A novel phase-controlling-sintering route for improvement of diopside-based microwave dielectric materials

Abstract The present work suggests a new reactive route for obtaining MgTiO 3 -doped CaMgSi 2 O 6 glass–ceramic microwave dielectric material with very low dielectric constant ( e r ), high quality factors ( Q × f ) and nearly zero temperature coefficient of resonant frequency ( τ f ). Sintering of the mixture of CaMgSi 2 O 6 glass and synthesized MgTiO 3 powders at 950 °C results in glass-ceramics containing Mg 2 SiO 4 and CaTiO 3 phases. Such glass-ceramics possess increased quality factors and improved temperature coefficient of resonant frequency, because the Mg 2 SiO 4 and CaTiO 3 phases own ultra-high Q × f and positive τ f , respectively. Microstructure features and EPMA line scan show the concentration gradients of Ca, and Si atoms altering from matrix region toward MgTiO 3 particle. These data indicate that during the liquid phase sintering silica glass reacts with MgTiO 3 ceramic particles forming the Mg 2 SiO 4 and CaTiO 3 phases.