A new resource-rich carbonate luminescent host KNa_(5)Ca_(5)(CO_(3))_(8):A case study activated by Eu^(3+) for red-phosphor purpose

Exploring and designing new luminescent host with rich resource is beneficial to reducing the cost and the large-scale application of luminescent materials.Herein,a series of novel Eu^(3+)-activated KNa5-Ca5(CO3)8 red-emitting phosphors with different Eu^(3+) concentrations were successfully synthesized under mild hydrothermal condition.XRD and SEM characterizations show that all as-prepared KNa_(5)Ca_(5)(CO_(3))_(8):Eu^(3+) samples crystallize in a hexagonal structure,P63 mc(No.186) space group,and show monodispersed hexagonal sheet mo rphologies,within a side length interval about of 2-3μm and a thickness of about 0.6 μm,Eu^(3+) doping within 6 mol% concentration has little influence on the crystal structure of the host,as indicated by XRD,and FT-IR results,but thermal stability changes as shown by the TG-DTA.KNa_(5)Ca_(5)(CO_(3))_(8) phosphors with different Eu^(3+) concentrations can emit red-light under effectively excitation by near-UV light.CIE chromaticity coo rdinates of all KNa_(5)Ca_(5)(CO_(3))_(8):Eu^(3+) phosphors were calculated to locate in red region,and CCT of each sample is the range from 2815 to 3650 K,very close to the tungsten lamp light.Besides,concentration quenching phenomenon appearing at 5 mol% is found to be the result of electric multipolar interaction of Eu^(3+)activators,and the decay lifetime is about1.63 ms,which almost unchanges with Eu^(3+) doping concentration.Importantly,thermal quenching analysis reveals good thermal stability with thermal activation energy of about 0.216 eV.The results reported here demonstrate that KNa_(5)Ca_(5)(CO_(3))_(8) is a promising fluorescent host for LEDs applications.