Morphology And Luminescence Properties Of NaLnF₄（Ln=Er,Y,Yb,Tb,Tm,Ho） Nanocrystalline Doped With Ca²⁺

Rare earth luminescent nanocrystals have unique photoluminescence propertiesdue to unique4f electronic structure of rare earth elements, which are pofential to bewidely used in fluorescent tags, anti-counterfeiting, cell imaging, solar cells and otherfields. Rare earth fluoride with low phonon energy is currently the best substratematerials. It is of great significance for the utilization coefficient of rare earth in developping new rare earth nanomaterials and looking for rare earth nanocrystalscontrollable synthesis methods. However the alkaline earth ion is commonly used asthe matrix cation for materials in rare earth fluoride because its ion radius is similar tothe rare earth metal ion radius. So, the main work of this dissertation focused on theinfluence of the size, the morphology and the luminescence property with theexistence of Ca2+.The main contents and conclusions are as follows.(1) Near-monodisperse NaLnF4(Ln=Er, Yb, Y, Tb, Ho, Tm) nanocrystals weresynthesized via solvothermal method in which the system of oleic acid, eunatrol,alcohol and water are mixed together to form the microemulsion. The nanocrystals arehexagonal structure.(2) With the existence of Ca2+, a series of NaLnF4(Ln=Er, Yb, Y, Tb, Ho, Tm)nanocrystals with different morphologies and sizes were synthesized by solvothermalmethod. The nanocrystals with different ratios of length to diameter were synthesizedby controlling the content of Ca2+under same reaction conditions. The diameter of theNaEr/Tb/HoF4nanorods increases gradually but the length decreases with the increaseof doped Ca2+. The diameter of the NaYb/YF4nanorods decreases gradually but thelength increases with the increase of doped Ca2+. The NaTmF4nanopipes turn intonanorods with the increase of doped Ca2+. So, the ratio of length to diameter ofnanocrystals can be controlled by adding different contents of Ca2+.(3) The content of doped Ca2+has impacts on the photoluminescence propertiesof nanocrystals. Under the proper light source excitation, nanocrystalline can generatephotoluminescence The luminous intensity of NaErF4increased and the luminousintensity of NaYbF4decreased with the increase of doped Ca2+. The luminousintensity of NaYF4firstly increased with the increase of doped Ca2+. In0.05tendencyfor doping, near infrared peak emission is three times than the undoped. The luminousintensity of NaTbF4decreased with the increase of doped0.3mmol Ca2+. As a result,the control of the luminescence of That is to say, controllable luminescence of NaLnF4(Ln=Er, Yb, Y, Tb, Ho, Tm) nanocrystals can be realized by different Ca2+addition.