High-throughput First-principles Calculations Research Articles

Lattice thermal conductivity including phonon frequency shifts and scattering rates induced by quartic anharmonicity in cubic oxide and fluoride perovskites

Lattice thermal conductivity ${\ensuremath{\kappa}}_{\mathrm{L}}$ is one of the key parameters involved in the design of microelectronics and energy-conversion devices. In determining the ${\ensuremath{\kappa}}_{\mathrm{L}}$, similar to the well-known cubic anharmonic effect, quartic anharmonicity is ubiquitous and also plays a crucial role in the final heat conduction of some compounds. In this paper, we use a high-throughput first-principles calculation method that combines self-consistent phonon (SCP) theory, compressive sensing techniques, and Boltzmann transport equation (BTE) to investigate the lattice thermal conductivity ${\ensuremath{\kappa}}_{\mathrm{L}}$ with the inclusion of cubic and quartic anharmonicity in 16 cubic oxide and fluoride perovskites. The BTE is solved on top of SCP theory for complete treatment of the quartic anharmonic effect that comprises four-phonon scattering and temperature-driven phonon frequency shift. In particular, only the ${\ensuremath{\kappa}}_{\mathrm{L}}$ within SCP theory is numerically valid for six of the 16 candidate perovskites, since the common calculation of BTE with harmonic phonons fails to estimate the ${\ensuremath{\kappa}}_{\mathrm{L}}$ due to the presence of imaginary frequencies in these materials. Our results exhibit that in addition to three-phonon scattering, the full inclusion of quartic anharmonicity is indispensable to capture a pertinent ${\ensuremath{\kappa}}_{\mathrm{L}}$ and rational temperature dependence of the ${\ensuremath{\kappa}}_{\mathrm{L}}$, while the consideration of only four-phonon scatterings (phonon frequency shifts) gives rise to a lower (higher) ${\ensuremath{\kappa}}_{\mathrm{L}}$ and stronger (weaker) temperature dependence. Meanwhile, we find a roughly linear relation between the ${\ensuremath{\kappa}}_{\mathrm{L}}$ and four-phonon scatterings in the 16 perovskites, which shows that the candidates with lower ${\ensuremath{\kappa}}_{\mathrm{L}}$ have stronger four-phonon scatterings. Moreover, very strong four-phonon scatterings are discovered in some cubic perovskites, especially in fluoride perovskites with imaginary harmonic phonons. The analyses of thermal conductivity spectrum ${\ensuremath{\kappa}}_{\mathrm{L}}(\ensuremath{\omega})$, scattering process, phase space, etc. reveal that the low-frequency four-phonon scattering rates in the structures with low ${\ensuremath{\kappa}}_{\mathrm{L}}$, e.g., $<1$ W/mK, are comparable to or even exceed those of three-phonon processes.

Enhanced anomalous Nernst effects in ferromagnetic materials driven by Weyl nodes

Based on high-throughput (HTP) first-principles calculations, we evaluated the anomalous Hall and anomalous Nernst conductivities of 266 transition-metal-based ferromagnetic compounds. Detailed analysis based on the symmetries and Berry curvatures reveals that the origin of singular-like behavior of anomalous Hall/Nernst conductivities can be mostly attributed to the appearance of Weyl nodes or nodal lines located in the proximity of the Fermi energy, which can be further tailored by external stimuli such as biaxial strains and magnetic fields. Moreover, such calculations are enabled by the automated construction of Wannier functions with a success rate of 92%, which paves the way to perform accurate HTP evaluation of the physical properties such as the transport properties using the Wannier interpolation.

