Structural and vibrational approach on the luminescent BZO ceramic doped with Ce and Hf: A experimental/theoretical study.

Reference Presenter Authors
06-163 Mário Lúcio Moreira Moreira, M.L.(Universidade Federal de Pelotas); Ururi, J.L.(Universidade Federal de Pelotas); Cava, S.(Universidade Federal de Pelotas); Raubach, C.W.(UNIVERSIDADE FEDERAL DE PELOTAS);

In this study, the photoluminescence (PL) of BaZrO3 Perovskite bulk host lattice is increased by the Hafnium addition. However the emission is too narrow, then Ce-doping was performed to look for wider PL emission. In this context the luminescence was enlarged as a result of the decrease of its intensity as Ce-doping increases, until it disappears with 4% of cerium concentration. The replacement of cerium on a site is a new possible electronic transitions since that luminescence is narrow and poor. This unexpected result requires an additional computational approach using CRYSTAL09 to make this simulation based on "all electron base-sets" and pseudopotentials according to the convergence criteria. Firstly, the convergence of supercells was optimized whitout Hf and Ce and subsequently for each one separately and then approached together. Then, the Hf content promotes lattice distortions that emerge to vibrational modes to be evaluated from theoretical simulation. The same interpretation was also evaluated to Ce. Both cerium and hafnium inset 5d states at conduction band at the same region. This superposition of states can help to explain the decrease of luminescence with Ce contend increases, associated with quenching of concentration of Cerium. Additionally synthesized BaZrO3 samples of Ce and Hf-doped do not present additional phase detected by X-ray diffraction. Other unexpected result is the first order active Raman modes observed for cubic BaZrO3 Perovskite, thus a computational model is necessary to understand the origin of this vibrations. This theoretical point of view is able to understand physical phenomena in order to predict future experimental results.

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