High-temperature relaxations in CaF2 single crystals

The dielectric properties of CaF2 single crystals were investigated in the temperature range from room temperature to 773 K and the frequency range of 50 Hz-10 MHz. A Debey-like relaxation and a relaxor-like dielectric anomaly were observed. Raman spectrum and the differential scanning calorimeter measurement revealed the coexistence of native defects of fluorine vacancies (VF) and interstitial fluorine ions (F′i) and external defect of oxygen ions. Impedance analysis showed that the Debey-like relaxation results from the mobility of VF, while the relaxor-like behavior is associated with the relaxation caused by complexes of O″−VF.