Spontaneous valley polarization in two-dimensional organometallic lattices

2D ferrovalley materials that exhibit spontaneous valley polarization are both fundamentally intriguing and practically appealing to be used in valleytronic devices. Usually, the research on 2D ferrovalley materials is mainly focused on inorganic systems, severely suffering from in-plane magnetization. Here, we alternatively show by kp model analysis and high-throughput first-principles calculations that ideal spontaneous valley polarization is present in 2D organometallic lattice. We explore the design principle for organic 2D ferrovalley materials composed of (quasi-)planer molecules and transition-metal atoms in hexagonal lattice, and identify twelve promising candidates. These systems have a ferromagnetic or antiferromagnetic semiconducting state, and importantly they exhibit robust out-of-plane magnetization. The interplay between spin and valley, together with strong spin-orbit coupling of transition-metal atoms, guarantee the spontaneous valley polarization in these systems, facilitating the anomalous valley Hall effect. Our findings significantly broaden the scientific and technological impact of ferrovalley physics.

Unveiling the underlying mechanism of nitrogen fixation by a new class of electrocatalysts two-dimensional TM@g-C4N3 monosheets

The potential of TM atoms embedded g-C4N3 as a new class of electrocatalysts (TM@g-C4N3, TM = 3d, 4d and 5d transition metal) towards nitrogen reduction reaction (NRR) were systematically investigated through the combination of high-throughput screening and first-principles calculations. Among 30 candidate materials, TM@g-C4N3 (TM = V, Tc, Os, Pt) exhibited the highest activity for electrocatalytic N2 reduction to produce NH3. Particularly, V@g-C4N3 is identified as the most active catalyst for NRR with onset potential of −0.37 V. Interestingly, a volcano curve between Uonset (onset potential) and ΔEads(*N2) (the adsorption energy of N2) is established, and thus ΔEads(*N2) can be used as a descriptor to characterize the activity of catalysts. Among all investigated catalysts, the lowest onset potential of V@g-C4N3 can be attributed to its moderate adsorption energies for N2. After in-deep analysis of the intrinsic properties of the four catalysts, we found that the increasing order of catalytic activity is consistent with the increasing order of d-band center (εd) of the four catalysts. In addition, the excellent thermal stability of the four catalysts is verified via simulated annealing at 500 K for 10 ps. Furthermore, three catalysts TM@g-C4N3 (TM = V, Tc, Pt) demonstrate good selectivity. Therefore, V@g-C4N3 is a promising electrocatalyst for NRR. Our work opens the way for g-C4N3 as a new type of support to construct efficient single-atom catalyst for electrocatalytic ammonia synthesis. The predicted TM@g-C4N3 catalysts will provide useful guidance for experimental synthesis and rational design of catalysts in future.

Six new transformation pathways connecting simple crystal structures and common intermetallic crystal structures

Continuous pathways that connect different crystal structures can play a crucial role in determining the mechanisms with which structural phase transformations occur. The number of known pathways connecting metallic phases, such as the Bain path and the Burgers path, are limited. Here we discover six new pathways that connect the BCC, FCC, HCP and ω crystal structures to more complex intermetallic compound crystal structures. High throughput first-principles calculations of over 600 metallic binary AnBm compounds having compositions n:m of 1:1, 2:1 and 3:1 show that the newly discovered pathways can be initiated as a result of dynamical instabilities in the precursor phase. The pathways are initiated by specific precursor orderings of A and B atoms over the sites of the simpler parent crystal structures. We find that a large difference in the atomic radii between the constituents of the alloy is a common trigger of these instabilities. The results of this study have important implications for solid-state nucleation mechanisms of intermetallic compounds and suggest systematic approaches with which new intermetallic crystal structures can be discovered, especially in high dimensional composition spaces.

