Temperature-dependent Paramagnetism Research Articles

High-Pressure Synthesis and Magnetic and Electrical Properties of Fe-Doped Bi3Re3O11 and Bi3Os3O11

Under high-pressure and high-temperature conditions, doped Bi3Re3O11 and Bi3Os3O11 with Fe up to 29 atomic % were synthesized. The crystal structures and chemical compositions of Bi3Os2.45Fe0.55O11 and Bi3Re2.13Fe0.87O11 were determined by synchrotron powder X-ray diffraction and electron probe microanalysis. Both crystal structures were explained by a KSbO3-type model with the space group Pn3̅. Magnetic and electronic transport property measurements showed that Bi3Os2.45Fe0.55O11 exhibited a ferrimagnetic transition at the highest magnetic ordering temperature of 490 K in the KSbO3-type, while Bi3Re2.13Fe0.87O11 exhibited a spin glassy behavior below 22 K. The magnetoresistance at 5 K and 90 kOe was almost zero for Bi3Os2.45Fe0.55O11, but -10% for Bi3Re2.13Fe0.87O11. These results suggest that KSbO3- type 5d oxides, which exhibit only weak temperature-dependent paramagnetism to date, are a group of compounds that can be converted into spintronic materials by doping with 3d elements, leading to the development of new KSbO3-type materials with both theoretical and practical significance.

On the constitution and thermodynamic modeling of the phase diagrams Nb-Mn and Ta-Mn

The constitution of the two phase diagrams Nb-Mn and Ta-Mn has been determined from light optical and transmission and scanning electron microscopy (LOM, TEM and SEM) with energy dispersive (EDX) as well as wavelength dispersive (WDX) X-ray spectroscopy, X-ray powder (XPD) and single crystal diffraction (XSCD), differential thermal analysis (DTA) and/or differential scanning calorimetry (DSC). The Laves phases NbMn2 and TaMn2 are the only binary compounds in these systems. High-temperature differential thermal analyses revealed congruent melting for NbMn2 with Tm(NbMn2) = 1515 ± 15 °C, whereas TaMn2 melts incongruently with Tm(TaMn2) = 1797 ± 40 °C close to a depleted peritectic reaction. Both Laves phases engage in eutectic reactions ℓ ↔ (Mn) + Nb(Ta)Mn2 (Teut = 1220 ± 10 °C at 4.9 at% Nb and Teut = 1234 ± 10 °C at 0.7 at% Ta, respectively). NbMn2 also forms a eutectic with (Nb): ℓ ↔ (Nb) + NbMn2 at Teut = 1493 ± 15 °C and 53.2 at% Nb. Mn shows remarkably large maximum solid solubilities of 19.4 at% Mn in (Nb) as well as of 21.3 at% Mn in (Ta). Detailed atom site distribution has been established for the Laves phases by means of temperature dependent X-ray single crystal data (both C14 - MgZn2-type). Combined data from XPD, EDX/WDX and SEM microstructure indicate that for both Laves phases extended homogeneity regions exist: Nb1+xMn2−x (62.5–73.0 at% Mn at 950°C: −0.19≤x≤0.125) and Ta1+xMn2−x (59.5–68.5 at% Mn: −0.055≤x≤0.215). Density functional theory (DFT) calculations favor Nb(Ta)/Mn antisite occupation rather than defects. The phases, “NbMn” and “TaMn”, adopted earlier in the literature as binary system inherent compounds, were shown (TEM, WDX electron microprobe data and X-ray Rietveld refinements) to be oxygen stabilized phases of the Ti4Ni2O type (so-called eta(η)-phases) with modified Nb(Ta)/Mn site substitution to comply with the formula Nb(Ta)3−xMn3+xO1−y (defect η-W3Fe3C-type). From magnetic susceptibility and magnetization measurements, both oxide stabilized eta phases η-Nb3Mn3O1−y and η-Ta3Mn3O1−y were found to order ferromagnetically below Tc ~ 77 K, but the Laves phases NbMn2, TaMn2 reveal weakly temperature dependent paramagnetism. No trace of the rhombohedral μ-phase (W6Fe7-type) has been encountered in our investigation of the two binary phase diagrams. Thermodynamic and transport properties (specific heat, electrical resistivity and magnetic susceptibility/magnetization) classify the Laves phases with metallic behavior whilst mechanical properties (elastic moduli from DFT and nanoindentation as well as hardness and thermal expansion) group both Laves phases among rather hard and brittle intermetallics. Based on (i) the experimentally derived constitution of the Nb-Mn and Ta-Mn systems, and (ii) on new own DFT data of the energy of formation of the Laves phases, a CALPHAD (CALculation of PHAse Diagrams) calculation of both systems was made providing a complete set of optimized thermodynamic data. Furthermore, the DFT calculations provided information on the instability of the η-Ta3Mn3 structure and the atom-site specific stabilization effect of oxygen.

