scholarly journals Samarium doped alkaline earth halides as red-emitting scintillators and phosphors

2021 ◽  
Author(s):  
◽  
Laura Catherine Dixie
Keyword(s):  
Single Crystals ◽  
Decay Time ◽  
Alkaline Earth ◽  
Radiation Detection ◽  
Red Emission ◽  
X Ray ◽  
Decay Times ◽  
Integrated Intensity ◽  
Imaging Resolution ◽  
Alkaline Earth Halides

<p>This thesis is concerned with the manufacture, spectroscopic characterisation, and radiation detection performance of three rare earth doped alkaline earth halides; these were designed for scintillation or phosphor detection of x-rays and γ-rays. The materials are transparent polycrystals of lanthanum or praseodymium stabilised cubic barium chloride ((La,Pr)₀.₁₂₅Ba₀.₈₇₅Cl₂.₁₂₅), BaCl₂ - SrCl₂ solid solutions, or single crystals of CaF₂. The primary dopant investigated was Sm²⁺ since this has a red emission in all the materials which is well matched to the spectral sensitivity of silicon photodiodes. The cubic structure of the polycrystalline materials is essential for optical transparency, and so the structural stability of the materials has been investigated using x ray diffraction and thermal analysis. For CaF₂ large single crystals were unintentionally produced without following the usual Bridgman-Stockbarger or Czochralski methods. All of the materials showed predominantly Sm²⁺ ions, and only in CaF₂ could evidence of Sm³⁺ ions also be seen.  The spectroscopy of the 4f⁵5d¹ → 4f⁶ red emission, including lifetimes, and absorption of Sm²⁺ ions in all these materials is reported; a strong thermal cross over to 4f⁶ → 4f⁶ emission is observed and successfully modelled. A time correlated single photon counted system has been built to measure the scintillation decay time of these materials. The system yields decay times in excellent agreement with the literature values. The performance of the materials as scintillators is limited to varying degrees by the formation of colour centres which slow the electron-hole recombination process after x-irradiation. Ba₀.₃Sr₀.₇Cl₂:Sm was found to be a bright and fast x-ray phosphor. The integrated intensity (per x-ray half thickness of material) of the radioluminescence is ~ 30 % that of the commercial material, the scintillation lifetime is ~ 30 μs (c.f. milliseconds for Gd₂O₂S:Tb³⁺) and the imaging resolution is 6 LP/mm (c.f. 4.2 LP/mm for Gd₂O₂S:Tb³⁺). CaF₂:Sm²⁺ was shown to be a red-emitting scintillator with a decay time of ≤ 1 μs and a light output of 15,000 photons/MeV when cooled by dry ice. The x-ray imaging resolution was high at 8.5 LP/mm. Several of the materials have been tested for performance as neutron detecting phosphors by adding neutron capture elements such as gadolinium or lithium, the strongest emission observed was 6 % the integrated intensity of the standard material ⁶LiI(Eu²⁺).</p>

scholarly journals Samarium doped alkaline earth halides as red-emitting scintillators and phosphors

2021 ◽  
Author(s):  
◽  
Laura Catherine Dixie
Keyword(s):  
Single Crystals ◽  
Decay Time ◽  
Alkaline Earth ◽  
Radiation Detection ◽  
Red Emission ◽  
X Ray ◽  
Decay Times ◽  
Integrated Intensity ◽  
Imaging Resolution ◽  
Alkaline Earth Halides

<p>This thesis is concerned with the manufacture, spectroscopic characterisation, and radiation detection performance of three rare earth doped alkaline earth halides; these were designed for scintillation or phosphor detection of x-rays and γ-rays. The materials are transparent polycrystals of lanthanum or praseodymium stabilised cubic barium chloride ((La,Pr)₀.₁₂₅Ba₀.₈₇₅Cl₂.₁₂₅), BaCl₂ - SrCl₂ solid solutions, or single crystals of CaF₂. The primary dopant investigated was Sm²⁺ since this has a red emission in all the materials which is well matched to the spectral sensitivity of silicon photodiodes. The cubic structure of the polycrystalline materials is essential for optical transparency, and so the structural stability of the materials has been investigated using x ray diffraction and thermal analysis. For CaF₂ large single crystals were unintentionally produced without following the usual Bridgman-Stockbarger or Czochralski methods. All of the materials showed predominantly Sm²⁺ ions, and only in CaF₂ could evidence of Sm³⁺ ions also be seen.  The spectroscopy of the 4f⁵5d¹ → 4f⁶ red emission, including lifetimes, and absorption of Sm²⁺ ions in all these materials is reported; a strong thermal cross over to 4f⁶ → 4f⁶ emission is observed and successfully modelled. A time correlated single photon counted system has been built to measure the scintillation decay time of these materials. The system yields decay times in excellent agreement with the literature values. The performance of the materials as scintillators is limited to varying degrees by the formation of colour centres which slow the electron-hole recombination process after x-irradiation. Ba₀.₃Sr₀.₇Cl₂:Sm was found to be a bright and fast x-ray phosphor. The integrated intensity (per x-ray half thickness of material) of the radioluminescence is ~ 30 % that of the commercial material, the scintillation lifetime is ~ 30 μs (c.f. milliseconds for Gd₂O₂S:Tb³⁺) and the imaging resolution is 6 LP/mm (c.f. 4.2 LP/mm for Gd₂O₂S:Tb³⁺). CaF₂:Sm²⁺ was shown to be a red-emitting scintillator with a decay time of ≤ 1 μs and a light output of 15,000 photons/MeV when cooled by dry ice. The x-ray imaging resolution was high at 8.5 LP/mm. Several of the materials have been tested for performance as neutron detecting phosphors by adding neutron capture elements such as gadolinium or lithium, the strongest emission observed was 6 % the integrated intensity of the standard material ⁶LiI(Eu²⁺).</p>

