Giant and negative dielectric tunability induced by interfacial polarization in Pb(Fe1/2Nb1/2)1-xTixO3 single crystals

TL;DR

This paper reports giant and negative dielectric tunability in Pb(Fe1/2Nb1/2)1-xTixO3 single crystals, driven by interfacial polarization, with significant tunability at low fields and frequencies, expanding understanding of ferroelectric materials.

Contribution

It reveals the mechanisms behind giant and negative dielectric tunability in Pb(Fe1/2Nb1/2)1-xTixO3, emphasizing the role of interfacial polarization and models explaining these phenomena.

Findings

Capacitance reduction >80% at low fields and frequencies

Negative tunability observed only in tetragonal samples

Interfacial polarization as the key mechanism

Abstract

The giant and negative dielectric tunability of Pb(Fe1/2Nb1/2)1-xTixO3 single crystals is reported. A low field of 120 V/cm can induce a great reduction of the capacitance, and the tunability is larger than 80% in low frequency range (<1 MHz) at room temperature. This giant tunability is ascribed to the interfacial polarization at the interface of electrode/sample. A negative dielectric tunability detected only in the tetragonal sample can be also attributed to the interfacial polarization. The origin of the giant and negative tunabilities is discussed with the multipolarization-mechanism model and equivalent circuit model, respectively.