A. Nadiri

Electronic and ionic conductivity of glasses inside the Li2O–MoO3–P2O5 system

Abstract A wide range of coloured electronic or mixed electronic–ionic glasses has been shown in the alkali oxide poor-region of the Li 2 O–MoO 3 –P 2 O 5 system, next to the colourless ionic glasses located in the alkali oxide rich-region. These coloured glasses have been studied by electron paramagnetic resonance (EPR) spectroscopy. The Mo 5+ and Mo 6+ cation percentages have been evaluated for several series of glasses corresponding to either a fixed Li 2 O rate or a constant Mo/P ratio. The electronic and the ionic contributions to the total conductivity of these glasses have been determined. The existence of a polaronic hopping conduction mechanism between Mo 5+ and Mo 6+ cations is suggested in the purely electronic conductor glasses. An ion–polaron soft coupling is proposed in the ionic–electronic conductor glasses.

Electrical properties of glasses in the Na2O–MoO3–P2O5 system

Abstract A range of coloured electronic or mixed ionic–electronic glasses has been evidenced in the Na 2 O–MoO 3 –P 2 O 5 system. The properties of these glasses have been studied along different composition lines corresponding either to a fixed Na 2 O content or a constant Mo/P ratio. An EPR spectroscopy investigation of these glasses has allowed to determine the Mo 5+ ion percentages in these materials. The electrical properties of these glasses have been studied by impedance spectroscopy, and the electronic and ionic contributions have been evaluated. The properties of these sodium glasses have been compared with those of lithium glasses with the same compositions.

Partial enthalpies of titanium, hafnium, tantalum, tungsten and iridium in liquid tin at high dilution

Abstract The partial enthalpies of titanium, hafnium, tantalum, tungsten and iridium in liquid tin at 1173K were measured at high dilution by direct reaction calorimetry (drop method) with the help of a Tian-Calvet high-temperature calorimeter. When referred to liquid metals we found h Ti /kJ.mol −1 =106.3−25.6 x Ir , h Hf / kJ.mol −1 =87.3+29.1 x Hf , h Ta / kJ.mol −1 =102.7−9.6 x Ta , h W /kJ.mol −1 =94.9−58.2 x W and h Ir /kJ.mol −1 =−111.2−12.4 x Ir . The limiting partial enthalpies were deduced by extrapolation to infinite dilution.

Calorimetric investigation of the solid compounds of the Au–Pb system

Abstract The three intermediate compounds of the Au–Pb system were synthesised by melting the pure components in suitable proportions and annealing at a temperature just below their melting point. Their structural states were verified by X-ray studies. The enthalpy of formation of the compounds was measured by dissolution calorimetry (drop method) at 650K in liquid lead using a high temperature Tian–Calvet calorimeter. The measurements lead to: h f ( Au 0.667 Pb 0.333 , cr , 298 K )=−3.1 kJ mol −1 h f ( Au 0.333 Pb 0.667 , cr , 298 K )=−3.2 kJ mol −1 h f ( Au 0.25 Pb 0.75 , cr , 298 K )=−1.6 kJ mol −1