X-ray-Induced Scintillation Properties of Nd-Doped Bi4Si3O12 Crystals in Visible and Near-Infrared Regions

Abstract

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.

Visible–Near Infrared Scintillation Properties of Er-Doped Bi4Si3O12 Single Crystals

“…These obtained values were due to the 6p-6s transitions of Bi 3+ ion. 24,37 In addition, the decay time constant of all the samples was lower than that of the undoped sample and decreased with increasing Er concentration. 24 This trend provided that the energy transfer from Bi 3+ ions to Er 3+ ions occurred.…”

“…24,37 In addition, the decay time constant of all the samples was lower than that of the undoped sample and decreased with increasing Er concentration. 24 This trend provided that the energy transfer from Bi 3+ ions to Er 3+ ions occurred. The energy transfer from Bi 3+ ions to Er 3+ ions would also be supported by the decrease of the PL QY due to Bi 3+ ions with increasing the Er concentration and overlapping emission wavelength of Bi 3+ ions and excitation wavelength of Er 3+ ions.…”

“…These PL QYs were derived from the emission due to Bi 3+ ions, and the PL QYs of all the samples were lower than that of undoped BSO (2.7%), which was reported in our previous research. 24 In addition, the PL QYs decreased as the Er concentration increased. On the other hand, the PL QYs of the 0.5, 1.0, 2.0, and 3.0% Er-doped samples monitored at 1400-1650 nm under the excitation wavelength at 520 nm were 46.5, 58.1, 69.6, and 52.4%, respectively.…”

“…In addition, the decrease of the decay time constants was observed according to the Er concentration, and the decay time constants of all the Er-doped samples were lower than that of undoped BSO reported by previous research. 24 Therefore, the decrease was caused by the energy transfer from Bi 3+ ions to Er 3+ ions as well as PL process.…”

“…23 Thus, many researchers including our group have conducted the investigation about the scintillation properties of non-doped or rare Earth (e.g., Ce 3+ , Nd 3+ , Dy 3+ , Sm 3+ , and Tb 3+ ) -doped BSO. [24][25][26][27] In this study, we focused on Er 3+ ion as a luminescence center. Er 3+ ion has the main emission peak at 1520 nm which is located at the lowest transmittance loss region in glass fiber.…”