Orthorhombic Unit Cell Research Articles

Structural and Dielectric Properties of Bi-=SUB=-3-=/SUB=-Ti-=SUB=-1.5-=/SUB=-W-=SUB=-0.5-=/SUB=-O-=SUB=-9-=/SUB=-

Layered perovskite-like oxide Bi3Ti1.5W0.5O9 has been synthesized by the method of high-temperature solid-state reaction. The X-ray diffraction study showed that the compound is single-phase and has the structure of the family of Aurivillius phases (AP) with parameters close to the orthorhombic unit cell corresponding to the space group A21am. The temperature dependences of the relative permittivity ε/ε0 and the loss tangent tgsigma are measured at different frequencies. For the synthesized compound, the piezoelectric modulus d33 was measured. The microstructure of Bi3Ti1.5W0.5O9 has been obtained. Keywords: Aurivillius phases, Bi3Ti1.5W0.5O9, activation energy Ea, Curie temperature TC, piezoelectric modulus d33.

The Crystal Structure of Bornite Cu5FeS4: Ordered Fe and Split Cu

The crystal structure of bornite with ideal formula Cu5FeS4 from the Saishitang skarn copper deposit in Qinghai Province, along with bornite from the Yushui spouting hydrothermal copper deposit in Guangdong Province and the Bofang sandstone copper deposit in Hunan Province, has been refined by single-crystal X-ray diffraction with R1 = 0.0259–0.0483 (I > 2σ) and 0.0338–0.1067 for 2732 to 3273 unique reflections. As represented by the Saishitang sample, it is orthorhombic with a Pbca space group and unit cell parameters a = 10.97016(18) Å, b = 21.8803(4) Å, c = 10.9637(2) Å, V = 2631.61(8) Å3 and Z = 16. The structure is composed of sulfur layers parallel to the (0 1 0) lattice plane with interstices occupied by metal atoms. The Fe atoms occupy two tetrahedral sites with full occupancy, but the Cu atoms are all partially distributed over 20 paired sites, split from 10 sites with a distance ranging from 0.24 Å to 0.54 Å. The Fe-S tetrahedra are not split with Fe-S lengths from 2.2609 Å to 2.3286 Å (average 2.2997 Å). The Cu-S lengths in pyramidal triangles are from 2.218 Å to 2.397 Å (average 2.288 Å), whereas the Cu-S tetrahedra are strongly distorted, with great variations in Cu-S lengths from 2.224 Å to 2.604 Å (average 2.391 Å). The orthorhombic unit cell is stacked from 16 1a-type (5.5 Å) cubes; each cube has one tetrahedrally-coordinated Fe atom, five split from 3- to 4-coordinated Cu atoms, and two vacancies, i.e., 5CuIII–IV+FeIV+2[]+4S. The phenomenon of site-splitting of Cu atoms may provide for a more accurate structure of bornite, allowing for a better understanding of its magnetic properties and ore-formation conditions.

Crystal structures and phase transition of tetrafluoroethylene-vinyl alcohol alternating copolymer

Crystal structure and thermally-induced phase transition have been studied for a novel fluorine polymer or tetrafluoroethylene-vinyl alcohol (TFE-VA) alternating copolymer on the basis of the X-ray diffraction and infrared spectroscopic data analyses. The copolymer exhibits the three kinds of crystalline modification depending on the crystallization conditions. The crystal modification β is obtained by casting from the organic solution at room temperature. The molecular chains are slightly contracted from the zigzag conformation and are packed in the orthorhombic unit cell (a = 9.48 Å, b = 5.38 Å and c (chain axis) = 9.84 Å) with the space group symmetry of P21cn. The heating of the β form above 170 °C causes the irreversible transition to the high-temperature α form (αHT). The thus-created αΗΤ phase cannot change back to the β form anymore. The cooling from the melt induces the crystallization to the αHT phase at first, which transforms to the low-temperature α phase (αLT) apparently continuously and reversibly below 135 °C. The αLT form consists of the statistically disordered packing of the almost fully-extended chains in the unit cell of a = 9.58 Å, b = 5.48 Å and c (chain axis) = 5.01 Å. The αHT takes the similar crystal structure to that of the αLT, but the zigzag chains are packed in the slightly larger unit cell of a = 10.01 Å, b = 5.64 Å and c (chain axis) = 5.02 Å (at 170 °C) in more highly disordered state with thermally-activated motion of the chains. In these crystalline phases, the hydrogen bonds of F⋯H-O and O⋯H-O types are formed to stabilize the chain packing structures.

