scholarly journals Round robin optical measurements of preferred orientation in nearly isotropic pyrocarbon

1979 ◽  
Author(s):  
D. Stevens
Author(s):  
Lucien F. Trueb

A new type of synthetic industrial diamond formed by an explosive shock process has been recently developed by the Du Pont Company. This material consists of a mixture of two basically different forms, as shown in Figure 1: relatively flat and compact aggregates of acicular crystallites, and single crystals in the form of irregular polyhedra with straight edges.Figure 2 is a high magnification micrograph typical for the fibrous aggregates; it shows that they are composed of bundles of crystallites 0.05-0.3 μ long and 0.02 μ. wide. The selected area diffraction diagram (insert in Figure 2) consists of a weak polycrystalline ring pattern and a strong texture pattern with arc reflections. The latter results from crystals having preferred orientation, which shows that in a given particle most fibrils have a similar orientation.


Author(s):  
R.A. Ploc

The manner in which ZrO2 forms on zirconium at 300°C in air has been discussed in the first reference. In short, monoclinic zirconia nucleates and grows with a preferred orientation relative to the metal substrate. The mode of growth is not well understood since an epitaxial relationship which gives minimum misfit between the zirconium ions in the metal/oxide combination is not realized. The reason may be associated with a thin cubic or tetragonal layer of ZrO2 between the inner oxygen saturated metal and the outer monoclinic zirconia.


Author(s):  
W. E. Lee

An optical waveguide consists of a several-micron wide channel with a slightly different index of refraction than the host substrate; light can be trapped in the channel by total internal reflection.Optical waveguides can be formed from single-crystal LiNbO3 using the proton exhange technique. In this technique, polished specimens are masked with polycrystal1ine chromium in such a way as to leave 3-13 μm wide channels. These are held in benzoic acid at 249°C for 5 minutes allowing protons to exchange for lithium ions within the channels causing an increase in the refractive index of the channel and creating the waveguide. Unfortunately, optical measurements often reveal a loss in waveguiding ability up to several weeks after exchange.


2003 ◽  
Vol 112 ◽  
pp. 365-368 ◽  
Author(s):  
K. K. Jee ◽  
W. Y. Jang ◽  
Y. H. Chung

Author(s):  
Diyan Pertiwi

This study is a class action that aims to improve learning outcomes in subjects PPKn sixth grade students of SDN 002 Ukui Dua. This research is motivated by the low activity and low teacher and student learning outcomes in subjects PPKn. The problem of this study is whether the implementation of a strategy to answer alternately patterned circle round robin can improve student learning outcomes in subjects PPKn in the sixth grade SDN 002 Ukui Dua? This PPKn was conducted over two cycles. Data collection techniques in this research using collection observation techniques, achievement test, and documentation. Techniques of analysis in this study is an analysis of the activities of teachers and students and learning outcomes in subjects PPKn sixth grade students SDN 02 Ukui Dua Kecamatant Ukui. The result showed that the activity of teachers has increased. At the first meeting of the first cycle of 41% was obtained with Simply Perfect category and the second meeting reached 55% with the category Fairly Perfect. In the second cycle 3 meeting to reach 75% by the Perfect category and the 4th meeting of the second cycle reaches 85% with the Perfect category. While the activity of students has increased. At the first meeting of the first cycle reaches 51% with the category Fairly Perfect and the second meeting with the percentage of 66% to the category Perfect. After the second cycle of the third meeting with a percentage of 75% with the Perfect category while in attendance for-4 with the percentage of 94% to the category of Most Perfect. Learning outcomes of students also increased from the previous students who achieve KKM only 8 votes with a percentage (45%) after the first cycle an increase in students worth over KKM which reached 14 people with a percentage of 70%. Cycle II students who achieve KKM 17 (85%).


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