碳热还原法制备C/TiO2-x粉末及其电学性能研究

Synthesis and Electrical Properties of C/TiO Powders by Carbothermal Reduction

在常压条件下,以工业级偏钛酸为原料,石墨为还原剂,采用碳热还原法制备C/TiO2-x粉末。使用X射线衍射(XRD)、扫描电镜(SEM)和X射线光电子能谱(XPS)等分析手段,研究了不同还原温度和还原时间条件下还原产物的物相组成和微观结构。研究结果表明,还原温度的升高和还原时间的延长均有利于偏钛酸还原为低价钛氧化物,物相转变顺序为:偏钛酸、TiO2(金红石型)、Ti4O7和Ti3O5。SEM和XPS证实还原产物由C,O和Ti 3种元素组成,C与TiO2-x颗粒之间界面清晰,TiO2-x颗粒呈不规则形状且尺寸为3~5μm。此外,研究了还原工艺参数与还原产物电导率之间的关系,研究结果表明,影响C/TiO2-x粉末的电导率的大小的主要因素是还原产物中残留的石墨含量和Ti O2-x物相组成。在还原温度为1250℃,还原时间为20 min,配碳比为30%的条件下,还原产物碳含量为26.94%,在4 MPa和10 MPa压力下的电导率分别为8.85和15.38 S·cm-1。

Under atmospheric pressure,the C/Ti O2-x powders were prepared via the carbothermal reduction of metatitanic acid using graphite powder as the reducing agent.The phase compositions and the morphology of the as-prepared powders were investigated by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscope(SEM)in different reduction time and reduction temperature.The results showed that increasing reduction temperature and prolonging reduction time were beneficial to the reduction of metatitanic acid to low-valent titanium oxide,and the order of phase transition was metatitanic acid,TiO2(Rutile),Ti4O7 and Ti3O5.SEM and XPS results demonstrated that the reduced samples were composed of C,O and Ti,and the interface between C and TiO2-xparticles was clear.The particles of TiO2-xwere appeared irregular shape,and the particle size was 3~5μm.Moreover,the relationship between the reduction process parameters and conductivity of C/TiO2-xpowders was also studied,which showed that the electronic conductivity of C/Ti O2-xpowders was determined by the graphite content and the phase composition of TiO2-x.The carbon content of reduced products was 26.94%with carbon ratio of 30%at 1250℃for 20 min in atmospheric pressure,the electronic conductivity at pressure of 4 and 10 MPa were 8.85 and 15.38 S·cm-1,respectively.