Dc Field Research Articles

Design of Heterometallic {LnIII–MV} (Ln = Dy, Er; M = W, Mo) Molecular Nanomagnets: Protonation Induced Structural Diversification

The construction of lanthanide-based molecular magnets by a self-assembly strategy of multidentate building blocks and functional ligands is continuing to be a hot research topic. Among them, embedding 4d/5d-based building blocks into 4f molecular nanomagnets is promising as it can bring about more fascinating structures and stronger interactions between 4d/5d and 4f ions. In this work, we report the self-assembly reaction of trivalent lanthanide ions (DyIII, ErIII), multidentate ligand 1,3-di(2-pyridinyl)-1,3-propanedione (HL), and octacyanometallate building blocks [MV(CN)8]3– (M = W, Mo). Three different types of cyano-bridged complexes: (i) one-dimensional (1-D) chains {[Dy2[W(CN)8](L)3(H2O)3(CH3OH)]·6CH3OH·4H2O}n (1DyW) and {[Dy2[Mo(CN)8](L)3(H2O)4]·15H2O}n (2DyMo); (ii) tetranuclear clusters {[Dy[Mo(CN)8](HL)2(H2O)2]}2·14H2O (3DyMo) and {[Er[Mo(CN)8](HL)2(H2O)2]}2·14H2O (6ErMo); (iii) a trinuclear cluster {[Er2[W(CN)8](L)3(H2O)4]}·4CH3OH·4H2O (4ErW); and one bimetallic cation–anionic pair {[Er(HL)2(H2O)4]·[Mo(CN)8]}·7H2O (5ErMo) were obtained. Single-crystal X-ray diffraction analyses show that 1DyW and 2DyMo crystallize in the monoclinic space group and form neutral cyano-bridged chains; 3DyMo and 6ErMo are isostructural complexes that form a rare example of square-type d–f complexes; 4ErW is a discrete trinuclear complex, and 5ErMo consists of a {Er(HL)2(H2O)4}3+ cation and a [Mo(CN)8]3– anionic moiety. Interestingly, one of the two pyridyl groups in β-diketone ligands is protonated during the formation of 3DyMo, 5ErMo, and 6ErMo, which is uncommon in related complexes. Magnetic analyses reveal that 1DyW, 2DyMo, 5ErMo, and 6ErMo show field-induced single-molecule magnet (SMM) behaviors, and 3DyMo is a typical SMM with an energy barrier of 119.6 K under zero dc field. Ab initio calculations were performed on these series of {LnIII–MV} heteronuclear complexes in order to provide more insights into the magnetic exchange interactions between 4d and 4f centers and their influences on the magnetic relaxation properties.

MII(H2dapsc)]-[Cr(CN)6] (M = Mn, Co) Chain and Trimer Complexes: Synthesis, Crystal Structure, Non-Covalent Interactions and Magnetic Properties.

Four new heterometallic complexes combining [MII(H2dapsc)]2+ cations with the chelating H2dapsc {2,6-diacetylpyridine-bis(semicarbazone)} Schiff base ligand and [Cr(CN)6]3- anion were synthesized: {[MII(H2dapsc)]CrIII(CN)6K(H2O)2.5(EtOH)0.5}n·1.2n(H2O), M = Mn (1) and Co (2), {[Mn(H2dapsc)]2Cr(CN)6(H2O)2}Cl·H2O (3) and {[Co(H2dapsc)]2Cr(CN)6(H2O)2}Cl·2EtOH·3H2O (4). In all the compounds, M(II) centers are seven-coordinated by N3O2 atoms of H2dapsc in the equatorial plane and N or O atoms of two apical -CN/water ligands. Crystals 1 and 2 are isostructural and contain infinite negatively charged chains of alternating [MII(H2dapsc)]2+ and [CrIII(CN)6]3- units linked by CN-bridges. Compounds 3 and 4 consist of centrosymmetric positively charged trimers in which two [MII(H2dapsc)]2+ cations are bound through one [CrIII(CN)6]3- anion. All structures are regulated by π-stacking of coplanar H2dapsc moieties as well as by an extensive net of hydrogen bonding. Adjacent chains in 1 and 2 interact also by coordination bonds via a pair of K+ ions. The compounds containing MnII (1, 3) and CoII (2, 4) show a significant difference in magnetic properties. The ac magnetic measurements revealed that complexes 1 and 3 behave as a spin glass and a field-induced single-molecule magnet, respectively, while 2 and 4 do not exhibit slow magnetic relaxation in zero and non-zero dc fields. The relationship between magnetic properties and non-covalent interactions in the structures 1-4 was traced.

Electrical Tree Initiation and Growth in LDPE Under Negative HVDC Superimposed With AC Ripples

Understanding the role of power quality in the aging of HVdc cable systems is critical to the reliable connection of offshore renewable energy sources, and hence global ambitions to reduce carbon emissions. This work investigates electrical treeing with a needle-plane geometry in low-density polyethylene (LDPE) under a high negative dc voltage superimposed with ac ripples (−60 kV dc ± 7 kV ac). Tree initiation showed behavior similar to that widely reported under pure power frequencies. Subsequent tree growth, however, was observed to be confined in a smaller area with limited length and width than seen under pure ac voltages, even after long periods of voltage application. Traditional 2-D imaging showed overlapped tree channels which developed to cover the whole area within the tree outline. A distinguishing tree shape resulted, which we have named a “slim bouquet” shape. The volume rendering from X-ray computed tomography (XCT) showed the structure had a 3-D fractal dimension greater than 2, considerably larger than its 2-D representation. PD signals during the growth had wing-like phase-resolved partial discharge (PRPD) clusters and signal phase concentrations between 10°–45° appeared after hours of growth. There was a comb-like appearance in maximum partial discharge (PD) magnitude variation, which is typical in pure high negative dc fields. Consideration is given to both space charge distribution controlled by high dc fields and continuous degradation by ac fields to explain the slim bouquet tree formation.

Effects of DC Polarity and Field Uniformity on Breakdown of SF₆ and C₃F₇CN/CO₂ Mixture

To address the issues of greenhouse gases and resultant global warming, there is an urgency to find an electronegative gas to replace SF6 in global power system networks. This article provides an experimental study of various factors on DC breakdown of electronegative gases. Rod-plane geometries with a range of rod diameters (3.5–12.5 mm) and electrode separations (5–55 mm) are used to provide different degrees of field uniformity. SF6 and a 20% C3F7CN / 80% CO2 mixture are tested under pressures ranging between 1 and 5 bar. Breakdown voltages (BDVs) under both polarities rise linearly with gap distance in quasi-uniform fields with the positive being higher. Increasingly nonuniform fields lead to saturation in the case of positive BDV, while in the negative polarity case, the BDV increases linearly. As a result, the two polarities’ BDV magnitudes crossover as field nonuniformity increases. The value at which the negative value exceeds the positive is dependent on the field uniformity, pressure, and gas medium. A simulation based on the streamer criterion model provides a good agreement with experimental results for positive DC breakdown in the range of 2–5 bar. In terms of the insulation characteristics, 20% C3F7CN / 80% CO2 could provide a valuable alternative to SF6 in high-voltage plant for outdoor applications in hot-climate countries and indoor applications in cold-climate countries.

Orientation control of the hexagonal and lamellar phases in thin block copolymer films using in-plane AC electric field

Lamellar and hexagonal pattern rearrangements in thin films of polystyrene–block–poly(2-vinyl pyridine) and polystyrene–block–poly(4-vinyl pyridine) copolymers simultaneously exposed to an in-plane AC electric field and saturated chloroform vapor are studied with atomic force microscopy and analyzed via the numerical solution of the self-consistent field theory equations. It is demonstrated that the use of AC field with the root-mean-square strength higher than 8 V⋅μm−1 allows one to effectively orient microphase-separated domains along the field direction on the tens of microns scale. At the same time, the AC field considerably lowers the risk of breakdown and eliminates effects related to ionic transport in the presence of solvent vapor. The role of such factors as the exposure time, field strength and frequency is investigated. Theoretical considerations prove the equivalent effect of AC and DC fields on the structure of the copolymer film in a wide frequency range. Self-consistent field theory calculations of the free energy as a function of film thickness make it possible to exactly identify which phase dominates in the film. In particular, an apparent transformation of standing cylinders into long threads aligned in the field direction should be interpreted as the phase transition from the perpendicular to parallel hexagonal phase, which can take place in a certain range of film thicknesses, provided the electric field strength exceeds a certain threshold value. In the case of a perpendicular lamellar phase, the domain orientation along the direction of the electric field is always profitable. The observed morphological rearrangements under an in-plane field, which preserve connectivity between the film surfaces through the domains of the minor copolymer block, can be important for practical applications.

