Key Engineering Materials Vol. 822

Abstract: Materials with strong susceptibility with respect to the electromagnetic field, namely, ferroelectric (FE) and ferromagnetic (FM) materials are of great interest for modern electronics. On the basis of ferroelectrics, devices such as varicades, delay lines, phase shifters, etc. are being actively developed. Ferromagnets (primarily ferrites) serve as the basis for directional couplers, circulators, valves, filters, phased antenna arrays, etc. Today, the most common method of creating functional composites, combining dielectric and magnetic properties, is the introduction of classical ferroelectrics, such as triglycine sulfate, Siegnette salt (KNaC₄H₄O₆∙4H₂O), sodium nitrite, etc. in iron-containing matrices. The relevance of this approach is due to the fact that when a ferroelectric is introduced into the FM matrix, it becomes possible to create composite multiferroic materials with two types of ordering (electric and magnetic). In this paper, we study the possibilities of creating glass-ceramic multiferroic materials based on Siegnette salt and barium titanate, introduced in the pore space of ferromagnetic glass, formed by ion exchange between alkaline glass cations and salt melt. For obtaining porous glass-ceramic materials by the method of ion exchange, potassium iron-containing silicate glasses are used in the work. 15K₂O·20Fe₂O₃·55SiO₂, mol. % (KFeSi).

Abstract: The electronic structure of lithium pyrophosphates (Li₄P₂O₇) and sodium (Na₄P₂O₇) was calculated by the density functional theory method. The calculations were performed for ordered (crystalline) and disordered (corresponding to glassy) structural states of lithium and sodium pyrophosphates. The disordering of the structure is simulated by ab initio molecular dynamics from crystal state with the same atomic basis as used for ideal crystal electronic calculations.

Abstract: Fluoroaluminate glasses of the composition 2Ва (РО₃)₂–98MgCaSrBaYAl₂F₁₄-xErF₃, where x=0, 0.1, 0.5, 1.0 mol. % have been prepared by melt quenching technique and characterized by optical absorption, emission spectra and decay curve analysis. Measured transmission spectra indicate the high practical relevance of the composition of glasses under investigation for photonics and optoelectronics products. In the region of 500–700 nm, luminescence spectra with peaks at about 522, 550, and 665 nm were obtained. The positions of the luminescence bands have been described using an erbium ion energy scheme. The concentration dependences of the absolute quantum yield values for the series of Er³⁺-doped fluoroaluminate glasses were also established. The maximum value of absolute quantum yield was found for a sample with Er³⁺ concentration 0.21∙10²⁰ сm^-3. The main reason for reducing the values of absolute quantum yield is concentration quenching.

Abstract: The composite materials Fe₂O₃-ZrO₂ with different content of zirconium oxide have been obtained by thermochemical synthesis. The process of crystallization of zirconium dioxide and the effect of the amount of zirconium dioxide on the phase transformation have been studied by DTA and microscopy. The activation energy of the crystallization process was calculated by the Kissinger method to be in average 170 KJ/mol. It is shown that an increase of the ZrO₂ content leads to an increase of temperature of crystallization.

Abstract: Multilayer ceramic capacitors (MLCC) have wide application in electronic due to its electrical characteristics: low equivalent series resistance (ESR) and high volume efficiency. One of the MLCC manufacturing problems is the choice of composition for the end pastes. The experimental results of the termination pastes composition influence on the quality high-voltage MLCC investigation are presented. The causes of the defects appearance in the termination are determined, the composition of the termination paste, which ensures the quality contact of the internal electrode with the external, is proposed.