Effects of structural characteristics on microwave dielectric properties of (1-x)CaWO4 -xLaNbO4 ceramics

• Published in: Journal of electroceramics Vol. 17; no. 2-4; pp. 471 - 477
• Main Authors: Kim, Eung Soo, Kim, Soon Ho
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Heidelberg Springer 01-12-2006; Springer Nature B.V
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Dielectric properties; Electrotechnical and electronic ceramics; Exact sciences and technology; Grain size; Studies; Technical ceramics; Lanthanum Orthoniobates; Scanning electron microscopy; Calcium Tungstates; Electric polarizability; Electrical properties; Dielectric properties; Binary system; CaWO4-LaNbO4; Microwave; Composition effect; Niobates; Microwave dielectric properties, Oxygen bond valence, Atomic packing fraction, Dielectric polarizability; Experimental study; Solid solution; X ray diffraction; Oxide ceramics; Structure composition relationship; Valence; Property structure relationship; Electroceramics
• ISSN: 1385-3449; 1573-8663
• DOI: 10.1007/s10832-006-8571-7

Issue Title: Special Issue: ICE-2005 International Conference on Electroceramics Dependences of microwave dielectric properties on the structural characteristics of (1-x)CaWO^sub 4^-xLaNbO^sub 4^ ceramics were investigated as a function of LaNbO^sub 4^ content (0.0 ≤ x ≤ 0.5). A single phase with tetragonal scheelite structure was obtained up to x = 0.35, and then the mixture phases with scheelite and fergusonite structure were detected. With the increase of LaNbO^sub 4^, the deviation of the observed dielectric polarizabilities calculated by the Clausius-Mosotti equation from the theoretical values calculated by the additivity rule of dielectric polarizability, was decreased due to the decrease of oxygen bond valence in ABO^sub 4^ scheelite structure. Dielectric constant (K) and temperature coefficient of resonant frequency (TCF) were increased with LaNbO^sub 4^ content due to the decrease of oxygen bond valence. Q fvalue was dependent on the atomic packing fraction of unit cell as well as the grain size. Typically, K = 13.3, Qf = 50,000 GHz and TCF = -8.7 ppm/^sup o^C were obtained for the specimens with 0.3 mol of LaNbO^sub 4^ sintered at 1150^sup o^C for 3 h.[PUBLICATION ABSTRACT]