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Solidus Phase Relationships in the AO-Al2O3-Nb2O5 (A = Ca, Sr) Systems

Published

Author(s)

Julia Y. Chan, Wilma Feb-Ayala, L D. Rotter, Igor Levin, Richard G. Geyer

Abstract

Dielectric ceramics for wireless communications exhibiting modest permittivity, high quality factor (Q), and near-zero temperature coefficient are needed for high frequency, high power applications. Efforts are in progress to replace Ta2O5-based ceramics with less costly oxides that exhibit similar properties. Phase equilibria relations in the CaO-Al2O3-Nb2O5 and SrO-Al2O3-Nb2O5 systems have been determined at 1350 degrees C to 1525 degrees C in air. Phase assemblages were determined by x-ray powder diffraction methods at room temperature. The existence of the double perovskites, A2AlNbO6 (A = Ca, Sr), were confirmed in both ternary systems. In the SrO-Al2O3-Nb2O5 system, a previously unreported ternary phase was found to occur between Sr2AlNbO6 and SrO. A series of cryolite-type solid solutions, Sr3(Sr1-xNb2-x)O9-3/2x (O < x < 0.5), will also be described. The results of dielectric property measurements in the two systems will be presented.
Citation
Solidus Phase Relationships in the AO-Al<sub>2</sub>O<sub>3</sub>-Nb<sub>2</sub>O<sub>5</sub> (A = Ca, Sr) Systems

Keywords

microwave dielectric, oxides, properties phase equlibria, structure

Citation

Chan, J. , Feb-Ayala, W. , Rotter, L. , Levin, I. and Geyer, R. (2021), Solidus Phase Relationships in the AO-Al<sub>2</sub>O<sub>3</sub>-Nb<sub>2</sub>O<sub>5</sub> (A = Ca, Sr) Systems, Solidus Phase Relationships in the AO-Al<sub>2</sub>O<sub>3</sub>-Nb<sub>2</sub>O<sub>5</sub> (A = Ca, Sr) Systems (Accessed April 18, 2024)
Created October 12, 2021