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从Landau-Devonshire唯象理论出发,考虑到晶格失配导致的位错应力场与极化场的耦合,研究了在SrTiO3衬底上外延生长的PbZr0.4Ti0.6O3薄膜厚度对其自发极化强度、电滞回线的影响.结果表明,产生位错的PbZr0.4Ti0.6O3薄膜临界厚度为～1.27nm,当薄膜厚度大于临界厚度时,在所形成的位错附近,极化强度出现急剧变化,形成自发极化强度明显减弱的“死层”;随着薄膜厚度的减小,位错间距增大,“死层”厚度与薄膜总厚度之比增加.由薄膜电滞回线的变化情况可知,其剩余极化强度随着薄膜厚度的减小而逐渐减小.
Based on Landau-Devonshire phenomenological theory, taking into account the coupling of the stress-strain field and the polarization field caused by lattice mismatch, the effect of the thickness of PbZr0.4Ti0.6O3 thin film epitaxially grown on the SrTiO3 substrate on its spontaneous The results show that the critical thickness of PbZr0.4Ti0.6O3 thin film is ~ 1.27nm. When the film thickness is larger than the critical thickness, near the dislocations formed, the polarization intensity With the sharp change of the spontaneous polarization intensity of the formation of the “dead layer”; With the decrease of the film thickness, dislocation spacing increases, the ratio of “dead layer” to the total film thickness increased by the film hysteresis loop Changes in the situation shows that the residual polarization intensity decreases with the film thickness decreases.