Structural,magnetic and Mössbauer spectroscopic investigations of the magnetoelectric relaxor Pb(Fe0.6W0.2Nb0.2)O3

The complex perovskite lead iron tungsten niobium oxide, Pb(Fe_0.6W_0.2Nb_0.2)O₃ (PFWN) which belongs to the class of disordered magnetoelectrics, has been studied by X-ray and neutron powder diffraction, magnetic and Mössbauer spectroscopic measurements. Structural, dielectric and magnetic properties of PFWN are presented and reviewed. Magnetic measurements indicate that the most important interactions are of antiferromagnetic nature yielding T_N = 300 K, however, with indications of a reentrant spin glass behaviour below 20 K. The parameters of Mössbauer spectra also support the existence of the magnetic order and are consistent with the presence of high-spin Fe³⁺ cations located in the octahedral B-site. Rietveld refinements of diffraction data at different temperatures between 10 and 700 K have been carried out. The long-range structure of PFWN is cubic (space group Pm−3m) over the whole temperature interval. The Fe, W and Nb cations were found to be disordered over the perovskite B-sites. The Pb cations show a position disorder along the 〈111〉 direction shifting from their high-symmetry position. At the temperatures below T_N, an antiferromagnetic arrangement of the magnetic moments of Fe³⁺ cations in the B-site is proposed in accordance with the antiferromagnetic properties of PFWN. The factors governing the observed nuclear and magnetic structures of PFWN are discussed and compared with those of pure Pb(Fe_0.67W_0.33)O₃, Pb(Fe_0.5Nb_0.5)O₃ and other quaternary Pb-based perovskites containing iron.     

Synthesis and magnetoelectric studies on Na0.5Bi0.5TiO3–BiFeO3 solid solution ceramics

Polycrystalline ceramics of 1 ? x[Na_0.5Bi_0.5TiO₃] ? x[BiFeO₃] (NBT–BFO) were synthesized by the modified Pechini's method to study their magnetic and magnetoelectric properties. A series of solid solutions exhibiting magnetoelectric output were formed when two iso-structural compounds Na_0.5Bi_0.5TiO₃ (NBT) and BiFeO₃ (BFO) were combined. Polarization-electric field hysteresis loops revealed that the maximum polarization (～23 μC/cm² for x = 0.1) decreased continuously with the increase of BFO content, following a hard doped effect. Piezoelectric charge coefficient (d₃₃) = 41 pC/N was obtained for the ceramics with x = 0.1 and the value continues to decrease with the composition. Magnetic hysteresis loops represent the canted antiferromagnetic nature for x ≤ 0.6 and ferromagnetic-like behavior for the BFO-rich compositions. Magnetoelectric coupling was determined by measuring the magnetoelectric voltage coefficient which is ～12.4 mV/cm-Oe at an ac magnetic field of 10 Oe (1 kHz), for x = 0.1 sample.     

Redox behavior and transport properties of La0.5−2xCexSr0.5+xFeO3−δ and La0.5−2ySr0.5+2yFe1−yNbyO3−δ perovskites

The effects of doping the mixed-conducting (La,Sr)FeO_3−δ system with Ce and Nb have been examined for the solid-solution series, La_0.5−2xCe_xSr_0.5+xFeO_3−δ (x = 0–0.20) and La_0.5−2ySr_0.5+2yFe_1−yNb_yO_3−δ (y = 0.05–0.10). Mössbauer spectroscopy at 4.1 and 297 K showed that Ce⁴⁺ and Nb⁵⁺ incorporation suppresses delocalization of p-type electronic charge carriers, whilst oxygen nonstoichiometry of the Ce-containing materials increases. Similar behavior was observed for La_0.3Sr_0.7Fe_0.90Nb_0.10O_3−δ at 923–1223 K by coulometric titration and thermogravimetry. High-temperature transport properties were studied with Faradaic efficiency (FE), oxygen-permeation, thermopower and total-conductivity measurements in the oxygen partial pressure range 10⁻⁵–0.5 atm. The hole conductivity is lower for the Ce- and Nb-containing perovskites, primarily as a result of the lower Fe⁴⁺ concentration. Both dopants decrease oxide-ion conductivity but the effect of Nb-doping on ionic transport is moderate and ion-transference numbers are higher with respect to the Nb-free parent phase, 2.2 × 10⁻³ for La_0.3Sr_0.7Fe_0.9Nb_0.1O_3−δ cf. 1.3 × 10⁻³ for La_0.5Sr_0.5FeO_3−δ at 1223 K and atmospheric oxygen pressure. The average thermal expansion coefficients calculated from dilatometric data decrease on doping, varying in the range (19.0–21.2) × 10⁻⁶ K⁻¹ at 780–1080 K.     

