The structure of sodium strontium phosphate nonahydrate

Abstract

STRUCTURE OF LITHIUM SODIUM YTTRIUM SILICATE Na2LiYSi6Ol5 many types of metasilicate rings, e.g. Si309, Si4012, Si6018, Si12036.One peculiarity of the Sechser-Doppelkette unit is that, unlike other metasilicate units, it does persist essentially unchanged in a wide variety of structures containing ions of different charges in octahedral sites, e.g. M 2+, M 3+ and M 4+, as well as different numbers of charge-balancing cations. Thus, in the series NaELiM3+Si6015, stable phase formation occurs for octahedral ions as small as Fe 3+ (0.66 A) and as large as Sm 3+ (0.96 A). The present structure determination was undertaken because Y (0.90 A) is amongst the largest trivalent ions which can be substituted in melt-grown crystals.In the compounds Na2MgESi6015, NaELiFeSi60~5, NaLiZrSi6015 and Na2LiYSi6015 the following features are observed. In the unit cells of these compounds the c axis, which is parallel to the direction of propagation of the silicate double chains and is thus a rough measure of the degree to which the chains are folded, lies in the relatively narrow range 10.072-10.375 A. Also, the Si-O-Si angles are similar in all four. Thus the silicate chain constitutes a stable and relatively inflexiblc building unit. Again, in all cases there is marked distortion of the bond angles at the tetrahedral site. We conclude, therefore, that this distortion enables the structure to accommodate a wide range of cations on the octahedral sites without necessitating changes to the Sechser-Doppelkette unit. AbstractThe crystal structure of SrNaPO4.9H20 has been determined by single-crystal X-ray diffraction. The crystals are cubic, a = 10.544 (2) A, space group P2~3, with Z = 4, Pm = 2.11, Pc = 2.083 g cm -3. The structure was refined by full-matrix least-squares techniques to R = 0.025 and R w = 0.026 for the 323 reflections used in the refinement. All cations and anions are completely surrounded by water molecules. All nine water molecules are coordinated to the same Sr 2+ ion, forming a tricapped trigonal prism. The Na + ion is coordinated to six water molecules, forming a distorted octahedron. Extensive edge-sharing of Sr(H20) 9 and Na(H20)6 polyhedra exists. The environment of the PO]-ion consists of 15 water molecules all of which are probably hydrogen bonded to PO 4 oxygens. However, there is considerable disordering of the phosphate O atoms, somewhat similar to those of SO 4 groups in alums.

A glaserite-type structure: calcium tripotassium hydrogenbis(phosphate), CaK3H(PO4)2

“…The 0(2)...0(2') distance, 2.483 A, is in the range of values, 2.40-2.55 ,~, quoted for symmetric hydrogen bonds (Hamilton & Ibers, 1968). Similar linkages of HPO4:-ions are known in several phosphates (Dickens, Bowen & Brown, 1972;Takagi, Mathew & Brown, 1980, 1982. Glaserite-type structures have been observed or can be predicted for compounds of the type (A, C)rBX 4 where A and C are cations differing in size and BX 4 is a tetrahedral anion.…”

Stable strontium isotope fractionation in synthetic barite

“…The initial guess for the configuration of each substituted 8 structure was based on modeling with empirical potentials (Wahid et al, 2002) using the GULP software package (Gale and Rohl, 2003), followed by relaxation using density functional theory. (Mathew, 1998;Ricci et al, 2005) (Takagi et al, 1982;Agron and Busing, 1986;Abrahams and Vordemvenne, 1995). 88 Sr/ 86 Sr fractionations in SrO and SrF 2 can 9 also be calculated using well-calibrated empirical force field models, providing an important check on model accuracies.…”

Crystal structure of sodium strontium monothiophosphate nonahydrate, NaSr[PO3S] · 9H2O

“…The present work is a continuation of structural studies of thiophosphates [9,10]. The crystal structure of title compound is isotypic to those of NaMPO 4 · 9H 2 O (M = Ba, Sr) [11,12] …”