Electric field-induced phase transition from the glasslike to paraelectric phase and dielectric spectra hardening in PMN single crystal

One of the key points in the physics of the relaxors is their response to the applied DC field. Many studies of this topic were made, in particular on the influence of the field on the dielectric properties. However, practically, in all the cases, the measurements were performed at a fixed frequency and usually with the change in the temperature at the fixed field strength. In this paper, we report the evolution of the dielectric spectra at low frequencies (0.1 Hz [Formula: see text] 1 kHz) at fixed temperature 246 K on changing the DC electric field applied in (111) from 1 kV to 7 kV. Cole-Cole function was used to describe the spectra and the field dependences of the mean relaxation time [Formula: see text], the oscillation strength [Formula: see text] and the width parameter [Formula: see text] were determined. The obtained [Formula: see text]([Formula: see text]) and [Formula: see text] [Formula: see text]([Formula: see text]) provide evidence of the field-induced transition from the nonpolar glass-like phase to the nonpolar paraelectric phase at around 1.5 kV/cm. In the paraelectric phase, very fast hardening of the spectra was observed with [Formula: see text] changing from 10 s to about [Formula: see text]s. The performed analysis demonstrated that the earlier reported positive C-V effect is completely determined by the spectra hardening, while [Formula: see text][Formula: see text] does not show any change in the glass-like phase and monotonously decreases with a field increase in the paraelectric state. For complete understanding of the microscopic origin of the observed phenomena, a detailed study on the short-and long-range structures at the same condition is necessary.

Domain structure evolution during polarization reversal in calcium orthovanadate single crystals

We have switched polarization in calcium orthovanadate single crystal with as-grown domain structure consisting of isolated domains with charged domain walls (CDWs) located in the bulk using pretreatment by ac field and subsequent switching in dc field at the elevated temperature. The formation of the domain ledges at the CDW in the bulk and their growth in the polar direction has been revealed. The isolated domains with optically well-defined walls appeared when the ledge tops reached the surface, their shape and sizes remaining constant during further switching. Unlike usual continuous domain wall motion, we have observed the discrete switching by arising of the isolated domains without any input of the traditional domain nucleation at the polar surface. The obtained results have been explained under the assumption that at the used experimental conditions, the applied field is above the threshold value for ledge nucleation at CDW in the bulk, but below the threshold for domain wall motion at the surface. Thus, we have obtained the discrete switching by ledge growth without any sideways motion of the domain walls and domain coalescence. The nonuniform evolution of the domain structure at the surface is due to the dependence of the switching rate on the distance from CDW to the polar surface, which is random in the studied domain structure.

Pinning potential in highly performant CaKFe4As4 superconductor from DC magnetic relaxation and AC multi-frequency susceptibility studies

We have investigated the pinning potential of high-quality single crystals of superconducting material CaKFe4As4 having high critical current density and very high upper critical field using both magnetization relaxation measurements and frequency-dependent AC susceptibility. Preliminary studies of the superconducting transition and of the isothermal magnetization loops confirmed the high quality of the samples, while temperature dependence of the AC susceptibility in high magnetic fields show absolutely no dependence on the cooling conditions, hence, no magnetic history. From magnetization relaxation measurements were extracted the values of the normalized pinning potential U*, which reveals a clear crossover between elastic creep and plastic creep. The extremely high values of U*, up to 1200 K around the temperature of 20 K lead to a nearly zero value of the probability of thermally-activated flux jumps at temperatures of interest for high-field applications. The values of the creep exponents in the two creep regimes resulted from the analysis of the magnetization relaxation data are in complete agreement with theoretical models. Pinning potentials were also estimated, near the critical temperature, from AC susceptibility measurements, their values being close to those resulted (at the same temperature and DC field) from the magnetization relaxation data.

Dc Quantum Magnetometry below the Ramsey Limit

We demonstrate quantum sensing of dc magnetic fields that exceeds the sensitivity of conventional $T_2^\ast$-limited dc magnetometry by more than an order of magnitude. We used nitrogen-vacancy centers in a diamond rotating at periods comparable to the spin coherence time, and characterize the dependence of magnetic sensitivity on measurement time and rotation speed. Our method up-converts only the dc field of interest and preserves the quantum coherence of the sensor. These results definitively improve the sensitivity of a quantum magnetometer to dc fields, an important and useful addition to the quantum sensing toolbox.

