Chien-Chen Diao

Atomic oxygen effect on the in situ growth of stoichiometric YBa2Cu3O7−δ epitaxial films by facing targets 90° off‐axis radiofrequency magnetron sputtering

(110)‐ and (103)‐oriented almost stoichiometric YBa2Cu3O7−δ (YBCO) films have been grown epitaxially on hot SrTiO3 (110) substrates using a 90° off‐axis rf magnetron sputtering technique, for fabrication of vertical sandwich‐type YBCO/insulator/YBCO or YBCO/normal metal/YBCO Josephson junctions utilizing the high‐quality YBCO films. The YBCO epitaxial films with high transition temperatures Tc of ∼90 K have been deposited in situ only under the conditions of substrate temperatures Ts of ∼650–∼700 °C and oxygen partial pressure PO2 of ∼5×10−3–∼10×10−3 Torr, which are in close proximity to the critical stability/decomposition line for YBa2Cu3O6 in the ordinary Y–Ba–Cu–O phase diagram. Using a quadrupole mass spectrometer, a high density of atomic oxygen has directly been observed to be efficiently produced in the sputter glow discharge under the above optimum conditions of PO2. This atomic oxygen has played a key role in promoting the formation of the perovskite structure and the epitaxial growth of the YBC...

Study of Different TiO2 Electrode Structures on Dye-Sensitized Solar Cell

In this research, applications of different TiO2 electrode structures on Dye-Sensitized Solar Cell were investigated. The different TiO2 electrode structures include: (1) synthesis of TiO2 nano-particles and TiO2 film electrode by sol-gel and spin-coating method; (2) fabrication of the TiO2 film electrode by RF Sputtering; (3) fabrication of the rod TiO2 electrode by photo lithography. X-ray diffraction patterns show that the best sintering temperature of nano-TiO2 thin film is 500oC, at which TiO2 anatase phase forms best and the smallest particle-size (8-10 nm) can be obtained. Ultraviolet-visible absorption spectra reveal that the rod TiO2 electrode with TCPP sensitizer adsorbed on has the best optical absorption from 400 nm to 700 nm. The results of current-voltage analyses reveal that the solar cell with rod TiO2 electrode has higher conversion efficiency than the others. This result also provides clear evidence for the contact area between TiO2 electrode and TCPP sensitizer plays an important role on the efficiency of dye-sensitized solar cell.

Preparation of Bi-Layered SrBi2Ta2-xVxO9 Ceramics (0.1 ≦ x ≦ 0.4)