Ultra-small nanocluster mediated synthesis of Nd3+-doped core-shell nanocrystals with emission in the second near-infrared window for multimodal imaging of tumor vasculature

In-vivo intravital short wavelength infrared (SWIR, 1000–2300 nm) fluorescence imaging has attracted considerable attention in the imaging of tumor vasculature due to its low background, high sensitivity, and deep penetration. It can noninvasively provide dynamic feedback on the tumorigenesis, growth, necrosis and metastasis. Herein, monodisperse Nd3+-doped core-shell downconversion luminescent nanocrystals with strong emission in the second near-infrared (NIR II) window, strong temperature-dependent paramagnetism and fast attenuation to X-rays were prepared from ultra-small nanoclusters. The use of nanoclusters resulted in very uniform bright nanocrystals with a relative quantum yield comparable to the standard dye IR-26. These bright NIR nanocrystals were modified with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] to endow with excellent water-solubility, biocompatibility and a blood circulation half-life of 5.9 h. They were then successfully used to demonstrate the variation of tumor vasculature with tumor progression from tumorigenesis, growth, to necrosis in the subcutaneous breast tumor through the NIR II fluorescence imaging. They were also used as contrast agent of magnetic resonance imaging (MRI) and X-ray computed tomography (CT) imaging of tumor to provide complementary anatomic structure. Their great potential in NIR II imaging of tumor was further demonstrated with an orthotopic breast tumor. Their in-vivo biosafety was also investigated by hemanalysis and histological analyses.

Fine Tuning of Multicolored Photoluminescence in Crystalline Magnetic Materials Constructed of Trimetallic EuxTb1-x[Co(CN)6] Cyanido-Bridged Chains.

Coordination compounds built of trivalent lanthanide ions have been demonstrated as promising solid-state materials for diverse photoluminescent applications and as attractive magnetic objects with the prospective application in information storage and spintronics. We present a synthetic methodology in which both luminescent and magnetic functionalities are induced within lanthanide-based coordination polymers by the application of hexacyanocobaltate(III) anions and 3-hydroxypyridine (3-OHpy), both coordinated to 4f-metal ions modulating the lanthanide-centered properties. We report a series of trimetallic cyanido-bridged chains {[EuIIIxTbIII1-x(3-OHpy)2(H2O)4][CoIII(CN)6]}·H2O (x = 1, 0.8, 0.5, 0.4, 0.3, 0.2, 0.1, 0; compounds 1, 2, ..., 7, 8). They reveal tunable visible photoluminescence ranging from green, through yellow and orange, to red color depending on the composition of material and the wavelength of UV excitation light. Such multicolored emission is realized by the adjusted ratio between red emissive Eu3+ and green emissive Tb3+ and by the selection of wavelengths of UV light controlling the intensities of Eu- and Tb-based components of visible luminescence. The photoluminescence is enhanced by the energy-transfer (ET) process from [CoIII(CN)6]3- and 3-OHpy to lanthanides, and the efficiencies of ET to Eu and Tb play an important role in the switchable emission. The whole family, 1-8, exhibits temperature-dependent paramagnetism due to the intrinsic property of lanthanide(3+) ions. Tb-containing 2-8 reveal the field-induced slow relaxation of magnetization due to the magnetic anisotropy of Tb3+. Moreover, the compounds built of large amounts of Tb reveal the double relaxation, the faster of a typical TbIII single-ion origin, and the slower originating from the magnetic dipole-magnetic dipole interactions between neighboring TbIII centers. Compound 2, which can be considered as a magnetically diluted sample, exhibits almost single relaxation process with the thermal energy barrier ΔE/kB of 35.8(6) K and τ0 = 1.1(2) × 10-8 s at Hdc = 1500 Oe, indicating a single-molecule magnet behavior.

