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Microwave Dielectric Properties of A 6 B 5 O 18 ‐Type Perovskites
Author(s) -
Santha Narayana Iyer,
Sebastian Mailadil Thomas
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.1551-2916.2006.01456.x
Subject(s) - dielectric , materials science , analytical chemistry (journal) , scanning electron microscope , microwave , diffraction , x ray crystallography , temperature coefficient , mineralogy , chemical composition , crystallography , chemistry , optics , physics , optoelectronics , chromatography , quantum mechanics , composite material , organic chemistry
Cation‐deficient perovskites with the general formula A 6 B 5 O 18 (A=Ba, Sr, La; B=Nb, Ta, Ti, Zr, Mg, and Zn) have been synthesized and their microwave dielectric properties have been investigated. X‐ray diffraction studies indicate the formation of monophase materials. The structures of Ba 6 Ta 4 TiO 18 and Ba 5 SrTa 4 TiO 18 are different from that of Sr 6 Ta 4 TiO 18 . The A 6 B 5 O 18 have Q × f in the range 5600–51 000 GHz, dielectric constants 26–48, and the temperature coefficient of resonant frequency varies from −39 to +83 ppm/°C, depending on the composition. Scanning electron microscopy studies show that the grain size decreases with an increase in the Sr content.