Band gap narrowing in ferroelectric KNbO3-Bi(Yb,Me)O3 (Me=Fe or Mn) ceramics

PASCUAL-GONZALEZ, Cristina, SCHILEO, Giorgio and FETEIRA, Antonio (2016). Band gap narrowing in ferroelectric KNbO3-Bi(Yb,Me)O3 (Me=Fe or Mn) ceramics. Applied Physics Letters, 109 (13).

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Link to published version:: 10.1063/1.4963699

Abstract

The direct optical band gap in ferroelectric KNbO3-Bi(Yb,Me)O3 (Me=Fe or Mn) ceramics fabricated by the solid state reaction method varies from 3.2 eV for KNbO3 down to 2.2 eV for 0.95KNbO3-0.05BiYbO3, as revealed by optical spectroscopic ellipsometry. This narrowing of band gap is accompanied by an apparent increase of the room-temperature relative permittivity from 320 for KNbO3 to 900 for 0.95KNbO3-0.05BiYbO3. All compositions studied exhibit dielectric anomalies associated with structural phase transitions and their ferroelectric nature is corroborated by the presence of a sharp mixed mode (at ~190 cm-1) and by a Fano-type resonant dip in their Raman spectra.

Item Type: Article
Research Institute, Centre or Group: Materials and Engineering Research Institute > Structural Materials and Integrity Research Centre > Centre for Corrosion Technology
Identification Number: 10.1063/1.4963699
Depositing User: Antonio Feteira
Date Deposited: 16 Sep 2016 14:27
Last Modified: 30 Nov 2016 22:23
URI: http://shura.shu.ac.uk/id/eprint/13536

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