Search academic texts

Registration Number

0219U102112, 0119U101820 , 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

19-12-2019

Organization

B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine

popup.description2

 The studу of smooth perovskite (001) SrTiO3 (STO) surfaces was performed to obtain detailed information on the surface atomic structure by the RHEED method from 5.5 to 300 K. Raman scattering was applied to determine the quality of STO samples. Five structural anomalies are found, depending on the temperature, indicating structural changes on the surface at different temperatures. Some of these anomalies correlate with known bulk data. If in the bulk of STO antiferrodistortive phase transition from the cubic to tetragonal phases occurs at 105 K, then similar transformation on the surface extends from 70 to 120 K. The anomalies below 7 K and about 35 K are considered in the bulk as a possible crossover between the growth of ferroelectric displacement with decreasing temperature and quantum-mechanical stabilization of growth due to the zero motion of atoms in the crystal. Other anomalies were not previously observed, they are solely related to surface layers. The differentiation of the lattice parameter values depending on the depth of electron penetration into the crystal revealed the non-monotonic nature of the change of such parameters, which is explained by the competition of the TiO2 and SrO layer contributions. On the surface two possibilities are realized, the maximum or minimum values of the parameters are reached. Minimum values are realized at temperatures where structural transformations are not observed. In zones of active structural transformation, the lattice parameters in the 1st surface layer take maximum values, which can be considered as an indicator of structural transformation in general and used as a method of detecting transformation. The information obtained is necessary to achieve a comprehensive joint experimental and theoretical detailed understanding of the structural and luminescent properties of ABO3 perovskite surfaces in order to increase their efficiency in microelectronics and catalysis.

Product Description

popup.authors

popup.nrat_date

2020-04-02