Ac Susceptibility Measurements Research Articles

Structural and spin-glass properties of single crystal J eff = ½ pyrochlore antiferromagnet NaCdCo2F7: correlating T f with magnetic-bond-disorder

Weak bond disorder disrupts the expected spin-liquid ground-state of the ideal S = 1/2 Heisenberg pyrochlore antiferromagnet. Here we introduce a single crystal study of the structural and magnetic properties of the bond-disordered pyrochlore NaCdCo2F7. The magnetic susceptibility appears isotropic, with a large negative Curie-Weiss temperature (θCW = −108(1) K), however no magnetic order is observed on cooling until a spin-glass transition at T f = 4.0 K. AC-susceptibility measurements show a frequency-dependent shift of the associated cusp in χ’ at T f, that can be fitted well by the empirical Vogel-Fulcher law. The magnetic moment of μ eff = 5.4(1) μ B/Co2+ indicates a significant orbital contribution and heat capacity measurements show that down to 1.8 K, well below T f, only S mag ∼ Rln(2) of the magnetic entropy is recovered, suggestive of residual continued dynamics. Structural and magnetism comparisons are made with the other known members of the NaA’’Co2F7 family (A″ = Ca2+, Sr2+), confirming the expected relationship between spin-glass freezing temperature, and extent of magnetic bond disorder brought about by the size mismatch between A-site ions.

Orthorhombic YBa2Cu3O7−δ Superconductor with TiO2 Nanoparticle Addition: Crystal Structure, Electric Resistivity, and AC Susceptibility

This article reports the effect of a nanoscale addition of TiO2 on the structure and superconducting parameters of the high-temperature superconductor YBa2Cu3O7-δ (Y123). Polycrystalline compounds of Y123 with different percentages of TiO2, x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0, were fabricated using the thermal treatment method. An analysis using X-ray diffraction confirmed the formation of Y123 phases for all composite samples. Field-emission scanning electron microscopy (FESEM) analysis revealed the growth of grain size and decrease in porosity, with a sign of partial melting of grains for the samples with TiO2 addition. The magnetic and electric transport properties were investigated using AC susceptibility measurement and the four-probe method, respectively. It was observed that the superconducting transition temperature, Tc-onset, for a pure sample determined by ACS and 4PP was 95.6 K and 95.4 K, respectively. These values were found to decrease with the addition of TiO2, while the superconducting transition (∆Tc) improved with TiO2 addition except for the sample at x = 0.2 wt.%, which showed the broadest transition width. The sharpest superconducting transition (∆Tc) was observed for the sample at x = 1.0 wt.%, indicating that the addition of TiO2 nanoparticles is expected to serve as artificial pinning centres and strengthen the connection among the grains in the Y123 ceramic.

The Effect of a DC Magnetic Field on the AC Magnetic Properties of Oleic Acid-Coated Fe3O4 Nanoparticles.

The AC magnetic properties of a sample of Fe3O4 nanoparticles coated with oleic acid have been investigated with the help of AC susceptibility measurements. In particular, several DC magnetic fields have been superimposed on the AC field, and their effect on the magnetic response of the sample has been analysed. The results show the presence of a double peak structure in the imaginary component of the complex AC susceptibility measured as a function of the temperature. A preliminary evaluation of the Mydosh parameter for both peaks gives the information that each one of them is associated with a different state of interaction between nanoparticles. The two peaks evolve both in amplitude and position when the intensity of the DC field is changed. The field dependence of the peak position shows two different trends, and it is possible to study them in the framework of the currently existing theoretical models. In particular, a model of non-interacting magnetic nanoparticles has been used to describe the behaviour of the peak at lower temperatures, whereas the behaviour of the peak at higher temperatures has been analysed in the framework of a spin-glass-like model. The proposed analysis technique can be useful for the characterisation of magnetic nanoparticles used in several types of applications, such as biomedical and magnetic fluids.

