A correlation between depolarization temperature, ergodicity and piezoelectric response in Nb5+-substituted (Na0.41K0.09Bi0.50)TiO3

A correlation between depolarization temperature, ergodicity and piezoelectricity of niobium-substituted (Na0.41K0.09Bi0.50)TiO3 has been investigated. The dielectric measurements display significant lowering of depolarization temperature and critical transition temperatures with increasing niobium content. The reduction in these characteristic temperatures has been attributed to disruption of long-range interaction between the oxygen octahedra with substitution of aliovalent niobium (+ 5) ion at the titanium (+ 4) sites. For compositions with niobium content less than 0.5 mol%, a reasonable increase (20-25%) in the piezoelectric coefficients has been observed. These coefficients decrease significantly for more niobium content more than 1.0 mol%. The results have been explained on the basis of dominance of donor-like behaviour of niobium ion at lower doping concentrations and emergence of ergodic relaxor phase due to lowering of depolarization temperature, for higher doping concentration. A structural phase diagram is proposed for niobium-doped (Na0.41K0.09 Bi-0.5)TiO3. Graphic abstract

Automated summary

The correlation between depolarization temperature, ergodicity, and piezoelectricity of niobium-substituted (Na0.41K0.09Bi0.50)TiO3 has been investigated. The dielectric measurements show a significant reduction in depolarization temperature and critical transition temperatures with increasing niobium content. The piezoelectric coefficients increase reasonably for compositions with niobium content less than 0.5 mol%, but decrease significantly for more niobium content than 1.0 mol%.