Dislocations in synthetic quartz crystal are mainly propagated from the seed crystals. Therefore, low dislocation seed crystals are fhdamental when growing low dislocation synthetic quartz. A new technique called "fi-ame seed method" was developed to produce low dislocation seed crystal. In previous studies, it was confumed that the technique cutting Z-cut seed from the +X region is effective to decrease dislocations. However, this technique has one problem;the Ydimension becomes shorter than the original seed crystal as the result of the appearance of m-face. This new technique provided low dislocation seed without shortening of the Y-dimension by controlling the appearance of m-face. This technique can remove the other defects such as twins and cracks. Therefore applying this technique to the natural quartz containing twins or cracks, it is expected to remove these defects.
A new fatigue testing method was developed to study the fracture mechanical fatigue properties of brittle hard materials such as high performance ceramics at room and elevated temperatures. Several computer-simulated experiments were first conducted to get the optimum specimen configuration and loading condition. Chevron-notched specimens made of PSZ (Partially Stabilized Zirconia) and glass were used to examine the performance of testing technique including the stability of newly designed eccentric compression loading device and the accuracy of the measuring method based on the extended unloading elastic compliance method. Calibration of crack length was made by using both of the initial equivalent crack length of chevron notch and the final fatigue crack length observed on fracture surface, and it was confirmed that the fatigue crack length detected by using the extended unloading elastic compliance method was quite satisfactory from the view point of accuracy.
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