Solid-state-reactive fabrication of Cr, Nd:YAG transparent ceramics:: the influence of raw material

Solid-state reactive sintering a stoichiometric mixture of commercial gamma-Al2O3, Y2O3, Nd2O3 and Cr2O3 powders was conducted at 1800 degrees C with tetraethoxysilane (TEOS) as sintering aid and CaO as charge compensator. The cubic garnet structure of YAG (Y3Al5O12) as well as orthorhombic structure of YAP (YAlO3) formed in the sample due to mass loss of gamma-Al2O3 during sintering. The sample obtained was fully dense but not transparent and the width of grain boundary phase was about 300 nm contained a significant amount of Si and Nd, compared with the inner grains. The doping concentration of Nd and Si in YAlO3 phase is much larger than that in Y3Al5O12 phase. However, when a little more gamma-Al2O3 than stoichiometric composite was added, transparent Cr,Nd:YAG ceramic could be obtained. The optical transmittance of the sample sintered at 1800 degrees C for 10h is 68.5% at 1064nm and the average grain size is about 10,mu m. (C) 2008 The Ceramic society of Japan. All rights reserved.