

758.85 (3.52)

486.95 (1.75) 495.55 (1.72)

486.85 (1.44) 495.35 (1.41)

486.85 (1.51) 495.25 (1.44)

26.10(2.31)

25.95 (2.19)

25.75 (2.23)

Before 4d5002 separation 25.80 (1.30) of the coupling 25.70 (1.20) peaks. 4d1 26.95 26.80

2 MOO)

~DI3)

25.60 (1.20) 26.75

polycrystal (not ground), the (100), (101) and (102) planes of the ground materials seem to he in disorder. But distinct differences in the patterns of the materials I and 2 could not he observed. TG/DTA of the material I and of a single crystal 2H-SnS2 are shown in figs. 4a and 4b. For the single crystal. the sudden weight decrease corresponding to the exothermic decomposition of SnS2 to form Sn02 and SO2 appeared at 500°C. The final product was confirmed by X-ray diffrac-

0)

Ill

3

flfl~)

3’

003) (002)

tion method to be Sn07. The corresponding peak of the material I. on the other hand, began below 350°C, and the gradual weight loss began already from 50°C with endothermic reaction, which was

to he caused by the existence of an impurity. which is probably SnCl2 .2H20, if we judge from TG/DTA data of the samples. Other possibilities not observed in 2 and 3. This phenomenon seems of impurities, like adsorbed water, cannot he excluded. The weight loss in the lower temperature

observed the crystalin growth the material processI presumably at lower temperature relates to lound in this work. and therefore, we assume that S. Sn or SnS0 is transported into the gas phase liv the impurity. The Tl(’ as a function of temperature is shos~ii in l’ig. Sa. It is obvious that I had more ionized fragments than 2. Three peaks of the TIC curve at lower temperature common to I and 2 show very

MU)

t 22

I

20

I

2A Fig. 3. X-ra~ diffraction

I

30 /

I

I

deg patterns

I

40

I

50

(Cu K~) 10)

startiilg

psol’~cr’stallincSnS~sCnthesoed

it

rii,iterjals and

4(3(°U.

600

T Shihata et at.

/ Synthesi.s of single crystal SnS,

by CVT at LT using RTG

value 410.38. They are considered to be organic

Fig. Sb shows the mass spectra after the ten1perature reached 200°C, and shows identified

(organometallic) compounds in the initial material or to he adsorbed on the sample surface.

substances for the peaks. The peaks near 260, 225. 190 and 155, which are considered to he parents