V2O5 is used to substitute Ta2O5 site of the SrBi2Ta2O9 ceramics to form SrBi2Ta2-xVxO9 composition, where 0.1 ≤ x ≤ 0.4. The sintering and the dielectric properties of SrBi2Ta2-xVxO9 ceramics have been developed. For all SrBi2Ta2-xVxO9 composition, the crystal intensities of the (0,0,l) planes increase with the increase of sintering temperature and saturate at 1050C-sintered ceramics, and the increase in the crystal intensities of the (0,0,8) and (0,0,10) planes are more obvious. For the same sintering temperature, the crystal intensities of the (0,0,l) planes increase with the increase of V2O5 content and saturate at SrBi2Ta1.7V0.3O9 ceramics. This study will show that the sintering temperature and V2O5 content have large influences on the maximum dielectric constants (εTc) and the Curie temperatures of SrBi2Ta2-xVxO9 ceramics. Introduction The layer structured bismuth compound ferroelectric has the general formula: An-1Bi2BnO3n+3, where A is usually a divalent ion, such as Sr, Ba, or Pb, and B is Ti, Nb, or Ta [1-3]. Within the bismuth family, SrBi2Ta2O9 ceramics had attracted the most attention in the past years [4-7]. Although the polarization of SrBi2Ta2O9 ceramics is less than the competing Pb(Ti,Zr)O3-based materials, the bismuth-layer compounds are much stable to polarization fatigue free property, i.e. almost no charge loss will happen when polarization is reversed many cycles. In the SrBi2Nb2O9 composition, the substitution of Nb2O5 by V2O5 will lower the sintering temperature and produce materials with enhanced dielectric properties that are useful in many applications [8]. In this study, we are interesting to investigate ceramic materials based on SrBi2Ta2O9 composition, V2O5 is used to substitute for Ta2O5 to form the SrBi2Ta2-xVxO9 compositions. Bulk SrBi2Ta2-xVxO9 materials are sintered at different temperature and their morphologies and crystal phases are examined. The temperature-dependent dielectric characteristics are also investigated as a function of sintering temperature and V2O5 content. Experimental Procedures Reagent-grade raw materials of SrCO3, Bi2O3, Ta2O5, and V2O5 with higher than 99.5% purity were used as starting materials, mixed according to the composition SrBi2Ta2-xVxO9 (x = 0.1, 0.2, 0.3, and 0.4, respectively) and ball-milled for 5h with deionized water. After dried and ground, the powder was calcined at 850C for 3h. After calcination and ground again, then polyvinylalcohol (PVA) was added as a binder. The calcining powder was uniaxially pressed into pellets in a steel die. After debindering, sintering of these pellets was preceded from 900C to 1100C for 4h. The crystal structures of the SrBi2Ta2-xVxO9 ceramics were investigated using XRD patterns, and the morphologies were observed by using scanning electronic micrograph (SEM). The sintered ceramics were painted with Ag-Pd paste and sintered at 700C for 15min. Temperature-dependent dielectric characteristics were measured at 1MHz with an oscillating amplitude (50mV) by an HP4194 impedance analyzer, putting the sintered ceramics in a temperature-programmable testing chamber. Key Engineering Materials Online: 2007-04-15 ISSN: 1662-9795, Vols. 336-338, pp 192-195 doi:10.4028/www.scientific.net/KEM.336-338.192

The Influences of Excess Bi2O3 Content on the Characteristics of 0.8 (Bi0.5K0.5)TiO3-0.2 BaTiO3 Ceramics

The Bi-layer structure bismuth 0.8 Bi0.5K0.5TiO3-0.2 BaTiO3 + x wt% (0.8 BKT-0.2 BT3-x, x = 0, 1, 2, and 3) Bi2O3 ceramic was sintered in air for 2 h from 1000°C to 1100°C. The excess content of Bi2O3 was used as the sintering aid and to compensate the vaporization of Bi2O3 during the sintering process. A narrow range of sintering temperature could be used to densify the 0.8 BKT-0.2 BT3-x ceramics. The addition of excess Bi2O3 would lower down the sintering temperature and extend the temperature range to sinter the 0.8 BKT-0.2 BT3-x ceramics. The Curie temperatures of 0.8 BKT-0.2 BT3-x ceramics would be shifted to lower temperatures as the sintering temperatures and the content of excess Bi2O3 increase.

Electrical Characteristics of Bi4Ti3O12 Ferroelectric Thin Films Annealed under Different Temperature for Applications in Nonvolatile Memory Devices

Ferroelectric Bi4Ti3O12 thin films are deposited on Pt/Ti/Si(100) (MFM structure) and SiO2/Pt/Ti/Si (100) (MFIS) substrates using RF magnetron sputtering at room temperature. The Bi4Ti3O12 thin films are then annealed by a rapid thermal annealing (RTA) process conducted in oxygen atmosphere ranging from 500°C–700°C. X-ray diffraction examination reveals that the crystalline orientation of 700°C-annealed Bi4Ti3O12 thin films is better than that of 500°C-annealed ones. Finally, the top view and cross-sectional images of SEM, memory windows, leakage currents and polarization characteristics of the Bi4Ti3O12 thin films are well developed

Low Temperature Sintering (Ba1-xSrx)TiO3 Ceramics by Using CuO-TiO2 Mixture as Sintering Aid

