Hysteretic behavior of Fe(phen)2(NCS)2 spin-transition microparticles vs. the environment: A huge reversible component resolved by first order reversal curves

ABSTRACTLinearized augmented plane wave (LAPW) results are presented for FeO at high pressures using the Generalized Gradient Approximation (GGA) to study the high-spin low-spin transition previously predicted by LAPW with the Local Density Approximation (LDA) and Linear Muffin Tin Orbital (LMTO-ASA) methods within the GGA. We find a first-order transition at a pressure of about 105 GPa for the cubic lattice, consistent with earlier LAPW results, but much lower than obtained with the LMTO. The results are generally consistent with recent Mössbauer experiments that show a transition at about 100 GPa. We also discuss the origin of the transition, and show that it is not due to electrostatic crystal-field effects, but is rather due to hybridization and band widening with pressure. Examination of experimental data and computations suggest that the high pressure hexagonal phase of FeO is likely a polytype between the B8 NiAs and anti-B8 AsNi structures. The former is predicted to be an antiferromagnetic metal, and the latter an antiferromagnetic insulator. Implications for geophysics are discussed.

Download Full-text

Hysteretic Behaviors of Yield Stress in Smart ER/MR Materials: Experimental Results

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.326-328.1459 ◽

2006 ◽

Vol 326-328 ◽

pp. 1459-1462

Author(s):

Young Min Han ◽

Quoc Hung Nguyen ◽

Seung Bok Choi ◽

Kyung Su Kim

Keyword(s):

Yield Stress ◽

Smart Materials ◽

Hysteretic Behavior ◽

Preisach Model ◽

Hysteresis Model ◽

First Order ◽

Input Field ◽

Nonlinear Hysteresis ◽

Field Dependent ◽

Discrete Manner

This paper experimentally investigates the hysteretic behaviors of yield stress in electrorheological (ER) and magnetorheological (MR) materials which are known as smart materials. As a first step, the PMA-based ER material is prepared by dispersing the chemically synthesized polymethylaniline (PMA) particles into non-conducting oil. For the MR material, commercially available one (Lord MRF-132LD) is chosen for the test. Using the rheometer, the torque resulting from the shear stress of the ER/MR materials is measured, and then the yield stress is calculated from the measured torque. In order to describe the hysteretic behavior of the fielddependent yield stress, a nonlinear hysteresis model of the ER/MR materials is formulated between input (field) and output (yield stress). Subsequently, the Preisach model is identified using experimental first order descending (FOD) curves of yield stress in discrete manner. The effectiveness of the identified hysteresis model is verified in time domain by comparing the predicted field-dependent yield stress with the measured one.

Download Full-text

Evidence of Photo-Thermal Effects on the First-Order Thermo-Induced Spin Transition of [{Fe(NCSe)(py)2}2(m-bpypz)] Spin-Crossover Material

Magnetochemistry ◽

10.3390/magnetochemistry5020021 ◽

2019 ◽

Vol 5 (2) ◽

pp. 21 ◽

Cited By ~ 1

Author(s):

Kamel Boukheddaden ◽

Houcem Fourati ◽

Yogendra Singh ◽

Guillaume Chastanet

Keyword(s):

Thermal Effects ◽

Spin Crossover ◽

Evolution Equations ◽

Thermal Hysteresis ◽

Magnetic Measurements ◽

Equations Of Motion ◽

Spin Transition ◽

Thermal Bath ◽

Trapping Region ◽

First Order

We have investigated by means of optical microscopy and magnetic measurements the first-order thermal spin transition of the [{Fe(NCSe)(py)2}2(m-bpypz)] spin-crossover compound under various shining intensities, far from the light-induced spin-state trapping region. We found evidence of photo-heating effects on the thermally-induced hysteretic response of this spin-crossover material, thus causing the shift of the thermal hysteresis to lower temperature regions. The experimental results are discussed in terms of the apparent crystal temperature and are analyzed theoretically using two evolution equations of motion, written on the high-spin (HS) fraction and heat balance between the crystal and the thermal bath. A very good qualitative agreement was found between experiment and theory in the stationary regime, explaining the experimental observations well and identifying the key factors governing these photo-thermal effects.

