EuI₂, a low-temperature europium(II) iodide phase

Abstract

Light-yellow europium(II) diiodide, prepared by the low-temperature reaction of europium and ammonium iodide in liquid ammonia at 200 K and characterized by high-resolution X-ray powder diffraction, represents a new phase for EuI2 that adopts an orthorhombic Pnma structure with all three atoms lying on 4c positions (.m.). It is isotypic with SrI2(IV). Temperature-dependent X-ray measurements performed to investigate the thermal stability of the new phase show that it decomposes irreversibly to amorphous material around 673 K. Total-energy density-functional calculations using the generalized gradient approximation suggest this to be the ground-state structure of EuI2.

Preferential Eu Site Occupation and Its Consequences in the Ternary Luminescent HalidesAB2I5∶Eu2+Fang1, Biswas2 2015Phys. Rev. Applied15340View full textAdd to dashboardCite

“…10 In this context the proposed Sr, Bamixed ABa VIII Sr VII I 5 :Eu family are promising where the Eu 2+ are likely to remain confined at the B2 (VII) site, considering the fact that Eu in ground state of EuI 2 are seven coordinated. 42,43 While the scintillation decay times in the order of several hundred ns observed in CsBa 2 I 5 :Eu 2+ and KSr 2 I 5 :Eu 2+ are unsuitable for medical imaging techniques, the mixed cation approach mentioned here may help reduce self-absorption for faster response while resisting the formation of Eu-rich aggregates or domains. Other contributing factors such as better management of intrinsic and extrinsic defects from a materials standpoint and proper integration with a photosensor will also need to be addressed for optimum detector performance.…”

“…[29][30][31][32][33][38][39][40] We also employed hybrid functional (PBE0) 40 One is orthorhombic and the other is monoclinic. 42,43 In both forms the Eu ions are seven-fold coordinated. In Table I the Eu-I bond-lengths in the orthorhombic cell are listed.…”

“…In Table I the Eu-I bond-lengths in the orthorhombic cell are listed. 42 Calculated host energy gaps (E g ), the gap between the halfoccupied Eu-4f and the conduction band minimum (hereinafter 4f-CBM), and the orbital character of the CBM are also given in (Table I). 42 We conclude that the large size mismatch between Eu and Ba at the eight-coordinated site, and the ability to form shorter sevencoordinated Eu2 (VII) -I bonds is the likely reason for the preferential occupation of the B2 (VII) sites in KBa 2 I 5 :Eu 2+ .…”

Defect chemistry of Eu dopants in NaI scintillators studied by atomically resolved force microscopy

“…The precipitated phase observed in Fig. 3 is inconsistent with the cubic Suzuki structure, and also does not match any known bulk structure of EuI 2 [36]. The moire pattern indicates that the precipitate is a 2D sheet, weakly bound to the substrate.…”

Reactions in Anhydrous Liquid Ammonia: Syntheses and Crystal Structures of [M(NH3)8]I2 (M = Eu, Yb) with Bicapped Trigonal‐Prismatic Octaammine Lanthanoid(II) Cations

“…However, the intermediate formed inside the liquid ammonia solution remained unclear. [6] It has been reported that the solutions of Eu and Yb likely contain hexaammine complexes [M(NH 3 ) 6 ] 2+ •2e -(M = Eu, Yb). [7] From the reactions of these two metals with AgN 3 as an oxidant in liquid ammonia, we obtained octaammine complexes of Eu II 3 .…”