Solid State Phenomena Vol. 115

Abstract: Extrinsic resonance effects observed in a low-frequency subresonant mechanical spectrometer are reported. High resolution of the mechanical spectrometer enables precise measurement of small values of the mechanical loss tangent ( tanϕ = 1- 2 × 10-4) and the apparent high values of the loss tangent detected for extrinsic resonance effects in the vicinity of the eigen frequencies of the spectrometer. Forced oscillations can be used as a ‘signal quality test’ to validate the quality of exponentially damped harmonic oscillations in the resonant mode.

Abstract: The on-line control unit is used to ensure high-accuracy computations of the logarithmic decrement. It is shown that the excitation process should be on-line low level real-time controlled during mechanical loss measurements to obtain high precision of the computations and to ensure a short-time excitation process.

Abstract: An effective Hamiltonian for the study of Sc–Nb(Ta) cation ordering in PbSc1/2Nb(Ta)1/2O3 solid solutions is worked out. To determine the parameters of the effective Hamiltonian, a nonempirical calculation is performed within an ionic-crystal model taking into account the deformation, dipole, and quadrupole polarizabilities of ions. The phase transition temperatures are calculated by the mean field, the cluster approximations, and the Monte-Carlo method. Within the same ionic-crystal model, we calculated the high-frequency permittivity, Born dynamic charges, and the phonon spectrum for completely disordered and ordered phases.

Abstract: Crystallisation processes of amorphous Cu-film on Pd(001) substrate have been investigated by molecular dynamics method. It has been established that the formed structure has tetragonal distortions; the elastic stresses caused by dimensional misfit of crystal lattices of the substrate and the film lead to the formation of complex defect structure changing during the annealing.

Abstract: We propose the Ising-like model treatment for phase transitions in pseudoquaternary solution of SDS (sodium dodecylsulfate), toluene, butanol (cosurfactant) and brine (NaCl), that was investigated by neutron spin echo spectroscopy [1] by Molle and coworkers. We compare the relaxation time and diffusion coefficient in the different kinds of droplet cellular structures in dependence on the correlation length, evaluated by lattice Monte Carlo technique.