complicated mass spectra with maximum M/z

I I

200

ill

680

800 Temperature / 01

1000

1200

1400

i~

~~~2O8V,

~

50

..~

...

—

I

I 200

I

400

I 800 Temperature / 08 I

600

1110

1210

1400

Fig. 4. Results of TG/DTA and I)TG of 1 (at and single cr~stalSnS, (6).

T. Shibata et aL

/ Synthesis

601

ofsingle crystal SnS, by CVT at LT using RTG

Retention Time / miD

100

0

5

10

i

I

I

15 I I

I

20

I

I

I

—~400 i

a80

—

—

Temp

300

—

60-200~ ~~0~~

~40

-

TIC —

20

0

I

i

100

200

—Q 700

I

300

400

500

100

i

600

Scan Hetentiee Time / mm

100

I

I

I

5 1

10 )

15 I

20

I

400

~

80 —

.~60

300

-

Temp.

—

~40

200~

-

—

20

100

TIC 0 I

0

100

200

300

400

500

600

—Q 700

Scan Fig. 5. TIC as a function of temperature of 1(a) and 2 (b), and the mass spectra of 1(c) at 2000 C.

are identified to be SnCl 4, 3~,respectively, accordSnCl~, SnCl~ and SnCl ing to the possible combination of isotope compoof

iI2~~

24Sn

to i

nentsdetected of Sn and Their3.peaks found inin 1,1,were not in Cl. 2 and Therefore, Sn vaporized as a chloride complex.

602

T. Shihata et al.

100

~

/ Srnthesi.s

o/ single crystal SnS~by (VT at LT using R TG

3nC)~

3~

~i:s~

SIIC)

. 04

32. 30

(55

40

C

90

Sr MS .1

20

0

L ‘J~ ~ I

50

100

150

200

250

380

M/ Fig. 1. (continued)

After the reaction, transparent crystals and yellow particles less than 3 mm3 in size were deposited at both sides of the quartz ampoules of 1. besides the yellow or colorless liquid by-products which were observed in the quartz tube walls. The yellow particles were found to he S by EPMA. ‘[lie transparent crystal was confirt1led to he (N 1—14) 2SnC’l ~, by several analytical methods: 4 I Sn h’~ and (‘1 were detected by EPMA and — NH I R spectral analysis. The crystal belongs to the cubic (Frn3m) crystal system with OIl = 10.06 A. as determined by X—ray diffraction analysis. TG/ DTA and IR data of the transparent crystal and the synthesized standard (NH 4)7SnCl~were identical. As for the yellow or colorless liquid by-products. they were found to he H2S (z = 2. 3. 4). Summarizing this series of the analytical resuIts, the (NH4 )2SnCI5, detected in the tube only after thermal the synthesis is supposed to he formed during reaction from NH 4CI and SnCI4. Sample I contains chloride of Sn and its crystalline water or adsorption water. From these results, the reasons why single crystal SnS2 was success— fully synthesized at low temperatLire are deduced

as follows. As the samples I are less stable due to lattice defects, they tend to decompose easier through the formation of chloride of Sn or hydragen chloride complex. The new species formed in the transport tone combines with free S to form SnS~in the growing zone at higher temperature. Furthermore. to confirm the above deduclion, it was tried to synthesize crystals1 svt~ from of 4 and 5 which were preparedsingle by adding

N H 4(1 by planetary mill to 2 and 3. and from 6 and 7 which were prepared h adding El ~O to 4 and 5 (breaking inside the vacuum an ampoLile including 25 gI pure water). Samples 8 and 9 were prepared by adding 0.036 g of Sn(’14 . 5H2() (Wako. reagent grade) to 2 and 3 respectively, and 10 and II by adding 0.07 ml of SnCI (Wako. reagent grade) to 2 and 3. respectively. result,~~ere innumerable crystals. 0.01 2Asina size. depositedsingle at low temperatures cm ( T~= 431- 44()0 C. 7/ == 465 4670 (1. hut did not grow in the case of 4 and 5. Similar resulls ssere obtained in another 5’~stem iii which we have added Sn(.’l 2 or (NH4 )-,Sn(l, to 2 and 3. Hossever, in contrast to the ground initial substance

T Shihata et al.

/

Synthesi.s of single crystal SnS, by C VT at LT using RTG

603

like 2 or 3, single crystals were not deposited when unground SnS2 single crystal (added impurities as

Acknowledgments

described above) was used as initial substance. It was found that the process of grinding was the necessary factor to synthesize single crystal SnS2. In 6 and 7, a distinctly larger volume of single crystal was obtained than in 4 and 5. In 8—Il (addition of chloride of Sn(IV)), more substrate was transported than in the other tubes. Innumerable crystals were grown, except for 10 where 30—40 pieces of well-grown crystals were obtained. Accordingly, the deduction stated above was proved to be correct. Sample 3 was easily decomposed to form many nuclei and therefore, many crystals of small size were formed; 2 was not too easily decomposed and fewer crystals of larger size than 3 were formed. However, they were strongly influenced by the amount of transport agent and subtly by the position of radial direction of the furnace. Therefore it was not clear which of the two, 2 or was more suitable as initial substance. For the determination of the structure of the intermediate product, further investigation in situ

