Computational Discovery of Promising New n-type Dopable ABX Zintl Thermoelectric Materials

<div> <div> <div> Computational prediction of good thermoelectric (TE) performance in several n-type doped Zintl phases, combined with successful experimental realization, has sparked interest in discovering new n-type dopable members of this family of materials. However, most known Zintls are typically only p-type dopable; prior successes in finding n-type Zintl phases have been largely serendipitous. Here, we go beyond previously synthesized Zintl phases and perform chemical substitutions in known n-type dopable ABX Zintl phases to discover new ones. We use first-principles calculations to predict their stability, potential for TE performance as well as their n-type dopability. Using this approach, we find 17 new ABX Zintl phases in the KSnSb structure type that are predicted to be stable. Several of these newly pre- dicted phases (KSnBi, RbSnBi, NaGeP) are predicted to exhibit promising n-type TE performance and are n-type dopable. We propose these compounds for further experimental studies, especially KSnBi and RbSnBi, which are both predicted to be good TE materials with high electron concentrations due to self-doping by native defects, when grown under alkali-rich conditions. </div> </div> </div>

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Computational Prediction and Experimental Realization of p-Type Carriers in the Wide-Band-Gap Oxide SrZn1–xLixO2

Inorganic Chemistry ◽

10.1021/acs.inorgchem.8b00697 ◽

2018 ◽

Vol 57 (19) ◽

pp. 11874-11883 ◽

Cited By ~ 2

Author(s):

Christos A. Tzitzeklis ◽

Jyoti K. Gupta ◽

Matthew S. Dyer ◽

Troy D. Manning ◽

Michael J. Pitcher ◽

...

Keyword(s):

Band Gap ◽

Wide Band ◽

Computational Prediction ◽

Wide Band Gap ◽

Experimental Realization ◽

P Type

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Hydrogen Donors in ZnO

MRS Proceedings ◽

10.1557/proc-864-e10.4 ◽

2005 ◽

Vol 864 ◽

Cited By ~ 3

Author(s):

M.D. McCluskey ◽

S.J. Jokela ◽

W.M. Hlaing Oo

Keyword(s):

First Principles ◽

Experimental Studies ◽

Shallow Donor ◽

Great Promise ◽

Bulk Single Crystal ◽

First Principles Calculations ◽

Electrical Measurements ◽

Hydrogen Donors ◽

Ir Signature ◽

P Type

AbstractZinc oxide (ZnO) has shown great promise as a wide-bandgap semiconductor with a range of optical, electronic, and mechanical applications. The presence of compensating donors, however, is a major roadblock to achieving p-type conductivity. Recent first-principles calculations and experimental studies have shown that hydrogen acts as a shallow donor in ZnO, in contrast to hydrogen's usual role as a passivating impurity. Given the omnipresence of hydrogen during growth and processing, it is important to determine the structure and stability of hydrogen donors in ZnO.To address these issues, we performed vibrational spectroscopy on bulk, single-crystal ZnO samples annealed in hydrogen (H2) or deuterium (D2) gas. Using infrared (IR) spectroscopy, we observed O-H and O-D stretch modes at 3326.3 cm-1 and 2470.3 cm-1 respectively, at a sample temperature of 10 K. These frequencies indicate that hydrogen forms a bond with a host oxygen atom, consistent with either an antibonding or bond-centered model. In the antibonding configuration, hydrogen attaches to a host oxygen and points away from the Zn-O bond. In the bond-centered configuration, hydrogen sits between the Zn and O. To discriminate between these two models, we measured the shift of the stretch-mode frequency as a function of hydrostatic pressure. By comparing with first-principles calculations, we conclude that the antibonding model is the correct one.Surprisingly, we found that the O-H complex is unstable at room temperature. After a few weeks, the peak intensity decreases substantially. It is possible that the hydrogen forms H2 molecules, which have essentially no IR signature. Electrical measurements show a corresponding decrease in electron concentration, which is consistent with the formation of neutral H2 molecules. The correlation between the electrical and spectroscopic measurements, however, is not perfect. We therefore speculate that there may be a second “hidden” hydrogen donor. One candidate for such a donor is a hydrogen-decorated oxygen vacancy.

