LAUSR

Majority of Mn4+ activated oxide phosphors have the wavelength of excitation and emission suitable for acceleration of plant growth as light converter from sunlight to deep red. Here, it is observed that 60% increase of red emission of Sr4Al14O25:0.01Mn4+ is found by substituting 0.1Ga3+. It is clarified that the increase is originated from a unique mechanism of breaking parity forbidden transition under the substitution of cation in d–d transition by using the tool of special aberration corrected transmission electron microscope(AC‐STEM), pre‐edge peak (1s→3d) Mn K‐edge X‐ray absorption near edge structure (XANES), extended X‐ray absorption fine structure (EXAFS), Rietveld analysis of X‐ray diffraction (XRD) patterns, and reflection spectra. Further, a combination of substituted Ga, Mg, and special double flux H3BO3/AlF3 is found to tremendously increase the emission intensity (355% up). Actual growth of chlorella and rose is examined by a combination of the cheap Sr4Al14O25:0.01Mn4+,0.007Mg2+,0.1Ga3+ and a unique reflection typed phosphor‐film system as sunlight converting system. Optical density of chlorella and height of rose grass is increased by 36±14% and 174±80% compared with nonphosphor‐film, respectively.