Local Dielectric Measurements of BaTiO3-CoFe2O4 Nano-composites Through Microwave Microscopy

TL;DR

This study uses microwave microscopy to measure dielectric properties of BaTiO3-CoFe2O4 nano-composites, revealing uniform dielectric behavior and insights into temperature-dependent phase transitions.

Contribution

First detailed microwave microscopy analysis of BTO-CFO nano-composites, showing uniform dielectric properties and temperature effects on Curie point shifts.

Findings

Nano-composites have a dielectric constant of ~140 at 3.8 GHz.

The Curie temperature shift in BTO-CFO is less pronounced than in pure BTO.

BTO retains good ferroelectric properties within the composite.

Abstract

We report on linear and non-linear dielectric property measurements of BaTiO3 - CoFe2O4 (BTO-CFO) ferroelectro-magnetic nano-composites and pure BaTiO3 and CoFe2O4 samples with Scanning Near Field Microwave Microscopy. The permittivity scanning image with spatial resolution on the micro-meter scale shows that the nano-composites have very uniform quality with an effective dielectric constant \epsilon_r = 140 +/- 6.4 at 3.8 GHz and room temperature. The temperature dependence of dielectric permittivity shows that the Curie temperature of pure BTO was shifted by the clamping effect of the MgO substrate, whereas the Curie temperature shift of the BTO ferroelectric phase in BTO-CFO composites is less pronounced, and if it exists at all, would be mainly caused by the CFO. Non-linear dielectric measurements of BTO-CFO show good ferroelectric properties from BTO.