Ordered structure and thermal expansion in tungsten bronze Pb 2K0.5Li0.5Nb5O15

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Author(s)

  • Kun Lin
  • Yangchun Rong
  • Hui Wu
  • Qingzhen Huang
  • Li You
  • Longlong Fan
  • Jun Chen
  • Xianran Xing

Detail(s)

Original languageEnglish
Pages (from-to)9174-9180
Journal / PublicationInorganic Chemistry
Volume53
Issue number17
Publication statusPublished - 2 Sept 2014
Externally publishedYes

Abstract

The crystal structure and thermal expansion behaviors of a new tetragonal tungsten bronze (TTB) ferroelectric, Pb2K0.5Li 0.5Nb5O15, were systematically investigated by selected-area electron diffraction (SAED), neutron powder diffraction, synchrotron X-ray diffraction (XRD), and high-temperature XRD. SAED and Rietveld refinement reveal that Pb2K0.5Li0.5Nb 5O15 displays a commensurate superstructure of simple orthorhombic TTB structure at room temperature. The structure can be described with space group Bb21m. The transition to a paraelectric phase (P4/mbm) occurs at 500°C. Compared with Pb2KNb5O 15 (PKN), the substitution of 0.5K+ with small 0.5Li + into PKN causes the tilting of NbO6 octahedra away from the c axis with Δθ ≈ 10°and raises the Curie temperature by 40°C, and the negative thermal expansion coefficient along the polar b axis increases more than 50% in the temperature range 25-500°C. We present that, by introduction of Li+, the enhanced spontaneous polarization is responsible for the enhanced negative thermal expansion along the b axis, which may be caused by more Pb2+ in the pentagonal caves. © 2014 American Chemical Society.

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Citation Format(s)

Ordered structure and thermal expansion in tungsten bronze Pb 2K0.5Li0.5Nb5O15. / Lin, Kun; Rong, Yangchun; Wu, Hui et al.
In: Inorganic Chemistry, Vol. 53, No. 17, 02.09.2014, p. 9174-9180.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review