Colossal and relaxor-like dielectric behaviors in SrCrO4 ceramics

Highlights: • Three sets of relaxations (R1, R2, and R3) were observed in SrCrO4. • The relaxation R1 is caused by defect dipole -Cr³⁺ due to humidity. • The relaxation R2 is a Maxwell-Wagner relaxation created by grain boundaries. • The relaxation R3 results from the hopping motion of oxygen vacancies. Ceramic SrCrO₄ samples were prepared via conventional solid state reaction route. Dielectric properties of SrCrO₄ were systematically investigated in the frequency range of 10²–10⁶ Hz and temperature range of 5–900 K. Colossal dielectric behavior near room temperature and relaxor-like dielectric behavior around 730 K with an extremely high dielectric constant up to 1.62 × 10⁵ were found. Dual relaxation mechanism composed of a dipolar and a Maxwell-Wagner relaxations is found to be responsible for the colossal dielectric behavior. The dipolar relaxation (R1) is related the defect dipole pair of -Cr³⁺ caused by chemically absorbed water. The Maxwell-Wagner relaxation (R2) results from grain boundaries. The relaxor-like dielectric behavior is associated with the hopping motion of oxygen vacancies which leads to a high-temperature relaxation (R3).