TY - JOUR

T1 - Ultra-high-angle double-crystal X-ray diffractometry (U-HADOX) for determining a change in the lattice spacing

T2 - Theory

AU - Okazaki, Atsushi

AU - Soejima, Yuji

PY - 2001

Y1 - 2001

N2 - Advantages of high-angle double-crystal X-ray diffractometry (HADOX) have been re-examined. It is found that, by extending the Bragg angle θ up to 89.99°, the accuracy of a change in the lattice spacing to one part in 109-1010 can be attained in proportion to tan θ. In such a case, the dispersion-free condition is so serious that the spacing of the two crystals should be equal within one part in 106. Therefore, this method is appropriate for determining the thermal expansion coefficient in a limited temperature range. To cover a wide temperature range, the temperature of the reference crystal must be adjusted according to the temperature of the specimen crystal; the lattice spacing as a function of temperature can be determined by integrating the temperature derivative of the spacing.

AB - Advantages of high-angle double-crystal X-ray diffractometry (HADOX) have been re-examined. It is found that, by extending the Bragg angle θ up to 89.99°, the accuracy of a change in the lattice spacing to one part in 109-1010 can be attained in proportion to tan θ. In such a case, the dispersion-free condition is so serious that the spacing of the two crystals should be equal within one part in 106. Therefore, this method is appropriate for determining the thermal expansion coefficient in a limited temperature range. To cover a wide temperature range, the temperature of the reference crystal must be adjusted according to the temperature of the specimen crystal; the lattice spacing as a function of temperature can be determined by integrating the temperature derivative of the spacing.

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U2 - 10.1107/S0108767301014064

DO - 10.1107/S0108767301014064

M3 - Article

C2 - 11679702

AN - SCOPUS:0034758625

SN - 0108-7673

VL - 57

SP - 708

EP - 712

JO - Acta Crystallographica Section A: Foundations and Advances

JF - Acta Crystallographica Section A: Foundations and Advances

IS - 6

ER -