In a crystal growth furnace having an array of vertically arranged heaters to provide controlled heating zones within a chamber, and a crucible for holding crystal material, wherein the crystal is grown vertically through the heating zones, the improvement includes a laser mounted outside the chamber which radiates a beam of energy to locally melt precipitates and inclusions. The furnace includes a mechanism to position the laser vertically to, at or near the interface between the formed crystal and crystal melt material above the formed crystal. The crystal material can be CdZnTe.

In a crystal growth furnace having an array of vertically arranged heaters to provide controlled heating zones within a chamber, and a crucible for holding crystal material, wherein the crystal is grown vertically through the heating zones, the improvement includes a laser mounted outside the chamber which radiates a beam of energy to locally melt precipitates and inclusions. The furnace includes a mechanism to position the laser vertically to, at or near the interface between the formed crystal and crystal melt material above the formed crystal. The crystal material can be CdZnTe.

Provided is a method of preparing an SnSe thermoelectric material including (a) heating a mixture including Sn.sup.2+ and Se.sup.2−, (b) cooling the mixture at a cooling rate greater than 0 and equal to or less than 3 K/h, and forming single crystal Sn.sub.1-xSe (where 0<x<1), and an SnSe thermoelectric material prepared thereby and including Sn vacancies.

This disclosure provides an apparatus to manipulate the crystal morphology of a powder to improve the flow of a powder from a vessel and/or flowability of a powder in order to achieve stable fluidization of the powder within a vessel.

This disclosure provides an apparatus to manipulate the crystal morphology of a powder to improve the flow of a powder from a vessel and/or flowability of a powder in order to achieve stable fluidization of the powder within a vessel.

A method for preparing a large-size two-dimensional layered metal thiophosphate crystal includes the following steps: 1) weighing raw materials of indium spheres, phosphorous lumps and sulfur granules according to a predetermined amount and proportion, mixing them, and using iodine as a transport agent and potassium iodide as a molten salt; 2) adding the raw materials, the iodine and the potassium iodide to a reaction vessel together, and vacuum sealing it under a certain pressure, and then subjecting it to a high-temperature reaction; 3) taking out the products after the reaction, and washing the products to remove the residual iodine and potassium iodide and obtain large-size two-dimensional layered metal thiophosphate crystals. This method is simple and highly efficient.

A method for preparing a large-size two-dimensional layered metal thiophosphate crystal includes the following steps: 1) weighing raw materials of indium spheres, phosphorous lumps and sulfur granules according to a predetermined amount and proportion, mixing them, and using iodine as a transport agent and potassium iodide as a molten salt; 2) adding the raw materials, the iodine and the potassium iodide to a reaction vessel together, and vacuum sealing it under a certain pressure, and then subjecting it to a high-temperature reaction; 3) taking out the products after the reaction, and washing the products to remove the residual iodine and potassium iodide and obtain large-size two-dimensional layered metal thiophosphate crystals. This method is simple and highly efficient.

A method of performing HVPE heteroepitaxy comprises exposing a substrate to a carrier gas, a first precursor gas, a Group II/III element, and ternary-forming gasses (V/VI group precursor), to form a heteroepitaxial growth of a binary, ternary, and/or quaternary compound on the substrate; wherein the carrier gas is H.sub.2, wherein the first precursor gas is HCl, the Group II/III element comprises at least one of Zn, Cd, Hg, Al, Ga, and In; and wherein the ternary-forming gasses comprise at least two or more of AsH.sub.3 (arsine), PH.sub.3 (phosphine), H.sub.2Se (hydrogen selenide), H.sub.2Te (hydrogen telluride), SbH.sub.3 (hydrogen antimonide, or antimony tri-hydride, or stibine), H.sub.2S (hydrogen sulfide), NH.sub.3 (ammonia), and HF (hydrogen fluoride); flowing the carrier gas over the Group II/III element; exposing the substrate to the ternary-forming gasses in a predetermined ratio of first ternary-forming gas to second ternary-forming gas (1tf:2tf ratio); and changing the 1tf:2tf ratio over time.

An infrared non-linear optical crystal has the following molecular formula: A.sub.18X.sub.21Y.sub.6M.sub.48, in which A is Ba, Sr or Pb; X is Zn, Cd or Mn; Y is Ga, In or Al; and M is S, Se or Te. The crystal belongs to trigonal system and has space group R3. The crystal Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48 is a type I phase matching non-linear optical material, in a particle size range of 150˜210 μm, its powder frequency doubling intensity and the laser damage threshold are respectively 0.5 times and 28 times those of the commercial material AgGaS.sub.2. Other crystals have the same or similar structure and properties such as optical property. The infrared non-linear optical crystal of the present application has important prospects in military and civilian applications, and can be used in electro-optical countermeasures, resource detection, space antimissile and communications, etc.

An infrared non-linear optical crystal has the following molecular formula: A.sub.18X.sub.21Y.sub.6M.sub.48, in which A is Ba, Sr or Pb; X is Zn, Cd or Mn; Y is Ga, In or Al; and M is S, Se or Te. The crystal belongs to trigonal system and has space group R3. The crystal Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48 is a type I phase matching non-linear optical material, in a particle size range of 150˜210 μm, its powder frequency doubling intensity and the laser damage threshold are respectively 0.5 times and 28 times those of the commercial material AgGaS.sub.2. Other crystals have the same or similar structure and properties such as optical property. The infrared non-linear optical crystal of the present application has important prospects in military and civilian applications, and can be used in electro-optical countermeasures, resource detection, space antimissile and communications, etc.