Fabrication and Microstructure of Grain-Oriented (Bi1/2K1/2)TiO3 Ceramics

2010 ◽  
Vol 445 ◽  
pp. 15-18 ◽  
Author(s):  
Masahiro Saitoh ◽  
Yuji Hiruma ◽  
Hajime Nagata ◽  
Tadashi Takenaka
Keyword(s):  
Grain Growth ◽  
Hot Pressing ◽  
Perovskite Structure ◽  
Single Phase ◽  
Density Ratio ◽  
High Density ◽  
Orientation Factor ◽  
Templated Grain Growth ◽  
High Density Ratio ◽  
High Orientation

Grain-oriented (Bi1/2K1/2)TiO3 (BKT) ceramics were prepared by the reactive templated grain growth (RTGG) method, and a hot-pressing (HP) method was modified on the basis of the RTGG method to obtain dense ceramics. The BKT ceramic sintered at 1060°C showed a single-phase perovskite structure. The grain-oriented BKT prepared by the HP method exhibited a relatively high orientation factor F of 0.82 and a high density ratio of 99%. SEM micrographs of the HP-grain-oriented BKT indicated a textured and poreless microstructure. On the basis of the density ratio of 87% for the grain-oriented BKT without HP, the HP method was considered very effective for improving the density ratio even for the RTGG sample. In addition, the resistivity of the HP-grain-oriented BKT was 1.73 x 1013 •cm.

Piezoelectric Properties and Electric Field-Induced-Strains of Textured (Bi1/2K1/2)TiO3- BaTiO3 Ceramics

2013 ◽  
Vol 566 ◽  
pp. 50-53
Author(s):  
Fumiaki Kawada ◽  
Yuji Hiruma ◽  
Hajime Nagata ◽  
Tadashi Takenaka
Keyword(s):  
Electric Field ◽  
Grain Growth ◽  
Piezoelectric Properties ◽  
Density Ratio ◽  
Orientation Factor ◽  
Templated Grain Growth ◽  
Direction Parallel ◽  
Piezoelectric Strain ◽  
High Orientation ◽  
Piezoelectric Strain Constant

Grain-oriented 0.8(Bi1/2K1/2)TiO3-0.2BaTiO3 (BKT-BT20) ceramics were prepared by the Reactive Templated Grain Growth (RTGG) method. The BKT-BT20 ceramics sintered at 1070°C for 100 h. The grain-oriented BKT-BT20 exhibited relatively high orientation factor, F, of 0.87 and density ratio of 92%. A resistivity of textured BKT-BT20 was 1.29×1013 Ωcm. Piezoelectric strain constant, d33, and the normalized strain, d33*, of the textured BKTBT20 ceramic in the direction parallel (//) to the tape stacking direction were 117 pC/N and 243 pm/V (at 80 kV/cm), respectively.

A Combined Volume of Fluid and Immersed Boundary Method for Modelling of Two-Phase Flows with High Density Ratio

2021 ◽  
Author(s):  
Qiu Jin ◽  
Dominic Hudson ◽  
W.G. Price
Keyword(s):  
Boundary Layer ◽  
Immersed Boundary Method ◽  
Density Ratio ◽  
Volume Of Fluid ◽  
High Density ◽  
Immersed Boundary ◽  
Two Phase Flows ◽  
Two Phase ◽  
Boundary Method ◽  
High Density Ratio

Abstract A combined volume of fluid and immersed boundary method is developed to simulate two-phase flows with high density ratio. The problems of discontinuity of density and momentum flux are known to be challenging in simulations. In order to overcome the numerical instabilities, an extra velocity field is designed to extend velocity of the heavier phase into the lighter phase and to enforce a new boundary condition near the interface, which is similar to non-slip boundary conditions in Fluid-Structure Interaction (FSI) problems. The interface is captured using a Volume of Fluid (VOF) method, and a new boundary layer is built on the lighter phase side by an immersed boundary method. The designed boundary layer helps to reduce the spurious velocity caused by the imbalance of dynamic pressure gradient and density gradient and to prevent tearing of the interface due to the tangential velocity across the interface. The influence of time step, density ratio, and spatial resolution is studied in detail for two set of cases, steady stratified flow and convection of a high-density droplet, where direct comparison is possible to potential flow analysis (i.e. infinite Reynold's number). An initial study for a droplet splashing on a thin liquid film demonstrates applicability of the new solver to real-life applications. Detailed comparisons should be performed in the future for finite Reynold's number cases to fully demonstrate the improvements in accuracy and stability of high-density ratio two-phase flow simulations offered by the new method.

Mineralizing Spinel Formation with Boron-Containing Compounds

2006 ◽  
Vol 45 ◽  
pp. 2254-2259
Author(s):  
Goutam Bhattacharya ◽  
Shao Wei Zhang ◽  
Daniel Doni Jayaseelan ◽  
William Edward Lee
Keyword(s):  
Grain Growth ◽  
Boron Oxide ◽  
Borate Glass ◽  
Single Phase ◽  
Sodium Tetraborate ◽  
Lithium Tetraborate ◽  
Templated Grain Growth ◽  
Spinel Formation ◽  
Phase Spinel ◽  
Spinel Mgal2o4

Spinel (MgAl2O4) formation from stoichiometric MgO and Al2O3 is strongly mineralized by B-containing compounds such as boron oxide (B2O3), lithium tetraborate (Li2B4O7) and sodium tetraborate (Na2B4O7) at 1000°C. TEM confirms that the mineralization with each compound involves borate glass which is presumably formed on cooling from liquid at 1000°C. EDS shows the boron-containing liquids formed from B2O3 and Na2B4O7-mineralized samples contain little alumina suggesting a templated grain growth whereas those in Li2B4O7-mineralized samples dissolve sufficient alumina to suggest dissolution-precipitation is occurring at this temperature. XRD shows that Li2B4O7 is the most effective mineralizer producing single- phase spinel with 3 wt% addition at 1000°C whereas B2O3 produces Mg3B2O6 at 1.5 wt% addition and both B2O3 and Na2B4O7- mineralized samples show incomplete spinelisation which may be explained by the composition of the liquids formed with these two mineralizers.

Laser velocimetry measurements in a high density ratio supersonic shear layer

1997 ◽  
Author(s):  
Jay Hammer ◽  
Roland Anderson ◽  
Rodney Clark ◽  
James Gordon, III ◽  
Jay Hammer ◽  
...  
Keyword(s):  
Shear Layer ◽  
Density Ratio ◽  
High Density ◽  
Laser Velocimetry ◽  
High Density Ratio

Modeling High Density Ratio Incompressible Interfacial Flows

2002 ◽  
Author(s):  
Markus Bussmann ◽  
Douglas B. Kothe ◽  
James M. Sicilian
Keyword(s):  
Mass Flux ◽  
Density Ratio ◽  
Momentum Conservation ◽  
High Density ◽  
Interfacial Flows ◽  
Pressure Gradients ◽  
Careful Evaluation ◽  
Flow Equations ◽  
High Density Ratio ◽  
Consistent Approach

We present an approach to modeling incompressible interfacial flows on fixed meshes that yields solutions at any density ratio. There are two aspects of the methodology that are crucial for obtaining accurate high density ratio solutions: a consistent approach to mass and momentum conservation, by using mass flux information from an interface advection algorithm as the basis for the momentum advection calculation, and a careful evaluation of pressure gradients near the interface. Our particular implementation couples a volume tracking algorithm with a predictor/projection solution of the flow equations on unstructured meshes. We present the methodology, and then the results of several calculations.

Sign in / Sign up

Export Citation Format

Share Document