Nanooptics and photonics 

Structure, morphology and spectroscopy studies of La1-xSmxVO4 nanoparticles synthesized by two various methods
Chukova O.V. 1,  Moroz I.V.1,  Nedilko S.A.1,  Nedilko S.G.1, Slepets A.A.1,  Scherbatskiy V.P.1, Voitenko T.A.1, Papadopoulos A.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.

Wide range of applications have attracted significant research efforts to development of new vanadate materials and compositions with improved characteristics depending on requirements of various practical tasks. Recently, studying the Eu3+-activated LaVO4 vanadate nanoparticles, we have achieved increase of emission intensity in 10 times using various synthesis conditions. The best intensity characteristics were obtained for the La1-xEuxVO4 nanoparticles synthesized by sol-gel method. In order to continue this study, in the present work we investigate properties of Sm-activated LaVO4 vanadate nanoparticles synthesized by two methods. There are sol-gel and co-precipitation methods. 
The main attention is paid to detailed spectroscopy investigation of luminescent properties of the Sm3+ ions as possible instrument for clear understanding of structure and origins of their emission centers in the studied matrix. Emission spectra of the Sm3+ ions are observed in the 550 – 700 nm range. Excitation spectra consist of the main band in 250 – 350 nm spectral range with maxima at 320 nm and three groups of more narrow and structured spectral components in 350 – 520 nm spectral range. It is found that number and positions of spectral peaks in absorption, reflection, emission, and excitation spectra of the synthesized samples depend on method of synthesis. 
Spectral properties are discussed together with analysis of XRD, SEM and IR absorption data. The conclusion is made about relations of method of synthesis with crystal phase compositions of the obtained nanoparticles and about its effects on structure of the spectra of the Sm3+ ions in the investigated samples.
This  project  has  received  funding  from  Ministry of Education and Science of Ukraine and from the  EU-H2020  research  and innovation program  under  grant  agreement  No  654360  having  benefited  from  the access  provided  by Institute of Electronic Structure & Laser (IESL) of Foundation for Research & Technology Hellas (FORTH) in Heraklion, Crete, Greece within  the  framework  of  the  NFFA-Europe Transnational  Access Activity.