Synthesis, Structural Studies, and Physical Properties of the RE5Mo32O54 (RE=La, Ce, Pr, Nd) Compounds Containing trans-Bicapped Mo8 Octahedral Clusters and Mo7–Mo10–Mo7 Triclusters

✍ Scribed by J. Tortelier; P. Gall; H. Noël; P. Gougeon

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 240 KB
• Volume: 152
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2000.8697

✦ Synopsis

Polycrystalline samples and single crystals of the RE 5 Mo 32 O 54 compounds (R ‫؍‬ La, Ce, Pr, and Nd) were synthesized by solid state reactions at high temperature in sealed Mo crucibles. Their crystal structures were determined by single crystal X-ray diffraction methods. All four compounds are isostructural and crystallize in the monoclinic P2 1 /c space group. Their crystal structure exhibits two di4erent cluster types: an isolated bicapped octahedral Mo 8 cluster having an isomeric trans form and a Mo 24 chain fragment that can be described as Mo 7 +Mo 10 +Mo 7 triclusters. The oxygen atoms bridge all Mo+Mo edges or are linked to free apices. Both Mo 8 O 24 and Mo 24 O 60 cluster units are arranged in layers parallel to the ac plane. These compounds show semiconducting behavior with activation energies of about 0.06 eV and room temperature resistivities in the range 0.04+0.08 ' cm. The magnetic susceptibility data reveal a magnetic moment of 1.77 B localized on the Mo sublattice in addition to that arising from the rare-earth ions.