Ba2Ti9O20 materials were prepared by reacting nano-sized BaTiO3 powders (50 nm) with TiO2 powders (∼100 nm). The materials prepared by calcination and sintering 2-step processes possess high sintered density (> 96.5% T.D.) and exhibit marvelous microwave dielectric properties (K = 39.5, Q × F = 33,000), which are markedly superior to the materials prepared via the reaction of BaCO3 and TiO2 powders. Direct reactive-sintering of nano-BaTiO3 and TiO2 mixture directly leads to even better microwave dielectric properties, which is ascribed to the more completeness in converting the BaTiO3 particulates into Ba2Ti9O20 Hollandite-like phase.