1wt% CuO-TiO2 (molar ratio, CuO/TiO2= 1) mixture is added as the liquid phase sintering aid to develop the sintering and dielectric characteristics of (Ba1-xSrx)TiO3 (x=0, 0.1, and 0.2) ceramics. The crystal characteristics of calcined (Ba1-xSrx)TiO3 powders and sintered (Ba1-xSrx)TiO3 ceramics are developed by using X-ray diffraction method. The calcined (Ba1-xSrx)TiO3 powders and 1050oC-sintered (Ba1-xSrx)TiO3 ceramics reveal a tetragonal or pseudo-cubic structure and the 1150oC-sintered(Ba1-xSrx)TiO3 ceramics reveal a tetragonal structure. Sintered at 1100oC, the (Ba1-xSrx)TiO3 ceramics present a porous structure; Sintered at 1150oC, the (Ba1-xSrx)TiO3 ceramics present a uniform growth. The grain size decreases with the increase of SrO content. In this study, the dielectric characteristics of CuO-TiO2 mixture-fluxed (Ba1-xSrx)TiO3 ceramics are also developed.

Effects of Substrate and Annealing Temperatures on the Characteristics of SrBi4Ti4O15 Thin Films

In this study, radio frequency (RF) sputtering was used as the method and the layer-structured bismuth compound of SrBi4Ti4O15 + 4 wt% Bi2O3 ferroelectric ceramic was used as the target to deposit the SrBi4Ti4O15 (SBT) thin films. The addition of excess Bi2O3 content in the target ceramic was used to compensate the vaporization of Bi2O3 during the sintering and deposition processes. SBT ferroelectric thin films were deposited on Pt/Ti/SiO2/Si under optimal RF magnetron sputtering parameters with different substrate temperatures for 2 h. After that the SBT thin films were post-heated using rapid temperature annealing (RTA) method. The dielectric and electrical characteristics of the SBT thin films were measured using metal-ferroelectric-metal (MFM) structure. From the physical and electrical measurements of X-ray diffraction pattern, scanning electronic microscope (SEM), I-V curve, and C-V curve, we had found that the substrate temperature and RTA-treated temperature had large influences on the morphology, the crystalline structure, the leakage current density, and the dielectric constant of the SBT thin films.

Structure and resistivity of vacancy‐ordered Sr2Ti2O5 films in high‐Tc superconducting heterostructures

Vacancy‐ordered Sr2Ti2O5 (110) epitaxial films in situ deposited on YBa2CU3O7−δ (YBCO) (103) epitaxial films are studied for insulating layers in high‐Tc superconducting heterostructures. The ordered structure is interpreted by a 2×2×2 superstructure with a long‐range ordered arrangement of oxygen vacancies in the film and a 2×1 surface superstructure with an ordered arrangement of surface oxygen vacancies on it. The resistivity of the Sr2Ti2O5 film sandwiched between Au and YBCO films is measured as a function of the thickness and temperature, and discussed with respect to electron scattering induced by a deficiency of oxygen in the film and at the film boundary.

Investigation of a wheel-knife module with feedback torque signal for generation six to eight flat panel cutting

In this paper, we would investigate a wheel-knife module with feedback torque signal for generation six to eight flat panel cutting. The system of the investigated wheel-knife module was designed by using the servo type because thus type had the following figure merits. (1) The servo type could proceed with the stable cutting motion and its cutting depth would have a uniform value. (2) When the cutting process was carried out, the servo type could have smaller residual chippings. (3) The residual chippings on the cutting lines were more uniform and smaller than other system. The figure merit of the investigated system is that the signal can be feedback to the panel cutting platform, then we can immediately control the model and process of wheel-knife module via the control system of the panel cutting platform.

Investigation of an auto motion and high efficiency platform for generation six to eight flat panel

As the area of glass panel becomes larger and the thickness becomes thinner (from 0.5mm to about 0.3mm), the method for the load of glass panel under the mass-production will be changed to another method, for example by platform with auto load function. In this study, we investigated a platform for generation six (G6, 1850 × 1500 mm) to generation eight (G8, 2460 × 2160 mm). The investigated auto panel-cutting platforms had the human-machine interface which could be designed to have the function of choosing the different cutting area. The investigated platform has two special functions, which can be controlled by the human-machine interface. The first is the diagnosis model, which is used to choose the cutting area for the analysis of the fail problem. The second is the accepted goods and unaccepted goods (OK/NG) model. The area of cutting glass panels could be controlled by the computer-integrated manufacturing (CIM) program.