The authors are grateful to Assistant Professor H. Hirashima and Mr. A. Sato for TG/DTA, to Professor T. Senna and Mr. T. Ikeya who allowed us to use the equipment for measurement of the particle size distribution, to Mr. T. Takeda for manufacturing the quartz tubes and to Professor E. Kaldis for correcting the English. The data on ICP were provided by Mr. H. Inoue of Soekawa Rikagaku Co., Ltd.

~,

is necessary.

4. Conclusion By grinding SnS2 polycrystals, the surface area of the prism face increases, and crystal lattice defects are introduced. These cause SnS2 to be in an activated state. Under these conditions, decomposition products of SnCI4 or SnCI4’ 5H20 act as transport agents of Sn, and, therefore, the growth of single crystal SnS2 by chemical vapor transport method at low temperature (< 450°C) becomes possible. Using (hydrogen) chloride, it is possible to transport gradually from low to high temperature corresponding to a reverse temperature profile. It is found that by this method, many single crystals of one of the largest volumes reported up to now can be obtained. A single crystal growth method, using unstable starting material and chloride as a transport agent, will be applied by us to other compounds, including layer-structured chalcogenide, in the near future.

References [1] G.H. Mob and B. Fritz, Neues Jahrh. Mineral., Monaish. 3 (1964) 94. [2] M. Fleischer, Am. Mineralogist 58 (1973) 347. [3] F.J. Landolt—Bornstein, Group III: Crystal and Schmiite. Solid StateIn: Physics, Vol. 17, Semiconductors, Eds. K-H. Hellwege and 0 Madetung (Springer, Berlin. 1983) ~. 204—208. 456—460. [4] T. Shibata. T. Miura. T. Kishi and T. Nagai. Denki Kagaku 57 (1989) 2125. [5] T. Shihata, Y. Muranushi, T. Miura and T. Kishi, Denki Kagaku 58 (1990) 269. 161 T. Shibata, Y. Muranushi. T. Miura and T. Kishi, Hyoumen Gijutu 40 (1989)1142. 17] B. Palosz. W. Palosz and S. Gierlotka, Acta Cryst. C41 (1985) 807. [8] B. Palosz, W. Palosz and S. Gierlotka. Bull. Mineral. 109 (1986) 143. [91R.S. Mitchell, Y. Fujiki and Y Ishizawa, Nature 247 (1974) 537. [10] JR. Guenter, HR. Oswald. Naturwissenschaften 55 (2968) 177. 1111 T. Minagawa, J. Phys. Soc. Japan 49J.(1980) 2317. [12] CR. Whitehouse and A.A. Balchin, Crystal Growth 47 (1979) 203. [13] H. Schafer. Chemical Transport Reactions (Academic Press, New York. 1964). [14] E. Kaldis. in: Crystal Growth, Theory and Techniques. Vol. 1, Ed. C.H.L. Goodman (Plenum, London. 1974). [15] MM. Faktor and I. Garrett. Growth of Crystals from the Vapour (Chapman and Hall, London. 1974). [16] H. Wiedemeier and F.J. Csillag, .1. Crystal Growth 46 (1979) 189.

[17] F.A.S. Al-Alamy and A.A. Balchin, J. Crystal Growth 38 221. Inorganic Synthesis 12 (1970) 158. [18] (1977) L.E. Conroy, [09] F. McTaggart and J Bear, J Australian J Chem. 11 (1958) 458. 1201 Ri. Nitsche, Phys. Chem. Solids 17 (1960) 163.

604

T. Shihata et a!.

/ Svnthesi,s ofsingle crystal

121] 1).L. Greenawas and R.J. Nitsche, Phys. Chem. Solids 26 (1965) 1445. [22] G.S. Said. PhD Thesis. Brighton Polytechnic (1971). [23] H.P.B. Rimmington. A.A. Balchin and BK. Tanner, J. Crystal Growth 15 (1972) 51. [24] H.P.B. Rimmington. PhD Thesis. Brighton Polytechnic (1973). 125] F.A.S. Al-Alamy and A.A. Balchin, Mater. Res. Bull. 8 (4973) 245. [26] G. Domingo. R.S. Itoga and CR. Kannewurf, Phys. Rev. 143 (1966) 536. [27] R. Nakata, M. Yamaguchi. S. Zembutsu and M. Sumita. J. Phys. Soc. Japan 32(1972)1153. [281 J. George and U.K. Valsala Kumari, J. Crystal Growth 63 (1983) 233. [29] PA. Lee. G. Said and R. Davis. Solid State Commun. 7 (1969) 1359. [3010. Said and PA. Lee, Phys. Status Solidi (a) 15 (1973) 99. [311 M.J. Po~elI,J. Phys. C (Solid State Phys.) 20(1977) 2967. 1321 S. Acharva and ON. Srivastava. Phys. Status Solidi (a) 56 (1979) KI. 1331 K. Matumoto. K. Takagi and S. Kaneko, J. Crystal Growth h3 (2983) 202.

SnS

2 hi, CVTut LTusing RTG

[34] R.S. Roth. T. Negas and L.P. (‘ook. Phase Diagrams for Ceramists. Vol. V (American Ceramic Society, 1983) pp. 276—278. [35] A.A. Blanhord, Synthetic Inorganic Chemistry (wiles. New York. 1936) pp. 271—273. [36] P. Woulfe. Phil. Trans. 61(1771)114. [37] J.W. Mellor, A Comprehensive Treaties on Inorganic and Theoretical Chemistry, Vol. 7 (Longmans. Green and Co.. London. 1927) p. 469. [38] F.A.S. Al-Alamy and A.A. Baichin, J. Crystal Growth 39 (1977) 275. [39] Ri. Nitsche. in: Crystal Growth, Ed. H.S. Peiser (Pergamon. Oxford. 1967) p. 215. [40] S.G. Patil and RH. Tredgold, J. Phys. D (AppI. Ploys.) 4 (1971)728. [41] S. Acharya and ON. Srivastava, Phvs. Status Solidi (a) 65 (1981) 717. [42] S. Nakashima. H. Katahama and A. Mitsuishi. Physica BIOS (1981) 343. [43] T. Shihata, A Study on Photo-Intercalated Metal Sulfide. Thesis. Kcio University. Yokohama (1985).