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Low-Temperature Transitions of Some Ammonium Salts

Published online by Cambridge University Press:  06 March 2019

M. Stammler ,
D. Orcutt  and
P. C. Colodny
M. Stammler
Affiliation:
Aerojet-General Corporation Sacramento, California
D. Orcutt
Affiliation:
Aerojet-General Corporation Sacramento, California
P. C. Colodny
Affiliation:
Aerojet-General Corporation Sacramento, California
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Abstract

X-ray diffraction studies were performed on ammonium fluoroborate [NH4BF4], ammonium perchlorate [NH4ClO4], ammonium chloride [NH4CI] and ammonium phosphate [(NH4)H2PO4] within a temperature range of ambient to −190°C. For these experiments a specimen holder was designed to effect rapid cooling of the sample. Results indicate that the fluorob orate and perchlorate salts undergo a polymorphic transition at −190°C. The decreasing intensities of the (011) and (112) reflections of the orthorhombic modification indicates a firstorder reaction. No transition was observed when these salts were cooled to −40°C. The ammonium chloride shows a transition at about −30°C which confirms the results obtained by G. H. Goldschmidt and D. G. Hurst. The ammonium phosphate (NH4)H2PO4, which is tetragonal at ambient temperature also undergoes a transition if cooled to −190°C. The kinetics of this reaction are discussed.

Type
Research Article
Information
Advances in X-Ray Analysis , Volume 6: Eleventh Annual Conference on Applications of X-ray Analysis, August 8-10, 1962 , 1962 , pp. 202 - 209
Copyright
Copyright © International Centre for Diffraction Data 1962

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