Novel layered structures in lead–vanadate–tellurate unconventional glass ceramics

• Published in: Journal of non-crystalline solids 2010-06, Vol.356 (25), p.1267-1271
• Main Authors: Rada, M., Maties, V., Rada, S., Culea, E.
• Format: Article
• Language: English
• Subjects: Bending vibration; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductivity of specific materials; Conductivity phenomena in semiconductors and insulators; Crystal structure; Diffraction; Doping; Electrical conduction; Electronic transport in condensed matter; Exact sciences and technology; FTIR spectroscopy; Glass ceramics; Lead (metal); Lead–vanadate–tellurate glass ceramics; Mobility edges; hopping transport; Phases; Physics; Polymers; organic compounds (including organic semiconductors); X-rays
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2010.04.021

Unconventional glass ceramics with xPbO·(100 − x)[6TeO 2·4V 2O 5] general formula, where 0 ≤ x ≤ 60 mol%, were synthesized and characterized by investigations of FTIR spectroscopy and X-ray diffraction. Our results confirm the existence of the Te 2V 2O 9 and rich-V 2O 5 crystalline phases in the composition of the glass ceramics. By increasing the heat treated times up to 12 h and 18 h, respectively, the X-ray diffraction patterns reveal the apparition of the PbTeO 3 crystalline phase. These glass ceramics contain V + 4 and V + 5 ions contained in these glass ceramics are required for electrical conduction. The electrical conduction is attributed to the hopping of 3d 1 unpaired electron from V + 4 to V + 5 sites which induces a polarization of the vanadium ion around them forming a polaron. The effect of prolonged treatment on glass ceramics suggest that the doping with lead ions will distort the Te–O–Te linkages and generate the destruction of Pb–O–V and/or V–O–V bending vibrations producing the formation of the PbTeO 3 crystalline phase.