Effect of Ni and Zn substitution on the physical and electrical properties of NdBaSrCu3O7−δ high temperature superconductor

Polycrystalline NdBaSrCu[Formula: see text]MxO[Formula: see text] samples ([Formula: see text] or Zn for [Formula: see text]) were prepared via solid-state reaction and examined by X-ray diffraction (XRD), Scanning electron microscopy (SEM), AC susceptibility and electrical resistance (dc) measurements. This study is focused on the effect of magnetic and non-magnetic particles substitution on the superconductivity of this tetragonal NdBaSrCu3O[Formula: see text] sample. There is no significant dependence of doping concentration for the changes of a-, b-lattice parameter but c-lattice parameter increased with both Ni and Zn substituted samples contrary to the ionic size considerations of the dopants. Results showed decrease of the critical temperature, [Formula: see text] and critical current density [Formula: see text] with increase of both doping contents. [Formula: see text] is the peak temperature of the imaginary part of the complex AC susceptibility, [Formula: see text]. Decrease of [Formula: see text] is related to the disruption of spin correlation of the CuO2 planes. Both doping only affect the [Formula: see text] without changing the transition width. The results showed that both Ni and Zn substitutions alter the quantity of spin-singlet pairs but have no effect on the size of the spin gap in the ladder. However, Zn doping more clearly lowered the [Formula: see text] than Ni doping. It is proposed that Zn, a non-magnetic dopant, caused a greater induction of unpaired charge carriers.

Field‐induced Co(II) single‐ion magnet with nearly perfect octahedral ligand field

AbstractIn this paper, a mononuclear Co(II) compound [Co(H2O)6]Cl2·2C6H12N4·4H2O (1) was synthesized and characterized. X‐ray single crystal diffraction analyses shows that the Co(II) ion adopts almost perfect octahedral coordination geometry with O6 donors provided by six water molecules. Magnetic properties studies show it has strong in‐plane anisotropy with D = +66.7 cm−1. AC susceptibility measurements indicate it is a field‐induced SMM with Ueff = 56.11 K via Raman relaxation process and/or direct process. It is rare for Co(II) ion in cobalt‐based compound showing almost perfect octahedral coordination geometry.

Magnetic glassy state in combination with ferromagnetism in Fe0.05(SnTe)0.97Sb0.03 bulk alloy

In this study on Fe0.05(SnTe)0.97Sb0.03 bulk alloy, we found signatures of presence of both magnetic glassy state and ferromagnetism. The bulk alloy is prepared by modified solid state technique and the sample is characterized for its structural, electrical and magnetic properties. Electrical resistivity plot shows semiconducting nature of the sample, however below 25 K, a sudden increase in the electrical resistivity value is observed. The transport mechanism is explained on the basis of small polaron hopping (SPH) model and variable range hopping (VRH) model. A large bifurcation observed between zero-field cooled and field-cooled magnetization at low temperature hints towards existence of a magnetic glassy state. M-H curve exhibits hysteresis behaviour for the measurements carried out at 10, 100 and 300 K. However, absence of saturation of the curves at 10 and 100 K suggests co-existence of ferromagnetic and glassy state. Presence of magnetic glassy state can also be confirmed from the Arrott plot and AC Susceptibility measurement. The susceptibility curves are found to undergo relatively small shift of peaks with frequency and theoretical fitting of the data supports presence of a cluster-glass state.

Effect of Subtle Changes on the Slow Relaxation Behavior of Co(II) Ions Based Metal-Organic Frameworks

Metal-organic framework (MOF) materials play an important role in coordination chemistry. Here, we report the synthesis, structure, and magnetic properties of a Co(II)-based MOF [Co(dps)2Cl2]n (1). Single-crystal diffraction analysis reveals that compound 1 has a two-dimensional (2D) layered structure. The magnetic properties studies indicate that compound 1 shows easy-plane anisotropy with positive D value, which is further proved by high-field electron paramagnetic resonance (HF-EPR). AC susceptibility measurements show that compound 1 is field-induced SMM governed by single Co(II) ion. The magnetic properties studies indicate that coordinate halogens have almost no effect on the slow magnetic relaxation time and effective energy barrier. However, the secondary coordination environment of packing pattern has a significant effect on the slow relaxation.