Utilization of diamagnetic Zn(II) ion to boost the anisotropic nature of Ln(III) ion in heterodinuclear Zn(II)–Ln(III) single‐molecule magnets

A series of dimetallic ZnII–LnIII compounds of general formulae [LnZn(L)3(NO3)2]·2CH3OH (LnIII = DyIII (1), TbIII (2), GdIII(3)) was prepared by stepwise reaction of compartmental ligand LH = ((E)‐2‐((pyridin‐2‐ylmethylene)amino)phenol) with Ln (NO3)3·xH2O and Zn (NO3)2·xH2O in the presence of triethylamine as base. The single crystal XRD analysis indicated that both metallic ions are connected to each other through phenolic oxygen atom from fully deprotonated ligand. Based on the SHAPE analysis, the DyIII ion has nine coordination numbers with distorted spherical capped square antiprism geometry, while the ZnII ion has six coordination numbers with distorted octahedral geometry. DC magnetic studies reveal the existence of antiferromagnetic interaction between the ZnII and LnIII metal centers. AC magnetic studies reveal that the complex 1 show field‐induced single‐molecule magnet (SMM) properties with an effective energy barrier of 155 K under an applied dc field of 0.1 T, whereas complex 2 does not show SMM behavior. Furthermore, we conducted DFT and ab initio CASSCF + RASSI‐SO calculations to probe the single‐ion properties of Ln(III) ions and to understand the role of the diamagnetic ZnII ion in the magnetization relaxation in order to interpret the experimental observations. Ab initio calculations predict that the gz values are strongly axial in nature in the ground state of Dy(III) ion in complex 1 and that allows the magnetic relaxation to occur via excited states with a Ucal of 380.8 K. DFT calculations discovered that the presence of the diamagnetic Zn(II) ion causes greater negative charges on the bridging oxygen atoms, which enhances the anisotropy of Dy(III) ion and thus reduces the quantum tunneling of magnetization (QTM) effects, and helps to achieve better SMM features for 1.

Manipulating the non-Hermitian skin effect via electric fields

In non-Hermitian systems, the phenomenon that the bulk-band eigenstates are accumulated at the boundaries of the systems under open boundary conditions is called non-Hermitian skin effect (NHSE), which is one of the most iconic and important features of a non-Hermitian system. In this work, we investigate the fate of NHSE in the presence of electric fields by analytically calculating the dynamical evolution of an initial bulk state and numerically computing the spectral winding number, the distributions of eigenstates, as well as the dynamical evolutions. We show abundant manipulation effects of dc and ac fields on the NHSE, and that the physical mechanism behind these effects is the interplay between the Stark localization, dynamic localization and the NHSE. In addition, the finite size analysis of the non-Hermitian system with a pure dc field shows the phenomenon of size-dependent NHSE. We further propose a scheme to realize the discussed model based on an electronic circuit. The results will help to deepen the understanding of NHSE and its manipulation.

Soft magnetic composite core properties in normalized representation

In this work a theoretical investigation will be presented on the DC field dependence of magnetic induction (B(H)) and of effective permeability (µeff(H)) of the soft magnetic composites samples. Two characteristic fields have been deduced for a set of powder cores: the anisotropy field, HK, applying the Barandiaran method and the curvature parameter, c, applying a fitting procedure. These two parameters are strongly correlated. The field dependencies of magnetizations and of effective permeability’s collapse in a common curve applying the anisotropy field as a normalizing parameter. Such a normalized representation can help the check of consistency of the technology for production of powder cores. Effective magnetic induction saturation was introduced as an average product of the anisotropy field and effective permeability which can be used as a figure of merit parameter comparing to the saturation magnetic induction of the material of the powder cores.

Effect of external DC field on current transformers with amorphous and nanocrystalline cores

Nanocrystalline and amorphous stress-annealed and field annealed tapes are used for cores of DC-tolerant current transformers. We analyze the influence of external DC field of arbitrary direction on the performance of these transformers. For the realistic core shapes the demagnetization is high, which leads to effective external field suppression. However, DC tolerant transformers are tolerant to the DC component of the current and not to the external field - they can be saturated by 30 mT field from permanent magnet. This means that for the practical applications in domestic energy meters some external shielding is required.