Investigations of the influence of non-metal dopants on the electronic and photocatalytic properties of ZrTiO4 by density functional theory calculations

In this work, the electronic and photocatalytic properties of non-metal-doped ZrTiO4 are computed using the DFT + U method. This method allows for calculations of the systems with strong correlation electronic effects like several metal oxides, which the standard DFT fails to give the correct predictions. Applying on-site Coulomb energy (U) correction to bulk pristine ZrTiO4 yields an orthorhombic unit cell lattice parameter a = 4.804 Å, b = 5.509 Å, and c = 5.041 Å, which is in good agreement with the experiment. The calculated band gap energy (Eg) for pristine ZrTiO4 with DFT + U is 3.60 eV, which is in excellent agreement with the experimental value of 3.65 eV. Substitutional doping is more likely to occur at the O site than at the Zr or Ti site in the X-doped ZrTiO4 model. F substitution at O atom and Si substitution at Ti or Zr atom are thermodynamically favorable with negative formation energy. Substitutional doping of S at the O site, Se at the Ti site, or S/Se at the Zr site in ZrTiO4 can enhance the photooxidation and photoreduction ability. These materials are expected to have good catalytic activity for water decomposition, CO2 reduction, and N2 fixation in the visible light region.

A general model for the crystal structure of orthorhombic martensite in Ti alloys

The present work develops a novel unified approach to describe the crystal structure of orthorhombic martensite (α′′) in Ti alloys independent of chemical composition. By employing a straightforward yet highly instructive solid sphere model for the basic tetrahedral structural unit the crystal structures involved in the β ↔ α′′/α′ martensitic transformation are categorized into several intermediate configurations. Importantly, a new metric is introduced, δ, which unambiguously characterizes the atomic positions inside the orthorhombic unit cell depending on unit-cell geometry. Furthermore, the exclusive use of relative quantities to describe unit-cell geometry and atom positions renders the approach developed herein independent of alloy content. In this way, shortcomings of commonly suggested structural metrics for α′′ are eliminated. Subsequently, the novel methodology is applied to analyse and compare the crystal structure of α′′ across a broad range of Ti alloys based on experimentally measured unit-cell parameters. From this analysis it emerges that a large fraction of structural configurations along the b.c.c.–Cmcm–h.c.p. transformation path is not observed in quenched alloys. The threshold between the not-observed and the remaining well observed configurations is identified with an ideal Cmcm crystal structure, relative to which the experimentally found α′′ is compressed along its c axis.

Structural and morphological characterization of the crystallites from semicrystalline regions of poly (9,9′-dihexylfluorene)

The aim of this research was to analyze the crystallites of poly(9,9’-dihexylfluorene) (PHF). The pristine polymer was synthesized through the Suzuki cross-coupling polycondensation and the reprecipitation method. Through XRD measurements it was possible to determine the semicrystalline diffraction pattern of the polymer which after the structural adjustment by Le Bail method showed orthorhombic unit cells and crystallites with average sizes of 43.86 Å. Scanning electron microscopy (SEM), revealed spherical nanoparticles morphology with average diameters equal to 69.20 nm. The possible relationship between the fluorescent properties and the parallel alignment of the chains in the crystallites was determined through the absorption spectra in UV-Vis and photoluminescence.

Anomalous magnetoresistance and magneto-thermal properties of the half-Heuslers, RPdSi (R = Y, Gd–Er)

Here, we present a detailed study on the magnetic, magneto-transport, and magneto-thermal properties of the equiatomic half-Heusler compounds with the general formula, RPdSi (R = Y and rare-earth, Gd–Er). These materials crystallize in two different superstructures of the TiNiSi-type orthorhombic unit cell with the space groups Pnma and Pmmn. Our magnetic and heat capacity measurements reveal the onset of an antiferromagnetic (AFM) ordering in the temperature range 3–16 K for all the local moments bearing RPdSi compounds, while the non-magnetic analog, YPdSi exhibits a Pauli-paramagnetic behaviour. The AFM state of these compounds can be tuned by magnetic field and temperature as demonstrated by the magnetic measurements below the Neel temperature (T N). Most importantly, this tuning of the magnetic structure is well documented in the complex temperature and field dependence of magnetoresistance (MR) and magnetocaloric effect (MCE). Our study establishes a striking correlation of the commensurate/incommensurate AFM structure with that of positive/negative MR and MCE in this series of compounds. We emphasize that such a framework applies to a large number of AFM intermetallic systems.

