EPR of the Gd³⁺ probe near ferroelectric phase transition in Pb₅Ge₃O₁₁

Abstract

The EPR spectra of Pb₅Ge₃O₁₁ : Gd³⁺ have been studied in the temperature range 300–520 K. Anomalous EPR line width broadening and line splitting has been observed on going through the ferroelectric phase transition. The temperature dependencies of the EPR line width and the line splitting are used to estimate the extension of the critical interval where thermodynamic anomalies are expected to be driven by fluctuations. The temperature behaviour of the local order parameter and its fluctuations is analyzed.

Keywords:

• Critical phenomena
• Ferroelectric phase transition
• Electron paramagnetic resonance
• Lead germanate