Canonical spin glass and cluster glass behavior in the polymorphs of LiFeSnO4

We report a comprehensive and comparative study of structural, static, dynamic, and nonequilibrium magnetic properties on the polymorphs of $\mathrm{LiFeSn}{\mathrm{O}}_{4}$. It exhibits two polymorphs: (i) orthorhombic phase (HT) stabilized at high temperature and (ii) hexagonal phase (LT) obtained at lower synthetic temperature. The HT phase crystallizes in the orthorhombic structure (space group: Pmcn) and exhibits a site disordered, nonfrustrated zig-zag network of ${\mathrm{Fe}}^{3+}$ and ${\mathrm{Sn}}^{4+}$ ions. On the other hand, the LT phase shows a disordered frustrated kagome network of ${\mathrm{Li}}^{1+}, {\mathrm{Fe}}^{3+}$, and ${\mathrm{Sn}}^{4+}$ ions crystallizing in the hexagonal structure (space group: $P{6}_{3}mc$). The low-temperature thermo-magnetic irreversibility and the absence of heat capacity anomaly in both polymorphs indicate the absence of long-range magnetic ordering and a possible glassy state. Zero-field-cooled and field-cooled magnetic memory effect and spin relaxation measurements stipulate the spin glass nature of the polymorphs. Further, spin glass behavior is confirmed by the AC susceptibility measurements. Interestingly, these polymorphs reveal different classes of spin glass states. The site disordered HT phase exhibits a single spin-flip time ${\ensuremath{\tau}}_{0}\ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}$ sec, indicating a canonical spin glass state. In contrast, LT phase, which is disordered and geometrically frustrated, shows the spin-flip time of ${\ensuremath{\tau}}_{0}\ensuremath{\sim}9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ sec, suggesting a cluster spin glass state. In addition, the exchange bias effect was observed due to magnetic inhomogeneity in both polymorphs.

Coexistence of superparamagnetism and superspin glass in non-stoichiometric Zn0.5Ca0.5Fe2O4 nanoferrite

In this manuscript, we report the coexistence of superparamagnetic-super spin glass phase in aggregated non-stoichiometric Zn0.5Ca0.5Fe2O4 ferrite nanoparticles (ZCF NPs). A polycrystalline sample of ZCF NPs was synthesized by the self-ignition sol–gel route and characterized using a variety of techniques. Extensive temperature, field and wait-time dependent dc-magnetization & ac-susceptibility measurements were performed for elucidating the magnetism of ZCF NPs. M−H & Mössbauer data at 300 K and M−T curves in ZFC & FC protocols revealed that ZCF NPs exhibit dominant superparamagnetic (SPM) character at 300 K with Ms = 16 emu/g & TB ∼ 120 K. Magnetically disordered surface over a single domain core of ZCF NPs has been established by the shift in coercivity at 5 K in ZFC and FC protocols. ZFC magnetization for a single stop and wait protocol exhibited an ageing dip at the stop temperature (72 K) with waiting time. It is shown that the in-phase peak of ac-susceptibility vs. temperature curves shifts towards higher temperature with driving frequencies and obeys dynamic scaling & Vogel-Fulcher law. These findings affirmed presence of glassy states in ZCF NPs due to interacting magnetic nanoparticles. On cooling the random ensemble of ZCF NPs, interparticle dipolar interactions lead to genesis of glassy behaviour, which is identified as superspin glass (SSG). Observation of memory and rejuvenation in a quasi-equilibrium magnetic state due to the collective nature of low-temperature spin dynamics differ ZCF NPs from canonical spin-glass. Extensive magnetic studies on ZCF NPs revealed a crossover of SPM to SSG phase just below TB at 115 K due to the random distribution of magnetic momenta, anisotropy and interparticle interactions.

Existence of exotic magnetic phases along with exchange bias and memory effect in frustrated beta-Mn Heusler alloy

Generally, Co-based Heusler alloys are the center of interest because of their properties such as high Curie temperature, spin polarization, and high value of exchange bias. Herein, we have used the macroscopic technique to probe the low-temperature exotic properties of M1.5Co0.5FeAl. First, we have analyzed the dc magnetization data, and it unfolds the presence of a glassy phase at 33 K. The cluster spin glass phase is authenticated by measuring ac susceptibility. Furthermore, using empirical models like power law and Vogel–Fulcher fitting, the relaxation time for the spin is of the order of τ ∼ 10−9 s, confirming the presence of a cluster spin glass in Mn1.5Co0.5FeAl below an irreversible temperature. The H–T phase space diagram ensures that it follows the Ising spin model. Furthermore, the glassy phase of the system is confirmed by magnetic relaxation, memory effect, and the presence of an exchange bias instead of a minor loop below spin-freezing temperature (Tf ∼ 33 K).

Observation of slow magnetic relaxation phenomena in spatially isolated π-radical ions.

