Observation of the X-ray Diffuse Scattering and the Nonlinear Conduction in (MSe_4)_2I (M=Ta and Nb)(EXPERIMENTS ON (MX_4)_nY COMPOUNDS, International Symposium on NONLINEAR TRANSPORT AND RELATED PHENOMENA IN INORGANIC QUASI ONE DIMENSIONAL CONDUCTORS)

Abstract

X-ray diffraction and conductivity measurements have been made on (MSe_4)_2I,(M=Ta and Mb). A phase transition of (NbSe_4)_2I was found and the transition temperature T_c was determined to be about 210K by the conductivity measurement. For (TaSe_4)_2I, T_c was about 260K as reported previously. Superlattice reflections due to the formation of charge density wave(CDW) in (TaSe_4)_2I were observed at points ^^-__q=(±0.05, +0.05, ±0.085). The type of CDW of (NbSe_4)_2I is known to be identical to that of (TaSe_4)_2I. Temperature dependence of the threshold electric field of nonlinear conductivity is consistent with the result in previous reports.