Über das Erdalkalimetall-Lanthanoid-Kupfer-Oxomolybdat (Cu0,22Mg0 ,78)BaNd2Mo4O16/The Alkaline Earth Rare Earth Copper-Oxomolybdate (Cu0.22Mg0.78)BaNd2Mo4O16

1995 ◽  
Vol 50 (4) ◽  
pp. 577-580 ◽  
Author(s):  
H. Szillat ◽  
Hk. Müller-Buschbaum
Keyword(s):  
Crystal Structure ◽  
Rare Earth ◽  
Single Crystals ◽  
Alkaline Earth ◽  
Three Dimensional ◽  
Space Group ◽  
X Ray ◽  
Ray Methods

Single crystals of (Cu0.22Mg0.78)BaNd2Mo4O16 have been prepared by crystallization from melts and investigated by X-ray methods. The compound crystallizes monoclinically, space group C62h - C12/c1, Z = 4, a = 5.351(1), b = 12.891(2), c = 19.391(4) Å,β = 90.899(14)° and is isotypic to CuKHo2Mo4O16. The crystal structure is dominated by BaO10 and NdO8 polyhedra forming a three-dimensional polyhedra network, which is filled by axially distorted (Cu,Mg)O6 octahedra and MoO4 tetrahedra.

scholarly journals Synthese und Kristallstruktur eines Alkali-Erdalkali-Kupfer-Halogeno-Oxovanadats: KBaCuV2O7Cl / Synthesis and Crystal Structure of an Alkaline Alkaline-Earth Halide Oxide of Copper and Vanadium: KBaCuV2O7Cl

1994 ◽  
Vol 49 (3) ◽  
pp. 355-359 ◽  
Author(s):  
F.-D. Martin ◽  
H. Müller-Buschbaum
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Alkaline Earth ◽  
Copper Ion ◽  
Tetragonal Symmetry ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
X Ray ◽  
Symmetry Space ◽  
Symmetry Space Group

Abstract Single crystals of KBaCuV2O7Cl have been prepared by a flux technique and investigated by X-ray analysis. The compound crystallizes with tetragonal symmetry, space group C24v-P4 bm, a = 8.8581, c = 5.4711 Å, Z = 2. The crystal structure shows Cu2+ within a one sided strongly distorted CuO4Cl2 octahedron. The copper ion is shifted towards the nearer Cl- neighbour to form a CuO4Cl square pyramid. Two VO4 tetrahedra are connected to give stretched V2O7 double tetrahedra, and linked in planes via the oxygen corners of the CuO4Cl pyramids. The crystal structure and the structure of the complex BaO8Cl2 polyhedron are discussed.

The Growth and Characterization of the Cerium Contained Inorganic Halide Scintillators

2010 ◽  
Vol 442 ◽  
pp. 275-282 ◽  
Author(s):  
G. Rooh ◽  
Hong Joo Kim ◽  
S. Kim
Keyword(s):  
Wavelength Range ◽  
Time Constant ◽  
Decay Time ◽  
Detection System ◽  
Radiation Detection ◽  
Light Yield ◽  
Peak Position ◽  
Decay Time Constant ◽  
Broad Emission Band ◽  
X Ray

A report on the crystal growth, luminescence and scintillation characteristics of two developed scintillators, CsCe2Cl7 and Cs2NaCeCl6 are presented. CsCe2Cl7 is a new scintillation material. These crystals were grown by the Czochralski pulling technique. The X-ray diffraction technique was used to verify the structure of crystals. Under the X-ray excitation emission, the CsCe2Cl7 showed a broad emission band in the wavelength range from 370 to 470 nm while the Cs2NaCeCl6 crystal showed a spectrum in the wavelength range from 370 to 440 nm. The energy resolutions (FWHM of peak position) for the 662 keV full energy peak of 5.5% and 8.3% were observed at room temperature for the CsCe2Cl7 and Cs2NaCeCl6 crystals, respectively. The scintillation decay time measurement curves showed that, CsCe2Cl7 crystal has a single exponential decay function with a decay time of 50 ns. The Cs2NaCeCl6 crystal exhibited three main decay time components, a short component with a decay time constant of 91 ns and 36% intensity, an intermediate component with a decay time constant of 601 ns and intensity 33%, followed by a long component with a 3.2 µs decay time constant and an intensity of 31% of the total light yield. On the basis of the scintillation results of these materials grown, it is believe that these scintillation crystals can find a place in medical imaging and radiation detection system.