The use of molecular spins as quantum bits is fascinating because it offers a wide range of strategies through chemical modifications. In this regard, it is very interesting to search for organic radical ions that have small spin-orbit coupling values. On the other hand, the feature of the magnetic relaxation of π-organic radical ions is rarely exploited due to the difficulty of spin dilution, and π-stacking interaction. In this study, we focus on N,N',N''-tris(2,6-dimethylphenyl)benzenetriimide (BTI-xy), where three xylene moieties connected to the imide groups cover the π-plane of the BTI core. As a result, BTI-xy radical anions without π-stacking interaction were obtained. This led to the slow magnetization relaxation, which is reported for the first time in organic radicals. Furthermore, the relaxation times in a solution state revealed the importance of spin interaction.

A cascade of magnetic phase transitions and a 1/3-magnetization plateau in selenite-selenate Co3(SeO3)(SeO4)(OH)2 with kagomé-like Co2+ ion layer arrangements: the importance of identifying a correct spin lattice.

We prepared a new compound, Co3(SeO3)(SeO4)(OH)2, having layers in a kagomé-like arrangement of Co2+ (spin S = 3/2) ions. This phase crystallizes in the orthorhombic space group Pnma (62) with unit cell parameters a = 11.225(9) Å, b = 6.466(7) Å and c = 11.530(20) Å. Its layers, parallel to the ab-plane, are made up of Co1O5 square pyramids and Co2O6 and Co3O6 octahedra. As the temperature is lowered, Co3(SeO3)(SeO4)(OH)2 undergoes three successive magnetic transitions at 27.5, 19.4 and 8.1 K, and the magnetization of Co3(SeO3)(SeO4)(OH)2 measured at 2.4 K exhibits a 1/3-magnetization plateau between 7.8 and 19.9 T. TheH-Tmagnetic phase diagram constructed for Co3(SeO3)(SeO4)(OH)2from ac and dc magnetic susceptibility, specific heat and magnetization measurements contains three magnetic phases I, II and III. Phase I is antiferromagnetic, while phases II and III are ferrimagnetic and responsible for the 1/3-magnetization plateau. To interpret these complex magnetic properties, we identified the correct spin lattice for Co3(SeO3)(SeO4)(OH)2 by evaluating its intralayer and interlayer spin exchanges based on spin-polarized DFT+U calculations.

Hierarchical subcomponent self-assembly of covalent triple-stranded complexes with 3d-4f vertices: luminescence and magnetic properties.

Well-defined 3d-4f heterometallic supramolecular architectures have attracted attention because of their applications in the field of luminescence and magnetism. However, covalent metallo-supramolecular discrete complexes, decorated with hetero-metallic vertices, have never been reported because of the difficulties in design and control. Herein, we report a series of covalent metallo-supramolecular discrete complexes with 3d-4f vertices synthesized by hierarchical subcomponent self-assembly of tris(2-aminoethyl)amine, 2,6-diformyl-p-cresol, and lanthanide ions (Ln) with different amines and transition metal ions. The programmable self-assembly process results in the formation of triple-stranded hetero-metallic covalent organic discrete complexes, namely 3a-3c-(Ln, Zn) (Ln = SmIII, EuIII, DyIII, YbIII and LuIII) and 3a'-(Dy, Co), which are characterized by nuclear magnetic resonance (NMR) analysis, electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS), and single-crystal X-ray analysis. Photophysical investigations disclose that the organic skeleton of 3a-(Ln, Zn) exhibits an excellent sensitizing ability toward SmIII, EuIII, and YbIII ions, displaying characteristic luminescence emission in both the visible and near-infrared (NIR) regions. AC susceptibility measurements of 3a'-(Dy, Co) reveal the frequency-independent performance under zero dc field, suggesting the absence of slow relaxation of magnetization. This work offers a new approach for the fabrication of discrete metallic covalent architectures with 3d-4f vertices.

Kink distortion of the pseudo-S4 axis in pseudotetrahedral [N2O2] bis-chelate cobalt(II) single-ion magnets leads to increased magnetic anisotropy.

