Iron Telluride Research Articles

Iron telluride Fe1.1Te doped with TiS2 and NbS2: Appearance of superconducting state coexisting with antiferromagnetism

The effect of titanium or niobium disulfides doping of iron telluride has been studied for the first time by means of x-ray diffraction analysis, electrical resistivity and magnetization measurements. It has been revealed that an increase in the dopant content in the Fe1.1Te(TS2)y (T = Ti, Nb) systems (y = 0, 0.04, 0.08, 0.1, 0.2) is accompanied by the additional phase separation and leads to a decrease in the crystal lattice parameters of the tetragonal phase, partial suppression of antiferromagnetic ordering and an appearance of superconductivity. In doped samples a transition to the superconducting state has been detected upon cooling below Tconset ∼9 K coexisting with antiferromagnetism. Superconductivity is suggested to exhibit a granular character due to inhomogeneity of the samples and the small volume fraction of superconducting phase. The difference in the superconducting transitions for both dopant types may be associated with different morphologies and compositions of resulting phases.

On statistical evaluation of reverse degree based topological indices for iron telluride networks

In the context of graph theory and chemical graph theory, this research conducts a detailed mathematical investigation of reverse topological indices as they relate to iron telluride networks, clarifying their complex interactions. Graph theory is a branch of abstract mathematics that carefully studies the connections and structural features of graphs made up of edges and vertices. These theoretical ideas are expanded upon in chemical graph theory, which models molecular architectures with atoms acting as vertices and chemical bonds as edges. By extending these concepts, this work investigates the reverse topological indices in the context of Iron Telluride networks and outlines their significant effects on chemical reactivity, molecular topology and statistical modeling. By navigating intricate mathematical formalisms and algorithmic approaches, the analysis provides profound insights into the reactivity patterns and structural dynamics of Iron Telluride compounds, enhancing our knowledge of solid-state chemistry and materials science.

Topological indices and patterns in iron telluride networks

This paper explores the complex interplay between topological indices and structural patterns in networks of iron telluride (FeTe). We want to analyses and characterize the distinct topological features of (FeTe) by utilizing an extensive set of topological indices. We investigate the relationship that these indicators have with the network’s physical characteristics by employing sophisticated statistical techniques and curve fitting models. Our results show important trends that contribute to our knowledge of the architecture of the (FeTe) network and shed light on its physiochemical properties. This study advances the area of material science by providing a solid foundation for using topological indices to predict and analyses the behavior of intricate network systems. More preciously, we study the topological indices of iron telluride networks, an artificial substance widely used with unique properties due to its crystal structure. We construct a series of topological indices for iron telluride networks with exact mathematical analysis and determine their distributions and correlations using statistical methods. Our results reveal significant patterns and trends in the network structure when the number of constituent atoms increases. These results shed new light on the fundamental factors that influence material behavior, thus offering a deeper understanding of the iron telluride network and may contribute to future research and engineering of these materials.

Extendable piezo/ferroelectricity in nonstoichiometric 2D transition metal dichalcogenides

Engineering piezo/ferroelectricity in two-dimensional materials holds significant implications for advancing the manufacture of state-of-the-art multifunctional materials. The inborn nonstoichiometric propensity of two-dimensional transition metal dichalcogenides provides a spiffy ready-available solution for breaking inversion centrosymmetry, thereby conducing to circumvent size effect challenges in conventional perovskite oxide ferroelectrics. Here, we show the extendable and ubiquitous piezo/ferroelectricity within nonstoichiometric two-dimensional transition metal dichalcogenides that are predominantly centrosymmetric during standard stoichiometric cases. The emerged piezo/ferroelectric traits are aroused from the sliding of van der Waals layers and displacement of interlayer metal atoms triggered by the Frankel defects of heterogeneous interlayer native metal atom intercalation. We demonstrate two-dimensional chromium selenides nanogenerator and iron tellurides ferroelectric multilevel memristors as two representative applications. This innovative approach to engineering piezo/ferroelectricity in ultrathin transition metal dichalcogenides may provide a potential avenue to consolidate piezo/ferroelectricity with featured two-dimensional materials to fabricate multifunctional materials and distinguished multiferroic.

