A systematic study of ideal and double layer reconstructions of ABO₃(001) surfaces (A = Sr, Ba; B = Ti, Zr) from first principles

Abstract

We conducted a comparative study of various reconstructions for the (001) surfaces of SrTiO(3), BaTiO(3), SrZrO(3) and BaZrO(3) perovskites through calculations within the density functional theory. The atomic structure, the thermodynamic stability and the charge distribution of ideal AO or BO(2) terminations, as well as the so-called AO or BO(2) double layer reconstructions were analysed, and it was found that of all the BO(2) double layer reconstructions the most stable are the (2 × 2) and the (√2 × √2) ones. This is mainly due to stress release through the formation of long B-chains. On Ti-based perovskites, these double layer reconstructions were found to be thermodynamically stable, which was not the case for Zr-based perovskites, for which AO terminations dominated most of the stability domain. We also found that the BO(2) double layer reconstructions are accompanied by a substantial charge redistribution, with an almost neutral surface plane. This charge redistribution has important consequences for the reactivity and the behaviour of the electric field close to the surface.

Surface Relaxations, Surface Energies and Electronic Structures of BaSnO3 (001) Surfaces: Ab Initio Calculations

“…These results are in good qualitative agreement with other Ab initio calculations dealing with ABO 3 (001) surfaces. [11][12][13][14][26][27][28][29][30] In addition, the shrinkage in the interlayer distance, Dd 1-2 , of the SnO 2 -terminated surface is larger than that of the BaO-terminated surface, which disagrees with what happens in the case of the (001) surface. Moreover, it is shown that the amplitude of the surface rumpling on the SnO 2 -terminated surface of 3.742% is slightly larger than that of 3.348% for the BaO-terminated surface, …”

“…9,10 Unlike the bulk materials, the surfaces of the materials exhibit completely different physical and chemical features. 11 Hence, it is essential to study the material surfaces and the linked physical and chemical properties in order to understand such phenomena occurring at the material surfaces.…”

“…Over the last decade, a large number of theoretical investigations have been carried out through first-principles density functional theory for the calculations of ABO 3 surfaces, 11,12 including atomic relaxations of AO-and BO 2 -terminated ABO 3 (001) terminations, their surface energies and electronic structures. For instance, Eglitis 12 conducted ab initio calculations on BaZrO 3 (001) surfaces and found that all the first-layer atoms move inward for both BaO-and ZrO 2 -terminated BaZrO 3 (001) surfaces.…”

Structural and electronic properties of cubic KNbO3 (001) surfaces: A first-principles study

“…The largest atomic relaxations of BaO-terminated and TiO 2 -terminated cubic BaTiO 3 (0 0 1) surfaces are on the first-layer atoms [11]. Iles et al [1] conducted a comparative study of various reconstructions for the (0 0 1) surfaces of SrTiO 3 , BaTiO 3 , SrZrO 3 and BaZrO 3 perovskites and showed that the largest atomic displacements for BO 2 terminated surfaces are in the first-layer oxygen atoms. This tendency is in correspondence with the present calculations of NbO 2 terminated KNbO 3 (0 0 1) surfaces.…”

“…In contrast to the bulk, thin films have larger surfaces. In addition, surfaces of ferroelectric materials are typically the first natural interface between a given material and the environment [1]. Therefore, it is particularly important to investigate the surface structure of ferroelectric thin films and the associated physical and chemistry properties affected by surfaces.…”