Search academic texts

Information × Registration Number 0220U104324, 0120U103279 , R & D reports Title Low temperature characterization and ab initio calculations of anomalous behavior of structural, luminescent and conductivity properties of ABO3 perovskite surfaces popup.stage_title Head Krainyukova Nina V., Кандидат фізико-математичних наук Registration Date 16-12-2020 Organization B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine popup.description2 The smooth and nanostructured perovskite (001) surfaces of SrTiO3 were studied by the reflection high-energy electron diffraction method in the temperature range 5-300 K to obtain detailed information on a surface atomic structure. Spectroscopic characteristics of crystalline samples were analyzed to establish their quality. Five structural anomalies depending on temperature have been revealed on the surface at different temperatures. Three of these anomalies correlate with the known bulk data but with differences specific for a surface. About 105 K the antiferrodistortive phase transition from the cubic to tetragonal structure is realized, but unlike a bulk it extends on a surface on a temperature range from 70 to 120 K. The observed anomalies at temperatures below 7 K, and also about 35 K are considered in a bulk as a possible crossover between the growth of the ferroelectric displacement with decreasing temperature and the quantum-mechanical stabilization of this growth due to the significant zero-point atomic motion. The other two anomalies have not been observed before and are related exclusively to the surface layers. Differentiation of the lattice parameters depending on the depth from a surface revealed the effect of contraction of a crystal lattice in the plane of the (001) surface of strontium titanate. This effect results in slight incommensurability between the lattice parameters in the surface layers and the bulk values, which relaxes due to the edges of the steps and the mismatch dislocations. In intervals of active structural transformation, the lattice parameters on the surface, as a rule, attain the maximum values that can be used as a method of detecting structural transformation. The surface ordered nanostructures formed on etched surfaces are analyzed as well. Intrinsic ordered nanostructures on single-crystal surfaces open new prospects for applications when a controlled architecture of nanoscale formations is required.  Product Description popup.authors popup.nrat_date 2020-12-16 Close