scholarly journals A Review on X-ray Excited Emission Decay Dynamics in Inorganic Scintillator Materials

Photonics ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 71
Author(s):  
Vineet Kumar ◽  
Zhiping Luo
Keyword(s):  
Rare Earth ◽  
Transition Metal Oxides ◽  
Radiation Detection ◽  
High Energy ◽  
Inorganic Materials ◽  
Decay Kinetics ◽  
Excitation Process ◽  
X Ray ◽  
Decay Component ◽  
Rare Earth Halides

Scintillator materials convert high-energy radiation into photons in the ultraviolet to visible light region for radiation detection. In this review, advances in X-ray emission dynamics of inorganic scintillators are presented, including inorganic halides (alkali-metal halides, alkaline-earth halides, rare-earth halides, oxy-halides, rare-earth oxyorthosilicates, halide perovskites), oxides (binary oxides, complex oxides, post-transition metal oxides), sulfides, rare-earth doped scintillators, and organic-inorganic hybrid scintillators. The origin of scintillation is strongly correlated to the host material and dopants. Current models are presented describing the scintillation decay lifetime of inorganic materials, with the emphasis on the short-lived scintillation decay component. The whole charge generation and the de-excitation process are analyzed in general, and an essential role of the decay kinetics is the de-excitation process. We highlighted three decay mechanisms in cross luminescence emission, exitonic emission, and dopant-activated emission, respectively. Factors regulating the origin of different luminescence centers controlling the decay process are discussed.

scholarly journals Rare-Earth Oxides as Alternative High-Energy Photon Protective Fillers in HDPE Composites: Theoretical Aspects

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1930
Author(s):  
Kiadtisak Saenboonruang ◽  
Worawat Poltabtim ◽  
Arkarapol Thumwong ◽  
Theerasarn Pianpanit ◽  
Chanis Rattanapongs
Keyword(s):  
Rare Earth ◽  
Attenuation Coefficient ◽  
Rare Earth Oxide ◽  
High Energy ◽  
Rare Earth Oxides ◽  
Lead Free ◽  
High Energy Photon ◽  
Energy Photon ◽  
X Ray ◽  
Shielding Properties

This work theoretically determined the high-energy photon shielding properties of high-density polyethylene (HDPE) composites containing rare-earth oxides, namely samarium oxide (Sm2O3), europium oxide (Eu2O3), and gadolinium oxide (Gd2O3), for potential use as lead-free X-ray-shielding and gamma-shielding materials using the XCOM software package. The considered properties were the mass attenuation coefficient (µm), linear attenuation coefficient (µ), half value layer (HVL), and lead equivalence (Pbeq) that were investigated at varying photon energies (0.001–5 MeV) and filler contents (0–60 wt.%). The results were in good agreement (less than 2% differences) with other available programs (Phy-X/PSD) and Monte Carlo particle transport simulation code, namely PHITS, which showed that the overall high-energy photon shielding abilities of the composites considerably increased with increasing rare-earth oxide contents but reduced with increasing photon energies. In particular, the Gd2O3/HDPE composites had the highest µm values at photon energies of 0.1, 0.5, and 5 MeV, due to having the highest atomic number (Z). Furthermore, the Pbeq determination of the composites within the X-ray energy ranges indicated that the 10 mm thick samples with filler contents of 40 wt.% and 50 wt.% had Pbeq values greater than the minimum requirements for shielding materials used in general diagnostic X-ray rooms and computerized tomography rooms, which required Pbeq values of at least 1.0 and 1.5 mmPb, respectively. In addition, the comparisons of µm, µ, and HVL among the rare-earth oxide/HDPE composites investigated in this work and other lead-free X-ray shielding composites revealed that the materials developed in this work exhibited comparable X-ray shielding properties in comparison with that of the latter, implying great potential to be used as effective X-ray shielding materials in actual applications.

