Structure, elastic and piezoelectric properties of A3BO7 (A = Ga, Al; B = P, As) compounds: A DFT study

• Ga3AsO7 is predicted as a best piezoelectric candidate with high Curie temperature among these crystals.
• We predict three new structures and they meet the mechanical stability rule.
• The relationship between the bridging angle θ and piezoelectric constant is discussed.

A first-principles study of the structure, elastic and piezoelectric properties of A3BO7 (A = Ga, Al; B = P, As) using the density functional perturbation theory (DFPT) has been performed. The structure-properties relation was established. We found that the piezoelectric constant is highly sensitive to the distortion of crystal structures. The larger A–O–B bridging angle θ is, the smaller piezoelectric stress coefficient e15 will be. The obtained piezoelectric tensor d15 of Ga3AsO7 is −23.9 pC/N, which is more than ten times larger than the d11 of SiO2. The new finding will be useful in the applications of Ga3AsO7 in the piezoelectric devices with high Curie temperature.

Three structures of our compounds were simulated by substituting the corresponding elements, based on the structure of Ga3PO7. Then we calculated the elastic and piezoelectric constants and predicted the Ga3AsO7 is the most promising piezoelectric material of them. The structure of A3BO7 compounds. Atoms showed in (a) with A, B and O colored blue, green and red respectively as well as the bridging angle θ. Polyhedral structures were represent in (b) with BO4 tetrahedrons in blue and three AO5 trigonal bipyramids in dark gray. Besides, the direction of lattice was (a) x, (b) y and (c) z.Figure optionsDownload as PowerPoint slide