Two new mononuclear cobalt(II) complexes with the general formula [Co(L1,2)2] (1 and 2) were synthesized using bidentate Schiff base ligands with NO donor set, namely, 2-(benzothiazole-2-ylimino)methyl-5-(diethylamino)phenol (HL1) and its methyl substituted derivative 2-(6-methylbenzothiazole-2-ylimino)methyl-5-(diethylamino)phenol (HL2). X-ray structure analysis reveals a distorted pseudotetrahedral coordination sphere at the cobalt(II) ion, that cannot be described by a simple twisting of the two ligand chelate planes with respect to each other, which would imply a rotation about the pseudo-S4 axis of the complex. Such a pseudo-rotation axis would approximately be colinear with the two vectors defined by the cobalt ion and the two centroids of the chelate ligands, where the angle κ between the two vectors would be 180° in an ideal pseudotetrahedral arrangement. For complexes 1 and 2, the observed distortion can be characterized by a significant bending at the cobalt ion with angles κ of 163.2° and 167.4°, respectively. Magnetic susceptibility and FD-FT THz-EPR measurements together with ab initio calculations reveal an easy-axis type of anisotropy for both complexes 1 and 2, with a spin-reversal barrier of 58.9 and 60.5 cm-1, respectively. For both compounds, frequency-dependent ac susceptibility measurements show an out-of-phase susceptibility under applied static fields of 40 and 100 mT, which can be analyzed in terms of Orbach and Raman processes within the observed temperature range.

Double dicyanamide decorated double phenoxide bridged MnIII dimer with single-molecule magnetic behaviour and bio-catalytic activity

Herein, we report the magnetic properties and bio-catalytic activity of a flying bee-like double phenoxido bridged dinuclear MnIII-Schiff base complex decorated with double dicyanamide (dca−) ligands and formulated as: [Mn2(L)2(dca)2] (1) (where H2L = 2,2′-((1E,1′E)-(ethane-1,2-diylbis(azanylylidene))-bis(ethan-1-yl-ylidene))diphenol). The complex has been synthesised by one-pot stepwise reaction of the tetradentate Schiff’s base ligand H2L with MnCl2 and dca− at 1:1:2 ratio under aerobic conditions. It has been characterized by single crystal X-ray diffraction (SC-XRD) and spectroscopic techniques. Complex 1 contains two MnIII ions connected by a double phenoxido bridge in an octahedral geometry and terminal dca− ligands. The dimers are connected to other dimers through both hydrogen bonding and π-interactions to form an extended supramolecular network. The present study reveals that in presence of tetradentate Schiff base ligands, the use of a 1:2 Mn:dca− ratio leads to formation of a dimeric MnIII complex in contrast to the discrete mononuclear complexes or 1D structures previously obtained for the Mn:dca− ratio of 1:1. The magnetic study indicates that the dimeric MnIII complex shows a negligible MnIII–MnIII interaction and a large anisotropy. The AC susceptibility measurements indicate that complex 1 behaves as a field-induced single-molecule magnet (SMM), with a high energy barrier of 73(4)K. The study of model catechol oxidase-like enzyme activity of complex 1 indicates that the dimeric MnIII complex acts as an active catalyst (kcat = 34.94 h−1) in the oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) in presence of aerial O2 in acetonitrile medium.

Anomalous electromagnetic response in the spin-triplet superconductor UTe2

The recently discovered heavy-fermion superconductor ${\mathrm{UTe}}_{2}$, as a promising candidate for an odd-parity superconductivity, exhibits anomalous magnetic-field reinforced superconductivity with a huge upper critical field of 35 T. However, the thermodynamic properties of this unconventional superconductivity still remain unclear. Herein we present the results of dc magnetization and heat capacity measurements in ${\mathrm{UTe}}_{2}$ to probe the magnetic response at low temperatures. The obtained isothermal magnetization in the superconducting state of ${\mathrm{UTe}}_{2}$ clearly demonstrates the anomalous magnetic flux pinning effect, which is most likely related to the peculiar electromagnetic response of the spin-triplet pairing state in the hard-magnetization axis (orthorhombic $b$ axis). The ac susceptibility measurements support the anomalous vortex states in ${\mathrm{UTe}}_{2}$. We also found evidence for the Lifshitz transition just above ${H}_{\mathrm{c}2}$ and the anomalous flux pinning anomalies for the easy-magnetization axis ($a$ axis).

Probing the Magnetization Relaxation Dynamics of Four-Coordinate Lanthanide(III) Complexes

The reaction of bulky trimethylsilylanilide (N-TMSA) ligand with various lanthanide salts led us to isolate unusual and unique four-coordinate monomeric Ln(III) complexes which are challenging to isolate and not surprisingly rare in the literature. The single crystal X-ray diffraction unveils that all the complexes are monomeric and isostructural with the general molecular formula of [Ln(N-TMSA)3(THF)] where Ln = Dy (1) or Yb (2). Both complexes are found to possess distorted tetrahedral geometry. For all the complexes, detailed dc and ac susceptibility measurements were performed and both 1 and 2 show frequency-dependent out-of-phase susceptibility signals only in the presence of an optimum external magnetic field. The experimental observations are well supported by theoretical calculations and developed magneto-structural correlation using the various model complexes.

