Thin films of spin-crossover coordination polymers with large thermal hysteresis loops prepared by nanoparticle spin coating

2014 ◽  
Vol 50 (70) ◽  
pp. 10074-10077 ◽  
Author(s):  
Daisuke Tanaka ◽  
Naoki Aketa ◽  
Hirofumi Tanaka ◽  
Takashi Tamaki ◽  
Tomoko Inose ◽  
...  
Keyword(s):  
Thin Films ◽  
Coordination Polymers ◽  
Spin Coating ◽  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Hysteresis Loops ◽  
Spin Transitions

Spin-crossover nanoparticles form homogeneous thin films on substrates, which show abrupt spin transitions with large thermal hysteresis loops.

scholarly journals Iron(II) Spin Crossover Complexes with 4,4′-Dipyridylethyne—Crystal Structures and Spin Crossover with Hysteresis

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 581 ◽  
Author(s):  
Katja Dankhoff ◽  
Charles Lochenie ◽  
Birgit Weber
Keyword(s):  
Coordination Polymers ◽  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Hysteresis Loops ◽  
Structure Property ◽  
Crossover Behavior ◽  
Structure Property Relationship ◽  
Wide Hysteresis ◽  
Xrd Patterns ◽  
Relationship Of

Three new iron(II) 1D coordination polymers with cooperative spin crossover behavior showing thermal hysteresis loops were synthesized using N2O2 Schiff base-like equatorial ligands and 4,4′-dipyridylethyne as a bridging, rigid axial linker. One of those iron(II) 1D coordination polymers showed a 73 K wide hysteresis below room temperature, which, upon solvent loss, decreased to a still remarkable 30 K wide hysteresis. Single crystal X-ray structures of two iron(II) coordination polymers and T-dependent powder XRD patterns are discussed to obtain insight into the structure property relationship of those materials.

Compensation effects and relation between the activation energy of spin transition and the hysteresis loop width for an iron(ii) complex

2016 ◽  
Vol 18 (25) ◽  
pp. 16690-16699 ◽  
Author(s):  
Mark B. Bushuev ◽  
Denis P. Pishchur ◽  
Elena B. Nikolaenkova ◽  
Viktor P. Krivopalov
Keyword(s):  
Hysteresis Loop ◽  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Activation Barrier ◽  
Spin Transition ◽  
Hysteresis Loops ◽  
High Activation ◽  
Activation Barriers ◽  
Spin Crossover Complexes ◽  
Hysteresis Loop Width

Wide thermal hysteresis loops for iron(ii) spin crossover complexes are associated with high activation barriers: the higher the activation barrier, the wider the hysteresis loop for a series of related spin crossover systems.

scholarly journals Elastic Origin of the Unsymmetrical Thermal Hysteresis in Spin Crossover Materials: Evidence of Symmetry Breaking

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 828
Author(s):  
Mamadou Ndiaye ◽  
Nour El Islam Belmouri ◽  
Jorge Linares ◽  
Kamel Boukheddaden
Keyword(s):  
Symmetry Breaking ◽  
High Spin ◽  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Spin Transition ◽  
Hysteresis Loops ◽  
Point Of View ◽  
Self Organization ◽  
Spin States ◽  
Heating And Cooling

The jungle of experimental behaviors of spin-crossover materials contains a tremendous number of unexpected behaviors, among which, the unsymmetrical hysteresis loops having different shapes on heating and cooling, that we often encounter in literature. Excluding an extra effect of crystallographic phase transitions, we study here these phenomena from the point of view of elastic modeling and we demonstrate that a simple model accounting for the bond lengths misfits between the high-spin and low-spin states is sufficient to describe the situation of unsymmetrical hysteresis showing plateaus at the transition only on cooling or on heating branches. The idea behind this effect relates to the existence of a discriminant elastic frustration in the lattice, which expresses only along the high-spin to low-spin transition or in the opposite side. The obtained two-step transitions showed characteristics of self-organization of the spin states under the form of stripes, which we explain as an emergence process of antagonist directional elastic interactions inside the lattice. The analysis of the spin state transformation inside the plateau on cooling in terms of two sublattices demonstrated that the elastic-driven self-organization of the spin states is accompanied with a symmetry breaking.

scholarly journals Design of Bistable Gold@Spin-Crossover Core-Shell Nanoparticles Showing Large Electrical Responses for the Spin Switching

