US3840347A - Method of producing cd(hg(scn)4)single crystals - Google Patents

Method of producing cd(hg(scn)4)single crystals Download PDF

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US3840347A
US3840347A US00229740A US22974072A US3840347A US 3840347 A US3840347 A US 3840347A US 00229740 A US00229740 A US 00229740A US 22974072 A US22974072 A US 22974072A US 3840347 A US3840347 A US 3840347A
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solution
ethanol
solvent system
concentration
percent
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US00229740A
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J Grabmaier
R Plattner
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Siemens AG
Siemens Corp
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Siemens Corp
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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B7/00—Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions

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  • the invention relates to methods of producing large single crystals and more particularly the methods of producing large cadmium-mercury tetrathiocyanate single crystals.
  • Cadmium-mercury tetrathiocyanate crystals are known to be useful for non-linear frequency conversion of laser light so as to provide a high degree of efficiency.
  • Suggestions have been proposed for growing such Cd [Hg (SCN) crystals from a solution in a silicic acid gel.
  • a disphenoid (i.e., bisphenoid) crystal form having maximum edge lengths of 3 to mm.
  • Such crystal shapes or forms are not suited for use in frequency conversion of laser light and such disphenoid crystals must be shaped, as by grinding, to useful forms.
  • the reformed crystals have an edge length of only 1 to 2 mm. Since the yield of a frequency conversion process increases with the square of the linear dimension of the crystal utilized, it is highly desirable to provide as large a crystal as possible.
  • the invention provides large cadmium-mercury tetrathiocyanate single crystals and relatively simple, straightforward methods of producing the same.
  • a super-saturated solution of cadmium-mercury tetrathiocyanate (Cd [Hg (SCN) is produced in a solvent comprising a mixture of water and alcohol and the Cd [Hg (SCNM crystallizes therefrom as a large single crystal.
  • a preferred alcohol is ethanol and a preferred solvent comprises a 77 percent ethanol concentration in water.
  • Such a preferred solvent is saturated with Cd [Hg (SCN)4] and the ethanol concentration is lowered,
  • FIG. 1 is a graphic illustration showing the relation between Cd [Hg (SCN) solubility and ethanol concentrations
  • FIG. 2 is a graphic illustration showing the relation between Cd [Hg (SCNM-solubility and temperature.
  • the invention generally comprises forming large single crystals of Cd [Hg (SCN)4] from a Cd [Hg (SCN),] supersaturated solution that includes a mixture of water and alcohol.
  • Ethanol is a preferred alcohol in the alcohol-water solvent system of the invention because of the high solubility of Cd [Hg (SCN) in an ethanol-water system, for example, the solubility of Cd [Hg (SCN).,] in an ethanol-water system having about a percent concentration of ethanol is about 73 grams/liter.
  • Other low boiling alcohols may also be used, such as methanol, propanol, etc., or mixtures thereof.
  • a solvent system is produced having an ethanol concentration of at least about 75 percent and not more than about 77 percent in water and this solvent system is then provided with an amount of Cd [Hg (SCN) sufficient to no more than completely saturate with the solvent system (i.e., at least saturate the solvent system).
  • the solvent system includes water-alcohol mixtures wherein the concentration of alcohol ranges from about 25 to about percent.
  • such a partially saturated or saturated Cd [Hg (SCN)i]-solvent solution is altered so that the concentration of for example ethanol is lowered, down to as low as about 25 percent so that a super-saturated solution is produced, and large single crystals of Cd [Hg (SCN),] crystallize therefrom.
  • such a partially saturated or saturated Cd [Hg SCN),]-solvent solution is altered so that the concentration of ethanol is increased, up to as high as about 95 percent sothat a super-saturated solution forms and relatively large single crystals of Cd [Hg (SCN) crystallize from such solution.
  • such a partially saturated or saturated Cd [Hg (SCNM-solvent solution is provided at an upper temperature of about 50 C. and then cooled down to a lower temperature of about 2 0 C. so
  • the super-saturation of a solution is achieved, for example, by removing the ethanol vapors that form above the solution, as by blowing such vapors away. This lowers the concentration of ethanol in the solvent and causes a decrease in the solubility of the crystallizing component in the solution so that crystallization of a desired large single crystal of Cd [Hg (SCNM takes place.
  • the super-saturation of the solution is achieved, for example, by subjecting the vapors above the solution with a water-absorbing substance, as a hydrophilic calcium or the like material so that the concentration of ethanol is increased in the solution.
  • a water-absorbing substance as a hydrophilic calcium or the like material
  • the solubility ofCd [Hg (SCN) is decreased so that the crystallization of a desired large single crystal of Cd [Hg (SCN) takes place.
  • the crystallization of Cd [Hg (SCN) is effected at temperatures of about 20 C. It is particu- 3 larly advantageous to provide a super-saturated solution of the type described at about 50 C. and then cool it down to about 20 C. since the solubility of Cd [Hg (SCNM is lower at 20 C. than at 50 C. so that as large as possible single crystals are produced. However. temperatures above 50 C. cause a small amount of decomposition of Cd [Hg (SCN) over a period of some weeks (which is required for proper growth) and are thus to be avoided.
  • FIG. 1 illustrates the quantitative relation between the solubility ofCd [Hg (SCN) and the concentration of ethanol in water, at 204 C.
  • the solubility of Cd [Hg (SCN) in'ethanol-water solutions having an ethanol concentration ranging from about 25 to about 75 C. increases drastically upwards from about 5g/l with increases in ethanol concentration and reaches a maximum in a solution having about a 77 percent ethanol concentration.
  • the solubility of Cd [Hg (SCN) in solvent solutions having about 77 percent ethanol therein is about 73 grams/liter.
  • solvent solutions having ethanol concentrations ranging from about 77 to about 95 percent the solubility of Cd [Hg (SCN) decreases substantially with increased concentrations of ethanol.
  • At least about 5 g/l of Cd[Hg(SCN) are added to an alcohol-water solvent system and the concentration of one of the solvent components (alcohol or water) is changed so as to decrease the solubility of Cd[Hg(SCN) in the resulding system and cause large single crystals of Cd[Hg(SCN) to form.
  • initial alcohol-water solvent systems having an alcohol concentration in the range of about at least 25 percent and up to about 77 percent, the alcohol concentration is decreased below that in such initial solvent systems.
  • the initial alcohol-water solvent systems having an alcohol concentration in the range of about at least 77 percent and up'to about 95 percent, the alcohol concentration is increased above that in such initial solvent systems.
  • a controllable super-saturation is obtained when the ethanol v concentration is increased from about 77 to about 95 percent (or the concentration of water is decreased correspondingly) as illustrated on the right hand side of the graph at FIG. 1, starting at the v maximum point of solubility.
  • Increases in the ethanol concentration or decreases in the water concentration are readily achieved by treating the vapor above the solution with a water-removing substance or by removing water from the solution itself.
  • Super-saturation of the solution is also achieved by slowly adding pure water or pure alcohol to the solution.
  • an ethanol-water mixture with an, ethanol con- 4 centration less than 77 percent is provided by additions of pure water and in another form, an ethanol-water mixture with an ethanol concentration greater than 77 percent is provided by additions of pure ethanol.
  • a means of achieving super-saturationother than by changing the ethanol-water mixture ratio is by lowering the solubility of Cd [Hg(SCN) in the ethanol-water mixture through a decrease in the solution temperature.
  • the relation between the solubility of Cd [Hg (SCN) and temperature is illustrated at FIG. 2. in accordance with theprinciples of the invention as illustrated at FIG. 2, at least about 5 g/l of Cd[Hg(SCN) are added to an alcohol-water system which is maintained at about 50 C. so as to form a solution of the tetrathiocyanate in the solvent system and then the resulting solution is cooled to a temperature of about 20 C.
  • the saturated or partially saturated solution is produced at a temperature of about 50 C. and then cooled to about 20 C. for crystallization therefrom of a desired relatively large single crystal.
  • a minor disadvantage of this embodiment is that Cd [Hg (SCN) in a solution with a temperature over 50 C. tends to slightly decompose and in a few days under such conditions, the solution becomes a pale yellow and gives rise to the possibility-of contamination in crystals obtained therefrom.
  • the invention broadly provides a method of producing cadmium-mercurytetrathiocyanate single crystals by forming a saturated or a supersaturated solution of cadmium-mercury tetrathiocyanate in a solvent comprising a mixture of alcohol and water and crystallizing the cadmium-mercury tetrathiocyanate therefrom as a relatively large single crystal.
  • a method of producing cadmium-mercury tetrathiocyanate single crystals comprising:
  • a method as defined in claim 2 wherein changing the concentration of one of said solvent components comprises removing an amount of a solvent component until said resultant solution is obtained.
  • changing the concentration of one of said solvent components comprises adding an amount of a solvent component until said resultant solution is obtained.
  • a method of producing cadmium-mercury tetrathiocyanate single crystals comprising:. 7

