Synthesis of Bi(Cu)VO x compounds by means of a monomode microwave : Crystallographic, calorimetric, electrical and low temperature magnetic properties

• Published in: Journal of alloys and compounds Vol. 309; no. 1; pp. 219 - 224
• Main Authors: Gasgnier, M, Petit, A, Gardette, M.-F, Rivière, E, Launay, S, Dworkin, A, Toscani, S
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2000
• Subjects: Bismuth(copper)vanadium oxides; Electrical conductivity; High ionic conductors; Microwave; Phase transitions; Electrical conductivity; Bismuth(copper)vanadium oxides; Microwave; High ionic conductors; Phase transitions
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/S0925-8388(00)01054-9

BiVO x and Bi(Cu)VO x compounds exhibit various phases as a function of temperature. Syntheses performed by means of a monomode microwave allows the high copper ionic conductor γ-Bi 4Cu x V 2− x O 11 phase to be obtained rapidly (less than 5 min). After heating at about 830 K, large crystals, characteristic of this phase, are formed. X-ray diffraction patterns show that this phase coexists with the Bi 4Cu 3V 2O 14 and BiVO 4 compounds. DSC measurements show on heating the presence of an exothermic peak and two endothermic peaks. On cooling one exothermic peak occurs. Electrical conductivity (under air and oxygen) exhibits for the ionic phase a large scale of values which are close to those previously obtained for a purer material. Magnetic measurements show that the γ-phase is strictly antiferromagnetic between 300 and 2 K. The results are discussed in terms of polytypic structures, and of performances carried out by means of the monomode microwave.