Preparation and characterization of composition graded K(Ta,Nb)O3 crystals

M. Shimada, H. Yamane

Research output: Contribution to journalConference articlepeer-review

Abstract

K(Ta,Nb)O3 single crystals having a composition gradient were prepared by non-equilibrium cooling from melts of K(TaxNb1-x)O3 with x=0.3-0.4. Electron microprobe analysis revealed that the Ta content was rich in the core region of the crystals and decreased gradually to the edge with increasing Nb content. Zoning Structures were observed in the crystals by polarized optical microscopy and high-temperature microscopy. There were three zones (cubic, tetragonal and orthorhombic phases from the core to the rim) or two zones (tetragonal (core) and orthorhombic phases (rim)). The boundary between the cubic and tetragonal zones moved to the edge with increasing temperature. The crystals exhibited broad peaks for the dielectric constant against temperature. No frequency dependence of the peak position was recognized from 100 kHz to 10 MHz.

Original languageEnglish
Pages (from-to)1231-1234
Number of pages4
JournalKey Engineering Materials
Volume206-213
Issue numberII
Publication statusPublished - 2001 Jan 1
Event7th Conference and Exhibition of the European Ceramic Society - Brugge, Belgium
Duration: 2001 Sep 92001 Sep 13

Keywords

  • Dielectric constant
  • Functionally graded oxides
  • Non-equilibrium cooling
  • Perovskite-type structure
  • Phase transformation

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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