Temperature variation of the phonon frequencies in V3Si along the [110] direction by the X-ray inelastic scattering

The investigation of the intensity of X-ray diffuse scattering by the lattice vibrations along the second-order symmetry axis in V₃Si single crystals is performed at different temperatures from 300 to 8 K and the phonon dispersion curves in this direction are determined. It is found that the phonon frequencies of all modes decrease with lowering temperature.     

Identity period and thermal expansion coefficient for rare-earth hexaborides at temperatures of 5–320 K

The temperature dependences of the lattice spacing and thermal expansion coefficient for five hexaborides MB₆ (M=Ce, Pr, Nd, Gd, and Tb) are experimentally investigated.     

Neutron diffraction study of ordering in the γ-phase of the aluminium-magnesium system

In the present work neutron diffraction study is made of the ordering effekt within the whole region of the existence of the γ-phase of the Al-Mg system. Depending on thermal treatment conditions, the order coefficient S varies from 0.15 to 0.7 for compounds containing 59 and 60 at.% Mg at temperatures ∼330 and below 150°C, respectively. – At decreased annealing temperatures the ordinate of the highest ordering is shown to approach the composition which may be approximately characterized as Al₂Mg₃. The temperature increase results in the decrease of the ordering degree, and the ordinate of the highest ordering displaces to the composition which may be expressed as Al₁₂Mg₁₇. – Kurnakov's point is determined which is lying at ∼330°C for the composition containing 59 at.% Mg.     

Formation of ceramic solid solutions in a SrTiO<Subscript>3</Subscript>-BiScO<Subscript>3</Subscript> system

X-ray structural, X-ray phase, and dilatometric analyses were used to explore specific features of the formation of solid solutions in the (1 − x)SrTiO₃−xBiScO₃ system with x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5. It was found that the synthesis of solid solutions from the initial Bi₂O₃, Sc₂O₃, TiO₂, and SrCO₃ components is accompanied by a considerable increase in the linear dimensions of the samples, depending on their composition. Solid solutions with x > 0.1 are formed through intermediate phases (Sr₅Bi₆O₁₄ at x = 0.2; Sr_0.78Bi_2.22O₄ at x = 0.3; and Sr_2.25Bi_6.75O_12.38 at x = 0.4 and 0.5). It was shown that the samples with x = 0.2, 0.3, 0.4, and 0.5 have two phases: one with a cubic Pm3m structure and one with a tetragonal I4/mcm structure.     

Parametric amplification of ultrasound in ferromagnetic piezoelectric composites at the vicinity of the orientational phase transition

Direct parametrical amplification of ultrasound was theoretically considered for the ferromagnetic/piezoelectric thin-layered structure composites, for which within the long-wavelength approach some, material specific, yet homogeneous bulk properties could be assumed. Having chosen appropriate homogeneous components, it is possible to construct a desirable composite with such properties that are absent in the starting-up “building blocks” (components).Sound frequencies are assumed to be such that only the dispersion due to magnetic subsystem is thought relevant; the piezoelectric components are set to have a nonlinear dielectric response. Presence of orientational phase transition for the ferromagnetic subsystem allows to vary frequency of a ferromagnetic resonance, and consequently to alter the dispersion at the chosen frequency of sound.While solving coupled equations describing dynamics of mechanical, magnetic and piezoelectric subsystems, an effective sound amplification for realistic values of physical parameters is shown possible.