Preparation And Properties Of Germanate Red Light Conversion Agents Applied In Greenhouse Flim

Facility agriculture,an important component of modern agriculture,has been made a explosion for the agricultural needs of human.As one of advanced materials to promoting energy saving and comsumption reduction for facility agricuulture,light-conversion agricultural film optimizes growth environment for plants,improves yield and quality of plants and makes crop's supply period control via making selections and transitions of the solar spectrum and controling photo-temperature intelligently.Photosynthesis is a direct application of light for plants.Researches show that the light with the wavelength from 400 to 480 nm and from 610 to 680 nm can be efficiently absorbed by cholorophyll to improve the efficiency of photosynthesis.However,the light with the wavelength from 290 to 350 nm and from 510 to 600 nm is hardly utilized during the photosynthesis.In other word,not all the light in the solar spectrum can accelerate plants photosynthesis.Consequently,the exactly effect of light-conversion agricultural flim is improving the utilization of the sunlight to shorten the growth period of plants,increase crop's yield and quality by converting the lights which cannot benefit even go against photosynthesis to the light which is can be applied as photosynthesis fertilizer.Light-conversion agricultural flim rely on light-conversion agents attached to the plastic flim to achieve regulation of light.However today,inorganic light-coversion agents are restrained by the shortages of photostability,fluorescence decay,flim compatibility and light transmittance.As a result,it's promising to develop inorganic light-conversion agents with high photosynthetic efficiency,suitable spectra for plants growth,high stability,lowcost and nontoxicity.In this paper,with comprehensive consideration of effects of different light to photosynthesis,Mn4+ actived germanate red light-conversion agents applied in agricultural light-coversion flim have been synthesized and their morphology andIV luminescence properties have been improved.The products can emit red light centred at around 659 nm via near-UV excitation.X-ray power diffraction(XRD),Ultraviolet-Visible spectrophotometer(UV-VIS),Spectrofluorometer,Fourier transform infrared spectrometer(IR),Field emission scanning electron microscope(FESEM),X-ray photoelectron spectroscopy(XPS)have been carried out to investigate the crystal struture,luminescence properties,mophology and energy structure.The major research contents include:(1)Mg2Ge O4:Mn4+ has been synthesized by high temperature solid-state method.All the raw materials with porper proportions were mixed in an agate mortar with addition of ethanol and then triturated thoroughly.The obtained powders were dried by ethanol evaporation and transferred to a corundum crucible,followed by annealing at 1150 o C in an ambient atmosphere with a heating rate of 10 o C/min for 13 hours in a muffle furnace.Based on the obtained Mg2 Ge O4:Mn4+,different rare-earth ions have been co-doped into the matrix.Analyse the crystal structures,luminescence properties and mophology of the products.The results show that Sm3+,Dy3+ or Gd3+ co-doping achieves emission enhancement in Mg2 Ge O4:Mn4+ without changing the crystal structure,mophology and the shape of the Mg2 Ge O4:Mn4+.(2)Mg28Ge10O48:Mn4+,Bi3+ nanoparticles has been synthesized by coprecipitation method.All the raw materials were dissolved in deionized water.Adjust the p H of the solution with HNO3 to obtain precipitate,then anneal the precipitate in a muffle furnace to obtained Mg28Ge10O48:Mn4+,Bi3+ nanoparticles.As a flux,Bi3+ promotes the matrix to form crystal structure as Mg28Ge10O48.Metal-to–metal charge transfer about Bi3+(6s2)/Ge4+(3d10)? Bi4+(6s1)/Ge3+(4s1)and energy transfer between Bi3+ and Mn4+ are induced to explain the great emssion enhancement.Mg28Ge10O48:Mn4+,Bi3+ nanoparticles with the particle sizes around 35 nm have been prepared under the condition of annealing the precipitate,obtained at p H=10,with 1.25% Bi3+ co-doped at 950? for 4h.(3)Mg28-xZnx Ge10O48:Mn4+ nanoparticles has been synthesized by sol-gel method.Co-doping Zn2+ into the matrix to prepared Mg28-xZnx Ge10O48:Mn4+ with strong red emission via eutectic-like flux effect and band-gap engineering because of the similar radii and the same valence state between Zn2+ and Mg2+ and the energy structure ofZn2+.During the sol-gel method process,the L-tartaric acid offer positions to form the polymeric arrays with Mg2+ and Ge4+ alternately arranged avoiding the phase segregation.As a result,Mg28-xZnx Ge10O48:Mn4+ nanoparticles with the particle sizes around 20~25 nm have been prepared.The best synthesis condition is that prepare the precursor with ratios of Mg2+:Zn2+=3.25:0.75 and L-tartaric acid/Ge4+=5,then transfer the precursor into a 900? muffle furnace and move out the product directly from the 900? muffle furnace after 4h annealing.In this paper,the research of Mn4+ doped germanate red light conversion agent for agricultural film provides a very important reference for the selection of red light conversion agent.