Microwave Dielectric Properties of Ba_{6- 3x}Sm_{8+ 2x}Ti₁₈O₅₄ Solid Solutions with Sr Substituted for Ba

Abstract

We have evaluated the effect of substituting Sr cations for Ba cations in solid solutions with a tungsten bronze-type structure used in microwave dielectric resonators. Instead of Ba 6-3 x Sm 8+2 x Ti 18 O 54 solid solutions formula, the structure formula is presented as (Sm 8+2 x Ba 2-3 x )(Ba 4 )Ti 18 O 54 for the range of 0≤ x ≤2/3 and (Sm 9.33+2( x -2/3) )(Ba 4-3( x -2/3) )Ti 18 O 54 for 2/3 ≤ x ≤1. The quality factor Q \cdotp f has been improved based on the substitution of 0.2 Sr ions for 0.2 Ba ions in perovskite blocks in (Sm 9.2 Ba 0.2 )(Ba 4 )Ti 18 O 54 where x =0.6. This composition has the best dielectric quality in the solid solution series, because the substitution reduced the strain caused by the Ba ions. The relationship between the lattice parameters and the microwave dielectric properties is also presented.