arXiv subjects

Satyesh K. Yadav

Publications and source records attributed to Satyesh K. Yadav.

8 recordsLinked to original sources

arXiv2026

Let Cyclic Electrochemical Data Speak for Your Energy Storage Material and Processing

Efforts to improve performance, like energy and power density of electrochemical energy storage devices (batteries, capacitors, and super-capacitors), are being made using a range of experimental and computational tools. The most common strategy involves exploring new material chemistries, developing advanced synthesis routes, and advanced ways to integrate these materials into device architectures. Although it is desirable to evaluate the performance of such efforts at a fixed cell format, not all studies conduct testing across the same cell formats. Specific performance normalized per mass of active material has been adopted as a universal indicator of performance, but it is not a reliable way to compare across cell formats. We propose a new mass normalization, i.e., the mass of electrochemical participants, to calculate specific performance. This new specific performance makes it possible to efficiently compare the efficacy of materials, synthesis, and cell assembly across different cell formats. We developed a framework to comprehensively report materials, synthesis, and cell assembly, and performance data, which facilitates succinctly reporting all performance indicators, including charge discharge curves over all cyclic stability assessments. The new specific performance and mass of the electrochemical participants per unit area of the electrode allows us to create a calculator to estimate performance at any commercial device-level cell format from measured data at the laboratory-level cell. The new specific performance also helps in optimizing the coating thickness and the loading of the active material. The framework can be adapted by journals to facilitate the reporting of data in a comprehensive way. Leveraging this framework, we have also compiled a database (hosted at https://power.tattvasar.com/) by extracting pertinent data from existing literature.

cond-mat.mtrl-sci↗

arXiv2025

Molecular Mechanisms of Polymer Crosslinking via Thermal Activation

Developing efficient and universal polymer crosslinking strategies is pivotal for advanced material design, especially for challenging matrixes like polyethylene, polypropylene, and polystyrene. Traditional crosslinkers such as divinylbenzene (DVB) often requires high-temperature radical initiators and are limited by poor compatibility with saturated hydrocarbon matrices. In contrast, bis-diazirine (BD) crosslinkers offer a promising alternative by harnessing thermally or photochemically generated carbene intermediates for highly selective C-H bond insertions. Here, we employ density functional theory (DFT)-based electronic structure calculations to elucidate the molecular mechanisms and energetics of BD-mediated crosslinking across PE, PP, and PS. We demonstrate that BD enables efficient covalent linkage through low free energy barriers , facilitating crosslinking at moderate temperatures without catalysts and with minimal sensitivity to polymer chain length. Moreover, BD exhibits selective reactivity towards the tertiary and secondary C-H bonds in PP and PS, respectively. Comparative analysis shows that BD dramatically outperforms DVB, especially in saturated polymers, enabling reaction times that are orders of magnitude faster. Our findings provide atomistic insights into BD crosslinker reactivity and establish a mechanistic foundation for next-generation, universal C-H activation-based crosslinking technologies.

physics.chem-ph↗

arXiv2022

Designing a thermodynamically stable and intrinsically ductile refractory alloy

Developing ductile refractory BCC alloys has remained a challenge. The intrinsic ductility (D) of an alloy is the ratio of surface energy ($γ_s$) and unstable stacking fault energy ($γ_{usfe}$). Lowering the valence electron concentration has been shown to improve the intrinsic ductility of refractory alloys. However, Re has been widely used to ductilize W, contrary to the low valency criteria suggested in the literature. Here we use density functional theory to calculate the enthalpy of formation, $γ_{usfe}$ and $γ_s$ of Group IV, V, VI elements and their 25 equiatomic binary alloys in BCC crystal structure. We found that positive enthalpy leads to a considerable reduction in $γ_{usfe}$ compared to composition averaged value, resulting in improved intrinsic ductility. Enthalpy is maximum at the equiatomic concentrations indicating the highly repulsive interaction between the alloy constituents and vicer-versa. We found that the repulsive interaction between the alloy constituents leads to a reduction in $γ_{usfe}$, making alloys intrinsically ductile.

cond-mat.mtrl-sci↗

arXiv2020

Nb Implanted BaO as a Support for Gold Single Atoms

Using first-principles modelling based on density functional theory we show that oxides implanted with transition metal can act as support for Au single atoms, which are stable against agglomeration. In our previous work we have shown that implanted transition metal, doped in BaO is stable as interstitial in various charge states by transferring the excess charge to an acceptor level close to VBM. Taking Nb as an example we show that single atom Au has its Fermi level close to the VBM of BaO and hence is able to accept charge from the dopant. This charge transfer process between Nb and Au helps Au atoms bind strongly on the doped BaO support. We also show that these charged Au atoms repel each other and prefer to remain atomically dispersed preventing cluster formation. Substitutional doping of transition metals have earlier been reported to bind Au atoms. However, if doped at interstitial sites, they can bind more Au atoms; for example, 5 Au atoms can be anchored per Nb dopant present in BaO interstitial, compared to 3 Au atoms when Nb is doped at substitutional site. This work paves the way for an altogether new technique of stabilizing noble metal single atoms on transition metal doped oxides.

