| Abstract
| - We predict the occurrence of large ferroelectric polarization and piezoelectricity in the hypotheticalperovskite-structure oxides, bismuth aluminate (BiAlO3) and bismuth gallate (BiGaO3), using densityfunctional theory within the local density approximation. We show that BiGaO3 will have a similar structureto PbTiO3, although with much stronger tetragonal distortion and therefore improved ferroelectricproperties. Likewise, BiAlO3 shares structural characteristics with antiferrodistortive PbZrO3, but it isalso a ferroelectric with large polarization. Therefore, we propose the Bi(Al,Ga)O3 system as a replacementfor the widely used piezoelectric material, Pb(Zr,Ti)O3 (PZT), that will avoid the environmental toxicityproblems of lead-based compounds. Finally, we show that, in both BiAlO3 and BiGaO3, the large distortionsfrom the prototypical cubic structure are driven by the stereochemical activity of the Bi lone pair.
- Two new ferroelectric materials, BiAlO3 and BiGaO3, are predicted using density functional calculations. Large ferroelectric polarizations and piezoelectric responses are obtained for both materials, a result of the strong stereochemical activity of the Bi lone pairs. A Bi(Ga,Al)O3 solid solution is proposed as a lead-free alternative to the widely used piezoelectric, Pb(Zr,Ti)O3.
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