CHARGE AND ORBITAL ORDER IN THE ELECTRON DOPED MAGNANITE (Bi,Ca)MnO3

2002 ◽  
Vol 16 (11n12) ◽  
pp. 1661-1666 ◽  
Author(s):  
P. D. HATTON ◽  
S. B. WILKINS ◽  
P. D. SPENCER ◽  
D. MANNIX ◽  
S. D. BROWN ◽  
...  
Keyword(s):  
Transition Metal Oxides ◽  
High Energy ◽  
Charge Ordering ◽  
Orbital Ordering ◽  
Orbital Order ◽  
X Ray ◽  
X Ray Scattering ◽  
Jahn Teller ◽  
Structural Modulation ◽  
Ray Scattering

The interplay between charge, spin and orbital degrees of freedom in transition metal oxides has been a matter of much interest in recent years. In this paper we present X-ray scattering results of charge and orbital ordering in the electron doped manganite Bi 0.24 Ca 0.76 MnO 3. Using High Energy X-ray Scattering (HEXS) the charge ordering, structural modulation due to the Jahn–Teller ordering and the harmonic of the structural modulation have been measured. The superlattice reflections due to the Jahn–Teller ordering are found to maximise in intensity at the Neél point. We have confirmed using resonant X-ray scattering at the K-edge of manganese and the Anisotropic Tensor of Susceptibility technique (ATS) that superlattice reflections occurring at a modulation wavevector of (0.5, 0, 0) are due to charge ordering in a Mn 3+/ Mn 4+ ordering pattern. In addition superlattice reflections corresponding to the orbital order were measured at a modulation wavevector of (0.25, 0, 0). The temperature dependence of both the Jahn–Teller structural distortion peak (1.75, 2, 0) and the charge ordering peak (3 0 0) were observed to behave identically, gradually increasing with decreasing temperature.

scholarly journals Synthesis, Structural and Optical Characterization of Titanium Dioxide Doped by (Ce, Yb) Dedicated to Photonic Conversion

2019 ◽  
Vol 20 (1) ◽  
pp. 175
Author(s):  
Zobair El Afia ◽  
Mohamed Youssef Messous ◽  
Mohamed Cherkaoui ◽  
Mounia Tahri
Keyword(s):  
Rare Earth ◽  
Inductively Coupled Plasma ◽  
High Energy ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Visible Absorption ◽  
X Ray ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry ◽  
Co Precipitation

The synthesis of TiO2 co-doped by (Ce, Yb) rare earth couple has been realized. This couple of rare earth can convert a high-energy photon to two low energy photons to enhance the energy efficiency of silicon solar cells. The undoped, 2% Ce doped- and (2% Ce, 4% Yb) Codoped- Titanium oxide were prepared by the co-precipitation method. The Infrared spectroscopy FTIR-ATR analysis indicates a continuous visible absorption in the 750–400 cm–1 region, confirming the formation of a titanium-oxygen bond. The X-Ray Diffraction characterization showed the dominance of the rutile crystalline phase with the presence of anatase one and the calculated crystallite size is between 7 to 13 nm. The X-Ray Fluorescence confirms the insertion of the dopants while the Inductively Coupled Plasma Mass Spectrometry ICP-MS showed the ratio 2 between Ce and Yb concentration. The thermogravimetric analysis indicated that Ce/Yb doped titanium was thermally stable. The absorption in the UV-visible (200 and 1000 nm) has been improved proportionally with the dopants.

The in-Situ Observation of Organic Thin Films During Growth Process by Using Grazing Incidence X-Ray Diffraction and Fluorescence Methods

1995 ◽  
Vol 39 ◽  
pp. 653-658 ◽  
Author(s):  
Kouichi Hayashi ◽  
Toshihisa Horiuchi ◽  
Kazumi Matsushige
Keyword(s):  
Thin Films ◽  
Growth Process ◽  
Organic Thin Films ◽  
High Energy ◽  
Inorganic Materials ◽  
Measuring System ◽  
In Situ Observation ◽  
X Rays ◽  
X Ray ◽  
Molecular Arrangement

Today, many researchers investigate extensively the molecular arrangement techniques for various organic materials at a nano meter scale in order to fabricate the organic thin films with novel electronic and photonic functions. For achieving this purpose, it is most important to understand the mechanism of molecular orientation during a film growth process. Thus, it have been strongly desired to develop the measuring system, which enables us to evaluate the crystal structures and molecular orientations of organic ultra thin films during the growth process. For inorganic materials, structural observations of the films grown by a molecular beam epitaxy (MBE) technique are generally conducted by using a reflection high energy electron diffraction (RHEED) method. But, this method can not be applying for many organic thin films because an electron beam destroy them. Since the organic molecules are stable to the x-rays, x-ray fluorescent and diffraction methods are suitable for such investigations of organic thin films.

scholarly journals Study of the Catalytic Strengthening of a Vacuum Carburized Layer on Alloy Steel by Rare Earth Pre-Implantation

