AC RESPONSE OF POLYCRYSTALLINE SODIUM YTTRIUM FLUORIDE

Ac response of polycrystalline sodium yttrium fluoride (NaYF4) has bee n studied in the temperature region of 350-950 K and in the frequency range 50 Hz-100 kHz using blocking electrodes. From the admittance plo ts, the bulk conductivity (sigma), dielectric constant (epsilon') and loss angle (tan delta) were determined at different temperatures and f requencies. The conductivity was found to increase with increasing tem perature. Large value of epsilon' observed at high temperatures was at tributed to space charge polarization effects. The relaxation characte r of tan delta was observed. The ac conductivity was found to increase with increasing frequency.