The diffusion of Pt in BST films on Pt/Ti/SiO2/Si substrate by sol-gel method

Barium strontium titanate (Ba_0.65Sr_0.35TiO₃) ferroelectric thin films have been prepared by sol-gel method on Pt/Ti/SiO₂/Si substrate. The X-ray diffraction (XRD) pattern indicated that the films were a polycrystalline perovskite structure and the atomic force microscope (AFM) image showed that the crystallite size and the root mean square roughness (RMS) were 90 nm and 3.6 nm, respectively. The X-ray photoelectron spectrum (XPS) images showed that Pt consisting in BST thin films was the metallic state, and the Auger electron spectroscopy (AES) analysed the Pt concentration in different depth profiles of BST thin films. The result displayed that the Pt diffusion in BST thin film is divided into two regions: near the BST/Pt interface, the diffusion type was volume diffusion, and far from the interface correspondingly, the diffusion type became grain boundary diffusion. In this paper, the previous researcher’s result was used to verify our conclusion.     

Influence of YSZ buffer layer on the electric properties of compositionally graded (Ba,Sr)TiO<Subscript>3</Subscript> thin film

Compositionally graded Ba_1−x Sr _x TiO₃ (BST) (0 ≤ x ≤ 0.4) thin films were fabricated on Pt/Ti/SiO₂/Si and YSZ/Pt/Ti/SiO₂/Si substrates by a modified sol–gel technique. The YSZ buffer layer was prepared by RF magnetron sputtering. The microstructure of the graded BST films was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The results showed that all the films have uniform and crack-free surface with a perovskite structure. The graded BST film with an YSZ buffer layer has larger dielectric constant and lower dielectric loss. The leakage current density of the graded BST film with an YSZ buffer layer lowers two orders than the film without buffer layer. The improved electric properties of the graded films with an YSZ buffer layer was attributed to the YSZ buffer layer act as an excellent seeding layer to enhance the graded BST film growth.     

Preparation and Refractive Index of Nano BST Thin Films

"Radio frequency magnetron sputtering technique is used to deposit Ba0:65Sr0:35TiO3 (BST) thin films on fused quartz substrates. In order to prepare the high quality BST thin films, the crystallization and microstructure of the films were characterized by X-ray diffraction, field emission scanning electron microscopy and atom force microstructure. The more intense characteristic diffraction peaks and better crystallization can be observed in BST thin films deposited at 600 oC and subsequently annealed at 700 oC. The refractive index of the films is determined from the measured transmission spectra. The dependences of the refractive index on the deposition parameters of BST thin films are different. The refractive index of the films increases with the substrate temperature. At lower sputtering pressure, the refractive index increases from 1.797 to 2.179 with the pressure increase. However, when the pressure increases up to 3.9 Pa, the refractive index instead reduces to 1.860. The oxygen to argon ratio also plays an important effect on the refractive index of the films. It has been found that the refractive index increases with the ratio of oxygen to argon increasing. The refractive index of BST thin films is strongly dependent on the annealing temperature, which also increases as the annealing temperature ascends. In one word, the refractive index of BST thin films is finally affected by the films microstructure and texture."     

Zn-Induced Interactions Between SARS-CoV-2 orf7a and BST2/Tetherin

We present in this work a first X-ray Absorption Spectroscopy study of the interactions of Zn with human BST2/tetherin and SARS-CoV-2 orf7a proteins as well as with some of their complexes. The analysis of the XANES region of the measured spectra shows that Zn binds to BST2, as well as to orf7a, thus resulting in the formation of BST2-orf7a complexes. This structural information confirms the the conjecture, recently put forward by some of the present Authors, according to which the accessory orf7a (and possibly also orf8) viral protein are capable of interfering with the BST2 antiviral activity. Our explanation for this behavior is that, when BST2 gets in contact with Zn bound to the orf7a Cys₁₅ ligand, it has the ability of displacing the metal owing to the creation of a new disulfide bridge across the two proteins. The formation of this BST2-orf7a complex destabilizes BST2 dimerization, thus impairing the antiviral activity of the latter.     