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
US00229740A 1971-03-04 1972-02-28 Method of producing cd(hg(scn)4)single crystals Expired - Lifetime US3840347A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2110425A DE2110425C3 (de) 1971-03-04 1971-03-04 Verfahren zur Herstellung von Cadmium Quecksilber Tetrathiocyanat Einkristallen aus wässrig alkoholischer Losung

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US3840347A true US3840347A (en) 1974-10-08

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US (1) US3840347A (cg-RX-API-DMAC10.html)
BE (1) BE780215A (cg-RX-API-DMAC10.html)
DE (1) DE2110425C3 (cg-RX-API-DMAC10.html)
FR (1) FR2128392B1 (cg-RX-API-DMAC10.html)
GB (1) GB1331900A (cg-RX-API-DMAC10.html)
IT (1) IT953460B (cg-RX-API-DMAC10.html)
LU (1) LU64886A1 (cg-RX-API-DMAC10.html)
NL (1) NL7202858A (cg-RX-API-DMAC10.html)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4041323A (en) * 1970-03-20 1977-08-09 Siemens Aktiengesellschaft Non-linear optical frequency doubling devices

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4041323A (en) * 1970-03-20 1977-08-09 Siemens Aktiengesellschaft Non-linear optical frequency doubling devices

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Publication number Publication date
DE2110425A1 (de) 1972-09-21
FR2128392B1 (cg-RX-API-DMAC10.html) 1975-03-21
FR2128392A1 (cg-RX-API-DMAC10.html) 1972-10-20
DE2110425B2 (de) 1973-05-10
LU64886A1 (cg-RX-API-DMAC10.html) 1972-07-06
GB1331900A (en) 1973-09-26
DE2110425C3 (de) 1973-12-06
NL7202858A (cg-RX-API-DMAC10.html) 1972-09-06
IT953460B (it) 1973-08-10
BE780215A (fr) 1972-07-03

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