JOURNAL OF MATERIALS SCIENCE 27 (1992) 1343 1346 Spectroscopic and DSC studies of vanadium-copper-phosphate glasses A. A. KUTUB, F. H. AL-GHORABIE, S. S. NATTO Department of Physics, Umm AI-Qura University, Makkah, Saudi Arabia A. M. ALSANOOSI, S. S. BABKAIR, A. S. FAIDAH Department of Physics, King Abdulaziz University, Jeddah, Saudi Arabia A series of glass samples were prepared from admixtures of P205, V2O 5 and CuO and results are reported for optical absorption, infrared absorption spectra and differential scanning calor- imetry (DSC) as a function of copper content up to 10 mol %. It is found that the addition of CuO shifts the optical absorption edges towards lower energies in the range from 3.1 5-2.89 eV. The addition of CuO does not seem to introduce any new absorption band as compared with the spectrum of a pure vanadium phosphate glass. DSC measurements showed endothermal peaks varying from 475-510 ~ depending on the CuO content. 1. Introduction Measurement of the optical absorption coefficient, particularly near the fundamental absorption edge provides a standard method for the investigation of optically induced electronic transitions and provides some ideas about the band structure and energy gap in both crystalline and non-crystalline materials. Several transition metal oxides, when heated with glass-forming substances such as P205, TeO 2 and GeO2, form glasses on quenching from the melt. The loss of oxygen from the melt produces lower valency transition metal ions and indeed the electronic conduction in these glasses is associated with hopping of electrons from reduced to normal valency ions as discussed in detail by Mott [1]. A great deal of work has been carried out on many glass systems, including a number of semiconductor glasses based on the vanadium phosphate system [2-6]. During the last few years many workers have studied the oxide glasses containing mixed transition metal ions. Bogomolova et al. [7-9] have studied the PzOs-BaO-V205 CuO and PzOs-CaO-VzO5-CuO glasses and reported that a strong exchange inter- action exists between Cu 2+ and V 4+ ions, leading to the mixed exchange Cu 2+ and V ~+ pairs formation. Khan and Memon F10] studied the optical properties of vanadium phosphate glasses containing various amounts of VCf3 and found that the addition of chlorine acts asan oxidizing agent and alters the ratio of concentration of vanadium ions. Bandy0padhyay [11] investigated the BaO-B20 3 glasses containing single and mixed transition metal oxides and sug- gested that out of various types of interactions taking place in the system, strong interaction between V ~+ and Fe 3 + or Cu 2 + ions may result in the formation of V 4 +-O-Fe 3 + or V 4 +-O Cu 2 + associates. In this work we have studied the effect of the addition of cupric oxide on the optical and infrared absorption of vandium phosphate glasses. 2. Experimental procedure All glasses in the P205-V205-CuO system were pre- pared from analytical grade materials, according to their molar composition (Table I). The alumina cruc- ible containing the mixture was heated at 200 ~ for 1 h. This initial heating served to minimize material volatilization. The crucible was then transferred to a melting furnace maintained at a selected temperature of 1000 ~ for 2 h with frequent stirring. The homo- genized melts were then cast on a clean stainless steel plate mould (pre-heated to 250~ in the form of circular discs of 2 cm diameter and 2 mm thick. The disc was immediately transferred to another furnace which was already maintained at 300 ~ The furnace was kept at this temperature for 1 h and then was switched off to cool down to room temperature. The glass samples were polished using diamond paste down to a minimum grit size of 0.1 pro. X-ray diffrac- tion measurements confirmed the glassy nature of all samples used. For optical measurements, thin blown films of the glasses were prepared by dipping an alumina tube into the molten material and collecting a TABLE I Composition data for vanadium phosphate glasses containing cupric oxide Glass Composition Density sample (tool %) (g cm-3) (P205)50 (V2O5)50-(CuO)o 2.8134 (P205)50-(V205)47.5-(CuO)2.5 2.8428 (P205)5o (V2Os)45-(CuO)s 2.8710 (P205)5o-(V205)42.5-(CuO)7.5 2.890 (P2O 5)50-(V20 5)40-(Cu0) 10 2.9211 0022-2461 9 1992 Chapman & Hall 1343