Neo-Pentoxide Precursor Synthesis,Solution Preparation,and Electronic Properties of (Ba,Sr)TiO3 Thin Films Derived from a Solution Route

We have recently isolated the neo-pentoxide (HOCH₂CMe₃, ONp) derivatives of Ba, Sr, and Ti as Ba₄(ONp)₈(HONp)₆(py)₂, Sr₅(O)(ONp)₈(Solv)₅ (Solv = solvent), and Ti₂(ONp)₈, respectively. The combination of these precursors were found to be readily soluble in a wide range of solvents and thus were excellent candidates for preparation of barium strontium titanate ((Ba,Sr)TiO₃ or BST) thin films using spin-cast deposition techniques. The highest quality BST films for this system were generated from ternary mixtures dissolved in either pyridine or pyridine/toluene. By in situ VT-GIXRD analysis it was determined that the perovskite phase of BST was readily formed at 650°C. The electronic properties of films crystallized at 700°C indicated that the thin films (300 nm) possessed a dielectric constant of 120 (tan = 0.03) with a tunability of 29% at ±10 V. 300 nm films (700°C) which had been generated from a standard BST solution modified with a novel tridentate ligand, had a higher dielectric constant of 180 and a tunability of 35% at ±10 V. The collective characteristics of these precursors offer an attractive alternative to the more complex, less stable sol-gel precursors currently in use.     

BST和BZT系列固溶体的均相沉淀法合成及表征

采用均相沉淀法, 在低温(90 ℃)、低pH值(8～9)、短时间(3～3.5 h)条件下成功地合成了系列Ba_1－xSr_xTiO₃ (BST)和BaZr_xTi_1－xO₃ (BZT)固溶体. 通过XRD、化学分析法、SEM和AFM等手段表征了固溶体的结构、组成和形貌. 结果表明: BST, BZT的晶胞常数随组成呈线性关系, 符合Vegard定律, 该系列固溶体为完全互溶固溶体, 且目标产物组成精确, 颗粒为球形, 分布均匀. 初步讨论了复合矿化剂的均相化作用及羟基释放作用、分散剂对BST, BZT晶粒的聚集生长及分散机理.     

BST/Si-NPA复合薄膜的湿敏电容特性研究

本文采用溶胶-凝胶法和旋涂工艺，以Si-NPA为衬底，制备了钛酸锶钡(BST)/Si-NPA复合薄膜，并对其形貌、结构及湿敏电容特性进行了研究。结果表明，环境的相对湿度(RH)、测试信号频率和退火温度均对湿敏电容特性具有较大影响。在100 Hz的测试信号频率下，当环境的相对湿度从11%上升到95%时，BST/Si-NPA湿敏元件的电容增量可达起始值的4 400%，显示出较高的湿度敏感性。同时，元件的响应时间和恢复时间均约为42 s，表现出较快的时间响应和均衡的吸附/脱附。最后，通过复阻抗法讨论了元件的感湿机理。     

High performance distributed CPW phase shifters with etched BST thin films on Ф 3″ LaAlO3 substrates

The design, fabrication and microwave properties of distributed coplanar waveguide (CPW) phase shifters using etched Ba_0.6Sr_0.4TiO₃ (BST) thin films on Ф 3″ LaAlO₃ (100) substrates were investigated. The BST thin films employed in the circuits are deposited by RF magnetron sputtering, and then annealed at 800 °C for 30 min in air. BST thin films parallel-plate capacitors were fabricated by photolithography and etching process. At 10 kHz and 600 kV/cm electric field, the dielectric tunability, remanent polarization (2P_r) and the coercive electric field (2E_C) of BST film were 28.7%, 2.265 μC/cm² and 38.8 kV/cm, respectively. The loss tangent was 0.005 at zero electric field. The CPW phase-shifter designed was subsequently fabricated by optimum BST thin films and thickened top electrodes. At 21.3 GHz and 35 V, 360° phase shift was achieved, the insertion loss was −8.5 dB, the ?gure-of-merit (FOM) was 42.4°/dB, and the return loss was −12.1 dB.     

原位制备钛酸锶钡/铌酸锶钡复相陶瓷的研究

0引言驰豫型铁电陶瓷是近年来广泛研究和迅速发展的一种新型功能陶瓷[1]。通过把具有不同相变温度的驰豫型铁电体层层叠加,可以获得具有稳定的介电常数鄄温度关系的复合材料[2]。钛酸锶钡Ba1-xSrxTiO3和铌酸锶钡SrxBa1-xNb2O6都是重要的驰豫型铁电体,并且其居里温度均随Ba/Sr比     

Facile preparation of vanadium oxide thin films on sapphire(0001) by sol–gel method

The Ba_0.6Sr_0.4TiO₃ (BST60) thin films were deposited on Pt(111)/Ti/SiO₂/Si(100) substrates by a sol–gel method. The thickness of CeO₂, serving as a buffer layer, was varied from 0 to 75 nm, in order to optimize the dielectric tunable property. X-ray patterns analysis indicates that all the thin films exhibit good crystalline quality with a pure perovskite phase and insertion of the CeO₂ buffer layer does not change the crystal structure of BST60. Dielectric properties of the thin films were investigated as a function of both temperature and direct current electric field. The results show that dielectric constant and loss are modified by insertion of the CeO₂ buffer layer. The BST60 thin films with 25 nm thickness CeO₂ buffer layer have the highest figure of merit, low dielectric loss, and suitable dielectric constant, which render them attractive for the tunable microwave device applications.     