Crystal structure and magnetism of UOsAl

Crystal structure, magnetization, and specific heat were studied on single crystal of uranium intermetallic compound UOsAl. It is a hexagonal Laves phase of MgZn2 type, space group P63/mmc, with lattice parameters a=536.4pm, c=845.3pm. Shortest inter-uranium distance 313pm (along the c-axis) is considerably smaller than the Hill limit (340pm). The compound is a weakly temperature-dependent paramagnet with magnetic susceptibility of ≈1.5*10−8m3mol−1 (at T=2K), which is slightly higher with magnetic field along the a-axis compared to the c-axis. The Sommerfeld coefficient of electronic specific heat has moderate value of γ=36mJmol−1K−2.

A little spin on the side: solvent and temperature dependent paramagnetism in [Ru(II)(bpy)2(phendione)](2+).

Solvent and temperature dependent paramagnetism is reported for the complex [Ru(II)(bpy)2(phendione)](PF6)2 (bpy = 2,2'-bipyridine, phendione = 1,10-phenanthroline-5,6-dione), . Magnetometry, (1)H-NMR, EPR and substituent effects confirm that the paramagnetic character is localized on the phendione ligand, and arises due to mixing of the MLCT excited state with an open shell triplet state on the phendione moiety, a process that is most likely driven by aromatization. The stabilized open shell phendione structure, in which the triplet lies lower in energy than the singlet, can then be thermally populated from the ground state of the complex. This process is facilitated by admixture of singlet character from the MLCT state. Paramagnetic behavior is absent in the free phendione ligand, and disappears in the presence of Lewis acids and in the presence of water due to hydrogen bonding (or hydrate formation at sufficient water concentrations). Control experiments rule out the presence of monoradicals such as semiquinone anions. Implications for spin filtering, sensing, and other electronic applications using such structures are discussed.

Cooperative transition of electronic states of antisite As defects in Be-doped low-temperature-grown GaAs layers

Magnetic properties resulting from localized spins associated with antisite arsenic ions AsGa+ in Be-doped low-temperature-grown GaAs (LT-GaAs) layers were studied by measuring the magnetization of lift-off samples. With fast cooling, the magnetization of samples at 1.8 K becomes significantly lower than that expected from Curie-type paramagnetism in the range of the applied field to 7 T, and a transition from low magnetization to the magnetization of paramagnetism occurs upon the heating of samples to 4.5 K. With slow cooling, on the other hand, samples have a paramagnetic temperature dependence throughout the measurement-temperature range. The magnetization was found to decrease monotonically when a sample was kept at a fixed low temperature. These observations are explained by the cooperative transition of electron states of AsGa defects, which is closely related to the normal-metastable state transition of EL2 defects in semi-insulating GaAs. The results of the magnetization measurements in the present study suggest that AsGa+ ions are spontaneously displaced at low temperature without photoexcitation in Be-doped LT-GaAs. The similarity of the transition observed in this system to the normal-metastable state transition of the EL2 defect was also suggested by first-principle calculations of the electron state of an AsGa defect with a doped Be atom.

Antiferromagnetic ordering in magnetic ionic liquid Emim[FeCl 4

The magnetic ionic liquids (MILs) are considered to open up a wide range of applications because of their magnetic and electrochromic switching. Until recently almost all magnetic ionic liquids containing tetrachloroferrate ion FeCl 4 − evidenced a paramagnetic temperature dependence of the magnetic susceptibility, with only small deviations from the Curie law at low temperatures. However, 1-ethyl-3-methylimidazolium tetrachloroferrate, Emim[FeCl 4], clearly exhibits a long-range antiferromagnetic ordering below the Neel temperature T N≈3.8 K. In addition, the shape of the magnetic ordering depends on the cooling speed, indicating that the magnetic coupling could be modified.

