Solution Combustion Synthesis Of Yag Powder

The research in the field of laser ceramics, as a new component has arrested considerable attention in the recent years, because it is quite significant to improve the properties of the laser by using the ceramics instead of single crystals as the operation material of the solid laser. At the present time,YAG is the most widely-used laser material. It is important to synthesize yttrium aluminum garnet (Y₃Al₅O₁₂,YAG) ceramics with high transparency. In order to produce laser ceramics with high performance, it is vital to synthesize the powders with good dispersity and small particle size, while without hard-agglomeration.This paper attempts to investigate how to synthesize YAG powders by liquid-phase combustion synthesis. During the process of synthesizing YAG powders, yttrium nitrate and alumminium nitrate were selected as raw materials, and citric acid and urea as fuel, and de-ionized water and absolute ethyl alcohol as solvent. Colloidal was formed by water bath heating the primary solution, and the precursors were prepared by the combustion reaction of the colloidal precursors. In the end, the single-phase YAG powders were synthesized by calcinating the precursors at the high temperature. The process for synthesizing single-phase YAG powders by liquid-phase combustion was determined. The phase analysis of the end product has shown that the fuel and solvent affected not only purity but also dispersibility of the YAG powders. Meanwhile, the effects of calcination temperature for preparing the single-phase YAG powders were discussed.The research indicated that intimate contact between the (Y³⁺, Al³⁺) and O^2- was achieved by the process of combustion reaction followed by the process of calcination, which greatly reduced the activation energy of the synthesis reaction, thus YAG powders were obtained at lower temperature.The analysis of thermogravimetry and differential thermal (DTA/TG) curve of the precursors showed that precursors derived with urea as fuel could be changed from amorphous to cystalline YAG phase. The intermediate phase was completely converted to YAG at the temperature of 900°C. On the other hand, the precursors derived with citric acid as fuel could be converted to crystalline nano-size YAG powders at 800°C.X-ray diffraction analysis of the calcinated products indicated that, by using citric acid asfuel and de-ionized water as solvent, the synthesized YAG powders were composed of high degree of crystallinity YAG particles and few intermediate phases.SEM observations of YAG powders have demonstrated that the particle size of the YAG powders was about 100nm, by using citric acid as fuel and de-ionized water as solvent. But the particle size of YAG powders was over 150nm along with intermediate phase if the calcination was conducted, by selecting citric acid as fuel and absolute ethyl alcohol as solvent. In the case of selecting urea as fuel, both de-ionized water and absolute ethyl alcohol do not lead to intermediate phase. YAG powders with no hard-agglomeration and homogeneous grain were synthesized at the calcination temperature of 900°C.