Experimental and Theoretical Investigations for the Quaternary Mixed‐Cation Zintl Phase Ca1.82(1)Eu0.18CdSb2

Kim, Ki-Won; Jo, Hongil; Ok, Kang Min; You, Tae‐Soo

doi:10.1002/bkcs.11970

Cited by 7 publications

(3 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the other hand, the M1 and M2 sites contain only the Ca/Yb mixture (see Table 2). These particular site preferences of Ca and Yb in the Ca 5 Al 2 Bi 6 -type compounds can hardly be elucidated either by the size factor or electronic factor criteria 30,39 since the arc melting synthetic method is known to render cations to occupy the kinetically more favorable sites, just like the Ca 5−x Yb x Al 2 Sb 6 (1.0 ≤ x ≤ 5.0) 13 and CaYb 4 Al 2 Sb 6−x Ge x (x = 0.2, 0.5, 0.7) 14 systems. The noticeably distinctive feature of the current RE-doped Ca 5 Al 2 Bi 6 -type quinary system to the parental quaternary system 13 is that the kinetically favored site preferences of the cationic Ca and Yb cannot act as a driving force to trigger the "anticipated" phase transition from its initial phase to the Ca 5 Ga 2 As 6 -type phase despite the post-heat treatment process.…”

Section: ■ Introductionmentioning

confidence: 99%

p-Type to n-Type Conversion through the “Bypass” Phase Transition in the Zintl-Phase Thermoelectric Materials

Yeon

Sein

et al. 2021

Chem. Mater.

Self Cite

View full text Add to dashboard Cite

Six rare-earth (RE) metal-doped n-type Zintl-phase thermoelectric (TE) compounds in the Ca 5−x−y Yb x RE y Al 2 Sb 6 (RE = Pr, Nd, and Sm; 1.26 ≤ x ≤ 3.03; 0.15 ≤ y ≤ 0.45) system have been prepared using arc melting followed by the post-heat treatment, and the isotypic and homotypic crystal structures were carefully determined by the powder and single-crystal analyses. Six title compounds adopted either the Ca 5 Al 2 Bi 6 -type or Ca 5 Ga 2 As 6 -type phase in the orthorhombic Pbam space group (Z = 2, Pearson code oP26) with seven crystallographically independent atomic sites. Interestingly, the Yb-rich compounds originally crystallized in the Ca 5 Al 2 Bi 6 -type phase and maintained their structure type even after the post-heat treatment. On the other hand, the Ca-rich compounds with particular compositions adopted the Ca 5 Al 2 Bi 6 -type phase first and then underwent phase transition to the Ca 5 Ga 2 As 6 -type phase after the post-heat treatment at the high temperature. Moreover, this single-crystal to single-crystal phase transition also brought the p-type to n-type conversion of electrical transport property for the two Ca 5 Ga 2 As 6 -type title compoundsCa 3.46 Yb 1.35 Pr 0.19 Al 2 Sb 6 and Ca 3.30 Yb 1.50 Sm 0.20 Al 2 Sb 6 according to Seebeck coefficient measurements. As far as we understand, this study is the first example of producing novel n-type Zintl TE compounds by the "bypass" method through the p-type to n-type conversion of identical Zintl compounds in the A 5 M 2 Pn 6 (A = Ca, Sr, Eu, and Yb; M = Al, Ga, In; Pn = As, Sb, and Bi) system. Theoretical calculations conducted for the three hypothetical models rationalized the specific site preference of RE and the overall electronic structures. Hall effect measurements proved the n-type carrier, and the carrier concentration and carrier mobility of this Ca 5 Ga 2 As 6 -type Ca 3.46 Yb 1.35 Pr 0.19 Al 2 Sb 6 were also evaluated.

show abstract

Section: ■ Introductionmentioning

confidence: 99%

p-Type to n-Type Conversion through the “Bypass” Phase Transition in the Zintl-Phase Thermoelectric Materials