High-throughput computational screening of Sb–Te binary alloys for phase-change storage applications

As phase change materials (PCMs), Sb–Te based alloys have received a lot of attention in recent years. However, the mechanism for the formation of the alloy and its application as PCMs is not fully understood. The high-throughput First-principles calculations and melt-quench ab initio molecular dynamics simulations were adopted to explore the microstructure and properties of Sb–Te alloys in this work. The hetero-atomic interaction and disordered distribution make Sb–Te alloy with layered microstructure more stable. Although Sb1−xTex solid solution is the metastable phase, it is still stable for PCMs in the certain ranges of solid solubility (0.4 < x < 0.6). In this range, it has two distinct electrical states between crystalline and amorphous states, the strong isotropy in electric conductivity, and strong quasi two-dimensionality of the electronic states. Therefore, Sb1−xTex (0.4 < x < 0.6) solid solution and SbTe intermetallic compound are also potential candidates for PCMs worth considering in addition to Sb2Te3 intermetallic compound.

Ferroelectric and Room-Temperature Ferromagnetic Semiconductors in the 2D MIMIIGe2X6 Family: First-Principles and Machine Learning Investigations.

Inspired by experimentally discovering ferromagnetism and ferroelectricity in two-dimensional (2D) CrGeTe3 and CuInP2S6 with similar geometric structures, respectively, we systematically investigated ferroic properties in a large family of 2D MIMIIGe2X6 (MI and MII = metal elements, X = S/Se/Te) by combining high-throughput first-principles calculations and the machine learning method. We identified 12 stable 2D multiferroics containing simultaneously ferromagnetic (FM) and ferroelectric (FE) properties and 35 2D ferromagnets without FE polarization. Particularly, the predicted FM Curie temperatures (TC) of eight 2D FM+FE semiconductors are close to or above room temperature. The ferroelectricity originates from the spontaneous geometric symmetry breaking induced by the unexpected shift of Ge-Ge atomic pairs and the emergence of Ge lone pair electrons, which also strengthens the p-d orbital hybridization between X atoms and metal atoms, leading to enhanced super-super-exchange interactions and raising the FM TC. Our findings not only enrich the family of 2D ferroic materials and present room-temperature FM semiconductors but also disclose the mechanism of the emerging ferroelectricity and enhanced ferromagnetism, which sheds light on the realization of high temperature multiferroics as well as FM semiconductors.

DFTTK: Density Functional Theory ToolKit for high-throughput lattice dynamics calculations

In this work, we present a software package in Python for high-throughput first-principles calculations of thermodynamic properties at finite temperatures, which we refer to as DFTTK (Density Functional Theory ToolKit). DFTTK is based on the atomate package and integrates our experiences in the last decades on the development of theoretical methods and computational softwares. It includes task submissions on all major operating systems and task executions on high-performance computing environments. The distribution of the DFTTK package comes with examples of calculations of phonon density of states, heat capacity, entropy, enthalpy, and free energy under the quasi-harmonic phonon scheme for the stoichiometric phases of Al, Ni, Al3Ni, AlNi, AlNi3, Al3Ni4, and Al3Ni5, and the fcc solution phases treated using the special quasirandom structures at the compositions of Al3Ni, AlNi, and AlNi3.

Carrier and magnetism engineering for monolayer SnS2 by high throughput first-principles calculations* *Project supported by the National Natural Science Foundation of China (Grant No. 91833302).

Two-dimensional (2D) semiconducting tin disulfide (SnS2) has been widely used for optoelectronic applications. To functionalize SnS2 for extending its application, we investigate the stability, electronic and magnetic properties of substitutional doping by high throughput first-principles calculations. There are a lot of elements that can be doped in monolayer SnS2. Nonmetal in group A can introduce p-type and n-type carriers, while most metals in group A can only lead to p-type doping. Not only 3d, but also 4d and 5d transition metals in groups VB to VIIIB9 can introduce magnetism in SnS2, which is potentially applicable for spintronics. This study provides a comprehensive view of functionalization of SnS2 by substitutional doping, which will guide further experimental realization.

Unpredicted but It Exists: Trigonal Sc2Ru with a Significant Metal-Metal Charge Transfer.

