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1.
应用磁控溅射法在以SrRuO3 (SRO)薄膜为缓冲层的Pt/TiO2/SiO2/Si(001)基片上制备了多晶BiFeO3 (BFO)薄膜,构架了SRO/BFO/SRO异质结电容器.采用X射线衍射、铁电测试仪等研究沉积温度对BFO薄膜结构和性能的影响.X射线衍射图谱显示BFO薄膜为多晶结构.在2.5 kHz测试频率下,500℃生长的BFO薄膜呈现比较饱和的电滞回线,2Pr为145μC/cm2,矫顽场Ec为158 kV/cm,漏电流密度约为2.4×104 A/cm2.漏电机制研究表明,在低电场区,SRO/BFO/SRO电容器满足欧姆导电机制,在高电场区,满足普尔-弗兰克导电机理.实验发现:SRO/BFO/SRO电容器经过109翻转后仍具有良好的抗疲劳特性. 相似文献
2.
采用磁控溅射的方法在以SrRuO3 (SRO)为底电极的(001)取向的SrTiO3基片上制备了外延BiFeO3 (BFO)薄膜,并以氧化铟锡(ITO)和金属Pt为上电极构架了ITO/BFO/SRO和Pt/BFO/SRO两种薄膜电容器,研究上电极对外延BFO薄膜铁电性和反转特性的影响.结果表明,两种薄膜电容器均体现了良好的饱和电滞回线,当测试电场为333 kV/cm时,ITO/BFO/SRO和Pt/BFO/SRO两种电容器的剩余极化强度分别为47.6 μC/cm2和56 μC/cm2,矫顽场分别为223 kV/cm和200 kV/cm.此外,两种薄膜电容器都具有良好的保持和抗疲劳特性.通过反转和非反转电流对时间的积分,可以计算出真实的极化强度.当反转电压幅值为17 V时,ITO/BFO/SRO和Pt/BFO/SRO两种电容器电流的反转时间分别为0.48 μs和0.32μs,真实极化强度的计算值约为41μC/cm2和47 μC/cm2,此计算值和铁电净极化强度的测量值符合的很好. 相似文献
3.
采用Ni-Nb薄膜作为导电阻挡层,以La0.5Sr0.5CoO3(LSCO)为底电极,构建了LSCO/Pb(Zr0.4,Ti0.6)O3(PZT)/LSCO异质结电容器。使用X射线衍射仪和铁电测试仪对其进行结构表征和性能测试。实验发现:Ni-Nb薄膜为非晶结构,PZT薄膜结晶状况良好。LSCO/PZT/LSCO电容器在5 V外加电压测试下,电滞回线具有良好的饱和趋势,剩余极化强度Pr为35.5μC/cm2,矫顽电压Vc为1.42 V,电容器具有良好的抗疲劳特性和保持特性。 相似文献
4.
采用溶胶-凝胶法在Pt/Ti/SiO2/Si基片上,制备了Pt/Pb(Zr,Ti)O3(PZT)/Pt和SrRuO3(SRO)/PZT/SrRuO3(SRO)异质结电容器,并研究了快速退火条件下SRO导电层对PZT结构和性能的影响.XRD测试表明,两种结构电容器中的PZT薄膜均为钙钛矿结构,SRO/PZT/SRO、Pt/PZT/Pt均具有较好的铁电性和脉宽依赖性,5 V电压下两电容器的剩余极化强度Pr和矫顽电压Vc分别为28.3 μC/cm2、1.2 V和17.4 μC/cm2、2.1 V.在经过1010次翻转后,SRO/PZT/SRO铁电电容器疲劳特性相对于Pt/PZT/Pt电容器有了较大的改善,但SRO导电层的引入也带来了漏电流增大的问题. 相似文献
5.
分别采用磁控溅射法和溶胶-凝胶法(Sol-gel)制备了(La0.5Sr0.5)CoO3(LSCO)和Pb(Zr1-xTix)O3(PZT)薄膜,在Pt(111)/Ti/SiO2/Si基片上构架了LSCO/Pb(Zr0.4Ti0.6)O3(PZT(40/60))/LSCO和LSCO/Pb(Zr0.2Ti0.8)O3(PZT(20/80))/LSCO铁电电容器,研究了两种铁电电容器的结构和性能。XRD结构分析表明:两种四方相的不同Zr/Ti比例的PZT薄膜均为结晶良好的多晶钙钛矿结构。在5 V测试电压下,LSCO/PZT(40/60)/LSCO和LSCO/PZT(20/80)/LSCO两种铁电电容器的剩余极化强度(Pr)和矫顽场(Ec)分别为:28μC/cm2和1.2 V以及32μC/cm2和2 V。相对于PZT(40/60),PZT(20/80)具有较大的剩余极化强度和矫顽场,是由于其矩形度(c/a)较大。两种电容器都具有较好的脉宽依赖性和抗疲劳性。在5 V的测试电压下,LSCO/PZT(40/60)/LSCO电容器的漏电流密度为3.2×10-5A/cm2,LSCO/PZT(20/80)/LSCO电容器的漏电流密度为3.11×10-4A/cm2,经拟合分析发现:在0~5 V的范围内,两种电容器都满足欧姆导电机制。 相似文献
6.
