Related Experiment Video
Updated: Jun 9, 2026

Synthesizing Sodium Tungstate and Sodium Molybdate Microcapsules via Bacterial Mineral Excretion
Published on: January 30, 2018
Crystal structures of two hydrous sodium potassium molybdates: Na3K(MoO4)2(H2O)9 and NaK(MoO4)(H2O)
1University of Innsbruck, Institute of Mineralogy & Petrography, Innrain 52, A-6020 Innsbruck, Austria.
Abstract:
Single-crystals of the hydrated sodium potassium orthomolybdate phases Na3K(MoO4)2(H2O)9, tris-odium potassium bis-(orthomolybdate) nona-hydrate, and NaK(MoO4)(H2O), sodium potassium orthomolybdate monohydrate, were obtained as by-products in a flux growth experiment aiming on the synthesis of silicates from the quaternary system Na2O-K2O-CaO-SiO2. The asymmetric unit of Na3K(MoO4)2(H2O)9 (space group P63/m, Z = 2) comprises one Na+ atom and one water mol-ecule on a mirror plane, one K+ atom on a 6 axis, one Mo6+ cation and one O atom on a threefold rotation axis, and one O atom and one water mol-ecule in general sites. The crystal structure is built from isolated MoO4 tetra-hedra, which are linked by common corners to trimers containing three face-sharing Na(H2O)4O2 octa-hedra. Linkage between the heteropolyhedral groups is provided by potassium cations, which are coordinated by six water mol-ecules in form of trigonal prisms. The resulting layers are located at z = 1/4 and z = 3/4, respectively. Intra- and inter-layer hydrogen bonds between the water mol-ecules and the oxygen atoms of the MoO4 tetra-hedra consolidate the structure. The backbone of the crystal structure of NaK(MoO4)(H2O) (space group P212121, Z = 4) is made from chains of edge-sharing Na(H2O)2O4 octa-hedra running parallel [100], which are decorated by MoO4 tetra-hedra via corner sharing. Neighbouring heteropolyhedral chains are linked by additional potassium cations, which are coordinated by seven oxygen ligands and one water mol-ecule. Moreover, intra- and inter-chain hydrogen bonds exist.
Related Concept Videos
Ionic Crystal Structures
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
Ionic Compounds: Formulas and Nomenclature
Qualitative Analysis
For instance, group IV...
Molecular and Ionic Solids
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
Lewis Structures of Molecular Compounds and Polyatomic Ions
Electron Configuration of Multielectron Atoms