In-plane anisotropic electronic properties in layered α′-In2Se3

In2Se3 polymorphs have been extensively studied because of their diverse physical properties such as piezoelectricity, photoelectricity, and ferroelectricity, thereby showing plentiful promising applications in integrated electronic devices. These diverse properties are strongly dependent on or affected by their atomic bonding arrangement in the crystal phases. Combining lattice symmetry and local atomic perturbation, we demonstrate a novel layered α′-In2Se3 phase by using the first-principles calculations, which is reconstructed from the inverted tetrahedral bonding configuration by the in-plane displacive middle layer Se atom. The optimized structure of monolayer α′-In2Se3 has triple degenerated atomic configurations with different Se atom orientations. We noted that these degenerated atomic configurations exhibit a moderate switching barrier (about 61 meV/f.u.) between them. To further explore this atom-oriented anisotropic property in α′-In2Se3, the electronic properties were studied with an orthorhombic unit cell. The comparative results for the orthogonal Se atom orientations suggest that the nonbonding orbital coupling of the displacive Se atoms induces large in-plane anisotropic optical absorption and electrical transport properties. This study of the layered α′-In2Se3 phase can extend the realm of switchable anisotropic optoelectronic applications in future electronic devices.

Quantification of Cr in Lu1-xSrxFe0.5Cr0.5O3 (0 ≤ x ≤ 1) samples containing impurities using X-ray techniques in combination with several data treatment methodologies

Wet chemical method was applied with the intention of obtaining Lu1-xSrxFe0.5Cr0.5O3 (0 ≤ x ≤ 1) perovskites in polycrystalline form. A systematic study of the crystal structure of the main perovskite phase obtained as well as a characterization of impurities was performed by X-ray techniques: powder diffraction (PXRD), high resolution emission spectroscopy (HR-XES), and photoelectron spectrometry (XPS). The PXRD data of Lu1-xSrxFe0.5Cr0.5O3 (0 ≤ x ≤ 1) were refined using Pbnm orthorhombic unit cell for the perovskite structure. Only samples with x = 0 and x = 0.1 resulted pure; as the amount of Sr increases, it is segregated as impurities, first as SrCrO4 and then as SrFe12O19. The mean oxidation state of Cr in the analyzed samples was obtained from HR-XES by quantifying spectral changes in the Cr-Kβ" and Cr-Kβ2,5 regions by different methodologies: statistical parameters and multivariate methods. The results were compared with the ones obtained by PXRD and XPS. With the last technique Cr6+ ionic concentrations were obtained through the spectral analysis in the region Cr2p3/2–580eV. Similar Cr6+ ionic compositions were obtained using the three X-ray techniques.

An orthorhombic superhard carbon allotrope: Pmma C24

First-principles calculations are used to establish a novel carbon phase with a purely sp3 bonded network and an orthorhombic unit cell of 24 atoms, called Pmma C24. Density functional theory is used to investigate the structural characteristics, elastic properties, and mechanical and electronic properties of this novel carbon structure at different pressures. The mechanical and dynamic stability of Pmma C24 under zero and high pressures is determined by the elastic parameters and phonon spectrum. Interestingly, compared to diamond, this novel carbon phase is less compressible along the c-axis and has a lower relative enthalpy (0.562 ​eV/atom) with a hardness of 63.5 ​GPa. Pmma C24 has higher bulk (347 ​GPa) and shear (246 ​GPa) moduli than C96, tP40 carbon, C72, T-carbon and oP72 carbon. The calculated ratio of the bulk and shear moduli shows that Pmma C24 exhibits brittle characteristics at 0 ​GPa and transforms to a ductile phase under compression forces above 30 ​GPa. Electronic band structure calculations suggest that the proposed novel carbon structure has an indirect band gap of 4.30 ​eV and an indirect and wide semiconductor character.