Static Negative-Permeability Metasurface to Transfer Volumetric Static Magnetic Field

Inspired by transformation optics, negative permeability materials enable the transfer of static magnetic fields to a distant location far away from the current source. This is useful for situations in which it is difficult to place a current source near the region where magnetic fields are required. However, existing artificial negative permeability materials are three dimensional (3D) and bulky. In this study, we theoretically design and experimentally demonstrate a metasurface with static negative permeability that displaces volumetric 3D magnetic fields to a distant region. The design overcomes the existing limitation because the dimensions of the structure are reduced to two, and the control of the magnetic field has an increased degree of freedom. The proposed method can be further extended to tools and strategies to precisely displace and/or manipulate dc or quasistatic magnetic fields in regions of interest for various applications such as medical care and measurement precision.

High-accuracy determination of Paul-trap stability parameters for electric-quadrupole-shift prediction

The motion of an ion in a radiofrequency (rf) Paul trap is described by the Mathieu equation and the associated stability parameters that are proportional to the rf and dc electric field gradients. Here, a higher-order, iterative method to accurately solve the stability parameters from measured secular frequencies is presented. It is then used to characterize an endcap trap by showing that the trap’s radial asymmetry is dominated by the dc field gradients and by measuring the relation between the applied voltages and the gradients. The results are shown to be in good agreement with an electrostatic finite-element-method simulation of the trap. Furthermore, a method to determine the direction of the radial trap axes using a “tickler” voltage is presented, and the temperature dependence of the rf voltage is discussed. As an application for optical ion clocks, the method is used to predict and minimize the electric quadrupole shift (EQS) using the applied dc voltages. Finally, a lower limit of 1070 for the cancellation factor of the Zeeman-averaging EQS cancellation method is determined in an interleaved low-/high-EQS clock measurement. This reduces the EQS uncertainty of our 88Sr+ optical clock to ≲1×10−19 in fractional frequency units.

New wheel-shaped Ln6 clusters for conversion of CO2 and magnetic properties

A series of novel hexanuclear lanthanide clusters, namely, [Ln6(HL)6(NO3)6]·3CH3CN (Ln = Gd(1), Tb(2), Dy(3) and Er(4)) was assembled using a multidentate ligand H3L (trolamine). The clusters 1–4 show a wheel-shaped Ln6 topology with the approximate diameter and thickness of 1.5 and 0.7 nm, respectively. All of them show high thermal stability. In the aspect of the catalytic capacities for the cycloaddition reactions of CO2 and epoxide, the reaction conditions, the substrate scope, and possible catalytic mechanism were investigated. The highest yield for clusters 1–4 is up to 99% at 333 K for 12 h. In particular, cluster 1 can be reused at least three times with no obvious loss of catalytic performance and keep the integrity of the crystal structure. Magnetic investigations reveal that cluster 1 exhibits a relatively large magnetocaloric effect with −ΔSm = 41.43 J/(kg⋅K) (T = 3.0 K, 7.0 T); while cluster 3 displays slow magnetic relaxation behavior under zero dc field with Ueff = 0.51 K and τ0 = 2.54 × 10−5 s.

Modeling of core-shell magneto-electric nanoparticles for biomedical applications: Effect of composition, dimension, and magnetic field features on magnetoelectric response.

The recent development of core-shell nanoparticles which combine strain coupled magnetostrictive and piezoelectric phases, has attracted a lot of attention due to their ability to yield strong magnetoelectric effect even at room temperature, thus making them a promising tool to enable biomedical applications. To fully exploit their potentialities and to adapt their use to in vivo applications, this study analyzes, through a numerical approach, their magnetoelectric behavior, shortly quantified by the magnetoelectric coupling coefficient (αME), thus providing an important milestone for the characterization of the magnetoelectric effect at the nanoscale. In view of recent evidence showing that αME is strongly affected by both the applied magnetic field DC bias and AC frequency, this study implements a nonlinear model, based on magnetic hysteresis, to describe the responses of two different core-shell nanoparticles to various magnetic field excitation stimuli. The proposed model is also used to evaluate to which extent realistic variables such as core diameter and shell thickness affect the electric output. Results prove that αME of 80 nm cobalt ferrite-barium titanate (CFO-BTO) nanoparticles with a 60:40 ratio is equal to about 0.28 V/cm∙Oe corresponding to electric fields up to about 1000 V/cm when a strong DC bias is applied. However, the same electric output can be obtained even in absence of DC field with very low AC fields, by exploiting the hysteretic characteristics of the same composites. The analysis of core and shell dimension is as such to indicate that, to maximize αME, larger core diameter and thinner shell nanoparticles should be preferred. These results, taken together, suggest that it is possible to tune magnetoelectric nanoparticles electric responses by controlling their composition and their size, thus opening the opportunity to adapt their structure on the specific application to pursue.