The Sc2Ru compound, obtained by high-temperature synthesis, was found to crystallize in a new trigonal hP45 structure type [space group P3̅m1; a = 9.3583(9) Å and c = 11.285(1) Å]: Ru@Sc8 cubes, Ru@Sc12 icosahedra, and uncommon Ru@Sc10 sphenocoronae are the building blocks of a unique motif tiling the whole crystal space. According to density functional theory studies, Sc2Ru is a metallic compound characterized by multicenter interactions: a significant charge transfer occurs from Sc to Ru, indicating an unexpectedly strong ionic character of the interactions between the two transition metals. Energy calculations support our experimental results in terms of stability of this compound, contributing to the recurrent discussion on the limits of the high-throughput first-principles calculations for metallic materials design.

JAMIP: an artificial-intelligence aided data-driven infrastructure for computational materials informatics

Materials informatics has emerged as a promisingly new paradigm for accelerating materials discovery and design. It exploits the intelligent power of machine learning methods in massive materials data from experiments or simulations to seek new materials, functionality, and principles, etc. Developing specialized facilities to generate, collect, manage, learn, and mine large-scale materials data is crucial to materials informatics. We herein developed an artificial-intelligence-aided data-driven infrastructure named Jilin Artificial-intelligence aided Materials-design Integrated Package (JAMIP), which is an open-source Python framework to meet the research requirements of computational materials informatics. It is integrated by materials production factory, high-throughput first-principles calculations engine, automatic tasks submission and monitoring progress, data extraction, management and storage system, and artificial intelligence machine learning based data mining functions. We have integrated specific features such as an inorganic crystal structure prototype database to facilitate high-throughput calculations and essential modules associated with machine learning studies of functional materials. We demonstrated how our developed code is useful in exploring materials informatics of optoelectronic semiconductors by taking halide perovskites as typical case. By obeying the principles of automation, extensibility, reliability, and intelligence, the JAMIP code is a promisingly powerful tool contributing to the fast-growing field of computational materials informatics.

Data driven discovery of conjugated polyelectrolytes for optoelectronic and photocatalytic applications

Conjugated polyelectrolytes (CPEs), comprised of conjugated backbones and pendant ionic functionalities, are versatile organic materials with diverse applications. However, the myriad of possible molecular structures of CPEs render traditional, trial-and-error materials discovery strategy impractical. Here, we tackle this problem using a data-centric approach by incorporating machine learning with high-throughput first-principles calculations. We systematically examine how key materials properties depend on individual structural components of CPEs and from which the structure–property relationships are established. By means of machine learning, we uncover structural features crucial to the CPE properties, and these features are then used as descriptors in the machine learning to predict the properties of unknown CPEs. Lastly, we discover promising CPEs as hole transport materials in halide perovskite-based optoelectronic devices and as photocatalysts for water splitting. Our work could accelerate the discovery of CPEs for optoelectronic and photocatalytic applications.

The atlas of ferroicity in two-dimensional MGeX3 family: Room-temperature ferromagnetic half metals and unexpected ferroelectricity and ferroelasticity

Two-dimensional (2D) ferromagnetic and ferroelectric materials attract unprecedented attention due to the spontaneous-symmetry-breaking induced novel properties and multifarious potential applications. Here we systematically investigate a large family (148) of 2D MGeX3 (M = metal elements, X = O/S/Se/Te) by means of the high-throughput first-principles calculations, and focus on their possible ferroic properties including ferromagnetism, ferroelectricity, and ferroelasticity. We discover eight stable 2D ferromagnets including five semiconductors and three half-metals, 21 2D antiferromagnets, and 11 stable 2D ferroelectric semiconductors including two multiferroic materials. Particularly, MnGeSe3 and MnGeTe3 are predicted to be room-temperature 2D ferromagnetic half metals with Tc of 490 and 308 K, respectively. It is probably for the first time that ferroelectricity is uncovered in 2D MGeX3 family, which derives from the spontaneous symmetry breaking induced by unexpected displacements of Ge-Ge atomic pairs, and we also reveal that the electric polarizations are in proportion to the ratio of electronegativity of X and M atoms, and IVB group metal elements are highly favored for 2D ferroelectricity. Magnetic tunnel junction and water-splitting photocatalyst based on 2D ferroic MGeX3 are proposed as examples of wide potential applications. The atlas of ferroicity in 2D MGeX3 materials will spur great interest in experimental studies and would lead to diverse applications.

