Preparation And Research Of Metal Silicates And Borates

Silicate and borate are very important solid synthetic materials.The materials have unique structures and properties due to the variety of Si-O and B-O bonding modes.In this paper,different rare earth oxides and silica or boric acid were used as raw materials to prepare single rare earth metal silicate and rare earth metal borate materials by using using flux assisted solid state method,molten salt method and hydrothermal method under different ratios,and reaction conditions.Then the materials were doped with rare earth metal and loaded with graphene,g-C₃N₄ and cucurbit[6]urils(Q[6]),and the characterization and properties of the products were studied.In order to achieve the modulation of photocatalytic or optical properties of rare earth metal silicate and a rare earth metal borate materials.1.Series of rare earth metal(Nd,Gd,Eu,Y)silicate materials were prepared by flux assisted solid-state method,molten salt method and hydrothermal method.The products were characterized by Fourier transform infrared spectroscopy,X-ray diffraction,photoelectron spectroscopy,fluorescence spectroscopy,scanning electron microscopy,ultravioletvisible diffuse reflectance spectroscopy,Raman spectroscopy and thermogravimetric/differential scanning calorimetry.The effects of doping other rare earth metal elements and supported graphene,g-C₃N₄ and cucurbit[6]urils)on the photocatalytic properties and fluorescent properties of yttrium silicate were investigated.The results shown that the calcination temperature of silicate was reduced by flux assisted solid state method and molten salt method.The photocatalytic performance of graphene and g-C₃N₄ on yttrium silicate was improved by nearly 40%,and the photocatalytic performance of Q[6]on yttrium silicate is improved by 15.7%.The luminescence color of yttrium silicate was also affected by graphene,g-C₃N₄ and Q[6],while the luminescence effect of graphene on yttrium silicate was the most obvious,which can be used as blue luminescent phosphor.2.Series of rare earth metal(Nd,Gd,Eu,Y)borate materials were prepared by flux assisted solid state method,molten salt method and hydrothermal method.The products were characterized by Fourier transform infrared spectroscopy,X-ray diffraction,photoelectron spectroscopy,fluorescence spectroscopy,scanning electron microscopy,ultravioletvisible diffuse reflectance spectroscopy,Raman spectroscopy and thermogravimetric/differential scanning calorimetry.The effects of doping other rare earth metal elements and supported graphene,g-C₃N₄ and cucurbit[6]urils)on the characteristics fluorescent light source of yttrium borate were studied.The results shown that the calcination temperature of borate was reduced by molten salt method.The structure,morphology and particle size of gadolinium borate were affected by the calcination temperature,when the calcination temperature is 850?,gadolinium borate was glass ceramics.Double rare earth metal(Nd,Gd)doping and graphene,g-C₃N₄ and Q[6]loading can adjust the luminescence color of yttrium borate,among which gadolinium and neodymium double rare earth element doping and graphene loading can adjust the luminescence color of yttrium borate most obviously.In addition,yttrium borate has good thermal stability and can be applied to high temperature blue phosphor.Compared with other methods,the luminescence effect of yttrium borate loaded with GO,g-C₃N₄ and Q[6]prepared by hydrothermal method is more obvious.