Significant suppression of leakage current in (Ba x ,Sr1-x )TiO3/MgO heterostructured thin films by thin MgO layers insertion

The leakage behavior and dielectric property of BST80/MgO heterostructured thin films deposited on LaNiO₃ (LNO)/Si substrates by sol-gel were investigated. The dielectric constant and the leakage current are modified by MgO insertion. The dramatic reduction in the leakage current effectively increased the charge retention of the capacitors consisted of heterostructured thin films as compared to the pure BST films. The significant reduction in the leakage current can be attributed to the minute solid solubility of MgO in the BST lattice and the potential barrier built in the interface between BST and MgO layers in the heterostructured thin films.     

离子液体电沉积CuInxGa1-xSe2薄膜

采用循环伏安法(CV)对离子液体Reline中三元CuCl₂+InCl₃+SeCl₄体系和四元CuCl₂+InCl₃+GaCl₃+SeCl₄体系的电化学行为进行了研究。研究表明,In³⁺并入三元CIS(Cu-In-Se)薄膜体系和Ga³⁺并入四元CIGS(Cu-In-Ga-Se)薄膜体系均有两种途径：一是发生共沉积,二是直接还原。利用电感耦合等离子体发射光谱(ICP)和扫描电镜(SEM)对沉积电势、镀液温度和主盐浓度对CIGS薄膜组成、镀层表面形貌的影响进行了测试,结果表明通过工艺参数的选择可以控制Ga/(Ga+In)和CIGS薄膜组成并得到化学计量比为Cu_1.00In_0.78Ga_0.27Se_2.13的薄膜。     

Ba Titanate and Barium/Strontium Titanate Thin Films from Hydroxide Precursors: Preparation and Ferroelectric Behavior

Randomly oriented ferroelectric BaTiO₃ and (Ba_0.6Sr_0.4) TiO₃ thin films on platinum coated Si (100) were prepared by a sol-gel method. The precursor solutions were derived from barium hydroxide or a mixture of barium/strontium hydroxides dissolved in acetic acid and titanium butoxide. Polarization versus applied voltage hysteresis studies indicated a remanent polarization of 3 µC/cm² and a coercive field of 43.4 kV/cm for BaTiO₃ films annealed at 800°C for 1 h. Corresponding parameters for (Ba_0.6Sr_0.4)TiO₃ films annealed at 800°C were found to be 7.2 µC/cm² and 102.7 kV/cm, respectively. Microstructural study of the surface morphology of these films indicated grains of less than 0.1 µm in size. The leakage current for (Ba_0.6Sr_0.4)TiO₃ films was found to be two orders of magnitude lower than that for BaTiO₃ films.     

室温电化学沉积Ba1-xCaxMoO4多晶固溶体薄膜

近年发展起来的制备功能薄膜的电化学沉积技术,是软溶液工艺路线(Soft Solution Processing简记为SSP)中的重要技术[1]。与传统的薄膜制备技术相比,电化学沉积技术在反应控制、形貌控制、沉积速度、能量消耗、环境影响、薄膜晶化以及沉积设备等方面都有较明显的优势,同时避免了     

Microstructure and ferroelectric properties of r.f. magnetron sputtering derived PZT thin films deposited on interlayer (PbO/TiO2)

Lead zirconate titanate (PZT) thin films were deposited on Pt/Ti/SiO₂/Si and interlayer/Pt/Ti/SiO₂/Si substrate by radio frequency (r.f.) magnetron sputtering with a Pb_1.1Zr_0.53Ti_0.47O₃ target. The crystallization of the PZT thin films was formed only by substrate temperature. When interlayer (PbO/TiO₂) was inserted between the PZT thin film and the Pt electrode, the grain growth and processing temperature of the PZT thin films were considerably improved. Compared to PZT/Pt structure, the dielectric constant and polarization properties of the PZT/interlayer/Pt structure were fairly improved. In particular, PZT/interlayer/Pt at the substrate temperature of 400 °C showed prevalent ferroelectric properties (_r=475.97, tanδ=0.0591, P_r=23 μC/cm²). As a result of an X-ray photoelectron spectroscopy (XPS) depth-profile analysis, it was found that PZT/interlayer/Pt deposited only by substrate temperature without the post-annealing process via r.f. magnetron sputtering method remained independent of each other regardless of substrate temperatures.     

Ba0.6Sr0.4TiO3/聚偏氟乙烯-聚甲基丙烯酸甲酯复合材料的制备及其介电性能

采用流延热压工艺制备Ba_0.6Sr_0.4TiO₃(BST)/聚偏氟乙烯(PVDF)?聚甲基丙烯酸甲酯(PMMA)复合薄膜,研究了PMMA含量对复合材料微观组织结构和介电性能的影响规律。结果表明,BST相能够均匀分散在聚合物基体中,归因于PMMA与PVDF良好的相容性,2种聚合物之间的界面不分明;随着PMMA含量的增加,复合材料的介电常数先降低后升高,耐击穿强度和介电可调性先增加后减少。PMMA含量(体积分数)为15%的BST/PVDF?PMMA₁₅复合材料的综合性能最佳:介电常数为23.2,介电损耗为0.07,耐击穿强度为1412 kV·cm^-1,在550 kV·cm^-1偏压场下,介电可调性为26.2%。     

Control of Semiconductor Particle Size in Sol-Gel Thin Films

Thin silica and silica-titania films containing CdS and PbS quantum size particles were obtained by separate preparation of the matrix and the colloidal sols and successive mixing. Sulfide particles were obtained by reaction of metal acetates with thioacetamide and control of particle size was achieved by surface capping agents. Powders and thin films deposited on soda-lime slides were prepared and characterized by XRD. Absorption spectra were recorded on films. The nonlinear refractive index was measured by anm-line technique on a CdS-doped sample. The nonlinear effect was found to be reversible and an ₂ value of −3 10⁻⁹ cm²/kW was measured.     

电沉积三维多孔Pt/SnO2薄膜及其对甲醇的电催化氧化

在高电流密度下以阴极析出的氢气泡为“模板”电沉积三维多孔Sn薄膜, 经在200 ℃ 2 h和400 ℃ 2 h热处理氧化后电沉积金属Pt, 制得三维多孔的Pt/SnO₂ (3D-Pt/SnO₂)薄膜. 通过扫描电镜(SEM)和X射线衍射(XRD)分析了薄膜的形貌和结构. 结果显示Pt主要沉积在SnO₂枝晶上, 形成Pt_shell/SnO_2core结构的枝晶. 在0.5 mol•dm^－3 H₂SO₄＋1.0 mol•dm^－3 CH₃OH溶液中的循环伏安结果表明, 3D-Pt/SnO₂薄膜电极在酸性溶液中电催化氧化甲醇的性能优于电沉积的纯铂电极, 而且具有较高的稳定性.     

总气压与Ar/O2流量比对直流对向靶磁控溅射TiO2薄膜光催化性能的影响

采用对向靶磁控溅射法在不同气压和Ar/O₂流量比条件下, 以氟化SnO₂ (FTO)导电玻璃为基底制备了多晶TiO₂薄膜. 台阶仪测量结果显示所制备TiO₂薄膜的平均厚度约为200 nm. 随着溅射气压的升高, TiO₂薄膜由锐钛矿与金红石混晶结构转变为纯锐钛矿结构. 分别采用场发射扫描电镜(FESEM)和原子力显微镜(AFM)分析了不同气压和Ar/O₂流量比对TiO₂薄膜表面形貌的影响, 结果显示TiO₂薄膜的表面粗糙度随溅射总气压和Ar/O₂流量比的增加而增大. 以初始浓度为100×10^-6 (体积分数)的异丙醇(IPA)气体为目标物检测所制备TiO₂薄膜的光催化性能, 并分析该气相光催化反应的机理, 在紫外照射条件下异丙醇先氧化为丙酮再被氧化为CO₂.当总溅射气压为2.0 Pa、Ar/O₂流量比为1:1时, 溅射所得TiO₂薄膜具备最优光催化活性并可在IPA降解反应中保持较高的催化活性和稳定性.     

Effect of La3+ content on the properties of ferroelectric Bi4?xLaxTi3O12 (BLT) thin films prepared by aqueous chemical solution deposition

Lanthanum substituted bismuth titanate thin films were deposited using an aqueous chemical solution deposition method. Varying the composition of Bi_4−x La _x Ti₃O₁₂, with x = 0.5, 0.65, 0.75 and 0.85, is shown to have a large influence on the microstructure and properties of the films. Increasing the amount of La³⁺, x, from 0.5 to 0.85 led to a decrease of the remanent polarization (P _r) from 6.2 to eventually 0 μC/cm². This decrease of P _r is explained by means of X-ray diffraction (XRD) study, which shows that there is an increased preference for c-axis orientation upon increasing the La³⁺ concentration. Furthermore, a strong decrease of the grain size upon increasing x is observed in a scanning electron microscopic (SEM) study. The concurrent increase of domain pinning on the grain boundaries is a second effect which may be responsible for the deterioration of the ferroelectric property at larger x.