HIGH-FREQUENCY ELECTROMAGNETIC PROPERTIES OF BOROSILICATE GLASSESWITH ADDITIVES OF La2O3, TiO2, ZrO2

Abstract

The results of studies of high-frequency electromagnetic properties of alkaline borosilicate glasses modified with lanthanum, titanium, and zirconium oxides concerning their structure are presented. The values of the spectral reflection and transmission coefficients are experimentally measured in the frequency range 12–18 GHz. The article presents typical spectra of the complex dielectric constant of the studied glass samples inthe range of 20 Hz–1 MHz, according to which both the real and imaginary parts decrease with increasing frequency, while the imaginary part decreases much faster. It is shown that the studied glasses can be used as a vacuum-tight dielectric base with low losses in the development of high-frequency devices operating in the microwave range. The influence of the chemical composition of the experimental glasses on the value of their dielectric permittivity in the frequency ranges of 20 Hz –1 MHz and 12–18 GHzis established. The structure of the studied glasses was studied by Raman spectroscopy. The influence of lanthanum, titanium, and zirconium oxides on the degree of polymerization of the structural framework was revealed. The presence of La2O3in sodium borosilicate glass causes a decrease in the polymeriza-tion of the borosilicon-oxygen framework of glass in the entire range of introduced concentrations since La2O3is in the octahedral position and acts as a modifier in the glass structure. The intro-ductionof zirconium oxide into the composition of sodium borosilicate glass has a more significant effect on the depolymerization of the glass structure than the addition of lanthanum oxide. The most serious structural changes are observed when TiO2is introduced into the compositions of such glasses, since it acts as a glass–forming agent, forming structural motifs [TiO4], which will combine with the silicon–oxygen component, forming Si–O–Ti type bridges.