Structural and stability analysis of Na4Mn4Ti5O18 for energy storage application

We report a single-phase Na4Mn4Ti5O18 oxide prepared via ceramic processing route. Rietveld refinement of X-ray diffraction results indicated orthorhombic unit cell indexed with Pbam space group. Further, structural analysis using X-ray diffraction, transmission electron microscopy and Raman spectroscopy suggested crystal structure comprising two distinct tunnel pathway, polygonal and Z-shaped tunnels with void dimensions ~ 4.07 A and ~ 3.01 A, respectively, suitable for reversible cation transport desirable for energy storage applications. X-ray photoelectron spectroscopy confirmed presence of Mn2+, Mn3+, Mn4+ and Ti4+ in Na4Mn4Ti5O18. Surface morphology in field emission scanning electron microscopy exhibited inhomogenously distributed micro-bead grains separated by well-defined boundaries in good agreement with complex impedance spectrum results. Estimated dc conductivity and surface area is ~ 1.745 × 10− 6 S cm− 1 and ~ 0.66 m2g− 1 respectively. Electrochemical energy storage performance with cell; Na || 1 M NaFSI (EC : DMC, 1:1 v/v%) || Na4Mn4Ti5O18 in voltage range 2.0–3.8 V indicated reversible redox action. Identical cell in voltage range 0.01–2.5 V, exhibited pseudo-capacitive behaviour. Results suggest energy storage possibility with Na4Mn4Ti5O18 electrode.

Observation of novel charge ordering and spin reorientation in perovskite oxide PbFeO3

PbMO3 (M = 3d transition metals) family shows systematic variations in charge distribution and intriguing physical properties due to its delicate energy balance between Pb 6s and transition metal 3d orbitals. However, the detailed structure and physical properties of PbFeO3 remain unclear. Herein, we reveal that PbFeO3 crystallizes into an unusual 2ap × 6ap × 2ap orthorhombic perovskite super unit cell with space group Cmcm. The distinctive crystal construction and valence distribution of Pb2+0.5Pb4+0.5FeO3 lead to a long range charge ordering of the -A-B-B- type of the layers with two different oxidation states of Pb (Pb2+ and Pb4+) in them. A weak ferromagnetic transition with canted antiferromagnetic spins along the a-axis is found to occur at 600 K. In addition, decreasing the temperature causes a spin reorientation transition towards a collinear antiferromagnetic structure with spin moments along the b-axis near 418 K. Our theoretical investigations reveal that the peculiar charge ordering of Pb generates two Fe3+ magnetic sublattices with competing anisotropic energies, giving rise to the spin reorientation at such a high critical temperature.

Synthesis, Polymorphism and Thermal Decomposition Process of (n-C4H9)4NRE(BH4)4 for RE = Ho, Tm and Yb.

In total, three novel organic derivatives of lanthanide borohydrides, n-But4NRE(BH4)4 (TBAREB), RE = Ho, Tm, Yb, have been prepared utilizing mechanochemical synthesis and purified via solvent extraction. Studies by single crystal and powder X-ray diffraction (SC-XRD and PXRD) revealed that they crystalize in two polymorphic forms, α- and β-TBAREB, adopting monoclinic (P21/c) and orthorhombic (Pnna) unit cells, previously found in TBAYB and TBAScB, respectively. Thermal decomposition of these compounds has been investigated using thermogravimetric analysis and differential scanning calorimetry (TGA/DSC) measurements, along with the analysis of the gaseous products with mass spectrometry (MS) and with analysis of the solid decomposition products with PXRD. TBAHoB and TBAYbB melt around 75 °C, which renders them new ionic liquids with relatively low melting points among borohydrides.

Crystal and molecular structure of V-amylose complexed with ibuprofen

Rectangular V-amylose single crystals were prepared by adding racemic ibuprofen to hot dilute aqueous solutions of native and enzymatically-synthesized amylose. The lamellar thickness increased with increasing degree of polymerization of amylose and reached a plateau at about 7 nm, consistent with a chain-folding mechanism. The CP/MAS NMR spectrum as well as base-plane electron and powder X-ray diffraction patterns recorded from hydrated specimens were similar to those of V-amylose complexed with propan-2-ol. Amylose was crystallized in an orthorhombic unit cell with parameters a = 2.824 ± 0.001 nm, b = 2.966 ± 0.001 nm, and c = 0.800 ± 0.001 nm. A molecular model was proposed based on structural analogies with the Vpropan-2-ol complex and on assumptions on the stoichiometry of ibuprofen. The unit cell would contain four antiparallel 7-fold amylose single helices with ibuprofen molecules distributed inside and between the helices.

