Title: Materials design, synthesis, and transport properties of disordered rare-earth Zintl bismuthides with the anti-Th₃P₄ structure type

Abstract

The synthesis, structural elucidation, and transport properties of the extended series Ca_4–xRE_xBi₃ (RE = Y, La–Nd, Sm, Gd–Tm, and Lu; x ≈ 1) and Ca_4–xRE_xBi_3–δSb_δ (RE = La, Ho, Er, and Lu; x ≈ 1, δ ≈ 1.5) are presented. Structural elucidation is based on single-crystal X-ray diffraction data and confirms the chemical drive of Ca4Bi3 with the cubic anti-Th₃P₄ structure type (space group I4 ¯3d, no. 220, Z = 4) into a Zintl phase by the introduction of trivalent rare-earth atoms. The structure features complex bonding, heavy elements, and electron count akin to that of valence-precise semiconductors, making it an ideal target for thermoelectrics development. Introducing crystallographic site disorders at the cation site for the Ca_4–xRE_xBi₃ phase and both the cation and anion sites for the Ca_4–xRE_xBi_3–δSb_δ phase brings about additional desirable characteristics for thermoelectric materials in the context of tuning knobs for lowering thermal conductivity. Electronic structure calculations of idealized Ca₃YBi₃ and Ca₃LaBi₃ compounds indicate the opening of indirect bandgaps at the Fermi level with magnitudes Eg = 0.38 eV and 0.57 eV, respectively. The electrical resistivity ρ(T) of some of the investigated phases measured on single crystals evolve in a metallic manner with magnitudes of order 1.4more » mΩ cm near 500 K, thus supporting the notion of a degenerate semiconducting state, with the temperature dependence of the Seebeck coefficient α(T) suggesting the p-type behavior. Furthermore, the low electrical resistivity and the realization of a degenerate semiconducting state in the title phases present a window of opportunity for optimizing their carrier concentrations for enhanced thermoelectric performance.« less

Authors:

Ogunbunmi, Michael O.  ^[1];

• Search DOE PAGES for author "Ogunbunmi, Michael O."
• Search DOE PAGES for ORCID "0000-0002-5340-9198"

Baranets, Sviatoslav  ^[1];

• Search DOE PAGES for author "Baranets, Sviatoslav"
• Search DOE PAGES for ORCID "0000-0003-3449-3344"

Bobev, Svilen  ^[1]

• Search DOE PAGES for author "Bobev, Svilen"
• Search DOE PAGES for ORCID "0000-0002-0780-4787"

---

+ Show Author Affiliations

1. Univ. of Delaware, Newark, DE (United States)

Publication Date:

Fri Mar 04 00:00:00 EST 2022

Research Org.:

Univ. of Delaware, Newark, DE (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1876204

Alternate Identifier(s):

OSTI ID: 1854654

Grant/Contract Number:  

SC0008885

Resource Type:

Accepted Manuscript

Journal Name:

Dalton Transactions

Additional Journal Information:

Journal Volume: 51; Journal Issue: 13; Journal ID: ISSN 1477-9226

Publisher:

Royal Society of Chemistry

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY