STRESS CONTROLLED FERROELECTRIC (BA0.5Sr0.5)TiO3 THIN FILMS PREPARED ON GD2O3/SRTiO3(001) BY A PULSED LASER DEPOSITION

ABSTRACT

Stress controlled epitaxial ferroelectric Ba_0.5Sr_0.5TiO₃ (BST) films have been deposited on Gd₂O₃/SrTiO₃ by pulsed laser deposition with oxygen background pressure of 200 mTorr at the deposition temperature of 750°C. In order to control the stress in BST films, oxygen pressures for Gd₂O₃ buffer layers have been varied from 0.1 to 100 mTorr, while that of BST films have been fixed at 200 mTorr. It has been found that the lattice parameters of the BST films deposited on Gd₂O₃ were changed. Furthermore, microwave properties of co-planar waveguide (CPW) fabricated on BST films were investigated by a HP 8510C vector network analyzer from 1–20 GHz. Large dielectric tunabilities were observed from the CPW's fabricated on BST films deposited on Gd₂O₃ layers deposited at low and high oxygen pressures, 0.1 and 100 mTorr, respectively.     

Hybrid functional IrO_2-TiO_2 thin film resistor prepared by atomic layer deposition for thermal inkjet printheads

IrO2-TiO2 thin films were prepared by atomic layer deposition using Ir(EtCp)(COD) and titanium isopropoxide (TTIP). The resistivity of IrO2-TiO2 thin films can be easily controlled from 1 500 to 356.7 μΩ·cm by the IrO2 intermixing ratio from 0.55 to 0.78 in the IrO2-TiO2 thin films. The low temperature coefficient of resistance(TCR) values can be obtained by adopting IrO2-TiO2 composite thin films. Moreover, the change in the resistivity of IrO2-TiO2 thin films was below 10% even after O2 annealing process at 600 °C. The step stress test results show that IrO2-TiO2 films have better characteristics than conventional TaN0.8 heater resistor. Therefore, IrO2-TiO2 composite thin films can be used as a heater resistor material in thermal inkjet printhead.     

Solar Collector Testing in the European Community

The work of the CEC Collector Testing Group is discussed, and it is concluded that the participating laboratories, which have been working together since 1976, are contributing significantly to the development of solar collectors in Europe.

Test methods for flat plate liquid heating collectors are presented, together with the results from five Round Robin test programmes. Causes of scatter in test results are analysed and pyranometer calibration procedures are shown to have improved as a result of collaborative work between the CEC and the International Energy Agency (IEA).

Work on collector durability and reliability is gathering momentum, and will soon lead to the publication of collector design guidelines. Recommendations for methods of measuring the optical properties of collector materials are also in draft

Future work will see a change of emphasis, away from flat plate liquid heating collector testing and towards the development of test methods for air heating collectors and for domestic hot water heating systems.     

ILC for non-minimum phase system

In this paper we propose a design method of an iterative learning controller (ILC) for a non-minimum phase (NMP) system by model-matching theory. The ILC consists of two learning filters acting on both the previous input signal and the previous error signal. To design the learning filters, we convert the convergence condition of the ILC into the model-matching problem and get the stable and proper learning filter by solving the Nevanlinna's algorithm. To show the usefulness of the proposed algorithm, some design examples are included.     

液压挤压对复合铸造Al3003/Al4004包覆材料显微组织的影响(英文)

研究液压对混合复合铸造Al 3003/Al 4004包覆材料微观组织变化的影响。复合铸造Al 3003/Al 4004包覆材料试样为圆形,由Al 3003(外部)和Al 4004(内部)材料组成。采用液压设备,在温度423 K、挤压比5的条件下制造试样。在挤压之前,Al 4004材料的直径为80 mm,Al 3003材料的厚度为35 mm,在挤压后,2种材料的直径和厚度分别为30 mm和5 mm。研究了2个试样的微观组织和硬度。在挤压之前,复合铸造Al 3003/Al 4004包覆材料横截面的硬度以抛物线的形式向中心增大。然而,在挤压后,Al 4004材料的硬度几乎没有变化。在挤压之前,Al 3003和Al 4004材料的界面存在大量直径超过1 mm的大空洞,这些大空洞随着液压过程的进行而消失。     

Curved crack propagation in homogeneous and graded materials

Deflection and deviation of cracks commonly occurs because of asymmetry in crack‐tip stresses in both homogeneous materials and functionally graded materials (FGMs); yet the analysis of curved cracks has been limited to simple crack shapes, otherwise the analysis would involve extensive levels of computation. The present study investigates the approximation of curved cracks with simplified shapes. A simple analytical model justifying the use of crack‐shape approximations, developed in an earlier study on stationary curved cracks in homogeneous materials, is outlined. Then, the approach is applied to propagating cracks in both homogeneous and graded material structures. Results are presented from finite element (FE) simulations of crack propagation using exact and simplified crack shapes. The use of an approximated crack shape can provide basic estimates for crack propagation path and critical load. However, systematic divergence can occur between predictions for exact and approximated crack shapes, particularly in inhomogeneous material configurations, and so the development of solutions for non‐straight cracks in FGMs would be expedient.     

Evaluation of Lactic Acid Bacteria for Extending the Shelf Life of Shrimp

Forty-four strains of lactic acid bacteria (LAB) were tested for inhibitory activity against three strains of Pseudomonas, Vibrio parahaemolyticus and naturally occurring microflora on fresh deheaded shrimp. Cell-free filtrates and cell suspensions of six strains of LAB were inhibitory to growth of Pseudomonas on agar lawns. Degree of inhibition depended upon medium used for cultivation of LAB prior to testing and the presence or absence of LAB cells on the test lawns. Filtrates were generally more inhibitory than cell suspensions. Certain strains of Streptococcus lactis and Lactobacillus casei inhibited rate of growth of Pseudomonas in broth culture. Neither LAB retarded development of microflora of iced shrimp stored at 5 and 12°C. L. casei may have had an inhibitory effect on rate of growth of V. parahaemolyticus on iced shrimp. Overall, data indicate that treatment of fresh shrimp with LAB to extend shelf life during storage on ice may not be practical.     

Development of XY scanner with minimized coupling motions for high-speed atomic force microscope

The design and fabrication processes of a novel scanner withminimized coupling motions for a high-speed atomic force microscope (AFM) were addressed.An appropriate design modification was proposed through the analyses of the dynamic characteristics of existing linear motion stages using a dynamic analysis program,Recurdyn.Because the scanning speed of each direction may differ,the linear motion stage for a high-speed scanner was designed to have different resonance frequencies for the modes,with one dominan...