Abstract
YAG was synthesized by a TW method from the mixed heterogeneous solutions consists of the aqueous individual solutions made of yttrium nitrate and aluminum nitrate with the small quantity of each of tetraethyl orthosilicate and 2M-HCl, by adding the small quantity of the aqueous solution made of neodymium nitrate as additive. In this study, keeping the constant proportion of aluminum nitrate with a composition of 5.0×10−2 mole, only part of yttrium nitrate with a composition of 3.0×10−2 mole was substituted by the neodymium nitrate with a composition of 3.0×10−4 mole. YAG began to form from the constant temperature near 920°C and its single phase was obtained at a temperature of 1160°C. On the other hand, YAG single phase did not obtain because the slight amounts of the crystalline phases such as YAM, Y2O3, α-Al2O3 and θ-Al2O3 were deposited separately or simultaneously at temperatures of 1180° to 1280°C, except that the single phase of YAG was obtained at a temperature of 1300°C. It was thought that YAG single phase was obtained as YAG was produced in a reaction of YAP with α-Al2O3 at a temperature of 1160°C and in a reaction of YAM with θ-Al2O3 at a temperature of 1300°C. It was also found that the phase transformation of α-Al2O3 into θ-Al2O3 began to occur from the constant temperature near 1240°C and this phenomenon was completed by causing the disappearance of all α-Al2O3 at a temperature of 1300°C.
