Research On Preparation Of Laser Ceramics Powders

Being a typical ceramics material, yttrium aluminum garnet (YAG) has excellent mechanical, thermal and optical properties, which is a promising material used as phosphors and laser media. Recently, more attention has been paid to low-temperature synthesis of YAG powders and fabrication of transparent YAG. It was showed through the research that transparent polycrystalline YAG ceramics are low cost, and can be highly doped with Nd³⁺ and possible for lager size laser polycrystal. It is a promising ceramic for high power laser host materials. In 1995, Ikesue had prepared transparent Nd³⁺:YAG by solid state reaction method and its refractive index and thermal conductivity were nearly equivalent to those of a YAG single crystal. The emergence of this Nd³⁺:YAG laser transparent ceramics presented enormous potential for communication and military applications give impetus to the study of laser transparent ceramics materials.In this work, Nd³⁺: YAG powder was obtained through chemical co-precipitation method and sol-gel method to study the effects of preparation methods, precursor powders are synthesized by two different wet-chemical process, i.e. citric acid process, and co-precipitation process using ammonium hydrogen carbonate as the precipitant. YAG powders sinter ability; pore size distribution grain growth and micro-structural evolution are investigated by sintering and the constant heating rate sintering. And the Nd³⁺:YAG precursor were characterized by TG-DTA,XRD and SEM. At last, CNd:1at.% and 5at.%Nd³⁺:YAG was prepared. Factors test method was used during the whole experiment to analyses the influence that quantity of doping Nd³⁺, precipitator and temperature of sintering work on transparency of polycrystalline Nd³⁺: YAG ceramics. Finally factors influencing on optical transmittance of polycrystalline Nd³⁺:YAG ceramics and optimization formulation for producing polycrystalline Nd³⁺:YAG ceramics were found out according to the results.Based on accurate knowledge of the processing of ultra fine YAG powder and improved understanding of the microstructal evolution and sintering mechanism, the influence of chemical composition of YAG powders, press techniques and the sintering schedules on ceramics transmission is evaluated.