Low-temperature synthesis of Mg4Nb2O9 nanopowders by high-energy ball-milling method

The effects of high-energy ball milling and subsequent calcinations on the mixture of MgO and Nb2O5 were investigated. It was found that the formation temperature of the single-phase Mg4Nb2O9 powders had a consanguineous connection with milling time, calcinations temperature and dwell time. With increasing milling time, calcinations temperature and dwell time, the qualitative concentration of Mg4Nb2O9 phase increased. Pure Mg4Nb2O9 nanopowders with average particle size of 72.5 nm were primary synthesized at 900 °C for 3 h from 60 h powders. The Mg4Nb2O9 ceramics with almost full density and an excellent microwave dielectric properties (ɛr = 12.6, Q × f = 175,810 GHz) were obtained after annealing at 1200 °C from the milled 60 h powders.