Role of the Nb impurities on the thermal conductivity of (Ta1-xNbxSe4)(2)Ialloys in the vicinity of the Peierls transition

We report measurements of the thermal conductivity (kappa) of pure (TaSe4)( 2)I and niobium doped (Ta0.99Nb0.01Se4)(2)I, in the temperature range 100-3 40 K. Results show that the Peierls transition in pure (TaSe4)(2)I is smear ed in doped (Ta0.99Nb0.01Se4)(2)I sample. The self-consistent analysis of a ll contributions to the thermal conductivity of pure (TaSe4)(2)I provide ev idence for the collective mode aspects of the heat conduction. There exists significant additional contribution to the thermal conductivity originatin g from the thermally assisted phason motion and charge density wave fluctua tions. By introducing niobium impurities into (TaSe4)(2)I the charge densit y waves are less developed and the additional contributions to the thermal conductivity are significantly reduced. (C) 1999 Elsevier Science B.V. All rights reserved.