Structure of kamiokite

Abstract

Fig. 4 shows the DTA curve recorded between 240 and 130K. A small endothermic peak occurs at 168 (2)K. The peak is completely reversible with a slight hysteresis of about 5 K. Because the base line is not completely linear an exact value for the change in free enthalpy and consequently in the entropy should not be estimated. The peak in the DTA curve lies in the same temperature range as observed in the magnetic susceptibility curve (Fig. 3).The structure of the title compound shows an unusual connection scheme with edge-and face-sharing octahedra. This leads to distorted V(S,Se) 6 octahedra with short metal-metal bonds in the structure. The partial itinerant character of this compound is supported by the magnetic measurements. The discontinuity in the magnetic-susceptibility curve and the endothermic peak in the DTA curve are a clear indication for a phase transition at around 170K. Further investigations are in progress to clarify the nature of this phase transition.

Structurally based prediction of ferroelectricity in inorganic materials with point group 6mm

“…The atomic coordinates of Fe2Mo30 s, also known as the mineral kamiokite, have been independently determined and refined by three different groups; the most recent values (Kanazawa & Sasaki, 1986) are given in Table 4. With lattice constants of a=5-781 (1), c= 10.060 (1)A at 298 K, refinement with 656 independent reflections IF o > 3tr (Fo)] based upon a model with anisotropic thermal parameters for all atoms gave R =0.027.…”

Intermediate States on the Way to Edge‐Sharing BO4 Tetrahedra in M6B22O39⋅H2O (M=Fe, Co)

“…This is longer than the mean FeÀO bond length of 199.3 pm in Fe II 2 Mo IV 3 O 8 , which exhibits Fe II O 4 tetrahedra as well. [38] In Co 6 B 22 O 39 ·H 2 O, the bond lengths of the six-coordinate cations vary from 200.4 to 250.2 pm with an average value of 212.9 pm. This value is in agreement with the average Co 2 + À O distance of six-coordinate cobalt atoms of 212.2 pm, found in Co 2 B 2 O 5 .…”

Li2GeMo3O8: a novel reduced molybdenum oxide containing Mo3O13cluster units

“…Later, a refinement of the structure was accomplished by Ansell & Katz (1966) with an R factor of 0.069. Among the above compounds, it is interesting to note that Fe 2 Mo 3 O 8 is a mineral known as kamiokite (Kanazawa & Sasaki, 1986 View of the crystal structure of Li 2 GeMo 3 O 8 in a projection approximately along [010]. Displacement ellipsoids are drawn at the 97% probability level.…”