Inorganic, Organic, and Perovskite Halides with Nanotechnology for High–Light Yield X- and γ-ray Scintillators

Abstract

Trends in scintillators that are used in many applications, such as medical imaging, security, oil-logging, high energy physics and non-destructive inspections are reviewed. First, we address traditional inorganic and organic scintillators with respect of limitation in the scintillation light yields and lifetimes. The combination of high–light yield and fast response can be found in Ce 3 + , Pr 3 + and Nd 3 + lanthanide-doped scintillators while the maximum light yield conversion of 100,000 photons/MeV can be found in Eu 3 + doped SrI 2 . However, the fabrication of those lanthanide-doped scintillators is inefficient and expensive as it requires high-temperature furnaces. A self-grown single crystal using solution processes is already introduced in perovskite photovoltaic technology and it can be the key for low-cost scintillators. A novel class of materials in scintillation includes lead halide perovskites. These materials were explored decades ago due to the large X-ray absorption cross section. However, lately lead halide perovskites have become a focus of interest due to recently reported very high photoluminescence quantum yield and light yield conversion at low temperatures. In principle, 150,000–300,000 photons/MeV light yields can be proportional to the small energy bandgap of these materials, which is below 2 eV. Finally, we discuss the extraction efficiency improvements through the fabrication of the nanostructure in scintillators, which can be implemented in perovskite materials. The recent technology involving quantum dots and nanocrystals may also improve light conversion in perovskite scintillators.

Optical Characteristics of ZnCuInS/ZnS (Core/Shell) Nanocrystal Flexible Films Under X-Ray Excitation

“…In addition, ZnCuInS/ZnS does not contain any high toxicity compounds like cadmium, lead, mercury, or arsenide, making it an attractive alternative for use in several applications. For the QD/PMMA fabrication, a PMMA/MMA low viscosity solution was prepared by mixing PMMA powder with liquid MMA [15,24]. Three samples of ZnCuInS/ZnS QDs in toluene were prepared by dissolving 100 mg, 150 mg, and 250 mg in 1 mL toluene in order achieve concentrations of 100 mg/mL, 150 mg/mL, and 250 mg/mL, respectively.…”

“…QDs have attracted attention since their emission spectra and electronic properties have found application as biological labels, light emitting devices, and optoelectronic sensors [9][10][11]. In addition, QDs and other scintillating materials have been proposed as candidates for ionizing radiation detectors [12][13][14][15]. On the other hand, increased awareness of the harmful effects of toxic heavy-metal compounds that could be used in QDs has led authorities to provide relevant legislation.…”

Absolute Luminescence Efficiency of Europium-Doped Calcium Fluoride (CaF2:Eu) Single Crystals under X-ray Excitation

“…The use of single crystals as radiation converters is very common in imaging or counting applications, especially when coupled with optical sensors such as photomultipliers, which are frequently employed in radiation detectors [1,2]. Additionally, they are widely used in particle physics, homeland security, and in numerous disciplines of medical imaging, such as X-ray computed and positron emission tomography (CT and PET, respectively), radiotherapy, radiography, and mammography [3][4][5][6][7][8][9][10][11][12][13][14][15][16].…”

“…In this scope, medical imaging detectors should incorporate scintillators with optimized characteristics in terms of efficiency and imaging performance. An example is the time-of-flight (TOF) technique in PET scanners, requiring inorganic scintillators with primarily extremely short decay time, high density, and light yield (LY) [2,21]. Similar concerns arise in other fast applications such as CT, in which afterglow can cause blur in the final image [7].…”

Scintillator Crystals: Structure, Characterization and Models for Better Performances

“…The paper by Maddalena et al [12] reviews the scintillation mechanism, materials and main scintillation parameters. It focuses mainly on the organic and inorganic scintillator crystals' LY and response time.…”