Abstract

The electronic structural and surface acoustic wave (SAW) properties of Ca₃Ga₂Ge₃O₁₄ (CGG), Sr₃Ga₂Ge₃O₁₄ (SGG) and Pb₃Ga₂Ge₃O₁₄ (PGG) crystals have been investigated. The first-principle calculations show that CGG and SGG have similar electronic structure properties, the remarkable difference between PGG and another two crystals is the absence of lower part of valence band. Both the calculated effective charges and bond populations show that there is considerable covalency between cations and O atom. The calculated SAW results show that PGG has the lowest velocities because of its highest density, SGG has the highest electromechanical coupling coefficients, CGG and SGG have more zero power flow angles and negligible diffraction angles than PGG crystal. Some promising cut-types such as Y-cut 148^o of SGG, X-cut 154^o of CGG and Y-cut 0^o of PGG have been selected for their SAW applications.

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