Dielectric Properties of Nanocrystalline Yttrium Iron Manganites Synthesized by Sol–Gel Method

Abstract

Hexagonal yttrium manganites, YMnO₃, exhibit multiferroic behavior and doping suitable cations at the either Y-site or Mn-sites can significantly influence the structural and electrical properties. Nanocrystalline Fe³⁺-doped YMnO₃ manganites substituting at the Y-sites having the general formula Y_1-xFe_xMnO₃ with x = 0, 0.1, 0.15, 0.20, 0.25 were synthesized by sol–gel method and were sintered at 1100 °C for 1 h. X-ray diffraction (XRD) studies confirmed the hexagonal phase of the samples and various structural parameters viz. lattice constant, crystallite size, X-ray density were evaluated from the XRD data. The crystallite size of the nanocrystalite manganites ranges from 39 to 63 nm. Investigation on the dielectric properties such as dielectric constant and dielectric loss of the samples was done using an impedance analyzer. The studies showed large increase in dielectric constant and dielectric loss for higher Fe³⁺-doped manganites i.e. for x ≥ 0.20. Temperature variation of dielectric properties revealed a ferroelectric phase transitions which shift to lower temperature with the increase of Fe³⁺ ion substitution.

Keywords:

• Yttrium manganites
• sol–gel method
• X-ray diffraction
• dielectric constant

Acknowledgments

The author is thankful to Central Instrumentation Facility, NIT Manipur, for XRD measurements.