Single crystal growth and magnetic properties of the mixed valent Yb containing Zintl phase, Yb<sub>14</sub>MgSb<sub>11</sub>

Wille, Elizabeth L. Kunz; Jo, Na Hyun; Fettinger, James C.; Canfield, Paul C.; Kauzlarich, Susan M.

doi:10.1039/c8cc05471a

Cited by 18 publications

(36 citation statements)

References 25 publications

(30 reference statements)

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“…The lower than expected carrier concentration by about 63% could be due to the experimental uncertainty of the Hall measurement or indicate the presence of a compensating Yb valence or intrinsic defect manifestation. Yb 14 MgSb 11 has been shown to contain Yb 3+ and intermediate valent Yb by x-ray absorption near-edge structure (XANES), magnetic, and heat capacity studies ( 35 , 36 ). Yb 14 ZnSb 11 , with the smallest unit cell reported to date and high carrier concentration, shows intermediate valent Yb ( 35 , 36 ).…”

Section: Resultsmentioning

confidence: 99%

“…Yb 14 MgSb 11 has been shown to contain Yb 3+ and intermediate valent Yb by x-ray absorption near-edge structure (XANES), magnetic, and heat capacity studies ( 35 , 36 ). Yb 14 ZnSb 11 , with the smallest unit cell reported to date and high carrier concentration, shows intermediate valent Yb ( 35 , 36 ). In the case of Yb 14 Mg 1− x Al x Sb 11 , the smaller unit cell and disorder added with the solid solution may initially increase the tendency for intermediate valency until the carrier concentration is diminished ( 25 , 36 , 37 ).…”

Section: Resultsmentioning

confidence: 99%

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Discovery of multivalley Fermi surface responsible for the high thermoelectric performance in Yb ₁₄ MnSb ₁₁ and Yb ₁₄ MgSb ₁₁

et al. 2021

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The Zintl phases, Yb14MSb11 (M = Mn, Mg, Al, Zn), are now some of the highest thermoelectric efficiency p-type materials with stability above 873 K. Yb14MnSb11 gained prominence as the first p-type thermoelectric material to double the efficiency of SiGe alloy, the heritage material in radioisotope thermoelectric generators used to power NASA’s deep space exploration. This study investigates the solid solution of Yb14Mg1−xAlxSb11 (0 ≤ x ≤ 1), which enables a full mapping of the metal-to-semiconductor transition. Using a combined theoretical and experimental approach, we show that a second, high valley degeneracy (Nv = 8) band is responsible for the groundbreaking performance of Yb14MSb11. This multiband understanding of the properties provides insight into other thermoelectric systems (La3−xTe4, SnTe, Ag9AlSe6, and Eu9CdSb9), and the model predicts that an increase in carrier concentration can lead to zT > 1.5 in Yb14MSb11 systems.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Discovery of multivalley Fermi surface responsible for the high thermoelectric performance in Yb ₁₄ MnSb ₁₁ and Yb ₁₄ MgSb ₁₁

et al. 2021

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“…Synthesis: The single crystals of Yb 14 MSb 11 were synthesized through previously reported flux methods [20,24,25]. The crystals were approximately 2 × 2 × 2 mm 3 in dimensions with highly reflective facets (see Supplemental Material Fig.…”

Section: Methodsmentioning

confidence: 99%

“…The predicted existence of Yb 3+ based on these simple electron counting rules is confirmed through magnetization measurements on single crystal samples. An effective magnetic moment of μ eff = 3.8 μ B /fu (fu = formula unit) for T > 150 K is observed for the Zn analog [24] and a μ eff = 3.4 μ B /fu for the Mg analog [25] suggesting intermediate Yb valence states (Yb 3+ ( f 13 , J = 7/2) has μ eff = 4.54 μ B ). This hypothesis has been supported through XPS where both Yb 2+ and Yb 3+ have been observed for the Zn analog [22].…”

Section: Introductionmentioning

confidence: 99%

Symmetric Bloch oscillations of matter waves

et al. 2020

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Yb 14 MnSb 11 is a magnetic Zintl compound as well as being one of the best high temperature p-type thermoelectric materials. According to the Zintl formalism, which defines intermetallic phases where cations and anions are valence satisfied, this structure type is nominally made up of 14 Yb 2+ , 1 MnSb 9− 4 , 1 Sb 7− 3 , and 4 Sb 3− atoms. When Mn is replaced by Mg or Zn, the Zintl defined motifs become 13 Yb 2+ , 1 Yb 3+ , 1 (Mg, Zn)Sb 10− 4 , 1 Sb 7− 3 , and 4 Sb 3− . The predicted existence of Yb 3+ based on simple electron counting rules of the Zintl formalism calls the Yb valence of these compounds into question. X-ray absorption near-edge structure, magnetic susceptibility, and specific heat measurements on single crystals of the three analogs show signatures of intermediate valence Yb behavior and in particular, reveal the heavy fermion nature of Yb 14 MgSb 11 .Inthese isostructural compounds, Yb can exhibit a variety of electronic configurations from intermediate (M = Zn), mostly 2+ (M = Mn), to 3+ (M = Mg). In all cases, there is a small amount of intermediate valency at the lowest temperatures. The amount of intermediate valency is constant for M = Mn, Mg and temperature dependent for M = Zn. The evolution of the Yb valence correlated to the transport properties of these phases is highlighted. The presence of Yb in this structure type allows for fine tuning of the carrier concentration and thereby the possibility of optimized thermoelectric properties along with unique magnetic phenomena.