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

10.26434/chemrxiv.13107566.v1 ◽

2020 ◽

Author(s):

Adam Balvanz ◽

Jiaxing Qu ◽

Sviatoslav Baranets ◽

Elif Ertekin ◽

Prashun Gorai ◽

...

Keyword(s):

First Principles ◽

Structure Type ◽

First Principles Calculations ◽

X Ray Diffraction ◽

Zintl Phases ◽

Band Engineering ◽

Isovalent Substitution ◽

Te Material ◽

First Time ◽

Complex Crystal

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

10.26434/chemrxiv.13107566 ◽

2020 ◽

Author(s):

Adam Balvanz ◽

Jiaxing Qu ◽

Sviatoslav Baranets ◽

Elif Ertekin ◽

Prashun Gorai ◽

...

Keyword(s):

First Principles ◽

Structure Type ◽

First Principles Calculations ◽

X Ray Diffraction ◽

Zintl Phases ◽

Band Engineering ◽

Isovalent Substitution ◽

Te Material ◽

First Time ◽

Complex Crystal

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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First-principles calculations to investigate mechanical, optoelectronic and thermoelectric properties of half-Heusler p-type semiconductor BaAgP

Results in Physics ◽

10.1016/j.rinp.2021.104068 ◽

2021 ◽

pp. 104068

Author(s):

F. Parvin ◽

M.A. Hossain ◽

I. Ahmed ◽

K. Akter ◽

A.K.M.A. Islam

Keyword(s):

Thermoelectric Properties ◽

First Principles ◽

First Principles Calculations ◽

Type Semiconductor ◽

P Type

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Structural and physical properties of 99 complex bulk chalcogenides crystals using first-principles calculations

Scientific Reports ◽

10.1038/s41598-021-89281-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sahib Hasan ◽

Khagendra Baral ◽

Neng Li ◽

Wai-Yim Ching

Keyword(s):

Mechanical Properties ◽

Physical Properties ◽

First Principles ◽

Experimental Studies ◽

First Principles Calculations ◽

Chalcogenide Semiconductors ◽

Optical And Mechanical Properties ◽

Very Large Database ◽

Unique Composition ◽

Fundamental Physical

AbstractChalcogenide semiconductors and glasses have many applications in the civil and military fields, especially in relation to their electronic, optical and mechanical properties for energy conversion and in enviormental materials. However, they are much less systemically studied and their fundamental physical properties for a large class chalcogenide semiconductors are rather scattered and incomplete. Here, we present a detailed study using well defined first-principles calculations on the electronic structure, interatomic bonding, optical, and mechanical properties for 99 bulk chalcogenides including thirteen of these crytals which have never been calculated. Due to their unique composition and structures, these 99 bulk chalcogenides are divided into two main groups. The first group contains 54 quaternary crystals with the structure composition (A2BCQ4) (A = Ag, Cu; B = Zn, Cd, Hg, Mg, Sr, Ba; C = Si, Ge, Sn; Q = S, Se, Te), while the second group contains scattered ternary and quaternary chalcogenide crystals with a more diverse composition (AxByCzQn) (A = Ag, Cu, Ba, Cs, Li, Tl, K, Lu, Sr; B = Zn, Cd, Hg, Al, Ga, In, P, As, La, Lu, Pb, Cu, Ag; C = Si, Ge, Sn, As, Sb, Bi, Zr, Hf, Ga, In; Q = S, Se, Te; $$\hbox {x} = 1$$ x = 1 , 2, 3; $$\hbox {y} = 0$$ y = 0 , 1, 2, 5; $$\hbox {z} = 0$$ z = 0 , 1, 2 and $$\hbox {n} = 3$$ n = 3 , 4, 5, 6, 9). Moreover, the total bond order density (TBOD) is used as a single quantum mechanical metric to characterize the internal cohesion of these crystals enabling us to correlate them with the calculated properties, especially their mechanical properties. This work provides a very large database for bulk chalcogenides crucial for the future theoretical and experimental studies, opening opportunities for study the properties and potential application of a wide variety of chalcogenides.

