Eu0.56Ta2O7: A New Nanosheet Phosphor with the High Intrananosheet Site Photoactivator Concentration

High photoactivator concentration nanosheets Eu0.56Ta2O7 have been prepared by the soft chemical exfoliation reaction of the layered perovskite Li2-xHxEu0.56Ta2O7 with a tetrabutylammonium hydroxide aqueous solution. In-plane X-ray diffraction and TEM and AFM observation results indicate that the Eu0.56Ta2O7 nanosheet is crystalline and retains the layered perovskite structural feature of the bulk precursors. The most intense emission is observed from the 5D0 → 7F2 transition of Eu3+. The intensity of this emission by the host excitation exceeds 18 times that by the direct Eu3+ excitation.