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Growth of single crystals from solutions using semi-permeable membranes
Journal of Crystal Growth 61(1983) 701—704 North-Holland Publishing Company
701
LETFER TO THE EDITORS GROWTH OF SINGLE CRYSTALS FROM SOLUTIONS USING SEMI-PERMEABLE MEMBRANES * A.J. VARKEY and C.E. OKEKE Department of Physics and Astronomy, University of Nigeria, Nsukka, Nigeria Received 18 April 1982; manuscript received in final form 20 December 1982
A technique suitable for growth of single crystals from solutions using semi-permeable membranes is described. Using this technique single crystals of copper sulphate, potassium bromide and ammonium dihydrogen phosphate have been successfully grown. Advantages of this technique over other methods are discussed.
Growth of single crystals from saturated solutions has been of great interest to workers in this field. Various techniques have been employed for different substances [1,2]. Slow cooling [3—7]and evaporation [2,8,9] are commonly used to supersaturate aqueous solutions for growth of large ideal [10] single crystals. We have developed a new and comparatively simple method for growing crystals from aqueous solutions using semi-permeable membranes. The present paper describes the experimental procedure used to supersaturate a saturated solution prepared at room temperature in order to facilitate growth when the solution is seeded. We discuss the growth rates of crystals grown by this technique and by the evaporation method, We first carried out an experiment to determine
perature. This vessel was placed in a larger glass container and the space between the walls was filled with finely divided solute. The vessel is air tight to minimize evaporation. A glass vessel of the same size and shape is also filled with solution to the same height and left open so that evaporation can easily occur. Within a few hours the level of the solution inside the membrane dropped sharply indicating that the semi-permeable membrane selectively let through the solvent but not the solute. No noticeable change occurred in the second vessel during this time indicating that the saturation by diffusion was much more rapid than by evaporation. The experimental configuration for crystal growth is shown in fig. 2. The cellophane vessel contained a saturated solution of CuSO4 5H20 in
whether a supersaturated solution could be produced by separating the solution from excess solute using a semi-permeable membrane, and also to compare the rate of supersaturation with the rate produced by the evaporation of a solution under the same conditions. The experimental setup for this experiment is shown in fig. 1. A vessel made of cellophane paper is filled with a saturated solution of CuSO4 5H2O prepared at room tern-
distilled water. The solution was filtered prior to placing into the cellophane. A 3 mm crystal of the same material (obtained by cooling a saturated solution at 50°C)was used as seed. The seed was suspended on a string. As before, the air-tight vessel was placed inside the finely divided solute material. After two days a crystal nearly 1.5 cm long was obtained, as shown in fig. 3b. A few spurious crystals were formed at the bottom of the vessel and on the string. A crystal grown from a 3 mm seed using the evaporation method is shown in fig. 3a. After 15 days this crystal grew to 3.5 cm. The longer growth time was required due to the
.
*
Work supported in part by a Senate Research Grant, University of Nigeria, Nsukka, Grant No. 00305/79.
0022-0248/83/0000--0000/$03.00
©
1983 North-Holland
~CIosed air tight —
Cellophone paper
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—
_.
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—---——_-_————-,,/
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ITTII±IITTilT Till
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I Ti
______.__
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Fig. I. Comparison of supersaturation rates.
Pa
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:~:LI~1~T_
~lIophane
_______________________________
_____________________________________
Fig. 2. Set-up for crystal growth.
/i~
Saturated Cu So4 solution
A.J. Varkey, C. E. Okeke
/
Growth ofsingle crystals from solutions using membranes
703
_~ab
Fig. 3. (a) CuSO
4 crystal grown by evaporation in 15 days. (b) CuSO4 crystal grown using a membrane in 2 days. Magnification 1.6 X.
slower growth rate. This crystal shows evidence of a nonuniform growth rate along its growth faces, unlike the crystal grown using the membrane. This could be explained as follows: Supersaturation of the solution inside the membrane takes place equally on all sides. Thus, there is a steady supersaturation everywhere on the growing crystal surface for all crystal orientations. In the evaporation method this does not occur as the removal of the solvent occurs only at the surface—air interface with supersaturations occurring only there. More uniform growth can be produced by rotation of the seed or stirring in the case of the evaporation method. The membrane system is thus both more rapid and simpler. Two crystals of ammonium dihydrogen phosphate (ADP) grown by this technique are shown in fig. 4. Both were grown under the same conditions and have uniformly developed growth planes. Potassium bromide was also grown using both the membrane and evaporation technique. Saturated solutions of the same volume and concentration contained in an uncovered glass vessel and in
a covered cellophane vessel, were seeded and left undisturbed for two days. The results are shown in fig. 5. Figs. 5a and Sb show crystals grown in the
,-
-~
Fig. 4. Crystals of ammonium dihydrogen phosphate grown using a membrane. Magnification 0.6 x.
