ࡱ> 9;8@ !bjbjFF .&,, fffzBBBB,nz   suuuuuu$R b9fk  kkok <fsks|f `OMBw_0zzf r) \    zzDzzINFLUENCE OF CRYSTALLIZATION ON THE ELECTRICAL CONDUCTIVITY OF IRON PHOSPHATE GLASSES V. Li ina1, A. Mogua-Milankovi1, }. Skoko2, S. T. Reis3, D. E. Day3 1Ruer Boakovi Institute, NMR Center, Bijeni ka c. 54, 10000 Zagreb, Croatia; e-mail  HYPERLINK "mailto:vlicna@irb.hr" Vesna.Licina@irb.hr 2Department of Physics, Faculty of Science, University of Zagreb, Bijeni ka c. 32, 10000 Zagreb, Croatia 3Graduate Center for Materials Research, University of Missouri-Rolla, Rola, MO 65409, USA Glass is by nature a meta-stable solid and tends to achieve the equilibrium by crystallization. This apparent disadvantage can be transformed into a positive point the nucleation and growth of the crystalline species is controlled, leading then to the new class of composite materials, called glass ceramics. It has been demonstrated that electrical properties of nano-phase materials are interesting because of specific size-related properties of crystalline domains or crystallites. The purpose of the present study is to investigate the crystallization of iron phosphate glasses and investigate the conduction mechanism before and after thermal treatment. The heat treatments were performed on the 40Fe2O3-60P2O5 (mol%) glass at 490, 590 and 650 C for 24 h. After each treatment the electrical conductivity was measured using impedance analyzer over wide frequency (0,1 Hz 3 MHz) and temperature range (303 - 473 K). The structure was analyzed by XRD. XRD structural analysis showed change of the structure from glassy to completely crystallized samples. The obtained lines in the XRD patterns correspond to the iron phosphate, FePO4, and iron pyrophosphate, Fe3(P2O7)2 structure. Glasses treated at 490 C (below Tg) showed nano-crystallization. By increasing temperature to 590 C (above Tg) the first crystalline phase, FePO4, was formed. With further increase second phase, Fe3(P2O7)2, started to crystallize. The impedance data are strongly affected by these structural changes. 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