采用磁控溅射法制备SrRuO3(SRO)薄膜、脉冲激光沉积法制备BiFeO3(BFO),构架了Pt/SRO/BFO/SRO/SrTiO3(001)异质结,采用X射线衍射仪(XRD)、铁电测试仪研究了沉积温度对BFO薄膜结构和性能的影响.研究结果表明,随着温度的升高,BFO(001)和(002)衍射峰强度逐渐增强,BFO(110)和Bi2O3衍射峰强度逐渐减小,不同沉积温度下生长的样品都具有铁电性,在800 kV/cm的电场下,640 ℃下生长的BFO薄膜的剩余极化强度为65 μC/cm2.采用数学拟合的方法研究了Pt/SrRuO3/BiFeO3/SrRuO3/SrTiO3的漏电机理,结果表明BFO薄膜导电机理为普尔-弗兰克导电机理. 相似文献
7.
本文采用偏轴磁控溅射方法在Pt/TiO2/SiO2/Si(111)基片上制备了多晶BiFeO3(BFO)薄膜,并构架了Pt/BFO/Pt异质结电容器。利用X射线衍射(XRD)、铁电测试仪等手段研究了保持温度对BFO薄膜结构和性能的影响。XRD图谱表明制备的BFO薄膜均为多晶结构,在保持温度400℃±2℃的区间内得到的BFO薄膜不含明显杂相,其它的温度均有明显的杂相。在保持温度为400℃时得到了较为饱和的电滞回线,在900 nm厚度的情况下,剩余极化强度仍可以达到Pr>40μC/cm2,达到了实际应用的要求Pr>10μC/cm2。漏电流拟合机制表明在低场下属于欧姆机制,在高场下比较接近空间电荷限制电流(SCLC)机制。 相似文献
8.
应用溶胶-凝胶法在Pt/Ti/SiO2/Si(001)基片上制备了BiFeO3薄膜,构架了Pt/BiFeO3/Pt电容器.采用X射线衍射仪和铁电测试仪研究了Pt/BiFeO3/Pt电容器的结构和物理性能.实验发现BiFeO3最佳的结晶温度为600 ℃,X射线衍射图谱显示BiFeO3薄膜结晶状况良好,原子力显微镜照片显示BiFeO3表面颗粒均匀.Pt/BiFeO3/Pt电容器具有良好的电学性能,在驱动电压为5 V的情况下,Pt/BiFeO3/Pt电容器的电滞回线具有良好的对称性,漏电流密度小于10-4 A/cm2,研究发现BiFeO3薄膜log(J)/log(E)关系满足空间电荷限制电流传导机制. 相似文献
9.
采用磁控溅射法和脉冲激光沉积法,在SrTiO3(001)衬底上制备了La0.5Sr0.5CoO3(70 nm)/Pb(Zr0.4Ti0.6)O3(70 nm)/La0.5Sr0.5CoO3(70 nm) (LSCO/PZT/LSCO)铁电电容器异质结.X射线衍射结果表明:LSCO和PZT薄膜均为外延结构.在5 V的外加电压下, LSCO/PZT/LSCO电容器具有较低的矫顽电压(0.49 V),较高的剩余极化强度(41.7 μC/cm2 )和较低的漏电流密度(1.97×10-5 A/cm2),LSCO/PZT/LSCO电容器的最大介电常数为1073.漏电流的分析表明:当外加电压小于0.6 V时,电容器满足欧姆导电机制;当外加电压大于0.6 V时,符合空间电荷限制电流(SCLC)导电机制. 相似文献
10.
采用Sol-gel法和层层快速退火工艺在Pt/Ti/SiO2/Si基片上制备了厚度不同Nd掺杂的钙锶铋钛(C0.4S0.6NT)铁电薄膜.研究了单层膜厚和总膜厚对于薄膜的(200)择优取向、显微结构及铁电性能的影响.发现:恰当的单层膜厚度,有助于薄膜(200)峰的择优取向和铁电性能;单层膜厚度约为60 nm,总厚度约为420 nm时,C0.4S0.6NT薄膜的,I(200)/[I(119)+I(001)]相对强度较大,a轴取向的晶粒较多,具有较好的铁电性能,剩余极化(Pr)和矫顽场(Ec)分别为13.251μC/cm2,85.248 kV/cm. 相似文献
11.
K. Schmok 《Crystal Research and Technology》1988,23(8):967-972
The article presents an analysis into agglomeration during KCl vacuum crystallization. The theoretical and experimental investigations into the mechanism of agglomeration during mass crystallization result in an extension of the growth phenomena within the known model equations. The basis for this is essentially constituted by the collision model concepts of the theory of floculation in disperse systems. The parameters derived from the microprocess analysis (energy dissipation, content of solids, growth rate of individual grains) lead to model equations which are confirmed by laboratory and test trials. 相似文献
12.
