beta-NaGd0 Yb-794(0) Ho-20(0) Tm-001(0) F-005(4) nanoparticles were synthesized through a simple hydrothermal method The nanoparticles crystallized well and exhibited nearly hexagonal morphology and ellipsoidal spheres, as characterized by X-ray powder diffraction and transmission electron microscopy The beta-NaGd0 Yb-794(0) Ho-20(0) Tm-001(0) F-005(4) nanoparticles have an average size of about 23 nm Room-temperature bright white upconversion luminescence in beta-NaGd0 Yb-794(0) Ho-20(0) Tm-001(0) F-005(4) nanoparticles was obtained under single-wavelength diode laser excitation of 980 nm