Synthesis and Crystal Structure of a New Mixed Orthovanadate-Pyrovanadate Series: MBa2V3O11 or MBa2V2PO11 with M = Bi, In, or a Rare Earth
✍ Scribed by Jinfan Huang; Qiuyi Gu; Arthur W. Sleight
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 435 KB
- Volume
- 110
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
A new series of vanadates with the general formula (M \mathrm{Ba}{2} \mathrm{~V}{3} \mathrm{O}{11}), where (M) may be (B i), In, or a rare earth, has been synthesized and structurally characterized by single crystal X-ray diffraction and powder X-ray diffraction. The general formula may be rewritten as (M \mathrm{Ba}{2}\left(\mathrm{VO}{4}\right)\left(\mathrm{V}{2} \mathrm{O}{7}\right)) to emphasize that there is one orthovanadate group and one pyrovanadate group in each formula unit. Up to one-third of the vanadium may be replaced by phosphorous, leading to the general formula (M \mathrm{Ba}{2} \mathrm{~V}{2} \mathrm{PO}{11}). However, phosphorous shows no preference between the ortho and pyro groups. Both (M \mathrm{Ba}{2} \mathrm{~V}{3} \mathrm{O}{11}) and (M \mathrm{Ba}{2} \mathrm{~V}{2} \mathrm{PO}{11}) crystallize in the monoclinic system with the space group (P 2_{1} / c) and (Z=4). The cell parameters from single crystal X-ray data of (\mathrm{BiBa}{2} \mathrm{~V}{3} \mathrm{O}{11}) are (a=12.332(4) \AA, b=) 7.750(4) (\AA, c=11.279(4) \AA, \beta=103.22(3)^{\circ}, V=1049(1) \AA^{3}); and for (\mathrm{BiBa}{2} \mathrm{~V}{2} \mathrm{PO}{11}) are (a=12.266(2) \AA, b=7.615(2) \AA, c=) 11.312(2) (\AA, \beta=103.32(2)^{\circ}, V=1028.2(2) \AA^{3}). The Bi atom coordinates to six oxygen atoms forming a distorted octahedron, and the edge sharing of (\mathrm{BiO}{6}) octahedra results in a (\mathrm{BiO}{4}) chain along the (b) axis. There are two types of (\mathrm{Ba}) atoms with coordination numbers of 10 and 11 . There are three types of tetrahedral (T) atoms in these structures. The nonequivalent (T) atoms of the pyro group give (\mathrm{T}-\mathrm{O}-\mathrm{T}) angles of 167 and (171^{\circ}) in (\mathrm{BiBa}{2} \mathrm{~V}{3} \mathrm{O}{11}) and (\mathrm{BiBa}{2} \mathrm{~V}{2} \mathrm{PO}{11}), respectively. Isostructural (M \mathrm{Ba}{2} \mathrm{~V}{3} \mathrm{O}_{11}) compounds were prepared in which (M) is In, (\mathrm{La}, \mathrm{Ce}, \mathrm{Pr}, \mathrm{Nd}, \mathrm{Sm}, \mathrm{Eu}, \mathrm{Gd}, \mathrm{Tb}), Dy, Ho, Er, Yb, or Lu. O 1994 Academic Press, Inc.