Hydrothermal Synthesis And Photoluminescence Properties Of Pr Doped KNBO₃and （K,Na）NbO₃

Potassium niobate and potassium sodium niobate are typical lead-free ferroelectricmaterials. They are becoming a hot research spot for their excellent electromechanicalproperties, nonlinear optical properties and wide application on areas such as electronics,medical diagnosis and treatment. The working temperature of ferroelectric can bedetected in-situ, non-contacted and easily by the luminescent properties of rare earthdoped ferroelectric materials. Results of rare earth element praseodymium (Pr) dopedferroelectric materials such as Ba0.77Ca0.23TiO3were reported. It was found that thepolarizing and modifying the compositions of ferroelectric can enhance the luminousintensity effectively. And it was affirmed that Pr doped NaYF4material could be usedfor sensitive optical temperature detectors. In this paper, the preparation process ofhydrothermal method and photoluminescence properties of Pr doped potassium niobateand potassium sodium niobate were investigated.First of all, powders of potassium niobate and potassium sodium niobate withperovskite structure are prepared successfully and the products have been characterized.The effects of soaking time and the concentration of precursors were discussed. Wesuccessfuiiy reached the destination of controlling for composition, grain sizes bymodified the process. At200℃, pure uniform rhombic potassium niobate particles withperovskite were synthesized by the reaction of10h, size can be controlled from180nmto700nm. We alsoget the different components of Na/K ratio, uniform grain potassiumsodium niobate.Secondly, the preparation by hydrothermal, appearances and principles forphotoluminescence properties of Pr-doped KNbO3are discussed. Pr doped potassiumniobate was prepared by hydrothermal and light-emitting mechanism of potassiumniobate was discussed with a laser of325nm wavelength as the excitation light source.The effects of parameters such as Pr content, post-annealing, and temperature are alsoinvestigated. It is successful to obtain variety of colors by adjusting the intensities ofdifferent emission peaks. It was proved Pr-doped luminescence of potassium niobate issensitive to temperature, and it has the temperature measurement potential. Meanwhile,the relationship between temperature and colors were also investigated.Finally, we studied the preparation by hydrothermal and the photoluminescenceproperties of Pr-doped (K, Na)NbO3. Pr-doped potassium sodium niobate was preparedby hydrothermal method, the relationship between temperature and light intensitywasstudied, The optical temperature sensing properties of Pr-doped potassium sodiumniobate were studied. Particularly, by comparing the properties of optical temperature sensor with three different methods, we realized temperature sensing based onfluorescence intensity ratio of red and blue, the sensor sensitivity reaches6303.33/T2.The results would not only improve the cognizance for processing andphotoluminescence properties of Pr doped synthesized potassium niobate and potassiumsodium niobate, but also can extend to the other ferroelectric materials. Based on thesensitive effects on the photoluminescence properties of Pr, the distribution oftemperature for working ferroelectric materials could be detected in-situ and real-timelyby applications of spectroscopic and colors distinguishing visually.