Effect of Titanium Diselenide Doping on the Magnetic State and Transport Properties of FeTe

Abstract—The iron–tellurium-based compounds Fe1.1Te(TiSe2)y doped with titanium diselenide (y = 0, 0.04, 0.08, 0.1, 0.2) have been synthesized for the first time and studied by means of x-ray diffraction, electrical resistivity and magnetization measurements. It has been shown that the addition of a small amount of titanium diselenide to single-phase iron telluride with a tetragonal crystal structure leads to the appearance of superconductivity, a decrease in the Néel temperature and contraction of the crystal lattice at y ≥ 0.04. The maximal temperature of the onset of the superconducting transition \(T_{{\text{c}}}^{{{\text{onset}}}}\) ~ 13 K is observed for a sample with the nominal composition Fe1.1Te(TiSe2)0.1. The behavior of the resistivity with temperature below Tconset is observed to depend on the current value, which may indicate superconductivity characteristic of granular superconductors.

Reversible Amorphous-Crystalline Phase Transformation in an Ultrathin van der Waals FeTe System.

Searching for new phase-change materials for memory and neuromorphic device applications and further understanding the phase transformation mechanism are attracting wide attention. Phase transformation from the amorphous phase to the crystal phase has been unraveled in iron telluride (FeTe) bulk film deposited by pulsed laser deposition, recently. However, the van der Waals-layered feature of FeTe in the crystal form was not noted, which will benefit the scaling of the memory devices and shine light on phase-change heterostructures or interfacial phase-change materials. Moreover, the demonstration of advanced memory or neuromorphic device applications is lacking. Here, we investigate the phase transformation of FeTe starting from mechanically exfoliated van der Waals layers from a bulk single crystal. Surficial amorphization is revealed at the surface layers of FeTe flakes after exfoliation under ambient conditions, which could be transformed back to the crystalline phase with laser irradiation or heating. The conductance drop of the flake devices near 400 K verifies the phase transformation electrically. Memristor behavior of the amorphous surface in FeTe has been further demonstrated, proving the reversibility of the phase transformation and shining light on the possible applications of neuromorphic devices.

Heterointerface of vanadium telluride and zinc iron telluride nanosheets for highly efficient hydrogen production via water and urea electrolysis

Interface design is a promising strategy for electrocatalysis to optimize charge transfer ability and active sites of a catalyst. Herein, interfacially coupled vanadium telluride and zinc iron telluride nanosheets are synthesized on nickel foam (VTe2@ZnFeTe/NF) by a facile hydrothermal method, which furnishes low overpotentials of 119/217 mV for the hydrogen evolution reaction (HER) and 240/300 mV for the oxygen evolution reaction (OER) at 20/50 mA cm−2 in potassium hydroxide. The alkaline and urea electrolyzer formed by VTe2@ZnFeTe/NF requires an operating voltage of 1.58 V and 1.46 V to yield a current density of 10 mA cm−2 respectively. Density functional theory analysis reveals that the superb activity of VTe2@ZnFeTe/NF is related to its optimal adsorption free energy, extended electroactive centers, excellent charge transfer ability, and reasonable density of states near the Fermi level. These findings provide new insights for the design of transition metal telluride heterointerfaces as catalysts for water and urea electrolyzers.

Dependence of Transition-Metal Telluride Phases on Metal Precursor Reactivity and Mechanistic Implications.

Modern bottom-up synthesis to nanocrystalline solid-state materials often lacks the reasoned product control that molecular chemistry boasts from having over a century of research and development. In this study, six transition metals including iron, cobalt, nickel, ruthenium, palladium, and platinum were reacted with the mild reagent didodecyl ditelluride in their acetylacetonate, chloride, bromide, iodide, and triflate salts. This systematic analysis demonstrates how rationally matching the reactivity of metal salts to the telluride precursor is necessary for the successful production of metal tellurides. The trends in reactivity suggest that radical stability is the better predictor of metal salt reactivity than hard-soft acid-base theory. Of the six transition-metal tellurides, the first colloidal syntheses of iron and ruthenium tellurides (FeTe2 and RuTe2) are reported.

