Structural Features and Color Tunable Photoluminescence of the Binary and Ternary Layered Rare-Earth Hydroxides of (Y,Ln)₂(OH)₅NO₃·<i>n</i>H₂O (Ln=Tb, Eu)

<jats:p>A series of layered rare-earth hydroxides (LRHs) of (Y,Ln)<jats:sub>2</jats:sub>(OH)<jats:sub>5</jats:sub>NO<jats:sub>3</jats:sub>•nH<jats:sub>2</jats:sub>O ( Ln=Tb,Eu), have been synthesized via a hydrothermal route. Crystal structures and optical properties of the materials have been investigated in detail by the combined techniques of XRD, FT-IR, FE-SEM, HR-TEM, and PLE/PL spectroscopies. It is shown that Tb<jats:sup>3+</jats:sup> and Eu<jats:sup>3+</jats:sup> are successfully incorporated into the Y-LRH host lattice to form solid solutions. Under UV excitation, the binary (Y<jats:sub>0.97</jats:sub>Tb<jats:sub>0.03</jats:sub>)- and (Y<jats:sub>0.97</jats:sub>Eu<jats:sub>0.03</jats:sub>)-LRHs exhibit their respective characteristic photoluminescence of the Eu<jats:sup>3+</jats:sup> and Tb<jats:sup>3+</jats:sup> activators. The ternary (Y<jats:sub>0.965</jats:sub>Eu<jats:sub>0.005</jats:sub>Tb<jats:sub>0.03</jats:sub>)-LRH simultaneously shows red and green emissions and both the intensity and emission color can be adjusted by changing the excitation wavelength. Compared with (Y<jats:sub>0.995</jats:sub>Eu<jats:sub>0.005</jats:sub>)-LRH, the ternary (Y<jats:sub>0.965</jats:sub>Eu<jats:sub>0.005</jats:sub>Tb<jats:sub>0.03</jats:sub>)-LRH exhibits appreciably enhanced 615nm red-emission, which indicates the existence of non- radiative energy transfer from Tb<jats:sup>3+</jats:sup> to Eu<jats:sup>3+</jats:sup>. The ternary (Y<jats:sub>0.965</jats:sub>Eu<jats:sub>0.005</jats:sub>Tb<jats:sub>0.03</jats:sub>)-LRH also readily undergoes anion exchange with a series of inorganic and organic anions at room temperature.</jats:p>