Mechanical properties of rare earth stannate pyrochlores

The RE₂Sn₂O₇ series compounds (RE La, Nb, Sm, Gd, Er, Yb) with a pyrochlore structure are prepared by co-precipitation method. The bulk, shear, Young's moduli, B/G, and Poisson's ratios are calculated using density functional theory and also measured by ultrasonic resonance method. The theoretical values of lattice constants and mechanical moduli are smaller than experimental results. The electronic structures of RE₂Sn₂O₇ are analogous to RE₂Zr ₂O₇. La₂Sn₂O₇ exhibits stronger ionic bonds than others. The covalent interactions are slightly enhanced in the heavy rare earth stannate pyrochlores. The Vickers harnesses of RE₂Sn₂O₇ are measured experimentally, which are smaller than theoretical predictions.