Facile synthesis and color-tunable properties of monodisperse β-NaYF4:Ln3+ (Ln = Eu, Tb, Tm, Sm, Ho) microtubes

Abstract

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.