Departmental Papers (MSE)

Document Type

Journal Article

Date of this Version

July 2006

Comments

Copyright The American Ceramic Society. Reprinted from Journal of the American Ceramic Society, Volume 89, Issue 7, July 2006, pages 2264-2270.

Abstract

The effect of different muffling environments on the structure and dielectric losses of Ba(Zn1/3Nb2/3)O3 (BZN) microwave ceramics was investigated. The microwave dielectric losses of stoichiometric BZN pellets heated in ZnO-rich environments were severely degraded (e.g. Q×f~15 000 in ZnO powder) compared with samples muffled in their own powder (Q×f~80 000). Structure analyses and gravimetric measurements confirmed that the ceramics muffled in ZnO powder or vapor absorb excess ZnO to form non-stoichiometric solid solutions with reduced cation order and Q. By using starting compositions in the (1−x)BZN−(x)BaNb4/5O3 binary (x=0.04), the stoichiometry can be tailored to ensure that after the uptake of ZnO, the ceramics remain well ordered and are located in a high Q region of the system. For example, ZnO-vapor-protected (0.96)BZN−(0.04)BaNb4/5O3 reached a very high Q×f(~1 05 000) after sintering at 1400°C for 5 h.

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Date Posted: 05 December 2006

This document has been peer reviewed.