The thermal properties (expansion, Tg and TSOFT.) of glasses, having 56–66% P2O5, 14.8–34.2% Fe2O3 and 2–25 wt% additions of SiO2, Al2O3, Na2O and UO2, were comparatively estimated from dilatometric measurements in similar conditions. The Tg reversibility was clearly verified by varying the heating rates between 1 and 5 °C min−1. From linear equations fits of the various glass properties as functions of the six components it is suggested the iron, sodium and uranium oxides decrease the thermal expansion (for 50 < T ⩽ 300 °C), Tg andTSOFT. From DTA/XRD analysis of three glasses it was confirmed the crystallization tendency decreased with increasing the UO2 level in the glasses. Leaching test data for two compositions containing Na2O suggest addition of UO2 increases the chemical durability of the related glass. The roles of UO2, Na2O and Fe-oxide species as structural components of the glass network are discussed.

The authors thank Messrs C. Cotaro, E. Scerbo and J. Menghini [Centro Atómico Bariloche] for the EDS/Edax analysis and leaching tests; Messrs. M. Sanfilippo and A. Heredia for their help in sample preparation; and Dr R.D. Pérez (CEPROCOR, Córdoba) for the X-rays fluorescence analysis. The financial support of the Centro Atómico Bariloche Superconductivity Group, which allowed the purchase of the main parts of the dilatometer is acknowledged. Financial help of J. Ma. Rincón for stage at CAB supported by IAEA, Viena, is much appreciated as well as the financial support of Univ. Nac. de Cuyo and C.O.N.I.C.E.T.

This work is dedicated to the memory of Professor Peter Finlay James, who deceased on 2nd July, 2005.

Peer reviewed