煅烧温度对ATO/TiO_2粉体表面晶化及电导率的影响

用湿化学法在TiO2颗粒表面包覆ATO制得ATO/TiO2复合导电粉;运用TG-DSC、XRD、XPS、SEM、和电导率测试等手段对ATO/TiO2导电粉进行了表征.结果表明：煅烧温度对SnO2的晶化程度、Sb的价态、ATO/TiO2导电粉的导电性产生影响.电导率-温度（lnσ-T）关系呈抛物线（100～900℃）：上坡段（150～400℃）,温度增加,无定形SnO2逐渐晶化,电导率增加,导电性上升,溶入SnO2的Sb3＋→Sb5＋转变,载流子浓度加大,包膜层多孔结构逐渐致密化;底部平台（400～600℃）,SnO2晶化结束,Sb3＋→Sb5＋转变趋于完成,电子散射趋于最低,电导率最大,导电性达到最佳;下坡段（600～900℃）,Sb3＋→Sb5＋转变发生逆转,TiO2基体颗粒长大,锐态型向金红石型转变,破坏包膜结构,电导率上升,导电性恶化.

Effect of calcination temperature on surface crystallization and conductivity of ATO/TiO_2 composite conductive powder

ATO/TiO2 coated by Sb-doped SnO2,and conductive composite powders were prepared by wet chemical method.ATO/TiO2 conductive composite powders were characterized by differential thermal-differential scanning calorimetry（TG-DSC）,X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,scanning electron microscopy（SEM） and conductivity test.The research results were the influence of the calcination temperature on the SnO2 crystallization degree,the Sb valence,the conductivity of the ATO/TiO2 conductive powder were found.Resistivity-temperature（ρ-T） relations was the U-curve（100—900 ℃）.During the uphill（150—400 ℃）,temperature increased,amorphous SnO2 crystallized gradually,and the conductivity increased,Sb3＋ Sb5＋,carrier concentration increased,the porous structure of coating layer gradually densed;during the platform at the bottom（400—600 ℃）,the crystallization of SnO2 ended up,Sb3＋ Sb5＋ change tended to completion,electron scattering tends to a minimum,the resistivity was the lowest,the conductivity was optical.During the downhill sections（600—900 ℃）,Sb3＋ Sb5＋ change reversed,TiO2 matrix particles grow up sharply,the acute-type tended to rutile-type changes,the coated structure was damaged,the resistivity increased,the conductivity deteriorated.