Influence of the processing way for La3+-doping on crystal structure, microstructure, and microwave dielectric properties of Ca0.7Ti0.7La0.3Al0.3O3 ceramics.

Perovskite ceramics with a formula of Ca 0.7 Ti 0.7 La 0.3 Al 0.3 O 3 (CTLA) were produced through a conventional solid-state reaction procedure following three different La 3+ -doping methods using powders of La 2 O 3 , or La 2 O 3 /Al 2 O 3 powder mixture, or LaAlO 3 . La 3+ doping favored grain growth and densification, affected the grain size distribution, and improved the dielectric properties of the produced sintered CTLA ceramics. The doping methods had a strong influence on these properties. More specifically, doping with La 2 O 3 and La 2 O 3 /Al 2 O 3 resulted in formation of solid solution, while a secondary phase formed in the CTLA ceramics doped with LaAlO 3 , which caused a coarsening of the microstructure and lowered the La 3+ doping effects on the dielectric properties. The experimental results suggest that La 3+ doping improves the dielectric properties of the sintered CTLA perovskite ceramics, which are further enhanced by doping with Al 3+ ions in small amounts. However, further increase of Al 3+ ions content jeopardizes them. [ABSTRACT FROM AUTHOR]