cond-mat.mtrl-sci↗

arXiv2020

On the Origin of Precipitation of Transition Metals Implanted in MgO

Transition metals implanted in single crystal MgO can precipitate out at grain boundaries or remain embedded in bulk. Using first-principles calculations based on density functional theory we have calculated the thermodynamic stability and diffusion coefficients of the implanted ions to explain Fe and Ni precipitation in MgO. Experimentally it has been observed that some of the Fe atoms precipitate out, while few Fe atoms in 2+ and 3+ charge states remain embedded in the lattice. Our simulation shows that at 600 K (typical annealing temperature) while neutral iron in MgO would migrate 1 $μ$m in few microseconds, it takes several years for the charged Fe ions to migrate the same distance. On the other hand, Ni ions in all its charge states (neutral, 1+, 2+, and 3+) would migrate 1 $μ$m in just few microseconds, at 600 K. This explains the experimental observation that implanted Ni always precipitates out. Our study paves a way forward to predict if ions implanted in stable oxide will be stable or will precipitate out.

cond-mat.mtrl-sci↗

arXiv2020

Fluorine Intercalated Graphene: Formation of a 2D Spin Lattice through Pseudoatomization

A suspended layer made up of ferromagnetically ordered spins could be created between two mono/multilayer graphene through intercalation. Stability and electronic structure studies show that, when fluorine molecules are intercalated between two mono/multilayer graphene, their bonds get stretched enough ($\sim$ 1.9$-$2.0 Å) to weaken their molecular singlet eigenstate. Geometrically, these stretched molecules form a pseudoatomized fluorine layer by maintaining a van der Waals separation of $\sim$ 2.6 Å from the adjacent carbon layers. As there is a significant charge transfer from the adjacent carbon layers to the fluorine layers, a mixture of triplet and doublet states stabilize to induce local spin-moments at each fluorine sites and in turn form a suspended 2D spin lattice. The spins of this lattice align ferromagnetically with nearest neighbour coupling strength as large as $\sim$ 100 meV. Our finite temperature \textit {ab initio} molecular dynamics study reveals that the intercalated system can be stabilized up to a temperature of 100 K with an average magnetic moment of $\sim$ 0.6 $μ_{B}$/F. However, if the graphene layers can be held fixed, the room temperature stability of such a system is feasible.

cond-mat.mes-hall↗

arXiv2019

Stability of Implanted Transition Metal Dopants in Rock-salt Oxides

Transition metals (TMs) implanted in oxides with rock-salt crystal structures (for example MgO and BaO) are assumed to substitute cations (Mg in case of MgO) from the lattice sites. We show that not all implanted TMs substitute cations but can be stable in interstitial sites as well. Stability of TM (Sc--Zn) dopants in various charge states in MgO and BaO has been investigated in the framework of density functional theory. We propose an effective way to calculate stability of implanted metals that let us predict site preference (interstitial or substitution) of the dopant in the host. We find that two factors govern the preference for an interstitial site: i) relative ionic radius and ii) relative oxygen affinity of cation and the TM dopants. If the radius of the cation is much larger than TM dopant, as in BaO, TM atoms always sit at interstitial sites. On the other hand, if the radius of the cation is comparable to that of the dopant TM, as in case of MgO, the transition of the preferred defect site, from substituting lattice Mg atom (Sc to Mn) to occupying interstitial site (Fe to Zn) is observed. This transition can be attributed to the change in the oxygen affinity of the TM atoms from Sc to Zn. Our results also explain experiments on Ni and Fe atoms implanted in MgO. This is the first-time we have shown that TM dopants can be stable at interstitial sites in stable compounds, which could potentially give rise to exotic properties.

cond-mat.mtrl-sci↗

arXiv2015

Band-gap and Band-edge Engineering of Multicomponent Garnet Scintillators: A First-principles Study

Complex doping schemes in RE$_3$Al$_5$O$_{12}$ (RE=rare earth element) garnet compounds have recently led to pronounced improvements in scintillator performance. Specifically, by admixing lutetium and yttrium aluminate garnets with gallium and gadolinium, the band-gap was altered in a manner that facilitated the removal of deleterious electron trapping associated with cation antisite defects. Here, we expand upon this initial work to systematically investigate the effect of substitutional admixing on the energy levels of band edges. Density functional theory was used to survey potential admixing candidates that modify either the conduction band minimum (CBM) or valence band maximum (VBM). We considered two sets of compositions based on Lu$_3$B$_5$O$_{12}$ where B = Al, Ga, In, As, and Sb; and RE$_3$Al$_5$O$_{12}$, where RE = Lu, Gd, Dy, and Er. We found that admixing with various RE cations does not appreciably effect the band gap or band edges. In contrast, substituting Al with cations of dissimilar ionic radii has a profound impact on the band structure. We further show that certain dopants can be used to selectively modify only the CBM or the VBM. Specifically, Ga and In decrease the band gap by lowering the CBM, while As and Sb decrease the band gap by raising the VBM. These results demonstrate a powerful approach to quickly screen the impact of dopants on the electronic structure of scintillator compounds, identifying those dopants which alter the band edges in very specific ways to eliminate both electron and hole traps responsible for performance limitations. This approach should be broadly applicable for the optimization of electronic and optical performance for a wide range of compounds by tuning the VBM and CBM.

cond-mat.mtrl-sci↗