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Gd2O3:Er3+ nanophosphors were fabricated by the combustion method in presence of Na2 ethylene diamine tetra acetic acid (EDTA-Na2) as fuel at not high temperature (≤350 oC) within a very short time of 5 min. The added concentration of Er3+ ions in Gd2O3 matrix was changed from 0.5 mol% to 5.0 mol%. The X-ray diffraction pattern of samples indicates the monoclinic structure of Gd2O3:Er3+. The morphology and chemical composition analysis of the Gd2O3:Er3+ samples are characterized by a field emission scanning electron microscope (FESEM) and a Fourier-transform infrared spectrometer (FTIR). The photoluminescence (PL), photoluminescence excitation (PLE) and upconversion (UC) at room temperature of the prepared materials with different concentrations of Er3+ were investigated. The PL of Gd2O3:Er3+ nanomaterials are shown in visible at 545, 594, 623, 648, 688 nm under excitation at 275 nm. The emission bands from transitions of Er3+ from 2P3/2 to 4F9/2 are observed. UC luminescent spectra of the Gd2O3:Er3+/silica nanocomposites under 976 nm excitation show the bands at 548 and 670 nm. The influence of excitation power at 980 nm for transitions were measured and calculated. The results indicate that the upconversion process of Gd2O3:Er3+/silica is two photons absorption mechanism. The low temperature dependence of UC luminescent intensities of the main bands of Gd2O3:Er3+ was investigated towards development of a nanotemperature sensor in the range of 10–300 K.

In this paper, the experimental parameters that control the monodisperse and high quality Gd2O3:Eu3+ and Gd2O3:Eu3+@silica nanospheres (NSPs) systematically investigated. Gd2O3:Eu3+ and Gd2O3:Eu3+@silica NSPs in size range from 100 to 200 nm with a very low standard size deviation of ±5.00% have been successfully fabricated. The luminescence spectra of Gd2O3:X%Eu3+ and Gd2O3:X%Eu3+@silica NSPs were studied as a functions of Eu3+ ion concentration (X = 3.50; 5.00; 6.00; 7.00; 7.50 and 8.00 at.%). The strongest emission peak at 611 nm corresponding to 5D0–7F2 transition of Eu3+ ions in Gd2O3:Eu3+ NSPs was very sharp. Interestingly, for the silica coated Gd2O3:X%Eu3+ NSPs, a new emission peak at 621 nm was appeared in depend on the coating condition. The intensity ratio of the emission peaks at 611 nm and 621 nm was decreased with the increase of the silica thickness. The highly monodispersed, mesoscaled Gd2O3:Eu3+ and Gd2O3:Eu3+@silica NSPs synthesized in this work are high potential for application, especially in photonic crystals, bioimaging and drug delivery.

In this report, we are presenting the controlled fabrication results of the strong emission YVO 4 : Eu 3+ nanoparticles and nanowires by microwave which is assisted chemical synthesis. The effects of incorporated synthesis conditions such as microwave irradiated powers, pH values and concentration of chemical composition on properties of nanomaterials are also investigated to obtain the controllable size and homogenous morphology. Morphological and optical properties of YVO 4 : Eu 3+ prepared products which have been characterized by X-ray diffraction (XRD), field emission micrcroscopy (FESEM) and photoluminescence spectroscopy. As based from result of synthesized samples, we found that the changing of pH values, microwave irradiated powers and chemical composition rise to change reform the size and shape of materials from nanoparticles (diameter about 20 nm) to wires shape (with about 500÷800 nm length and 10÷20 nm width). The photoluminescence (PL) spectroscopy measurements of YVO 4 : Eu 3+ nanostructure materials under UV excitation showed that: the strong luminescence in red region with narrow lines corresponding to the intra-4f transitions of 5 D 0 – 7 F j ( j =1, 2, 3, and 4) of Eu 3+ ions with the highest luminescence intensity of 5 D 0 → 7 F 2 transition.

Fabrication and characterization of YVO 4 :Eu 3+ nanophosphors prepared by microwave (MW) irradiation assisted soft template synthesis were reported. The effects of synthesis conditions such as different powers of MW irradiation, pH values and concentration of reaction materials on properties of nanophosphor were also investigated to obtain the controllable size, morphology and high luminescence efficiency. Morphology, crystalline structure, and optical properties were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and fluorescence spectroscopy, respectively. The results showed that YVO 4 :Eu 3+ nanophosphors were obtained by using diethyleneglycol (DEG) as soft template, with pH values in the range of 4 to 12, upon microwave irradiation from 300 to 900 W, at temperature of 80 °C. The high fluorescent YVO 4 :Eu 3+ nanocrystals obtained with size from 15 nm down to 8 nm are more effective to develop an ultrahigh sensitive fluorescent label for biomolecule, cell and tissue.