704
A .J. Varkey, C. E. Okeke
/ Growth
of single crystals from solutions using membranes
be obtained without stirring or rotating the seed due to a more uniform solution concentration. The method is both simple and more rapid than
a
crystal crystallization growth by evaporation. at thebybottom Some ofRotation thespurious vessel, which might beoccurs eliminated stirring. of the seed, stirring and the use of high purity solutions are being tried. It is hoped that this method
b
can References be utilized theGrowth growth(Wiley, of other materials. [I] HE. Buckley, for Crystal London, 1951).
Fig. 5. (a) Crystal of KBr grown on the string. (b) Crystal of KBr grown on a seed of the same size as (c) using a membrane (after two days). (c) Seed of KBr on which no growth occurred in a glass vessel. Magnification 1.4 X.
[2] G.F. Reynolds, in: Physics and Chemistry of the Organic Solid State, Vol. 1, Eds. D. Fox, M.M. Labes and A. Weissberger (Wiley-.Jnterscience, New York, 1963). [3] L.N. Matusevich, in: Growth of Crystals, Vol. I, Eds. A.V. Shubnikov and N.N. Sheftal (Consultants Bureau, New York, 1959) p. 168. [4] A.A. Chumakov. in: Growth of Crystals, Vol. 2, Eds. A.V. Shubnikov and N.N. Sheftal (Consultants Bureau, New York, 1959) pp. 82—85. [5] S. Sang, CL. Leci and N. Eidelman, J. Crystal Growth 47 (1979) 365. [6] W.J.P. van Enckevort and W.H. van der Linden, J. Crystal Growth 47 (1979) 196.
[7~ M. Ribet, J.L. Ribet, F. Lefaucheux and M.C. Robert, J.
cellophane vessel. Practically no growth occurred in the uncovered glass vessel (fig. Sc). No actual growth rate studies were performed. In summary, semi-permeable membranes can be used to supersaturate a saturated solution for growing single crystals. This has the advantage over evaporation in that more perfect crystals can
Crystal Growth 49 (1980) 334. [8] M Matsunaka, M. Kitamura and I. Sunagawa. J Crystal Growth 48 (1980) 425. [9] K. Sato, S. Hashimoto and M. Okada. J. Crystal Growth 49 (1980) 665. [10] C. Bunn, Crystals, Their Role in Nature and in Science (Academic Press, New York, 1964) p. 99.
701
LETFER TO THE EDITORS GROWTH OF SINGLE CRYSTALS FROM SOLUTIONS USING SEMI-PERMEABLE MEMBRANES * A.J. VARKEY and C.E. OKEKE Department of Physics and Astronomy, University of Nigeria, Nsukka, Nigeria Received 18 April 1982; manuscript received in final form 20 December 1982
A technique suitable for growth of single crystals from solutions using semi-permeable membranes is described. Using this technique single crystals of copper sulphate, potassium bromide and ammonium dihydrogen phosphate have been successfully grown. Advantages of this technique over other methods are discussed.
Growth of single crystals from saturated solutions has been of great interest to workers in this field. Various techniques have been employed for different substances [1,2]. Slow cooling [3—7]and evaporation [2,8,9] are commonly used to supersaturate aqueous solutions for growth of large ideal [10] single crystals. We have developed a new and comparatively simple method for growing crystals from aqueous solutions using semi-permeable membranes. The present paper describes the experimental procedure used to supersaturate a saturated solution prepared at room temperature in order to facilitate growth when the solution is seeded. We discuss the growth rates of crystals grown by this technique and by the evaporation method, We first carried out an experiment to determine
perature. This vessel was placed in a larger glass container and the space between the walls was filled with finely divided solute. The vessel is air tight to minimize evaporation. A glass vessel of the same size and shape is also filled with solution to the same height and left open so that evaporation can easily occur. Within a few hours the level of the solution inside the membrane dropped sharply indicating that the semi-permeable membrane selectively let through the solvent but not the solute. No noticeable change occurred in the second vessel during this time indicating that the saturation by diffusion was much more rapid than by evaporation. The experimental configuration for crystal growth is shown in fig. 2. The cellophane vessel contained a saturated solution of CuSO4 5H20 in
whether a supersaturated solution could be produced by separating the solution from excess solute using a semi-permeable membrane, and also to compare the rate of supersaturation with the rate produced by the evaporation of a solution under the same conditions. The experimental setup for this experiment is shown in fig. 1. A vessel made of cellophane paper is filled with a saturated solution of CuSO4 5H2O prepared at room tern-
distilled water. The solution was filtered prior to placing into the cellophane. A 3 mm crystal of the same material (obtained by cooling a saturated solution at 50°C)was used as seed. The seed was suspended on a string. As before, the air-tight vessel was placed inside the finely divided solute material. After two days a crystal nearly 1.5 cm long was obtained, as shown in fig. 3b. A few spurious crystals were formed at the bottom of the vessel and on the string. A crystal grown from a 3 mm seed using the evaporation method is shown in fig. 3a. After 15 days this crystal grew to 3.5 cm. The longer growth time was required due to the
.
