ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
All the nine elastic constants of orthorhombic ammonium fluoroberyllate [(NH4)2.BeF4] have been determined at room temperature (305 K) from the measurement of the intensities of thermal diffuse scattering of X-rays using a single-crystal diffractometer. Monochromatic Mo Kα radiation obtained by reflection from a curved quartz crystal was used. The intensity of diffusely scattered X-rays has been corrected for divergence, polarization, skew correction, absorption, second-order thermal diffuse scattering and general scattering. Isodiffusion contours have been drawn around the 400 node. The values of elastic constants in units of 1010 Nm-2 are C11 = 3.82 (30), C22 = 3.56 (28), C33 = 2.45 (19), C44 = 0.96 (05), C55 = 1.01 (05), C66 = 0.79 (04), C12 = 1.78 (18), C13 = 1.52 (15), C23 = 1.41 (14). An estimate of the Debye temperature has been made by calculating the mean sound velocity in the crystal from these elastic-constant values.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0567739480001842
