Chen-Fu Lin

Enhanced ferromagnetism in grain boundary of Co-doped ZnO films: A magnetic force microscopy study

Microscopic grain structures and magnetic properties of Co-doped ZnO-patterned films were studied by combinatorial atomic force microscopy and magnetic force microscopy (MFM) imaging. Whereas Co-doped ZnO was not uniformly magnetized, Co ions were homogeneously doped in the films and substitute from the Zn sites. Most Co:ZnO grains were weakly ferromagnetic (FM) and surrounded by strong FM foamlike grain boundaries networks. No MFM contrast was observed in pure ZnO films grown under similar conditions. The findings clearly demonstrate that defective grain boundaries and magnetic doping have key roles FM properties of diluted magnetic oxides.

Influence of superlattice and antiphase domain boundaries on dielectric loss in Ba[Mg1∕3(Nbx∕4Ta(4−x)∕4)2∕3]O3 ceramics

The Ba[Mg1∕3(Nbx∕4Ta(4−x)∕4)2∕3]O3 ceramics (x=0, 1, 2, 3, and 4) synthesized by a solid reaction method were sintered at 1650u2009°C for 9 h. The quality factor (Q,∼1∕tanδ,tanδ: dielectric loss) and superlattice structure were investigated by the cavity method and high-resolution electron microscopy. The excellent Q value of 17u2009600 obtained at appropriate Nb content (x=1). The disorder structure (superlattice modulation∼0.41nm), 1:2 ordering structure (superlattice modulation∼0.71nm) and antiphase domain boundary (APB) were revealed in Ba[Mg1∕3(Nbx∕4Ta(4−x)∕4)2∕3]O3 ceramics. The formation of extra ordering structure (superlattice modulation∼1.24nm) on the APBs contributed to the improved Q value with the stabilization of ordering-induced domain boundaries.

EFFECT OF THE HEATING RATE FOR PREHEATING PROCESS ON THE COMPOSITION AND PHASE TRANSFORMATION OF SOL-GEL DERIVED LEAD ZIRCONATE TITANATE THIN FILM

ABSTRACT Lead zirconate titanate (PZT, 53/47) thin firms were successfully fabricated on multi-layers substrate by the spin-coating sol-gel process. The effects of different heating rates on the composition and phase transformation of PZT films were discussed. This study focused on the slow heating rate (1°C/min) to the first preheating step (150°C) and to second pyrolysis step (350°C). By XRD method, PZT films contained entirely pure perovskite phase annealing at 700°C for 30 min for the slow heating rate procedure. By using EPMA analysis, the composition of PZT thin film derived by this procedure was indeed located at the MPB region. Furthermore, the phase coexistence was evidenced by the BEI analysis.

Effects of PVA Adding on the Microstructure and Composition of Sol-Gel Derived PZT Films

ABSTRACT Lead zirconate titanate (PZT, 53/47) films were successfully fabricated on multi-layers substrate (Pt/Ti/SiO2/Si) by the spin-coating via sol-gel process. A special core-shell structure was formed in the films by the adding of PVA polymer. XRD results showed that PZT films transform to pure perovskite phase entirely after annealing at 700°C for 90 min. By EPMA analysis, the composition of PZT thin film derived by this procedure was located at the morphotrophic phase boundary (MPB) region. Furthermore, the composition variations in the core-shell structure were identified by the backscattering electron image (BEI) analysis. With this innovative procedure, crack-free PZT films were successfully obtained.