0000000000161206

AUTHOR

C.p. Köhler

showing 3 related works from this author

Anomalous pressure dependence of the Lamb-Mössbauer factor in a spin crossover system

1986

The dependence of the f-factor on temperature and on pressure up to 1500 bar has been measured in the spin crossover compound [Fe(2-pic-ND2)3]cl2·EtOD. In the transition region around Tc=146.7 K the pressure dependence of f shows an anomalous increase, which can be explained on the basis of a theoretical model for spin transitions developed by us.

Nuclear and High Energy PhysicsCondensed matter physicsChemistrySpin crossoverLamb–Mössbauer factorPhysical and Theoretical ChemistryPressure dependenceCondensed Matter PhysicsAtomic and Molecular Physics and OpticsSpin-½Bar (unit)Hyperfine Interactions
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Nature of the phase transition in spin crossover compounds

1990

Abstract Starting from the phenomenological free energy describing the spin equilibrium of continuous or gradual high spin (HS) ⇌ low spin (LS) transitions a reduced equation of state has been derived which is of the type known in mean field theories. The continuous HS ⇌ LS transitions of [Fe(2-pic-ND 2 ) 3 ]Cl 2 ·EtOD (2-pic = 2-picolylamine) at ambient pressure and p = 1200 bar and of [Fe(2-pic) 3 ]Cl 2 -MeOH can be classified as isobars above the critical point of the system. Around and below the critical point a complex behaviour is expected for thermodynamic reasons combined with the consequences of an elastic interaction mechanism between the HS and LS complex molecules in the crystal…

Phase transitionChemistryHydrostatic pressureThermodynamicsGeneral ChemistryCondensed Matter PhysicsNuclear magnetic resonanceMean field theoryCritical point (thermodynamics)Spin crossoverIsobarSpin density waveGeneral Materials ScienceSolid solutionJournal of Physics and Chemistry of Solids
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Anomalous pressure dependence of the Lamb-Mössbauerf-factor in the spin crossover system [Fe(2-pic-ND2)3]Cl2·EtOD

1987

The pressure dependence of the Lamb-Mossbauer factor of the spin crossover compound [Fe(2-pic-ND2)3]Cl2·EtOD(2-pic-ND2=2-picolylamine, deuterated at the−NH2 group) has been measured at pressures up to 1500 bar and at three temperatures (115.7, 146.7, 185.6 K) around the transition temperatureT t=135 K. The temperature dependence of the unit cell volume has been determined by X-ray diffraction. In the transition region (T=146.7 K), the pressure dependence of thef-factor shows an anomalous increase as compared to the dependence below and above the transition. The behaviour off(p, T), its anomaly and absolute value, can be consistently explained within a theoretical model which treats the comp…

DiffractionNuclear and High Energy PhysicsCondensed matter physicsChemistryIsotropyAbsolute valueCondensed Matter PhysicsAtomic and Molecular Physics and OpticsPoisson's ratiosymbols.namesakeDeuteriumSpin crossoversymbolsPhysical and Theoretical ChemistryAnomaly (physics)Bar (unit)Hyperfine Interactions
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