Structural Study of Modified Bi4V2O10+δPhases (δ=0, 0.5, 1): Influence of Antimony Contribution

✍ Scribed by S. Sorokina; R. Enjalbert; P. Baules; A. Castro; J. Galy

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 281 KB
• Volume: 144
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1999.8169

✦ Synopsis

Three solid solutions of general composition Bi 4؊x Sb x V 2 O 10 , Bi 4 V 4؉ 2؊y V 5؉ y O 10؉y/2 , and Bi 4 V 2؊z Sb z O 11 have been investigated in the 5vefold Bi 2 O 3 +V 2 O 5 +V 2 O 4 +Sb 2 O 3 +Sb 2 O 5 system. These oxides have been characterized by X-ray di4raction and electron microscopy techniques. Single phases have been isolated for values ranging from 0 to x, z ‫؍‬ 0.8 and y ‫؍‬ 2. Single crystals of Bi 3.2 Sb 0.8 V 2 O 10 , Bi 4 V 2 O 10.5 , and Bi 4 V 1.2 Sb 0.8 O 11 have been grown and their structures determined by X-ray di4raction methods. The three oxides crystallize in the orthorhombic system, space groups F222, Amam, and Fmmm, respectively. Their structures keep the classical two-dimensional array of Aurivillius-like oxides with (Bi, Sb)+O layers interleaved with (V, Sb)+O sheets. It has been found that Sb 3؉ is introduced into the bismuth layer, due to its similar sterical behavior, by the presence of a 5s 2 lone pair associated with Sb 3؉ and 6s 2 associated with Bi 3؉ , whereas Sb 5؉ substitutes for the V 5؉ cation. All of the substitutions carried out mainly act on the vanadium layer, which can accommodate di4erent coordination polyhedra for cations: tetrahedra for V 5؉ , square pyramids and distorted trigonal bipyramids or octahedra for V 4؉ and V 5؉ , and octahedra for Sb 5؉ . This fact can be related to the electrical properties, such as high ionic conduction and ferroelectricity, shown by these types of materials.