Structural changes produced during heating of the fast ion conductor Li0.18La0.61TiO3. A neutron diffraction study

The doubled perovskite structure (2a_p, 2a_p, 2a_p) of the fast ionic conductor Li_0.18La_0.61TiO₃ was investigated between 5 and 773 K by powder neutron diffraction. The Rietveld refinement of this orthorhombic (Cmmm Space Group) perovskite showed that at low temperature, La and vacancy rich planes alternate along [001] direction, and TiO₆ octahedra were out-of-phase tilted around the b-axis. As temperature increased, the octahedral tilting decreased and the structure approaches, at about 773 K, that of the tetragonal phase, a, a_p, 2a_p (P4/mmm Space Group). In the temperature range of the study, the La-vacancy distribution remained unchanged, but LaO₁₂ cuboctahedra became more regular. In the tetragonal phase the elimination of this tilting favors the two-dimensional motion of lithium in alternate ab-planes of the perovskite.     

Quadruple-layered perovskite (CuCl)Ca2NaNb4O13

We will present the synthesis, structure and magnetic properties of a new quadruple-layered perovskite (CuCl)Ca₂NaNb₄O₁₃. Through a topotactic ion-exchange reaction with CuCl₂, the precursor RbCa₂NaNb₄O₁₃ presumably having an incoherent octahederal tliting changes into (CuCl)Ca₂NaNb₄O₁₃ with a 2a_p×2a_p×2c_p superstructure (tetragonal; a=7.73232(5) Å, c=39.2156(4) Å). The well-defined superstructure for the ion-exchanged product should be stabilized by the inserted CuCl₄O₂ octahedral layers that firmly connect with neighboring perovskite layers. Magnetic studies show the absence of long-range magnetic ordering down to 2 K despite strong in-plane interactions. Aleksandrov′s group theory and Rietveld refinement of synchrotron X-ray diffraction data suggest the structure to be of I4/mmm space group with in-phase tilting along the a and b axes, a two-tilt system (++0).     

Fabrication and properties of Mn0.5Zn0.5Fe2O4 nanofibers

Zn-doped α-FeOOH nanofiber was synthesized by coprecipitation method. Then the α-FeOOH was enwraped by the complex of the Mn²⁺ and citric acid. The morphology of α-FeOOH did not transform after the calcination process and Mn_0.5Zn_0.5Fe₂O₄ nanofiber was successfully prepared. The phase, morphology, particle diameter and the magnetic properties of samples were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The results indicated that Mn_0.5Zn_0.5Fe₂O₄ nanofibers with an aspect ratio over 40 and a diameter of 20 nm were prepared. Compared with the amorphous Mn_0.5Zn_0.5Fe₂O₄, the anisotropy of the Mn_0.5Zn_0.5Fe₂O₄ nanofiber increased, resulting in the higher coercivity and magnetization of the obtained sample. With an increase in the calcination temperature, the diameter and the saturation magnetization of the sample increased, while the aspect ratio and coercivity decreased. The coercivity of the sample obtained at 700 °C was maximal (up to 185.4 Oe). The saturation magnetization of the sample obtained at 900 °C was maximal (up to 65.3 emu/g). The use of citric acid method prevented the presence of Mn(OH)₂, resulting in the decrease of the calcination temperature.     

Crystal and magnetic structures of electrochemically delithiated Li1−xCoPO4 phases

