Calorimetric study of chiral liquid crystals with a twist-grain-boundary phase

1995 ◽  
Vol 52 (5) ◽  
pp. 5000-5003 ◽  
Author(s):  
Tom Chan ◽  
Carl W. Garland ◽  
H. T. Nguyen
Keyword(s):  
Liquid Crystals ◽  
Grain Boundary ◽  
Boundary Phase ◽  
Calorimetric Study ◽  
Chiral Liquid Crystals

Chiral random grain boundary phase of achiral hockey-stick liquid crystals

Soft Matter ◽  
2014 ◽  
Vol 10 (45) ◽  
pp. 9105-9109 ◽  
Author(s):  
Dong Chen ◽  
Haitao Wang ◽  
Min Li ◽  
Matthew A. Glaser ◽  
Joseph E. Maclennan ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Grain Boundary ◽  
Boundary Phase ◽  
Hockey Stick

Chiral random grain boundary phase of achiral hockey-stick liquid crystals showing randomly oriented smectic blocks with flat smectic layers.

Twisted Grain Boundary Phase in Binary Mixture of Liquid Crystals

2013 ◽  
Vol 574 (1) ◽  
pp. 1-8 ◽  
Author(s):  
T. N. Govindaiah ◽  
Nagappa ◽  
H. R. Sreepad
Keyword(s):  
Liquid Crystals ◽  
Binary Mixture ◽  
Grain Boundary ◽  
Boundary Phase

Examination of Fracture Interfaces in Silicon Nitride

1975 ◽  
Vol 33 ◽  
pp. 60-61
Author(s):  
Nancy J. Tighe
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Slow Crack Growth ◽  
Ceramic Materials ◽  
Grain Boundary Sliding ◽  
Boundary Phase ◽  
Turbine Engines ◽  
Boundary Sliding

Silicon nitride is one of the ceramic materials being considered for the components in gas turbine engines which will be exposed to temperatures of 1000 to 1400°C. Test specimens from hot-pressed billets exhibit flexural strengths of approximately 50 MN/m2 at 1000°C. However, the strength degrades rapidly to less than 20 MN/m2 at 1400°C. The strength degradition is attributed to subcritical crack growth phenomena evidenced by a stress rate dependence of the flexural strength and the stress intensity factor. This phenomena is termed slow crack growth and is associated with the onset of plastic deformation at the crack tip. Lange attributed the subcritical crack growth tb a glassy silicate grain boundary phase which decreased in viscosity with increased temperature and permitted a form of grain boundary sliding to occur.

Characterization of intergranular cuprous oxide in polycrystalline YBa2Cu3O7-x

1988 ◽  
Vol 46 ◽  
pp. 880-881
Author(s):  
Bradley L. Thiel ◽  
Chan Han R. P. ◽  
Kurosky L. C. Hutter ◽  
I. A. Aksay ◽  
Mehmet Sarikaya
Keyword(s):  
Grain Boundary ◽  
Cuprous Oxide ◽  
Room Temperature ◽  
Boundary Phase ◽  
Spectroscopic Techniques ◽  
Transition Width ◽  
Practical Applications ◽  
Thin Foils ◽  
Superconducting Oxides

The identification of extraneous phases is important in understanding of high Tc superconducting oxides. The spectroscopic techniques commonly used in determining the origin of superconductivity (such as RAMAN, XPS, AES, and EXAFS) are surface-sensitive. Hence a grain boundary phase several nanometers thick could produce irrelevant spectroscopic results and cause erroneous conclusions. The intergranular phases present a major technological consideration for practical applications. In this communication we report the identification of a Cu2O grain boundary phase which forms during the sintering of YBa2Cu3O7-x (1:2:3 compound).Samples are prepared using a mixture of Y2O3. CuO, and BaO2 powders dispersed in ethanol for complete mixing. The pellets pressed at 20,000 psi are heated to 950°C at a rate of 5°C per min, held for 1 hr, and cooled at 1°C per min to room temperature. The samples show a Tc of 91K with a transition width of 2K. In order to prevent damage, a low temperature stage is used in milling to prepare thin foils which are then observed, using a liquid nitrogen holder, in a Philips 430T at 300 kV.

A 2*2 fiber optic switch using chiral liquid crystals

1990 ◽  
Vol 2 (2) ◽  
pp. 147-149 ◽  
Author(s):  
N.K. Shankar ◽  
J.A. Morris ◽  
C.P. Yakymyshyn ◽  
C.R. Pollock
Keyword(s):  
Liquid Crystals ◽  
Fiber Optic ◽  
Chiral Liquid Crystals
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