title: The effects of Gd3+ substitution on the crystal structure, site symmetry, and photoluminescence of Y/Eu layered rare-earth hydroxide (LRH) nanoplates.
abstract: Well crystallized nanoplates of the (Y(0.95-x)Gd(x)Eu(0.05))(2)(OH)(5)NO(3)·nH(2)O ternary layered rare-earth hydroxides (LRHs), synthesized hydrothermally, have been investigated with emphasis on the effects of Gd(3+) substitution for Y(3+) on the structural features and optical properties. Characterizations of the materials were achieved by the combined techniques of XRD, FT-IR, TEM, DTA/TG, and optical spectroscopies. The results showed that Gd(3+) substitution leads to linearly expanded ab plane, shortened interlayer distance (c/2), and reduced hydration (smaller n value) of the crystal structure. As a consequence, the Ln(3+) partially shifts from the C(4v) to C(1) site symmetries and thus leads to systematically altered photoluminescence behaviors. Under the (7)F(0)→(5)L(6) transition excitation of Eu(3+) at 394 nm, both the (5)D(0)→(7)F(2) to (5)D(0)→(7)F(4) and the 595 nm (5)D(0)→(7)F(1) to 590 nm (5)D(0)→(7)F(1) intensity ratios linearly increase towards a higher Gd(3+) content. The incorporated Gd(3+) cations selectively sensitize emission from the C(1)-site Eu(3+) and produce a new charge transfer (CT) excitation band at ∼254 nm. With this, the desired 615-nm red emission is obtainable either under intra-4f(6) transition excitation of Eu(3+) or by exciting the CT band. The materials have similar fluorescence lifetimes of 0.85 ± 0.05 ms for the 615-nm emission, irrespective of the Gd(3+) content and excitation wavelength.
authors.affiliation: Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Materials and Metallurgy, Northeastern University, Shenyang, Liaoning 110004, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Wu
authors.forename: Ji-Guang
authors.initials: JG
authors.lastname: Li
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhu
authors.forename: Jinkai
authors.initials: J
authors.lastname: Li
authors.forename: Renzhi
authors.initials: R
authors.lastname: Ma
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Sasaki
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Li
authors.forename: Xudong
authors.initials: X
authors.lastname: Sun
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Sakka