Papers by Author: Jiang Li Cao

Abstract: Effects of additives on the semiconduction transformation of lead zirconate titanate (PZT) during atomic hydrogen charging were investigated. The results showed that the resistivity of the samples decreased by seven orders of magnitude with sixty hours of hydrogen charging in electrolytic without additives. Then with further increasing hydrogen charging time, the resistivity decreased continually, however, much more slowly. Scanning electron microscopy (SEM) showed that the surface structures of PZT were changed significantly upon atomic hydrogen charging. Sodium pyrophosphate (Na₄P₂O₇) and Na₂EDTA could effectively affect the semiconduction transformation of PZT as well as the surface structure change. Transmission electron microscopy (TEM) and XRD analysis indicated that there was no new substance formed on the surface of PZT upon atomic hydrogen charging.

Abstract: The structural origin of imprint in Pb(Zr,Ti)O₃ (PZT) ferroelectric thin films derived by chemical solution deposition with Pt top and bottom electrodes was studied by in-situ high-resolution X-ray specular reflectivity of synchrotron radiation. Global structural parameters of density, thickness, and surface or interface roughness of each component layer in the thin film sample were obtained. No generation of interfacial layers with a different electron density from PZT and no interface roughening were observed at the interfaces of PZT and Pt during imprint. Thus, the results suggest that the imprint effect is more likely a bulk or electronic defects-related phenomenon.

Abstract: The yttria-erbia multilayered coatings were prepared on 316L stainless steel substrates by bipolar pulse magnetron sputtering. Structures of these coatings were examined by X-ray diffraction and scanning electron microscopy. Bonding strength of these coatings on 316L stainless steel substrates was measured by scratch tester. Nano-hardness of these coatings was measured by nano-indenter. Comparative studies of the mechanical properties of the single-layered yttria coatings and multilayered coatings were conducted, and the seven layered coatings presented the highest bonding strength and nano-hardness as well as elastic modulus.

Abstract: Y₂O₃/YO_x composite coatings with different YO_x adhesion layers were fabricated on 316L stainless steel substrates through reactive magnetron sputtering. The YO_x adhesion layers were deposited by radio frequency reactive magnetron sputtering with different oxygen partial pressures at a total pressure of 1.2 Pa. The Y₂O₃ coatings were deposited by bipolar pulse reactive magnetron sputtering. The relationships between the microstructures, phase compositions, interfacial adhesion of the composite coatings and the oxygen partial pressure used for deposition of the YO_x adhesion layers were investigated. The microstructures and phase compositions of the coatings were characterized by scanning electronic microscopy and X-ray diffraction. The bonding strength of the coatings was measured by scratch tester. The results showed that the bonding strength of the Y₂O₃/YO_x composite coatings reached the maximum value when the oxygen partial pressure was 0.18 Pa.