24 research outputs found
Needs, trends, and advances in scintillators for radiographic imaging and tomography
Scintillators are important materials for radiographic imaging and tomography
(RadIT), when ionizing radiations are used to reveal internal structures of
materials. Since its invention by R\"ontgen, RadIT now come in many modalities
such as absorption-based X-ray radiography, phase contrast X-ray imaging,
coherent X-ray diffractive imaging, high-energy X- and ray radiography
at above 1 MeV, X-ray computed tomography (CT), proton imaging and tomography
(IT), neutron IT, positron emission tomography (PET), high-energy electron
radiography, muon tomography, etc. Spatial, temporal resolution, sensitivity,
and radiation hardness, among others, are common metrics for RadIT performance,
which are enabled by, in addition to scintillators, advances in high-luminosity
accelerators and high-power lasers, photodetectors especially CMOS pixelated
sensor arrays, and lately data science. Medical imaging, nondestructive
testing, nuclear safety and safeguards are traditional RadIT applications.
Examples of growing or emerging applications include space, additive
manufacturing, machine vision, and virtual reality or `metaverse'. Scintillator
metrics such as light yield and decay time are correlated to RadIT metrics.
More than 160 kinds of scintillators and applications are presented during the
SCINT22 conference. New trends include inorganic and organic scintillator
heterostructures, liquid phase synthesis of perovskites and m-thick films,
use of multiphysics models and data science to guide scintillator development,
structural innovations such as photonic crystals, nanoscintillators enhanced by
the Purcell effect, novel scintillator fibers, and multilayer configurations.
Opportunities exist through optimization of RadIT with reduced radiation dose,
data-driven measurements, photon/particle counting and tracking methods
supplementing time-integrated measurements, and multimodal RadIT.Comment: 45 pages, 43 Figures, SCINT22 conference overvie
Crystal Growth and Phase Formation of High-Entropy Rare-Earth Aluminum Perovskites
We demonstrate for the first time the crystal growth
of high-entropy
rare-earth (RE) aluminum perovskites (REAlO3) using the
micro-pulling-down method to inform future exploration of functional
crystals. To determine how composition affects phase formation, we
formulate equiatomic compositions containing five REs from the following
list: Lu, Yb, Tm, Er, Y, Ho, Dy, Tb, Gd, Eu, Sm, Nd, Pr, Ce, La. To
test whether combinations of REs with similar ionic radii may favor
a single phase, compositions containing REs with consecutive or nonconsecutive
ionic radius values were formulated. Powder and single-crystal X-ray
diffraction indicate that crystals containing only REs with similar
ionic radii that form orthorhombic single-RE REAlO3 are
a single phase. Crystals containing REs with dissimilar ionic radii
or mixtures of REs that form orthorhombic, rhombohedral, and tetragonal
single-RE REAlO3 are a mixture of phases. The elemental
distribution in single-phase crystals analyzed via electron probe
microanalysis confirms no evidence of preferential incorporation of
any of the constituent REs. The distribution and composition of secondary
phases were analyzed via scanning electron microscopy and energy dispersive
spectroscopy; secondary phases were seen as a small region in the
center of the crystals with branching features closer to the outer
surface
Conference Comments
The 16th International Conference on Inorganic Scintillators and their Applications (SCINT 2022) was organized by the Los Alamos National Laboratory, and held in Santa Fe, NM, USA, from September 19 to October 23, 2022. More than 200 colleagues from nearly 20 different countries finally participated in the conference. The program consisted of five invited and ten keynote lectures, and 74 oral and 46 poster contributions. A special memorial session was devoted to Prof. Richard T. Williams. Extended exhibition with altogether about ten exhibitor stands provided another link to the market applications behind the research. An intense and structured research and development in the field of scintillators was represented by 15 sessions oriented toward various material technologies including nanomaterials, metamaterials, and classical bulk single crystals and optical ceramics. Their characterization, modeling, and underlying physical mechanisms description constituted the subject of a major part of conference contributions. Finally, various applications of inorganic scintillators were presented and discussed