NaEuF4 nano-/submicro-crystals with various morphologies including regular nano-spheres,submicro-spheres,submicro-spindles and hexagonal submicro-rods were prepared through a facile hydrothermal process by adjusting the pH value and the molar ratio of Na3Cit/Eu3+ in the precursor solution.The resultants were characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FE-SEM),transmission electron microscopy(TEM)and photoluminescence spectroscopy(PL).The plausible formation mechanisms for the morphology-varied NaEuF4 crystals were proposed based on the FE-SEM observation.From the spectroscopic study on the derived nanocrystals,it was found that photoluminescence intensity of the NaEuF4 nano-/submicro-spheres was strongly dependent on the particle size; the luminescence intensity of 5D1 level of Eu3+ increased with the increase of sample temperature owing to the thermal excitation from 5D0 level; the fluorescence intensity of 5D0 level was linearly dependent on the sample temperature.The linear-dependent fluorescence intensity of 5D0 level indicates its potential application in temperature sensing.In this sense,the temperature sensing performance for the samples with different particle sizes was experimentally studied,and it was found that the temperature sensitivity increased with the decrease of particle size.