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1.
The effect of various metal electrodes on the properties of thin ferroelectric films is considered using the phenomenological Ginzburg-Landau theory. The electric field produced by charges on electrodes is taken into account (with allowance for the screening of the charges in the metals) in the free energy functional and in the Euler-Lagrange equation for the film polarization. This equation is solved using the variational method, and the free energy functional is reduced to the conventional free energy with a renormalized coefficient of P 2. This coefficient is dependent on the properties and thickness of the film and the properties of the electrode. Therefore, the physical characteristics of the size effect can be found by merely substituting the renormalized coefficient into the usual formulas from phenomenological theory. The calculations are shown to be in good agreement with the experimental data for Pt, Ir, IrO2, and SrRuO3. 相似文献
2.
M. Okuyama T. Usuki Y. Hamakawa T. Nakagawa 《Applied Physics A: Materials Science & Processing》1980,21(4):339-343
A series of experiments for growing epitaxial PLZT thin films has been made with rf sputtering. X-ray and electron diffraction
analyses confirm that the fabricated films grow epitaxially on SrTiO3 and MgO crystals. A good transparency in the region above 0.4 μm to infrared with good ferroelectric properties is obtained.
Propagation loss of He−Ne laser light is less than 6 dB/cm, and the PLZT thin film is a promising candidate for the optical
modulator and other functional elements for integrated optics. 相似文献
3.
采用金属有机物分解法在Pt/Ti/Si(111)基底上制备了退火温度分别为600℃,650℃,700℃的Bi3.15Eu0.85Ti3O12(BET)铁电薄膜,并对其结构及铁电性能进行了测试,再使用扫描探针显微镜对BET薄膜的电畴翻转进行了实时观测.BET薄膜c畴发生180°畴变的最小电压为+6V,而r畴由于其高四方性,即使极化电压增至+12V也不会发生翻转.薄膜的铁电性主要源于c畴的极化,随着退火温度的升高,c畴的区域面积增加,BET薄膜的剩余极化强度随之增大.退火温度为700℃的BET薄膜剩余极化强度达到84μC/cm2.
关键词:
铁电薄膜
电畴翻转
扫描探针显微镜 相似文献
4.
Epitaxy surface effect on the first-order phase transition properties in a ferroelectric thin film
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By modifying the interchange interactions and the transverse fields on the epitaxy surface layer,this paper studies the phase transition properties of an n-layer ferroelectric thin film by the Fermi-type Green’s function technique based on the transverse Ising model with a four-spin interaction.The special attention is given to the effect of the epitaxy surface layer on the first-order phase transition properties in the parameter space constructed by the ratios of the bulk transverse field and the bulk four-spin interaction to the bulk two-spin interaction with the framework of the higher-order decoupling approximation to the Fermi-type Green’s function.The results show that the first-order phase transition properties will be changed significantly due to the modification of interchange interaction and transverse field parameters on the epitaxy surface layer.The dependence of the first-order phase transition properties on the thickness of ferroelectric thin films is also discussed. 相似文献
5.
《Physics letters. A》2006,360(2):357-361
Using a Ginzburg–Landau–Devonshire type model, the pyroelectric property and hysteresis loop are studied for a composite ferroelectric thin film that contains an insertion of a different type of ferroelectric material in parallel connection with the host ferroelectric film material. If these two types of ferroelectric materials are polarized along the same direction, there are two peaks occur in the pyroelectric coefficient vs temperature curve. If the two ferroelectric materials are polarized in opposite directions, one positive and one negative coefficient peaks occur in the temperature dependence of pyroelectric coefficient curve and the hysteresis loop appears to be a quasi-double loop. The effect of the external electric field on the pyroelectric coefficient is also investigated. 相似文献
6.
Y. Zhou 《Solid State Communications》2010,150(29-30):1382-1385
I studied theoretically the enhancement of remanent polarization and dielectric permittivity of interfacial-coupled ferroelectric superlattices based on the Landau–Ginzburg theory. Our model adopts the Landau–Khalatnikov equation to describe hysteresis behavior and takes the time-dependent space-charge-limited conductivity into account to investigate the ferroelectric and dielectric properties of ferroelectric superlattices. The results are in good agreement with recent experimental observations on the enhancement of remanent polarization and permittivity of BaTiO3/SrTiO3 superlattices and heterolayered Pb(Zr,Ti)O3 thin films. 相似文献
7.
Z.X. Lu B.H. Teng X.H. Lu X.J. Zhang C.D. Wang 《Solid State Communications》2009,149(29-30):1176-1179
The crossover feature, from the ferroelectric-dominant phase diagram (FPD) to the paraelectric-dominant phase diagram (PPD), for the interaction parameters of a ferroelectric thin film described by the transverse Ising model have been calculated in detail by the use of the mean-field approximation. The crossover values of the exchange interactions and the transverse fields for a thin film with certain layers are displayed as a curved surface in the three-dimensional parameter space. The numerical results show that for thin films with different numbers of layers there exists a common intersection line for the curved surfaces of the crossover values. Meanwhile the layer-independent equation for the intersection line is obtained for the first time. 相似文献
8.
