title: Synthesis and spectroscopic properties of GdAl3(BO3)4 poly-crystals codoped with Yb3+ and Eu3+.
abstract: GdAl3(BO3)4 polycrystals co-doped with Yb3+ and Eu3+ has been synthesised by combustion method with urea. Upon the excitation at 465 nm (Eu3+/7F6-->5D2 transition), emission bands centered at 590, 613, 697 and 702 nm in the wavelength region of 550-750 nm have clearly been observed, assigned to the electronic transitions of 5D0-->7FJ (J=1, 2, 4 and 5) of Eu3+ ions, respectively. Meanwhile, an intense emission centred at 980 nm along with a shoulder at 1,040 nm has also been observed by exploiting a cross-relaxation process between the transitions of Eu3+/5D0-->7F6 and Yb3+/2F7/2-->2F5/2. On the contrary, an intense red up-conversion emission centred at 613 nm originated from the 5D0-->7F2 transition of Eu3+ has been observed upon excitation with 980 nm laser diode. The quadratic dependence of the red up-conversion intensity on the pump-laser power reveals a cooperative energy transfer mechanism from a pair of Yb3+ ions to one Eu3+ ion.
authors.affiliation: MOE Key Lab of Specially Functional Materials, South China University of Technology, Guangzhou, 510640, People's Republic of China.
authors.forename: C H
authors.initials: CH
authors.lastname: Yang
authors.forename: G F
authors.initials: GF
authors.lastname: Yang
authors.forename: Y X
authors.initials: YX
authors.lastname: Pan
authors.forename: Q Y
authors.initials: QY
authors.lastname: Zhang
mesh_terms: D001881:Borates / Q000138:chemical synthesis* / Q000737:chemistry; D003460:Crystallization; D004871:Erbium / Q000737:chemistry*; D005682:Gadolinium / Q000737:chemistry; D008163:Luminescent Measurements; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry; D033362:Powder Diffraction; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D019265:Spectroscopy, Near-Infrared; D013997:Time Factors; D015018:Ytterbium / Q000737:chemistry*
chemical_list: D001881:Borates; D011108:Polymers; C540417:gadolinium trialuminum borate; D004871:Erbium; D005682:Gadolinium; D015018:Ytterbium