Scientists have developed a yellow phosphor that can be used
to provide a pleasing white light with a warm color temperature when combined
with a blue light-emitting diode (LED) chip. Although YAG: Ce-based white LEDs
show great promise as a highly efficient and long-lasting form of domestic
lighting, their cool bluish-white light makes them undesirable for use in the
home. Scientists from the USA and China have now shown that a new phosphor,
Ba0.93Eu0.07Al2O4, when combined with a blue InGaN LED, provides a pleasing
white light with a warm colour temperature of less than 4000K and a high
colour-rendering index of more than 80. The phosphor has an orthorhombic
structure and was manufactured by carbothermal reduction and vapour phase
deposition in a tube furnace system. This work suggests that high-quality,
warm-white lighting can be achieved using a combination of a single phosphor
with single-emitting-center and a blue LED chip.