Organic molecule-mediated synthesis of GdPO4:Eu3+ micro/nano-luminescent materials and MRI tracing performance evaluation

The influence of the introduction of structural modifiers citric acid and acetic acid on the morphology, luminescence properties and magnetic resonance imaging (MRI) tracer properties of GdPO4:Eu3+ micro-nanoparticles synthesized in ethanol system was investigated in the paper. In this system, GdPO4:Eu3+ micro-nanomaterials such as square flake, hexagram, waist drum morphologies can be prepared by adjusting the ratios of structural modifier, phosphoric acid and gadolinium nitrate, respectively. In addition, the synthesized products were analyzed by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), fluorescence spectroscopy (PL), and magnetic resonance imaging (MRI) detection. The products were found to exhibit good crystallinity, particularly in terms of their luminescent properties, which exhibited notable differences. Overall, the luminescent properties of GdPO4:Eu3+ synthesized by citric acid modification were significantly enhanced compared with acetate modification, with at least five times more luminescent intensity than that of acetate modification. And amazingly, the GdPO4:Eu3+ luminescence intensity is strongest when the square flake-hexagram coexisting. The tracer properties of GdPO4:Eu3+ MRI with better luminescent square flake, hexagram, and square flake-hexagram coexisting morphologies were also investigated. It was found that the square flake had better T1-longitudinal relaxation imaging with a relaxation rate r1 value of 0.79 mM−1s−1. This work is a good advancement for organic molecule-mediated modulation, synthesis of gadolinium phosphate-based rare-earth micro-nanomaterials and study of their applications in luminescence and MRI tracing.