Synthesis, structure determination and electrical properties of β-K0.399V2.623W0.377O7.5 with mixed occupation of vanadium and tungsten elements

• Published in: Materials science in semiconductor processing Vol. 63; pp. 161 - 168
• Main Authors: Belkhiri, S., Mezaoui, D., Pérez, O.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2017; Elsevier
• Subjects: Bannermanite; Chemical Sciences; Cristallography; Crystal growth; Material chemistry; or physical chemistry; Semiconductor; Structure determination; Theoretical and; Vanado-tungsto oxide; Crystal growth; Semiconductor; Structure determination; Vanado-tungsto oxide; Bannermanite
• ISSN: 1369-8001; 1873-4081
• DOI: 10.1016/j.mssp.2017.02.014

The title compound vanadium-tungsten mixed oxide bronze K0.399V2.623W0.377O7.5 was prepared by solid state reaction at 700°C in an evacuated silica ampoule. The single crystal K0.399V2.623W0.377O7.5 crystallizes in the monoclinic system, C2m (n°12) space group, with cell parameters a =15.7123 (3)Å, b =3.6796 (6)Å, c =10.2092 (2)Å and β=108.994°(4).This phase is isostructural to β-KxV2O5 called: Bannermanite family with x ranging between 0.19 and 0.4. The structure determination shows that the framework consists of tunnels which are created by the junction of two kind of connection by the edge and the corners of VO5 square pyramid and (VO6, MO6) octahedra. The “M” metal site is statistically occupied by 62.3% of vanadium and 37.7% of tungsten. The vanadium atoms are observed in irregular octahedra forming a short bond (1.6–1.67Å) related to the double bond character (V˭O). The structure refinement led to reliability factors R=0.046, Rw=0.0377 and GOF =1.23. According to the calculated values of the activation energy, the electrical conductivity measurement as function of various temperatures ranging (between 400 and 625K) and frequency (100–105Hz) shows a semi-conductor behavior for K0.399V2.623W0.377O7.5.