Elucidating possible crystallographic origins of wake-up mechanisms in ferroelectric hafnia

The wake-up in doped hafnia ferroelectric devices is an extremely important process to understand in order to integrate these materials successfully into working ferroelectric memory devices. The crystallographic origins of this process are clarified with three main mechanisms. Strain relaxation in the ferroelectric orthorhombic phase led to an adjustment of the unit cell volume toward a “bulk-like” value. The undistorted cell allowed for easier polarizability within the unit cell, allowing higher polarization. Reversible phase transformations between the tetragonal and orthorhombic phases depend on the nature of the strain. Finally, a model is developed describing grain reorientation, inducing a 90° rotation of the orthorhombic unit cell and allowing the phase to respond to the E-field more readily under cycling.

On the CN-K coordination modes in Kn[M6-n(CN)6]·xH2O: first evidence of CN-K electron-deficient bonding.

Based on the determination of single crystal XRD structures of potassium hexacyanidometallates and on IR, and Raman data, here we propose for the first time the occurrence of an electron-deficient bonding between the N end of the CN- ligand and the K+ metal center. The crystal structures of Kn[M6-n(CN)6]·xH2O (M = Fe(ii), Ru(ii), Os(ii), Co(iii), Rh(iii), Ir(iii), Pt(iv)) reveal the presence of four types of CN-K interactions: (i) a linear CN-K bond, (ii) the N ends in a bipodal coordination involving two K atoms, (iii) the N ends in a tripodal coordination mode involving three K atoms and (iv) the N ends and the K atoms with the largest K-N distances within the subseries that can be attributed to the electrostatic interactions. The bi- and tripodal coordination modes between the N end of the CN- ligand and K+ ions are atypical and their nature is discussed in this contribution. The CN- ligand N end can behave as a two-electron donor that participates in a three-center two-electron bonding (i.e. Class II μ-L 3c-2e) for a N-bipodal coordination mode or as a two-electron donor that participates in a four-center two-electron bonding (4c-2e) for an N-tripodal coordination mode. Such a possibility is closely related to the π-back donation ability of the CN- ligand, which results in a charge density accumulation on the N end, which could be partially donated to the K atom through an σ-mechanism. For the divalent metals (Fe, Ru, Os), the solids crystallize with a monoclinic unit cell in the C2/c space group, while for the trivalent ones (Co, Rh, Ir), the crystal structure corresponds to an orthorhombic unit cell in the Pbcn space group. Potassium hexacyanidoplatinate(iv) crystallizes with a trigonal unit cell, in the P3[combining macron]1m space group, where each N end is always found coordinating two K atoms. The finding of these novel coordination modes of the CN- ligands, relying on an electron-deficient bonding behavior, paves the way for the design of functional materials based on hexacyanidometallates. The experimental results and the proposed electron-deficient bonding model herein discussed were appropriately supported by the computational calculations.

Self-Assembled Synthesis and Characterization of Novel [Co(1-vinylimidazole)6].NO3 Polymer: Highly Efficient Antimicrobial Agent

Cobalt coordination polymer i.e. [Co(1-VI)6]and#183;NO3 was successfully synthesized with cobalt metal and (VI = vinylimidazole) and characterized by elemental analysis, FTIR, UV/Vis spectroscopy and X-ray crystallography. The structure of the compound was determined by single X-ray crystallography at temperature 296 K with a Bruker APEX II CCD diffractometer using Mo-Kα radiations (λ = 0.71073 and#197;), R = 0.0642 and 0.0989. Orthorhombic unit cell parameters are a = 16.1341 (6) and#197;, b = 16.5179(16) and#197;, c = 18.2664(16) and#197;, V= 4868.0 (8) and#197;, Dx = 4, Mr = 937.91. The X-ray crystallography studies showed that the compound is polymeric in nature, in which cobalt atom coordinated with six N atoms of the 1-vinylimidazole ligands in a distorted orthorhombic geometry. As-prepared compound was screened in vitro against a variety of microorganisms, such as Gram-positive (G +ve) Staphylococcusaureus (S. aureus) and Gram-negative (G -ve) Escherichia coli (E. coli) bacterial strains, and fungal species with Aspergillus niger (A. niger) and Rhizopus stolonifer(R.stolonifer)by applying disk diffusion method. MIC (minimum inhibitory concentration) value for prepared [Co(1-VI)6]and#183;NO3 compound is 125 μg.mL-1a this MIC value cobalt polymer showed higher activity against E. coli and S. aureus () as compared to fungi including; R. StoloniferandA. Niger at 125 μg.mL-1).This study helps to reduce the risk of infectious diseases caused by various microorganisms.

