ジルコニア-エルビア正方晶固溶体の合成と焼結

抄録

The preparation of zirconia/erbia tetragonal solid solution was attempted by sintering of powders produced by coprecipitation. Calcined powders were attrition milled and green bodies densified to materials having grain size of a nanometer scale. Fired materials reached high density after firing at any temperatures above 1350°C for times of 1h or more; they had a tetragonal structure, provided that the erbia content exceeded 1.5mol%. Materials containing 1.5mol% erbia consisted of both monoclinic and tetragonal phases, when the firing conditions were selected at the lowest temperature for densification (1h at 1350°C). In all other cases, only the monoclinic structure could be detected. Materials containing 2, 2.5 and 3mol% erbia had tetragonal symmetry. In particular, tetragonal solid solutions contaning 2mol% Er₂O₃ mantained such structure until their grain size did not exceed 1μm, at larger grain sizes they transformed to monoclinic. The tetragonal lattice parameters were measured by X-ray diffraction analysis in all the tetragonal materials and they agreed with those previously reported by other authors. The crystallographic a/c ratio had influence on the grain tranformability: the lower the ratio, the lower the tetragonal/monoclinic transformation ratio.