Crystal Structure of the Transition-Metal Molybdates. I. Paramagnetic Alpha-MnMoO4

Abstract

Paramagnetic alpha-MnMoO4, the stable phase at STP, is monoclinic with lattice constants a=10.469±0.005, b=9.516±0.005, c=7.143±0.005 Å, and β=106°17′±6′, and space group C2/m. The crystal structure has been solved and refined by a combination of three-dimensional Patterson and Fourier series and by the method of least squares. 1873 independent integrated intensities were measured by PEXRAD; the final agreement factor between measured and calculated structure factors is 0.0574. Two crystallographically independent Mn atoms are surrounded by highly distorted oxygen octahedra; the Mn–O distance varies between 2.091±0.006 and 2.252±0.003 Å, with average length 2.164 Å. Two crystallographically independent Mo atoms are surrounded by slightly distorted oxygen tetrahedra, with Mo–O distances ranging from 1.724±0.005 to 1.851±0.004 Å, the average being 1.761 Å. The thermal vibrations are significantly anisotropic. An analysis is given of various current methods for estimating the standard deviation in the measured structure factor.

Sodalite, Na4Si3Al3O12Cl: structure and ionic mobility at high temperatures by neutron diffraction

“…Symmetry-equivalent F2o (losin20) observations in each data set were averaged giving the independent reflections (Table 1) used in refinements. The variances 2 2 cr o(Fo ~) taken for S1 data were averages of counting statistics values; those taken for $2 data were the larger of the population and counting statistics (Abrahams & Reddy, 1965).…”

CaWO4: A New High-Pressure and High-Temperature Phase

“…These lattice parameters were obtained using the LeBail extraction technique [9] available in the GSAS program [7]. The C2/m structure has been observed previously in other binary oxides related to CaWO 4 , being its prototype MnMoO 4 [10]. Therefore we have assumed the atomic position parameters of MnMoO 4 to perform the LeBail refinement.…”

Design of Mixed‐Metal Silver Decamolybdate Nanostructures for High Specific Energies at High Power Density

“…A x MoO z types of materials are the special class of inorganic oxide materials which possess mixed state of conductivity (ionic as well as electronic), however, their physical, chemical, and electrochemical properties are largely dependent on the crystal structure (arrangement of the octahedra and tetrahedra in the unit cell). [22,23] Besides, multiple oxidation states of molybdenum ions (Mo 3+ to Mo 6+ ), molybdates of metal or transition metal elements provide robust chemical stability (due to covalent bonding) and excellent ionic conductivity with respect to the electrolyte ions due to the conductive paths paved with metal or transition metal ions. [25,26] Recently, Mai et al [21] demonstrated the use of transition metal molybdates, i.e., CoMoO 4 in nanowire-like morphology as an electrode in pseudocapacitors with a specific capacitance of 62.8 F g −1 (at a current density of 1 A g −1 in a potential window of ΔV = 1 V), and further improved the capacitance to 187 F g −1 (at a current density of 1 A g −1 ) by forming heterostructure of MnMoO 4 /CoMoO 4 nanowires.…”

“…[14] Polyacid salts of molybdenum, A x MoO z (where A could be a monovalent, divalent, or trivalent metal ion), [15] are interesting host materials for ion insertion applications, particularly in electrochemical energy-storage devices, i.e., batteries [16][17][18] and supercapacitors. [19][20][21] Due to their unique crystal structure (layers of molybdenum oxide octahedra separated by the metal ions), metal-molybdates [22][23][24] become the subject of increasing research interest. A x MoO z types of materials are the special class of inorganic oxide materials which possess mixed state of conductivity (ionic as well as electronic), however, their physical, chemical, and electrochemical properties are largely dependent on the crystal structure (arrangement of the octahedra and tetrahedra in the unit cell).…”