Even–Odd Effect in Aliphatic Polycarbonates with Different Chain Lengths: from Poly (Hexamethylene Carbonate) to Poly (Dodecamethylene Carbonate)

We have characterized a series of aliphatic polycarbonates synthesized by organocatalysis containing a variable number of methylene groups (nCH₂) in their repeating units ranging from nCH₂ = 6 to 12. The melting and crystallization behavior, and crystalline structures were studied by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), and wide-angle X-ray scattering (WAXS). We found a clear even–odd effect in terms of thermal properties and crystalline structure, for nCH₂ = 6 to 9, and a saturation of the even–odd effect, for nCH₂ = 10 to 12. These results were independent of the crystallization conditions employed: nonisothermal, isothermal, and successive self-nucleation and annealing. The even–odd region showed that the even samples had higher melting temperatures than the odd ones and a monoclinic unit cell. On the other hand, the odd samples showed an orthorhombic unit cell. Both even and odd samples exhibited a trans-conformation, with a dilution of the impact of the carbonyl group as evidenced by the weakening of the crystalline memory effect as nCH₂ increases, independent of the even or odd nature of the samples. In the saturation region, methylene, instead of the carbonyl groups, dominated the behavior, resulting in thermal properties that changed almost linearly with nCH₂. The unit cells were all orthorhombic, and the strength of the memory effect was similar, as nCH₂ increased. Accordingly, the samples showed a shift of the FT-IR bands toward a PE-like dominated conformation.

Reinspection of formation of BiFe1-xMnxO3 solid solutions via low temperature sol-gel synthesis route

In this study, BiFe1-xMnxO3 (BiFeMnO; x from 0 to 0.5) solid solutions were prepared by low temperature sol-gel processing. It was demonstrated that structural, magnetic and morphological properties of BiFeMnO samples are dependent on the chemical composition of the synthesized BiFe1-xMnxO3 solid solutions. The thermal behaviour of the Bi–Fe–Mn–O precursor gels was investigated by thermogravimetric and differential scanning calorimetry (TG-DSC) measurements. From X-ray diffraction (XRD) analysis it was observed that monophasic BiFe1-xMnxO3 samples have formed up to 25 mol% of substitution. The Rietveld analysis showed that the structure of BiFeMnO specimens can be indexed by rhombohedral or orthorhombic unit cell depending on Mn3+ content. Scanning electron microscopy (SEM) was used to investigate samples morphology and revealed, that smaller particles form when Mn3+ is present inside the structure. Moreover, magnetic properties of solid solutions were also investigated, and antiferromagnetism and weak ferromagnetism were observed for the samples.

Effect of Co-doping in V2O5 nanoparticles synthesized via a gelatin-based sol-gel method

The V2-xCoxO5 nanoparticles with Co concentrations up to x = 0.2 were synthesized via a rather facile sol-gel route in gelatin medium. The effect of Co substitution was investigated on the microstructural, optical and magnetic characteristics of the synthesized particles using X-ray diffractometer, transmission electron microscope, UV–vis diffuse reflectance spectroscope and vibrating sample magnetometer. The results showed that the synthesized particles consist mainly of crystalline α-V2O5 phase. The orthorhombic unit cell expands and the particle size increases from about 34 to 49 nm with Co content. It was found that the synthesized V2O5:Co nanoparticles are direct band gap semiconductors whose band gap energies obtained in the range of 2.92–3.09 eV are controlled by the surface and interface effects rather than the chemical composition. The low Co substitution destroys the ferromagnetic nature of the pristine V2O5 sample by decreasing the oxygen vacancies being the probable origin of the observed ferromagnetism. However, the higher Co concentrations go for its restore as a result of the dominant effect of their magnetic moment.