An oxychloride infrared nonlinear optical crystal and the preparation method and use thereof, the optical crystal has a general chemical formula of Pb.sub.2+xOCl.sub.2+2x, therein 0<x<0.139 or 0.141<x<0.159 or 0.161<x0.6. The crystal is non-centrosymmetric, belongs to orthonormal system with space group of Fmm2, cell parameter is a=35.4963(14)0.05 , b=5.8320(2)0.05 , c=16.0912(6)0.05 . The crystal is prepared by high temperature melt method or flux method. The crystal has a strong second harmonic generation efficiency of 4 times that of KDP (KH.sub.2PO.sub.4) tested by Kurtz method, it is phase machable, transparent in the range of 0.34-7 m. The laser damage threshold is 10 times that of the current commercial infrared nonlinear optical crystal AgGaS.sub.2. No crystalline water exists in lead oxychloride, and it is stable in the air and has good thermal stability.

An oxychloride infrared nonlinear optical crystal and the preparation method and use thereof, the optical crystal has a general chemical formula of Pb.sub.2+xOCl.sub.2+2x, therein 0<x<0.139 or 0.141<x<0.159 or 0.161<x0.6. The crystal is non-centrosymmetric, belongs to orthonormal system with space group of Fmm2, cell parameter is a=35.4963(14)0.05 , b=5.8320(2)0.05 , c=16.0912(6)0.05 . The crystal is prepared by high temperature melt method or flux method. The crystal has a strong second harmonic generation efficiency of 4 times that of KDP (KH.sub.2PO.sub.4) tested by Kurtz method, it is phase machable, transparent in the range of 0.34-7 m. The laser damage threshold is 10 times that of the current commercial infrared nonlinear optical crystal AgGaS.sub.2. No crystalline water exists in lead oxychloride, and it is stable in the air and has good thermal stability.

A SiC single crystal is prepared by the solution process of placing a seed crystal in contact with a SiC solution in a crucible and letting a SiC single crystal to grow from the seed crystal. The method includes the first growth step of conducting crystal growth using (0001) or (000-1) plane of a SiC single crystal of which the seed crystal is composed, as the growth surface, and the second growth step of conducting crystal growth using (1-100) or (11-20) plane of a SiC single crystal resulting from the first growth step as the growth surface. A SiC single crystal of high homogeneity and quality is obtained, which is reduced in threading screw dislocations, threading edge dislocations, basal plane dislocations, micropipes, and stacking faults.

A SiC single crystal is prepared by the solution process of placing a seed crystal in contact with a SiC solution in a crucible and letting a SiC single crystal to grow from the seed crystal. The method includes the first growth step of conducting crystal growth using (0001) or (000-1) plane of a SiC single crystal of which the seed crystal is composed, as the growth surface, and the second growth step of conducting crystal growth using (1-100) or (11-20) plane of a SiC single crystal resulting from the first growth step as the growth surface. A SiC single crystal of high homogeneity and quality is obtained, which is reduced in threading screw dislocations, threading edge dislocations, basal plane dislocations, micropipes, and stacking faults.

The present disclosure relates to a silicon-based fusion composition used for a solution growth method for forming a silicon carbide single crystal, and represented by the following Formula 1, including silicon, a first metal (M1), scandium (Sc) and aluminum (Al):

Si.sub.aM1.sub.bSc.sub.cAl.sub.d(Formula 1) wherein a is more than 0.4 and less than 0.8, b is more than 0.2 and less than 0.6, c is more than 0.01 and less than 0.1, and d is more than 0.01 and less than 0.1.

A low-resistance p-type SiC single crystal containing no inclusions is provided. A method for producing a SiC single crystal in which a SiC seed crystal substrate is contacted with a SiC solution having a temperature gradient such that a temperature of the SiC solution decreases from an interior of the SiC solution toward a surface of the SiC solution, to grow the SiC single crystal, wherein the SiC solution comprises Si, Cr, Al and B, and wherein the Al is comprised in the SiC solution in an amount of 10 at % or greater, based on the total of the Si, Cr, Al and B, and the B is comprised in the SiC solution in an amount of greater than 0.00 at % and no greater than 1.00 at %, based on the total of the Si, Cr, Al and B.

A method of producing a crystal includes a step of preparing a solution containing carbon and a silicon solvent, and a seed crystal of silicon carbide; a step of contacting a lower face of the seed crystal with the solution; a step of raising a temperature of the solution to a first temperature zone; a step of relatively elevating the seed crystal with respect to the solution in a state where a temperature of the solution is being lowered from the first temperature zone to a second temperature zone; a step of raising a temperature of the solution from the second temperature zone to the first temperature zone; and a step of relatively elevating the seed crystal with respect to the solution in a state where a temperature of the solution is being lowered from the first temperature zone to the second temperature zone.

A method of producing a crystal includes a step of preparing a solution containing carbon and a silicon solvent, and a seed crystal of silicon carbide; a step of contacting a lower face of the seed crystal with the solution; a step of raising a temperature of the solution to a first temperature zone; a step of relatively elevating the seed crystal with respect to the solution in a state where a temperature of the solution is being lowered from the first temperature zone to a second temperature zone; a step of raising a temperature of the solution from the second temperature zone to the first temperature zone; and a step of relatively elevating the seed crystal with respect to the solution in a state where a temperature of the solution is being lowered from the first temperature zone to the second temperature zone.

The disclosure relates to a semimetal compound of Pt and a method for making the same. The semimetal compound is a single crystal material of PtSe.sub.2. The method comprises: providing a PtSe.sub.2 polycrystalline material; placing the PtSe.sub.2 polycrystalline material in a reacting chamber; placing chemical transport medium in the reacting chamber; evacuating the reacting chamber to be vacuum less than 10 Pa; placing the reacting chamber at a temperature gradient, wherein the reacting chamber has a first end at a temperature of 1200 degrees Celsius to 1000 degrees Celsius and a second end opposite to the first end and at a temperature of 1000 degrees Celsius to 900 degrees Celsius; and keeping the reacting chamber in the temperature gradient for 10 days to 30 days.

The disclosure relates to a semimetal compound of Pt and a method for making the same. The semimetal compound is a single crystal material of PtSe.sub.2. The method comprises: providing a PtSe.sub.2 polycrystalline material; placing the PtSe.sub.2 polycrystalline material in a reacting chamber; placing chemical transport medium in the reacting chamber; evacuating the reacting chamber to be vacuum less than 10 Pa; placing the reacting chamber at a temperature gradient, wherein the reacting chamber has a first end at a temperature of 1200 degrees Celsius to 1000 degrees Celsius and a second end opposite to the first end and at a temperature of 1000 degrees Celsius to 900 degrees Celsius; and keeping the reacting chamber in the temperature gradient for 10 days to 30 days.