Formation of Zn- and Si-Based Oxide Systems: Analysis of Temperature Dependence of the Energy State

This article presents the results of the thermal analysis of dried colloidal solutions based on zinc nitrate with changes in tetraethoxysilane (TEOS) content. The main stages of the thermal decomposition of the dried sols were established and the activation energies of each stage were determined based on the results of thermogravimetric measurements using the Erofeev-Kolmogorov approach. For each stage, the products of thermal destruction in the gas phase were determined by mass-spectrometry. It was shown that the chemical decomposition in all samples started at a temperature above 200°C, and the temperature of zinc hydroxonitrate decomposition increased with increasing TEOS content in the ash, while the activation energy of that process decreased. X-ray diffraction analysis revealed that the thermal decomposition of dried sols at 600°C resulted in the formation of mixtures of ZnO in hexagonal syngony with amorphous SiO2 in amounts from 10 to 50 wt%.

The Propagation of Thermoelastic Waves in Anisotropic Media of Orthorhombic, Hexagonal, and Tetragonal Syngonies

The investigation of wave propagation in elastic medium with thermomechanical effects is bound to have important economic implications in the field of composite materials, seismology, geophysics, and so on. In this article, thermoelastic wave propagation in anisotropic mediums of orthorhombic and hexagonal syngony having heterogeneity along z-axis is studied. Such medium has second-order axis symmetry. By using analytical matriciant method, a set of equations of motions in thermoelastic medium are reduced to an equivalent set of the first-order differential equations. In the general case, for the given set of equations, structures of fundamental solutions are made and dispersion relations are obtained.

Auxeticity Properties of Hexagonal Syngony Crystals

Pointing auxeticity surfaces of Be, Zn, MoS2, MnAs, TiB2 and BeCu (2,4 atm. % Cu) single crystals of hexagonal system were plotted for the first time using the experimental values of the elastic modulus , which given in the tables Landolt-Bernstein. The criteria of appearance of axial and noaksial auxeticity were established. The influence of alloying and temperature on effects of Be abnormal deformation was detected. The mechanisms of auxeticity properties formation in hexagonal crystals were established.