The crystal structure of yttrium tantalate mineral from Suishoyama, Fukushima Prefecture, Japan

Abstract

The chemical composition and crystal structure of yttrium tantalite mineral from Suishoyama, Fukushima Prefecture, Japan, were determined. The electron microprobe analysis gave the following empirical formula; (Y_0.78Yb_0.06Dy_0.04Er_0.04Gd_0.02Lu_0.01Ho_0.01Sm_0.01Ca_0.01Tm_0.01Tb_0.01U_0.01)_~1.01(Ta_0.58Nb_0.39Ti_0.02)_~0.99O₄. The mineral is monoclinic, with space group P2/a and lattice parameters of a = 5.292(2), b = 5.452(2), c = 5.1149(18) A, beta = 95.89(3)deg, Z = 2. The structure analysis converged to R1 = 0.0340. This mineral is not isostructural with formanite-(Y), fergusonite-(Y), and fergusonite-beta-(Y). This mineral is natural analogue of the synthetic YTaO₄-M'.