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

Abstract Unconventional glass ceramics with x PbO·(100 − x )[6TeO 2 ·4V 2 O 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 2 V 2 O 9 and rich-V 2 O 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.