The effect of partial isovalent substitution in the A-sublattice on MW properties of materials based on Ba6–xLn8+2x/3Ti18O54 solid solutions

Investigations of materials based on the three systems: (Ba1–yPby)6–xLa8+2x/3Ti18O54, (Ba1–yPby)6–xNd8+2x/3Ti18O54, and (Ba1–yCay)6–xLn8+2x/3Ti18O54 revealed that a partial isovalent substitution in cation sublattices allows the control of the electrophysical parameters of microwave dielectrics. The investigations were carried out over a wide range of x values. Data on the relationship between the crystal-cell parameters and the microwave dielectric properties (ε, Q, and tf) have been obtained and related to the size of the isovalent ion residing at crystallographic sites in the A-sublattice. Based on the data obtained, a non-random distribution of Ca2+ and Pb2+ ions on different A-sites as a function of their concentration in different systems was concluded. Various temperature-stable microwave dielectrics, based on the above three systems, have been synthesized and shown to exhibit excellent MW properties.