X-Ray Measurement of Order in CuAuII

概要

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Measurement of order in the long period ordered alloy CuAuII has been made on a powdered specimen of the Cu-51.7 at.% Au alloy at temperatures between 375 and 400℃ by the use of an X-ray diffractometer equipped with a high-temperature specimen holder. The Fourier coefficients, S_1 and S_3, of the order parameters defined by Tachiki and Teramoto for this ordered alloy have been determined by comparing the intensities of the superlattice reflections, 1, 1+1/2M, 2, 1, 1-1/2M, 2, 1, 1+3/2M, 0, 1, 1+1/2M, 0, 1, 1-1/2M, 0, 1, 1-3/2M, 0, with the intensity of the fundamental reflection, 0, 0, 2. The observed values of the coefficients are considerably lower than the ideal values for a perfectly ordered state. |S_1| being about 80-70% and |S_3| being only about 40-30% of the ideal ones. The observed lowering of order in CuAuII is in a rough agreement with the theoretical prediction given by the above investigators. |S_1| and |S_3| do not appreciably decrease with rising temperature between 375 and 390℃, but they begin to fall as the temperature approaches T_c. This temperature dependence of order is some what different from the theoretical prediction.
社団法人日本物理学会の論文
1967-01-05