Structural phase transitions and superconductivity in hexagonal tungsten bronzes

Ranninger, J. ; Sinha, K. P. (1985) Structural phase transitions and superconductivity in hexagonal tungsten bronzes Proceedings of the Indian Academy of Sciences - Chemical Sciences, 95 (1-2). pp. 93-102. ISSN 0253-4134

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Official URL: http://www.ias.ac.in/j_archive/chemsci/95/1/93-102...

Related URL: http://dx.doi.org/10.1007/BF02839720

Abstract

The anomalous behaviour of the superconducting transition temperature Tc as a function of x in MxWO3 (hexagonal tungsten bronzes), where M = K, Rb or Cs and 0·16 < x < 0.33, is explained in terms of structural transitions involving WO6 octahedral chains which are subject to Jahn-Teller (J-T) effect. Above a critical concentration (xc ~ 0.24) there is cooperative J-T effect resulting in a structural transition. Below this, there will exist only local distortions. The effect of these is to modify the density of states and lead to shifting and splitting of the relevant peaks. It is shown that the density of states profile at the Fermi level controls the superconducting transition temperatures as a function of x. The conduction electrons in these systems are J-T polarons subject to competition between symmetry-breaking distortion and the band delocalizing effects.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:Hexagonal Tungsten Bronzes; Jahn-Teller Polarons; Superconductivity; Structural Transition
ID Code:48138
Deposited On:14 Jul 2011 10:23
Last Modified:18 May 2016 03:27

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