Effect of yttrium oxide on the crystallization of glasses of the MgO–Al_2O_3–SiO_2 system, nucleated by a mix of titanium and zirconium dioxides, and the transparency of glass--crystalline materials in the superhigh-frequency spectral region

Abstract

Glass–crystalline materials of the MgO–Al2O3–SiO2 system are used for the production of items with low dielectric losses in the superhigh-frequency spectral region, high mechanical strength, and thermal stability of the dielectric properties. Some glass–crystalline materials of this system are also transparent in the visible region. This paper discusses the phase transformations that accompany the crystallization of glasses of the MgO–Al2O3–SiO2 system with an additive of yttrium oxide, nucleated by a mix of titanium and zirconium dioxides. Segregation of nanosize crystalline phases not previously recorded in this system is detected. A mechanism is proposed for the effect of yttrium oxide on the phase-separation processes. The permittivity and the tangent of the dielectric-loss angle at a frequency of 1010 Hz of the glass–crystalline materials with a mixed crystallization nucleator are compared with the phase composition of the samples.