Effect of sintering temperature on the dielectric and impedance properties of rare-earth manganese ErMnO3

Abstract

Polycrystalline ErMnO₃ ceramics were synthesized through a solid-state reaction method and systematically characterized to investigate the influence of sintering temperature (ranging from 1300 to 1450 ℃) on their structural, microstructural, and electrical properties. X-ray diffraction analysis confirmed the formation of a single hexagonal perovskite phase (space group P6₃cm) at temperatures above 1350 ℃. Scanning electron microscopy observations indicated improved densification and progressive grain growth with increasing sintering temperature; however, abnormal grain overgrowth was observed at 1450 ℃. X-ray photoelectron spectroscopy revealed that Er³⁺ is the predominant oxidation state, while higher sintering temperatures facilitated the generation of oxygen vacancies, leading to the partial reduction of Mn³⁺ to Mn²⁺. Dielectric measurements showed that the sample sintered at 1400 ℃ exhibited the highest permittivity (ε′ = 1.532 × 10⁵ at 1 kHz and 300 K) and the lowest dielectric loss (tanδ = 2.270 at 1 kHz and 300 K), indicating optimal polarization behavior. Impedance spectroscopy further demonstrated that this sample had the lowest equivalent resistance, suggesting enhanced charge carrier mobility. Reduced electric modulus values in the mid- to high-frequency range supported the conclusion that structural defects were effectively suppressed. These findings highlight the critical role of sintering temperature in determining the electrical performance of ErMnO₃ ceramics, with 1400 ℃ yielding the most favorable combination of structural stability, defect minimization, and improved dielectric response, thereby enhancing its potential for application in multifunctional electronic devices.