Microwave synthesis and sintering of Mg_4Nb_2O_9 nanoceramics

摘要

Mg_4Nb_2O_9 nanopowders were prepared from MgO and Nb_2O_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_4Nb_2O_9 nanopowders with an average grain size of 127 nm were obtained at 850, 130 ℃ lower than that required by a conventional solid state reaction process. Mg_4Nb_2O_9 ceramics sintered at a low temperature of 1,300 ℃ using microwave heating showed almost full density and excellent microwave dielectric properties (ε_r = 12.9, Q×f= 174,200 GHz and τ_f = -68).