Preparation, crystal structure, and luminescence of magnesium molybdate and tungstate monohydrates, MgMoO4 · H2O and MgWO4 · H2O

Abstract

Triclinic MgMo04 . Hz0 and the isomorphous MgW04 . Hz0 have been prepared under mild hydrothermal conditions in single crystalline form and the crystal structure of MgMo04 . Hz0 has been determined by X-ray diffraction. The structure is compared to a model deduced earlier for MgWO., . Hz0 from topotaxy data, with which the general topology agrees, but there is an important difference in the orientation of Moo,-tetrahedra. The X-ray powder diffraction data, thermal dehydration behavior, as well as the luminescence properties are reported and the latter compared with data of related phases. Crystal data are: Triclinic, space group P -1; MgMoOa . HzO: a = 5.665 A, b = 5.869 A, c = 6.875&a= 100.80",/3 = 95.05",y= 106.57";MgWO~~H~O:a = 5.681&b = 5.887&c= 6.870& a = 100.85", p = %.44", y = 106.55". D

Silver Molybdate and Silver Tungstate Nanocomposites with Enhanced Photoluminescence

“…In contrast, the obtained silver tungstate is a mixture of the two orthorhombic α - and hexagonal β - allotropes, where the latter is strongly dominant. This result was actually unexpected, as the stable phase is the α - phase and was systematically obtained by various methods [17,22,40,44–46], including the “coprecipitation” approach proposed by Calvacante [15]. Indeed, the β -phase was previously obtained only by precipitation in ice water at pH 9 [16], or as metastable hollow spheres, using PMMA cross-linked micelles as templates [18].…”

“…Metal molybdates, another important family of inorganic materials, have also been intensively investigated because of their various properties, one of these being photoluminescence [22–24]. Several studies have been carried out to explore the properties and practical applications of silver molybdate Ag 2 MoO 4 , which exist in two forms, α -tetragonal [25] and β - cubic [26–27].…”

Octahedral–tetrahedral framework structures of InAsO4·H2O and PbIn(AsO4)(AsO3OH)

“…1 and 2 linkage results in a three-dimensional framework with small voids into which the apical water ligand (OW5) of the InO 5 (H 2 O) octahedron points. The positions of the H atoms in (I) are close to those in MgMoO 4 ÁH 2 O (Amberg et al, 1988). The hydrogen bonds are of medium strength (Table 2).…”

“…Compound (I) is a previously unknown indium arsenate compound. It has a triclinic crystal structure (space group P1) and is isotypic with its Sc analogue ScAsO 4 ÁH 2 O (Kolitsch & Schwendtner, 2004), its phosphate analogue InPO 4 ÁH 2 O (Tang & Lachgar, 1998), the vanadate schubnelite Fe III VO 4 ÁH 2 O (Schindler & Hawthorne, 1999), and the molybdates and tungstates M II XO 4 ÁH 2 O (M = Mg and Mn; X = Mo and W; Clear®eld et al, 1985;Amberg et al, 1988).…”

Crystal structure of scandium arsenate(V) monohydrate, ScAsO4 · HO, the first MnMoO4 · H2O-type arsenate

“…ScAsC>4 -H2O formed tiny indistinct colorless plates. and the molybdates and tungstates Ai"X0 4 • H 2 0 (M = Mg, Mn; X = Mo, W) [8,9]. Thus, the title compound represents the first arsenate within this small family of isotypic oxysalts which contain Af20g(H20)2 (M= di-or bivalent metal) dimers built of edge-sharing MOf, octahedra (see below for more details).…”