Papers by Author: De Zhong Shen

Abstract: Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) solid solutions with composition near the morphotropic phase boundary (MPB) (33mol% PT) were successfully synthesized by the molten salt synthesis (MSS) method at 800°C for 30min using Li2SO4-Na2SO4 and NaCl-KCl molten salts as a medium of reaction, respectively. The influences of processing parameters, such as temperature, time, and type of salts, on the formation and the micrographs characteristics of the PMN-PT powders were discussion. It was found that the PMN-PT powder obtained by the MSS method has a relatively uniform size distribution and a better dispersivity of particle, and an average size of PMN-PT particles with smooth surface was around 0.3∼0.5 μm. With other conditions being kept same, chloride molten salt is more propitious to the formation of PMN- PT solid solutions, and improving the compositional homogeneity of PMN-PT powders.

Abstract: Carbon nitride films were grown on Si substrates by a microwave plasma chemical vapor deposition method, using mixture of N2, CH4 and H2 as precursor. Scanning electron microscopy shows that the films consisted of a large number of hexagonal crystallites. The dimension of the largest crystallite is about 3 µm. The X-ray photoelectron spectroscopy suggests that nitrogen and carbon in the films are bonded through hybridized sp2 and sp3 configurations. The X-ray diffraction pattern indicates that the major part of the films is composed of α-, β-, pseudocubic C3N4 and graphitic C3N4. The Raman peaks match well with the calculated Raman frequencies of α- and β-C3N4, revealing the formation of the α- and β-C3N4 phase.

Abstract: Silicon carbon nitride (SiCN) films have been deposited on silicon wafers by microwave plasma chemical vapor deposition (MPCVD). Gas mixture of H2, CH4, N2, and SiH4 was used as precursors, in which the flow rate of N2 was changed. X-ray photoelectron spectroscopy (XPS) and micro-Raman spectroscopy were employed to characterize the composition and bonding structures, while field-emission scanning electron microscopy were used to investigate the microstructure of the films. With increasing the flow rate of N2 from 50 sccm to 300 sccm, the SiCN films changed from amorphous to nanocrystalline. Characteristic current-voltage measurements indicate a low turn-on field of 10.8 V/µm. Field emission current density of 4.5 mA/cm2 has been observed at 20 V/µm.