Magnetite-based glass-ceramics prepared by controlled crystallization of borosilicate glasses: Effect of nucleating agents on magnetic properties and relaxation. Issue 3 (15th February 2017)

• Record Type: Journal Article
• Authors: Sandu, V.; Cimpoiasu, E.; Greculeasa, S.; Kuncser, A.; Nicolescu, M.S.; Kuncser, V.
• Is Part Of: Ceramics international. Volume 43:Issue 3(2017)
• Page Start: 3405
• Page End: 3413
• Publication Date: 2017-02-15
• Subjects: Magnetite -- Glass ceramics -- Mössbauer spectroscopy -- Ac susceptibility -- Magnetic relaxation -- Superparamagnetism; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2016.11.188
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: The specific magnetic structure and magnetic relaxation phenomena in magnetite nanoentities grown in a glassy matrix by controlled crystallization of Fe-containing borosilicate and boroaluminosilicate glasses in the presence of two types of nucleating agents, Cr2 O3 and P2 O5, were investigated. The structure, morphology and magnetic properties are strongly influenced by the nucleating agents. Cr2 O3 generates magnetite-based glass ceramics with magnetite configurations showing an upward relaxation of magnetization at low and high temperatures but downward at intermediate temperatures. The magnetite grown with P2 O5 displays only downward relaxation but with different signs of the temperature derivative of the relaxation rate S in different temperature ranges. The observed effects are discussed with respect to the following factors: i ) the existence of a multimodal size distribution of the magnetite (nano)particles as revealed by high resolution electron microscopy; ii ) the degree of occupation of different sublattices of the magnetite structure with Fe 3+ and Fe 2+ ions; and iii ) the interplay between the relaxation mechanisms in different temperature ranges.