Preparation of ultra‐low temperature sintering ceramics with ultralow dielectric loss in Na ₂ O– <scp>WO</scp> ₃ binary system

Abstract

Abstract A series of new microwave dielectric ceramics with ultralow dielectric loss in Na 2 O–WO 3 binary system were prepared by the modified solid‐state reaction method at ultra‐low sintering temperatures. Three stable phases, namely Na 2 WO 4 , Na 2 W 2 O 7 and Na 2 W 4 O 13 , were formed in the system. Their stability in the air, phase composition, compatibility with metal electrodes, microstructures, and microwave dielectric properties were investigated. In this binary system, the cubic structure Na 2 WO 4 ceramic sintered at 565°C exhibited the best microwave dielectric properties with a permittivity of 5.6, a Q × f value of 124 200 GHz and a temperature coefficient of −63 ppm/°C at a frequency of 13.1 GHz. The Na 2 WO 4 ceramic is chemically compatible with Ag and Al electrodes. Besides, the Na 2 WO 4 ceramic has favorable stability in the air. Due to the excellent dielectric properties and favorable stability in the air, the Na 2 WO 4 ceramic is a great candidate for LTCC devices.