Knight Shifts and Band Structure in the Lead-Salt Semiconductors

Senturia, S.D.; Smith, Alexis Nicole; Hewes, C.R.; Hofmann, J.; Sagalyn, Paul L.

doi:10.1103/physrevb.1.4045

Cited by 31 publications

(39 citation statements)

References 28 publications

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“…8d) for SnTe (x=1). This is an interesting result given that the SnTe is also a p-type semiconductor (with a lower Seebeck coefficient than PbTe) and this sort of temperature dependence is usually observed for n-type semiconductors, not p-type [12,13,[20][21][22][23][24][25][26] rates, see below). At this Sn fraction the CB and VB are now overlapped, yielding an increase in the DOS at the Fermi level and a metallic character due to the E g →0 (Fig.…”

Section: Temperature Dependence Of the Nmr Spectramentioning

confidence: 98%

“…Such a resonance frequency shift is considered large for a semiconductor. Previous studies have shown that the resonance shifts of 207 Pb can extend up to 12,000 ppm (relative to tetramethyllead [19,42] by extrapolating the resonance position to the limit of zero free carriers [12,21]. If the carrier concentration (Knight shift) were the main contribution to the total shift, then we should expect the 207 Pb spectrum of x=0.60 to be more upfield (lower frequency) than the spectrum of x=0.35.…”

Section: B Nmr Spectral Analysismentioning

confidence: 99%

“…even in samples that have identical band-edge properties. Clearly as shown above, there is sample variability but the presence of native defects and impurities play the key role in the correlation between the line broadening and conductivity, thus providing a reasonable explanation of the sample dependence on carrier density [21].…”

Section: B Nmr Spectral Analysismentioning

confidence: 99%

“…They can report on relativistic effects (such as SOC) related to heavy Z-elements in alloys [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Also, NMR can probe materials that are either p-type or ntype and also materials containing multiple fractions of different carrier types [12,13].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Site‐Specific Contributions to the Band Inversion in a Topological Crystalline Insulator

Koumoulis

Chasapis

Leung

et al. 2015

Adv Elect Materials

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Section: Temperature Dependence Of the Nmr Spectramentioning

confidence: 98%

Section: B Nmr Spectral Analysismentioning

confidence: 99%

Section: B Nmr Spectral Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Site‐Specific Contributions to the Band Inversion in a Topological Crystalline Insulator

Koumoulis

Chasapis

Leung

et al. 2015

Adv Elect Materials

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“…Although the results are affecte d by sample pre paration, for the bette r samples th e 207 Pb Kni ght s hift in n-type PbTe was found [156] to be te mperature independent, and relatively s mall and positive with res pect to undo pe d PbTe. On th e oth er hand in p-type, PbTe Jt(Pb) was found to be large, negative and temperature dependent.…”

Section: N (Ef)alloy = (L -C)na(ef )mentioning

confidence: 99%

Relevance of knight shift measurements to the electronic density of states

Bennett

Watson

Carter

1970

J. RES. NATL. BUR. STAN. SECT. A.

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The Knight shift, % , measures th e magne ti c hype rfin e fi eld at th e nucleu s produ ced by th e conducti on e lec tro ns whi c h are po la ri ze d in a ma gne ti c fi e ld. Kni ght s hifts are ofte n dominated by th e Pauli term a nd , in it.s mo st s impl e form , can be writte n as % = (a) x p. H ere XP is the conduction electron Pauli s pin s usce ptibility whic h de pe nd s on th e de nsity of states at th e Fe rmi le vel, N(EF), and (a ) is an a ve rage magneti c hype rfin e couplin g' cons tant associated with th e wav e function characte r at the nu c le us, 1

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Analysis of Phase Separation in High Performance PbTe–PbS Thermoelectric Materials

Girard

Schmidt‐Rohr

Chasapis

et al. 2012

Adv Funct Materials

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Phase immiscibility in PbTe–based thermoelectric materials is an effective means of top‐down synthesis of nanostructured composites exhibiting low lattice thermal conductivities. PbTe1‐x Sx thermoelectric materials can be synthesized as metastable solid solution alloys through rapid quenching. Subsequent post‐annealing induces phase separation at the nanometer scale, producing nanostructures that increase phonon scattering and reduce lattice thermal conductivity. However, there has yet to be any study investigating in detail the local chemical structure of both the solid solution and nanostructured variants of this material system. Herein, quenched and annealed (i.e., solid solution and phase‐separated) samples of PbTe–PbS are analyzed by in situ high‐resolution synchrotron powder X‐ray diffraction, solid‐state 125Te nuclear magnetic resonance (NMR), and infrared (IR) spectroscopy analysis. For high concentrations of PbS in PbTe, e.g., x >16%, NMR and IR analyses reveal that rapidly quenched samples exhibit incipient phase separation that is not detected by state‐of‐the‐art synchrotron X‐ray diffraction, providing an example of a PbTe thermoelectric “alloy” that is in fact phase inhomogeneous. Thermally‐induced PbS phase separation in PbTe–PbS occurs close to 200 °C for all compositions studied, and the solubility of the PbS phase in PbTe at elevated temperatures >500 °C is reported. The findings of this study suggest that there may be a large number of thermoelectric alloy systems that are phase inhomogeneous or nanostructured despite adherence to Vegard's Law of alloys, highlighting the importance of careful chemical characterization to differentiate between thermoelectric alloys and composites.

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Knight Shifts and Band Structure in the Lead-Salt Semiconductors

Cited by 31 publications

References 28 publications

Site‐Specific Contributions to the Band Inversion in a Topological Crystalline Insulator

Site‐Specific Contributions to the Band Inversion in a Topological Crystalline Insulator

Relevance of knight shift measurements to the electronic density of states

Analysis of Phase Separation in High Performance PbTe–PbS Thermoelectric Materials

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