Saikia Chaliha, Reenamoni and Annapurna, K and Tarafder, Anal and Tiwari, V S and Gupta, P K and Karmakar, Basudeb (2010) Optical and dielectric properties of isothermally crystallized nano-KNbO(3) in Er(3+)-doped K(2)O-Nb(2)O(5)-SiO(2) glasses. Spectrochimica Acta Part A-Molecular and Biomolecular Spectroscopy, 75 (1). pp. 243-250. ISSN 1386-1425

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Abstract

Precursor glass of composition 25K(2)O-25Nb(2)O(5)-50SiO(2) (mol%) doped with Er(2)O(3) (0.5wt% in excess) was isothermally crystallized at 800 degrees C for 0-100h to obtain transparent KNbO(3) nanostructured glass-ceramics. XRD, FESEM, TEM, FTIRRS, dielectric constant, refractive index, absorption and fluorescence measurements were carried out to analyze the morphology, dielectric, structure and optical properties of the glass-ceramics. The crystallite size of KNbO(3) estimated from XRD and TEM is found to vary in the range 7-23 nm. A steep rise in the dielectric constant of glass-ceramics with heat-treatment time reveals the formation of ferroelectric nanocrystalline KNbO(3) phase. The measured visible photoluminescence spectra have exhibited green emission transitions of (2)H(11/2). (4)S(3/2) -> (4)I(15/2) upon ;excitation at 377 nm ((4)[(15/2) -> (4)G(11/2)) absorption band of Er(3+) ions. The near infrared (NIR) emission transition (4)[(13/2) -> 4[(15/2) is detected around 1550 nm on excitation at 980 mn ((4)[(15/2) -> 4 [(11/2)) of absorption bands of Er(3+) ions. It is observed that photoluminescent intensity at 526 nm ((2)H(11/2) -> (4)I(15/2)), 550nm (4S(3/2) -> (4)I(15/2)) and 1550nm ((4)I(13/2) -> (4)I(15/2)) initially decrease and then gradually increase with increase in heat-treatment time.'rhe measured lifetime (tau(f)) of the (4)I(13/2) -> (4)I(15/2) transition also possesses a similar trend. The measured absorption and fluorescence spectra reveal that the Er(3+) ions gradually enter into the KNbO(3) nanocrystals. (C) 2009 Elsevier B.V. All rights reserved.

Item Type:	Article
Uncontrolled Keywords:	Transparent glass-ceramic; Nanocrystallized Er(3+):KNbO(3); Luminescence; Ferroelectric crystals; Dielectric constant
Subjects:	Glass
Divisions:	Glass
Depositing User:	Bidhan Chaudhuri
Date Deposited:	09 Feb 2012 07:58
Last Modified:	17 Apr 2012 10:10
URI:	http://cgcri.csircentral.net/id/eprint/630

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