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Crystal structure and microwave dielectric properties of La 2 (Zr 1− x Ti x ) 3 (MoO 4 ) 9 (0 ≤ x ≤ 0.1) ceramics
Author(s) -
Zhang Yunhui,
Wu Haitao
Publication year - 2019
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/jace.16268
Subject(s) - lattice energy , polarizability , dielectric , thermal expansion , materials science , ceramic , bond energy , analytical chemistry (journal) , chemical bond , crystal structure , bond length , microwave , crystallography , mineralogy , chemistry , molecule , metallurgy , physics , optoelectronics , organic chemistry , chromatography , quantum mechanics
La 2 (Zr 1− x Ti x ) 3 (MoO 4 ) 9 (0 ≤ x ≤ 0.1) ceramics were prepared by the traditional solid‐state reaction method. XRD analysis showed that La 2 (Zr 1− x Ti x ) 3 (MoO 4 ) 9 (0 ≤ x ≤ 0.1) ceramics belonged to a trigonal system. Based on the chemical bond theory, the consequences of bond energy, bond ionicity, lattice energy, and thermal expansion coefficient of ceramics on microwave dielectric properties were discussed. As Ti 4+ addition was increased, the reduction in dielectric constant was ascribed to the fact that the polarizability of Ti 4+ is smaller than Zr 4+ , and the downward trend was related to the bond ionicity. Besides, the tendency of Q·f value depended on the packing fraction and the lattice energy. The improvement in τ f value, the increase in bond energy, and the decrease in the coefficient of thermal expansion were all correlated. The far‐infrared spectra implied that the absorptions of structural phonon oscillation were the main reason for the maximum polarization contribution. La 2 (Zr 0.92 Ti 0.08 ) 3 (MoO 4 ) 9 ceramics sintered at 750°C for 4 hours exhibited the best dielectric properties ( ε r = 10.33, Q·f = 80 658 GHz, and τ f = 3.48 ppm/°C).