Study on Heat Treatment Process of Nano Titanium Dioxide
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摘要: 以四氯化钛为原料,采用碱中和法制备水合二氧化钛,然后在不同温度下热处理分别制备锐钛型纳米二氧化钛和金红石型纳米二氧化钛。采用拉曼光谱、XRD和紫外可见光谱等手段分析了热处理过程对样品的晶体结构、比表面积、微孔体积、紫外吸收光谱等性能的影响。试验结果表明,未经热处理的样品存在氧空位缺陷,具有较大的晶格畸变,随着热处理温度的提高,样品晶粒尺寸从6 nm逐渐长大至70 nm,比表面积从186 m2·g-1减少至5.6 m2·g-1,总孔体积从0.085 cm3·g-1减小至0.001 3 cm3·g-1,晶型由无定型向锐钛型和金红石相逐步转化,晶格畸变逐渐减小。在600℃以下热处理样品为锐钛型,在600~650℃的温度下处理形成金红石与锐钛的混晶,680~750℃有六钛酸钠生成,800℃以后全部转化为金红石结构。Abstract: Titanium tetrachloride was used as raw material to prepare hydrated titanium dioxide by alkali neutralization method,and then anatase nano-TiO2 and rutile nano-TiO2 were prepared by heat treatment at different temperatures.The effects of heat treatment on the crystal structure,specific surface area,pore volume and UV absorption spectrum of the sample were analyzed by Raman spectroscopy,XRD and UV-visible spectroscopy,respectively.The experimental results show that the unheated samples have oxygen vacancy defects and have large lattice strain.With increase of the heat treatment temperature,the grain size of the samples grows from 6 nm to 70 nm with the specific surface area decreased from 186 m2·g-1 to 5.6 m2·g-1 and the total pore volume decreased from 0.085 cm3·g-1 to 0.001 3 cm3·g-1,respectively.Meanwhile,the crystal structure gradually transforms from amorphous phase into anatase and rutile phases accompanying gradual decrease of the lattice strain.The samples are composed of anatase phase with heat treatment temperature below 600 ℃,mixture of anatase and rutile phase at 600~650 ℃,and rutile phase with heat treatment temperature higher than 800 ℃.At 680~750 ℃,sodium hexatitanate is formed.
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Key words:
- nano-TiO2 /
- titanium tetrachloride /
- heat treatment /
- specific surface area /
- lattice strain
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