Dielectric Measurements as a Function of Temperature of Sodium‐Lithium Phosphate Glasses Evaluated at 10 MHz and 9 GHz

Abstract

Dielectric constant measurements can be performed at temperatures greater than room temperature; some techniques are shown in this work. The dielectric constant of phosphate glasses, measured in the X‐band microwave range, was determined using a microwave setup assembled to measure the shift in the standing wave pattern produced by the insertion of the sample inside the waveguide. The glass system 50P2O5 · 25Li2O · 25Na2O was chosen in this work due to its lower melting point and lower transition temperature (Tg) values. The dielectric constant of the glass studied in this work increases in the temperature range 25–330°C, as shown by the results at radio and microwave frequencies. The method of standing wave shift was applied, and it is shown to be a useful tool to estimate the Tg of glasses. This assumption was confirmed by differential thermal analysis technique. Measurements were compared to that at 10 MHz by impedancimetric methods.