Scintillating Metal‐Organic Frameworks: A New Class of Radiation Detection Materials

Abstract

The detection and identification of subatomic particles is an important scientific problem with implications for medical devices, radiography, biochemical analysis, particle physics, and astrophysics. In addition, the development of efficient detectors of neutrons generated by fissile material is a pressing need for nuclear nonproliferation efforts. A critical objective in the field of radiation detection is to obtain the physical insight necessary for rational design of scintillation materials. Many factors affect the quantum efficiency and timing of scintillator light output, including chemical composition, electronic structure, interchromophore interactions, crystal symmetry, and atomic density. None of the material types currently used in radiation detection, which include crystalline inorganic compounds such as LaBr 3 :Ce, organic compounds, and plastics, have the inherent synthetic versatility to exert systematic control over these factors. Therefore, it is likely that major advances in radiation detection will require the development of new materials outside the scope of traditional scintillators. Here, we propose that metal-organic frameworks (MOFs) could potentially offer the desired level of structural control, leading to an entirely new class of radiation detection materials.MOFs are crystalline materials consisting of metal clusters linked by coordinating organic groups. Yaghi, O'Keefe, and coworkers have shown that structures resulting from the selfassembly of specific metal ions and linkers can be predicted through an understanding of the geometric nets accessible to particular metal-linker combinations (''reticular chemistry''), [1][2][3]

Towards Bright and Fast Lu3Al5O12:Ce,Mg Optical Ceramics Scintillators

“…Furthermore, the deep trapping defects that compete with the luminescent centers for charge-carrier capture could be permanently fi lled and made inactive by a pre-irradiation process. As a result of such a procedure, a signifi cant improvement in the stability of both the RL effi ciency and light yield was indeed obtained in several scintillator single crystals like BaAl 4 [34][35][36] For LuAG:Ce, a RL increase of about 30% was noticed after an X-irradiation at 50 Gy. [ 36 ] Such a process could possibly work also for LuAG:Ce,Mg ceramics and give rise to a further improvement of their performance.…”

“…[ 18,19 ] However, differently from the laser process, which involves localized excitations, carrier migration to the luminescent centers during the scintillation process could be severely delayed by point defects induced by sintering agents. As a result, the commonly used simultaneous introduction of sintering agents like (C 2 H 5 O) 4 Si (tetraethyl ortho-silicate, TEOS) and MgO in laser ceramics induces a transparency improvement accompanied unfortunately by a deterioration of the scintillation properties. [ 20 ] Therefore, strategies different from those employed for laser ceramics should be investigated and developed to simultaneously improve the optical quality and performance of ceramic scintillators.…”

Exchange of a Tetrapositive Cation into a Zeolite and a New Inorganic Scintillator. I. Crystal Structures and Scintillation Properties of Anhydrous Zr1.7Tl5.4Cl1.7–LTA and Zr2.1Tl1.6Cl3.0–LTA

“…Therefore no attempt was made to separate O1 into two or more positions. Because O3' was closer to Zr11 and O2' was farther from Zr11, as would be expected for a small 4+ cation, the occupancies at O3' and O2' were fixed to be three times (20), and the Zr11-Cl11 bond length, 1.89(5) Å, indicate that the ions at Cl11 are bonded to Zr11 as seen in crystal 1. Zr11/Cl11 was therefore constrained to be 1.0 as in crystal 1 (step 9 in Table 3b).…”

Application of in-situ ion irradiation TEM and 4D tomography to advanced scintillator materials

“…1,3 Materials being investigated as novel inorganic scintillator materials to meet these needs include self-activated or Ce-activated compounds, polycrystalline ceramics, metal-organic frameworks, and nanoparticles all with the goal of competing with the current benchmarks NaI:Tl, CsI:Tl, and BGO. 1,4 Cadmium tungstate (CdWO 4 ) has been used as a bulk single crystal scintillator for decades due to its high density, large light output, radiation hardness, ease of use (non-hygroscopic), high emission efficiency, low level of radioactive contamination, and low afterglow. 2,5,6 While this material works for some applications, there is desire to expand its use by eliminating the issues caused by single crystal processing.…”