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Subsolidus Phase Relationships in the AO-AI2O3-Nb2O5(A=Ca, Sr) Systems



Julia Y. Chan, Wilma Feb-Ayala, J. M. Loezos, L D. Rotter, Lyle E. Levine, Richard G. Geyer


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 1350-1525 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 (0
Sigma Xi Web Page


microwave dielectric, oxides, properties phase equilibria, structure


Chan, J. , Feb-Ayala, W. , Loezos, J. , Rotter, L. , Levine, L. and Geyer, R. (2021), Subsolidus Phase Relationships in the AO-AI<sub>2</sub>O<sub>3</sub>-Nb<sub>2</sub>O<sub>5</sub>(A=Ca, Sr) Systems, Sigma Xi Web Page (Accessed April 15, 2024)
Created October 12, 2021