激光照明用荧光陶瓷研究进展OA北大核心CSTPCD

Solid-state lighting is one of the most promising technologies in the 21st century due to its high luminous efficiency,faster responding,energy-saving,environmentally friendly,and longevity.It relies on solid-state electronic components to achieve the conversion of electrical energy to light energy.At present,solid-state lighting mainly includes light-emitting diodes(LEDs)and laser diodes(LDs).The luminous efficiency of existing LEDs decreases with the auger effect as the input power increases.They cannot achieve a higher light efficiency output.However,LDs have a higher efficiency,a stronger brightness and a longer lighting distance for the efficiency degradation of LEDs at high power densities.The existing color conversion materials that can be used for laser diodes are single crystals,phosphor ceramics,phosphor-in-glasses,phosphor films,etc..Phosphor ceramics are the most promising color conversion materials for LDs with high thermal conductivity,good optical properties,and controllable microstructures. This review discussed the current research status of forming methods,sintering processes,component selection,and structural design of phosphor ceramics for laser diodes.This review summarized the design requirements of LDs for phosphor ceramics,such as thermal saturation characteristic,optical saturation characteristic,luminous efficiency,color rendering index,mechanical properties,etc..This review also elaborated the performance requirements of phosphor ceramics for practical applications.The preparation technologies of phosphor ceramics were summarized.The preparation methods of the powders included chemical coprecipitation method,hydrothermal method,sol gel method,etc..The forming methods of powder included dry pressing,cold isostatic pressing,molding by slip casting process,casting molding,gel casting,etc..The sintering methods of ceramics include pressureless sintering,gas pressure sintering,vacuum sintering,spark plasma sintering,hot pressed sintering,hot isostatic pressing,etc.. For selecting and optimizing raw materials,sintering aids are one of the important factors affecting the sintering of phosphor ceramics.In the design of the composition of phosphor ceramics,the luminescence performance is adjusted via designing the types of matrix elements in oxide and nitrogen(oxide)phosphor ceramics.The luminescence behavior of phosphor ceramics is analyzed via introducing different luminescent centers into the same matrix.In addition,the introduction of a second phase is also chosen to improve both the blue light absorption rate and the heat dissipation performance of ceramics in order to further enhance the luminescent performance of phosphor ceramics.In the structural design of phosphor ceramics,some methods such as introducing pores,multi-layer structures,and surface modifications are used to further improve the luminescence efficiency and color rendering index of phosphor ceramics. Summary and prospects Lighting penetrates every aspect of life,i.e.,daily lighting,projection displays,automotive lighting,and other industries.The requirements for lighting devices in various industries are increasing and gradually moving towards to high power and high brightness.This review represented recent research progress on phosphor ceramics in molding technology,sintering process,material design,and other aspects.At present,there are still shortcomings in the preparation of phosphor ceramics,such as single preparation method,limited variety,obvious thermal and optical saturation phenomena.Further improvements are needed in the following areas:1)Preparation of highly active nano-powders and sintering additives are related to optical and mechanical properties of phosphor ceramics.Sintering aids promote liquid-phase mass transfer during ceramic sintering process and also impact the structure of the matrix lattice;2)The forming method of ceramics directly determines the stacking situation of powder raw materials,which in turn affects the sintering density.The appropriate molding methods can obtain ceramic bodies with uniform composition,constant shape,and strength,making the particles tightly being connected and promoting facilitated transport during the sintering process;3)The sintering of phosphor ceramics requires a high temperature and a certain sintering environment,such as reduction atmosphere,oxidation atmosphere,vacuum environment,etc..The sintering conditions that thermal equipment can provide also affect the design and selection of sintering conditions for phosphor ceramics.The selection of thermal equipment has a significant impact on the sintering process of phosphor ceramics,and determines the range of sintering condition.Further promoting the technological progress of thermal equipment plays a decisive role in improving the performance of phosphor ceramics;4)The emission spectrum of phosphor ceramics still lacks a red spectral component,so further expanding the types of red phosphor ceramics will inevitably effectively improve the color rendering index of phosphor ceramics;5)The appropriate non-luminescent second phase preparation of multiphase phosphor ceramics is beneficial to improving the luminescence efficiency of phosphor ceramics;and 6)The intense heat dissipation and luminescence performance of luminescent materials are still a key to their widespread application.