Tunable color temperature solid state white light source using flux grown phosphor crystals of Eu~(3+), Dy~(3+) and Tb~(3+) activated calcium sodium molybdenum oxide

摘要

Solid state light sources with dynamically tunable color temperature in the range of 3000-6000 K with chromaticity coordinates lying on the Planckian black body curve has been designed using mixtures of narrow emissions at 615 nm, 575 nm and 550 nm. These respective emissions lines were generated by individual phosphor crystals of trivalent rare earth (RE~(3+)) species, europium (Eu~(3+)), dysprosium (Dy~(3+)) and terbium (Tb~(3+)) activated calcium sodium molybdenum oxide (Ca_(1-2x)Na_xMoO_4:RE~(3+)_x), when excited by near-ultra-violet (NUV) light emitting diode (LED) with emission wavelength of 380 nm. Highly luminescent crystals of these compounds have been grown from molten solutions (flux) of molybdenum (Ⅵ) oxide. The flux grown crystals exhibit emission intensity 2-4 times more than phosphor powders of the same compounds synthesized by traditional solid-state reactions. An optimum flux to solute ratio of 2.5 and solute dissolution temperature of 1100 ℃ resulted in the largest size crystals.