A generally reliable model for composition-dependent lattice constants of substitutional solid solutions

Solid solutioning has long been employed to improve the performance of enegineering materials, the degree of improvement generally correlates closely with the resultant lattice parameters. It is therefore of great importance for materials design to describe accurately the composition-dependent lattice constants of the solid solutions (SSs). However, existing models could hardly reproduce the usually non-linear relationship between the compositions and the lattice constants. Herein, we present a new model within the framework of virtual crystal approximation by taking into account both the size factor and the electronic effect. The model takes inputs as simple as the fundamental property parameters of the elementary substances and N referential SSs for an N-component system, and can then predict the lattice constant of SS with any composition within the system. Systematical validation using datasets obtained from high-throughput first-principles calculations and available experiments confirmed the high reliability and general applicability of our model for various substitutional SSs. Applications and limitations of the model as well as outlooks were also discussed. It is expected that this model will deepen the understanding of the relationship between the composition and the properties of materials.

All-boron planar ferromagnetic structures: from clusters to monolayers.

Ferromagnetism in all-boron planar clusters is revealed based on high-throughput first-principles calculations. Magnetic boron clusters induced from p electrons have been confirmed with large spins, e.g., S = 3 in a B34 cluster, which can be assembled to construct all-boron ferromagnetic monolayers. Notably, the ferromagnetic semiconductors of boron monolayers can be designed with the hybridization of a nonmagnetic B36 cluster in experimental synthesis. The ferromagnetism-paramagnetism transition and semiconductor-metal transition in these boron nanostructures will occur around 500 K according to ab initio molecular dynamics simulation, indicating the potential applications in nano-devices at room temperature. The coexisting ferromagnetic and semiconducting properties in boron monolayers are attributed to the unique multicenter bonds together with the modulation of structural symmetry, which might be worth experimental attempts in the future.

High-throughput computation on relationship between composition and magnetic phase transition temperature of LaFe&lt;sub&gt;11.5&lt;/sub&gt;Si&lt;sub&gt;1.5&lt;/sub&gt;-based magnetic refrigeration materials

La(Fe,&lt;i&gt; &lt;/i&gt;Si)&lt;sub&gt;13&lt;/sub&gt;-based alloys have attracted more and more attention, for they exhibit giant magnetocaloric effects. In order to broaden their magnetic refrigeration temperatureranges, achieving a series of La(Fe,&lt;i&gt; &lt;/i&gt;Si)&lt;sub&gt;13&lt;/sub&gt;-based alloys with different magnetic phase transition temperatures is of great significance. Unlike the traditional research method, in this paper, a high-throughput first-principles computation is performed to estimate the magnetic phase transition temperature of the LaFe&lt;sub&gt;11.5&lt;/sub&gt;Si&lt;sub&gt;1.5&lt;/sub&gt;-based alloy by employing AMS-BAND software and the mean field theory. We investigate the effects of doping Mn, Co, Ni, Al atoms and Fe-vacancies on the magnetic phase transition temperature of LaFe&lt;sub&gt;11.5&lt;/sub&gt;Si&lt;sub&gt;1.5&lt;/sub&gt;-based alloy, and give the phase diagrams between the composition and magnetic phase transition temperature. The calculated results demonstrate that the magnetic phase transition temperature of the LaFe&lt;sub&gt;11.5&lt;/sub&gt;Si&lt;sub&gt;1.5&lt;/sub&gt;-based alloy increases with the increase of Co and Ni content. However, it shows an opposite result when Mn atom is doped. As for the LaFe&lt;sub&gt;11.5&lt;/sub&gt;Si&lt;sub&gt;1.5&lt;/sub&gt;-based alloy with the Fe-vacancies, the research results indicate that the absence of Fe atoms will reduce the magnetic phase transition temperature. Furthermore, when Mn, Co, Ni and Al atoms are doped in the alloys with Fe-vacancies, the variation tendency of the magnetic phase transition temperature with the change of the doping content is similar to that without the Fe-vacancies. Some estimated results are compared with the experimental or reported results, showing that they are in good agreement with each other. The PDOS and the magnetic moments of Fe atoms in the Mn, Co, Ni, Al-doped LaFe&lt;sub&gt;11.5&lt;/sub&gt;Si&lt;sub&gt;1.5&lt;/sub&gt;-based alloys are calculated, in which only the doping of Mn atoms can increase the magnetic moments of Fe atoms. Using the method of high-throughput first-principles calculation can effectively reduce the research cost and improve the working efficiency. In addition, it can provide technical support for the experimental selection of magnetocaloric materials with appropriate magnetic phase transition temperatures.

