Ab initio calculations have been performed on the structural and electronic properties of perovskite-type compounds BaZrO 3 and SrZrO 3 ceramics. The Kohn-Sham equations were solved by applying the fullpotential linearized augmented-plane-wave (FP-LAPW) method. In this approach, the generalized gradient approximation was used for the exchange-correlation potential. The ground state properties such as lattice parameter, elastic constants, bulk modulus and its pressure derivative were calculated and the results are compared with previous calculations and experimental data when available. The SrZrO 3 perovskite should exhibit higher hardness and stiffness than BaZrO 3 . Furthermore, the electronic structure calculations show that these materials are weakly ionic and exhibit indirect and wide band gaps, which are typical of insulators.

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The structural and electronic properties of La2Zr2O7 and La2Hf2O7 pyrochlore compounds were investigated using the first principles full-potential linearized augmented plane wave method within the density functional theory. In this approach, the generalized gradient approximation was used for the exchange-correlation potential. We have optimized the internal structure parameter and then calculated the ground-state energy, the lattice constant, the bulk modulus, and its pressure derivative. The interatomic distances and angles were also determined. The results are in good agreement with available experimental measurements. Our electronic structure calculations predict a direct band gap at the Γ point; the nature of chemical bonding is dominated by the presence of ionic character. Furthermore, both La2Zr2O7 and La2Hf2O7 compounds are found to be insulating, which is in good agreement with experimental data.

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