Long-range magnetic ordering in magnetic ionic liquid:Emim[FeCl4

Up to now most of the magnetic ionic liquids containing tetrachloroferrate ionFeCl4 have evidenced a paramagnetic temperature dependence of the magnetic susceptibility,with only small deviations from the Curie law at low temperatures. However, wereport on the physical properties of 1-ethyl-3-methylimidazolium tetrachloroferrateEmim[FeCl4], that clearly shows a long-range antiferromagnetic ordering below the Néel temperatureTN≈3.8 K. In addition, the field dependence of the magnetization measured at2 K is characterized by a linear behaviour up to around 40 kOe, whileabove this field the magnetization becomes saturated with a value of 4.3 μB/Fe, which is near the expected fully saturated value of 5 μB/Fe foran Fe3 + ion.

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New niobium-based misfit sulfides [(Ln1/3Sr2/3S)1.5]1.15NbS2 (Ln=Sm, Tb) have been synthesized from a mixture of SrS, Ln2S3, Nb(m), and S in evacuated and sealed silica tubes by annealing at 1000 °C for 144 h under a sulfur partial pressure of 49.3 kPa. The compounds have been characterized by EDX analysis, X-ray single crystal and powder diffraction, electron diffraction, and magnetic susceptibility measurements. Both sulfides have misfit structures with orthorhombic symmetry for the (Ln1/3Sr2/3S)1.5 (Ln=Sm, Tb) and NbS2 subsystems. The lattice parameters for the different subsystems are: for the Sm-based sulfide [(Sm1/3Sr2/3S)1.5]: a=5.7953(9) Å, b=5.8007(5) Å, c=14.957(2) Å and [NbS2]: a=3.3420(7) Å, b=5.8008(5) Å, c=14.955(2) Å, and for the Tb-based sulfide [(Tb1/3Sr2/3S)1.5]: a=5.769(2) Å, b=5.7766(7) Å, c=14.906(2) Å and [NbS2]: a=3.340(1) Å, b=5.7769(8) Å, c=14.905(2) Å. The [(Sm1/3Sr2/3S)1.5]1.15NbS2 crystal structure has been refined from X-ray single crystal data. It belongs to the 1.5Q/1H homologue type where the (Sm1/3Sr2/3S)1.5 part is a three-atoms-thick slab. Sr-cations are mainly located at the exterior of the slab whereas Sm preferably occupy the positions at its center. Both compounds exhibit paramagnetic temperature dependence down to 2 K.

Syntheses, Crystal and Band Structures, and Magnetic and Optical Properties of New CsLnCdTe3 (Ln = La, Pr, Nd, Sm, Gd−Tm, and Lu)

A series of new quaternary semiconductor materials CsLnCdTe(3) (Ln = La, Pr, Nd, Sm, Gd-Tm, and Lu) was obtained from high-temperature solid-state reactions by the reactive halide flux method. These compounds belong to the layered KZrCuS(3) structure type and crystallize in the orthorhombic space group Cmcm (No. 63). Their structure features two-dimensional infinity(2)[LnCdTe(3)-] layers of edge- and vertex-sharing LnTe(6) octahedra with Cd atoms filling the tetrahedral interstices, which stack along b-axis. The Cs atoms are located between the infinity(2)[LnCdTe(3)-] layers and are surrounded by eight Te atoms to form a CsTe(8) bicapped trigonal prism. Such Te layers are more flexible than the Se analogues in the isostructural CsLnMSe(3) to accommodate nearly the entire Ln series. Theoretical studies performed on CsTmCdTe(3) show that the material is a direct band gap semiconductor and agrees with the result from a single-crystal optical absorption measurement. Magnetic susceptibility measurements show that the CsLnCdTe(3) (Ln = Pr, Nd, Gd, Dy, Tm) materials exhibit temperature-dependent paramagnetism and obey the Curie-Weiss law, whereas CsSmCdTe(3) does not.

