Investigation On Rare-earth And Transition Metal Ions Doped Oxyfluoride Glass-ceramics For Glass Greenhouse

Nowadays, the increasingly growing energy demand throughout the whole world makes it essential to find substitution for the fossil fuel. Sunlight is such a ubiquitous form of energy, as solar energy is affordable, inexhaustible and environmental friendly. Green Plant can seek out sunlight for photosynthesis, which helps sustain almost all life on earth. Currently, increases in yield potential will rely in large part on improved photosynthesis.For the green plant, they are on the preference of absorbing more reddish orange(640~680 nm) and bluish violet(430~500 nm) lights than any other wavelengths. Longer wavelengths are not absorbed by chlorophylls and other photosynthetic antenna pigments, while shorter wavelengths are even harmful to the plant. An ability to use UV and near-infrared(NIR) radiation would greatly improve the efficiency of photosynthesis.To promote the growth of the green plants, the plastic greenhouses are generally used when the temperature is low. However, the poor transparency of the plastic hinders the photosynthesis of the green plants. To solve this problem, the glass greenhouses with good light transmittance, thermal retardation, and long service life, have been given deep concern. For the host materials, the glass ceramics are more promising because they not only have the merits of the glass, but also contain nano-size crystallite phases that can improve the optical properties without loss of transparency. Oxyfluoride glass ceramics, which contain fluoride nano-crystals inside the glass matrices, have particular properties. Fluoride nano-crystals in the glass matrices provide the low phonon energy environment for optically active ions, and the glass matrices, which are close to the oxide glasses, guarantee the good chemical and mechanical properties of these composite materials.This paper mainly studied for preparation, photoluminescence property of rare-earth and transition metal ions doped glass and glass-ceramics for glass greenhouse, discusses the feasibility analysis of some ion matching.Based on the 50SiO2-20Al2O3-20CaF2-10 NaF, the Ce3+/Er3+/Yb3+ tri-doped oxyfluoride glass ceramics have been synthesized. Under the 980 nm excitation, the glasses ceramics can emit strong reddish orange light because of the ET from Yb3+ to Er3+, which can also be obtained via down-conversion process under UV excitation, while the excitation of Er3+ itself is another pathway to get the strong reddish orange light. All these three pathways can obtain the reddish orange light, which highly matches with the absorption spectrum in red wavelength region of chlorophylls In addition, the luminescence of Ce3+ itself includes the blue(400~500 nm) wavelength region, which matches well with the other absorption region of chlorophyll. Thus, our glass ceramics can use wider-ranging wavelength sunlight for photosynthesis.In addition, the Ce3+/Mn2+/Yb3+ tri-doped oxyfluoride glass have been synthesized. Mn2+ possesses a broadband luminescence. The energy transfer between the Ce3+/Mn2+ is much more efficient than that of the Ce3+/Er3+. It is a more promising material for practical application.In summary, by the rare-earth and transition metal ions doped, the samples can efficiently convert the ultraviolet and NIR lights into reddish orange and the bluish violet light, which matches well with the spectrum needed for photosynthesis. The down-converting and up-converting materials can enrich the action spectrum of photosynthesis in the UV, Vis and NIR range. Thus, our materials may be applied to glass greenhouses to improve the photosynthesis efficiency of the green plants.