Quaternary and higher compositions allow adjusting simultaneously the band gap and the lattice constant, allowing increasing radiant efficiency at wider range of wavelengths; for example AlGaInP is used for LEDs.
2.
With new untarnished reflectors, radiant tubes have a Downward Radiant Efficiency of about 60 % . [ The other 40 % comprises unrecoverable upwards radiant + convective losses, and, flue losses .]
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