Microwave synthesis and sintering of Mg^sub 4^Nb^sub 2^O^sub 9^ nanoceramics

Issue Title: Special Issue: Failure Analysis in Electronic Devices and Materials Mg^sub 4^Nb^sub 2^O^sub 9^ nanopowders were prepared from MgO and Nb^sub 2^O^sub 5^ mixtures by using a high energy ball milling method, combined with subsequent annealing at low temperatures by microwave heating. After milling for 20 h, pure phase Mg^sub 4^Nb^sub 2^O^sub 9^ nanopowders with an average grain size of 127 nm were obtained at 850, 130 °C lower than that required by a conventional solid state reaction process. Mg^sub 4^Nb^sub 2^O^sub 9^ ceramics sintered at a low temperature of 1,300 °C using microwave heating showed almost full density and excellent microwave dielectric properties ([straight epsilon]^sub r^ = 12.9, Q × f = 174,200 GHz and τ^sub f^ = -68).[PUBLICATION ABSTRACT]