Neutron and electron diffraction studies of La(Zn_1/2Ti _1/2)O₃ perovskite

The crystallography and microwave dielectric properties of La(Zn _1/2Ti_1/2)O₃ (LZT) ceramics prepared via the mixed-oxide route were investigated in this study. While samples were largely single phase, small amounts of ZnO impurity were detected in sintered pellets. Observed reflections in electron and neutron diffraction patterns indicate that the symmetry of LZT is P2₁/n. The B site is ordered on {110} or pseudocubic {111}, but the presence of the pseudocubic 1/2(111) reflection is in itself insufficient to indicate the existence of such order. Rietveld refinements of the neutron diffraction data yield an excellent fit for such a model. The structure is highly twinned, with variants related through common {211} composition planes and 90° rotations about 〈Oil〉. The microwave dielectric properties measured were ε_r = 34, Qf = 36 090 and τ_f= - 70 MK^-1.