Crystal structure of potassium molybdate, K2MoO4

Abstract

K2Mo0, crystallises in the monoclinic system, space group C2/rn, with unit-cell dimensions a = 12.348, b = 6.081, c = 7.538 8, and p = 11 5.74". Its structure, determined by three-dimensional Patterson and Fourier syntheses and refined by least-squares techniques contains isolated, almost regular MOO, tetrahedra with average Mo-0 distance 1 -76 f 0.01 A and potassium ions occupying eight-co-ordinate positions. The potassium-oxygen co-ordination may be described basically as somewhat distorted trigonal prismatic, where the K-0 distances are all <3 8, with the co-ordination polyhedron completed by two longer contacts of 3.21 8. The similarity to the P-K2S04 structure is discussed; K2W04 and [NH4I2MoO4 have been shown to be isomorphous with K2Mo04.BIFol + C]F,la) where A = 12.90, B = -1.66, and C = 0.056, was adopted and found to be satisfactory except

Modulated phase ofK2MoxW1−xO4mixed compounds using orthorhombic symmetry: A powder di

“…Crystallographic results obtained for the nonmodulated hexagonal and monoclinic phases are equivalent to those found in literature, 9,[22][23][24][25] and will not be further discussed in this paper. Concerning results found in literature, the modulated phase of K 2 WO 4 and K 2 MoO 4 has generally been interpreted using hexagonal symmetry; 10-13 however neither a superspace group nor a crystallographic model has ever been proposed to describe the referred structures.…”

Isomorphism among commensurate and incommensurate high-temperature phases of A2BO4compounds

“…At a lower temperature a destructive phase transition transforms the structure into the Iow-temperature monoclinic P-K, MOO, type (Gatehouse and Leverett, 1969). Between 753K and 681K an incommensurate phase occuys.…”

“…However, aclose look at the powder patterns shows that K, MOO, is orthorhombic in its incommensurate phase. On heating from the monoclinic room-temperature form (Gatehouse and Leverett, 1969) to just above the phase transition at 593K the diffraction lines of the main reflections are broadened. The line profile is often asymmetric and suggests unresolved split lines.…”

“…The transition is a so-called lock-in transition. The structure between 681K and 568K is of the P-K, SO, type, while below 568K the monoclinic P-K2 MOO, structure (Gatehouse and Leverett, 1969) is the stable form.…”

Two Original Infinite Chains in the New Caesium Tetramolybdate Compound Cs2Mo4O13

“…Gatehouse & Leverett (1969); (b) Kools, Koster & Rieck (1970); (c) Gonschorek & Hahn (1973); (d) Lindqvist (1950);Seleborg (1967); (e) Magarill & Klevtsova (1971 ); (f) Seleborg (1966); (g) Gatehouse & Leverett (1968); (h) Foerster, Kreusler & Fuchs (1985); (i) Gatehouse & Miskin (1974); (j) Gatehouse & Leveren (1971); (k) present work; (l) Toledano & Touboul (1978); (m) Gatehouse & Miskin (1975); (n) Toledano, Touboul & Herpin (1976). (Sheldrick, 1976) and the absorption correction program DIFABS (Walker & Stuart, 1983) did not operate well with the data.…”