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“…The existence of 0.75 Yb 3+ in this compound makes Yb 14 ZnSb 11 close to a valence precise Zintl formula, but the low resistivity and intermediate valence of Yb distinguish it from this simplistic interpretation of bonding. Recently, magnetic susceptibility measurements of the Mg compound were reported and are consistent with a similar amount of Yb 3+ , but there is no evidence for intermediate valency [11]. Yb 14 MnSb 11 contains only Yb 2+ , confirmed by X-ray photoelectron spectroscopy (XPS) and X-ray magnetic circular dichroism (XMCD) and neutron measurements [8,12].…”

Section: Introductionmentioning

confidence: 94%

Seebeck and Figure of Merit Enhancement by Rare Earth Doping in Yb14-xRExZnSb11 (x = 0.5)

et al. 2019

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Yb14ZnSb11 has been of interest for its intermediate valency and possible Kondo designation. It is one of the few transition metal compounds of the Ca14AlSb11 structure type that show metallic behavior. While the solid solution of Yb14Mn1-xZnxSb11 shows an improvement in the high temperature figure of merit of about 10% over Yb14MnSb11, there has been no investigation of optimization of the Zn containing phase. In an effort to expand the possible high temperature p-type thermoelectric materials with this structure type, the rare earth (RE) containing solid solution Yb14-xRExZnSb11 (RE = Y, La) was investigated. The substitution of a small amount of 3+ rare earth (RE) for Yb2+ was employed as a means of optimizing Yb14MnSb11 for use as a thermoelectric material. Yb14ZnSb11 is considered an intermediate valence Kondo system where some percentage of the Yb is formally 3+ and undergoes a reduction to 2+ at ~85 K. The substitution of a 3+ RE element could either replace the Yb3+ or add to the total amount of 3+ RE and provides changes to the electronic states. RE = Y, La were chosen as they represent the two extremes in size as substitutions for Yb: a similar and much larger size RE, respectively, compared with Yb3+. The composition x = 0.5 was chosen as that is the typical amount of RE element that can be substituted into Yb14MnSb11. These two new RE containing compositions show a significant improvement in Seebeck while decreasing thermal conductivity. The addition of RE increases the melting point of Yb14ZnSb11 so that the transport data from 300 K to 1275 K can be collected. The figure of merit is increased five times over that of Yb14ZnSb11 and provides a zT ~0.7 at 1275 K.

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Single crystal growth and magnetic properties of the mixed valent Yb containing Zintl phase, Yb₁₄MgSb₁₁

Abstract: Large crystals of Yb14MgSb11 prepared by Sn flux show the presence of Yb3+ making this compound a Zintl phase.

Cited by 18 publications

References 25 publications

Discovery of multivalley Fermi surface responsible for the high thermoelectric performance in Yb ₁₄ MnSb ₁₁ and Yb ₁₄ MgSb ₁₁

Discovery of multivalley Fermi surface responsible for the high thermoelectric performance in Yb ₁₄ MnSb ₁₁ and Yb ₁₄ MgSb ₁₁

Symmetric Bloch oscillations of matter waves

Seebeck and Figure of Merit Enhancement by Rare Earth Doping in Yb14-xRExZnSb11 (x = 0.5)

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Single crystal growth and magnetic properties of the mixed valent Yb containing Zintl phase, Yb14MgSb11

Abstract: Large crystals of Yb14MgSb11 prepared by Sn flux show the presence of Yb3+ making this compound a Zintl phase.

Cited by 18 publications

References 25 publications

Discovery of multivalley Fermi surface responsible for the high thermoelectric performance in Yb 14 MnSb 11 and Yb 14 MgSb 11

Discovery of multivalley Fermi surface responsible for the high thermoelectric performance in Yb 14 MnSb 11 and Yb 14 MgSb 11

Symmetric Bloch oscillations of matter waves

Seebeck and Figure of Merit Enhancement by Rare Earth Doping in Yb14-xRExZnSb11 (x = 0.5)

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Single crystal growth and magnetic properties of the mixed valent Yb containing Zintl phase, Yb₁₄MgSb₁₁

Discovery of multivalley Fermi surface responsible for the high thermoelectric performance in Yb ₁₄ MnSb ₁₁ and Yb ₁₄ MgSb ₁₁

Discovery of multivalley Fermi surface responsible for the high thermoelectric performance in Yb ₁₄ MnSb ₁₁ and Yb ₁₄ MgSb ₁₁