Precise structural data have been determined from a combined Rietveld refinement, based on neutron and X-ray powder diffraction data simultaneously, for the three phases LiCoPO₄, Li_zCoPO₄ with a specific intermediate Li-content z = 0.60(10) and CoPO₄, which are obtained by electrochemical Li-extraction from LiCoPO₄. All three phases are isopointal. Therefore, the transitions between these phases are necessarily of first order, in agreement with their observed coexistence. The same collinear antiferromagnetic structures with magnetic moments nearly parallel to the [010] direction are observed for LiCoPO₄ and Li_zCoPO₄, but with a significantly higher Néel temperature of 76 K for the latter compound in comparison with 23 K for LiCoPO₄. Olivine-type CoPO₄ can only be prepared from LiCoPO₄ by delithiation and its physical properties were investigated for the first time. An antiferromagnetic arrangement along the [100] direction is observed for CoPO₄ with an additional weak ferromagnetic component along the [001] direction (magnetic space group Pn′m′a and T_C = 45 K). The magnetic moment of 3.1(2) μ_B per Co-ion indicates a mainly high-spin state for Co³⁺ in the octahedral coordination of CoPO₄, which is exceptional and probably the first example in a phosphate. The easy axes and the magnetic exchange interactions between Co-ions change dramatically with the Co²⁺ ? Co³⁺ transition. A continuous change of the formal oxidation state of a transition element by electrochemical Li-extraction and a quasi-continuous in situ observation of the resulting magnetic structure by neutron diffraction appear feasible.     

Subsolidus phase relations,crystal chemistry and cation-transport properties of sodium iron antimony oxides

Subsolidus phase relations in Na₂O–Fe₂O₃–Sb₂O_x system (excluding Na-rich and Sb-rich corners) were studied using powder X-ray diffraction. Samples were prepared by conventional solid-state reactions at 980–1030 °C followed by quenching. Sb substitution for Fe stabilizes the low-temperature rhombohedral α form of NaFeO₂ and enhances ionic conductivity: σ(300 °C) = 0.5 S/m, E_a = 0.38(3) eV, t_e < 0.01 for Na_0.8Fe_0.9Sb_0.1O₂ ceramics. Besides known orthorhombic Na₂Fe₃SbO₈, three new compounds have been identified: trigonal Na₄FeSbO₆, a superlattice of α-NaFeO₂ type, a = 5.4217(7) Å, c = 16.2715(1) Å, possible space group P3₁12; orthorhombic Na₂FeSbO₅, possibly related to brownmillerite, Pbcn, a = 10.8965(13) Å, b = 15.7178(13) Å, c = 5.3253(4) Å, and one more phase with empirical formula Na₄Fe₃SbO₉, whose pattern could not be indexed. Ion-exchange reactions lead to a delafossite-type superlattice Ag₃(NaFeSb)O₆ (a = 5.4503(12) Å, c = 18.7747(20) Å, possible space group P3₁12).     

Double perovskite Sr2FeMoO6−xNx (x=0.3, 1.0) oxynitrides with anionic ordering

Two new oxynitride double perovskites of composition Sr₂FeMoO_6?xN_x (x=0.3, 1.0) have been synthesized by annealing precursor powders obtained by citrate techniques in flowing ammonia at 750 °C and 650 °C, respectively. The polycrystalline samples have been characterized by chemical analysis, x-ray and neutron diffraction (NPD), Mössbauer spectroscopy and magnetic measurements. They exhibit a tetragonal structure with a=5.5959(1) Å, c=7.9024(2) Å, V=247.46(2) Å³ for Sr₂FeMoO_5.7N_0.3; and a=5.6202(2) Å, c=7.9102(4) Å, V=249.85(2) Å³ for Sr₂FeMoO₅N; space group I4/m, Z=2. The nitridation process seems to extraordinarily improve the long-range Fe/Mo ordering, achieving 95% at moderate temperatures of 750 °C. The analysis of high resolution NPD data, based on the contrast existing between the scattering lengths of O and N, shows that both atoms are located at (O,N)2 anion substructure corresponding to the basal ab plane of the perovskite structure, whereas the O1 site is fully occupied by oxygen atoms. The evolution of the 〈Fe–O〉 and 〈Mo–O〉 distances suggests a shift towards a configuration close to Fe⁴⁺(3d⁴, S=2):Mo⁵⁺(4d¹, S=1/2). The magnetic susceptibility shows a ferrimagnetic transition with a reduced saturation magnetization compared to Sr₂FeMoO₆, due to the different nature of the magnetic double exchange interactions through Fe–N–Mo–N–Fe paths in contrast to the stronger Fe–O–Mo–O–Fe interactions. Also, the effect observed by low-temperature NPD seems to reduce the ordered Fe moments and enhance the Mo moments, in agreement with the evolution of the oxidation states, thus decreasing the saturation magnetization.     