Theoretical prediction of solution in Sc&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Y&lt;sub&gt;1–&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; Fe&lt;sub&gt;2&lt;/sub&gt; and order-disorder transitions in V&lt;sub&gt;2&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; Fe&lt;sub&gt;2(1–&lt;i&gt;x&lt;/i&gt;)&lt;/sub&gt;Zr

Alloying is an important way to increase the diversity of material structure and properties. In this paper, we start from Ising model considering nearest neighbor interaction, in which a ferromagnetic system corresponds to a low temperature phase separation and high temperature solid solution of binary alloy, while antiferromagnetic system corresponds to a low temperature ordered solid solution and a high temperature disorder. The high-throughput first-principles calculation based on the structure recognition is realized by the program SAGAR (structures of alloy generation and recognition) developed by our research group. By considering the contribution of structural degeneracy to the partition function, theoretical prediction of alloy materials can be carried out at finite temperature. Taking hydrogen storage alloy (Sc&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Y&lt;sub&gt;1–&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; Fe&lt;sub&gt;2&lt;/sub&gt; and V&lt;sub&gt;2&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; Fe&lt;sub&gt;2(1–&lt;i&gt;x&lt;/i&gt;)&lt;/sub&gt;Zr) for example, the formation energy of ground state (at zero temperature) can be obtained by the first-principles calculations. It is found that the formation energy of Sc&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Y&lt;sub&gt;1–&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; Fe&lt;sub&gt;2&lt;/sub&gt; is greater than zero, thereby inducing the phase separation at low temperature. The free energy will decrease with the temperature and concentration increasing, where the critical temperature of solid solution of alloy is determined according to the zero point of free energy. The formation energies of V&lt;sub&gt;2&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; Fe&lt;sub&gt;2(1–&lt;i&gt;x&lt;/i&gt;)&lt;/sub&gt;Zr are all lower than zero, and the ordered phase occurs at low temperature. The order-disorder transition temperature of V&lt;sub&gt;0.5&lt;/sub&gt;Fe&lt;sub&gt;1.5&lt;/sub&gt;Zr and V&lt;sub&gt;1.5&lt;/sub&gt;Fe&lt;sub&gt;0.5&lt;/sub&gt;Zr are both about 100 K, while the transition temperature of VFeZr is nearly 50 K. The calculation process will effectively improve the high throughput screening efficiency of alloy, and also provide relevant theoretical reference for experimental research.

Ammonia Synthesis Using Single-Atom Catalysts Based on Two-Dimensional Organometallic Metal Phthalocyanine Monolayers under Ambient Conditions.

