Microwave Dielectric Properties of (1 − x )( Mg _0.95 Ni _0.05 ) TiO ₃ – x ( Ca _0.8 Sr _0.2 ) TiO ₃ Ceramic System With Near‐Zero Temperature Coefficient

The microwave dielectric properties of the (1 − x )( Mg _0.95 Ni _0.05 ) TiO ₃ – x ( Ca _0.8 Sr _0.2 ) TiO ₃ ceramic system prepared by mixed oxide route have been investigated. The crystal structures and the microstructures of the ceramics were characterized by means X ‐ray and scanning electron microscopy. The microwave dielectric properties are strongly related to the density and matrix of the specimen. Combination of ( Mg _0.95 Ni _0.05 ) TiO ₃ (ilmenite‐type structure) and ( Ca _0.8 Sr _0.2 ) TiO ₃ (perovskite‐structured) forms a two‐phase system and leads to a near‐zero temperature coefficient (τ _f ). With increasing x , the quality factor ( Q × f ) decreased and dielectric constant (ε _r ) increased. A new microwave dielectric material 0.95( Mg _0.95 Ni _0.05 ) TiO ₃ –0.05( Ca _0.8 Sr _0.2 ) TiO ₃ , possessing excellent microwave dielectric properties with a dielectric constant (ε _r ) of 21.68, a quality factor ( Q × f ) of 94,000 (GHz) and a temperature coefficient (τ _f ) of approximately −5.2 ppm/°C at 1275°C for 4 h, is proposed as a suitable candidate material for microwave applications requiring low dielectric loss.