Yeon

Sein

et al. 2021

Chem. Mater.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Among the various TE materials, the Zintl phases that have intrinsically complex crystal structures and semiconducting behaviors are considered one of the most promising candidates for this application, and these include the A 14 MPn 11 (A = Ca, Yb; M = Mn, Al; Pn = Sb), , A 11 Pn 10 (A = Ca, Yb; Pn = Ge, Sb, Bi), − A 5 M 2 Pn 6 (A = Ca, Yb; M = Al, In; Pn = Sb, Sn), , and A 2 MPn 2 (A = Ca, Eu, Yb; M = Cd; Pn = Sb) systems. , In particular, worldwide research for the trigonal CaAl 2 Si 2 -type AM 2 Pn 2 (A = Ca, Sr, Ba, Eu, Yb; M = Zn, Cd; Pn = Sb) system has been recently conducted due to its relatively easy dopability and large ZT values. − On the other hand, despite the identical stoichiometry AM 2 Pn 2 , only a few compounds have been reported in the orthorhombic BaCu 2 S 2 -type AM 2 Pn 2 (A = Ba; M = Cu, Zn; Pn = Sb, Te) system for the TE application, such as the Ba 1– x – y Na x Sr y Zn 2 Sb 2 (0 ≤ x ≤ 0.1, 0 ≤ y ≤ 0.1) system, due to its narrow phase-width and limited dopability. − …”

Section: Introductionmentioning

confidence: 99%

Tuning the Radius Ratio to Enhance Thermoelectric Properties in the Zintl Compounds AM₂Sb₂ (A = Ba, Sr; M = Zn, Cd)

et al. 2023

Self Cite

View full text Add to dashboard Cite

Five novel Zintl phase solid solutions in the Ba1–x Sr x Zn2–y Cd y Sb2 (0 ≤ x ≤ 0.13(1); 0 ≤ y ≤ 0.32(2)) system were successfully synthesized by the molten Pb metal-flux method, and the powder X-ray diffraction and single-crystal X-ray diffraction analyses proved that all five title compounds adopted the BaCu2S2-type phase having the orthorhombic Pnma space group (Z = 4, Pearson code oP20) with five crystallographically independent atomic sites. The previously studied BaCu2S2-type antimonides demonstrated a limited tolerance for doping in contrast to the CaAl2Si2-type antimonides. To understand the relatively narrower phase width and limited dopability of the title BaCu2S2-type phase than the CaAl2Si2-type phase in the overall Ba1–x Sr x Zn2–y Cd y Sb2 system, the radius ratio of cations and anionic elements r +/r – for two structure types were thoroughly investigated. For the first time, the r +/r – ratio was identified as a critical factor for the phase selectivity: (1) r +/r – > 1 favored the BaCu2S2-type phase, and (2) r +/r – < 1 favored the CaAl2Si2-type phase. We also revealed the structural transformation mechanism from the more widely observed CaAl2Si2-type phase to the title BaCu2S2-type phase as the relatively larger cationic elements were introduced to the system. A series of DFT calculations using the three hypothetical models indicated that a resonance peak near E F in the density of states curves was descended from the relatively flat band structure at several special symmetry points rationalizing the enhanced Seebeck coefficients of Ba0.94(1)Sr0.06Zn1.86(3)Cd0.14Sb2 and Ba0.96(1)Sr0.04Zn1.68(2)Cd0.32Sb2. Electron localization function analysis rationalized the correlation between the polarity change of anionic Zn/Cd–Sb bonds and the charge carrier mobility on the anionic frameworks. Temperature-dependent thermoelectric properties were studied for the four title compounds, and the results proved that the Sr and Cd doping in the title Ba1–x Sr x Zn2–y Cd y Sb2 system successfully enhanced the ZT values through the increased Seebeck coefficients and the reduced total thermal conductivities.

show abstract

“…In particular, the Zintl phase containing the intrinsically semiconducting property with a small bandgap and exhibiting the low thermal conductivity due to the complex crystal structure has actively been investigated for the TE application 5,6 . Some examples of these Zintl phase TE materials include the Ca 2 − x RE x CdSb 2 (RE = Yb, Eu), 7–9 A 5 Al 2 Sb 6 (A = Ca, Yb), 10–12 Ca 11 − x RE x Sb 10 − y (RE = Tb, Dy, Ho, Er, Tm, Yb), 13,14 and A 14 MSb 11 (A = Ca, Yb; M = Mn, Al) systems 15–17 . Among the active worldwide investigations, we recently reported our research results for the n ‐type Ca 5 − x − y Yb x RE y Al 2 Sb 6 (RE = Pr, Nd, Sm) system showing the n ‐type electrical transport property by the successful addition of trivalent RE 3+ elements through the “ bypass ” method based on the phase‐transition from the Ca 5 Al 2 Bi 6 ‐type to the Ca 5 Ga 2 Sb 6 ‐type crystal structure 18 …”