Magnetic dilution effect on the charge transfer phase transition and the ferromagnetic transition for an iron mixed-valence complex, (n-C3H7)4N[FeII1−xZnIIxFeIII(dto)3] (dto = C2O2S2)

Iron mixed-valence complex, (n-C₃H₇)₄N[Fe^IIFe^III(dto)₃] (dto = C₂O₂S₂) shows a new-type of phase transition coupled with spin and charge around 120 K, where the charge transfer between the Fe^II and Fe^III sites occurs reversibly, and shows the ferromagnetic transition at 7 K. To investigate the magnetic structure and its dimensionality of (n-C₃H₇)₄N[Fe^IIFe^III(dto)₃], we have synthesized a mixed crystal system, (n-C₃H₇)₄N[Fe^II_1?xZn^II_xFe^III(dto)₃], and measured its magnetic properties. In this system, the magnetic moment is reduced with increasing of Zn ratio. Moreover, the ferromagnetic interaction changes to the antiferromagnetic one and the remnant magnetization disappears between x = 0.48 and 0.96, while the charge transfer between the Fe^II and Fe^III sites disappears above x = 0.26. In this paper, we present the magnetic dilution effect on the charge transfer phase transition and the ferromagnetic transition by means of magnetic susceptibility measurement and ⁵⁷Fe Mössbauer spectroscopy.     

Structural and magnetic study of RFe0.5V0.5O3 (R=Y, Eu, Nd, La) perovskite compounds

B-site disordered RFe_0.5V_0.5O₃ compounds, with R=La, Nd, Eu and Y, have been prepared by solid-state reaction technique and their structures and magnetic properties have been investigated through X-ray powder diffraction, time-of-flight neutron powder diffraction and magnetization measurements at temperatures ranging from 5 to 700 K. The four compounds can be described as distorted perovskites with space group symmetry Pbnm and a⁺b⁻b⁻ tilt system. The studied compounds also show antiferromagnetic ordering with Neel temperatures of 299, 304, 304, and 335 K respectively. The magnetic structures of R=La, Nd and Y compounds were determined from the neutron powder diffraction as G_z with observed magnetic moments of 2.55, 2.54 and 2.69μ_B at 30, 40 and 40 K, respectively.     

First principles study of structure and properties of La- and Mn-modified BiFeO3

First principles calculations have been performed to study the effects of the La³⁺ and Mn³⁺ substitutions in the multiferroic BiFeO₃. The real compositions Bi_1−xLa_xFeO₃ and BiFe_1−xMn_xO₃ with x = 0.0, 0.1, 0.2, 0.3 were modeled by substitution of one, two and three Bi³⁺ or Fe³⁺ by La³⁺ or Mn³⁺ in the orthorhombic BiFeO₃ structure, respectively. Density functional theory within the generalized gradient approximation with Hubbard correction of Dudarev (GGA + U) and plane wave pseudo-potential approach has been used to track the changes that occur in the structural parameters, electronic structure, magnetic, optical and polarization properties of the modified BiFeO₃. The substitution of one Bi³⁺ with La³⁺ increases the band gap energy whereas the augmentation of La³⁺ substitutes decreases it. The substitutions of Fe³⁺ with Mn³⁺ do not change the band gap energy. The calculations predicted larger polarization of the modified BiFeO₃, antiferromagnetism for Bi_1−xLa_xFeO₃ and small ferrimagnetism for BiFe_1−xMn_xO₃. Better multiferroic properties are expected for BiFe_1−xMn_xO₃ materials (x = 0.1, 0.2) due to the increasing polarization and ferrimagnetic behavior. The optical properties were estimated by the calculated imaginary and real parts of the dielectric function. The increase of La³⁺ and Mn³⁺ substitutes lead to lower absorption intensity at energy range 2–7 eV.     

Synthesis,structure and properties of Ag2PdO2

The first silver palladium oxide, Ag₂PdO₂, was synthesised from a co-precipitated oxide precursor by annealing at 423–823 K, applying an oxygen pressure of 73 MPa. The crystal structure has been determined from X-ray and neutron powder diffraction data. The new compound crystallises in space group Immm. The lattice constants as determined from X-ray powder diffraction are a=4.55523(5) Å, b=3.00803(3) Å and c=9.8977(1) Å. The crystal structure constitutes a new structure type showing some features in common with the Li₂CuO₂-type. Palladium is found in a nearly square planar arrangement while silver has an almost linear co-ordination. The overall structure can be considered as a rocksalt defect structure. Ag₂PdO₂ is diamagnetic and semiconducting. The band gap, estimated from conductivity measurements in the temperature range of 240–300 K, is 0.18(2) eV.     

