Study On Preparation And Performance Of Properties Of Rare Earth Fluoride Fluorescent Materials

Inorganic rare earth luminescent materials are an important class of luminescent materials.They have attracted the attention of researchers due to their rich luminescent colors and excellent luminescent properties,and are now widely used in many fields such as lighting,display,and detection.As we all know,the richness of the luminescent color of inorganic rare earth luminescent materials mainly depends on the rich 4f-5d energy level transition of rare earth ions,which is given by the special electronic configuration of the corresponding rare earth element atoms,so the preparation of various inorganic luminescent materials by doping rare earth ions is an important research field of rare earth applications.Until now,there have been countless researches on rare earth luminescent materials,and their host materials cover many kinds of compounds including oxides,fluorides,oxyfluorides,tungstates,molybdates,phosphates,carbonates,vanadatess,etc.,and breakthrough progress have also been made in various aspects such as synthesis methods,research areas and application fields.Nevertheless,the research on rare earth luminescent materials still needs to be developed,such as further improving the luminous efficiency,reducing the production cost and performing performance optimization.In addition,multi-color lighting and temperature-sensitive materials are also the focus of current research.In general,rare earth luminescent materials have been greatly restricted in application due to the existence of some shortcomings（such as insufficient stability,low luminous efficiency,high preparation cost,etc.）.Therefore,the biggest challenge we are currently facing is the preparation of phosphor materials with low-cost and high-performance,at the same time,it is also an urgent task to find new types of luminescent materials with industrial production and application value.Since the fact that the performance of a material largely dependent on its microstructure,it’s of great significance to design and synthesize materials with different microstructures according to needs to improve their performance and explore their potential applications.Therefore,the hydrothermal synthesis method,which combines the advantages of simple operation,environmental protection,stable system,low cost and easy control,is an ideal preparation method for the synthesis of materials.The research work of this paper mainly includes the following three parts:（1）Ba₃Sc₂F₁₂,[Ca Y]F₂,and Ba₂La F₇ crystals were prepared by a simple hydrothermal synthesis method,and adjust the microscopic morphology of the crystals by changing the experimental conditions（such as reaction temperature,reaction time,fluorine source,additives,and doping ions,etc.）.At the same time,the growth mechanism of crystals was explored,especially the evolution relationship between several different morphologies of[Ca Y]F₂ crystals,and the controlled synthesis of the final products with different crystal planes exposed was realized by introducing surfactants.（2）The phosphors with rich luminescence colors were prepared by doping rare earth ions(Yb³⁺,Er³⁺,Tm³⁺,Ho³⁺,Ce³⁺,Tb³⁺,Eu³⁺,Sm³⁺,Dy³⁺,etc.),and their up/down conversion luminescence properties were explored,especially the optimization of the luminescence performance was realized through morphology adjustment under the same doping amount of rare earth ions.And the phenomenon and mechanism of energy transfer between rare earth ions and the light color changes that occur in the process were also studied.For example,in the process of Tb³⁺→Eu³⁺energy transfer in Ba₂La F₇host,the regulation of green light→warm yellow light→orange light→red light was realized,and during the Ce³⁺→Tb³⁺energy transfer process of the[Ca Y]F₂ host,the luminous color transitions from blue to blue-green,and finally to green.（3）Based on the temperature dependence of the fluorescence intensity ratio（FIR）between the upper and lower energy levels of the thermal coupling energy level pair of Er³⁺(²H_11/2 and ⁴S_3/2),the temperature sensing capability of the Ba₃Sc₂F₁₂:Yb³⁺,Er³⁺phosphor was evaluated.The above-mentioned three phosphors have the advantages of complete crystal form,adjustable morphology,good crystallinity,and excellent performance,they have important potential applications value in many fields of life such as lighting,display,agriculture,medical treatment,biomarking,and energy.