title: Enhanced up-conversion and temperature-sensing behaviour of Er(3+) and Yb(3+) co-doped Y2Ti2O7 by incorporation of Li(+) ions.
abstract: Y2Ti2O7:Er(3+)/Yb(3+) (EYYTO) phosphors co-doped with Li(+) ions were synthesized by a conventional solid-state ceramic method. X-ray diffraction studies show that all the Li(+) co-doped EYYTO samples are highly crystalline in nature with pyrochlore face centred cubic structure. X-ray photon spectroscopy studies reveal that the incorporation of Li(+) ions creates the defects and/or vacancies associated with the sample surface. The effect of Li(+) ions on the photoluminescence up-conversion intensity of EYYTO was studied in detail. The up-conversion study under ∼976 nm excitation for different concentrations of Li(+) ions showed that the green and red band intensities were significantly enhanced. The 2 at% Li(+) ion co-doped EYYTO samples showed nearly 15- and 8-fold enhancements in green and red band up-converted intensities compared to Li(+) ion free EYYTO. The process involved in the up-conversion emission was evaluated in detail by pump power dependence, the energy level diagram, and decay analysis. The incorporation of Li(+) ions modified the crystal field around the Er(3+) ions, thus improving the up-conversion intensity. To investigate the sensing application of the synthesized phosphor materials, temperature-sensing performance was evaluated using the fluorescence intensity ratio technique. Appreciable temperature sensitivity was obtained using the synthesized phosphor material, indicating its applicability as a high-temperature-sensing probe. The maximum sensitivity was found to be 0.0067 K(-1) at 363 K.
authors.affiliation: Department of Physics, Indian Institute of Technology (BHU), Varanasi, India-221005.
authors.forename: B P
authors.initials: BP
authors.lastname: Singh
authors.forename: A K
authors.initials: AK
authors.lastname: Parchur
authors.forename: R S
authors.initials: RS
authors.lastname: Ningthoujam
authors.forename: P V
authors.initials: PV
authors.lastname: Ramakrishna
authors.forename: S
authors.initials: S
authors.lastname: Singh
authors.forename: P
authors.initials: P
authors.lastname: Singh
authors.forename: S B
authors.initials: SB
authors.lastname: Rai
authors.forename: R
authors.initials: R
authors.lastname: Maalej
mesh_terms: D004735:Energy Transfer; D004871:Erbium / Q000737:chemistry*; D007477:Ions; D008094:Lithium / Q000737:chemistry*; D008163:Luminescent Measurements; D013059:Spectrum Analysis, Raman; D013696:Temperature; D014025:Titanium / Q000737:chemistry*; D015018:Ytterbium / Q000737:chemistry*
chemical_list: D007477:Ions; C009495:titanium dioxide; D004871:Erbium; D008094:Lithium; D014025:Titanium; D015018:Ytterbium