Sintering transient second-phase

Rhodes used oxalic acid co-precipitation method to produce lanthanum doped yttria powder and sintered by controlled transient solid second-phase sintering method. Materials with near theoretical total transmittances and specular transmittance within 6% of theoretical were obtained. 

W.H. Rhodes, Controlled Transient Solid Second-Phase Sintering of Yttria, Journal of the American Ceramic Society, 6A 13-9(1981). 

In the case of the 90% MgO class refractory, the brick contained 95.5% MgO, 2.7% CaO, and 1.4% Si02. This implies that the native silicate in the brick is dicalcium silicate (2CaO Si02)—a very refractory second phase providing for a part of the bonding in a product where direct sintered bonds between adjacent MgO aggregate particles predominate. In service, a transient period... 

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