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Structural Features and Color Tunable Photoluminescence of the Binary and Ternary Layered Rare-Earth Hydroxides of (Y,Ln)2(OH)5NO3·nH2O (Ln=Tb, Eu)

A series of layered rare-earth hydroxides (LRHs) of (Y,Ln)2(OH)5NO3•nH2O ( 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 Tb3+ and Eu3+ are successfully incorporated into the Y-LRH host lattice to form solid solutions. Under UV excitation, the binary (Y0.97Tb0.03)- and (Y0.97Eu0.03)-LRHs exhibit their respective characteristic photoluminescence of the Eu3+ and Tb3+ activators. The ternary (Y0.965Eu0.005Tb0.03)-LRH simultaneously shows red and green emissions and both the intensity and emission color can be adjusted by changing the excitation wavelength. Compared with (Y0.995Eu0.005)-LRH, the ternary (Y0.965Eu0.005Tb0.03)-LRH exhibits appreciably enhanced 615nm red-emission, which indicates the existence of non- radiative energy transfer from Tb3+ to Eu3+. The ternary (Y0.965Eu0.005Tb0.03)-LRH also readily undergoes anion exchange with a series of inorganic and organic anions at room temperature.