Synthesis of Nd:YAG Nanopowder for transparent ceramics

Abstract

Current trend on high energy laser is now the booming field of research, because of the continuous increase in the power output such as 100 KW. The increase in power output is due to increase in active ion concentration and size of the laser host material. The current work is based on the synthesis of Yttrium Aluminium Garnet (YAG-Y3Al5O12) nanopowders for the fabrication of transparent ceramic laser gain media. YAG nanopowders have been prepared by co-precipitation route by using Aluminum nitrate and Yttria as starting precursor and precipitated against ammonium bicarbonate at low temperature (10 o C) and pH 7.3. All the subsequent washing and freeze drying processes to obtain agglomerate free powder are carried out at 10 o C and -52 oC, respectively. The as-precipitate agglomerate free powder is further calcined in the temperature range from 900 to 1100 o C. The powder calcined at 900 o C is highly reactive with a particle size below 50 nm and surface area of 42 m2/gm. The calcined powders are doped with silica, consolidated through uniaxial pressing and followed by atmospheric pressure-less sintering at 1650 o C for 6 hr. Sintering profile has been optimized on the basis of achieved ĉrel ~ 99% and further proceed for spark plasma sintering with addition of 5at% Nd dopant concentration. The spark plasma sintering process is carried out at 1300 and 1400 o C for 5 minutes with a uniaxial loading of 62 MPa. Optical transparency of spark plasma sintered disc specimen is rendered transmission of 30 % in the infrared range and 10 % in the visible range.