Ion–electron transport in strontium ferrites: relationships with structural features and stability

The total electrical conductivity of strontium ferrites, including intergrowth Sr₄Fe₆O_13+δ, Sr₃Fe₂O_6+δ with a Ruddlesden–Popper structure, and SrFeO_2.5+δ where the cubic perovskite lattice transforms into vacancy-ordered brownmillerite at p(O₂)<10 Pa and T<850 °C, was measured at 650–1000 °C in the oxygen partial pressure range 10⁻¹⁵ Pa to 50 kPa. The data were used in order to determine partial ion, p- and n-type electron contributions in the vicinity of electron–hole equilibrium point. The ferrites with brownmillerite and Ruddlesden–Popper structures exhibit substantial ion transport due to thermally-activated disordering of oxygen vacancies and oxygen ions in the perovskite structural slabs, whereas the ion conductivity of Sr₄Fe₆O_13+δ remains below 0.01 S cm⁻¹ in the studied conditions. The bonding energy of oxygen ions, evaluated from the formation enthalpy of n-type charge carriers, increases in the sequence Sr₄Fe₆O_13+δ<SrFeO_3+δ<Sr₃Fe₂O_6+δ. These values correlate with thermodynamic stability of strontium ferrites at low p(O₂). The transition of SrFeO_2.5+δ brownmillerite into disordered cubic phase above 850 °C leads to higher stability in reducing atmospheres. The level of p-type conductivity is mainly governed by the concentration of electron holes, which was calculated from the oxygen content determined by coulometric titration technique. The hole mobility, which is quite similar for all strontium ferrites and has a temperature-activated character, varies in the range 0.005–0.05 cm² V⁻¹ s⁻¹ indicative of small-polaron conduction mechanism.     

Structures,thermal expansion properties and phase transitions of ErxFe2−x(MoO4)3 (0.0 ≤ x ≤ 2.0)

Structures, thermal expansion properties and phase transitions of Er_xFe_2−x(MoO₄)₃ (0.0 ≤ x ≤ 2.0) have been investigated by X-ray diffraction and differential thermal analysis. The partial substitution of Er³⁺ for Fe³⁺ induces pronounced decreases in the phase transition temperature from monoclinic to orthorhombic structure. Rietveld analysis of the XRD data shows that both the monoclinic and orthorhombic Fe₂(MoO₄)₃, as well as the orthorhombic Er_xFe_2−x(MoO₄)₃ (x ≤ 0.8) have positive thermal expansion coefficients. However, the linear thermal expansion coefficients of Er_xFe_2−x(MoO₄)₃ (x = 0.6–2.0) decrease with increasing content of Er³⁺ and for x ≥ 1.0, compounds Er_xFe_2−x(MoO₄)₃ show negative thermal expansion properties. Attempts for making zero thermal expansion coefficient materials result in that very low negative thermal expansion coefficient of −0.60 × 10⁻⁶/°C in Er_1.0Fe_1.0(MoO₄)₃ is observed in the temperature range of 180–400 °C, and zero thermal expansion is observed in Er_0.8Fe_1.2(MoO₄)₃ in the temperature range of 350–450 °C. In addition, anisotropic thermal expansions are found for all the orthorhombic Er_xFe_2−x(MoO₄)₃ compounds, with negative thermal expansion coefficients along the a axes.     

Structure and properties of α-AgFe2(MoO4)3

Silver diiron tris(oxomolybdate), α-AgFe₂(MoO₄)₃, was synthesized in sealed silica tubes at 1050 K and is isostructural to α-NaFe₂(MoO₄)₃, determined by single-crystal X-ray diffraction (space group P?1, a = 6.9320(7) Å, b = 6.9266(6) Å, c = 10.9732(13) Å, α = 81.197(8)°, β = 83.456(9)°, γ = 81.352(8)° at 300 K, Z = 2). The crystal structure is built up from both monomers and edge-sharing dimers of [FeO₆]-octahedra, which are linked with each other by isolated [MoO₄]-tetrahedra to a three-dimensional network. Ag ions are situated on a site with four near oxygen neighbours. Thermal expansion is most pronounced along the c-axis, while the angle α decreases with increasing temperature. Antiferromagnetic ordering is indicated by a sharp maximum in the temperature dependence of magnetization at 21.5(5) K, and a magnetic moment of 5.36(1) μ_B per Fe-ion was derived from the Curie constant in the paramagnetic region. The collinear antiferromagnetic structure with propagation vector k = (0,½,½) and an ordered magnetic moment of 4.62(9) μ_B per Fe-ion were deduced from neutron powder diffraction data and give evidence for an underlying magnetic interaction mechanism, resulting in rather strong and long-ranged couplings. Mössbauer spectroscopy shows a change in the electronic configuration on the two distinct Fe sites between room temperature and 150 K, accompanied by an increase of the average Fe–O distance for one site and a shrinking one for the other as expected for charge ordering in a mixed valence compound with Fe(II) and Fe(III).     

