Investigation on Processing and Properties for Nb2O5 doped PZT Targets and Thin Films
Date Issued
2005
Date
2005
Author(s)
Meng, Chin-Hau
DOI
en-US
Abstract
Processing and properties for the preparation of Nb doped PZT targets and thin films were investigated. The microstructural related electrical properties were determined in this research. The PZT or PNZT bulk materials were fabricated by colloid processes in which the ceramic powders had to be dispersed into particular solvents. In order to prevent the dissolution of Pb species dissolving from PZT powder in aqueous dispersion systems, several organic dispersion systems were used. From the analysis of atomic absorbance spectroscopy, centrifugal sedimentation and ζ-potential, 0.6 wt% KD4 added toluene was an optimum dispersion system for PZT and Nb2O5 powders. SEM and XRD were used to analyze the microstructure and crystalline phase of PZT and PNZT bulk materials. The solubility limit of Nb in PZT were found to be 5 mol% in this research. The grain sizes of PNZT decreased as the Nb concentration below 4.7 mol%, while contrary trend could be noted at the doping concentrations higher than this value. It was found that the amount of Nb doping, could reduce the value of coercive field. Otherwise, the existence of pyrochlore phase and inhibited grain sizes would cause the value of d33，d31，Kp and Pr decreasing.
The PZT and PNZT thin film materials were deposited on Pt/Ti/Si at ambient temperature by ion beam sputtering deposition (IBSD) and the annealing temperatures, 600 and 700 oC were chosen. XRD, AFM, SEM, and TEM were used to analyzed film thickness, crystal phase, Nb content and microstructure. The results shown that the annealing temperature should be 700 oC was good for PZT thin film to crystallize into pervoskite phase, while for PNZT thin film, second phases (pyrochlore) were existed. After full quantification of PNZT film by EDS, the Nb content was about 8.63 mol% which was higher than the solubility limit of Nb in PZT material. From TEM results, the grain sizes of PZT thin film were about 2 μm with an (110) preferred orientation. As for PNZT thin film, grain sizes in equiaxial were about 1 μm with randomly orientation. Porosity was noted inside these films and the discontinuities of Pt electrode were occasionally seen in PZT and PNZT thin films. The results of D-E loops for both PZT and PNZT thin film revealed lower Pr and higher Ec by comparing with the commonly observed value, 30-70 C/m2, though the grain sizes were larger and the crystal phases were pervoskite phase. This degraded polarization behavior of PZT and PNZT thin films, the same as that observed in PZT and PNZT bulk materials, should be caused by the existence of pores and the other structural features in both films.
Subjects
氧化鈮
鋯鈦酸鉛
zeta電位
鉛溶出
靶材
薄膜
離子束濺鍍法
Niobium
PZT
Zeta potential
Pb dissolution
target
thin film
IBSD
Type
thesis
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