scholarly journals Crystallization of CsPbBr3 single crystals in water for X-ray detection

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jiali Peng ◽  
Chelsea Q. Xia ◽  
Yalun Xu ◽  
Ruiming Li ◽  
Lihao Cui ◽  
...  
Keyword(s):  
Single Crystals ◽  
Performance Metrics ◽  
Radiation Detection ◽  
Crystal Habit ◽  
X Ray ◽  
X Ray Imaging ◽  
Ionization Radiation ◽  
Halide Perovskites ◽  
Low Temperature Crystallization ◽  
Temperature Crystallization

AbstractMetal halide perovskites have fascinated the research community over the past decade, and demonstrated unprecedented success in optoelectronics. In particular, perovskite single crystals have emerged as promising candidates for ionization radiation detection, due to the excellent opto-electronic properties. However, most of the reported crystals are grown in organic solvents and require high temperature. In this work, we develop a low-temperature crystallization strategy to grow CsPbBr3 perovskite single crystals in water. Then, we carefully investigate the structure and optoelectronic properties of the crystals obtained, and compare them with CsPbBr3 crystals grown in dimethyl sulfoxide. Interestingly, the water grown crystals exhibit a distinct crystal habit, superior charge transport properties and better stability in air. We also fabricate X-ray detectors based on the CsPbBr3 crystals, and systematically characterize their device performance. The crystals grown in water demonstrate great potential for X-ray imaging with enhanced performance metrics.

Diffraction Effects from Irradiated Aluminum Single Crystals*

1962 ◽  
Vol 6 ◽  
pp. 164-171
Author(s):  
H. E. Kissinger
Keyword(s):  
Single Crystals ◽  
Crystal Surface ◽  
Irradiation Damage ◽  
X Ray Diffraction ◽  
X Ray ◽  
Integrated Intensity ◽  
Diffraction Effects ◽  
Induced Defects ◽  
Irradiation Induced Defects ◽  
Trapping Sites

AbstractThe effect of substructural perfection on the accumulation of irradiation damage in aluminum was examined. Large single crystals with extensive substructure and crystals essentially free of substructure, all with faces cut parallel to crystal planes, were subjected to neutron irradiation. Subsequent examination by X-ray diffraction revealed pronounced changes in integrated intensity and Debye-Waller temperature factor for the substructure-free crystals; these effects disappeared upon re-etching of the surface. Laue photographs showed that the normal single-crystal pattern was partially obscured by a polycrystalline effect which also disappeared upon etching. Crystals with extensive substructure showed no such effects.This diffraction evidence supports the view that irradiation-induced defects in aluminum migrate to and collect at the crystal surface if no internal trapping sites exist.

scholarly journals Über das gemischte Alkali-Erdalkalimetall-Oxoruthenat NaSr3RuO6 / The Mixed Alkaline Alkaline Earth Oxoruthenate NaSr3RuO6

1995 ◽  
Vol 50 (4) ◽  
pp. 581-584 ◽  
Author(s):  
S. Frenzen ◽  
Hk. Müller-Buschbaum
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Alkaline Earth ◽  
Partial Replacement ◽  
X Ray ◽  
Group D ◽  
Symmetry Space ◽  
Related Compounds ◽  
Symmetry Space Group ◽  
Rhombohedral Symmetry

Single crystals of NaSr3RuO6 have been prepared in closed silver tubes and investigated by X-ray techniques. This compound crystallizes with trigonal (rhombohedral) symmetry, space group D63d - R3̅c , a = 9.6069(8), c = 11.513(2) Å, Z = 6, and is isotypic to compounds of the Sr4PtO6 type. The crystal structure is discussed with respect to related compounds with partial replacement of alkaline earth elem ents by sodium and copper.

X-ray characterization of α-Fe2O3 single crystals containing 2.2% and 95% 57Fe

1998 ◽  
Vol 5 (3) ◽  
pp. 952-954
Author(s):  
J. Y. Zhao ◽  
X.-W. Zhang ◽  
M. Ando ◽  
Y. Yoda ◽  
S. Kikuta ◽  
...  
Keyword(s):  
Single Crystals ◽  
Bragg Scattering ◽  
Rocking Curve ◽  
X Ray ◽  
Fe Isotopes ◽  
Integrated Intensity ◽  
Scattering Study

α-Fe2O3 single crystals containing 2.2% and 95% 57Fe isotopes were characterized by means of X-ray topography, the diffraction rocking curve and the integrated intensity. These crystals were revealed to be nearly perfect and suitable for a further nuclear-resonant Bragg-scattering study.

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