Influence of CuO, MnO2, NiO, Bi2O3, and Fe2O3 modifiers on the crystalline structure and electrophysical properties of (Na,Li)NbO3 solid solutions

Abstract

Solid solutions were obtained on the basis of (Na,Li)NbO3 binary system, modified by addition of minor amount (not greater than 5 wt%) of various elements’ monoxides, including their combinations. This study focuses on the peculiar features of their crystalline structure, grain structure, and thermal-frequency behavior of relative permittivity. The modifications by simple Mn and Cu oxides demonstrate a retention of crystalline structure of initial solid solution. Addition of NiO leads to transformation of phase state, which is stipulated by high stereochemistry activity and emission ability of Ni(II). A noticeable variation of phase state occurs also due to the combined modification by the above-mentioned oxides and Bi2O3+Fe2O3 ones. It is established that high-temperature anomalies of dielectric properties are related to partial reduction of niobium. It was also shown that the given modified lead-free solid solutions are characterized with improved piezoelectric, ferroelastic, and mechanical properties, and they can be applied in the field of microwave engineering.