XPS study of (V_90.995)Al_(0.005)_2O_3 PTC ceramics

摘要

The theory and experimental research of metal-insulator transition for (Vi_,vAv)2O3 system ceramics and crystal materials has been the subject of numerous investigations for a long time [1-4]. In particular, the positive temperature coefficient (PTC) transition above room temperature appearing mainly in (V1_TAT)2O3 ceramics has become a very interesting phenomenon [5-8]. Our preliminary study showed that an obvious PTC effect also existed in (Vi _,VAJ.)2O3 ceramics and their PTC properties were closely related to the liquid nitrogen treating process. In this letter the valence band X-ray photoelectron spectroscopy (XPS) spectra of untreated and liquid nitrogen treated samples are reported. From these results, together with the results of X-ray diffraction (XRD) phase structure analysis and resistivity-temperature property measurement, the effect of liquid nitrogen treatment on material properties is discussed.