Section: Introductionmentioning

confidence: 99%

Rare earth metal‐doped Zintl phase thermoelectric materials: The Yb₅₋_xRE_xAl₂Sb₆ (RE=Pr, Nd, Sm) system

Hong

Yeon

Jeong

et al. 2022

Bulletin Korean Chem Soc

Self Cite

View full text Add to dashboard Cite

Three Zintl phase solid solutions in the Yb 5 À x RE x Al 2 Sb 6 (RE = Pr, Nd, Sm) system have successfully been synthesized by arc melting followed by annealing. The isotypic crystal structure of these compounds was characterized by PXRD and SXRD analyses, and their Ca 5 Al 2 Bi 6 -type structure (space group Pbam, Z = 2) was described as a combination of (1) the 3-dimensional anionic [Al 2 (Sb 4 Sb 4/2 )] frameworks and (2) the space-filling cations Yb 2+ and RE 3+ located in between the anionic frameworks. In particular, the anionic frameworks were originally built from the two neighboring tetrahedral [AlSb 4 ] moieties via the Sb1-Sb1 bridges. The site-preference of RE 3+ for the Yb3/RE-site with the mixed occupation ratio between ca. 9% and 16% of RE 3+ was elucidated by the size-factor criterion based on the size match between the cationic size and the site volume. The band structures, density of states, and crystal orbital Hamilton population curve analyses were conducted by the tightbinding linear muffin-tin orbital method, and the results proved that the RE 3+doping increased the band degeneracies and the number of resonance peaks near the Fermi level resulting in the improved Seebeck coefficients. The electrical transport property measurements proved that despite the successful addition of n-type RE 3+ dopants in the title Yb 5 À x RE x Al 2 Sb 6 system, the electrical conductivity decreased due to the canceling off of the newly added n-type carriers by the already existing p-type carriers resulting in still the p-type character. However, the enhanced Seebeck coefficients predicted by the increased effective mass from the DFT calculations eventually improved the overall power factor of the RE 3+ -doped title compounds.

show abstract

Experimental and Theoretical Investigations for the Quaternary Mixed‐Cation Zintl Phase Ca_1.82(1)Eu_0.18CdSb₂

Cited by 7 publications

References 23 publications

p-Type to n-Type Conversion through the “Bypass” Phase Transition in the Zintl-Phase Thermoelectric Materials

p-Type to n-Type Conversion through the “Bypass” Phase Transition in the Zintl-Phase Thermoelectric Materials

Tuning the Radius Ratio to Enhance Thermoelectric Properties in the Zintl Compounds AM₂Sb₂ (A = Ba, Sr; M = Zn, Cd)

Rare earth metal‐doped Zintl phase thermoelectric materials: The Yb₅₋_xRE_xAl₂Sb₆ (RE=Pr, Nd, Sm) system

Contact Info

Product

Resources

About

Experimental and Theoretical Investigations for the Quaternary Mixed‐Cation Zintl Phase Ca1.82(1)Eu0.18CdSb2

Cited by 7 publications

References 23 publications

p-Type to n-Type Conversion through the “Bypass” Phase Transition in the Zintl-Phase Thermoelectric Materials

p-Type to n-Type Conversion through the “Bypass” Phase Transition in the Zintl-Phase Thermoelectric Materials

Tuning the Radius Ratio to Enhance Thermoelectric Properties in the Zintl Compounds AM2Sb2 (A = Ba, Sr; M = Zn, Cd)

Rare earth metal‐doped Zintl phase thermoelectric materials: The Yb5−xRExAl2Sb6 (RE=Pr, Nd, Sm) system

Contact Info

Product

Resources

About

Experimental and Theoretical Investigations for the Quaternary Mixed‐Cation Zintl Phase Ca_1.82(1)Eu_0.18CdSb₂

Tuning the Radius Ratio to Enhance Thermoelectric Properties in the Zintl Compounds AM₂Sb₂ (A = Ba, Sr; M = Zn, Cd)

Rare earth metal‐doped Zintl phase thermoelectric materials: The Yb₅₋_xRE_xAl₂Sb₆ (RE=Pr, Nd, Sm) system