TITLE

Low-Temperature X-ray Diffraction Studies of the Crystallographic Parameters and Thermal Expansion of (CH[sub 3])[sub 2]NH[sub 2]Al(SO[sub 4])[sub 2] · 6H[sub 2]O Crystals

AUTHOR(S)
Sheleg, A. U.; Zub, E. M.; Semenov, K. N.
PUB. DATE
September 2000
SOURCE
Physics of the Solid State;Sep2000, Vol. 42 Issue 9, p1731
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
The a,b,c, and β crystallographic parameters of the (CH[sub 3])[sub 2]NH[sub 2]Al(SO[sub 4])[sub 2] · 6H[sub 2]O crystal (DMAAS) have been measured by x-ray diffraction in the 90–300-K temperature range. The thermal expansion coefficients along the principal crystallographic axes α[sub a],α[sub b], and α[sub c] have been determined. It was shown that, as the temperature is increased, the parameter α decreases and b increases, whereas c decreases for T < T[sub c] (where T[sub c] is the transition temperature) and increases for T > T[sub c], so that one observes a minimum in the c = f(T) curve in the region of the phase transition (PT) temperature T[sub c]∼152 K. The thermal expansion coefficients α[sub a],α[sub b], and α[sub c] vary in a complicated manner with increasing temperature, more specifically, α[sub a] and α[sub c] assume negative values at low temperatures, and the α[sub a] = f(T),α[sub b] = f(T), and α[sub c] = f(T) curves exhibit anomalies at the PT point. The crystal has been found to be substantially anisotropic in thermal expansion. © 2000 MAIK “Nauka / Interperiodica”.
ACCESSION #
7324091

 

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