Lattice Dynamics of Alkaline-Earth Hafnates BaHfO3 and SrHfO3

M. M. Sinha

《Chinese Journal of Physics》 49卷1期 (2011/02) Pp. 301-307

並列摘要

The perovskite-type oxides have the potential to be attractive functional materials because they have various unique properties in spite of their relatively simple crystal structure. Alkaline-earth hafnates (MHfO3 with M=Ba, Sr) doped with a low level of cerium are suitable materials for high-energy nuclear medical applications. The luminescence properties of the cerium-doped hafnates have been investigated extensively; little study was done on dynamical and electronic properties of the MHfO3 host due to the unavailability of single crystal. The knowledge of the dynamical properties of the materials is very important in order to understand the possible applications of its properties in different branches of new engineering. In this work, the results of my theoretical investigation on the phonon properties of BaHfO3 and SrHfO3 in its cubic phase is being presented by applying lattice dynamical simulation method based on de Launey angular force (DAF) constant model to understand the role of phonon in this system. The calculated zone center phonon frequencies agree well with available results. The phonon spectrum of BaHfO3 and SrHfO3 are calculated along the three symmetry directions. All the phonon modes of BaHfO3 have positive frequency, indicating the stability of cubic phase in BaHfO3. Some modes of SrHfO3 are coming out negative. The imaginary frequencies are associated with unstable mode and in agreement with other calculations.