A5050780604- Magnetic and transport properties of perovskites and related materials
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Solid-state spectroscopy and crystallography
- Advanced Condensed Matter Physics
- Magnetism in coordination complexes
- Magnetic Properties of Alloys
- Rare-earth and actinide compounds
- Inorganic Fluorides and Related Compounds
- Shape Memory Alloy Transformations
- Thermal Expansion and Ionic Conductivity
- Crystallography and molecular interactions
- Organic and Molecular Conductors Research
- Multiferroics and related materials
- Hydrogen Storage and Materials
- Lanthanide and Transition Metal Complexes
- Advanced Thermodynamics and Statistical Mechanics
- Physics of Superconductivity and Magnetism
- Advanced Thermoelectric Materials and Devices
- High-pressure geophysics and materials
- Inorganic Chemistry and Materials
- Advanced Chemical Physics Studies
- Perovskite Materials and Applications
- Chemical Thermodynamics and Molecular Structure
- Metal-Organic Frameworks: Synthesis and Applications
Instituto de Nanociencia y Materiales de Aragón
2011-2025
Universidad de Zaragoza
2015-2025
Centro Médico Sanitas Zaragoza
2017
Consejo Superior de Investigaciones Científicas
2003-2015
Unidades Centrales Científico-Técnicas
2015
Universitat de València
2008
Centre National de la Recherche Scientifique
1996-1997
Laboratoire de Cristallographie et Sciences des Matériaux
1997
The three-dimensional metal–organic framework Gd(HCOO)3 is characterized by a relatively compact crystal lattice of weakly interacting Gd3+ spin centers interconnected via lightweight formate ligands, overall providing remarkably large magnetic:non-magnetic elemental weight ratio. resulting magnetocaloric effect per unit volume decidedly superior in than the best known magnetic refrigerant materials for liquid-helium temperatures and low-moderate applied fields. Recent years have witnessed...
Molecoolers: An unprecedentedly large cryogenic magnetocaloric effect is observed in gadolinium acetate tetrahydrate (see picture, Gd pink, O red, C gray). The change its magnetic entropy ascribed to the high density combined with dominant ferromagnetism. For first time a molecular complex, direct measurements of corroborate indirect estimates based on heat capacity and magnetization. Detailed facts importance specialist readers are published as "Supporting Information". Such documents...
We present a study of the giant magnetocaloric effect in MnAs produced by magnetostructural first-order phase transition. Results deduced from magnetization, M, and heat capacity, Cp,B(T), are compared discussed. Some spurious effects explained, especially spike isothermal entropy change, ΔST, occurring at TC when obtained via Maxwell relation (∂S/∂B)T=(∂M/∂T)B. Alternative determination methods given to circumvent this problem. The is explained as an artifact due incorrect application path...
Abstract Geometric spin frustration in low-dimensional materials, such as the two-dimensional kagome or triangular antiferromagnetic nets, can significantly enhance change of magnetic entropy and adiabatic temperature following a applied field, that is, magnetocaloric effect. In principle, an equivalent outcome should also be observable certain high-symmetry zero-dimensional, molecular, structures with frustrated topologies. Here we report experimental realization this heptametallic...
Low-temperature neutron diffraction and field-dependent heat capacity measurements for the monazite GdPO${}_{4}$ compound shows some very interesting properties. In particular it displays a large magnetocaloric effect promise in applications cooling at low temperatures.
Magnetocaloric properties of a ${\text{Ni}}_{50}{\text{Mn}}_{36}{\text{Co}}_{1}{\text{Sn}}_{13}$ ferromagnetic shape memory alloy have been studied experimentally in the vicinity first-order magnetostructural phase-transition low-temperature paramagnetic $\text{martensite}\ensuremath{\leftrightarrow}\text{high-temperature}$ austenite. The magnetic entropy change $\ensuremath{\Delta}{S}_{m}$ calculated from magnetization $M(T)$ data measured upon cooling is higher than that estimated heating....
Layered double hydroxides containing paramagnetic NiII and diamagnetic/paramagnetic AlIII/FeIII ions have been prepared characterized. Ni2Al(OH)6(NO3)·nH2O (1), Ni2Fe(OH)6(NO3)·nH2O (2), Ni2Fe(OH)6(C6H8O4)0.5·nH2O (3), Ni2Fe(OH)6(C10H16O4)0.5·nH2O (4) were by coprecipitation at controlled pH as polycrystalline materials with the typical brucite-like structure, alternating layers of hydroxide corresponding anions, which determine interlayer separation. Magnetic studies show appearance...
The ferromagnetic zircon-type phase of ${\mathrm{GdCrO}}_{4}$ presents high values for the magnetocaloric (MC) parameters. This compound has large isothermal entropy changes $\mathrm{\ensuremath{\Delta}}{S}_{T}$ under magnetic field action in a wide temperature range, from 5 to 35 K, reaching maximum $|\mathrm{\ensuremath{\Delta}}{S}_{T}|=29.0\ifmmode\pm\else\textpm\fi{}0.1\phantom{\rule{0.28em}{0ex}}\mathrm{J}/\mathrm{kg}\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ at 22 increment...
We report the magnetic properties and structure of zircon-type compound ${\mathrm{GdVO}}_{4}$, together with isostructural ${\mathrm{NdVO}}_{4}$. At $T\ensuremath{\simeq}2.5$ K, ${\mathrm{GdVO}}_{4}$ undergoes a phase transition to antiferromagnetic ${G}_{z}$, driven mainly by exchange interactions, while anisotropy dipolar interactions are minor contributions. Near liquid-helium boiling temperature, magnetocaloric effect is nearly as large that structurally closely related...
