Microstructural and Microwave Dielectric Properties of Bi12GeO20 and Bi2O3-Deficient Bi12GeO20 Ceramics

Xing Hua Ma, Sang Hyo Kweon, Sahn Nahm, Chong-Yun Kang, Seok Jin Yoon, Young Sik Kim, Won Sang Yoon

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

Bi12GeO20 ceramics sintered at 800°C had dense microstructures, with an average grain size of 1.5 μm, a relative permittivity (εr) of 36.97, temperature coefficient of resonance frequency (τf) of -32.803 ppm/°C, and quality factor (Q × f) of 3137 GHz. The Bi12-xGeO20-1.5x ceramics were well sintered at both 800°C and 825°C, with average grain sizes exceeding 100 μm for x ≤ 1.0. However, the grain size decreased for x > 1.0 because of the Bi4Ge3O12 secondary phase that formed at the grain boundaries. Bi12-xGeO20-1.5x (x ≤ 1.0) ceramics showed increased Q × f values of >10 000 GHz, although the εr and τf values were similar to those of Bi12GeO20 ceramics. The increased Q × f value resulted from the increased grain size. In particular, the Bi11.6GeO19.4 ceramic sintered at 825°C for 3 h showed good microwave dielectric properties of εr = 37.81, τf = -33.839 ppm/°C, and Q × f = 14 455 GHz.

Original languageEnglish
JournalJournal of the American Ceramic Society
DOIs
Publication statusAccepted/In press - 2016

Keywords

  • LTCC
  • Dielectric materials/properties
  • Grain growth
  • Grain size
  • Sinter/sintering

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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