2019 ◽  
Author(s):  
Ramón Torres-Cavanillas ◽  
Rocher Sanchis-Gual ◽  
Julien Dugay ◽  
Marc Coronado-Puchau ◽  
Dr. Mónica Giménez Marqués ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Spin Transition ◽  
Hysteresis Loops ◽  
Large Change ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Simple Protocol ◽  
Order Of Magnitude ◽  
Core Shell Nanoparticles

<p>A simple protocol to prepare core-shell gold@spin-crossover (Au@SCO) nanoparticles (NPs) based on the 1D spin-crossover [Fe(Htrz)<sub>2</sub>(trz)](BF<sub>4</sub>) coordination polymer is reported. The synthesis relies on a two-step approach consisting on a partial surface ligand substitution of the citrate-stabilized Au NPs followed by the controlled growth of a very thin layer of the SCO polymer. As a result, colloidally stable core@shell spherical NPs of 19 nm in size exhibiting a narrow distribution in sizes have been obtained, revealing a switchable SCOshell of <i>ca.</i>4 nm. Temperature-dependent charge transport measurements of an electrical device based on assemblies of these Au@SCO NPs display well-defined, reproducible and sharp thermal hysteresis loops in the conductance near room temperature. This device is characterized both, by a large change in conductance upon spin state switching, and a remarkable transition abruptness, as compared with other memory devices based on the pristine SCO NPs. As a result, the sensitivity of the device to the spin transition is dramatically improved, with values for the ON/OFF ratio which are an order of magnitude better than the best ones obtained in previous SCO devices.</p>

scholarly journals BaTiO3–CoFe2O4–BaTiO3 trilayer composite thin films prepared bychemical solution deposition

2020 ◽  
Author(s):  
Roberto Köferstein
Keyword(s):  
Thin Films ◽  
Acetic Acid ◽  
Phase Formation ◽  
Formation Process ◽  
Spin Coating ◽  
Hysteresis Loops ◽  
Solution Deposition ◽  
Two Samples ◽  
Ir And Raman ◽  
Phase Formation Process

Multiferroic BaTiO3–CoFe2O4–BaTiO3 thin films were synthesized by spin coating of Co(NO3)2–Fe(NO3)3 and Ba(OAc)2–Ti(i-OPr)4 dissolved in a mixture of acetic acid and dimethylformamide. Stepwise thermaltreatment at 200, 400 and 800◦C led to the desired phases. The phase formation process was monitoredby thermoanalytic, XRD, IR and Raman measurements. SEM was used to characterize the structure and thickness of each layer. Two samples with different thicknesses of perovskite and spinel layers are discussed. Sample 1 consists of 120 nm CoFe2O4 between two 70 nm BaTiO3 layers. For sample 2, the 90 nm BaTiO3 top and bottom layers are enclosing 220 nm CoFe2O4. The surface qualities were determined byAFM indicating rms roughness values of about 4 nm. Magnetic investigations reveal slightly anisotropicbehavior. Polarization measurements show hysteresis loops (Ps(max)= 29 µC cm−2; Ps(max)= 17 mC cm−2) with switching peaks at the corresponding coercive fields.

scholarly journals Design of Bistable Gold@Spin-Crossover Core-Shell Nanoparticles Showing Large Electrical Responses for the Spin Switching

2019 ◽  
Author(s):  
Ramón Torres-Cavanillas ◽  
Rocher Sanchis-Gual ◽  
Julien Dugay ◽  
Marc Coronado-Puchau ◽  
Dr. Mónica Giménez Marqués ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Spin Transition ◽  
Hysteresis Loops ◽  
Large Change ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Simple Protocol ◽  
Order Of Magnitude ◽  
Core Shell Nanoparticles