Evidence of Griffith phase in quantum critical region of Dy2Ti1.8Mn0.2O7

We herein present the spin freezing dynamics of doped polycrystalline compound Dy2Ti1.8Mn0.2O7 using ac and dc magnetic measurements. A new relaxation peak (T*) appears in ac susceptibility measurement with the fractional inclusion of Mn at the Ti site in Dy2Ti2O7, indicating the presence of a short-range magnetically ordered state in the paramagnetic state. The evidence of the ‘Griffiths phase’-like state has been observed in the quantum critical region of Dy2Ti1.8Mn0.2O7. Arrhenius fit of freezing temperature (T*) with frequency for Dy2Ti1.8Mn0.2O7 shows that the spin relaxation at T* is thermally induced. Low-temperature structural change in lattice parameters and crystal field phonon coupling has been studied using synchrotron X-ray diffraction. Debye-Grüneisen's temperature-dependent lattice-volume analysis shows the ‘crystal field’-phonon coupling emergence at a much higher temperature (70 K) in Dy2Ti1.8Mn0.2O7 in contrast to 30 K in Dy2Ti2O7. These findings make Dy2Ti1.8Mn0.2O7 a suitable system to explore the application of the spin ice phenomenon at a workable temperature.

Octanuclear Ln(III)-Based Clusters Assembled by a Polydentate Schiff Base Ligand and a β-Diketone Co-Ligand: Efficient Conversion of CO2 to Cyclic Carbonates and Large Magnetocaloric Effect

A series of new Ln8 clusters [Ln8(acac)4(HL)4(L)2(μ3-O)4(C2H5O)4]·2C2H5OH·2CH2Cl2 (Ln(III) = Gd (1), Dy (2), and Ho (3); Hacac = acetylacetone and H2L = 2-hydroxy-benzoic acid (5-hydroxymethyl-furan-2-ylmethylene)-hydrazide) have been designed and constructed using a multiple coordination site Schiff base ligand (H2L) as well as a β-diketonate auxiliary ligand. The structures, magnetic properties, and catalytic performance of clusters 1–3 have been studied. X-ray crystallography data revealed that clusters 1–3 possess similar structures with two chair-form Ln4 cores bridged by four μ3-O atoms. Clusters 1–3 display extensive and high solvent stability. Magnetic analysis exhibits that cluster 1 possesses a comparably large magnetocaloric effect (−ΔSm = 33.06 J kg–1 K–1 at 2.0 K and 7.0 T). AC susceptibility measurement suggests that cluster 2 exhibits single-molecule magnet behavior under zero-field conditions. What’s more, all clusters can effectively convert CO2 with epoxides. The highest yield is 98% at 70 °C 0.1 MPa catalyzed by 1. In addition, cluster 1 can be reused three times with a negligible loss of catalytic activity.

New insights into the crystal structure of UTE0.25Ge2 = U4TGe8 (TE = Ru, Os) and ferromagnetic properties of the Os-bearing uranium germanide

A single crystal of the compound previously described as “URu0.25Ge2” was studied by means of transmission electron microscopy and synchrotron X-ray diffraction (XRD) measurements. The experiments revealed that the deficient ruthenium atoms order to a superstructure of the CeNiSi2 structure-type with space group P21/n (no. 14) and cell parameters a’ ​= ​5.7422(7) Å, b’ ​= ​15.931(2) Å, c’ ​= ​11.4903(9) Å and β’ ​= ​90.755(8)°, corresponding to the Tb4FeGe8-type structure. In addition, a new isostructural compound, U4OsGe8, was synthesized and characterized by powder X-ray diffraction, electron diffraction, DC magnetization, AC susceptibility, electrical resistivity and specific heat measurements. The experiments showed that it crystallizes with the monoclinic, ordered P21/n unit cell with lattice parameters a’ ​= ​5.7438(1) Å, b’ ​= ​15.9355(1) Å, c’ ​= ​11.4586(1) Å and β’ ​= ​90.681(1)°, and orders ferromagnetically at about 54 ​K, which is clearly seen in all the physical properties studied. Moreover, its electrical resistivity was found to exhibit features characteristic of semimetals, and the electron contribution to the specific heat is moderately enhanced, as in all other known phases of the UTE1-xGe2 (with TE ​= ​transition element) family of compounds.