Luminescent And Temperature Sensing Properties Of Rare Earth Doped Niobate Luminescence Materials

Rare-earth?RE?ion doped up-conversion?UC?luminescent materials have received considerable attention due to their widespread applications in many fields,such as UC lasers,sensors,solar cells,three dimension display,and so on.Therefore,it is necessary to explore a new type material to meet both high efficient UC luminescence and high temperature sensitivity requirements.This dissertation selects niobate as host material which has good chemical and physical stabilities,RE ion doped concentration and host compositions dependent luminescent and temperature sensing properties were systematically studied.The main idea and results are shown as follows:?1?A series of YNbO₄:Er³⁺ phosphors with various Er³⁺ concentrations were synthesized via a traditional high temperature solid-state reaction method.The influence of Er³⁺ concentration on the luminescent properties and temperature sensing in YNbO₄:Er³⁺ phosphors were systematically studied.From lasers working current dependent UC luminescence spectra,it was confirmed that two and three photon processes were responsible for both the green and the red UC emissions respectively excited by 980 and 1:50 nm lasers,which has no apparent dependences on Er³⁺ concentration.However,Er³⁺ concentration has significant influences on the temperature sensing sensitivity of Er³⁺ ions,and the result showed that low Er³⁺ concentration doped YNbO₄ phosphors had high temperature sensing sensitivity.?2?Er³⁺/Yb³⁺ co-doped YNbO₄ phosphors were successfully synthesized via a high-temperature solid-state reaction method.The Er³⁺ and Yb³⁺ concentrations dependent UC luminescence was studied,and the analyses on the relations between the UC luminescence intensity and the laser working current indicated that four-photon and three-photon population processes were co-existent for generating the green UC emissions at higher concentrations of Yb³⁺.In addition,it was found that the temperature sensing properties of YNbV4:Er³⁺/Yb³⁺ phosphors were dependent on the Er³⁺ and Yb³⁺ doping concentrations.Furthermore,based on the obtained temperature response of the UC luminescence phosphors,it was deduced that the sample temperature induced by the irradiation of 1550 nm laser was very sensitive to both the doping concentrations of Er³⁺,Yb³⁺ and the excitation power.?3?LnNbO₄:Er³⁺?Ln= Gd,Y,Lu?phosphors were prepared through a conventional high temperature solid-state method.Host compositions dependent luminescent and temperature sensing properties of Er³⁺ in LnNbO₄ were studied.The results showed that host compositions had obvious effects on the luminescent intensity in both down-conversion and UC luminescence,but it had no influences on the UC luminescence processes under both 980 nm and 1550 nm excitaions' cases.From temperature dependent UC luminescence spectra,it was confirmed host compositions had obvious effect on the temperature sensing performances of Er³⁺ and it was found that LuNbO₄:Er³⁺ phosphors had the highest temperature sensing sensitivity.