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Updated: Sep 18, 2025
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Pressure Dependence of Structural Behavior in the Polymorphs of Fe(PM-BiA)2(NCS)2
Pulkit Prakash1, Hend Shahed1, Ji Qi1
1Jülich Center for Neutron Science-2, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
Abstract:
The pressure dependence of structural behavior in the orthorhombic (Pccn, PI) and monoclinic (P21/c, PII) polymorphs of the compound [Fe(PM-BiA)2(NCS)2], where PM-BiA = (N-(2'-pyridylmethylene)-4-amino-bi-pheynyl), is studied with synchrotron single-crystal X-ray diffraction and vibrational spectroscopy. Both polymorphs are stable up to ∼1.5 GPa, with a spin state transition occurring only in polymorph PII under hydrostatic conditions as documented by single-crystal synchrotron diffraction. The diffraction data also provide evidence of the formation of superstructures for both PI, with a doubled c axis, and PII, with a doubled b axis, on applying pressures above 2 GPa. The LS and HS states seem to coexist at high-pressures for both polymorphs studied with synchrotron infrared spectroscopy at quasi-hydrostatic conditions. Such results indicate that the occurrence of spin-crossover transformations in [Fe(PM-BiA)2(NCS)2] might strongly depend on the stress in the sample.
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