Mid‐IR transparent TeO 2 ‐TiO 2 ‐La 2 O 3 glass and its crystallization behavior for photonic applications

In this report, effect of enhanced rare earth (La 2 O 3 ) concentration on substitution of TeO 2 within ternary TeO 2 ‐TiO 2 ‐La 2 O 3 (TTL) glass system has been studied with respect to its thermal, structural, mechanical, optical, and crystallization properties with an aim to achieve glass and glass‐ceramics having rare‐earth‐rich crystalline phase for nonlinear optical and infrared photonic applications. DSC analysis (10°C/min) demonstrates a progressive increase in glass‐transition temperature ( T g ) from 359 to 452°C with the increase in La 2 O 3 content. Continuous glass network modification with transformation of [TeO 4 ] to [TeO 3 /TeO 3+1 ] units is evidenced from Raman spectra which is corroborated with XPS studies. While mechanical properties demonstrate enhancement of cross‐linking density in the network. These glasses exhibit optical transmission window extended from 0.4 to 6 μm with calculated zero dispersion wavelength (λ ZDW ) varying from 2.41 to 2.28 μm depending upon La 2 O 3 content. Crystallization kinetics of TTL10 (80TeO 2 ‐10TiO 2 ‐10La 2 O 3 in mol%) glass has been studied via established models. Activation energy ( E a ) has been evaluated and dimensionality of crystal growth ( m ) suggests formation of surface crystals. Glass‐ceramic with crystalline phase of La 2 Te 6 O 15 has been realized in heat‐treated TTL10 glass samples (at 450°C). As predicted from DSC analysis, FESEM study unveils the formation of surface crystallized glass‐ceramics.