Microwave dielectric characteristics of 0.75(Al1/2Ta1/2)O-2-0.25(Ti1-xSnx)O-2 ceramics

Abstract

The microwave dielectric characteristics of 0.75(Al1/2Ta1/2)O-2-0.25(Ti1-xSnx)O-2 ceramics were investigated. The microwave dielectric properties of 0.75(Al1/2Ta1/2)O-2-0.25TiO(2) sintered at 1450 degreesC exhibited a dielectric constant (epsilon(r)) of 31.2, a Q.f(0) of 54,590 GHz, and the temperature coefficient of resonant frequency (tau(f)) of +12.8 ppm/degreesC. To control of the tau(f) and enhance the Q.f(0) for 0.75(Al1/2Ta1/2)O-2-0.25TiO(2), Sn4+ was substituted for Ti4+. With an increase of Sri content from 5 to 50 mol%, the epsilon(r) slightly decreased, the Q.f(0) increased and the tau(f) shifted from positive to negative value. The tau(f) within +/-10 ppm/degreesC of zero was realized for the Sri content below 30 mol% and the microwave dielectric properties had the epsilon(r) value of 31.2-26.3, the Q.f(0) of 54,600-70,700 GHz, and tau(f) of +12.8--9.3 ppm/degreesC for this compositions. The relationship between microstructure and microwave dielectric characteristics was investigated. (C) 2003 Elsevier Ltd. All rights reserved.