Sue Hao

Effects of the penetration temperature on structure and electrical conductivity of samarium modified BaTiO3 powders

Abstract Gaseous penetration technique was adopted to improve the electrical conductivity of BaTiO3 powders and the effects of penetration temperature on the structure and electrical conductivity of Sm-modified BaTiO3 powders were studied. It was observed that the penetration of Sm made the resistivity of BaTiO3 powders decrease with the increase in the penetration temperature and decreased to the lowest point of 4.20×102 Ω·m when the penetration temperature was 950 °C. The relationship curve of the temperature and resistivity of the samples was also established preliminarily to get the mathematical expression by the fitting method. Through X-ray diffraction (XRD) analysis, the new phases of Sm2O3 and Ba4Ti2O27 were detected. It was indicated that intricate reactions related to Sm took place during the penetration process and led to the Ti-rich state of the system. The Fourier transform infrared (FTIR) spectrum illustrated that the bonds of Ti–O octahedron was strengthened by substitution of Sm3+ at Ti4+ sites, which led to the growth of Ti: Ba ratio. The analysis results of scanning electron microscopy (SEM) indicated that the particle size of Sm-modified BaTiO3 powders progressed with the penetration temperature increasing.

Investigation on constitution of electrical conductive adhesives fitting for UV–thermal dual curing

In order to meet the requirements of environment protection and energy conservation, we propose to prepare electrical conductive adhesives (ECAs) fitting for UV–thermal dual curing and to investigate the constitution of the ECAs. Based on the determination of the mixture ratio of epoxy resin-44 (E-44) and unsaturated polyester resin (UP), the dosage of 3-Amino-propyl-triethoxy-silane (KH-550), thinner, thermal curing agent, accelerating agent, light-initiator agent, and the conductive filler of the ECAs was determined. The prepared films after UV–thermal dual curing were analyzed by Fourier transform infrared spectrometer and thermogravimetric analyzer to characterize their constitution and thermal properties. The best prescription of ECAs was obtained as follows: the ratio of E-44 and UP is 0.5:1, KH-550 is 6%, thinner is 8%, thermal curing agent is 7.5%, accelerating agent is 7.5%, light-initiator agent is 6%, and the conductive filler is 60%. Under these conditions, the prepared ECAs have cross-linked net structure and good thermal stability. Their properties are applicable as follows: the hardness is 6H; the tensile strength is 95.12 MPa; the volume resistivity is 4.75 Ω cm; the gel content is 93.37%; the water absorption ratio is 5.81%; and the stability is more than 180 days.

Modification of Ag-doped BaTiO3 powders through La gaseous penetration route

Abstract The Ag-doped BaTiO 3 (BATO) polycrystalline powders were fabricated by Sol-Gel method. Further modification by rare earth La was done through gaseous penetration route. Changes in constitution, structure, and electrical conductivity before and after modification of Ag and La were characterized. The acceptor dopant Ag owned the ability to decrease the resistivity of the doping samples from 4.30×10 9 Ω·m to 6.14×10 5 Ω·m where the resistivity fell by 4 orders of magnitude when the Ag doping ratio was 0.10%. And more doping of Ag enhanced the resistivity dramatically even beyond 2.0×10 7 Ω·m. Yet, gaseous penetration of La successively reduced the resistivity of BATO to the lowest point of 2.45×10 5 Ω·m. XRD analysis indicated that the doping process of Ag did not change the perovskite structure and main phases of the powders. However, new compound BaLa 2 O 4 generated from complex reactions during the penetration process, which manifested that La 3+ penetrated into the crystal lattices in the form of substituting the Ti 4+ site. And this substitution strengthened the Ti-O bond, which led to the inhibition of blue shift in FTIR spectrum caused by doping of Ag. The morphology of La penetrated BATO powders detected by SEM and EDAX suggested that La did penetrate into the powders and this penetration process progressed the partly sintering of the powders which is in favor of the conductivity.

Fabrication and properties of La modified AZO powders via a gaseous penetration processing

Abstract A new kind of AZO powders were synthesized by co-precipitation method with the doping content of Al was 3.0 wt%. Further modification of La to the powders was done via a gaseous penetration processing. Changes in constitution, structure, and electrical conductivity caused by doping and penetration were characterized. The doping of Al lowered the resistivity of AZO powders from over 1×10 14 (ZnO made domestically) to 4.24×10 7 Ω·cm. But more effective modification via gaseous penetration processing decreased the resistivity of La penetrated AZO powders to the lowest point of 2.45×10 5 Ω·cm. The optimal penetration conditions coordinated by orthogonal test were that La 3+ content of the penetration solvent was 2.0 wt.%, and that the penetration processing lasted for 5 h at the temperature of 480 °C. XRD analysis demonstrated that the doping process of Al only leaded to the changes of the peak width and intensity without new phases appearing. Yet, new phases appeared after the processing of gaseous penetration of La, which indicated that La enter the AZO powders thus complex reactions occurred to form the extra compounds. EDAX analysis, coupling with XRD, provided the evidence that La did exist in the penetrated AZO powders and the potential sign of the generation of extra compounds. Through SEM images, it was illustrated that the gaseous penetration processing progressed the growth of grain size in the shape of rod and generated distinguishable phases of extra compounds.