Colossal and relaxor-like dielectric behaviors in SrCrO4 ceramics

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).