New n-type Zintl Phases for Thermoelectrics: Discovery, Structural Characterization and Band Engineering of the Compounds A2CdP2 (A = Sr, Ba, Eu)

Zintl phases, owing to their complex crystal structures and intricate chemical bonding, have recently been recognized as promising candidates for thermoelectric (TE) applications. Band engineering, including band convergence has been shown to be an effective way to enhance the thermoelectric performance of such materials. In this work, a series of emerging TE materials, the isostructural Zintl phases with the general formula A2CdP2 (A = Sr, Ba, Eu) are presented for the first time. Their structures, established from single-crystal X-ray diffraction methods, show them to crystallize with the orthorhombic Yb2CdSb2 structure type, with first-principles calculations on phase stability confirming that Ba2CdP2 and Sr2CdP2 are thermodynamically stable. Computationally, it was found that both Ba2CdP2 and Sr2CdP2 have the potential to exhibit high n-type TE performance (0.6 and 0.7 relative to the n-type PbTe, a reference TE material). To optimize the TE performance, band engineering strategies, including isovalent substitution and cation mutations, were investigated. From the band engineering of Ba2CdP2 via isovalent substitution of Sr on a single Ba site, leading to the quaternary composition SrBaCdP2, it can be suggested that increasing the conduction band valley degeneracy is an effective way to improve the n-type TE performance by three-fold. Moreover, first-principles defect calculations reveal that both Ba2CdP2 and SrBaCdP2 are n-type dopable, adding these compounds to a small list of rare n-type dopable Zintl phases. The band engineering strategies used in this work are equally applicable to other TE materials, either for optimization of existing TE materials or designing new materials with desired properties.

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Crystal structure of the layered arsenide Rb3Cu3As2

Acta Crystallographica Section C Structural Chemistry ◽

10.1107/s2053229618014341 ◽

2018 ◽

Vol 74 (12) ◽

pp. 1715-1718 ◽

Cited By ~ 2

Author(s):

Alexander Ovchinnikov ◽

Hua He ◽

Svilen Bobev

Keyword(s):

Crystal Structure ◽

First Principles ◽

First Principles Calculations ◽

X Ray Diffraction ◽

Zintl Phases ◽

X Ray ◽

Bonding Analysis ◽

Electron Counting ◽

Valence Electrons ◽

Weak Attraction

The crystal structure of a new arsenide, Rb3Cu3As2 (trirubidium tricopper diarsenide), has been established from single-crystal X-ray diffraction data. This compound crystallizes in the K3Cu3P2 type, with layers of interlinked CuAs2 units. The partitioning of the available valence electrons yields the charge-balanced composition (Rb+)3(Cu+)3(As3–)2, placing this phase in a broad field of transition-metal-containing Zintl phases. First-principles calculations confirm a semiconducting ground state, in accordance with electron-counting considerations. Chemical bonding analysis reveals strong covalent Cu—As bonds and ionic Rb...As interactions. In addition, a weak attraction is found between the Cu atoms, possibly pointing toward cuprophilic interactions.

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Site preference and atomic ordering in the ternary Rh5Ga2As: first-principles calculations

Zeitschrift für Kristallographie - Crystalline Materials ◽

10.1515/zkri-2021-2019 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Nilanjan Roy ◽

Sucharita Giri ◽

Harshit ◽

Partha P. Jana

Keyword(s):

Total Energy ◽

First Principles ◽

Density Functional ◽

Structure Type ◽

Site Preference ◽

X Ray Diffraction ◽

Atomic Ordering ◽

Functional Theory ◽

The Stability ◽

Bonding Characteristics

Abstract The site preference and atomic ordering of the ternary Rh5Ga2As have been investigated using first-principles density functional theory (DFT). An interesting atomic ordering of two neighboring elements Ga and As reported in the structure of Rh5Ga2As by X-ray diffraction data only is confirmed by first-principles total-energy calculations. The previously reported experimental model with Ga/As ordering is indeed the most stable in the structure of Rh5Ga2As. The calculation detected that there is an obvious trend concerning the influence of the heteroatomic Rh–Ga/As contacts on the calculated total energy. Interestingly, the orderly distribution of As and Ga that is found in the binary GaAs (Zinc-blende structure type), retained to ternary Rh5Ga2As. The density of states (DOS) and Crystal Orbital Hamiltonian Population (COHP) are calculated to enlighten the stability and bonding characteristics in the structure of Rh5Ga2As. The bonding analysis also confirms that Rh–Ga/As short contacts are the major driving force towards the overall stability of the compound.

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The origins of charge separation in anisotropic facet photocatalysts investigated through first-principles calculations

RSC Advances ◽

10.1039/d1ra01711j ◽

2021 ◽

Vol 11 (30) ◽

pp. 18500-18508

Author(s):

Shun-Chiao Chan ◽

Yu-Lin Cheng ◽

Bor Kae Chang ◽

Che-Wun Hong

Keyword(s):

First Principles ◽

Charge Separation ◽

First Principles Calculations ◽

Design And Development ◽

First Time

The anisotropic (110)/(100) facet junction built-in potential in SrTiO3 is estimated at 2.9 V using DFT for the first time, which can help in further design and development of efficient photocatalysts using such anisotropic-facet engineering.

