Browse
Submit Data
Databases
API
Help

Dataset Information

23 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

High-Pressure Phases and Properties of the Mg₃Sb₂ Compound.

ABSTRACT: Pressure always plays an important role in influencing the structure configuration and electronic properties of materials. Here, combining density function theory and structure prediction algorithm, we systematically studied the Mg₃Sb₂ system from its phase transition to thermodynamic and electronic properties under high pressure. We find that two novel phases, namely Cm and C2/m, are stable under high pressure. Calculation results of phonon dispersions showed that both novel phases have no imaginary frequency, which indicates that the novel phases are thermodynamically stable. Due to the larger ionic radius of Sb compared to N, P, and As elements, the Mg₃Sb₂ compound shows a different electronic property at high pressure. The electronic calculations show that the novel phases of Cm and C2/m of Mg₃Sb₂ possess metallic behavior under high pressure. These results provide new insights for understanding the Mg₃Sb₂ compound.

SUBMITTER: Ding S

PROVIDER: S-EPMC7745450 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

High-Pressure Phases and Properties of the Mg3Sb2 Compound.

Ding Shicong S Su Ruiming R Cui Wenwen W Hao Jian J Shi Jingming J Li Yinwei Y

ACS omega 20201203 49

Pressure always plays an important role in influencing the structure configuration and electronic properties of materials. Here, combining density function theory and structure prediction algorithm, we systematically studied the Mg3Sb2 system from its phase transition to thermodynamic and electronic properties under high pressure. We find that two novel phases, namely Cm and C2/m, are stable under high pressure. Calculation results of phonon dispersions ...[more]

PMID: 33344844

Similar Datasets

Chemical bonding origin of the unexpected isotropic physical properties in thermoelectric Mg3Sb2 and related materials.

Project description:The Mg3Sb2 structure is currently being intensely scrutinized due to its outstanding thermoelectric properties. Usually, it is described as a layered Zintl phase with a clear distinction between covalent [Mg2Sb2]2- layers and ionic Mg2+ layers. Based on the quantitative chemical bonding analysis, we unravel instead that Mg3Sb2 exhibits a nearly isotropic three-dimensional bonding network with the interlayer and intralayer bonds being mostly ionic and surprisingly similar, which results in the nearly isotropic structural and thermal properties. The isotropic three-dimensional bonding network is found to be broadly applicable to many Mg-containing compounds with the CaAl2Si2-type structure. Intriguingly, a parameter based on the electron density can be used as an indicator measuring the anisotropy of lattice thermal conductivity in Mg3Sb2-related structures. This work extends our understanding of structure and properties based on chemical bonding analysis, and it will guide the search for and design of materials with tailored anisotropic properties.

| S-EPMC6226478 | biostudies-literature

Topological Phase Transition in Sb2Mg3 Assisted by Strain.

Project description:Topological insulating materials with dissipationless surface states promise potential applications in spintronic materials. Through density functional theory, we proposed a new class of topological phase transition in Sb2Mg3 on the basis of tensile strain. At the equilibrium state, Sb2Mg3 corresponds to a normal insulator, and under the influence of tensile strain, the band gaps are gradually tuned. At ε = 7.2%, the nontrivial phase is achieved due to spin-orbital coupling (SOC), and a nontrivial topological phase band gap of 0.22 eV is opened. As a result, the Dirac cone is locked in the bulk, which is associated to p x,y band crossing. Interestingly, the tuning of nontrivial topological properties with tensile strain leading to spin saturation indicates an orbital-filtering effect. The surface state of the Sb2Mg3 material is determined by the topological invariant, Z 2 = 1, at the critical tensile strain in the presence of the SOC effect. This study enhances the scope of topological insulators and current platforms to design new spintronic devices.

| S-EPMC6648217 | biostudies-literature

Electronic Structures and Photoelectric Properties in Cs3Sb2X9 (X = Cl, Br, or I) under High Pressure: A First Principles Study.

