[beta]-BaV[sub 2](P[sub 2]O[sub 7])[sub 2]: A new polymorph of barium vanadium (III) pyrophosphate characterized by intersecting tunnels

Journal Article · Wed Jun 01 04:00:00 EDT 1994 · Journal of Solid State Chemistry; (United States)

DOI:https://doi.org/10.1006/jssc.1994.1171· OSTI ID:6880868

Hwu, Shiou-Jyh; Carroll, R I; Serra, D L ^[1]

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1. Rice Univ., Houston, TX (United States)

Investigation into the synthesis of reduced vanadium phosphate has led to the formation of a new form of the barium vanadium (III) pyrophosphate compound [beta]-BaV[sub 2](P[sub 2]O[sub 7])[sub 2]. It is a polymorph of the previously known BaV[sub 2](P[sub 2]O[sub 7])[sub 2], which is now labeled as the [alpha]-phase. The title compound crystallizes in the P-1 (No. 2) space group with a = 6.269 (1) [angstrom], b = 7.864 (3) [angstrom], c = 6.1592 (9) [angstrom], [alpha] = 101.34 (2)[degree], [beta] = 105.84 (1)[degree], and [gamma] = 96.51 (2)[degree]. The structure consists of corner-shared VO[sub 6] octahedra and PO[sub 4] tetrahedra that are connected in V-O-P-O-V and V-O-P-O-P-O-V bonding arrangements. This interesting three-dimensional framework is characterized by seven types of intersecting tunnels, three of which are occupied by the barium cation, while the others are empty. It is important to know that one of the empty tunnels has a relatively large window with a minimum diagonal distance of 4.4 [angstrom], which facilitates a possible framework for a lithium ion insertion reaction. The barium atom has a 10-coordination sphere, BaO[sub 10], in which the oxygen atoms can be viewed as forming two intersecting pseudohexagonal planes. [beta]-BaV[sub 2](P[sub 2]O[sub 7])[sub 2] appears to form at a relatively higher temperature than its polymorph, [alpha]-BaV[sub 2](P[sub 2]O[sub 7])[sub 2]. A detailed structural analysis and structural comparison with the [alpha]-phase, as well as a brief comparison with SrV[sub 2](P[sub 2]O[sub 7])[sub 2], are presented.

• OSTI ID: 6880868
• Journal Information: Journal of Solid State Chemistry; (United States), Journal Name: Journal of Solid State Chemistry; (United States) Vol. 110:2; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHEMICAL PREPARATION
CRYSTAL STRUCTURE
OXYGEN COMPOUNDS
PHASE STUDIES
PHOSPHORUS COMPOUNDS
PYROPHOSPHATES
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS