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The properties of nanoparticles are determined by their size and structure. When exposed to external pressure P, their structural properties can change. The improvement or degradation of the properties of the samples depending on time is particularly interesting. The knowledge of the influence of structural-size effect, aging time, and pressure on the behavior of the compounds is essential for fundamental and applied purposes.Therefore, the first attempts have been made to shed light on how the functional properties of the Mn-containing perovskites change depending on them. The nanoparticles of different sizes, from 20 to 70 nm, have been obtained. After 3 years, their structural properties underwent significant changes, including an increase in particle size, bandwidth, and microstrains, as well as a reduction in dislocation density.The greatest change in the structure is observed for the smallest nanoparticles. The phase transition temperatures increase with nanoparticle size, time, and pressure. The aging time has the strongest influence on the changing Curie temperature for the smallest and most magnetically inhomogeneous nanoparticles with dTc/dP = 100 K / GPa. Conversely, the structural-size effect and external pressure have the greatest influence on the biggest and most magnetically uniform nanoparticles with dTc/dP = 91 and 16 K / GPa, respectively. After 3 years, the biggest nanoparticles demonstrate the most stable phase transition temperatures with improved magnetocaloric parameters near room temperature. These structural-size effect, aging time, and pressure are powerful instruments to tune the phase transition temperatures and magnetocaloric effect of the nanoparticles. These outcomes may have implications for the whole class of perovskites and could initiate a new mainstream., Comment: 57 pages, 33 figures

Simultaneous study of magnetic and electrocatalytic properties of cobaltites under extreme conditions expands understanding of physical and chemical processes proceeding in them with the possibility of their further practical application. Therefore, La0.6Sr0.4CoO3 (LSCO) nanopowders have been synthesized at different annealing temperatures tann = 850, 875, 900 C, and their multifunctional properties have been studied comprehensively. As tann increases, the rhombohedral perovskite structure of the LSCO becomes more single-phase, whereas average particle size and dispersion grow. Co ions are in mixed valence states, including major Co3+ and Co4+ components. It has been found that the LSCO-900 shows two main Curie temperatures, TC1 and TC2, associated with a particle size distribution. As an external hydrostatic pressure P increases, average and increase from 253 and 175 K under ambient pressure to 268 and 180 K under P = 0.8 GPa, respectively. At the same time, the antiferromagnetic temperature TAFM and blocking temperature TB also increase from 145 and 169 K to 158 and 170 K, respectively. The increment of for the smaller and bigger particles is sufficiently high and equals 10 and 13 K/GPa, respectively. The magnetocaloric effect in the LSCO-900 nanopowder is relatively weak but with an extremely wide peak > 50 K that makes this composition interesting to be used as one of the components of the composite expanding its working temperature window. Moreover, all LSCO samples showed excellent electrocatalytic performance for the overall water splitting (OER) process (overpotentials only 265-285 mV at a current density of 10 mA/cm2) with minimal values for LSCO-900. Based on the XPS data, it was found that the formation of a dense amorphous layer on the surface of the particles ensures high stability as a catalyst (at least 24 h) during electrolysis in 1 M KOH electrolyte., Comment: 40 pages, 19 figures, 9 tables, 90 references, article

The results of a study of magnetoactive elastomers (MAEs) consisting of an elastomer matrix with embedded ferromagnetic particles are presented. A continuous critical bending induced by the magnetic field, characterized by a critical exponent for the bending magnitude, and the derivative of which has a singularity in the critical region is reported for the first time. The mechanical stability loss and the symmetry reduction of the magnetic state, which are interrelated with each other, take place at the critical point. The magnetization in the high-symmetric state (below the critical point) is directed along the magnetic field and the torque is absent. Above the critical point, the magnetization and the magnetic field are noncollinear and there arises a torque, which is self-consistent with the bending. The magnetic field dependence of the MAE bending was found to have a hysteresis, which is associated with the magneto-rheological effect. The shape memory effect was also obtained for the MAE bending in a cycle consisting of magnetization, cooling (at H=/0), and heating (at H=0). The influence of the critical glass transition temperature of the matrix, as well as its melting/solidification temperature, on the magnetic shape memory effect was studied., Comment: 12 pages, 7 figures, now the paper is under review to Smart Materials and Structures (SMS-111130.R1), Awaiting Referee Reports. We want to protect our data and results

A magnetoactive elastomer (MAE) consisting of single-domain La0.8Ag0.2Mn1.2O3 nanoparticles with a Curie temperature close to room temperature (TC = 308 K) in a silicone matrix has been prepared and comprehensively studied. It has been found that at room temperature and above, MAE particles are magnetized superparamagnetically with a low coercivity below 10 Oe, and the influence of magnetic anisotropy on the appearance of a torque is justified. A coupling between magnetization and magnetoelasticity has been also established. The mechanisms of the appearance of magnetoelasticity, including the effect of MAE rearrangement and MAE compression by magnetized particles, have been revealed. It has been found that the magnetoelastic properties of MAE have critical features near TC. The magnetoelastic properties of MAE disappear at T > TC and are restored at T < TC. This makes it possible to use MAE at room temperature as a smart material for devices with self-regulating magnetoelastic properties., Comment: 31 pages, 9 figures

The paper contains a short description of the scientific papers of Professor Boris Ya. Sukharevsky on condensed matter physics. His basic scientific activity was related to following directions: structural vacancies concept; influence of point defects on statics and kinetics of phase transitions; DNA crystallization and low-dimensional systems properties; phase transitions in Jahn-Teller crystals; Thermophysics of superconductors e.a. The list of most essential papers of Prof. B.Ya. Sukharevsky is included., Comment: 16 pages, 53 references