In a method for manufacturing a group 13 nitride crystal, a seed crystal made of a group 13 nitride crystal is arranged in a mixed melt containing an alkali metal and a group 13 element, and nitrogen is supplied to the mixed melt to grow the group 13 nitride crystal on a principal plane of the seed crystal. The seed crystal is manufactured by vapor phase epitaxy. At least a part of contact members coming into contact with the mixed melt in a reaction vessel accommodating the mixed melt is made of Al.sub.2O.sub.3. An interface layer having a photoluminescence emission peak whose wavelength is longer than the wavelength of a photoluminescence emission peak of the grown group 13 nitride crystal is formed between the seed crystal and the grown group nitride crystal.

A calcium metaborate birefringent crystal and a preparation method and use thereof, the crystal having a chemical formula of CaB.sub.2O.sub.4 and a molecular weight of 125.70, and belonging to the orthorhombic crystal system and space group Pbcn with unit-cell parameters a=11.60(4), b=4.28(8), c=6.21(6), and Z=4, wherein the calcium metaborate birefringent crystal is a negative biaxial crystal with a transmission range of 165-3400 nm and a birefringence between 0.09-0.36; the crystal is applicable to infrared-visible-ultraviolet-deep ultraviolet bands, and is grown by a melt method, a flux method, a Bridgman method or a heat exchange method; the crystal obtained by the method of the present invention is easy to grow and easy to process; and can be used for making polarizing beam-splitting prisms.

A calcium metaborate birefringent crystal and a preparation method and use thereof, the crystal having a chemical formula of CaB.sub.2O.sub.4 and a molecular weight of 125.70, and belonging to the orthorhombic crystal system and space group Pbcn with unit-cell parameters a=11.60(4), b=4.28(8), c=6.21(6), and Z=4, wherein the calcium metaborate birefringent crystal is a negative biaxial crystal with a transmission range of 165-3400 nm and a birefringence between 0.09-0.36; the crystal is applicable to infrared-visible-ultraviolet-deep ultraviolet bands, and is grown by a melt method, a flux method, a Bridgman method or a heat exchange method; the crystal obtained by the method of the present invention is easy to grow and easy to process; and can be used for making polarizing beam-splitting prisms.

Crystalline NH.sub.4Be.sub.2BO.sub.3F.sub.2 or Be.sub.2BO.sub.3F (abbreviated as BBF) has nonlinear optical effect, is not deliquescent in the air, is chemically stable. They can be used in a variety of nonlinear optical fields and will pioneer the nonlinear optical applications in the deep UV band.

Crystalline NH.sub.4Be.sub.2BO.sub.3F.sub.2 or Be.sub.2BO.sub.3F (abbreviated as BBF) has nonlinear optical effect, is not deliquescent in the air, is chemically stable. They can be used in a variety of nonlinear optical fields and will pioneer the nonlinear optical applications in the deep UV band.

The invention relates to a lithium metaborate crystal and a preparation method and use thereof. The crystal has a chemical formula of LiBO.sub.2, a molecular weight of 49.75, and is a member of the monoclinic crystal system. The crystal has a P2.sub.1/c space group and lattice constants of a=5.85(8) , b=4.35(7) , c=6.46(6) , =115(5) I, and Z=4. The crystal can be applied in wavelengths of infrared-visible-deep ultraviolet, and is grown by utilizing a melt crystallization method or a flux method. The crystal obtained using the method described in the invention is easily grown and processed, and can be used in the manufacture of a polarizing beam splitting prism such as a Glan prism, a Wollaston prism, a Rochon prism or a beam-splitting polarizer, and other optical components, enabling crucial applications in the fields of optics and communication.

The invention relates to a lithium metaborate crystal and a preparation method and use thereof. The crystal has a chemical formula of LiBO.sub.2, a molecular weight of 49.75, and is a member of the monoclinic crystal system. The crystal has a P2.sub.1/c space group and lattice constants of a=5.85(8) , b=4.35(7) , c=6.46(6) , =115(5) I, and Z=4. The crystal can be applied in wavelengths of infrared-visible-deep ultraviolet, and is grown by utilizing a melt crystallization method or a flux method. The crystal obtained using the method described in the invention is easily grown and processed, and can be used in the manufacture of a polarizing beam splitting prism such as a Glan prism, a Wollaston prism, a Rochon prism or a beam-splitting polarizer, and other optical components, enabling crucial applications in the fields of optics and communication.

An alumina substrate on which an AlN layer is formed and that causes less warping, and a substrate material strong enough to withstand normal handling when an AlN crystal is grown upon it, and prevents cracking and fracturing of a grown crystal when stress is applied during growing or cooling. The substrate has a gap and a rare earth element-containing region inside the AlN layer or at the interface between the AlN layer and the alumina substrate. Warping of the AlN layer can be reduced by lattice-mismatch stress being concentrated at the region and releasing of stress by the gap. The region having a concentrating of stress, and the gap having a low mechanical strength, can induce crackings and fracturings. As a result, contamination of crackings and fracturings into the crystal grown on the substrate can be prevented. The region can ensure a level of mechanical strength sufficient for handling.

Single crystals of the new semiconducting oxychalcogenide phase were synthesized using a novel crystal growth method. The crystals had low defects and homogeneous composition as characterized by single crystal X-ray diffraction and scanning electron microscopy, respectively. Heat capacity and resistivity measurements were in agreement with the calculated band structure calculations indicating semiconductivity, with a band gap of about 3 eV.

Single crystals of the new semiconducting oxychalcogenide phase were synthesized using a novel crystal growth method. The crystals had low defects and homogeneous composition as characterized by single crystal X-ray diffraction and scanning electron microscopy, respectively. Heat capacity and resistivity measurements were in agreement with the calculated band structure calculations indicating semiconductivity, with a band gap of about 3 eV.