Nanooptics and photonics 

Synthesis, morphology and optical properties of vanadate-borate glass-ceramics composites with luminescent nanoparticles
Chukova O.1,  Nedilko S.A.1,  Nedilko S.G.1, Voitenko T.1, , Manousaki A.2, Stratakis E.2 
1 Taras Shevchenko National University of Kyiv, Volodymyrska Str., 64/13, Kyiv 01601, Ukraine. E-mail: chukova@univ.kiev.ua
2 Institute of Electronic Structure & Laser (IESL) of Foundation for Research & Technology Hellas (FORTH), Heraklion 711 10 Crete, Greece.

Oxide micro/nanoscale glass ceramics composite materials are promising for the newest luminescent converting coatings for light emitting devices as they are characterized by high thermal and mechanical stabilities. Development of such glass composites in the present work deals with vanadate nanoparticles incorporated into borate-vanadate glass matrices. Vanadate compounds were chosen as crystalline component of the glass-ceramics with the aim to achieve the best interaction between activating nanoparticles with glass matrix and, at the same time, to achieve better optical transparency needed for some applications.
The vanadate-borate glass samples were synthesized by the melt quenching method. The glass compositions of the best optical characteristics were incorporated with luminescent La1-xEuxVO4:Ca vanadate nanoparticles. Simultaneous manifestations of both glass and crystalline components in the XRD patterns of the samples activated with vanadate nanoparticles have confirmed creation of vanadate-borate glass-ceramics materials. 
The band gap values dependencies on the components concentration were studied using Kubelko-Munk transformations. Luminescence properties of the made samples were measured in the wide spectral range. It was found that spectra of the doped with vanadate nanoparticles composites contain narrow spectral lines in the 580 -720 nm spectral range, those should be ascribed to well-known f-f electron transitions in the Eu3+ ions. Intensity of this emission depends on the way of luminescent nanoparticles incorporation into the glass. Influence of conditions of synthesis and optimal ratios of the components those allow obtaining of samples promising for practical applications as luminescent materials are discussed
The work has received funding from Ministry of Education and Science of Ukraine and from the Horizon Europe research  and innovation program within transnational access activity NFFA under grant agreement No 654360.