Evolution of Temperature-Induced Isostructural Phase Transition in a Newly Grown Layered FeTe₂ Single Crystal

Abstract

Layered FeTe 2 (l-FeTe 2 ) was supposed to be one of the most important compounds in the family of two-dimensional transition-metal dichalcogenides (2D TMDs) owing to the importance of an iron element and its predicted novel physical phenomena. However, 2D layered FeTe 2 is rarely reported because of its tendency to be stabilized in three-dimensional marcasite phase structures. Here, we report, for the first time, a pure and large-size l-FeTe 2 single crystal synthesized successfully in a P3̅ m1 hexagonal space group using a solid-state reaction method. Thermoanalysis and X-ray diffraction (XRD) data after annealing at different temperatures indicate that l-FeTe 2 is a metastable material. The results of electrical transport, magnetization, and in situ low-temperature XRD measurements confirm that l-FeTe 2 undergoes a first-order isostructural phase transition from 120 to 150 K, and we established a detailed correlation among these properties of l-FeTe 2 . l-FeTe 2 transforms from an insulating to metallic state at 120 K where the phase transition completes. In addition, the Shubnikov−de Haas (SdH) oscillation phenomenon is observed under a high magnetic field at 4 K.

Trends in CO2 Reduction on Transition Metal Dichalcogenide Edges

“…To the best of our knowledge, there are no previous studies of any of these materials as electrocatalysts for CO2RR. Whereas nanostructures of these materials have been reported in different phases (e.g., NbTe 2 in the 1T or distorted 1T phases, 28−31 orthorhombic marcasite structured CoTe 2 , 57 FeTe 2 in a hexagonal crystal structure, 58 and NiTe 2 and VTe 2 in the 1T phase 59,60 ), to the best of our knowledge, only CrTe 2 has been reported experimentally in the 2H phase, 61 although in theory all of the identified candidates should fulfill the thermodynamic and dynamic stability criteria used in this work. 47,48 Reaction Energy Diagrams.…”

Zero-Dimensional (Piperidinium)2MnBr4: Ring Puckering-Induced Isostructural Transition and Strong Electron–Phonon Coupling-Mediated Self-Trapped Exciton Emission

“…However, we could process the data and solve the structure with a reasonably good and reliable index (Table ). The crystal retains the same structure as that of the monoclinic P 2 1 / n space group after phase transition, suggesting an isostructural transition . Furthermore, we have used the atomic coordinates of RTP as the starting model for least square structure refinement for the HTP as it is an isostructural transition.…”

“…The crystal retains the same structure as that of the monoclinic P2 1 /n space group after phase transition, suggesting an isostructural transition. 53 Furthermore, we have used the atomic coordinates of RTP as the starting model for least square structure refinement for the HTP as it is an isostructural transition. For comparison of both the structures, such as bond lengths, bond angles, torsion angles, and so forth, we use the same atomic names for HTP as those used in RTP.…”

Electrical and Magnetoelectrical Transport in FeTe2 (100) Epitaxial Thin Films

“…The XRD pattern presents the typical (200) diffraction peak of FeTe 2 film (Figure a), indicating that it is epitaxially grown along the [100] crystallographic orientation without other impurity phases. The diffraction peak in Figure a is directly compared/indexed to the standard PDF diffraction peaks of orthorhombic marcasite phase m-FeTe 2 (PDF 89-1639) and also to those of hexagonal phase h-FeTe 2 , both of which share the same stoichiometric ratio. Obviously, the h-FeTe 2 phase is ruled out, and the orthorhombic marcasite phase m-FeTe 2 is confirmed in the present film.…”

“…20 Bulk single-crystalline m-FeTe 2 shows a plethora of magnetic states: for example, a ferromagnetic-based state below 35 K, an antiferromagnetic state at 35−79 K, and a paramagnetic state at 79 K. 20 One could naturally anticipate distinctive magnetic and transport properties of m-FeTe 2 when at the nanometer scale. To meet the progressive demand for both fundamental research and magnetic or electronic device applications based on the FeTe 2 structure, various types of FeTe 2 nanostructures, such as FeTe 2 nanosheets, 21 nanorods, 22 nanocrystallites, 23,24 nanoparticles, 25 nanocrystals, 26,27 layered single crystals, 28 and thin films, 29 have been synthesized with different preparation strategies, and the corresponding structure characteristics were discussed. For example, ultrathin h-FeTe 2 /m-FeTe 2 homostructures with thicknesses down to 6−90 nm were recently grown by a chemical vapor deposition method, and the temperature-dependent electrical transport of nanoflakes has been studied.…”