Center for Materials Engineering

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Browsing Center for Materials Engineering by Author "Hailu, Redae"

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    Synthesis of High Refractive Index La3+ Doped BaTiO3 Nanoparticles for Retroreflective Application Via Water Assisted Solid State Reaction
    (Addis Ababa University, 2019-06) Hailu, Redae; Sintayehu, Nibret (PhD)
    To guarantee the safe and well-organized movement of traffic on highway during bad weather and nighttime conditions, traffic signs, markings, helmet and safety textile paints have to be illuminated and made of retro-reflective materials. Materials having collective fluorescent and retro-reflective properties importantly improve visibility. For production of these materials Ceramics of glass having high refractive index are used. Most ceramic materials for different applications are synthesized by a conventional solid state reaction (SSR) method. In solid state reaction ionic diffusion in an ionic crystal is very sluggish at about room temperature Therefore it needs a high temperature conditions for boosting the reactivity between raw materials. Liquid phase reaction also can arise at relatively low temperature to SSR but needs additional temperature to dry the solvent and superior equipment for separation. Methods currently used to synthesis glass beads such as Container less flamespray, Conventional SSR, Molten salt etc. requires high temperature (780 ºC-1300ºC) to synthesize high purity glass beads. Furthermore, products obtained using these methods have large bead/ powder sizes. activated BaTiO3 at 100ºc. The starting materials, La2O3, TiO2, and Ba(OH)2.8H2O, weighed according to the stoichiometric ratio and mixed for 15 minutes with 8% of deionized water, Store in an automatic Oven for 6 hours at 100ºc. The La doping level were 0%, 5% and 10%. In this study, a WASSR route is employed to synthesize nano-sized La 3+ X-ray diffraction of the as prepared new material confirmed the product has a structure of Tetragonal BaTiO3 having a size ranging from 19.39 to 21.64nm.EDS mapping of the as prepared sample showed uniform distribution of components. From UV-Vi spectrometry, the La 3+ activated BaTiO3 nanoparticles has shown a refractive index of 3.392 when La doping was 1%. Raman spectroscopy also confirmed the structure of the as prepared sample is Tetragonal. The refractive index of nanoparticles greatly increased the wide wavelength range (426–900 nm), which is very useful for some special surfaces that require illumination from reflection of light rays, such as protective reflective helmet or clothes, road side signs, etc. In addition, it can be used as heat reflective layer, which solves the urban heat island effect.