FeTe:Fe2TeO5 nanodots embedded MWCNTs: Nanocomposite electrode towards supercapacitor application

BackgroundFeTe:Fe2TeO5 nanodots encapsulated MWCNTs as a nanocomposite is a new hybrid electrode material tested for supercapacitor energy storage application for the first time. MethodFor the deposition of FeTe:Fe2TeO5 over MWCNTs simple, inexpensive, binder free and low-cost and thin-film method named successive ionic layer adsorption and reaction (SILAR) was used. Significant findingsFeTe:Fe2TeO5 nanodots encapsulated MWCNTs as a nanocomposite have been accomplished with the aid of sequential growth controlled chemical method. Mixed phase of iron telluride consisting of FeTe (Tetragonal) and Fe2TeO5(Monoclinic) has been well analyzed through structural studies. Due to growth of nanodots as seen through SEM images have been responsible to enhance surface area of MWCNTs/FeTe:Fe2TeO5 than that of bare FeTe:Fe2TeO5 supported by BET analysis. Oxidation states of mixed elements have been well confirmed through XPS studies. These characterization results of the electrode supporting for electrochemical supercapacitor application and hence, analyzed through electrochemical investigation inclusive of CV, GCD, EIS and electrochemical capacitance retention. Interestingly, MWCNTs/FeTe:Fe2TeO5 nanocomposite yields remarkable capacitance of 773.69 F/g at 3 mV/s, with an energy density of 8.19 Wh/kg and power density of 108 W/kg at current density of 0.8 mA/cm2. Electrodes good cyclic stability (capacitive retention) of 95% at 5000 CV cycles explores its candidature for future energy storage applications.

Mixed phase FeTe: Fe2TeO5 nanopebbles through solution chemistry: Electrochemical supercapacitor application

Mixed phase of iron telluride based thin films consisting of nanopebbles has been grown successfully over conducting stainless steel (SS) substrate through successive ionic layer adsorption reaction (SILAR) process. Crystal structural and elemental states through XPS revealed clear indication of FeTe: Fe 2 TeO 5 mixed phase growth and well supported through FTIR studies. Agglomeration of embedded quantum dots forming nanopebbles like surface architecture resulting in enhanced hydrophilic nature evident through contact angle and higher surface roughness by atomic force micrographs found beneficial as more electroactive surface area for electrolyte ions to interact. This helped to achieve a significant specific capacitance of 591 F/g (166 mF/cm 2 ) @3 mV/s potential scan rate and, 107 F/g (30 mF/cm 2 ) @0.4 mA/cm 2 in NaCl electrolyte. Performed electrochemical impedance spectroscopy (EIS) studies explored clear insight of the solution and charge transfer resistances, and relaxation time constant. Iron telluride based thin film clearly demonstrates very high value of pseudo capacitive contribution than the electric double layer due to the intrinsic pseudocapacitive behavior of mixed phase. • First report on iron telluride based (FeTe: Fe 2 TeO 5 ) thin film synthesis using simple SILAR method and successfully employed as supercapacitor electrode. • Nanopebbles embedded with quantum dots agglomeration responsible for more electrochemical active sites. • Notable specific capacitance of 591 F/g (426 C/g or 166 mF/g) at 3 mV/s by CV and 107 F/g (30 mF/cm 2 ) at 0.4 mA/cm 2 by GCD studies. • Enhanced inner (pseudo q p ) charge storage contributions than outer (EDLC q d l ).

Long life exceeding 10 000 cycles for aluminum-ion batteries based on an FeTe2@GO composite as the cathode.

A nanocomposite consisting of iron telluride wrapped with graphene oxide (GO) was prepared via a hydrothermal method. As the cathode material for aluminum-ion batteries (AIBs), it exhibited a remarkable long-term cycle performance with a reversible capacity of 120.4 mA h g-1 at 1 A g-1 after 10 000 cycles, i.e., a cyclability better than those of all other transition metal chalcogenides in AIBs reported to date. Furthermore, an energy storage mechanism, involving the intercalation and deintercalation of multiple ions (AlCl4-, Cl- and Al3+), was elucidated. This study offers guidance for further development of transition metal tellurides for AIBs.

Coupling between antiferromagnetic and spin-glass orders in the quasi-one-dimensional iron tellurideTaFe1+xTe3(x=0.25)

Understanding the interplay among different magnetic exchange interactions and its physical consequences, especially in the presence of itinerant electrons and disorders, remains one of the central themes in condensed matter physics. In this vein, the coupling between antiferromagnetic and spin glass orders may lead to large exchange bias, a property of potential broad technological applications. In this article, we report the coexistence of antiferromagnetic order and spin glass behaviors in a quasi-one-dimensional iron telluride TaFe$_{1+x}$Te$_3$ ($x$=0.25). Its antiferromagnetism is believed to arise from the antiferromagnetic interchain coupling between the ferromagnetically aligned FeTe chains along the $b$-axis, while the spin glassy state stems from the disordered Fe interstitials. This dichotomic role of chain and interstitial sublattices is responsible for the large exchange bias observed at low temperatures, with the interstitial Fe acting as the uncompensated moment and its neighboring Fe chain providing the source for its pinning. This iron-based telluride may thereby represent a new paradigm to study the large family of transition metal chalcogenides whose magnetic order or even the dimensionality can be tuned to a large extent, forming a fertile playground to manipulate or switch the spin degrees of freedom thereof.

