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Samarium doped LaYO3 nanocrystalline phosphor powders are obtained by polymer complex solution method. Stoichiometric quantities of La2O3, Y2O3 and for dopant ions Sm2O3 were dissolved in hot nitric acid. Polyethylene glycol was added in solutions in 1:1 mass ratio to corresponding metal nitrates to form gel. The gel is combusted and annealed at 800 °C for two hours to form nanopowder samples. Crystalline structure and phase purity is checked by X-ray diffraction and show that this material is synthesized in cubic bixbyite type structure for the first time. Luminescence properties of Sm3+ doped LaYO3 exhibited characteristic orange-red emission coming from the intra-4f-shell 4G5-2→6HJ electron transitions with emission decay of 1.5 ms. Energy level positions are derived from emission and excitation spectra. [ABSTRACT FROM AUTHOR]

We prepared Eu3+- and Sm3+-doped YNbO4 phosphor powders using a simple solid-state reaction method and examined their photoluminescence properties in order to investigate the possibility for their usage in phosphor thermometry. Photoluminescence measurements were performed in the temperature range 303–773K, and the fluorescence intensity ratio of the paired emissions lines was studied as a function of temperature. The results have shown that YNbO4:Eu3+ possesses the absolute sensitivity of approximately 3Ã?10−3 K−1 at about 700K, while relative sensitivity changes within the range of 0.5–2.7%K−1. YNbO4:Sm3+ has the maximum sensitivity of around 7Ã?10−4 K−1 at about 700K with the relative sensitivity of 0.43%K−1 around 500K. Calculated temperature sensitivities of samples show that these materials have a good potential for the development of thermographic phosphors. Experimental lifetime measurements recorded at 303–773K were fitted using a temperature dependent charge transfer model, TDCT. This model yields good agreement between experimental and fitted lifetime data. The sample crystalline structure is confirmed by XRD measurements. [ABSTRACT FROM AUTHOR]

Abstract: In this research we prepared nanocrystalline YNbO4:Eu3+ phosphor, i.e. nanophosphor, powder using an efficient mechanochemical method followed by annealing. X-ray diffraction analysis revealed that YNbO4:Eu3+ crystallizes in monoclinic structure C2/c where, from the point of view of A and B in ABO4 compounds, cation coordination can be noted as [6+2, 4+2]. Crystallite size of about 40nm, was estimated using Debye Scherrer's equation. Raman spectroscopy with 785 and 532nm excitation wavelengths is performed to record a majority of materials phonon modes and to provide more in depth understanding of the YNbO4 structure. Scanning electron microscopy observations indicate that the mechanical treatment during synthesis is causing non-uniformity of the powder microstructure. High resolution photoluminescent measurements upon UV excitation showed intense emission coming from f–f transitions of the europium ion with the lifetime of 0.68ms, suggesting that the obtained YNbO4:Eu3+ is a good potential phosphor. A comparison of emissive properties with microcrystalline YNbO4:Eu3+ was made and it showed higher values of emission intensity and lifetime of the nanocrystalline sample. [Copyright &y& Elsevier]

Abstract: We prepared an efficient YNbO4:Eu3+ phosphor using a simple solid-state reaction method and examined its photoluminescent properties in order to investigate the possibility for its usage in phosphor thermometry. Photoluminescence measurements were performed in the temperature range 303–803 K, and the fluorescence intensity ratio (FIR) of the paired emissions lines of Eu3+ (5D1 → 7F1 and 5D0 → 7F1 transitions) was studied as a function of temperature. The sample crystalline structure is confirmed by XRD measurements. The material is proved to have a good potential for the development of thermographic phosphors. It exhibits maximum temperature sensitivity of approximately 3.5 × 10−3 K−1 in the temperature region around 700 K. [Copyright &y& Elsevier]