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Dielectric and Microstructural Study of the SrWO 4 , BaWO 4 , and CaWO 4 Scheelite Ceramics
Author(s) -
Maček Kržmanc Marjeta,
Logar Manca,
Budič Bojan,
Suvorov Danilo
Publication year - 2011
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.1551-2916.2010.04378.x
Subject(s) - scheelite , materials science , ceramic , mineralogy , electroceramics , metallurgy , dielectric , geology , optoelectronics , tungsten , fabrication , medicine , microfabrication , alternative medicine , pathology
MWO 4 (M=Ca, Sr and Ba) scheelite ceramics were studied in terms of their syntheses, sintering, solubility in water, and dielectric response after storing them in dry and moist atmospheres. Of the studied scheelites, the CaWO 4 possessed the most promising dielectric properties (ɛ=10.9, Q × f =105 600 GHz), which were stable under the influence of humidity. BaWO 4 and SrWO 4 exhibited ɛ=9.0 and Q × f values of 32 200 and 62 600 GHz, respectively. The most detrimental effect of the moisture was observed for SrWO 4 . A sodium impurity present in the SrCO 3 reagent (0.35 wt%), which was used for the synthesis of the SrWO 4 , was found to lower the sintering temperature, enhance the grain growth, and change the other properties of the ceramics, such as humidity susceptibility and solubility in water. The evident tendency of the ceramics to attract water and the increased dissolution of tungstate were observed for all MWO 4 scheelite ceramics, which were sintered with the help of Na 2 CO 3 or Li 2 CO 3 (0.5 wt%) sintering aids. The results of the present study suggest that the physical and chemical properties of the ceramics should be carefully considered in the case of using of alkaline‐containing sintering aids.