Important Perovskite Oxide Research Articles

Freestanding perovskite oxide monolayers as two-dimensional semiconductors

It is highly desirable to search for promising two-dimensional (2D) monolayer materials for obtaining deep insight of 2D materials and developing device applications. We use first-principles method to investigate tetragonal perovskite oxide monolayers as 2D materials, and find three stable freestanding 2D monolayer materials from important perovskite oxides (ABO3), namely SrTiO3, LaAlO3, and KTaO3, denoting them as STO-ML, LAO-ML, and KTO-ML. Such an oxide monolayer consists of one AO and one BO2 atomic layers. Further study shows that the three monolayers are 2D wide-gap semiconducotors, and there is a large electrostatic potential energy difference between the two sides, reflecting a large out-of-plane dipole, in each of the monolayers. We also investigate optical properties of the three monolayer semiconductors and compare them with graphene and MoS2 monolayer. These make a series of 2D monolayer materials, and should be useful in novel electronic and optoelectronic devices considering emerging phenomena in perovskite oxide heterostructures.

How heteroepitaxy occurs on strontium titanate.

In traditional models of heteroepitaxy, the substrate serves mainly as a crystalline template for the thin-film lattice, dictating the initial roughness of the film and the degree of coherent strain. Here, performing in situ surface x-ray diffraction during the heteroepitaxial growth of LaTiO3 on SrTiO3 (001), we find that a TiO2 adlayer composed of the R33.7° and R45.0° reconstructions is a highly active participant in the growth process, continually diffusing to the surface throughout deposition. The effects of the TiO2 adlayer on layer-by-layer growth are investigated using different deposition sequences and anomalous x-ray scattering, both of which permit detailed insight into the dynamic layer rearrangements that take place. Our work challenges commonly held assumptions regarding growth on TiO2-terminated SrTiO3 (001) and demonstrates the critical role of excess TiO2 surface stoichiometry on the initial stages of heteroepitaxial growth on this important perovskite oxide substrate material.

Structural and Optical Properties of La1-xSrxTiO3+δ.

La1−xSrxTiO3+δ has attracted much attention as an important perovskite oxide. However, there are rare reports on its optical properties, especially reflectivity. In this paper, its structural and optical properties were studied. The X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and spectrophotometer were used to characterize the sample. The results show that with increasing Sr concentration, the number of TiO6 octahedral layers in each “slab” increases and the crystal structure changes from layered to cubic structure. A proper Sr doping (x = 0.1) can increase the reflectivity, reaching 95% in the near infrared range, which is comparable with metal Al measured in the same condition. This indicates its potential applications as optical protective coatings or anti-radiation materials at high temperatures.

ChemInform Abstract: Single Step Synthesis of GdAlO3 Powder.

AbstractThe title compound is an important perovskite oxide with applications as phosphor, scintillator, and as a potential host system for materials with oxygen ion conductivity.

Theoretical investigation of {1 1 0} generalized stacking faults and their relation to dislocation behavior in perovskite oxides

Studies of generalized stacking fault energy surfaces, or γ-surfaces, provide a convenient and efficient source of information on possible dislocation dissociation mechanisms and favorable glide systems. We carried out an extensive theoretical investigation of the {1 1 0} γ-surface for three technologically important perovskite oxides SrTiO 3, BaTiO 3, and PbTiO 3. The calculations were performed using both a highly accurate first-principles density functional theory approach and simple empirical interatomic potentials. The main characteristic features common to all {1 1 0} γ-surfaces are the low energy path along the 〈 1 1 ¯ 0 〉 direction and the existence of a single local energy minimum along this path. This minimum corresponds to an antiphase boundary that has been observed experimentally in dissociated dislocation cores in various perovskites. The energy profiles obtained using the empirical potentials agree qualitatively well with the first-principles results but there are significant quantitative discrepancies. This comparison provides a valuable insight into the quality and limitations of empirical potentials for atomistic simulations of dislocations and other extended defects in these materials.

Microwave preparation and sintering of industrially important perovskite oxides: LaMO3 (M = Cr, Co, Ni)

Perovskite oxides LaMO3 (M = Cr, Co, Ni), have been successfully prepared using microwaves of 2.45 GHz. Microwave preparation is rapid, clean and energy efficient. Preparation of LaCrO3, LaCoO3 and LaNiO3 has been achieved in 3 min, 5 min and 10 min respectively. Direct reaction between component oxides is used for the preparation of LaCrO3 and LaCoO3, whereas nitrates are used as starting materials for LaNiO3 preparation. Products have been characterized using XRD, IR spectroscopy and SEM. Their dc electrical conductivity has also been studied and their fracture behaviour has been examined. All three microwave prepared oxide powders are of submicron size. These perovskite oxides have been sintered to very high densities using microwaves. Possible mechanisms of the microwave–material interaction both during preparation and during sintering have been discussed.