Luminescent properties of Cr-doped (GdX, Y1−X)3Al5O12 infra-red scintillator crystals

• Cr-doped (GdX Y1−X)3Al5O12 crystals were grown by a micro-pulling down method.
• Their crystal structures were examined by powder X-ray diffraction measurements.
• X-ray-excited scintillation peaks of these crystals were observed around 700 nm.
• No peak shift of Cr3+ luminescence was observed in this system.
• The two crystals (X = 0 and 0.25) were transparent in the visible-IR region.

Cr-doped (GdX Y1−X)3Al5O12 (X = 0, 0.25, 0.50) crystals prepared by the micro-pulling down method were investigated to develop a infra-red scintillator for implantable patient dosimeter in radiation therapy. In order to evaluate their optical and scintillation performance, the following properties were measured: (i) transmittance between ultra-violet and near-infra red region, (ii) photoluminescence spectra under Xe-lamp excitation, and (iii) X-ray excited radio-luminescence spectra. Cr:Y3Al5O12 and Cr:(Gd0.25 Y0.75)3Al5O12 crystals showed increased transmittance of 80%, while Cr:(Gd0.50 Y0.50)3Al5O12 had a lower transmittance of 40% due to its polycrystalline structure. In addition, all the Cr:(GdX Y1−X)3Al5O12 crystals showed sharp scintillation luminescence peaks ascribed to Cr3+ d–d transitions. Therefore, these results suggested that Cr:Y3Al5O12 and Cr:(Gd0.25 Y0.75)3Al5O12 crystals can be candidate materials for the dosimeter use.