Patra, Pritha (2025) Exploration of Thermal, Structural and Spectroscopic Properties of IR-Transmitting Glasses and Glass-Ceramics for Advanced Photonic Applications. PhD thesis, AcSIR.

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Abstract

This thesis work is devoted to develop a series of novel tellurite glass compositions that will aid fabrication of highly transparent glass-ceramics with exotic properties suitable for broadband NIR/MIR emission and optical limiting. Three rare-earth (RE) containing tellurite glass series, (i) 5La2O3-5RE2O3-10TiO2-80TeO2, (ii) 75TeO2-10TiO2-7(Y/Lu)2O3-3La2O3- 5Al2O3, (iii) 10REF3-10TiO2-80TeO2 are prepared. Glass-ceramics fabricated from these compositions are embedded with RE containing “anti-glass” Ln2Te6O15 crystallites. Hence, it is important to find out the effect of dopant RE3+ ionic radii and their concentration in retaining the transparency of glass-ceramics. The studies revealed that RE “hole-pair” ions with 4fn and 4f14-n electronic configuration exhibit identical crystal growth mechanism followed by identical transparency retention in the fabricated glass-ceramics of 2RE2O3-3La2O3-5Gd2O3-10TiO2- 80TeO2 glass series (RE= Ce-Dy). The transparency of the glass-ceramics is found to be improved with the dopant ion concentration in xNd2O3-(5-x)La2O3-5Gd2O3-10TiO2-80TeO2 glass, x=0.5-2 mol%. Utilizing Eu3+ as a structural probe it is revealed that the local structure of “anti-glass” Ln2Te6O15 crystallites is glass like C2 or C2v symmetry in these glass-ceramics. Also, Eu3+ doped transparent glass-ceramics shows great potential to be used as red component of WLED. Further, in the second glass series the inclusion of Al2O3 in appropriate proportion has not only improved their thermal stability and mechanical strength, but also provided more control over crystallization leading to formation of ultra-transparent glass-ceramics from 75TeO2-10TiO2-7(Y/Lu)2O3-3La2O3-5Al2O3 glass. Broadband 3 μm emission with effective bandwidth (Δλeff) ~400 nm is attained from Er/Yb/Ho/Dy co-doped ultra-transparent glassceramics indicating its suitability for tunable MIR laser gain. It has been observed from third glass series fluorine incorporation in the composition aids decrease in phonon energy of the matrix, which has directly reflected from improved 1.8 μm emission and decay time of Tm3+ ion under 475 nm excitation. The measured third-order non-linearity of lanthanide-Tellurite glass and glass-ceramics demonstrates that non-luminescent REs: La, Gd, Lu, and Y play significant role in optical non-linearity. In case of glass, cubic hyperpolarizability of REs, while in glass-ceramics their quadratic hyperpolarizability is found dominant. Fabricated glassceramics exhibit lowest limiting threshold value ~5 mJ/cm2 (manyfold lower than reported glass/glass-ceramics). Further, using Nd3+ as a dopant much lower limiting threshold value of ~4 mJ/cm2 is achieved due to resonant non-linearity. Prepared TeNps@TeO2 glass composite exhibit interesting non-linear properties and lowest limiting threshold of 3.65 mJ/cm2 . Large non-linear co-efficient and low limiting threshold value compared to existing non-linear optical materials suggest present matrices can be a suitable candidate for optical limiting and Kerr induced self-focusing.

Item Type:	Thesis (PhD)
Additional Information:	Supervisor: Dr K Annapurna, CGCRI
Subjects:	Glass
Divisions:	Glass
Depositing User:	Ms Upasana Sahu
Date Deposited:	12 Nov 2026 12:07
Last Modified:	12 Nov 2026 12:07
URI:	https://cgcri.csircentral.net/id/eprint/5852

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