High dielectric permittivity and suppressed loss in ErxEu1-xMnO3-δ ceramics through two-phase coexistence and defect chemistry

In this work, Er x Eu 1−x MnO 3−δ (x = 0, 0.2, 0.5, 0.8, 1.0) ceramics were synthesized via conventional solid-state reaction, and the synergistic effects of phase coexistence and defect chemistry on dielectric properties were investigated. Multiple experimental validations confirm composition-dependent structural evolution from orthorhombic to hexagonal phases, with stable two-phase coexistence occurring at x = 0.5. X-ray photoelectron spectroscopy reveals that this optimal composition possesses the maximum Mn 2+ fraction (35.19%) and oxygen vacancy concentration. The x = 0.5 sample exhibits an ultrahigh dielectric permittivity (ε′ ≈ 3.5 × 10 4 at 1 kHz, 300 K) and a low loss tangent (tanδ ≈ 0.03). Impedance spectroscopy and conductivity analysis verify that phase boundaries and associated defect clusters promote interfacial polarization while impeding long-range charge migration. This study demonstrates that the synergy of controlled two-phase coexistence and defect engineering is a valid strategy for achieving high-performance rare-earth manganite dielectrics.