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Effect of native defects and Co doping on ferromagnetism in HfO2: First-principles calculations

Journal of Computational Chemistry ◽

10.1002/jcc.21711 ◽

2010 ◽

Vol 32 (7) ◽

pp. 1298-1302 ◽

Cited By ~ 3

Author(s):

Chong Han ◽

Shi-Shen Yan ◽

Xue-Ling Lin ◽

Shu-Jun Hu ◽

Ming-Wen Zhao ◽

...

Keyword(s):

First Principles ◽

First Principles Calculations ◽

Native Defects ◽

Co Doping

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Defect Complexes and Non-Equilibrium Processes Underlying the P-Type Doping of GaN

MRS Proceedings ◽

10.1557/proc-537-g5.3 ◽

1998 ◽

Vol 537 ◽

Author(s):

Fernando A. Reboredo ◽

Sokrates T. Pantelides

Keyword(s):

High Temperature ◽

Experimental Evidence ◽

First Principles ◽

Final Anneal ◽

First Principles Calculations ◽

Defect Complexes ◽

Equilibrium Processes ◽

Open Questions ◽

High Temperature Anneal ◽

P Type

AbstractIt is well known that hydrogen plays a key role in p-type doping of GaN. It is believed that H passivates substitutional Mg during growth by forming a Mgs-N-Hi complex; in subsequent annealing, H is removed, resulting in p-type doping. Several open questions have remained, however, such as experimental evidence for other complexes involving Mg and H and difficulties in accounting for the relatively high-temperature anneal needed to remove H. We present first principles calculations in terms of which we show that the doping process is in fact significantly more complex. In particular, interstitial Mg plays a major role in limiting p-type doping. Overall, several substitutional/interstitial complexes form and can bind H, with vibrational frequencies that account for hitherto unidentified observed lines. We predict that these defects, which limit doping efficiency, can be eliminated by annealing in an atmosphere of H and N prior to the final anneal that removes H.

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An effective and efficient approach to p-type AlN by Be2:O codoping from first-principles calculations

Modern Physics Letters B ◽

10.1142/s0217984916502572 ◽

2016 ◽

Vol 30 (20) ◽

pp. 1650257

Author(s):

Meng Zhao ◽

Wenjun Wang ◽

Jun Wang ◽

Junwei Yang ◽

Weijie Hu ◽

...

Keyword(s):

First Principles ◽

Ionization Energy ◽

Hole Concentration ◽

Valence Band Maximum ◽

First Principles Calculations ◽

Mutual Compensation ◽

Efficient Approach ◽

P Type ◽

Codoping Method

Various Be:O-codoped AlN crystals have been investigated via first-principles calculations to evaluate the role of the different combinations in effectively and efficiently inducing p-type carriers. It is found that the O atom is favored to bond with two Be atoms. The formed Be2:O complexes decrease the acceptor ionization energy to 0.11 eV, which is 0.16 eV lower than that of an isolated Be in AlN, implying that the hole concentration could probably be increased by 2–3 orders of magnitude. The electronic structure of Be2:O-codoped AlN shows that the lower ionization energy can be attributed to the interaction between Be and O. The Be–O complexes, despite failing to induce p-type carriers for the mutual compensation of Be and O, introduce new occupied states on the valence-band maximum (VBM) and hence the energy needed for the transition of electrons to the acceptor level is reduced. Thus, the Be2:O codoping method is expected to be an effective and efficient approach to realizing p-type AlN.

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