Structure and photoluminescence of Mg–Al–Eu ternary hydrotalcite-like layered double hydroxides

A series of Mg–Al–Eu ternary hydrotalcite-like layered double hydroxides (LDHs), with Eu/Al atomic ratios of ∼0.06 and Mg/(Al+Eu) atomic ratios ranging from 1.3 to 4.0, were synthesized by a coprecipitation method. The Mg–Al–Eu ternary LDHs were investigated by various techniques. X-ray diffraction (XRD) results indicated that the crystallinity of the ternary LDHs was gradually improved with the increase of Mg2+/(Al3++Eu3+) molar ratio from 1.3/1 to 4/1, and all the samples were a single phase corresponding to LDH. The photoluminescent (PL) spectra of the ternary Mg–Al–Eu LDHs were described by the well-known 5D0–7FJ transition (J=1, 2, 3, 4) of Eu3+ ions with the strongest emission for J=2, suggesting that the host LDH was favorable to the emissions of Eu3+ ions. The asymmetry parameter (R) relevant to 5D0–7FJ transition (J=1, 2) dependant of the atomic ratios of Mg2+/(Al3++Eu3+) was discussed, and was consistent with the result of XRD.