Monodisperse and hollow structured Y₂O₃:Ln³⁺ (Ln = Eu, Dy, Er, Tm) nanospheres: A facile synthesis and multicolor-tunable luminescence properties

Highlights: • We reported a simple route to synthesize the Y₂O₃ HNSs. • A possible formation mechanism of the Y₂O₃ HNSs was proposed. • The Ln-doped Y₂O₃ HNSs exhibit characteristic emission with different colors. • White-light-emitting phosphor Y₂O₃:Tm³⁺, Dy³⁺ was also successfully synthesized. - Abstract: A novel, fast and simple method was developed to synthesize the undoped and lanthanide-doped yttrium oxide hollow nanospheres (Y₂O₃⋅HNSs) with multicolored downconversion emission under mild conditions by employing poly (acrylic acid sodium salt) microspheres (PAAS MSs) as active templates followed by a subsequent calcination process. The structure, morphology, formation process, and fluorescent properties are well investigated using various techniques. The results show that the samples can be well indexed to the pure cubic phase of Y₂O₃. The possible formation mechanism of the PAAS MSs, PAA-Y precursor, and Y₂O₃ HNSs are proposed and discussed in detail. Upon ultraviolet excitation, the obtained Y₂O₃:Ln³⁺ (Ln = Eu, Dy, Er, Tm) HNSs exhibit strong red, yellow–green, blue, yellow emission, respectively. Moreover, a novel single-phased and near-UV-pumped white-light-emitting phosphor Y₂O₃:Tm³⁺, Dy³⁺ was also successfully fabricated through optimizing the molar ratio among Tm³⁺ and Dy³⁺ in the Y₂O₃ host. This material may find potential applications in field-emission display devices and white ultraviolet light-emitting diodes (UV LEDs). Furthermore, this synthesis route may be of great significance in the preparation of other hollow spherical materials