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Structural, Superconducting and Magnetic Properties of La3-XRxNi2B2N3-δ with R = Ce, Pr, Nd

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.170.165 ◽

2011 ◽

Vol 170 ◽

pp. 165-169 ◽

Cited By ~ 2

Author(s):

Tahir Ali ◽

Ernst Bauer ◽

Gerfried Hilscher ◽

Herwig Michor

Keyword(s):

Magnetic Properties ◽

Structure Type ◽

The Body ◽

Spin Reorientation ◽

Superconducting Transition ◽

X Ray Diffraction ◽

Range Magnetic Order ◽

Long Range Magnetic Order ◽

First Time ◽

Magnetic Pair

We report on structural and superconducting properties of La3-xRxNi2B2N3- where La is substituted by the magnetic rare-earth elements Ce, Pr, Nd. The compounds Pr3Ni2B2N3- and Nd3Ni2B2N3- are characterized for the first time. Powder X-ray diffraction confirmed all samples R3Ni2B2N3- with R = La, Ce, Pr, Nd and their solid solutions to crystallize in the body centered tetragonal La3Ni2B2N3 structure type. Superconducting and magnetic properties of La3-xRxNi2B2N3- were studied by resistivity, specific heat and susceptibility measurements. While La3Ni2B2N3- has a superconducting transition temperature Tc ~ 14 K, substitution of La by Ce, Pr, and Nd leads to magnetic pair breaking and, thus, to a gradual suppression of superconductivity. Pr3Ni2B2N3- exibits no long range magnetic order down to 2 K, Nd3Ni2B2N3- shows ferrimagnetic ordering below TC =17 K and a spin reorientation transition to a nearly antiferromagnetic state at 10 K.

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First principles calculations, neutron, and x-ray diffraction investigation of Y3Ni13B2, Y3Co13B2, and Y3Ni10Co3B2

Journal of Applied Physics ◽

10.1063/1.4862163 ◽

2014 ◽

Vol 115 (2) ◽

pp. 023907

Author(s):

N. Plugaru ◽

M. Valeanu ◽

R. Plugaru ◽

J. Campo

Keyword(s):

First Principles ◽

First Principles Calculations ◽

X Ray Diffraction ◽

X Ray

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Experimental and computational investigations of TiIrB: a new ternary boride with Ti1+x Rh2−x+y Ir3−y B3-type structure

Zeitschrift für Naturforschung B ◽

10.1515/znb-2021-0121 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Jan P. Scheifers ◽

Kate A. Gibson ◽

Boniface P. T. Fokwa

Keyword(s):

Density Functional ◽

Ternary Phase ◽

Structure Type ◽

X Ray Diffraction ◽

Functional Theory ◽

Arc Melting ◽

Ternary Boride ◽

Charge Analysis ◽

First Time ◽

Bader Charge Analysis

Abstract A new ternary phase, TiIrB, was synthesized by arc-melting of the elements and characterized by powder X-ray diffraction. The compound crystallizes in the orthorhombic Ti1+x Rh2−x+y Ir3−y B3 structure type, space group Pbam (no. 55) with the lattice parameters a = 8.655(2), b = 15.020(2), and c = 3.2271(4) Å. Density Functional Theory (DFT) calculations were carried out to understand the electronic structure, including a Bader charge analysis. The charge distribution of TiIrB in the Ti1+x Rh2−x+y Ir3−y B3-type phase has been evaluated for the first time, and the results indicate that more electron density is transferred to the boron atoms in the zigzag B4 units than to isolated boron atoms.

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Remarkable improvement in phosgene detection with a defect-engineered phosphorene sensor: first-principles calculations

Physical Chemistry Chemical Physics ◽

10.1039/d0cp00427h ◽

2020 ◽

Vol 22 (17) ◽

pp. 9677-9684 ◽

Cited By ~ 6

Author(s):

Mehdi Ghambarian ◽

Zahra Azizi ◽

Mohammad Ghashghaee

Keyword(s):

Density Functional Theory ◽

First Principles ◽

Density Functional ◽

First Principles Calculations ◽

Defect Engineering ◽

Functional Theory ◽

Remarkable Improvement ◽

Black Phosphorene ◽

First Time ◽

Theory Framework

A drastic improvement in the phosgene sensitivity of black phosphorene with defect engineering is reported for the first time within a periodic density functional theory framework.

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Crystal Structures of Al2Cu Revisited: Understanding Existing Phases and Exploring Other Potential Phases

Metals ◽

10.3390/met9101037 ◽

2019 ◽

Vol 9 (10) ◽

pp. 1037 ◽

Cited By ~ 4

Author(s):

Sai Wang ◽

Changzeng Fan

Keyword(s):

Crystal Structure ◽

High Pressure ◽

Single Crystal ◽

First Principles ◽

First Principles Calculations ◽

X Ray Diffraction ◽

X Ray ◽

Structural Relationships ◽

Al2cu Phase ◽

High Pressure Sintering

When processing single crystal X-ray diffraction datasets for twins of Al2Cu sample synthesized by the high-pressure sintering (HPS) method, we have clarified why the crystal structure of Al2Cu was incorrectly solved about a century ago. The structural relationships between all existing Al2Cu phases, including the Owen-, θ-, θ’-, and Ω-Al2Cu phases, were investigated and established based on a proposed pseudo Al2Cu phase. Two potential phases have been built up by adjusting the packing sequences of A/B layers of Al atoms that were inherent in all existing Al2Cu phases. The mechanical, thermal, and dynamical stability of two such novel phases and their electronic properties were investigated by first-principles calculations.

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