Magnetic and optical properties of Co-doped PbMoO₄single crystals

Pure and doped with 0.2, 0.5 and 1 mol% Co²⁺ions PbMoO₄single crystals are grown by the Czochralski method. The electron paramagnetic resonance (EPR) and photoluminescence (PL) are investigated at 4-300 K. It is found that weak ferromagnetic interactions with Curie-Weiss temperature of 2.45 and 2.8 K are present for PbMoO₄crystals doped with 0.2 and 0.5 mol% Co²⁺ions, respectively. The magnetic phase changes from ferromagnetic to antiferromagnetic at about 10 K. Two emission bands are observed at 515 and 705 nm. The red emission is attributed to MoO₄clusters perturbed by O^2-vacancies. The temperature dependence of the 515 nm emission intensity shows anomalies at ∼50 and ∼150 K, that are suggested to arise from the trapping phenomena and thermal quenching process, respectively.