Structure and dielectric response of Na1 − x K x NO2 nanocomposite solid solutions

Abstract

This paper reports on the results of the investigation into the thermal evolution of the structure and dielectric properties of Na1 − x K x NO2 solid solutions (x = 0, 0.05, 0.10) embedded in porous glass with an average pore diameter of 70 ± 10 Å in the range 300–447 K, i.e., in the ferro-and paraelectric phases. The structural properties of the bulk and nanostructured materials are compared. It is shown that the introduction of small amounts of potassium brings about a noticeable change in the intensity ratio of the elastic Bragg peaks, while leaving the space group characterizing the structure of these nanocomposites unaffected. An increase in the potassium fraction does not result in a substantial decrease in the phase transition point. Measurements of the dielectric response have revealed that an increase in the potassium content gives rise to a marked “hardening” of the lattice in the premelting state, which reduces dielectric losses.