Thermal conductivity minimum of Nb4Te17I4

Thermal conductivity (kappa) is measured on the quasi-one-dimensional polyt elluride Nb4Te17I4 in the chain direction in the temperature range 4-340 K. At low temperatures (T < 20 K) thermal conductivity of Nb4Te17I4 shows a m aximum like in dielectric crystals. The estimated Debye temperature from lo w temperature thermal conductivity is Theta(D) approximate to 105 K. At tem peratures above the Debye temperature, thermal conductivity slowly decrease s upon increasing the temperature, and shows a minimum around 180 K. Appear ance of the minimum in thermal conductivity is expected, because an estimat ed phonon mean free path at these temperatures is of the order of the latti ce parameter. A very low room temperature value of thermal conductivity kap pa approximate to 2.5 W m(-1) K-1 may reflect disorder of the lattice (C) 1 999 Elsevier Science B.V. All rights reserved.