Simultaneous nitrification and denitrification by controlling current density and dissolved oxygen supply in a novel electrically-induced membrane bioreactor

In this work, a simultaneous nitrification and denitrification (SND) process in a novel electrically-induced membrane bioreactor (eMBR) was established to treat nitrogen (N) and carbon wastewater. The impact of applied current density (CD) on the important operational parameters of the eMBR was also explored. Furthermore, the performance of denitrification and N-removal at various applied CDs (0–23 A/m2) were investigated. Results showed that high biological oxidation of NH4+−N and total nitrogen (TN) removals were attained at an intermittent CD of 12.5 A/m2 with a low aeration (<2.5 mg/L DO) provided by the eMBR system. The maximum NH4+−N and TN removal efficiencies of the eMBR were 98.71% and 83.75%, respectively. The average denitrification rate was enhanced by the adequate application of DC fields to the eMBR with an increase of NO3−−N removal efficiency from 8.3% to 90.5% and SND rate from 40.3% to 96.28%. It is possible that autotrophic and heterotrophic denitrification together contributed to the high performance of the eMBR process and the complete removal of the nitrate, thereby achieving average TN effluent concentrations of <5 mg/L. The eMBR also reached constant and substantial chemical oxygen demand (COD) removal efficiencies of 99.45%. Taken together, such technology presented in this work could potentially decrease energy demands and could lead to the further development of an energy self-sustained N-removal process. The eMBR could be used in a new WWTP design or for retrofitting existing treatment plants.

Series of Benzoquinone-Bridged Dicobalt(II) Single-Molecule Magnets.

Mononuclear complexes within a particular coordination geometry have been well recognized for high-performance single-molecule magnets (SMMs), while the incorporation of such well-defined geometric ions into multinuclear complexes remains less explored. Using the rigid 2-(di(1H-pyrazol-1-yl)methyl)-6-(1H-pyrazol-1-yl)pyridine (PyPz3) ligand, here, we prepared a series of benzoquinone-bridged dicobalt(II) SMMs [{(PyPz3)Co}2(L)][PF6]2, (1, L = 2,5-dioxo-1,4-benzoquinone (dhbq2-); 2, L = chloranilate (CA2-); and 3, L = bromanilate (BA2-)), in which each Co(II) center adopts a distorted trigonal prismatic (TPR) geometry and the distortion increases with the sizes of 3,6-substituent groups (H (1) < Cl (2) < Br (3)). Accordingly, the magnetic study revealed that the axial anisotropy parameter (D) of the Co ions decreased from -78.5 to -56.5 cm-1 in 1-3, while the rhombic one (E) increased significantly. As a result, 1 exhibited slow relaxation of magnetization under a zero dc field, while both 2 and 3 showed only the field-induced SMM behaviors, likely due to the increased rhombic anisotropy that leads to the serious quantum tunneling of the magnetization. Our study demonstrated that the relaxation dynamics and performances of a multinuclear complex are strongly dependent on the coordination geometry of the local metal ions, which may be engineered by modifying the substituent groups.

Magnetic Properties of a Solid Solution Fe1−xAgxCr2S4 (0 &lt; x &lt; 0.2)

The magnetic properties of the Fe1−xAgxCr2S4 (0 &lt; x &lt; 0.2) solid solution were investigated in the temperature range 4–300 K in a DC field of 0.1 and 45 kOe. Fe1−xAgxCr2S4 is characterized by the transition temperature from the paramagnetic to the ferromagnetic state (Tc) and the irreversibility temperature (Tirr). The replacement of iron with silver ions in Fe1−xAgxCr2S4 leads to an increase in the Curie temperatures from 185 K (x = 0) to 216 K (x = 0.2) and Tcusp from 45 K (x = 0) to 125 K (x = 0.2). A section of the Fe1−xAgxCr2S4 magnetic phase diagram in the region under study has been constructed. The diagram reveals the following regions: paramagnetic, ferromagnetic, region of conditionally recurrent spin-glass (SG), and below 10 K a region associated with orbital ordering.