Synthesis And Characterization Of Fluoride Red Phosphors

White LED is widely attention because of the advantages of small size,long life,no pollution,and fast response.The traditional white LED is the combination of InGaN LED chip and yttrium aluminum garnet excited by cerium ion to obtain white light.However,according to the principle of the three primary colors of light,the lack of red light component will cause the LED to a higher color temperature and a poor color rendering index.To a large extent,it limits the use of warm white LEDs in daily life.In order to overcome this disadvantage,a red phosphor was developed for white LED chip.At present,the fluoride phosphor activated with Mn4+has attracted much attention,mainly because of the low price,simple,fast and efficient synthesis method,and excellent and stable luminescent performance.The most commonly used preparation method is the wet chemical etching method,the phosphor prepared by this method has relatively good performance.However,this method is limited by the high cost.The red phosphor prepared by the co-precipitation method using cheap raw material TiO2 instead of titanium has good thermal stability and excellent luminous performance.At present,there are relatively few reports on the preparation of red phosphors by the co-precipitation method,which has a broader development space.In this paper,K2SiF6 and K2TiF6 red phosphors were prepared by co-precipitation method with Mn4+as activator.H2SiF6 and H2TiF6 were used to replace SiO2 and TiO2.This method improves the luminescent properties of phosphors,and explores the influence of the amount of raw materials and experimental conditions on their properties.In order to reduce the poison and pollution of hydrofluoric acid,a new method combining the co-precipitation with hydrofluoric acid-free hydrothermal is used to improve the performance of the sample.The main research contents and results are as follows:1.K2SiF6:Mn4+was prepared using H2SiF6 to replace SiO2 as raw material.The phase,morphology and fluorescence performance of the sample was characterized.The optimal amount of raw materials for the synthesis of K2SiF6:Mn4+phosphor was determine.2.K2TiF6-based red phosphor was synthesized by co-precipitation method.And the better experimental conditions and synthesis conditions were determined:the dosage of Mn4+is 0.0005 mol,HF is 23 ml,KHF2 is 0.05 mol,H2TiF6 is used as titanium source and stirring time is 120 min.3.The experimental scheme of hydrofluoric acid free hydrothermal method was optimized.The co-precipitation method is integrated into the hydrofluoric acid free hydrothennal method.The highly toxic and corrosive hydrofluoric acid is replaced by the nontoxic H3PO4/KHF2.The XRD diffraction peak spectrum of the sample can match the standard card.The particle morphology after the optimization of the experimental scheme is more regular,smoother and more evenly distributed,and the sample shows stronger emission.