Initial stages of diffusion and phase formation in Sc/Si layered systems

Tue, 01 Jan 2008 00:00:00 GMT

Initial stages of diffusion and phase formation in Sc/Si layered systems Voronov, D.L.; Zubarev, E.N.; Kondratenko, V.V.; Pershun, Yu.P.; Sevryukova, V.A.; Bugayev, Ye.A. Kinetics of phase formation Sc/Si multilayers and Si/Sc/Si three-layers within the temperature range of 130-400°C has been studied by cross-sectional transmission electron microscopy and small-angle X-ray reflectometry. Growth of ScSi silicide governed by diffusion kinetics was observed at all temperatures. Two growth stages of nonparabolic and parabolic behavior were revealed. Initial nonparabolic stage is characterized by higher diffusion coefficient, which decreases during annealing in 20 times due to silicide structural relaxation. After annihilation of excess free volume a transition to parabolic growth takes place. Parameters of interdiffusion (activation energy E ≈1 eV and pre-exponential factor D₀ = 4.10⁻¹² m²s⁻¹) were determined for parabolic growth stage.

NMR study of proton dynamics in ferroelectric KIO₃*2HIO₃ crystal

Tue, 01 Jan 2008 00:00:00 GMT

NMR study of proton dynamics in ferroelectric KIO₃*2HIO₃ crystal Baisa, D.F.; Chesnokov, E.D.; Ovcharenko, A.I.; Vertegel, I.G. The temperature dependence of the proton spin-lattice relaxation time T₁ has been studied in ferroelectric KIO₃*2HIO₃ crystal. It is shown that the proton jumping along 0—H....0 contact has been shown to be the main relaxation mechanism. At temperatures exceeding the phase transition one, e>Tc, the proton relaxation is caused by the motion thereof in symmetric two-well potential of the hydrogen bond with activation energy Ec = 3.4 kcal/mol. At T

Tuning of piezoelectric parameters in the phase transition process via the transient state

Tue, 01 Jan 2008 00:00:00 GMT

Tuning of piezoelectric parameters in the phase transition process via the transient state Ishchuk, V.M.; Spiridonov, N.A. The influence of the electric field on the stability of phases in antiferroelectric substance with a small difference in energies of the ferroelectric (FE) and antiferroelectric (AFE) states is studied. It is theoretically predicted that the interaction between the coexisting domains of (FE) and (AFE) phases provides the stability of the inhomogeneous intermediate state of the substance in external electric field. The composition-electric field phase diagrams with intermediate state are obtained for the lanthanum modified lead zirconate-titanate based solid solutions. Variation of piezoelectric properties of these solid solutions during the phase transition via intermediate state is studied. The effective control of piezoelectric parameters is shown to be possible in materials with such phase transition.

The effect of impurity and intrinsic defects on the energy structure and dynamic of electronic processes CdTe:V and Cd₁₋ₓHgₓTe:V crystals

Tue, 01 Jan 2008 00:00:00 GMT

The effect of impurity and intrinsic defects on the energy structure and dynamic of electronic processes CdTe:V and Cd₁₋ₓHgₓTe:V crystals Gnatenko, Yu.P.; Bukivskij, P.M.; Piryatinski, Yu.P.; Faryna, I.O.; Furyer, M.S.; Gamernyk, R.V. The electron trapping and detrapping processes in the semi-insulating CdTe:V crystals have been studied using a new time-resolved photoelectric spectroscopy technique. It has been shown that the electron processes in such crystals involving the impurity centers and intrinsic defects are fast and occur in the nanosecond range. The information on the nature and energy structure of the anisotropic impurity centers has been obtained. Two different photogeneration mechanisms of free electrons have been revealed: the direct photoionization of electrons from the ground impurity states and their self-ionization from the excited impurity states which are in resonance with the conduction band. It was found that the photosensitivity region for Cd₁₋ₓHgₓTe:V crystals (x = 0.018) at 300 K is in the range from 0.9 to 1.7 μm.

Functional Materials, 2008, № 1

Initial stages of diffusion and phase formation in Sc/Si layered systems

NMR study of proton dynamics in ferroelectric KIO₃*2HIO₃ crystal

Tuning of piezoelectric parameters in the phase transition process via the transient state

The effect of impurity and intrinsic defects on the energy structure and dynamic of electronic processes CdTe:V and Cd₁₋ₓHgₓTe:V crystals