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New niobium-based misfit sulfides [(Ln1/3Sr2/3S)1.5]1.15NbS2 (Ln=Sm, Tb) have been synthesized from a mixture of SrS, Ln2S3, Nb(m), and S in evacuated and sealed silica tubes by annealing at 1000 °C for 144 h under a sulfur partial pressure of 49.3 kPa. The compounds have been characterized by EDX analysis, X-ray single crystal and powder diffraction, electron diffraction, and magnetic susceptibility measurements. Both sulfides have misfit structures with orthorhombic symmetry for the (Ln1/3Sr2/3S)1.5 (Ln=Sm, Tb) and NbS2 subsystems. The lattice parameters for the different subsystems are: for the Sm-based sulfide [(Sm1/3Sr2/3S)1.5]: a=5.7953(9) Å, b=5.8007(5) Å, c=14.957(2) Å and [NbS2]: a=3.3420(7) Å, b=5.8008(5) Å, c=14.955(2) Å, and for the Tb-based sulfide [(Tb1/3Sr2/3S)1.5]: a=5.769(2) Å, b=5.7766(7) Å, c=14.906(2) Å and [NbS2]: a=3.340(1) Å, b=5.7769(8) Å, c=14.905(2) Å. The [(Sm1/3Sr2/3S)1.5]1.15NbS2 crystal structure has been refined from X-ray single crystal data. It belongs to the 1.5Q/1H homologue type where the (Sm1/3Sr2/3S)1.5 part is a three-atoms-thick slab. Sr-cations are mainly located at the exterior of the slab whereas Sm preferably occupy the positions at its center. Both compounds exhibit paramagnetic temperature dependence down to 2 K.

The intercalation of transition metal salen complexes into layered MoS2

Exfoliation-restack method has been employed to synthesize the intercalation compounds based on the cationic complexes [M(Salen)]+ (M = Mn3+, Fe3+, Co3+; Salen = N, N′-ethylene-bis(salicylaldimine)) into the layered MoS2. Their conductivity is in the range of 0.04–0.1 S/cm, which is much higher than the pristine MoS2. Magnetic measurement indicated that the intercalation compounds [Mn(Salen)]0.18MoS2 · 0.25H2O and [Fe(Salen)]0.12MoS2 · 0.3H2O exhibit the temperature-dependent paramagnetism, which obviates from the Curie–Weiss law due to the temperature-independent paramagnetism of the exfoliated MoS2 slabs, while [Co(Salen)]0.14MoS2 · 0.5H2O exhibits the almost temperature-independent paramagnetism. All three intercalation compounds do not show magnetic spin crossover behavior.

Orbital Interactions in Fe(II)/Co(III) Heterobimetallocenes: Single versus Double Bridge

Ferrocenyl cobaltocenium hexafluorophosphate (1) and ferrocenylene cobaltocenylenium hexafluorophosphate (2) are investigated by a range of spectroscopic methods. Both compounds are diamagnetic, in contrast to an earlier report indicating a temperature-dependent paramagnetism of 2. Electronic absorption spectra of 1 and 2 are presented and fully assigned up to 50 000 cm(-1) on the basis of electronic structure (DFT) calculations and spectral comparisons with ferrocene and cobaltocenium. The lowest-energy bands, I, of both 1 and 2 correspond to metal-to-metal CT (MMCT) transitions; further intermetallocene charge-transfer bands are identified at higher energy (bands III and V). On the basis of the spectroscopic properties, a trans geometry and a twisted structure are derived for 1 and 2, respectively, in solution. Analysis of the I bands gives orbital mixing coefficients, alpha, electronic-coupling matrix elements, V(AB), and reorganization energies, lambda. Importantly, alpha and V(AB) are larger for 1 than for 2 (0.07 and 1200 cm(-1) vs 0.04 and approximately 600 cm(-1), respectively), apparently in contrast to the presence of one bridge in 1 and two bridges in 2. This result is explained in terms of the respective electronic and geometric structures. Reorganization energies are determined to be 7600 cm(-1) for 1 and 4600 cm(-1) for 2, in qualitative agreement with the analogous Fe(II)-Fe(III) compounds. The general implications of these findings with respect to the spectroscopic and electron-transfer properties of bimetallocenes are discussed.

