Phase composition and microwave dielectric properties of Ca0.128Ba0.032Sm0.46Li0.3TiO3 ceramics with alumina addition.

Ca 0.128 Ba 0.032 Sm 0.46 Li 0.3 TiO 3 - x wt.% Al 2 O 3 microwave dielectric ceramics with temperature stability were prepared by the traditional solid-state reaction method. The effects of Al 2 O 3 doping on phase composition, micromorphology, and microwave dielectric properties of Ca 0.128 Ba 0.032 Sm 0.46 Li 0.3 TiO 3 ceramics were investigated. X-ray diffraction results showed that no other phase was introduced by doping, and the diffraction peaks of all the ceramics could be indexed by standard JCPDS cards of No.42−0423 (CaTiO 3) and No.43−0235 (BaSm 2 Ti 4 O 12). To further study the effects of Al 2 O 3 doping on microstructure and lattice vibration of Ca 0.128 Ba 0.032 Sm 0.46 Li 0.3 TiO 3 ceramics, the structural refinement and Raman spectroscopy techniques were also adopted. Doping Al 2 O 3 decreased the lattice constant of CaTiO 3 -phase solid solution, modified the morphology and improved microwave dielectric properties of the ceramics. When sintered at 1300 °C for 4 h, the ceramics with 0.9 wt.% Al 2 O 3 showed excellent microwave dielectric properties: ε r = 87.9 ± 0.4, Q × f = 6671 ± 103 GHz, and τ f = -1.2 ± 0.9 ppm/℃. [ABSTRACT FROM AUTHOR]