A5013324432- Glass properties and applications
- Ferroelectric and Piezoelectric Materials
- Solid-state spectroscopy and crystallography
- Acoustic Wave Resonator Technologies
- X-ray Diffraction in Crystallography
- Material Dynamics and Properties
- Multiferroics and related materials
- Theoretical and Computational Physics
- Optical and Acousto-Optic Technologies
- Microwave Dielectric Ceramics Synthesis
- Metallic Glasses and Amorphous Alloys
- Material Properties and Applications
- Material Science and Thermodynamics
- Dielectric materials and actuators
- nanoparticles nucleation surface interactions
- Iron oxide chemistry and applications
- Pigment Synthesis and Properties
- Zeolite Catalysis and Synthesis
- Nuclear materials and radiation effects
- High-pressure geophysics and materials
- Mineralogy and Gemology Studies
- Surface Roughness and Optical Measurements
- Aerogels and thermal insulation
- Magnetic Properties and Synthesis of Ferrites
- Advanced Condensed Matter Physics
Ioffe Institute
2016-2025
Peter the Great St. Petersburg Polytechnic University
2011-2020
Physical and Technical Institute
2011-2020
Institute of Physics
2020
Russian Academy of Sciences
1998-2016
Physico-Technical Institute
1989-2014
Physicotechnical Institute
2006
Petersburg Nuclear Physics Institute
1975-2004
Abstract Peculiarities of phase transitions in disordered perovskite-like crystals—PbMg1/3 Nb2/3 O3 (PMN) and Na1/2 Bi1/2 TiO3 (NBT) have been studied by neutron scattering. The strong quasielastic scattering (QES) related to ferroelectric critical fluctuations has observed instead expected inelastic soft phonon mode. wavevector dependence this diffuse well described Ornstein-Zernice formula. correlation length temperature resembling that spin-glasses obtained. history dependent effects...
The phase transition from tetragonal to rhombohedral in sodium bismuth titanate (NBT) is studied by means of neutron scattering. It found that the has incommensurate modulation along four-fold axis precursor phase. appearance discussed on symmetry grounds framework phenomenological theory transitions.
The ${\mathrm{N}\mathrm{a}\mathrm{N}\mathrm{O}}_{2}$ nanocomposite ferroelectric material in porous glass was studied by neutron diffraction. For the first time, details of crystal structure including positions and anisotropic thermal parameters were determined for solid material, embedded a matrix, ferro- paraelectric phases. It is demonstrated that phase consistent with bulk data, but above transition temperature giant growth amplitudes vibrations observed, resulting formation ``premelted...
Whereas the $^{23}\mathrm{Na}$ spin-lattice relaxation rate ${T}_{1}^{\ensuremath{-}1}$ of microconfined ${\mathrm{NaNO}}_{2}$ in ferroelectric phase is similar to one bulk ${\mathrm{NaNO}}_{2}$, there a striking difference paraelectric phase. Instead decreasing, here increases with increasing temperature and much larger than bulk. The due self-diffusion ``premelted state'' induced by microconfinement. This also explains previously observed giant growth dielectric permittivity confined more...
By neutron diffraction it was shown that Pb nanoparticles confined within a porous glass have an elongated form along the [111] direction which coincides with pore axis. The mean-square displacements and perpendicular to this are different. When approaching melting point displacement axis increases while in remains nearly constant as limited by walls. temperature dependence of isotropic greatly differs from bulk. softening atomic vibrations due lattice expansion confinement is negligible contrast
Abstract In this paper the results of dielectric investigation nanoconfined NaNO2 is presented. The phase transition shifted to lower temperatures. Only one can be seen in spectra and intermediate incommensurate suppressed. increase frequency dependent permitivity on heating mainly result a conductivity effects. relaxational soft mode contribution as well present, but small compared contribution. Such huge caused by premelting phase, which visible even at temperatures below Acknowledgments...
This contribution is devoted to the study of morphology and magnetic properties sodium borosilicate glasses with different concentrations (15, 20, 25 wt.%) α -Fe 2 O 3 in an initial furnace charge. These were prepared by a melt-quenching method. For all coexistence drop-like two-phase interpenetrative structures observed. The most part drop structure formed self-assembling iron oxides particles. All types demonstrate can be used for preparation porous matrices nanometer through dendrite...
Dielectric properties and temperature evolution of the crystal structure nanocomposites on basis porous glasses KNO3 embedded into pores have been studied heating cooling. It is shown that stability ferroelectric phase depends nanoparticle sizes prehistory sample preparation measurement procedure. The interval, where exists, increases decreasing size. In composite with average pore diameters 7 nm, becomes stable down to 100 K after first heating–cooling circle.