المؤلفون: Roberto Lorenzi, Nikita V Golubev, Elena S. Ignat’eva, Vladimir N Sigaev, Silvia Trabattoni, Adele Sassella, Alberto Paleari

المساهمون: Lorenzi, R, V Golubev, N, Ignat’Eva, E, N Sigaev, V, Trabattoni, S, Sassella, A, Paleari, A

مصطلحات موضوعية: The ability to growth crystalline nanostructures in amorphous glass is a successfully strategy for the design of novel functional and structural materials. On the one hand, the oxide matrix ensures ideal workability, chemical inertness, and mechanical robustness. On the other hand, crystalline nanoparticles may give rise to unprecedented electrical, mechanical, or optical functionalities. In the latter field, alkali germano-silicate glasses containing gallium oxide spinel nanoparticles, prepared by the melt-quenched method, represent an interesting solution as multipurpose photonic materials. In fact, the low refractive mismatch between crystals and matrix as well as the ability of obtaining nanostructures with dimensions of the order of few nanometers enables the possibility of having a transparent material with peculiar optical properties. The nanophase, mainly LiGa5O8 and γ-Ga2O3, are wide-bandgap semiconductors (EG = 4.9 eV) showing strong blue luminescence upon excitation at wavelength shorter than 280 nm and related to recombination at donor and acceptor pairs.1 For these reasons Ga2O3-based materials would be particularly suitable, in principle, for the fabrication of simple and robust UV-to-visible converters. A typical composition of these type of materials is 7.5 Li2O − 2.5 Na2O – 20 Ga2O3 – 45 GeO2 – 25 SiO2 %mol. Initially, a fully amorphous glass is prepared by melting at 1480 °C for about 40 min and rapid quenching at room temperature. The as-quenched bulk samples undergo to a prolonged nucleation pre-treatment for 18 h at temperatures close to the glass transition (≈ 560 °C) and finally treated at the crystallization temperature at ≈ 650 °C for 30 min.2 Here we present our results on the optimization of the intrinsic emission features through fine control of thermally induced changes of spinel nanocrystals in glass. We will focus on the role of diffusion and coalescence mechanisms in the phase changes of Ga-oxide nanophases and a comparison of the structural evolution of Ga2O3 nanopowder and Ga2O3 nanophase in glass. Finally, we will discuss the possibility of obtaining thin films by radio-frequency sputtering of targets made of the investigated glass.3 Interestingly, the films show the appearance of lenticular nanostructures ascribable to Ga2O3 segregation, as confirmed by several different scattering techniques – including X-ray diffraction, X-ray reflectivity, small-angle X-ray scattering –, as well as, atomic force and electron microscopy.

Relation: ispartofbook:Italian Crystal Growth 2021; Italian Crystal Growth 2021; firstpage:19; lastpage:20; numberofpages:2; http://hdl.handle.net/10281/341374

الاتاحة: http://hdl.handle.net/10281/341374