Wei Xie

• PhD
• Faculty Member at Shanghai University

Understanding the phase stability of elemental lithium (Li) is crucial for optimizing its performance in lithium-metal battery anodes, yet this seemingly simple metal exhibits complex polymorphism that requires proper accounting for quantum and anharmonic effects to capture the subtleties in its flat energy landscape. Here we address this challenge...

Understanding the phase stability of elemental lithium (Li) is crucial for optimizing its performance in next-generation battery anodes, yet this seemingly simple metal exhibits complex polymorphism that requires proper accounting...

Alternatives to lead- and tin-based perovskites for photovoltaics and optoelectronics are sought that do not suffer from the disadvantages of toxicity and low device efficiency of present-day materials. Here we report a study of the double perovskite Cs2TeI6, which we have synthesized in thin film form for the first time. Exhaustive trials conclude...

Double perovskite halides are a class of materials with diverse chemistries that are amenable to solution-based synthesis routes, and display a range of properties for a variety of potential applications. Starting from a consideration of the octahedral and tolerance factors of ~2000 candidate double-perovskite compounds, we compute structural, elec...

In this work we developed a practical and general modeling approach for thermal conductivity of metals and metal alloys that integrates ab initio and semiempirical physics-based models to maximize the strengths of both techniques. The approach supports creation of highly accurate, mechanistic, and extensible thermal conductivity modeling of alloys....

In this work we developed a practical and general modeling approach for thermal conductivity of metals and metal alloys that integrates ab initio and semiempirical physics-based models to maximize the strengths of both techniques. The approach supports creation of highly accurate, mechanistic, and extensible thermal conductivity modeling of alloys....

The past few years have witnessed unprecedented rapid improvement of the performance of a new class of photovoltaics based on halide perovskites. This progress has been achieved even though there is no generally accepted mechanism of the operation of these solar cells. Here we present a model based on bistable amphoteric native defects that account...

The past few years have witnessed unprecedented rapid improvement of the performance of a new class of photovoltaics based on halide perovskites. This progress has been achieved even though there is no generally accepted mechanism of the operation of these solar cells. Here we present a model based on bistable amphoteric native defects that account...

Phase diagram of Np-U-Zr, a key ternary alloy system of relevance for metallic nuclear fuels, is still largely undetermined. Here a thermodynamic model for the Np-U-Zr system is developed based on Muggianu extrapolation of our models for the U-Zr, Np-Zr, and Np-U binary systems, all employing the CALculation of PHAse Diagrams (CALPHAD) method. This...

The electronic structure and energetic stability of A$_2$BX$_6$ halide compounds with the cubic and tetragonal variants of the perovskite-derived K$_2$PtCl$_6$ prototype structure are investigated computationally within the frameworks of density-functional-theory (DFT) and hybrid (HSE06) functionals. The HSE06 calculations are undertaken for seven...

The electronic structure and energetic stability of A$_2$BX$_6$ halide compounds with the cubic and tetragonal variants of the perovskite-derived K$_2$PtCl$_6$ prototype structure are investigated computationally within the frameworks of density-functional-theory (DFT) and hybrid (HSE06) functionals. The HSE06 calculations are undertaken for seven...

Active oxygen materials that can rapidly transport and exchange oxygen with the environment play a critical role in many existing and developing technologies, e.g., solid oxide fuel cells (SOFCs), gas separation membranes, oxygen sensors, chemical looping devices, and memristors. In particular, reducing the working temperature of SOFCs, which is cr...

Hybrid two-dimensional (2D) lead halide perovskites have been employed in optoelectronic applications, including white light emission for light emitting diodes (LEDs). However, until now, there have been limited reports on white light emitting lead halide perovskites with experimental insights into the mechanism of the broad band emission. Here, we...

Perovskite solar cells, with efficiencies of 22.1%, are the only solution-processable technology to outperform multicrystalline silicon and thin film solar cells. While substantial progress has been made in scalability and stability, toxicity concerns drive the need for lead replacement, intensifying research into the broad palette of elemental sub...

