A novel red emitting NaBa12B7O21F4:xEu3+phosphor: Synthesis, structure and luminescence properties

Cation vacancy-boosted BaZnB4O8:xEu3+ phosphors with high quantum yield and thermal stability for pc-WLEDs

“…Based on the slope of linear fitting, the activation energy ΔE was determined to be approximately 0.234 eV, which is much higher than previously reported red phosphors, including NaBa 12 B 7 O 11 F 4 :Eu 3+ (0.224 eV) and Ca 3 Y 2 B 4 O 12 :Eu 3+ (0.179 eV). 58,68 The higher activation energy further confirms the superior thermal stability of BZBO:0.50Eu 3+ . In addition, the variation of CIE chromaticity coordinates with temperature can also be utilized to reflect the thermal stability of the BZBO:0.50Eu 3+ phosphor.…”

“…The critical quenching concentration of Eu 3+ ions is about 50% in the BZBO host, higher than in other borate hosts like Ba 3 ScB 3 O 9 (5%), NaBa 12 B 7 O 11 F 4 (14%), and CsBaB 3 O 6 (1.2%). 44,57,58 The high quenching concentration may be the result of cation vacancies caused by heterovalent ion substitution in the unique layered structure host. With the increase of Eu 3+ ion concentration, the distance between adjacent Eu 3+ ions decreases, the non-radiative transition between luminescent centers increases, and hence leads to a concentration quenching phenomenon.…”

“…6(b), the emission intensity of pc-WLEDs at the normal operating temperature (423 K) can maintain about 82.8% of its value at room temperature, which is greater than most reported red phosphors like NaBa 12 B 7 O 11 F 4 :Eu 3+ (43.2%), Ba 3 ScB 3 O 9 :Eu 3+ (55.8%), and Ca 3 Y 2 B 4 O 12 :Eu 3+ (72.1%). 57,58,68 Moreover, the quenching temperature ( T 0.5 ) is the temperature at which half of the initial emission intensity is reached and is also used to evaluate thermal stability. T 0.5 of BZBO:0.5Eu 3+ exceeds 473 K, further proving good thermal stability.…”