Influence of structural disorder on magnetic and transport properties of (La0.7Sr0.3)0.5(Pr0.65Ca0.35)0.5MnO3 films

Magnetic and transport properties of (La0.7Sr0.3)0.5(Pr0.65Ca0.35)0.5MnO3 films prepared by a “co-deposition” utilizing the laser-ablation technique are investigated in a wide temperature range. The film deposited at 300 °C has a nanocrystalline disordered structure and exhibits a paramagnetic temperature dependence of the magnetization with a narrow peak (ΔT≃10 K) at TG≃45 K, which can be interpreted as a paramagnetic→superparamagnetic transition. A short-term annealing of the as-deposited film at 750 °C leads to the formation of a high-textured polycrystalline microstructure and to the appearance of ferromagnetic (FM) and metal–insulator (MI) transitions at TC≃240 K and TP≃140 K, respectively. The observed discrepancy between TP and TC values can be ascribed to a percolating nature of the MI transition, with an exponent of 5.3 for the percolating conductivity. The film deposited at Tsub≃740 °C is composed of lattice-strain-free and the lattice-strained crystallites with different lattice parameters and TC’s, and is consistently described in the framework of the Millis model [A. J. Millis, T. Darling, and A. Migliori, J. Appl. Phys. 83, 1588 (1998)]. For a single-phase crystalline film the values TC≃270 K and TP≃260 K are obtained.

EPR Studies of Poly(o‐Phenetidine)‐Poly(Styrenesulfonic Acid) and Poly(2‐Ethylaniline)‐Poly(Styrenesulfonic Acid) Complexes

AbstractThis study relates to electron paramagnetic resonance (EPR) of the poly(o‐phenetidine)‐poly(styrenesulfonic acid) [P(O‐P)‐PSSA] and poly(2‐ethylaniline)‐poly(styrenesulfonic acid) [P(2‐E)‐PSSA] complexes; the polyaniline [PANI], poly(o‐phenetidine) [POP], poly(2‐ethylaniline) [P2E], and polyaniline‐poly(styrenesulfonic acid) [PANI‐PSSA] were prepared to be the reference samples; the EPR spectra results were recorded at both 298 K and 77 K, and were analyzed on the basis of the polaron‐bipolaron model, which is typical for non‐degenerate systems. The EPR spectra results of the substituted polyaniline complexes P(O‐P)‐PSSA and P(2‐E)‐PSSA, show temperature‐dependent paramagnetism; the narrow line‐width arises due to polarons, and the charge transport takes place through both polarons and bipolarons. The narrower line‐width of the substituted polyaniline complexes can be attributed to the lower degree of structural disorder, the oxygen absorption of the polymer molecular complexes, and the steric effect by the alkyl group of the polyaniline; the reduced line‐widths were consistent with the lower molecular weight of the complexes.

New strontium and rare earth-based mixed niobium misfit sulfides

New niobium-based misfit sulfides [(Ln 1/3Sr 2/3S) 1.5] 1.15NbS 2 (Ln=Sm, Tb) have been synthesized from a mixture of SrS, Ln 2S 3, Nb(m), and S in evacuated and sealed silica tubes by annealing at 1000 °C for 144 h under a sulfur partial pressure of 49.3 kPa. The compounds have been characterized by EDX analysis, X-ray single crystal and powder diffraction, electron diffraction, and magnetic susceptibility measurements. Both sulfides have misfit structures with orthorhombic symmetry for the (Ln 1/3Sr 2/3S) 1.5 (Ln=Sm, Tb) and NbS 2 subsystems. The lattice parameters for the different subsystems are: for the Sm-based sulfide [(Sm 1/3Sr 2/3S) 1.5]: a=5.7953(9) Å, b=5.8007(5) Å, c=14.957(2) Å and [NbS 2]: a=3.3420(7) Å, b=5.8008(5) Å, c=14.955(2) Å, and for the Tb-based sulfide [(Tb 1/3Sr 2/3S) 1.5]: a=5.769(2) Å, b=5.7766(7) Å, c=14.906(2) Å and [NbS 2]: a=3.340(1) Å, b=5.7769(8) Å, c=14.905(2) Å. The [(Sm 1/3Sr 2/3S) 1.5] 1.15NbS 2 crystal structure has been refined from X-ray single crystal data. It belongs to the 1.5Q/1H homologue type where the (Sm 1/3Sr 2/3S) 1.5 part is a three-atoms-thick slab. Sr-cations are mainly located at the exterior of the slab whereas Sm preferably occupy the positions at its center. Both compounds exhibit paramagnetic temperature dependence down to 2 K.

