Mossbauer study on the crystallization of IR-transmitting aluminate glasses

Heat treatment of 60CaO . 10BaO . 17Al(2)O(3). 13Fe(2)O(3) glass causes a precipitation of the nanoparticles of antiferromagnetic Ca2Fe2O5 and ferromagnetic BaFe2O4; Mossbauer spectra of these glass-ceramics show a magnetic relaxation spectra superimposed on doublets. A Kissinger plot in the DTA method reveals that simultaneous cleavage of Ca-O and Fe-O bonds and that of Ba-O and Fe-O bonds cause the precipitation of Ca2Fe2OS and BaFe2O4, respectively. Introduction of Fe(III) promotes the crystallization of aluminate glass. In the case of iron-free 60CaO . 10BaO . 30Al(2)O(3) glass, Ca2Al2O5 and BaAl2O4 particles precipitate instead of Ca2Fe2O5 and BaFe2O4 particles, respectively.