resumo
Magnesium aluminosilicate glasses were proposed as molten electrolyte for iron pyroelectrolysis, an alternative electrometallurgical technique offering environmental and economic advantages over traditional steelmaking. This work focuses on mechanisms of iron incorporation in the glass network and related effects on physical properties. The study was performed on amorphous Fe-containing glass fibres, grown by laser floating zone in strongly non-equilibrium conditions, to retain frozen-in states characteristic for glass electrolyte at high temperatures. Up to 4 mol% content the iron cations possess predominantly 2+ oxidation state, act mostly as a network modifier and are distributed as isolated ions in the glass network. Presence of magnetic exchange interactions and paramagnetic resonance signal at g similar to 2.0 in the case of higher iron contents suggest progressive clustering of iron cations. The observed clustering and concomitant increase in the electrical conductivity indicate possible appearance of redox-driven hopping conductivity, acting as an electronic contribution to charge transport. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
palavras-chave
SODIUM-SILICATE GLASSES; MOSSBAUER-SPECTROSCOPY; MELTS; OXIDATION; COORDINATION; TEMPERATURE; SYSTEM; METAL
categoria
Materials Science
autores
Ferreira, NM; Kovalevsky, AV; Valente, MA; Sobolev, NA; Waerenborgh, JC; Costa, FM; Frade, JR
nossos autores
Andrei Kavaleuski
Investigador principal
Jorge Ribeiro Frade
Professor(a) Jubilado(a)
Nuno Miguel Freitas Ferreira
Bolseiro de pós-DoutoramentoProjectos
IERO-Iron production by Electrochemical Reduction of its Oxide for high CO2 mitigation (IERO)
agradecimentos
Research leading to these results has received support from European Union Research Fund for Coal and Steel (RFCS) research program, under Grant agreement RFSR-CT-2010-00002, and by FEDER Funds through the COMPETE 2020 Programme and National Funds through FCT-Portuguese Foundation for Science and Technology under the projects UID/CTM/50025/2013, FCT Investigator 2012 program - Grant IF/00302/2012 and UID/CTM/50011/2013. N.A.S. acknowledges support from NUST