Relationship between Conductivities and Compositions Determined by EPMA for Apatite-type Nd_x(SiO₄)₆O_1.5x−12 Single Crystals

Abstract

Four kinds of single crystals of hexagonal apatite type Nd_x(SiO₄)₆O_1.5x−12 (x = 8–9.33), which is an oxide ionic conductor, were prepared by the FZ method and samples for electrical measurements (the conductivity components parallel and perpendicular to the c-axis of single crystal) were prepared. The conductivities of the component parallel to the c-axis were higher about one order of magnitude, compared with those of the component perpendicular. The values of (Nd/Si) × 6 of four kinds of samples were 8.63, 8.67, 8.91 and 9.33 determined by electron probe micro-analysis. The conductivity was slightly increased with decreasing the value of (Nd/Si) × 6.