Download Full-text

The effect of pressure on the thermal hysteresis of the first‐order spin transition in bis(1,10‐phenanthroline‐2‐carbaldehyde phenylhydrazone) iron (II) complexes

The Journal of Chemical Physics ◽

10.1063/1.449209 ◽

1985 ◽

Vol 83 (6) ◽

pp. 3055-3061 ◽

Cited By ~ 35

Author(s):

E. König ◽

G. Ritter ◽

J. Waigel ◽

H. A. Goodwin

Keyword(s):

Thermal Hysteresis ◽

Spin Transition ◽

Effect Of Pressure ◽

First Order

Download Full-text

Neutron powder diffraction studies of two spin transition FeIIcomplexes under pressure

Journal of Applied Crystallography ◽

10.1107/s0021889808006481 ◽

2008 ◽

Vol 41 (3) ◽

pp. 637-640 ◽

Cited By ~ 24

Author(s):

Vincent Legrand ◽

Frédéric Le Gac ◽

Philippe Guionneau ◽

Jean-François Létard

Keyword(s):

Ambient Temperature ◽

Powder Diffraction ◽

Structural Transition ◽

Spin Crossover ◽

Spin Transition ◽

Neutron Powder Diffraction ◽

Continuous Transition ◽

First Order ◽

New Type ◽

Symmetry Change

The pressure dependences of the lattice parameters of two spin transition compounds have been derived from neutron powder diffraction measurements at ambient temperature. The study of Fe(PM–AzA)2(NCS)2[PM isN-2′-pyridylmethylene and AzA is 4-(phenylazo)aniline] has been used to validate this new type of investigation of spin crossover compounds, and the study of Fe(PM–BiA)2(NCS)2(BiA is 4-aminobiphenyl) has allowed the atypical spin crossover behaviour of this compound under pressure to be explained. In addition, this complex exhibits a pressure-induced structural transition with an associated symmetry change, inducing the transformation of Fe(PM–BiA)2(NCS)2into a different polymorph that avoids a first-order spin transition in favour of continuous transition.

Download Full-text

A first order reversal curve investigation of pressure hysteresis in multiferroics spin transition compound

Journal of Applied Physics ◽

10.1063/1.2831335 ◽

2008 ◽

Vol 103 (7) ◽

pp. 07B905 ◽

Cited By ~ 8

Author(s):

Radu Tanasa ◽

Alexandru Stancu ◽

Epiphane Codjovi ◽

Jorge Linares ◽

François Varret ◽

...

Keyword(s):

Spin Transition ◽

First Order

Download Full-text

Damping Force Control of MR Damper for a Passenger Vehicle Considering Hysteretic Compensator

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.47-50.145 ◽

2008 ◽

Vol 47-50 ◽

pp. 145-148 ◽

Cited By ~ 1

Author(s):

Min Sang Seong ◽

Kum Gil Sung ◽

Seung Bok Choi

Keyword(s):

Force Control ◽

Mr Damper ◽

Hysteretic Behavior ◽

Test Facility ◽

Passenger Vehicle ◽

Damping Force ◽

First Order ◽

Field Dependent ◽

Preisach Hysteresis ◽

Vehicle Test

This paper presents damping force control performances of a magnetorheological (MR) damper via new control strategy considering hysteretic behavior of the field-dependent damping force. In order to achieve this goal, a commercial MR damper which is applicable to passenger vehicle is adopted and its field-dependent damping force is experimentally evaluated. Since the field-dependent damping force shows the hysteretic behavior which significantly affects to control characteristics of the system, Preisach hysteresis model for the MR damper is established and its first order descending (FOD) curves are experimentally identified. Subsequently, a feed-forward compensator strategy for the MR damper is formulated and damping force control is evaluated. In addition, vibration control performances are experimentally evaluated with quarter-vehicle test facility.

Download Full-text

Reversible and Irreversible Processes in Drying and Wetting of Soil

Materials ◽

10.3390/ma13010135 ◽

2019 ◽

Vol 13 (1) ◽

pp. 135

Author(s):

Ilie Bodale ◽

Alexandru Stancu

Keyword(s):

Irreversible Processes ◽

Type Model ◽

Preisach Model ◽

Predictive Capability ◽

Capillary Hysteresis ◽

First Order ◽

System A ◽

Analytical Functions ◽

Forc Diagram ◽

Reversible Component

In this article, we provide a detailed description of a modeling technique for the capillary hysteresis in a soil-like porous material based on a Generalized Preisach Model. The identification of the reversible and irreversible Preisach distributions was performed with the first-order reversal curve (FORC) diagram technique, which is very popular now in magnetism and in other areas of science to give a fingerprint of the studied system. A special attention was given to the evaluation of the reversible component. In this case, we used a set of data published in 1965 by Morrow and Harris which has been used as a reference by many other researchers since. The advantage of this approach is that the experimental FORC distributions can be described with analytical functions and easily implemented in the mentioned Preisach-type model. Our research is also focused on the development of a characterization tool for the soil using the soil-moisture hysteresis. The systematic use of scanning curves provides a (FORC) diagram linked to the physical properties of the studied soil. The agreement between the experimental data and the Preisach model using the set of parameters found through the FORC technique is really noticeable and gives a good practical option to the researchers to use a method with a strong predictive capability.

Download Full-text