Low-temperature Crystal Structures and Magnetic Properties of the V-4-Cluster Compounds Ga1-xGexV4S8

作者：Bichler Daniel; Slavik Herta; Johrendt Dirk^*

来源：Zeitschrift fur Naturforschung Section B-A Journal of Chemical Sciences, 2009, 64(8): 915-921.

DOI：10.1515/znb-2009-0807

• Correlated Materials
• Cluster
• Spinel
• Crystal Structure
• Magnetism

Solid solutions Ga1-xGexV4S8 (x = 0-1) were synthesized by solid-state reactions and characterized by temperature-dependent X-ray powder diffraction and static magnetic susceptibility measurements. The Compounds crystallize in the cubic GaMo4S8-type Structure (space group F (4) over bar 3m), built tip by heterocubane-like [V4S4]((5-x) ) cubes and [Ga1-xGexS4]((5-x)-) tetrahedra arranged in a NaCl-like manner. The successive substitution of Ga3 by Ge4 increases the electron Count in the molecular orbitals (MO's) of the V-4-cluster gradually from seven to eight. We observe ail almost linear increase of the magnetic moments, connected with a transition from ferromagnetic to antiferromagnetic ordering around x approximate to 0.5. Remarkably, low-temperature structural phase transitions as known from the ternary Compounds were also detected in the solid solutions. The gallium-rich compounds (0 <= x < 0.5) undergo rhombohedral distortions like GaV4S8 (space group R3m), whereas distortions to orthorhombic symmetry (space group lmm2) as known from GeV4S8 occur in the germanium-rich part of the solid solutions (0.5 <= x <= 1).

• 出版日期2009-8