Study of palladium nanoparticles synthesized in alkali borosilicate glass pores by the X-ray line shift method

Metallic Pd synthesized in porous glass with an average pore diameter of 7 ± 2 nm has been studied using the X-ray diffraction and X-ray line shift methods for the first time. The irregular dependence of the reflection width in X-ray patterns on the diffraction angle has been revealed. This can be caused by crystallite growth mostly in the [111] direction or by tetrahedral distortions of the fcc lattice. The shift (difference in energy) of K _α1 lines (ΔE _α1 = 19 ± 2 meV) for nanostructured Pd in comparison with the bulk material is first detected. The detected effect is considered within the assumption of the palladium electron redistribution between Pd 5s- and 4d-bands.     

Effect of Restricted Geometry on the Structure and Phase Transitions in Potassium Nitrate Nanoparticles

The effect of restricted geometry and thermal prehistory of sample preparation on phase transitions in nanocomposites on base of porous glasses with average pore diameters 7 and 46 nm filled by potassium nitrate have been studied by X-rays and neutron diffraction. The nanoparticle sizes have been determined and phase diagrams (on cooling) for these nanoparticles have been described. It is shown that there is a critical nanoparticle size in the interval from 30 till 20 nm, at which in nanocomposite the ferroelectric phase is realized only regardless of preparation method.     

Investigation of longitudinal vibrations of -O-H groups in chrysotile asbestos by neutron scattering and polarized infrared spectroscopy

The specific features of the vibrational spectra of chrysotile asbestos, which is a natural mineral that represents a system of closely packed tubular fibers with an outer diameter of ∼30 nm, an inside diameter of ∼5 nm, and a length up to a centimeter and more, have been investigated using neutron scattering and polarized infrared spectroscopy. This material can serve as a natural matrix for the preparation of nanostructures by filling channels with various materials.     

Atomic dynamics of lead embedded into nanoporous glass

The thermal atomic vibration spectrum of lead nanostructured in porous glass with an average pore size of 7 nm and the thermal vibration spectrum of conventional bulk lead (taken for comparison) are measured using inelastic neutron scattering. The density of states in the phonon spectrum of lead nanoparticles is found to exceed the density of states in the spectrum of bulk lead at both low (E < 2.5 meV) and high (E > 9.5 meV) energies. These data are used to propose a model for the structure of a porous glass-lead nano-composite.     

Atomic motion in Se nanoparticles embedded into a porous glass matrix

By neutron diffraction it was shown that nanostructured Se confined within a porous glass matrix exists in a crystalline as well as in an amorphous state. The spontaneous crystallization of crystalline Se from confined amorphous phase was observed. The root-mean-square amplitudes of the atomic motions in the bulk as well as in confinement are found to be essentially different in a basal plane and in the perpendicular direction along the hexagonal axis. The atomic motions in the confined Se differ from the atomic motions in the bulk at low temperatures. The results shows an unusual “freezing" of the atomic motion along the chains, while the atomic motions in the perpendicular plane still keep. This “freezing" is accompanied by the deformation of nanoparticles and the appearance of inner stresses. This effect is attributed to the interaction of confined nanoparticle with the cavity walls.     

Structure and dielectric response of Na<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>K<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>NO<Subscript>2</Subscript> nanocomposite solid solutions

This paper reports on the results of the investigation into the thermal evolution of the structure and dielectric properties of Na_{1 ? x} K _x NO₂ solid solutions (x = 0, 0.05, 0.10) embedded in porous glass with an average pore diameter of 70 ± 10 Å in the range 300–447 K, i.e., in the ferro-and paraelectric phases. The structural properties of the bulk and nanostructured materials are compared. It is shown that the introduction of small amounts of potassium brings about a noticeable change in the intensity ratio of the elastic Bragg peaks, while leaving the space group characterizing the structure of these nanocomposites unaffected. An increase in the potassium fraction does not result in a substantial decrease in the phase transition point. Measurements of the dielectric response have revealed that an increase in the potassium content gives rise to a marked “hardening” of the lattice in the premelting state, which reduces dielectric losses.     

Temperature evolution of copper oxide nanoparticles in porous glasses

The temperature evolution of copper oxide nanoparticles in the temperature range of 1.5–250 K has been investigated by thermal-neutron diffraction. CuO particles were obtained by Cu(NO₃)₂ · 3H₂O decomposition directly in the pores of porous glass with an average pore diameter of 7 nm. The characteristic nanoparticle size and linear thermal expansion coefficients have been determined.     

Internal structure of magnetic porous glasses and the related ferroelectric nanocomposites

Physics of the Solid State - The internal structure of empty porous micro- and macroporous magnetic glasses and the related nanocomposites containing NaNO2 and KNO3 embedded in pores of the glasses...     

Ferroelectricity in nanocomposites based on porous glass with inclusions of NaNO<Subscript>2</Subscript>

The dielectric nonlinearity and pyroeffect in matrix composite based on porous glass with inclusions of sodium nitrite are investigated. It is found that the composite polarization turns to zero at a temperature below that of the phase transition in the bulk NaNO₂. The obtained dependence of the pyrocoefficient on temperature also corroborates the existence of the phase transition in sodium nitrite nanoparticles included in the porous matrix.