Project description:Lead-free perovskites of Cs3Sb2X9 (X = Cl, Br, or I) have attracted wide attention owing to their low toxicity. High pressure is an effective and reversible method to tune bandgap without changing the chemical composition. Here, the structural and photoelectric properties of Cs3Sb2X9 under high pressure were theoretically studied by using the density functional theory. The results showed that the ideal bandgap for Cs3Sb2X9 can be achieved by applying high pressure. Moreover, it was found that the change of the bandgap is caused by the shrinkage of the Sb-X long bond in the [Sb2X9]3- polyhedra. Partial density of states indicated that Sb-5s and X-p orbitals contribute to the top of the valence band, while Sb-5p and X-p orbitals dominate the bottom of the conduction band. Moreover, the band structure and density of states showed significant metallicity at 38.75, 24.05 GPa for Cs3Sb2Br9 and Cs3Sb2I9, respectively. Moreover, the absorption spectra showed the absorption edge redshifted, and the absorption coefficient of the Cs3Sb2X9 increased under high pressure. According to our calculated results, the narrow bandgap and enhanced absorption ability under high pressure provide a new idea for the design of the photovoltaic and photoelectric devices.

| S-EPMC9457912 | biostudies-literature

Manipulation of ionized impurity scattering for achieving high thermoelectric performance in n-type Mg3Sb2-based materials.

Project description:Achieving higher carrier mobility plays a pivotal role for obtaining potentially high thermoelectric performance. In principle, the carrier mobility is governed by the band structure as well as by the carrier scattering mechanism. Here, we demonstrate that by manipulating the carrier scattering mechanism in n-type Mg3Sb2-based materials, a substantial improvement in carrier mobility, and hence the power factor, can be achieved. In this work, Fe, Co, Hf, and Ta are doped on the Mg site of Mg3.2Sb1.5Bi0.49Te0.01, where the ionized impurity scattering crosses over to mixed ionized impurity and acoustic phonon scattering. A significant improvement in Hall mobility from ∼16 to ∼81 cm2⋅V-1⋅s-1 is obtained, thus leading to a notably enhanced power factor of ∼13 μW⋅cm-1⋅K-2 from ∼5 μW⋅cm-1⋅K-2 A simultaneous reduction in thermal conductivity is also achieved. Collectively, a figure of merit (ZT) of ∼1.7 is obtained at 773 K in Mg3.1Co0.1Sb1.5Bi0.49Te0.01 The concept of manipulating the carrier scattering mechanism to improve the mobility should also be applicable to other material systems.

| S-EPMC5635921 | biostudies-literature

Electronic Orbital Alignment and Hierarchical Phonon Scattering Enabling High Thermoelectric Performance p-Type Mg3Sb2 Zintl Compounds.

Project description:Environmentally friendly Mg3Sb2-based materials have drawn intensive attention owing to their promising thermoelectric performance. In this work, the electrical properties of p-type Mg3Sb2 are dramatically optimized by the regulation of Mg deficiency. Then, we, for the first time, found that Zn substitution at the Mg2 site leads to the alignment of p x,y and p z orbital, resulting in a high band degeneracy and the dramatically enhanced Seebeck coefficient, demonstrated by the DFT calculations and electronic properties measurement. Moreover, Zn alloying decreases Mg1 (Zn) vacancies formation energy and in turn increases Mg (Zn) vacancies and optimizes the carrier concentration. Simultaneously, the Mg/Zn substitutions, Mg vacancies, and porosity structure suppress the phonon transport in a broader frequency range, leading to a low lattice thermal conductivity of ~0.47 W m-1 K-1 at 773 K. Finally, a high ZT of ~0.87 at 773 K was obtained for Mg1.95Na0.01Zn1Sb2, exceeding most of the previously reported p-type Mg3Sb2 compounds. Our results further demonstrate the promising prospects of p-type Mg3Sb2-based material in the field of mid-temperature heat recovery.

| S-EPMC9079362 | biostudies-literature

Probing Efficient N-Type Lanthanide Dopants for Mg3Sb2 Thermoelectrics.

Project description:The recent discovery of n-type Mg3Sb2 thermoelectrics has ignited intensive research activities on searching for potential n-type dopants for this material. Using first-principles defect calculations, here, a systematic computational screening of potential efficient n-type lanthanide dopants is conducted for Mg3Sb2. In addition to La, Ce, Pr, and Tm, it is found that high electron concentration (?1020 cm-3 at the growth temperature of 900 K) can be achieved by doping on the Mg sites with Nd, Gd, Ho, and Lu, which are generally more efficient than other lanthanide dopants and the anion-site dopant Te. Experimentally, Nd and Tm are confirmed as effective n-type dopants for Mg3Sb2 since doping with Nd and Tm shows higher electron concentration and thermoelectric figure of merit zT than doping with Te. Through codoping with Nd (Tm) and Te, simultaneous power factor improvement and thermal conductivity reduction are achieved. As a result, high zT values of ?1.65 and ?1.75 at 775 K are obtained in n-type Mg3.5Nd0.04Sb1.97Te0.03 and Mg3.5Tm0.03Sb1.97Te0.03, respectively, which are among the highest values for n-type Mg3Sb2 without alloying with Mg3Bi2. This work sheds light on exploring promising n-type dopants for the design of Mg3Sb2 thermoelectrics.

| S-EPMC7739952 | biostudies-literature

Discovery of high-performance low-cost n-type Mg3Sb2-based thermoelectric materials with multi-valley conduction bands.

