Molla, Atiar Rahaman and Chakradhar, R P S and Kesavulu, C R and Rao, J L and Biswas, S K (2012) Microstructure, mechanical, EPR and optical properties of lithium disilicate glasses and glass-ceramics doped with Mn2+ ions. Journal of Alloys and Compounds, 512 (1). pp. 105-114. ISSN 0925-8388

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Abstract

The microstructure, mechanical, EPR and optical properties of transparent MnO2 doped lithium disilicate (LDS) glass-ceramics prepared by melt quenching and controlled crystallization, have been studied. The microstructure of the glass-ceramics has been characterized using FE-SEM, TEM, FT-IR and XRD techniques. FE-SEM micrographs show elongated, highly interlocked, dense (similar to 80 vol.%) nanocrystals of LDS with an average size similar to 100 nm. XRD and FT-IR studies reveal that the only crystalline phase formed after heat-treatment at 700 degrees C for 1 h is LDS. A good combination of average microhardness similar to 5.6 GPa, high fracture toughness similar to 2.8 MPa m(1/2), 3-point flexural strength similar to 250 MPa and moderate elastic modulus 65 GPa has been obtained. The EPR spectra of both LDS glasses and glass-ceramics exhibit resonance signals with effective g values at g = 4.73, g = 4.10, g = 3.3, and g = 1.98. The resonance signal at g = 1.98 is found to be more intense than the other signals and exhibits hyperfine structure at lower concentration of manganese. From the observed spectrum, the spin-Hamiltonian parameters have been evaluated. In glass samples the optical absorption spectrum exhibits a broad band around similar to 20,320 cm(-1) which has been assigned to the transition (6)A(1g)(S) -> (4)A(1g)(G) (4)Eg(G)-of Mn2+ ions. The cerammed samples upon 394 nm excitation emit a green luminescence (565 nm, (4)T(1)g -> (6)A(1g)(G) transition of Mn2+ ions), and a weak red emission (710 nm). From the ultraviolet absorption edges, the optical bandgap energies (E-opt) were evaluated and are discussed. (C) 2011 Elsevier B. V. All rights reserved.

Item Type:	Article
Uncontrolled Keywords:	Glass; Glass-ceramics; Microstructure; EPR; Optical; Mechanical properties
Subjects:	Glass
Divisions:	Glass
Depositing User:	Bidhan Chaudhuri
Date Deposited:	04 Jun 2012 08:07
Last Modified:	04 Jun 2012 08:07
URI:	http://cgcri.csircentral.net/id/eprint/1458

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