*
Work supported in part by a Senate Research Grant, University of Nigeria, Nsukka, Grant No. 00305/79.
0022-0248/83/0000--0000/$03.00
©
1983 North-Holland
~CIosed air tight —
Cellophone paper
,~,/—
Open
~~_-Glass
—
Powdered— solute
—
_.
_..._
—
—---——_-_————-,,/
2 /
ITTII±IITTilT Till
/
I Ti
______.__
—
/
—
IliTiTiTiTi
/7/
—
—
ii
—
//////////Mø/ Saturated Cu
So
4 solution
Fig. I. Comparison of supersaturation rates.
Pa
0 /4
:~:LI~1~T_
~lIophane
_______________________________
_____________________________________
Fig. 2. Set-up for crystal growth.
/i~
Saturated Cu So4 solution
A.J. Varkey, C. E. Okeke
/
Growth ofsingle crystals from solutions using membranes
703
_~ab
Fig. 3. (a) CuSO
4 crystal grown by evaporation in 15 days. (b) CuSO4 crystal grown using a membrane in 2 days. Magnification 1.6 X.
slower growth rate. This crystal shows evidence of a nonuniform growth rate along its growth faces, unlike the crystal grown using the membrane. This could be explained as follows: Supersaturation of the solution inside the membrane takes place equally on all sides. Thus, there is a steady supersaturation everywhere on the growing crystal surface for all crystal orientations. In the evaporation method this does not occur as the removal of the solvent occurs only at the surface—air interface with supersaturations occurring only there. More uniform growth can be produced by rotation of the seed or stirring in the case of the evaporation method. The membrane system is thus both more rapid and simpler. Two crystals of ammonium dihydrogen phosphate (ADP) grown by this technique are shown in fig. 4. Both were grown under the same conditions and have uniformly developed growth planes. Potassium bromide was also grown using both the membrane and evaporation technique. Saturated solutions of the same volume and concentration contained in an uncovered glass vessel and in
a covered cellophane vessel, were seeded and left undisturbed for two days. The results are shown in fig. 5. Figs. 5a and Sb show crystals grown in the
,-
-~
Fig. 4. Crystals of ammonium dihydrogen phosphate grown using a membrane. Magnification 0.6 x.
704
A .J. Varkey, C. E. Okeke
/ Growth
of single crystals from solutions using membranes
be obtained without stirring or rotating the seed due to a more uniform solution concentration. The method is both simple and more rapid than
a
crystal crystallization growth by evaporation. at thebybottom Some ofRotation thespurious vessel, which might beoccurs eliminated stirring. of the seed, stirring and the use of high purity solutions are being tried. It is hoped that this method
b
can References be utilized theGrowth growth(Wiley, of other materials. [I] HE. Buckley, for Crystal London, 1951).
Fig. 5. (a) Crystal of KBr grown on the string. (b) Crystal of KBr grown on a seed of the same size as (c) using a membrane (after two days). (c) Seed of KBr on which no growth occurred in a glass vessel. Magnification 1.4 X.
[2] G.F. Reynolds, in: Physics and Chemistry of the Organic Solid State, Vol. 1, Eds. D. Fox, M.M. Labes and A. Weissberger (Wiley-.Jnterscience, New York, 1963). [3] L.N. Matusevich, in: Growth of Crystals, Vol. I, Eds. A.V. Shubnikov and N.N. Sheftal (Consultants Bureau, New York, 1959) p. 168. [4] A.A. Chumakov. in: Growth of Crystals, Vol. 2, Eds. A.V. Shubnikov and N.N. Sheftal (Consultants Bureau, New York, 1959) pp. 82—85. [5] S. Sang, CL. Leci and N. Eidelman, J. Crystal Growth 47 (1979) 365. [6] W.J.P. van Enckevort and W.H. van der Linden, J. Crystal Growth 47 (1979) 196.
[7~ M. Ribet, J.L. Ribet, F. Lefaucheux and M.C. Robert, J.
cellophane vessel. Practically no growth occurred in the uncovered glass vessel (fig. Sc). No actual growth rate studies were performed. In summary, semi-permeable membranes can be used to supersaturate a saturated solution for growing single crystals. This has the advantage over evaporation in that more perfect crystals can
Crystal Growth 49 (1980) 334. [8] M Matsunaka, M. Kitamura and I. Sunagawa. J Crystal Growth 48 (1980) 425. [9] K. Sato, S. Hashimoto and M. Okada. J. Crystal Growth 49 (1980) 665. [10] C. Bunn, Crystals, Their Role in Nature and in Science (Academic Press, New York, 1964) p. 99.