Investigation of Ag(Ta,Nb)O3 as tunable microwave dielectric

Ag(Ta,Nb)O3 (ATN) has been investigated as a candidate material for an application in tunable high frequency devices. AgTa0.1Nb0.9O3 as a bulk ceramic shows moderate permittivity of ε=310 and visible tunability τ=ε0−εEmaxε0 of 16% for an applied field of 10 kV/cm at room temperature. AgTaxNb1−xO3 powders with 0⩽x⩽0.4 have been prepared by mixed oxide technique. Permittivity, losses and tunability of ATN bulk ceramic and screen printed thick films have been characterized at frequencies <1 MHz in the temperature range from −150 °C to +120 °C. Increasing the tantalum content leads to an increase of the tunability and a shift of the point of maximum tunability to lower temperatures. ATN thick films have also been characterized up to 12 GHz in the temperature range from −30 °C to +100 °C by using coplanar waveguide resonators. A decrease of tunability to τ<1% with increasing frequency has been observed. The beginning of dielectric relaxation is observed at frequency of about 8 GHz.