Iron(II) complexes containing poly(1-pyrazolyl)methane ligands

A number of iron(II) compounds containing the poly(1-pyrazolyl)methane ligands bis(1-pyrazoyl)methane (BPM, 3), bis(3,5-dimethyl-1-pyrazolyl)methane (dmBPM, 4), and tris(1-pyrazolyl)methane (TPM, 2), were synthesised and characterised: cis-[Fe(BPM) 2Cl 2] ( 5), trans-[Fe(BPM) 2(NCS) 2] ( 9), [Fe(BPM) 2Cl] +(BPh 4) − ( 7), [Fe(dmBPM) 2Cl 2] ( 6), [Fe(dmBPM) 2Cl] +(BPh 4) − ( 8), [Fe(TPM) 2] 2+(Cl −) 2 ( 10), and [Fe(TPM)(NCS) 2] ( 11). The solid-state structures of cis-[Fe(BPM) 2Cl 2] ( 5) and trans-[Fe(BPM) 2(NCS) 2] ( 9) were determined by single crystal X-ray diffraction analysis. The compound cis-[Fe(BPM) 2Cl 2] ( 5) crystallises as colourless prisms from ethanol and trans-[Fe(BPM) 2(NCS) 2] ( 9) crystallises as colourless plates from methanol. All complexes were characterised by 1H- and 13C-NMR spectroscopy, infrared and far infrared spectroscopy, and mass spectroscopy. All of the iron(II) poly(1-pyrazolyl)methane compounds display temperature-dependent paramagnetism.

Solid solution range of boron and properties of the perovskite-type NdRh 3B

Polycrystalline samples of NdRh 3B x have been synthesized by arc melting technique. The crystal structure of NdRh 3B x is the perovskite-type cubic system (space group Pm 3 m ) for nominal boron concentration in the range of 0.706≤ x≤1.000 (15–20 mol.% B). The lattice parameter a varies linearly from 0.41749(7) nm ( x=0.706) to a=0.42136(6) nm ( x=1.000). Thermogravimetric analysis indicates that the oxidation onset temperature for NdRh 3B 1.000 is 663 K. The weight gain of the sample by heating in air up to 1473 K is 10.00% for NdRh 3B 1.000, and oxidized products are Rh and NdBO 3. The micro-Vickers hardness is 4.9±0.05 GPa for NdRh 3B 1.000. NdRh 3B 1.000 shows a metallic temperature dependence of the resistivity down to 0.5 K. Magnetic susceptibilities for NdRh 3B 1.000 show Curie-like paramagnetic temperature dependence due to Nd 3+ moments. No trace of magnetic phase transitions and superconductivity is found.

Ternary lithium nitridocuprates, Li3−x−yCuxN: crystal growth, bulk synthesis, structure and magnetic properties

Systematic studies within the ternary Li–Cu–N system have examined the effects of varying starting materials, transition metal stoichiometry, reaction temperature/duration and cooling rate on crystal growth and bulk phase formation of ternary nitridocuprates. Resulting lithium transition metal compounds, Li3−x−y□yCuxN (□=Li vacancy), have been characterised by single crystal and powder XRD. The maximum copper substituent level (x≈0.45) and vacancy level, y, appear insensitive to reaction temperature. Both vacancies and copper are disordered with Li when reaction mixtures are quenched (α-Li3N-type: P6/mmm, a≈3.7 Å, c≈3.8 Å, Z=1), whereas evidence of copper and/or vacancy ordering exists on slow cooling. Morphology of crystallites has been evaluated by SEM and magnetic properties have been investigated using squid magnetometry. Magnetic data show compounds exhibit temperature dependent paramagnetism in contrast to the parent nitride, Li3N.