Oxygen Adsorption Induced Superconductivity in Ultrathin FeTe Film on SrTiO3(001).

The phenomenon of oxygen incorporation-induced superconductivity in iron telluride (Fe1+yTe, with antiferromagnetic (AFM) orders) is intriguing and quite different from the case of FeSe. Until now, the microscopic origin of the induced superconductivity and the role of oxygen are far from clear. Here, by combining in situ scanning tunneling microscopy/spectroscopy (STM/STS) and X-ray photoemission spectroscopy (XPS) on oxygenated FeTe, we found physically adsorbed O2 molecules crystallized into c (2/3 × 2) structure as an oxygen overlayer at low temperature, which was vital for superconductivity. The O2 overlayer were not epitaxial on the FeTe lattice, which implied weak O2 –FeTe interaction but strong molecular interactions. The energy shift observed in the STS and XPS measurements indicated a hole doping effect from the O2 overlayer to the FeTe layer, leading to a superconducting gap of 4.5 meV opened across the Fermi level. Our direct microscopic probe clarified the role of oxygen on FeTe and emphasized the importance of charge transfer effect to induce superconductivity in iron-chalcogenide thin films.

Strain-Stabilized (π, π) Order at the Surface of Fe1+xTe.

A key property of many quantum materials is that their ground state depends sensitively on small changes of an external tuning parameter, e.g., doping, magnetic field, or pressure, creating opportunities for potential technological applications. Here, we explore tuning of the ground state of the nonsuperconducting parent compound, Fe1+xTe, of the iron chalcogenides by uniaxial strain. Iron telluride exhibits a peculiar (π, 0) antiferromagnetic order unlike the (π, π) order observed in the Fe-pnictide superconductors. The (π, 0) order is accompanied by a significant monoclinic distortion. We explore tuning of the ground state by uniaxial strain combined with low-temperature scanning tunneling microscopy. We demonstrate that, indeed under strain, the surface of Fe1.1Te undergoes a transition to a (π, π)-charge-ordered state. Comparison with transport experiments on uniaxially strained samples shows that this is a surface phase, demonstrating the opportunities afforded by 2D correlated phases stabilized near surfaces and interfaces.

Controllable synthesis and electronic structure characterization of multiple phases of iron telluride thin films

We present an investigation on the controlled growth of epitaxial iron telluride films of multiple phases by molecular beam epitaxy. By optimizing the substrate temperature, we fabricate different phases of \ensuremath{\alpha}-FeTe, \ensuremath{\beta}-FeTe, and $\mathrm{Fe}{\mathrm{Te}}_{2}$, respectively, whose crystalline morphologies are determined by means of in situ scanning tunneling microscopy/spectroscopy and ex situ scanning transmission electron microscopy. While both \ensuremath{\alpha}- and \ensuremath{\beta}-FeTe films are metallic, we uncover a \ensuremath{\sim}185- and 65-mV semiconducting band gap for the (100) and (011) facets of $\mathrm{Fe}{\mathrm{Te}}_{2}$ film, respectively, with the former one being compatible with the first principles calculations. Moreover, for $\mathrm{Fe}{\mathrm{Te}}_{2}$, we observe reduced gaps with enhanced conductance in the vicinity of edge boundaries, which are dependent on the geometries of step orientation and possibly in correlation to the magnetic anisotropy with structural distortion. Our study provides insight into the controllable synthesis of Fe-Te compounds with variation of stoichiometries and surface terminations, which may generalize to other epitaxial Fe chalcogenide films.

