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Crystals of Li2TiGeO5 were obtained by solution-melt crystallization, and those of Na2TiGeO5 were grown from a melt by pulling. The crystals are isostructural with the natisite mineral Na2TiSiO5. The crystal structure of Li2{TiOGeO4} was refined by X-ray diffraction analysis (a four-circle diffractometer, 2θ/θ scan mode, MoK α radiation, θmax = 50°). The unit cell parameters are a = 6.614(4) A and c = 4.435(4) A; space group P4/nmm, Z = 2, ρcalcd = 3.67 g/cm3, R = 0.031, s = 1.128, wR(F 2) = 0.071 (548 reflections with I ≥ 2σI). The ionic conduction in both crystals was found to be anisotropic in the temperature range 250–600°C;. At 400°C;, the conductivity values are 10–4 to 10–5 S/cm along the a axis and 10–6 to 10–8 (for Na2TiGeO5) and 10–7 to 10–9 S/cm (for Li2TiGeO5) along the c axis. |
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