Synthesis, Crystal Structure, and Characterization of the New Ordered Hollandite-Type NdMo6O12

✍ Scribed by J. Tortelier; W.H. McCarroll; P. Gougeon

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 363 KB
• Volume: 136
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1997.7662

✦ Synopsis

Single crystals of NdMo 6 O 12 were prepared by fused-salt electrolysis at 960°°C from a melt of Rb 2 MoO 4 , MoO 3 , and Nd 2 O 3 having the molar ratio 8.4 : 5 : 1. The compound crystallizes in the tetragonal space group I4/m with a ‫؍‬ 9.8988(2) A s , c ‫؍‬ 8.6434(5) A s , V ‫؍‬ 846.93(5) A s 3 , and Z ‫؍‬ 4. The structure of NdMo 6 O 12 has been determined from single-crystal X-ray diffraction data and refined to reliability factors of R(F o ) ‫؍‬ 0.0409 and R w (F 2 o ) ‫؍‬ 0.0612 for all the reflections (1282). NdMo 6 O 12 adopts a hollandite-related structure with a tripled c-axis. Within the double chains of edge-sharing MoO 6 octahedra, the Mo atoms form infinite chains of Mo 3 triangular clusters. Another dominant feature of the structure is the ordering of the Nd 3؉ cations within the channels delimited by the Mo-O double strings. NdMo 6 O 12 shows semiconducting behavior along the chains with an activation energy of 0.3 eV and a room-temperature resistivity of 0.49 • cm. The magnetic susceptibility data indicate paramagnetic behavior due to the Nd 3؉ moment at high temperature.