Conversion Reaction Mechanism for Yolk‐Shell‐Structured Iron Telluride‐C Nanospheres and Exploration of Their Electrochemical Performance as an Anode Material for Potassium‐Ion Batteries

AbstractVarious metal chalcogenide materials have been investigated as novel candidate anode materials for K‐ion batteries (KIBs). This pioneering study explores the electrochemical reaction between K‐ions and iron telluride. A detailed analysis is performed using in situ and ex situ methods, including X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and cyclic voltammetry (CV), following the initial discharging and charging processes. The reversible reaction mechanism, from the second cycle of the reaction of FeTe2 with K‐ions, is 2Fe + K5Te3 + K2Te ↔ 2FeTe1.1 + 1.8Te + 7K+ + 7e‐. Hollow carbon nanospheres housing iron telluride nanocrystals (FeTe2‐C) are synthesized via facile infiltration and a one‐step tellurization process to compensate for the substantial volume change of nanocrystals during the potassiation and depotassiation processes. Excellent electrochemical properties arise from the synergistic effect of the heterointerfaced FeTe1.1 and metalloid Te formed after one cycle and the yolk‐shell architecture with uniformly distributed nanocrystals are embedded in a carbon shell. FeTe2‐C electrode demonstrates remarkable long‐term cycle performance (171 mA h g‐1 for the 500th cycle at a high current density of 0.5 A g‐1) and an excellent rate capability (126 mA h g‐1), even at a high current density of 10 A g‐1.

Manipulating surface magnetic order in iron telluride.

Control of emergent magnetic orders in correlated electron materials promises new opportunities for applications in spintronics. For their technological exploitation, it is important to understand the role of surfaces and interfaces to other materials and their impact on the emergent magnetic orders. Here, we demonstrate for iron telluride, the nonsuperconducting parent compound of the iron chalcogenide superconductors, determination and manipulation of the surface magnetic structure by low-temperature spin-polarized scanning tunneling microscopy. Iron telluride exhibits a complex structural and magnetic phase diagram as a function of interstitial iron concentration. Several theories have been put forward to explain the different magnetic orders observed in the phase diagram, which ascribe a dominant role either to interactions mediated by itinerant electrons or to local moment interactions. Through the controlled removal of surface excess iron, we can separate the influence of the excess iron from that of the change in the lattice structure.

Evidence of the Plaquette Structure of Fe1+xTe Iron Telluride: Mössbauer Spectroscopy Study

Single‐crystalline Fe1+xTe iron telluride with off‐stoichiometric iron has been synthesized by the Bridgman method. The X‐ray diffraction and wave‐length‐dispersive X‐ray electron‐probe microanalysis characterization have shown Fe1.125Te stoichiometry of the samples. Spin‐polarized ab initio calculations of the electric field gradients around interstitial iron atoms for Fe1.125Te have shown that in the first and second coordination rings around interstitial iron, the spin and electron densities are strongly perturbed against the stoichiometric ones. Together with the interstitial iron this gives rise to three kinds of iron centers making up a round‐corner plaquette. The room‐temperature Mössbauer spectra measured at different incidence angles of gamma‐radiation are satisfactorily fitted utilizing the hyperfine parameters, calculated within the plaquette model. The low‐temperature data are well described with the assumption of an incommensurate collinear spin density wave (SDW) phase, showing consistency with neutron scattering data for the Fe1.125Te system.

Nanosized iron telluride for simultaneous nanomolar voltammetric determination of dopamine, uric acid, guanine and adenine

Herein, an efficient electrochemical sensor based on nano-sized iron telluride material (FeTe2) have been developed for the first time for simultaneous nanomolar determination of dopamine, uric acid, guanine and adenine molecules.

Effects of oxygen annealing on single crystal iron telluride

Among several Fe-based systems recently found to be superconducting are phases within the Fe1+dSe (FS) and Fe1+dSe1-xTex (FST) families, along with their intercalant-variants. A few groups have recently reported that isostructural Fe1+dTe (FT), although generally reported to be non-superconducting, exhibits trace superconductivity near 10 K upon exposure to oxygen. On the other hand, exposure to oxygen degrades superconductivity in FS, yet improves it in FST for high Te content as well as for high Fe content. We performed a comprehensive study to investigate the effects of oxygen exposure in bulk single crystals of Fe1±dTe using photoelectron spectroscopy, x-ray diffraction, electron diffraction, and Magnetic Field Modulated Microwave Spectroscopy. We report a change in the oxidation state from Te0 to Te4+ and Fe0 to Fe2+/3+ in agreement with others. However, this does not lead to superconductivity. In addition, oxygenation leads to the evolution of trace quantities of an iron-deficient minority phase consistent with an oriented crystalline intergrowth of FeTe2 within the Fe1+dTe crystal lattice.