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3420 ◽  
Author(s):  
Li ◽  
Li ◽  
Xing ◽  
Wang ◽  
Huang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Diffusion Coefficient ◽  
Rare Earth ◽  
Ion Implantation ◽  
Alloy Steel ◽  
Carbon Diffusion ◽  
High Energy ◽  
Rare Earth Ion ◽  
X Ray ◽  
Carburized Layer

Conventional carburizing has disadvantages, such as high energy consumption, large deformation of parts, and an imperfect structure of the carburizing layer. Hence, a rare earth ion pre-implantation method was used to catalyze and strengthen the carburized layer of 20Cr2Ni4A alloy steel. In this study, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive microanalysis (EDS), transmission electron microscopy (TEM), and Rockwell/Vickers hardness testing were used to analyze the microstructure, phase composition, retained austenite content, hardness, carburized layer thickness, and carbon diffusion. The results showed that lanthanum and yttrium ions implanted into the 20Cr2Ni4A steel formed solid solutions of rare earth ions and a large number of dislocations, which improved the diffusion coefficient of carbon elements on the carburized surface and the uniformity of the carbon distribution. Simultaneously, rare earth ion implantation improved the structure and hardness of the vacuum carburized layer. Compared to the lanthanum ion implantation, yttrium ion implantation caused the structure of the carburized layer to be finer, and the carbon diffusion coefficient increased by 1.17 times; in addition, the surface hardness of the carburized layer was 61.8 HRC.

scholarly journals X-Ray Photoelectron Spectroscopy of Rare Earth Halides

1986 ◽  
Vol 59 (7) ◽  
pp. 2263-2267 ◽  
Author(s):  
Yoshinori Uwamino ◽  
Akira Tsuge ◽  
Toshio Ishizuka ◽  
Hideo Yamatera
Keyword(s):  
Rare Earth ◽  
Photoelectron Spectroscopy ◽  
X Ray ◽  
Rare Earth Halides

Growth by molecular beam epitaxy of (rare-earth group V element)/III-V semiconductor heterostructures

1995 ◽  
Vol 10 (8) ◽  
pp. 1942-1952 ◽  
Author(s):  
A. Guivarc'h ◽  
A. Le Corre ◽  
P. Auvray ◽  
B. Guenais ◽  
J. Caulet ◽  
...  
Keyword(s):  
Rare Earth ◽  
Molecular Beam Epitaxy ◽  
Photoelectron Spectroscopy ◽  
Molecular Beam ◽  
High Energy ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
Group V ◽  
X Ray ◽  
Transmission Electron

This paper deals with the growth by molecular beam epitaxy of semimetallic (rare-earth group V element) compounds on III-V semiconductors. Results are presented, first on the Er-Ga-As and Er-Ga-Sb ternary phase diagrams, second on the lattice-mismatched ErAs/GaAs (δa ≈ +1.6%), YbAs/GaAs (δa/a = +0.8%), and ErSb/GaSb (δa/a ≈ +0.2%) heterostructures, and third on the lattice-matched Sc0.3Er0.7As/GaAs and Sc0.2Yb0.8As/GaAs systems (δa/a < 0.05%). Finally the growth of YbSb2 on GaSb(001) is reported. The studies made in situ by reflection high-energy electron diffraction (RHEED) and x-ray photoelectron diffraction and ex situ by x-ray diffraction, transmission electron microscopy, He+ Rutherford backscattering, and photoelectron spectroscopy are presented. We discuss the atomic registry of the epitaxial layers with respect to the substrates, the appearance of a mosaic effect in lattice-mismatched structures, and the optical and electrical properties of the semimetallic films. The problems encountered for III-V overgrowth on these compounds (lack of wetting and symmetry-related defects) are commented on, and we underline the interest of compounds as YbSb2 which avoid the appearance of inversion defects in the GaSb overlayers.

Scintillation materials based on metal iodates by rare earth doping modifications for use in radioluminescence and X-ray imaging

CrystEngComm ◽  
2021 ◽  
Author(s):  
Weiwei Xu ◽  
Hui Xu ◽  
Shuai-Hua Wang ◽  
Zhilin Wang ◽  
Xieming Xu ◽  
...  
Keyword(s):  
Rare Earth ◽  
Radiation Detection ◽  
Rare Earth Doping ◽  
X Ray ◽  
X Ray Imaging ◽  
Inorganic Scintillators

Scintillators, which can emit visible photons under γ- or X-ray excitation, are widely used in radiation detection. Traditional inorganic scintillators usually bring with some drawbacks, such as hygroscopicity or a...

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