<p>A simple protocol to prepare core-shell gold@spin-crossover (Au@SCO) nanoparticles (NPs) based on the 1D spin-crossover [Fe(Htrz)<sub>2</sub>(trz)](BF<sub>4</sub>) coordination polymer is reported. The synthesis relies on a two-step approach consisting on a partial surface ligand substitution of the citrate-stabilized Au NPs followed by the controlled growth of a very thin layer of the SCO polymer. As a result, colloidally stable core@shell spherical NPs of 19 nm in size exhibiting a narrow distribution in sizes have been obtained, revealing a switchable SCOshell of <i>ca.</i>4 nm. Temperature-dependent charge transport measurements of an electrical device based on assemblies of these Au@SCO NPs display well-defined, reproducible and sharp thermal hysteresis loops in the conductance near room temperature. This device is characterized both, by a large change in conductance upon spin state switching, and a remarkable transition abruptness, as compared with other memory devices based on the pristine SCO NPs. As a result, the sensitivity of the device to the spin transition is dramatically improved, with values for the ON/OFF ratio which are an order of magnitude better than the best ones obtained in previous SCO devices.</p>

scholarly journals Iron(II) Spin Crossover Polymers of Planar N2O2 Schiff Base Templates and 4,4’-bis(pyridyl)urea Bridges

2019 ◽  
Vol 6 (1) ◽  
pp. 10-18 ◽  
Author(s):  
Lisa Zappe ◽  
Charles Lochenie ◽  
Thomas Martin ◽  
Birgit Weber
Keyword(s):  
Schiff Base ◽  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Crystal Packing ◽  
Magnetic Measurements ◽  
Hysteresis Loops ◽  
Complete Removal ◽  
Axial Ligand ◽  
Trinuclear Complex ◽  
Crossover Behavior

Introduction:The synthesis of four new iron(II) coordination polymers [Fe(L1a)(bpua)] (1), [Fe(L1b)(bpua)](0.5bpua) (2), [Fe(L2a)(bpua)] (3), [Fe(L1b)(bpua)](yEtOH) (5) and one trinuclear complex [{Fe(L1a)(bpua)(MeOH)}2-µ{Fe(L1a)}](xMeOH) (4) with Schiff base-like N2O2coordinating equatorial ligands (L1a, L1b and L2a) and 4,4’-bis(pyridyl)urea (bpua) as bridging axial ligand is described.Materials and Methods:Single crystal X-ray structure elucidation of the trinuclear module4and of the coordination polymer5reveals the presence of HS-LS-HS chains and all-HS infinite 1-D strands, respectively. As anticipated the presence of the bridging urea supports the supramolecular concatenation within an extended hydrogen-bonding network. Magnetic measurements reveal spin crossover behavior for four of the five complexes (1–4) that is strongly solvent dependent.Results and Conclusion:Interestingly, in two cases, complete removal of the solvent from the crystal packing leads to wider thermal hysteresis loops.

Thermal hysteresis loops in spin-crossover compounds analyzed in terms of classical Preisach model

1998 ◽  
Vol 34 (4) ◽  
pp. 2213-2219 ◽  
Author(s):  
H. Constant-Machado ◽  
A. Stancu ◽  
J. Linares ◽  
F. Varret
Keyword(s):  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Hysteresis Loops ◽  
Preisach Model

Iron(ii) spin crossover complexes with diaminonaphthalene-based Schiff base-like ligands: 1D coordination polymers

2016 ◽  
Vol 40 (5) ◽  
pp. 4687-4695 ◽  
Author(s):  
Charles Lochenie ◽  
Andreas Gebauer ◽  
Ottokar Klimm ◽  
Florian Puchtler ◽  
Birgit Weber
Keyword(s):  
Schiff Base ◽  
Structural Properties ◽  
Coordination Polymers ◽  
Spin Crossover ◽  
Hysteresis Loops ◽  
Bridging Ligands ◽  
Wide Hysteresis ◽  
Spin Crossover Complexes

Iron(ii) spin crossover coordination polymers with diaminonaphthalene derived Schiff base-like ligands were synthesised, and their magnetic and structural properties were analysed. Rigid bridging ligands having up to 40 K wide hysteresis loops were observed.

Spin-crossover in an iron(iii) complex showing a broad thermal hysteresis

2021 ◽  
Author(s):  
Cyril Rajnák ◽  
Romana Mičová ◽  
Ján Moncoľ ◽  
Ľubor Dlháň ◽  
Christoph Krüger ◽  
...  
Keyword(s):  
Schiff Base ◽  
Schiff Base Ligand ◽  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Mononuclear Complex ◽  
Hysteresis Width ◽  
Thermally Induced

A pentadentate Schiff-base ligand 3,5Cl-L2− and NCSe− form a iron(iii) mononuclear complex [Fe(3,5Cl-L)(NCSe)], which shows a thermally induced spin crossover with a broad hysteresis width of 24 K between 123 K (warming) and 99 K (cooling).

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