The MAterials Simulation Toolkit (MAST) is a workflow manager and post-processing tool for ab initio defect and diffusion workflows. MAST codifies research knowledge and best practices for such workflows, and allows for the generation and management of easily modified and reproducible workflows, where data is stored along with workflow information...

The MAterials Simulation Toolkit (MAST) is a workflow manager and post-processing tool for ab initio defect and diffusion workflows. MAST codifies research knowledge and best practices for such workflows, and allows for the generation and management of easily modified and reproducible workflows, where data is stored along with workflow information...

In the Letter [Söderlind et al., J. Nucl. Mater. 444, 356 (2014)], Söderlind et al. state their interpretation that 1) we view electron correlation to be strong and including spin-orbit coupling (SOC) to be necessary for U metal and U-Zr alloy in our article [Xiong et al., J. Nucl. Mater. 443, 331 (2013)]. Further, they argue that 2) density functi...

The Np-U system has been rarely studied despite this alloy being a key binary subsystem of metallic nuclear fuels. This study aims to further the understanding of the phase stability of the Np-U system through ab initio calculations. We first examined an existing CALPHAD model based on available experimental phase boundary data. We then focused on...

Stability of oxygen point defects in Ruddlesden-Popper oxides (La$_{1-x}$Sr$_{x}$)$_{2}$MO$_{4{\pm}{\delta}}$ (M = Co, Ni, Cu) is studied with density functional theory calculations to determine their stable sites, charge states, and energetics as functions of Sr content ($x$), transition metal (M) and defect concentration ({\delta}). We demonstrat...

Stability of oxygen point defects in Ruddlesden-Popper oxides (La1-xSrx)2MO4±δ (M = Co, Ni, Cu) is studied with density functional theory calculations to determine their stable sites, charge states, and energetics as functions of Sr content (x), transition metal (M) and defect concentration (δ). We demonstrate that the dominant O point defects can...

In the Comment by Söderlind et al. [Phys. Rev. B 90, 157101 (2014)10.1103/PhysRevB.90.157101], the authors argue that (1) density functional theory (DFT), especially with all-electron methods, already models U metal and U-Zr alloy accurately; and (2) DFT+U results calculated at Ueff=1.24 for volume, enthalpy, and magnetic moments that they select f...

Stability of oxygen point defects in Ruddlesden–Popper oxides (La[subscript 1–x]Sr[subscript x])[subscript 2]MO[subscript 4±δ](M = Co, Ni, Cu) is studied with density functional theory calculations to determine their stable sites, charge states, and energetics as functions of Sr content (x), transition metal (M), and defect concentration (δ). We de...

In the Letter [J. Nucl. Mater. 444, 356 (2014)] and Comment [Phys Rev B 90, 157101 (2014)], Soderlind et al. argue that 1) DFT based on GGA already models U metal and U-Zr alloy accurately, and 2) DFT + U models them worse than DFT according to results they calculate or select from our recent study [Phys. Rev. B 88, 235128 (2013)]. Here we demonstr...

A new thermodynamic description of Np-Zr alloys is developed using the CALPHAD (CALculation of PHAse Diagrams) method based on available experimental information on phase equilibria, supplemented by ab initio energetics for end members that are not available in the standard CALPHAD unary database. The present thermodynamic description shows improve...

Ab initio calculations have been performed on all solid phases of U metal and U-Zr alloy, the basis of a promising metallic fuel for fast nuclear reactors. Based on generalized gradient approximation, both density functional theory (DFT) in its standard form and the so-called DFT plus Hubbard U (DFT+ U) modification are evaluated. The evolution of...

A new thermodynamic description of the U-Zr system is developed using the CALPHAD (CALculation of PHAse Diagrams) method with the aid of ab initio calculations. Thermodynamic properties, such as heat capacity, activities, and enthalpy of mixing, are well predicted using the improved thermodynamic description in this work. The model-predicted enthal...