Optical properties, energy transfer and thermal stability of spherical nano-phosphor YPO4:Eu3+:Sm3+

A series of phosphors of Sm3+ and Eu3+ single-doped or co-doped YPO4 matrix are synthesized by the hydrothermal method. X-ray diffractometer (XRD), scanning electron microscope (SEM), fluorescence spectrophotometer (FL), ultraviolet–visible near infrared spectrometer (UV) and Fourier transform-infrared (FI-IR) spectrophotometer are used to analyze and characterize composition, structure, morphology, luminescent properties, fluorescence lifetime and fluorescence thermal stability of the sample. The analysis results show that the phosphor has a tetragonal crystal structure, and the morphology is the nano-sphere with the diameter of 60–100 nm. Under excitation of 395 nm and 404 nm near-ultraviolet light, YPO4:Sm3+:Eu3+ emits intense red and orange red light. In the phosphor YPO4:Sm3+:Eu3+, Sm3+ and Eu3+ undergo a process of mutual energy transfer; the critical distance of energy transfer is 1.109–2.392 nm; the energy transfer mechanism is electric dipole-electric dipole interaction; the energy transfer efficiency can reach over 65%. For the optimum product YPO4:2%Sm3+:8%Eu3+, the color coordinates are X = 0.6137, Y = 0.3813; and the fluorescence lifetime is 0.219 ms. The phosphor has good thermal stability, and the thermal quenching activation energy is 0.2053 eV. The tailored yttrium orthophosphate nanoparticles significantly displayed potentiality in the field of optical displays, and also demonstrated the applicability in the biological field.