Facile synthesis and color-tunable properties of monodisperse β-NaYF:Ln (Ln = Eu, Tb, Tm, Sm, Ho) microtubes.

In this study, monodisperse and uniform β-NaYF hexagonal microtubes were successfully synthesized via a simple hydrothermal method without any organic surfactants, employing Y(OH)CO colloid spheres as precursors. The possible formation mechanism was studied on the basis of a series of time-dependent control experiments and its intrinsic crystal structure. The integrated emission intensity of β-NaYF:0.05Tb is almost 1.78 times stronger than that of α-NaYF:0.05Tb. In addition, the photoluminescence properties of β-NaYF:Ln (Ln = Eu, Tb, Tm, Sm, Ho) were studied in detail, and it was found that the photoluminescence color of β-NaYF:0.03Tm phosphor was close to the standard blue light (0.14, 0.08). Moreover, by co-doping the Tb and Eu ions into the β-NaYF host, multicolor tunable emissions were obtained due to the efficient energy transfer from Tb to Eu at 368 nm excitation. These merits demonstrate that this material may find potential application in color display fields.