Single crystals of the hexagonal apatite, Nd9.33(SiO4)6O2, were prepared by using the float-zone method. An anisotropy of its conductivity was investigated. The conductivity parallel to the c-axis was 2.1 x 10-8S/cm at 30C. It was higher by about an order of magnitude, as compared with the perpendicular component.

Oxide Ionic Conductivity of Apatite Type Nd9.33(SiO4)6O2 Single Crystal. S.Nakayama, M.Sakamoto, M.Higuchi, K.Kodaira, M.Sato, S.Kakita, T.Suzuki, K.Itoh: Journal of the European Ceramic Society, 1999, 19[4], 507-10