Oxygen-octahedral phonon properties of xBaTiO3+(1−x)Ba(Mg1∕3Ta2∕3)O3 and xCa(Sc1∕2Nb1∕2)O3+(1−x)Ba(Sc1∕2Nb1∕2)O3 microwave ceramics

Abstract

Oxygen-octahedral A1g(O) phonons for both 1:2 ordered xBaTiO3+(1−x)Ba(Mg1∕3Ta2∕3)O3 (0≤x≤ 0.05) and 1:1 ordered xCa(Sc1∕2Nb1∕2)O3+(1−x)Ba(Sc1∕2Nb1∕2)O3 (0≤x≤ 0.25) ceramics were investigated using Raman scattering. Lineshapes of A1g(O) phonons directly reflect structural characteristic of TiO6, TaO6, ScO6, and NbO6 octahedral cages that are strongly correlated with microwave performance of the samples. The larger width of stretching A1g(O) phonon, implies poor crystalline structure and short phonon lifetime, giving us lower value of Q×f. The atomic polarizabilities of Ta5+, Ti4+, Ca2+, Sc3+, and Nb5+ have a strong influence on the structure of oxygen octahedron that dominates microwave performance of xBaTiO3+(1−x)Ba(Mg1∕3Ta2∕3)O3 and xCa(Sc1∕2Nb1∕2)O3+(1−x)Ba(Sc1∕2Nb1∕2)O3 ceramics.