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Structure and Microwave Dielectric Properties of Hexagonal Ba[Ti 1− x (Ni 1/2 W 1/2 ) x ]O 3 Ceramics
Author(s) -
Zhao Fei,
Yue Zhenxing,
Pei Jing,
Zhuang Hao,
Gui Zhilun,
Li Longtu
Publication year - 2007
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2007.01801.x
Subject(s) - octahedron , rietveld refinement , materials science , crystallography , dielectric , x ray crystallography , analytical chemistry (journal) , powder diffraction , ion , crystal structure , diffraction , phase transition , phase (matter) , hexagonal crystal system , space group , solid solution , mineralogy , chemistry , condensed matter physics , physics , metallurgy , optics , optoelectronics , organic chemistry , chromatography
Microwave dielectric ceramics with the composition of Ba[Ti 1− x (Ni 1/2 W 1/2 ) x ]O 3 ( x =0.4–0.6) were prepared by a solid‐state reaction method. The evolution of the crystalline phases was investigated by X‐ray powder diffraction analysis. A cubic‐to‐hexagonal phase transition occurred between 1000° and 1300°C. The phase transition is irreversible; thus, the hexagonal phase remains stable at room temperature. The X‐ray powder diffraction data for x =0.5 were refined using the Rietveld method. It was identified as a h ‐BaTiO 3 ‐type hexagonal perovksite with the space group of P 6 3 / mmc . It also reveals that random occupancy of Ti 4+ and W 6+ ions occurs in the B‐site substructures, whereas Ni 2+ ions exclusively occupy the octahedral site in the corner‐sharing octahedron. The dielectric properties of dense‐sintered ceramics were characterized at microwave frequencies. With an increase in x from 0.4 to 0.6, the Q × f value increased from 26 700 to 42 000 GHz, whereas ɛ r decreased from 29.8 to 20.0, and τ f from +6.5 to −9.9 ppm/°C.