Enhancement of reliability and thermal stability of Ca0.2Sr2.73SiO5: 0.07Eu2+ phosphor by completely substitute Ba for Ca in warm LED application

The Ca0.2Sr2.73SiO5: 0.07Eu2+ (CSSO) and Ba0.2Sr2.73SiO5: 0.07Eu2+ (BSSO) phosphors were obtained by conventional high-temperature solid-state method. The tests of X-ray diffraction (XRD), energy-dispersive dispersive spectrometer (EDS), scanning electron microscope (SEM) and their temperature dependent were carried out for the samples. The crystal particles are relatively regular and average particle size is about 15 μm. By mixing BSSO (or CSSO) with Lu2.94Al5O12: 0.06Ce (LuAG) phosphors, the converted LED show a warm white light with the correlated color temperature (CCT) in the range of 2500K5000K with the highest luminescence efficiency (LE) as 153 lm/W. In temperature dependent testing, the emission intensity of BSSO increase by 1.83%, 6.14%, 6.51% and 2.18% compared with that of CSSO in 323 K, 373 K, 423 K and 473 K, respectively. The grain surface is corroded increasingly in the accelerated aging tests of thermal cycling, hydrolysis reaction, high temperature and high humidity (85 °C/RH85%). In three tests, emission intensity of BSSO enhanced 11.24%, 40.54% and 20.52% compared with that of CSSO, separately. The results indicated that BSSO phosphor has higher reliability and thermal stability than CSSO phosphor in a negative external environment for warm LED application.