The Local Structure and Metal-Insulator Transition in a Ba3Nb5−xTixO15 System

G. M. Pugliese, F. G. Capone, L. Tortora, F. Stramaglia, L. Simonelli, C. Marini, Y. Kondoh, T. Kajita, T. Katsufuji, T. Mizokawa, N. L. Saini*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The local structure of the filled tetragonal tungsten bronze (TTB) niobate Ba3Nb5−xTixO15 (x = 0, 0.1, 0.7, 1.0), showing a metal-insulator transition with Ti substitution, has been studied by Nb K-edge extended X-ray absorption fine structure (EXAFS) measurements as a function of temperature. The Ti substitution has been found to have a substantial effect on the local structure, that remains largely temperature independent in the studied temperature range of 80–400 K. The Nb-O bonds distribution shows an increased octahedral distortion induced by Ti substitution, while Nb-Ba distances are marginally affected. The Nb-O bonds are stiffer in the Ti substituted samples, which is revealed by the temperature dependent mean square relative displacements (MSRDs). Furthermore, there is an overall increase in the configurational disorder while the system with Nb 4d electrons turns insulating. The results underline a clear relationship between the local structure and the electronic transport properties suggesting that the metal-insulator transition and possible thermoelectric properties of TTB structured niobates can be tuned by disorder.

Original languageEnglish
Article number4402
JournalMaterials
Volume15
Issue number13
DOIs
Publication statusPublished - 2022 Jul 1

Keywords

  • local structure
  • metal-insulator transition
  • TTB niobates
  • X-ray absorption spectroscopy

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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