Study On A New Infrared Nonlinear Optical Crystral CsGeBr₃

With development of science and technology and popularization of the infrared crystal stuff, the performance to the infrared crystal stuff was proposed more and more tall demand. It is so important to explore the nonlinear optical crystal with broad infrared band, that studies on CsGeX₃ (X=Cl, Br, I) series crystals possessing broad limit transparent harmonious wavelength and tall laser damage threshold are paid more and more attention.Adopting a method of combining both theory and experiment, Our study on the new infrared nonlinear optical crystal CsGeBr₃ is divided into two parts: computer theoretical calculation and single-crystal growth. And study objects are enlarged to CsGeCl₃ CsGeI₃.We use CASTEP-based on the Density Functional Theory of First Principle in Quantum Mechanics, to sep up and optimize cells of CsGeX₃(X=Cl, Br,I)and calculate some properties of them such as band structure , density of phonon states density of electron states, which change regularly with increasing of atomic numbers. We conclude theoretical transmittance of CsGeBr₃, from 0. 52μm to 45μm, which means its bright future in the field of infrared nonlinear optical crystal material.In the part of study on crystal growth, a suit of equipment for single crystal growth in liquor with low temperature is designed and manufactured, and CsGeBr3 is synthesized by an improved method and characterized by powder X-ray diffraction, and infrared spectrum test of TG DTA are also put up. A proper liquor system for single crystal growth is selected by the study of microscopic crystals, which lay the groundwork for the study of solubility curve and single crystal growth.Results show that in infrared wave range, up to 25μm, CsGeBr₃ possesses a high transmittance of 80%, which means a better property of infrared transmittance than that of CsGeCl₃, and there is a big hope of growing its single crystal. So we predict CsGeBr₃ as a potential new crystal in field of infrared...