Photoinduced Reversible Local Deformation of the Surface Relief in Bulk Single Crystals of TlInSe2, TlGaTe2, and TlSe

Technical Physics Letters - Giant macroscopic expansion of the surface relief, localized within a laser spot size, has been observed in bulk single crystals of TlInSe2, TlGaTe2, and TlSe at room...     

Dielectric properties of MnGa2S4 single crystals in an alternating electric field

The results of studies of the frequency and temperature dependences of dielectric conductance and the tangent of the angle of dielectric losses for MnGa₂S₄ single crystals in a varying electric field are presented. Their values are determined experimentally. An increase in the dielectric conductivity is related to an increase in the defect concentration as temperature is increased. At the temperatures under study, a resonance peak is observed for ? and tanδ in the frequency range of 435–500 kHz. It is found that, in the frequency range of 25?2 × 10⁵ kHz, the tangent of the angle of dielectric losses decreases in reverse proportion to the frequency (～1/ω).     

Nano inhomogeneity effects on small Ag/n-Si Schottky diode parameters at high temperature

Schottky diodes with an Ag/n-Si/W/Cu structure and 100μm in diameter were studied.Analyzing the silver metal surface coating on the n-Si substrate using a scanning probe microscopy(SPM) device showed a large number of nano patches in the surface with dimensions of 0 to 100 nm.The potential distribution of the patches revealed that the potential of each patch with the neighboring patches was different.The electrical characteristics of the devices were studied between temperature ranges of 300 and 380 K.When the temperature ideality factor approximately increases,the potential barrier height decreases.The potential barrier height was calculated separately from theⅠ-Ⅴand C-V characteristics.The main reasons for the significant difference between room temperature and higher temperatures were the differences in patch distribution,the different potentials of each patch,and the interactions between them.The effective potential barrier height depended on the degree of inhomogeneity,and thus the operating potential barrier height in the contact surface was smaller than the average value,and the ideality factor was more than unitary.With the increase in the potential value,the ideality factor becomes close to unitary, and with increasing temperatures,the ideality factor is increased.In this case,the maximum potential barrier height accrues at a greater distance from the metal contact.For this reason,at high temperatures the average value of the potential barrier height is smaller.Moreover,with increasing temperature,the ideality factor is increased.     

Calculation of Integer and Noninteger <Emphasis Type="Italic">n</Emphasis>-Dimensional Debye Functions Using Binomial Coefficients and Incomplete Gamma Functions

Recursion and analytical relations for the evaluation of integer and noninteger n-dimensional Debye functions have been derived. Using the binomial expansion theorem, these functions are expressed through the binomial coefficients and familiar incomplete gamma functions. This simplification and the use of the memory of the computer for calculation of binomial coefficients may extend the limits to large arguments for users and result in speedier calculation, should such limits be required in practice. Comparison of numerical results shows that analytical solutions are accurate almost from the beginning of the calculation time. The series expansion relations obtained is sufficiently accurate over the entire range of parameters. The convergence rate of the series is estimated and discussed.     

On the incorrectness of the traditional proof of the prigogine principle of minimum entropy production

It is demonstrated that the traditional proof of the Prigogine principle of minimum entropy production is incorrect. Provided that the Onsager reciprocal relations are satisfied, the Prigogine principle is valid when and only when generalized thermodynamic fluxes are simultaneously equal to zero at nonzero values of the generalized thermodynamic forces.     

System PbTe–CoSe2

Phase relations in the PbTe–CoSe₂ system were studied by physicochemical analysis. The system was found to contain an incongruently melting compound of composition PbCoSe₂Te. The lattice parameters, microhardness, and standard thermodynamic functions of PbCoSe₂Te were determined. At room temperature, the solubility of CoSe₂ in PbTe is 10 mol % and that of PbTe in CoSe₂ is 8 mol %.     

Dynamics of luminescence bursts during the dry friction of quartz and PMMA

The dynamics of distribution of the triboluminescence (TL) burst intensity during the dry friction of crystalline quartz and amorphous poly(methyl methacrylate) (PMMA) plates on a rotating steel shaft have been studied. The TL bursts arise as a result of the chemical bond rupture on the banks of friction-induced cracks with linear dimensions on the order of several millimeters. For crystalline quartz, the TL burst intensity distribution displays two maxima for the signal intensities differing by a factor of ≈4. During friction, the numbers of bursts in these maxima vary in the opposite directions. For PMMA, the distribution does not exhibit clearly pronounced maxima, but it still reveals two ensembles of TL bursts with the intensities differing by a factor of ≈6, in which the numbers of bursts also varied in the opposite directions. It is concluded that the dry friction of quarts and PMMA leads to the development of two ensembles of wear cracks, the linear dimensions of which differ by a factor of 2–3.     

Solution of Certain Problems in the Thermal Diffusion of Binary Gases

Two variants of the experimental method of unique determination of the thermal-diffusion ratio (K _t) of binary gases are described. A formula expressing the temperature and concentration dependence of K _t and obtained by a thermodynamic method is proposed.     

Acoustophotovoltaic effect in TlInSe2, TlInTe2, and TlGaTe2 single crystals

Procedures have been developed for growing TlInSe₂, TlInTe₂, and TlGaTe₂ single crystals. Float zoning has been shown to be the most effective process for the crystal growth of these compounds. The grown single crystals exhibit a sizeable acoustophotovoltaic effect.     

Numerical simulation of the crystallization front inversion in oxide single crystals grown from melt using the Czochralski method

The process of pulling a Czochralski grown oxide single crystal out from melt has been numerically simulated for the first time from the moment of seeding until attaining a stationary growth regime. It is established that the phase boundary inversion at the lateral (shouldering) growth stage is a rather complicated process accompanied by intense oscillations of the crystallization rate. Diagrams illustrating variations of the crystal shape during this process are presented.