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Pressure‐induced structural phase transformation in cobalt(II) dicyanamide
Author(s) -
Yakovenko Andrey A.,
Chapman Karena W.,
Halder Gregory J.
Publication year - 2015
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520615005867
Subject(s) - dicyanamide , monoclinic crystal system , materials science , orthorhombic crystal system , compressibility , phase (matter) , bulk modulus , crystallography , cobalt , rutile , thermodynamics , chemistry , crystal structure , composite material , metallurgy , ionic liquid , physics , biochemistry , organic chemistry , catalysis
In situ synchrotron powder diffraction has been used to probe the pressure‐dependent structural properties of the magnetic molecular framework material Co(dca) 2 [dca = dicyanamide or N(CN) 2 − ]. An orthorhombic ( Pmnn ) to monoclinic ( P 2 1 / n ) transformation to a high‐pressure phase, namely γ‐Co(dca) 2 , occurs at 1.1 GPa. Structural determination of γ‐Co(dca) 2 shows that the rutile‐like topology of the pristine material is retained at high pressures, with the lower symmetry allowing a progression of volume‐reducing structural distortions. γ‐Co(dca) 2 was stable at the maximum pressure measured of 4.2 GPa. Both phases were soft, with bulk moduli ( B 0 ) for α‐Co(dca) 2 and γ‐Co(dca) 2 of 13.15 (18) and 9.0 (6) GPa, respectively. Modest uniaxial negative linear compressibility ( K ) of the order of −4 TPa −1 was observed over the entire measured pressure range.