The Alkali-Poor Part of the Pseudoternary Triangle AX/BX₂/MX₃:  Crystal Structures, Properties, and Potentials of (Alkali)/Alkaline-Earth/Rare-Earth Chloride Materials

Abstract

Halides of mono-, di-, and trivalent metals of the general formulas AX, BX2, and MX3 may react with each other, forming a large variety of ternary and even quaternary phases in the solid state. Aside from the alkali-poor quaternary chlorides of the ABMX6 type, which are derivatives of the UCl3 type of structure, the alkali cation free pseudoternary chlorides that form in the systems BCl2/MCl3, especially with B = Ba, are reviewed. Examples of ternary chlorides are Ba2EuCl7, with isolated [EuCl7] monocapped trigonal prisms; Ba2Cl[ScCl6], with isolated octahedra [ScCl6] and lonesome Cl-; Ba8[{(Sm6)Z}Cl32], and Ba9[{(Sm6)Z}Cl34], with Z being presumably an oxide ion residing in the large hole of the [Sm6Cl36] polyhedral clusters that occur in these fluorite type superstructures; and, finally, BaGdCl5, with corrugated layers of edge-connected [GdCl8] square antiprisms. These halides may be cationic conductors (AgSrSmCl6), insulating mixed-valence halides such as NaNd2Cl6, or semiconductors such as Pr2Br5 with interesting magnetic ordering at lower temperatures, or they may serve as hosts for luminescent ions. Ba2ErCl7, for example, is an efficient near-infrared to near-ultraviolet upconversion material.

Ba11La4Br34: a new barium lanthanum bromide

“…Similar structure types have been observed in ternary alkaline earth and rare earth fluorides (Bevan et al 1980;Bevan et al 1982;Burns et al 1968), chlorides (Liu & Eick 1988;Liu & Eick 1999;Löchner & Blachnik 2011;Meyer & Masselmann 1998), and bromides (Masselmann & Meyer 1999;Liu & Eick 1989) and in mixed valent rare earth halides (Druding & Corbett 1961;Liu & Eick 1991). These superstructures follow the general formula of M n X 2n+5 forming either a rhombohedral (n = 14) or tetragonal (n = 15) structure and consists of [M 6 ZX 36 ] polyhedral clusters (Meyer & Wickleder 2000).…”

“…For a detailed study of the luminescence properties of the title compound, see : Eagleman et al (2011). Similar structure types to that of the title compound have been observed in ternary alkaline earth and rare earth fluorides (Bevan et al, 1980(Bevan et al, , 1982Burns et al, 1968), chlorides (Liu & Eick, 1988Lö chner & Blachnik, 2011;Meyer & Masselmann, 1998), and bromides (Masselmann & Meyer, 1999;Liu & Eick, 1989) and in mixed valent rare earth halides (Druding & Corbett 1961;Liu & Eick, 1991). For structural details of simple and complex halides, see: Meyer & Wickleder (2000).…”

“…For structural details of simple and complex halides, see: Meyer & Wickleder (2000). For structural details of these types of superstructures, see : Meyer & Masselmann (1998 displays high luminosities making them attractive as a promising scintillators. A detailed study of the luminescence properties will be presented in a future publication (Eagleman et al 2011).…”

Synthese und Kristallstruktur von Ba6ZnIn2Cl20

“…Ba 2+ has coordination numbers of eight and nine. There are chloride ions that do not belong to Zn 2+ or In 3+ so that the formula may be written as Ba 12 Einleitung Im Zusammenhang mit systematischen Untersuchungen der Systeme BaCl 2 /MCl 3 (M = La, Ce±Lu, Y, Sc) [1,2] wurden u. a. die terna È ren Chloride BaGdCl 5 [3], Ba 2 LuCl 7 [2] und Ba 2 Cl[ScCl 6 ] [4] erhalten und strukturell aufgekla È rt. Da der Ionenradius von In 3+ fu È r die Koordinationszahl 6 mit 94 pm angegeben wird (¹Kristallradienª nach Shannon [5]) und sich damit zwischen die Selten-Erd-Ionen Lu 3+ (100 pm) und Sc 3+ (88 pm) einreiht, lag es nahe, auch das System BaCl 2 /InCl 3 in die Untersuchungen einzubeziehen.…”

High energy resolution scintillators for nuclear nonproliferation applications

“…Each of these ternary compounds has an alkaline earth or rare earth sites and thus, they are ideal host compounds for the Eu 2+ or Ce 3+ activator to obtain 5d-4f luminescence in the blue region [13]. The phase diagrams, formability and crystal chemistry of the corresponding ternary compounds have been extensively studied [14][15][16][17][18]. Potassium-containing compounds were not excluded from the list of potential scintillator candidates in our exploratory work despite the existence of intrinsic radioactivity from naturally occurring 40 K. The emission of 1.46 MeV gamma rays from 40 K may exclude these scintillators from some, but certainly not all, applications.…”