The effect of ionising radiation on the photoluminescence and radioluminescence properties of nanoparticle and bulk NaMgF3:Ce,Sm

Abstract Photoluminescence (PL) and radioluminescence (RL) measurements were made on both nanoparticle and bulk NaMgF3:Ce,Sm, before, during, and after X-ray irradiation. The relative concentrations of Sm3+ and Sm2+ were markedly different for the nanoparticle and bulk samples. Sm3+ dominated the PL in NaMgF3:Ce,Sm nanoparticles while the bulk sample showed Sm3+ and Sm2+ PL. Ce3+ PL and Ce3+ sensitisation of the Sm3+ PL emission was observed for nanoparticle and bulk samples. In both samples we observed the radiation-induced valence conversions Sm3+ → Sm2+ and Ce3+ → Ce4+, such that the PL intensities of each valence could be used to monitor radiation doses. A more intense PL from oxygen-related point defects was found in nanoparticles that decreased with radiation dose and hence may also be used for radiation dosimetry. Sm3+, Sm2+, and Ce3+ RL was seen in the bulk sample where the RL depended on the dose and the Ce3+ RL was independent of the dose above ∼4 kGy. Only Sm3+ and Sm2+ RL was found in nanoparticles where the Sm3+ RL decreased by only 0.5%/kGy above 3 kGy. Our results show that nanoparticle and bulk NaMgF3:Ce,Sm can potentially be used as PL and RL dosimeters, where the signals from Ce3+, Sm2+, Sm3+, and the oxygen-related defect provide multiple means of measuring real-time and cumulative doses that may be useful for radiotherapy quality assurance.