Influence of structure and thermodynamic stability on electronic properties of two-dimensional SiC, SiGe, and GeC alloys

Guilhon, Ivan; Teles, L. K.; Marques, Marcelo; Pelá, Ronaldo Rodrigues; Bechstedt, F.

doi:10.1103/physrevb.92.075435

Cited by 61 publications

(32 citation statements)

References 66 publications

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“…As such, the internal energy is calculated by , where x j is the probability distribution for the occurence of a cluster with configuration j . As described elsewhere 51,52,54,55 , the occurence probability x j of equivalence class j can be estimated by the constrained minimization of the Helmholtz free energy, i.e., , through the GQCA, by considering the probability normalization and average of composition x as calculated by 51,52,57 . Thereby, the distribution is given bywhere , and is an adimensional parameter obtained by the average composition constrain, and g j is the degeneracy defined to each j as described in Table 1.…”

Section: Cluster Expansion and Thermodynamic Treatmentmentioning

confidence: 99%

Thermodynamic Stability and Structural Insights for CH3NH3Pb1−xSixI3, CH3NH3Pb1−xGexI3, and CH3NH3Pb1−xSnxI3 Hybrid Perovskite Alloys: A Statistical Approach from First Principles Calculations

Guedes-Sobrinho

Guilhon

Marques

et al. 2019

Sci Rep

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The recent reaching of 20% of conversion efficiency by solar cells based on metal hybrid perovskites (MHP), e.g., the methylammonium (MA) lead iodide, CH 3 NH 3 PbI 3 (MAPbI 3 ), has excited the scientific community devoted to the photovoltaic materials. However, the toxicity of Pb is a hindrance for large scale commercial of MHP and motivates the search of another congener eco-friendly metal. Here, we employed first-principles calculations via density functional theory combined with the generalized quasichemical approximation to investigate the structural, thermodynamic, and ordering properties of MAPb 1− x Si x I 3 , MAPb 1− x Ge x I 3 , and MAPb 1− x Sn x I 3 alloys as pseudo-cubic structures. The inclusion of a smaller second metal, as Si and Ge, strongly affects the structural properties, reducing the cavity volume occupied by the organic cation and limitating the free orientation under high temperature effects. Unstable and metaestable phases are observed at room temperature for MAPb 1− x Si x I 3 , whereas MAPb 1− x Ge x I 3 is energetically favored for Pb-rich in ordered phases even at very low temperatures. Conversely, the high miscibility of Pb and Sn into MAPb 1− x Sn x I 3 yields an alloy energetically favored as a pseudo-cubic random alloy with tunable properties at room temperature.

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Section: Cluster Expansion and Thermodynamic Treatmentmentioning

confidence: 99%

Thermodynamic Stability and Structural Insights for CH3NH3Pb1−xSixI3, CH3NH3Pb1−xGexI3, and CH3NH3Pb1−xSnxI3 Hybrid Perovskite Alloys: A Statistical Approach from First Principles Calculations

Guedes-Sobrinho

Guilhon

Marques

et al. 2019

Sci Rep

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“…Multilayer SiC resembles the bulk SiC in their structure and properties. Like bulk SiC, both multilayer and bilayer SiC have indirect band gap [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

“…Multilayer SiC resembles the bulk SiC in their structure and properties. Like bulk SiC, both multilayer and bilayer SiC have indirect band gap [ 18 , 19 , 20 ]. A detailed discussion about the structure, properties, and applications of 2D SiC has been provided in our very recent review paper [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

The Creation of True Two-Dimensional Silicon Carbide

et al. 2021

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This paper reports the successful synthesis of true two-dimensional silicon carbide using a top-down synthesis approach. Theoretical studies have predicted that 2D SiC has a stable planar structure and is a direct band gap semiconducting material. Experimentally, however, the growth of 2D SiC has challenged scientists for decades because bulk silicon carbide is not a van der Waals layered material. Adjacent atoms of SiC bond together via covalent sp3 hybridization, which is much stronger than van der Waals bonding in layered materials. Additionally, bulk SiC exists in more than 250 polytypes, further complicating the synthesis process, and making the selection of the SiC precursor polytype extremely important. This work demonstrates, for the first time, the successful isolation of 2D SiC from hexagonal SiC via a wet exfoliation method. Unlike many other 2D materials such as silicene that suffer from environmental instability, the created 2D SiC nanosheets are environmentally stable, and show no sign of degradation. 2D SiC also shows interesting Raman behavior, different from that of the bulk SiC. Our results suggest a strong correlation between the thickness of the nanosheets and the intensity of the longitudinal optical (LO) Raman mode. Furthermore, the created 2D SiC shows visible-light emission, indicating its potential applications for light-emitting devices and integrated microelectronics circuits. We anticipate that this work will cause disruptive impact across various technological fields, ranging from optoelectronics and spintronics to electronics and energy applications.

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“…The conductivity of germanium without doping or alloying is not good, and germanium and carbon composite material has been proposed as a potential anode material with good conductivity due to sp 2 -carbon being in composite [ 22 , 23 , 24 , 25 ]. Recently, a graphene-like Ge/C composite called germagraphene (g-GeC) has been proposed, predicted by first-principles calculations to be a two-dimensional nonmagnetic semiconductor with a direct band gap of about 2.1 eV at K (K’) points [ 26 , 27 , 28 , 29 , 30 ]. The structure is the same as germanene, silicene and other honeycomb-like structures, but different from germanium is that it is a plane structure without buckling height [ 29 ].…”

Section: Introductionmentioning

confidence: 99%

Adsorption of K Ions on Single-Layer GeC for Potential Anode of K Ion Batteries

Fan

et al. 2021

Nanomaterials

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Potassium ion batteries (KIBs) are considered as promising alternatives to lithium ion batteries (LIBs), following the rapid increase of demand for portable devices, and the development of electric vehicles and smart grids. Though there has been a promising breakthrough in KIB tech niques, exploring the promising anode materials for KIBs is still a challenge. Rational design with first-principle methods can help to speed up the discovery of potential anodes for KIBs. With density functional calculations, GeC with graphene-like 2D structure (g-GeC) is shown to be a desired anode material for applications in KIBs. The results show that the 2D g-GeC with a high concentration of K ions is thermodynamically stable, due to the strong interaction between C and Ge in GeC layer with the proper interaction between K and GeC. The storage capacity can be about 320 mAh/g, higher than that (279 mAh/g) in graphite. The low energy barrier (0.13 eV) of K ions diffusion on the honeycomb structure with proper voltage profile indicates the fast charge transfer. These theoretical finds are expected to stimulate the future experimental works in KIBs.

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Influence of structure and thermodynamic stability on electronic properties of two-dimensional SiC, SiGe, and GeC alloys

Cited by 61 publications

References 66 publications

Thermodynamic Stability and Structural Insights for CH3NH3Pb1−xSixI3, CH3NH3Pb1−xGexI3, and CH3NH3Pb1−xSnxI3 Hybrid Perovskite Alloys: A Statistical Approach from First Principles Calculations

Thermodynamic Stability and Structural Insights for CH3NH3Pb1−xSixI3, CH3NH3Pb1−xGexI3, and CH3NH3Pb1−xSnxI3 Hybrid Perovskite Alloys: A Statistical Approach from First Principles Calculations

The Creation of True Two-Dimensional Silicon Carbide

Adsorption of K Ions on Single-Layer GeC for Potential Anode of K Ion Batteries

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