Further ordering structural investigation of Ba((Co,Zn,Mg)1/3Nb2/3)O3 perovskites by Raman spectroscopy

Correlations among the Raman vibration modes, ordering structures and dielectric properties have been established through further ordering structural investigation of Ba((Co0.6-x/2Zn0.4-x/2Mgx)1/3Nb2/3)O3 ceramics by Raman spectroscopy. Meanwhile an in-depth understanding of Raman spectroscopy for 1:2 ordered Ba(B′1/3B″2/3)O3 perovskites has been gained. An approximate 1:1 ordered structure composed of alternate Nb5+-rich and Nb5+-dificient layers is detected by transmission electron microscopy observation, confirming that the four main Raman peaks of 1:2 ordered structure arise from the nanoscale regions of 1:1 ordering in B-site sublattice. As x increases, Ba-related and Nb-related phonons show growing lifetime with the increase of ordering degree and Qf values. Simultaneously, oxygen vibration along c axis (Eg(4) (O) mode) is favored, while the vibration in ab plane (Eg(3) (O) mode) weakens since 1:2 ordering forms along the c-axis of ordered structure. The lifetime of the oxygen-octahedron stretch A1g(4) (O) mode (∼788 cm−1) is supposed not only influenced by the ordering domain size, but also the micro-defects such as ordering domain boundaries.