Cluster superconductivity in the magnetoelectric Pb(Fe1/2Sb1/2)O3 ceramics

We report the observation of cluster (local) superconductivity in the magnetoelectric Pb(Fe1/2Sb1/2)O3 ceramics prepared at a hydrostatic pressure of 6 GPa and temperatures 1200-1800 K to stabilize the perovskite phase. The superconductivity is manifested by an abrupt drop of the magnetic susceptibility at the critical temperature TC 7 K. Both the magnitude of this drop and TC decrease with magnetic field increase. Similarly, the low-field paramagnetic absorption measured by EPR spectrometer drops significantly below TC as well. The observed effects and their critical magnetic field dependence are interpreted as manifestation of the superconductivity and Meissner effect in metallic Pb nanoclusters existing in the ceramics. Their volume fraction and average size were estimated as 0.1-0.2% and 140-150 nm, respectively. The superconductivity related effects disappear after oxidizing annealing of the ceramics.Comment: 9 pages, 5 figure

Dielectric properties of 1:1 ternary Pb2B3+B5+O6 perovskite ceramics sintered from mechanochemically synthesized nanopowders

This study was supported by RFBR (project 17-03-01293_a) and by the Ministry of Education and Science of the Russian Federation (project 3.1649.2017/4.6)

Macroscopic and local piezoelectric properties of Pb(Mg1/3Nb2/3)O-3-PbTiO3 single crystals exhibiting giant piezoelectric response

The temperature and bias field dependences of macroscopic, measured by pulsating load method, and local, measured by piezoresponse force microscopy, longitudinal piezoelectric responses have been studied in (001)-oriented flux-grown (1 - x) Pb(Mg1/3Nb2/3)O-3-xPbTiO(3) (0.0 <= x <= 0.29) single crystals. Both types of responses exhibit a dramatic enhancement with increasing bias fields. At the same time, their temperature maxima shift from the Vogel-Fulcher temperature to the vicinity of the dielectric permittivity maximum, where the critical point in the E-T phase diagram is located. Both datasets confirm a quasicritical nature of the giant field-induced piezoelectric response in relaxor single crystals. (C) 2013 AIP Publishing LL

Тhe effect of mechanical activation on the relaxor properties of PbMg1/3Nb2/3O3 - PbFe1/2Nb1/2O3 solid solution ceramics

This study was supported by RFBR (project 17-03-01293_a) and by the Ministry of Education and Science of the Russian Federation (project 3.1649.2017/4.6)

Mossbauer study of cation substitution effect on the magnetic phase transition temperature of 0.5AFeO3-0.5NaNbO3 (A = Bi, La) solid solutions

This work was supported in part by RFBR project 19-52-53030 GFEN_a and by the Ministry of Education and Science of the Russian Federation (research projects 3.1649.2017/4.6 and 3.5346.2017/BP)