Thermodynamic stability of BaTiO₃ (110) surfaces

Abstract

The surface stability of five terminations (BaTiO, TiO, Ba, O 2 , and O) for the polar (110) BaTiO 3 surface is systematically studied by first-principle calculations. The surface grand potential is calculated and compared, taking into account the influence of the chemical environment as function of the relative chemical potential. The complete phase diagram of the ternary system is presented. The Ba-terminated BaTiO 3 (110) surface has a surface grand potential close to that for the BaOterminated (100) surface at 0 K under Ba-rich conditions, which indicates that both (110) and (100) BaTiO 3 surfaces can exist simultaneously in perovskite ceramics. 1 Introduction Barium titanate, BaTiO 3 (BTO), is not only one of the most important ferroelectric material utilized for ceramic capacitors, ferroelectric random access memory, and piezoelectric devices [1,2], but also an important dielectric material from a technological standpoint due to its extremely high electrical permittivity. The surface structure as well as the electronic properties has a very important effect on the applications of BTO in the fields of thin films and catalysts [3,4]. Among all the orientations of the BTO crystal, the (100) surface [5][6][7] was the most extensively studied owing to its nonpolar characteristic and high stability. Relative to the well known (100) surface, however, much less is known about the (110) and (111) surfaces. The scarcity of information about these surfaces may be attributed to their polar characteristics.Although a dense and smooth (110) surface has been successfully prepared by a two-step method including the pulsed laser deposition technique in experimental [8], our knowledge on this polar surface is still limited. Only few theoretical studies [9-13] so far on BTO (110) surface structure are available. Heifets and coworkers have investigated four nonstoichiometric (110) terminations by the semiempirical shell model to reveal the structure and polarization properties, and their results showed that the relaxations and surface energies of the (110) terminations are much larger than those of the (001) terminations [9][10][11].

Ab initio Calculations of YAlO3 and ABO3 Perovskite (001), (011) and (111) Surfaces, Interfaces and Defects

“…Since supercell in our calculations should be neutral, we used a basis sets for neutral Y, Al and O atoms [47] in our YAlO 3 (001) surface calculations. Calculation details for ABO 3 perovskite B-2 polar (011) and (111) surfaces are described by us in references [11][12][13][21][22][23][24][25][26][27][28][29][30][31].…”

“…This is the main reason, why in the last twenty-five years ABO 3 perovskite (001) surfaces were worldwide intensively explored both experimentally and theoretically [9][10][11][12][13][14][15][16][17][18][19][20][21]. At the ab initio level, it is much more difficult to calculate the ABO 3 perovskite very complex, charged and polar (011) [11][12][13][21][22][23][24][25][26] and (111) surfaces [27][28][29][30][31], than the neutral (001) surfaces [9][10][11][12][13][14][15][16][17][18][19][20][21].…”

Comparative Ab initio Calculations for ABO3 Perovskite (001), (011) and (111) as well as YAlO3 (001) Surfaces and F Centers

“…In order to characterize the ABO3 perovskite and YAO chemical bonding and covalency effects, we used a classical Mulliken population analysis for the effective atomic charges Q and other local properties of the perovskite electronic structure. Additional calculation details for ABO3 perovskite very complex, polar and charged (011) and (111) surfaces we described in references [17][18][19].…”

“…The technologically important YAO (001) surfaces are much more complicated than the neutral ABO3 perovskite (001) surfaces, since they consist of alternating charged YO and AlO2 layers. Of course, it is considerably more difficult to calculate, at the ab initio level, the ABO3 perovskite very complex, polar and charged (011) [17][18][19] and (111) surfaces, than their neutral, and thereby rather simple, (001) surfaces [14][15][16].…”

Ferroelectrics: A pathway to switchable surface chemistry and catalysis

“…Polar surfaces almost always minimize their energy through some variety of atomic reconstructions rather than through purely electronic reconstructions [3,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30]. These atomic reconstructions change the stoichiometry relative to the bulk termination which, in principle, can change the surface chemistry.…”