We report the synthesis and structure of a molecular {Gd7} cage formula (iPr2NH2)6[Gd7(μ3-OH)3(CO3)6(O2C t Bu)12] which has crystallographic C3h symmetry. Low temperature specific heat adiabatic demagnetization experiments (the latter achieving temperatures below 100 mK), lead to observation effects both intramolecular dipolar interactions geometric spin frustration. The interaction leads massive rearrangement energy levels such that entropy 2 K are strongly modified while magnetic...
The temperature variation of the (100) and (010) neutron diffraction peak intensities, related only to Nd magnetic moments, have been measured on a ${\mathrm{NdFeO}}_{3}$ single crystal, at temperatures down 70 mK. becomes noticeable below 25 K while gives an appreciable contribution 1 K. Above ${\mathrm{T}}_{\mathrm{N}2}$\ensuremath{\approx}1 intensity is accounted for by electronic moments polarized Nd-Fe exchange field. Near ${\mathrm{T}}_{\mathrm{N}2}$ change slope observed in dependence...
The two-dimensional (2D) polymeric spin crossover (SCO) compound Fe(py)2[Ag(CN)2]2 has been synthesized. shows a two-step transition detected by magnetic, heat capacity, and X-ray diffraction measurements. magnetic moment high-temperature step (step 1) occurring at 146.3 K without hysteresis, while the low-temperature 2) happens 84 on cooling 98.2 heating. These measurements reveal large amount of residual high (HS) species (23%) that HS state trapping occurs rates around 1 min(-1) or...
Molekühlung: Ein ungewöhnlich großer kryogener magnetokalorischer Effekt wird in Gadoliniumacetat-tetrahydrat beobachtet (siehe Bild, Gd rosa, O rot, C grau). Die Änderung der magnetischen Entropie hohen Dichte Verbindung mit einem vorherrschenden Ferromagnetismus zugeschrieben. Zum ersten Mal bei molekularen Komplex bestätigen direkte Messungen des magnetokalorischen Effekts indirekte Schätzungen aus Wärmekapazitäts- und Magnetisierungsdaten.
Perovskite oxides ABO3 continue to be a major focus in materials science. Of particular interest is the interplay between A and B cations as exemplified by intersite charge transfer (ICT), which causes novel phenomena including negative thermal expansion metal-insulator transition. However, ICT properties were achieved optimized cationic substitution or ordering. Here we demonstrate an anionic approach induce using oxyhydride perovskite, EuVO2H, has alternating layers of EuH VO2. bulk EuVO2H...
Attaining sub-Kelvin temperatures remains technologically challenging and often relies on the scarce resource 3He, unless employing adiabatic demagnetization refrigeration. Herein, active coolant typically consists of weakly coupled paramagnetic ions, whose magnetic interaction strengths are comparable in energy to relevant temperature regime cooling. Such interactions depend strongly inter-ion distances, fundamentally hindering realization dense coolants for We present a magnetically...
Abstract In the series of polymeric spin‐crossover compounds Fe(X‐py) 2 [Ag(CN) )] (py=pyridine, X=H, 3‐Cl, 3‐methyl, 4‐methyl, 3,4‐dimethyl), magnetic and calorimetric measurements have revealed that conversion from high‐spin (HS) to low‐spin (LS) state occurs by two‐step transitions for three out five members family (X=H, X=3,4‐dimethyl). The two other (X=3‐Cl 3‐methyl) show respectively an incomplete spin transition no at all, latter remaining in HS whole temperature range. behaviour...
A family of [MIII2MII3]<sup>n+</sup> trigonal bipyramidal cages are characterised in the solution and solid state.
Doping with some metals (Fe, Cu, Ga, Mn, Al) reduces or removes the strong thermal hysteresis in giant magnetocaloric alloys Gd5(SixGe1−x)4. We present heat capacity and direct measurements of isothermal entropy change, ΔST, adiabatic temperature increment, ΔTS, Gd5Si2Ge1.9Ga0.1. TC = 293.6 ± 0.2 K is quite higher than non-substituted similar to values Si rich compounds (i.e. x > 0.5). The results indicate that even this small addition Ga makes transition second-order type, as a usual...
Magnetization, heat capacity and direct measurements of the magnetocaloric effect show that EuGd2O4 EuDy2O4 have a remarkably large at cryogenic temperatures, owing to their high magnetic density low ordering temperatures. The Gd derivative orders antiferromagnetically TN = 4.6 K, while its largely exceeds reference refrigerant Gadolinium Gallium Garnet (GGG) above 5 K. Dy undergoes two phase transitions TC1 3.65 K TC2 4.7 respectively, which are result peculiar arrangement: first sublattice...
${(\mathrm{MnNiSi})}_{0.56}{(\mathrm{FeNiGe})}_{0.44}$ belongs to a new family of alloys, similar MnAs, showing magnetostructural first-order transition near room temperature with large latent heat and magnetocaloric effect (MCE). From isothermal magnetization, remarkable values the entropy change have been reported, such as $|\mathrm{\ensuremath{\Delta}}{S}_{T}|=11.5$ J/kg K at 290 for small field 1 T, or $|\mathrm{\ensuremath{\Delta}}{S}_{T}|=70.1$ 5 T on slightly different composition....
Direct determinations of the isothermal entropy increment, \(-\Delta S_T\), in Heusler alloy Ni\(_{50}\)CoMn\(_{36}\)Sn\(_{13}\) on demagnetization gave positive values, corresponding to a normal magnetocaloric effect. These values contradict results derived from heat-capacity measurements and also previous obtained magnetization measurements, which indicated an inverse effect, but showing different depending technique employed. The puzzle is solved, apparent incompatibilities are...