Röntgenographische, thermoelektrische, und IR-spektroskopische Untersuchung des Spinellsystems Li xMn 1- xV 2O 4

The spinels of the system Li _xMn _{1- x}V ₂O ₄ (0 ⩽ x ⩽ 1) have been prepared at 700-750°C from LiV ₂O ₄ and MnV ₂O ₄. The lattice constants decrease linearly with increasing x. In the region x>0.75, the d-electrons of V should be delocalized as the VV distances are lower than the critical VV separation of 2.94 Å. Experimentally, the samples with x>0.6 show no IR absorption bands and the Seebeck coefficient is near zero. The Seebeck coefficient can be described with a model of intermediate polarons and can be expressed by the equation Θ = 198 log [1 + {(1 - x) ⁵}/{x}] .