We have identified three novel metal phthalocyanine (MPc, M = Mo, Re, and Tc) single-atom catalyst candidates with excellent predicted performance for the production of ammonia from electrocatalytic nitrogen reduction reaction (NRR) through a combination of high-throughput screening and first-principles calculations on a series of 3d, 4d, and 5d transition metals anchored onto extended Pc monolayer catalysts. Analysis of the energy band structures and projected density of states of N2-MPc revealed significant orbital hybridization and charge transfer between the adsorbed N2 and catalyst MPc, which accounts for the high catalytic activity. Among 30 MPc catalysts, MoPc and TcPc monolayers were found to be the most promising new NRR catalysts, as they exhibit excellent stability, low onset potential, and high selectivity. A comprehensive reaction pathway search found that the maximum free energy changes for the MoPc and TcPc monolayers are 0.33 and 0.54 eV, respectively. As a distinctive nature of this work, the hybrid reaction pathway was considered extensively and searched systematically. The onset potential of the hybrid pathway is found to be smaller than or comparable to that of the commonly known pure pathway. Thus, the hybrid path is highly competitive with low onset potential and high activity. The hybrid pathway is expected to have an important impact on future research on the mechanism of NRR, and it will open up a new way to explore the mechanism of the NRR reaction. We hope that our work will provide impetus to the creation of new catalysts for reduction of N2 to NH3. This work provides new insights into the rational design of NRR catalysts and explores novel reaction pathways under ambient or mild conditions.

Non-hydrostatic pressure-dependent structural and transport properties of BiCuSeO and BiCuSO single crystals

High-pressure experiments usually expect a hydrostatic condition, in which the physical properties of materials can be easily understood by theoretical simulations. Unfortunately, non-hydrostatic effect is inevitable in experiments due to the solidification of the pressure transmitting media under high pressure. Resultantly, non-hydrostaticity affects the accuracy of the experimental data and sometimes even leads to false phenomena. Since the non-hydrostatic effect is extrinsic, it is quite hard to analyze quantitatively. Here, we have conducted high pressure experiments on the layered BiCuXO (X = S and Se) single crystals and quantitatively analyzed their pronounced non-hydrostatic effect by high throughput first-principles calculations and experimental Raman spectra. Our experiments find that the BiCuXO single crystals sustain the tetragonal structure up to 55 GPa (maximum pressure in our experiment). However, their pressure-dependent Raman shift and electric resistance show anomalous behaviors. Through optimization of thousands of crystal structures in the high throughput first-principles calculations, we have obtained the evolution of the lattice constants under external pressures, which clearly substantiates the non-hydrostatical pressure exerted in BiCuXO crystals. Our work indicates that the high throughput first-principles calculations could be a handy method to investigate the non-hydrostatic effect on the structural and electronic properties of materials in high pressure experiments.

Rapid screening of alloy elements to improve the elastic properties of dilute Pt-based alloys: High-throughput first-principles calculations and modeling

Platinum (Pt)-based dilute solid solutions are an important category of high-temperature alloys and bond coatings. In this study, the effects of 33 alloying elements on the mechanical and electronic properties of dilute Pt-based solid solutions are systematically investigated under atom relaxation and full relaxation using first-principles calculations based on density functional theory. The negative mixing enthalpy of Pt-dilute solid solutions means that the solubility of the solute elements in the Pt-based dilute alloys is energetically favorable at 0 K. Niobium, rhenium, and scandium are promising candidate elements for increasing the hardness and ductility of dilute Pt-based solid solutions. In addition, the electronic basis for the mechanical properties of Pt-dilute solid solutions is investigated in terms of the electronic density and mean bond population. The results demonstrate that the Pt–X bond lengths are shorter than the Pt–Pt bond length, resulting in greater hardness. Moreover, the model for the composition dependent elastic properties is built based on the CALPHAD approach, which will be used to the Pt-based multiphase alloys in the future. As certain alloying elements improve the hardness and ductility of Pt, this research expands our knowledge of the mechanism of dilute Pt-based solid solutions and provides a basis for next-generation superalloys or bond coatings at higher temperatures.