Search results for "SSB"

X-ray powder diffraction and LIESST-effect of the spin transition material [Fe(bpp)2](NCS)2·2H2O

2006

Abstract We have studied the X-ray powder diffraction of the spin transition material [Fe(bpp)2](NCS)2 · 2H2O (bpp: 2,6-bis(pyrazol-3-yl)pyridine) at room temperature. Two crystallographic phases have been observed depending on the sample history of this material. The results obtained corroborate the earlier observations from magnetic and calorimetric studies. Relatively prolonged exposure of the sample to X-rays caused a structural change. LIESST and Reverse-LIESST effects, characterised by 57Fe Mossbauer spectroscopy, have been observed in this material.

Post-sintering heat treatment effect on the coercivity of sintered (Nd,Dy)15(Fe,Co,Mo,Al)77B8 permanent magnets

2000

Abstract The effect of heat treatment on the intrinsic coercivity, iHc and microstructure were investigated for sintered (Nd,Dy)15(Fe,Co,Mo,Al)77 B8 permanent magnet. The microstructure has been investigated by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray spectroscopy and Mossbauer spectroscopy. The observed behaviour of iHc may be caused by a superposition of the following effects: (i) the distribution of the nonmagnetic phases and the ratio of the amount of hard magnetic Nd2Fe14B-phase to the amount of the residual phases; (ii) homogeneous distribution of elements in the main phases; (iii) removing the stresses in the phases; and (iv) diffusion of Al, …

Active Translucent Envelopes in Warm and Hot Areas – An innovative multifunctional, dry-assembled components for BIPV

2014

International directives that regulates buildings energy efficiency and environmental sustainability establish strict parameters for the construction of a new generation of “Zero Energy Buildings” indicating transmittance limits for building envelope components and encouraging the use of renewable sources. In this sense, the PV sector aims at the definition of novel efficient solutions for the integration in the building envelope, standing out for their multifunctional features. After an overview on the main PV technologies and building integrated applications, focusing on semi-transparent envelope solutions, the paper shows the results of a research carried out at the Department of Archite…

Delocalized Nature of theEδ′Center in Amorphous Silicon Dioxide

2005

We report an experimental study by electron paramagnetic resonance (EPR) of E(')(delta) point defect induced by gamma-ray irradiation in amorphous SiO2. We obtained an estimation of the intensity of the 10 mT doublet characterizing the EPR spectrum of such a defect arising from hyperfine interaction of the unpaired electron with a 29Si (I=1/2) nucleus. Moreover, determining the intensity ratio between this hyperfine doublet and the main resonance line of E(')(delta) center, we pointed out that the unpaired electron wave function of this center is actually delocalized over four nearly equivalent silicon atoms.

Lattice Instability and Competing Spin Structures in the Double Perovskite InsulatorSr2FeOsO6

2013

The semiconductor Sr2FeOsO6, depending on temperature, adopts two types of spin structures that differ in the spin sequence of ferrimagnetic iron-osmium layers along the tetragonal c axis. Neutron powder diffraction experiments, 57Fe Mossbauer spectra, and density functional theory calculations suggest that this behavior arises because a lattice instability resulting in alternating iron-osmium distances fine-tunes the balance of competing exchange interactions. Thus, Sr2FeOsO6 is an example of a double perovskite, in which the electronic phases are controlled by the interplay of spin, orbital, and lattice degrees of freedom.

LIESST Effect in Fe(II) 1,2,4-Triazole Chains

2016

One-dimensional Fe(II) chains with 1,2,4-triazole as bridging ligands present the LIESST effect; i.e. their spin state switched from low-spin to high-spin after light irradiation at low temperature. This account summarizes the findings in this area of photomagnetism where 57Fe Mossbauer spectroscopy was used as a primary detection tool of the LIESST effect.

57Fe- MÖSSBAUER EMISSION SPECTROSCOPY OF AN IRON (II) COMPLEX WITH TEMPERATURE DEPENDENT SPIN STATE

1980

ANOMALOUS SPIN STATES OF IRON (II) IN MÖSSBAUER EMISSION SPECTRA OF [57 Co(2-CH3-phen),] (ClO4)2.2 H2O AND [57Co(2-CH3O-phen)3] (ClO4)2.H2O

1976

Anomalous Spin Transition Observed in Bis(2,6-bis(pyrazol-3-yl)pyridine)iron(II) Thiocyanate Dihydrate

2003

Bis(2,6-bis(pyrazol-3-yl)pyridine)iron(II) thiocyanate dihydrate undergoes a two-step singlet (1A1) ⇄ quintet (5T2) transition in which both steps are associated with thermal hysteresis. Thermal cycling of the sample results in its conversion to a second phase which displays a single-step transition with a very narrow hysteresis loop. This second phase slowly reverts to the initial phase on standing at 300 K. The interconversions are completely reversible. The spin state changes have been monitored by measurement of magnetism and Mossbauer spectra and by differential scanning calorimetry (DSC) studies.

Iron Mineralogy of Venus' Surface Investigated by M�ssbauer Spectroscopy

2000

Abstract We discuss the use of Mossbauer (MB) spectroscopy to study Fe-bearing minerals on Venus' surface. At present, there is no direct information about the mineralogy of Venus' surface, although in situ chemical analyses by X-ray fluorescence (XRF) spectroscopy have been done by the Venera 13, 14, and Vega 2 spacecraft at three landing sites. The XRF elemental analyses are sensitive to major rock-forming elements heavier than sodium and show the presence of several mass percent iron. Normative mineralogical calculations model the Fe mineralogy at the Venera 13, 14, and Vega 2 landing sites, but the actual Fe minerals present are unknown. We calculate synthetic MB spectra for the normati…