Crystallography Reports - The relationship of morphological spectra (sets of data on the morphological types of real polyhedral crystals and their probabilities under current physicochemical... 相似文献
13.
S. S. Batsanov 《Crystallography Reports》2001,46(6):891-897
The evolution of the geometric characteristics introduced by Pauling and their dependence on the specific features of the structure and chemical bonds have been considered. The values of the covalent and van der Waals radii are given as well as their relationships and mutual transitions. 相似文献
14.
M. Szurgot 《Crystal Research and Technology》1991,26(5):555-562
The formulae for absolute Rdisap and relative R velocities of disappearance and lifetime τ of faces of growing crystals have been derived for stationary growth. It was shown that the quantities are determined by the relative growth velocity RA/RcritA of the vanishing face A with respect to the critical growth velocity RcritA and by the geometry of a crystal expressed by the trigonometric functions of interfacial angles β and γ formed between face A and the adjacent faces. R increases and τ decreases with the increase in RA/RcritA to certain limiting values. The calculations have been verified and illustrated by the experimental results for triclinic potassium bichromate (KBC) crystals. Results enable ones to predict values of velocities of disappearance and lifetimes of undesirable, supplementary faces of any real crystal. 相似文献
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16.
Measurements of thermophysical properties of Si melt and supplementary study of X-ray scattering/diffraction by the authors' group were reviewed. The values obtained differed variously from those of literature. Density was 2–3% larger, surface tension 20–30% smaller, viscosity up to 40% larger, electrical conductivity 8% smaller, spectral emissivity more or less in good agreement with literature values, and thermal diffusivity a few percent larger. An anomalous density jump was found near the melting point. Surface tension and viscosity also showed anomaly. A strange time-dependent change of density was observed over 3 h after melting. X-ray analyses suggested a slight change in local atom ordering, but showed no sign of cluster formation. An addition of 0.1 at% gallium caused the density jump to disappear, while that of boron caused no change. An EXAFS study of the former melt indicated a strong interaction between Ga and Si atoms as if molecules of GaSi3 existed. The implications of the measured properties are a possibility of soft-turbulence in an Si melt in a relatively large crucible, a more complicated manner of intake of oxygen depleted molten Si from the free surface region to underneath the growing crystal, and a relaxation of the melt after melting arising from trapped gas species. 相似文献
17.
I. Avramov 《Journal of Non》2011,357(22-23):3841-3846
The temperature dependence of viscosity of silicate melts is discussed in the framework of the Avramov–Milchev (AM) equation. The composition is described by means of two parameters: the molar fraction, x, and the “lubricant fraction”, l. The molar fraction is the sum of the molar parts xi of all oxides dissolved in SiO2, the molar fraction of the latter being 1 ? x. It is shown that, with sufficient precision, two of the parameters of the AM equation can be presented as unique functions of the molar fraction. On the other hand, x is not sufficient to determine properly the reference temperature Tr , at which viscosity is ηr = 1013 [dPa.s]. Therefore, additional parameter, “lubricant fraction” l, is introduced. For each of the components, li is a product of molar part xi and a specific dimensionless coefficient 0 ≤ ki ≤ 1 accounting for the specific contribution of this component to the increased mobility of the system. It is demonstrated that, for l > 0, the reference temperature is related to the “lubricant fraction” l through the reference temperature Tr,SiO2 of pure SiO2. 相似文献
18.
V. A. Nepochatenko 《Crystallography Reports》2004,49(5):828-831
Two types of domain-wall equations are analyzed: the equations derived by the Sapriel method and the equations obtained by interface matching of the thermal-expansion tensor. It is shown that, for W-type domain walls, these methods yield the same equations. For W′-type domain walls, the equations obtained by different methods coincide for proper ferroelastics and differ for improper ferroelastics. 相似文献
19.
Within the method of discrete modeling of packings, an algorithm of generation of possible crystal structures of heteromolecular compounds containing two or three molecules in the primitive unit cell, one of which has an arbitrary shape and the other (two others) has a shape close to spherical, is proposed. On the basis of this algorithm, a software package for personal computers is developed. This package has been approved for a number of compounds, investigated previously by X-ray diffraction analysis. The results of generation of structures of five compounds—four organic salts (with one or two spherical anions) and one solvate—are represented. 相似文献
20.
SAXS in situ experiments on the evolution of TMOS solutions during hydrolysis and polycondensation lead to power laws with scaling exponents ≈ 2. It is suggested that this could be the result of the polydispersity of the samples and that only an apparent fractal dimension can be obtained in this way. Kinetic studies tend to indicate that agglomeration in the sol is the result of a diffusion-controlled process. 相似文献