Facile synthesis and color-tunable properties of monodisperse β-NaYF4:Ln3+ (Ln = Eu, Tb, Tm, Sm, Ho) microtubes†
In this study, monodisperse and uniform β-NaYF4 hexagonal microtubes were successfully synthesized via a simple hydrothermal method without any organic surfactants, employing Y(OH)CO3 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-NaYF4:0.05Tb3+ is almost 1.78 times stronger than that of α-NaYF4:0.05Tb3+. In addition, the photoluminescence properties of β-NaYF4:Ln3+ (Ln = Eu, Tb, Tm, Sm, Ho) were studied in detail, and it was found that the photoluminescence color of β-NaYF4:0.03Tm3+ phosphor was close to the standard blue light (0.14, 0.08). Moreover, by co-doping the Tb3+ and Eu3+ ions into the β-NaYF4 host, multicolor tunable emissions were obtained due to the efficient energy transfer from Tb3+ to Eu3+ at 368 nm excitation. These merits demonstrate that this material may find potential application in color display fields.