Effects of NiO addition on the structure and electric properties of Dy3−xNixFe5O12 garnet ferrite

Polycrystalline garnet ferrites Dy_3?xNi_xFe₅O₁₂ with varying Ni substitutions (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) have been prepared by the standard ceramic technique and their crystalline structures were investigated by using X-ray diffraction and IR spectroscopy. The X-ray diffraction analysis showed that all samples have a single cubic garnet phase. The materials prepared are identified by infrared rays which indicate the presence of three absorption bands ν₂, ν₃ and ν₄ which represent the tetrahedral, octahedral and dodecahedral sites respectively which characterize the garnet ferrite.The dielectric constant (?), and dielectric loss (tan δ) of the prepared samples were measured at 1 kHz in the temperature range 300–700 K. The dielectric constant (?), and dielectric loss (tan δ) are functions of temperature.The initial magnetic permeability has been studied at different temperatures. The initial magnetic permeability (μ_i) increases gradually with increasing temperature and then drops suddenly at a certain temperature T_c.     

Synthesis and electrical properties of (LiCo3/5Fe1/5Mn1/5)VO4 ceramics

(LiCo_3/5Fe_1/5Mn_1/5)VO₄ ceramic was synthesized via solution-based chemical method. X-ray diffraction analysis was carried out on the synthesized powder sample at room temperature, which confirms the orthorhombic structure with the lattice parameters of a = 10.3646 (20) Å, b = 3.7926 (20) Å, c = 9.2131 (20) Å. Field emission scanning electron microscopic analysis was carried out on the sintered pellet sample that indicates grains of unequal sizes (～0.1 to 2 μm) presents average grains size with polydisperse distribution on the surface of the ceramic. Complex impedance spectroscopy (CIS) technique is used for the study of electrical properties. CIS analysis identifies: (i) grain interior, grain boundary and electrode–material interface contributions to electrical response (ii) the presence of temperature dependent electrical relaxation phenomena in the ceramics. Detailed conductivity study indicates that electrical conduction in the material is a thermally activated process. The variation of A.C. conductivity with frequency at different temperatures obeys Jonscher's universal law.     

Distorted perovskite structured organic–inorganic hybrid compounds for possible multiferroic behavior: [n-alkyl]2FeCl4

Perovskite structured compounds have shown multifunctional properties and therefore attracted attention recently because of their potential applications. To explore such materials we have prepared simple double salts, distorted perovskite structured compounds, Cn₂FeCl₄, Cn = n-propyl or n-butyl ammonium ions. (C₃)₂FeCl₄ crystallize in orthorhombic space group, Cmc2₁, having lattice constants a = 7.223(9) Å, b = 7.439(9) Å, c = 25.303(8) Å with unit cell volume of 1359.95 cm³, at room temperature. The overall structure consists of two-dimensional Fe(II)–chloride network, parallel to the ac-plane, interlayered by the ammonium ions. Magnetic measurements using SQUID magnetometer show that these compounds are antiferromagnets with T_N ～ 90 K. Preliminary studies using DSC and AC-conductivity have shown promising transitions above room temperature.     

A powder neutron diffraction study of the metallic ferromagnet Co3Sn2S2

Variable-temperature powder neutron diffraction data reveal that Co₃Sn₂S₂ crystallizes in the shandite structure (space group $R\overline{3}m$, a = 5.36855(3) Å, c = 13.1903(1) Å at 300 K). The structural relationship between Co₃Sn₂S₂ and the intermetallic compound CoSn, both of which contain Kagomé nets of cobalt atoms, is discussed. Resistivity and Seebeck coefficient measurements for Co₃Sn₂S₂ are consistent with metallic behaviour. Magnetic susceptibility measurements indicate that Co₃Sn₂S₂ orders ferromagnetically at 180(10) K, with a saturation moment of 0.29 μ_B per cobalt atom at 5 K. The onset of magnetic ordering is accompanied by marked anomalies in the electrical transport properties.