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A (C 6 H 5 C 2 H 4 NH 3 ) 2 PbI 4 crystal was prepared to investigate its photoluminescence (PL) and scintillation properties. Two PL emission peaks at 525 and 560 nm derived from the recombination of excitons were observed. The obtained PL decay curve was approximated from the sum of three exponential decay functions related to the excitonic luminescence. Under X-ray irradiation, the excitonic emission at 560 nm from shallow trap centers was observed, and the X-ray induced scintillation decay times were 0.8, 6.0, and 37 ns. The full energy peak was observed under 241 Am α-ray (5.5 MeV) irradiation, and the light yield was estimated to be ~2900 ph/5.5 MeV-α.

Undoped, 0.5, 1.0, and 2.0% Nd-doped Bi4Si3O12 (BSO) crystals were synthesized by the floating zone method. Regarding photoluminescence (PL) properties, all samples had emission peaks due to the 6p–6s transitions of Bi3+ ions. In addition, the Nd-doped samples had emission peaks due to the 4f–4f transitions of Nd3+ ions as well. The PL quantum yield of the 0.5, 1.0, and 2.0% Nd-doped samples in the near-infrared range were 67.9, 73.0, and 56.6%, respectively. Regarding X-ray-induced scintillation properties, all samples showed emission properties similar to PL. Afterglow levels at 20 ms after X-ray irradiation of the undoped, 0.5, 1.0, and 2.0% Nd-doped samples were 192.3, 205.9, 228.2, and 315.4 ppm, respectively. Dose rate response functions had good linearity from 0.006 to 60 Gy/h for the 1.0% Nd-doped BSO sample and from 0.03 to 60 Gy/h for the other samples.

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Yb-doped Bi4Ge3O12 (BGO) single crystals with different dopant concentrations were synthesized by the floating zone method, and the photoluminescence (PL) and scintillation properties in visible to near-infrared (NIR) wavelength ranges were evaluated. In PL and scintillation, a broad emission band was observed at 400–600 nm, which was ascribed to the electronic transitions of Bi3+. Furthermore, NIR emission bands due to Yb3+ were observed at 1000 nm. To evaluate scintillation detector properties, the relationship between emission intensity in NIR range and X-ray exposure dose rate was investigated. Among the present samples, 0.5 and 1% Yb-doped BGO showed good linearity in the dynamic range from 0.006 to 60 Gy/h.

We grew 0.1, 0.5, and 1% Tm-doped Bi 4 Ge 3 O 12 single crystals by the floating zone method. Their photoluminescence and scintillation properties were investigated in the range from visible to near-IR. Luminescence spectra and decay times consistent with the transitions of Tm 3+ were confirmed. X-ray-irradiated dose rate response properties were evaluated using the prepared samples and an InGaAs photodiode. The 1% Tm-doped sample showed the widest dynamic range (0.03-60 Gy/h) among the prepared samples.

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