# US 8,771,379 B2 · Crystal growth in solution under static conditions

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- Number: US 8,771,379 B2
- Document ID: US8771379B2
- Status: Granted
- Kind: B2
- Application number: 12/517,928
- Filed: 2007-12-03
- Published: 2011-06-16
- Granted: 2014-07-08
- Earliest claimed: 2006-12-06
- Assignees: Centre National de la Recherche Scientifique (CNRS)
- Applicants: Alain Jean Theodore Ibanez; Julien Raphael Zaccaro
- Inventors: Alain Jean Theodore Ibanez; Julien Raphael Zaccaro
- Web page: https://patentgrep.com/patent/US8771379B2

## CPC

- C30B 7/08: by cooling of the solution
- C30B 29/14: Phosphates
- C30B 35/00: Apparatus not otherwise provided for, specially adapted for the growth, production or after-treatment of single crystals or of a homogeneous polycrystalline material with defined structure
- Y10T 117/1024: for crystallization from liquid or supercritical state
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A method for growing crystals in solution is suitable for the rapid, controlled and effective preparation of crystals of large dimensions from a solution supersaturated with a compound. The crystal growth is carried out under static conditions. To do this: the growth is performed in a crystallization chamber kept at a constant temperature Tc, which chamber is in fluid communication with a saturation chamber at a temperature Ts, similarly constant and different from Tc, with solubility of the compound at the temperature Ts greater than the solubility of the compound at the temperature Tc. A continuous circulation of the solution between the crystallization and saturation chambers is established, thus maintaining a constant supersaturation rate within the crystallization chamber. Furthermore, the circulating solution is subjected to a treatment for eliminating and inhibiting the formation of aggregates, enabling the nucleation of parasitic crystallites to be inhibited.

## Claims

### Claim 1

A method of preparing a crystal based on a compound (C), by crystal growth in solution, the method comprising:
providing a crystallization system comprising:
a solution (S) supersaturated with said compound (C),
a crystallization chamber, in fluid communication with
a saturation chamber, said saturation chamber including a source of compound (C) in the form of a feeder substance;
maintaining a constant crystallization temperature (Tc) in the crystallization chamber and a constant saturation temperature (Ts) in the saturation chamber, wherein Tc is different from Ts and the solubility of the compound (C) in the solution (S) at the temperature Ts is greater than the solubility of the compound (C) in the solution (S) at the temperature Tc;
circulating solution (S) in a continuous flow circuit between the saturation chamber and the crystallization chamber, wherein the solution is circulated at a substantially constant flow rate; and
carrying out the crystal growth within the crystallization chamber, while maintaining the constant crystallization temperature Tc, the constant saturation temperature Ts, and the substantially constant flow rate, in order to maintain a constant rate of supersaturation within the crystallization chamber during the crystal growth.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the crystallization system further comprises an aggregation treatment element, the method further comprising treating the circulating solution with said aggregation treatment element to remove, or inhibit the formation of, aggregates in the solution.

### Claim 3 (depends on 2)

The method according to claim 2, wherein the treating the circulating solution comprises submitting the circulating solution (S) to ultrasound between the crystallization chamber and the saturation chamber.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the compound (C) has a solubility in the solution (S) which increases with an increase in temperature, and wherein the temperature Ts kept constant within the saturation chamber is higher than the temperature Tc kept constant within the crystallization chamber.

### Claim 5 (depends on 4)

The method according to claim 4, further comprising heating the circulating solution and treating the circulating solution with ultrasound, between the crystallization chamber and the saturation chamber, in order to remove, or inhibit the formation of, aggregates in the solution.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the compound (C) has a solubility within the solution (S) which increases with a decrease in temperature, and wherein the temperature Ts kept constant within the saturation chamber is lower than the temperature Tc kept constant within the crystallization chamber.

### Claim 7 (depends on 6)

The method according to claim 6, further comprising cooling the circulating solution and treating the circulating solution with ultrasound, between the crystallization chamber and the saturation chamber, in order to remove, or inhibit the formation of, aggregates in the solution.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the supersaturation rate kept constant within the crystallization chamber is greater than 10%.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the compound (C) is potassium diphosphate KH2PO4 (KDP) or potassium diphosphate in an at least partially deuterated form (DKPD).

### Claim 10 (depends on 9)

The method according to claim 9, wherein the temperature difference (Ts−Tc) between the saturation chamber and the crystallization chamber is between 2° C. and 30° C.

### Claim 11 (depends on 9)

The method according to claim 9, wherein the temperature difference (Ts−Tc) between the saturation chamber and the crystallization chamber is between 15° C. to 20° C.

### Claim 12 (depends on 1)

The method according to claim 1, wherein the Tc is maintained at a temperature below 40° C.

### Claim 13 (depends on 12)

The method of claim 12, wherein the Tc is maintained at a temperature below 30° C.

### Claim 14 (depends on 1)

A device for implementing the method of claim 1, comprising:
a crystallization chamber configured for growing the crystal in solution, said crystallization chamber comprising an inlet and an outlet;
a means for regulating the temperature of the crystallization chamber and for maintaining a substantially constant crystallization temperature Tc within the crystallization chamber;
a saturation chamber configured for placing the solution (S) in contact with an excess of solid solute, said saturation chamber comprising an inlet in fluid communication with the outlet of the crystallization chamber, and an outlet in fluid communication with the inlet of the crystallization chamber,
a means for regulating the temperature of the saturation chamber and for maintaining a substantially constant saturation temperature Ts within the saturation chamber distinct from Tc; and
a continuous circulation system configured to circulate the solution (S) at a substantially constant flow rate between the crystallization chamber and the saturation chamber, the flow being in a direction from the outlet of the saturation chamber towards the inlet of the crystallization chamber, and from the outlet of the crystallization chamber towards the inlet of the saturation chamber.

### Claim 15 (depends on 14)

The device according to claim 14, wherein the continuous circulation system further comprises an aggregation treatment element configured to treat the circulating solution to remove or inhibit the formation of aggregates in the solution.

### Claim 16 (depends on 15)

The device according to claim 15, wherein the aggregation treatment element comprises a means for sonicating the solution.

### Claim 17 (depends on 16)

The device according to claim 16, wherein the continuous circulation system further comprises a means for heating or cooling the circulating solution.

### Claim 18 (depends on 1)

The method according to claim 1, wherein the Tc and the Ts are each maintained at a constant temperature that varies over time by less than +/−0.1° C.

### Claim 19 (depends on 1)

The method according to claim 1, wherein the Tc and the Ts are each maintained at a constant temperature that varies over time by less than +/−0.01° C.

### Claim 20 (depends on 1)

The method according to claim 1, wherein the compound (C) comprises one or more doping element.

### Claim 21 (depends on 1)

The method according to claim 1, wherein the crystal is grown to a size having at least one dimension of 10 centimeters or more.

### Claim 22 (depends on 1)

The method according to claim 1, wherein the supersaturation rate kept constant within the crystallization chamber is at least 15% to 20%.

### Claim 23 (depends on 1)

The method according to claim 1, wherein the solid feeder substance is contained within the saturation chamber.