考虑衬底应力、畴壁运动和畴结构变化, 建立了修正的Landau-Devonshire热力学模型, 计算了生长在不同衬底上的含有纳米晶粒的PbZr0.4Ti0.6O3(PZT)薄膜的电滞回线, 研究了矫顽场、剩余极化强度和相对介电常数对晶粒尺寸以及薄膜厚度的依赖关系. 结果表明, 矫顽场和相对介电常数对晶粒尺寸的依赖关系呈类抛物线状;衬底压应力使矫顽场和剩余极化强度增大, 使相对介电常数减小;随着厚度增加, 矫顽场先缓慢增加, 到200 nm
关键词:
铁电体
晶粒尺寸
衬底应力
薄膜厚度 相似文献
9.
The dielectric properties of film materials based on polyethylene terephthalate and polycarbonate with inclusions of triglycine sulfate (TGS) and TGS with admixture of L, ??-alanine (ATGS) have been studied. An increase in the temperature of the phase transition in these materials as compared to in bulk TGS and ATGS has been revealed. 相似文献
10.
L. S. Kokhanchik 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2007,1(4):402-405
An extraordinary potential contrast of a plane domain wall forming in the case of excess negative charging of a ferroelastic-ferroelectric Tb2(MoO4)3 sample with a two-domain structure has been detected using a scanning electron microscope. Conditions and features of the formation of this potential contrast (called charge contrast) in the domain wall region are determined. It is shown that the surface is charged at a lower rate in the domain wall region, which is an elastically strained crystal region. The smallest domain wall width determined by the charge-contrast image was 1.6 μm on the average. 相似文献
11.
Thermal heating/cooling conditions for metal-insulator-metal structures based on barium strontium titanate ferroelectric films are studied by numerical methods with the aim of their application in capacitive thermoelectric converters. A correlation between the thermal and capacitive properties of thin-film ferroelectric capacitors is considered. The time of the temperature response and the rate of variation of the capacitive properties of the metal-insulator-metal structures are determined by analyzing the dynamics of thermal processes. Thermophysical calculations are carried out that take into consideration the real electrical properties of barium strontium titanate ferroelectric films and allow estimation of thermal modulation parameters and the efficiency of capacitive thermoelectric converters on their basis. 相似文献
12.
13.
Combined effect of the transition layer and interfacial coupling on the properties of ferroelectric bilayer film
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Within the framework of modified Ginzburg--Landau--Devonshire
phenomenological theory, a ferroelectric bilayer film with a
transition layer within each constituent film and an interfacial
coupling between two materials has been studied. Properties
including the Curie temperature and the spontaneous polarization of
a bilayer film composed of two equally thick ferroelectric
constituent films are discussed. The results show that the combined
effect of the transition layer and the interfacial coupling plays an
important role in explaining the interesting behaviour of
ferroelectric multilayer structures consisting of two ferroelectric
materials. 相似文献
14.
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16.
Mechanisms of static deformation of a freely suspended ferroelectric smectic (C*) film in an external transverse electric field are analyzed. An equation for the shape of the film that includes the interaction
of the applied field with the polarization vector and surface charges is derived in terms of the variational approach. The
effect of deformation is shown to be of threshold character, which agrees with the experimental data. 相似文献
17.
We study the influence of the surface of the ferroelectric films on the properties of the intrinsic ferroelectric polarization state in frame of statistical Transverse Ising Model (TIM). The quality of the surface is modelled by the dilution parameter q that reflects the relative weight of the paraelectric impurities vs. ferroelectric ions. Using the effective field approach the variation of the average value of spontaneous polarization as function of temperature for different film thicknesses has been investigated as function of dilution parameter q. The phase diagram of the system and crossover from the ferroelectric to the paraelectric phase is discussed. 相似文献
18.
《Physica A》2013,392(17):3570-3577
19.
Using the Landau–Khalatnikov equation of motion, the polarization reversal behavior in an asymmetric ferroelectric thin film has been studied. Our model first introduces a third power of polarization to describe the asymmetry of a ferroelectric thin film with surface transition layer, which originates from the difference between the surfaces. Interestingly, vertical drift of polarization switching behaviors was found in this system. The properties consisting of hysteresis loop, spontaneous polarization, switching current of an asymmetric ferroelectric thin film with surface transition layer are discussed. 相似文献
20.
M. S. Ivanov A. M. Buryakov V. G. Morozov E. D. Mishina A. S. Sigov 《Physics of the Solid State》2014,56(6):1144-1149
This paper presents the results of an experimental investigation of current flow through a ferroelectric nanolayer in a series of bilayer ferroelectric/manganite structures prepared by metalorganic aerosol deposition on a MgO substrate. It has been shown that a variation in the thickness of the ferroelectric layer in a bilayer ferroelectric/manganite structure leads to a change in the metal-insulator phase transition temperature of the manganite layer and also affects the transport properties of the ferroelectric/manganite structure. Based on the analysis of the experimental results, it is demonstrated that the ferroelectric layer up to 4 nm thick exhibits polarization properties. In the theoretical analysis, it is assumed that electrical conduction of bilayer structures is provided by a dual mechanism combining the electron tunneling through a ferroelectric barrier and the ohmic current flow in a manganite layer. The possibility of retaining the mechanism of charge carrier tunneling in a bilayer ferroelectric/manganite structure through the ferroelectric layer up to 6 nm thick is discussed. 相似文献