Theoretical Prediction of New High-Performance Lead-Free Piezoelectrics

Abstract

We predict the occurrence of large ferroelectric polarization and piezoelectricity in the hypothetical perovskite-structure oxides, bismuth aluminate (BiAlO 3 ) and bismuth gallate (BiGaO 3 ), using density functional theory within the local density approximation. We show that BiGaO 3 will have a similar structure to PbTiO 3 , although with much stronger tetragonal distortion and therefore improved ferroelectric properties. Likewise, BiAlO 3 shares structural characteristics with antiferrodistortive PbZrO 3 , but it is also a ferroelectric with large polarization. Therefore, we propose the Bi(Al,Ga)O 3 system as a replacement for the widely used piezoelectric material, Pb(Zr,Ti)O 3 (PZT), that will avoid the environmental toxicity problems of lead-based compounds. Finally, we show that, in both BiAlO 3 and BiGaO 3 , the large distortions from the prototypical cubic structure are driven by the stereochemical activity of the Bi lone pair.

Electronic structure, ferroelectric properties, and phase stability of BiGaO3 under high pressure from first principles

“…However, in all cases this overestimation is less than 5 % which is typical for GGA-PBE functional. The tetragonal P4mm phase has a large tetragonality (c/a = 1.286), which is in good agreement with the previous theoretical report (c/a = 1.30) [3]. The effective tetragonality in monoclinic Cm phase is given by 2H2c/(a ?…”

“…In case of BiGaO 3 , there is only one experimental report so far [10]. We believe that future experiments will give more decisive answer about the symmetry of high-pressure phases of BiGaO 3 .…”

“…In addition, we have also investigated five space groups: Pm-3m, P4mm, R3m, C2/m, and R-3c, which have not been observed in experiment but were investigated theoretically in the Ref. [3]. Experimentally established structural data from Refs.…”

“…The stereochemically active 6s 2 lone pair on the Pb 2? or Bi 3? ions is responsible for the large ion off-centering in Pb-and Bi-based perovskites and, as a result, the large ferroelectric polarization. Among bismuth perovskite oxides, BiGaO 3 has been studied extensively since the first theoretical report [3], in which large ferroelectric polarization was predicted with the value of 151.9 lC/cm 2 for tetragonal ground-state structure (space group P4mm). A high-pressure and high-temperature technique was used to prepare BiGaO 3 samples [4].…”

“…There are also several studies of the perovskite cubic phase of BiGaO 3 [14][15][16][17]. But to our knowledge, there are no theoretical reports concerning pressure-induced structural phase transitions for BiGaO 3 . Study of high-pressure phases could shed light on physical properties of phases which appear in different solid solutions of BiGaO 3 systems [6][7][8][9][18][19][20].…”