Project description:Widespread application of thermoelectric devices for waste heat recovery requires low-cost high-performance materials. The currently available n-type thermoelectric materials are limited either by their low efficiencies or by being based on expensive, scarce or toxic elements. Here we report a low-cost n-type material, Te-doped Mg3Sb1.5Bi0.5, that exhibits a very high figure of merit zT ranging from 0.56 to 1.65 at 300-725 K. Using combined theoretical prediction and experimental validation, we show that the high thermoelectric performance originates from the significantly enhanced power factor because of the multi-valley band behaviour dominated by a unique near-edge conduction band with a sixfold valley degeneracy. This makes Te-doped Mg3Sb1.5Bi0.5 a promising candidate for the low- and intermediate-temperature thermoelectric applications.

| S-EPMC5227096 | biostudies-literature

The novel high-pressure/high-temperature compound Co12P7 determined from synchrotron data.

Project description:The structural properties of cobalt phosphides were investigated at high pressures and temperatures to better understand the behavior of metal-rich phosphides in Earth and planetary inter-iors. Using single-crystal X-ray diffraction synchrotron data and a laser-heated diamond anvil cell, we discovered a new high pressure-temperature (HP-HT) cobalt phosphide, Co12P7, dodeca-cobalt hepta-phosphide, synthesized at 27 GPa and 1740 K, and at 48 GPa and 1790 K. Co12P7 adopts a structure initially proposed for Cr12P7 (space-group type P , Z =1), consisting of chains of edge-sharing CoP5 square pyramids and chains of corner-sharing CoP4 tetra-hedra. This arrangement leaves space for trigonal-prismatic channels running parallel to the c axis. Coupled disordering of metal and phospho-rus atoms has been observed in this structure for related M 12P7 (M = Cr, V) compounds, but all Co and P sites are ordered in Co12P7. All atomic sites in this crystal structure are situated on special positions. Upon decompression to ambient conditions, peak broadening and loss of reflections at high angles was observed, suggesting phase instability.

| S-EPMC7534243 | biostudies-literature

Revealing the Defect-Dominated Electron Scattering in Mg3Sb2-Based Thermoelectric Materials.

Project description:The thermoelectric parameters are essentially governed by electron and phonon transport. Since the carrier scattering mechanism plays a decisive role in electron transport, it is of great significance for the electrical properties of thermoelectric materials. As a typical example, the defect-dominated carrier scattering mechanism can significantly impact the room-temperature electron mobility of n-type Mg3Sb2-based materials. However, the origin of such a defect scattering mechanism is still controversial. Herein, the existence of the Mg vacancies and Mg interstitials has been identified by synchrotron powder X-ray diffraction. The relationship among the point defects, chemical compositions, and synthesis conditions in Mg3Sb2-based materials has been revealed. By further introducing the point defects without affecting the grain size via neutron irradiation, the thermally activated electrical conductivity can be reproduced. Our results demonstrate that the point defects scattering of electrons is important in the n-type Mg3Sb2-based materials.

| S-EPMC9620639 | biostudies-literature

Revelation of Inherently High Mobility Enables Mg3Sb2 as a Sustainable Alternative to n-Bi2Te3 Thermoelectrics.

Project description:Over the past years, thermoelectric Mg3Sb2 alloys particularly in n-type conduction, have attracted increasing attentions for thermoelectric applications, due to the multivalley conduction band, abundance of constituents, and less toxicity. However, the high vapor pressure, causticity of Mg, and the high melting point of Mg3Sb2 tend to cause the inclusion in the materials of boundary phases and defects that affect the transport properties. In this work, a utilization of tantalum-sealing for melting enables n-type Mg3Sb2 alloys to show a substantially higher mobility than ever reported, which can be attributed to the purification of phases and to the coarse grains. Importantly, the inherently high mobility successfully enables the thermoelectric figure of merit in optimal compositions to be highly competitive to that of commercially available n-type Bi2Te3 alloys and to be higher than that of other known n-type thermoelectrics at 300-500 K. This work reveals Mg3Sb2 alloys as a top candidate for near-room-temperature thermoelectric applications.

| S-EPMC6702648 | biostudies-literature