SPS-assisted preparation of the Magnéli phase WO2.90 for thermoelectric applications

Kieslich, Gregor; Birkel, Christina S.; Douglas, Jason E.; Gaultois, Michael W.; Veremchuk, Igor; Seshadri, Ram; Stucky, Galen D.; Grin, Yuri; Tremel, Wolfgang

doi:10.1039/c3ta12145c

Cited by 23 publications

(28 citation statements)

References 32 publications

(36 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A local maximum at 635 K is in good accordance with previous records [11,12,24]. The electrical conductivity of WO2 and WO2.72 indicates typical metallic behaviour with σ(T) ∝ 1/T dependency ( Figure S1b).…”

Section: Thermoelectric Propertiessupporting

confidence: 76%

“…However, for WO 2.72 the approximation of κ lat shows uncertainty of maximum 45% and a significant difference regarding WO 3 cannot be determined. WO 2.90 shows κ tot ≈ 3.5-4.5 W·m −1 ·K −1 over the whole temperature range (Figure 6a), which is close to previously published values [11,24]. With respect to errors its lattice contribution κ lat equals that of WO 3 for T > 560 K (Figure 6b).…”

Section: Thermoelectric Propertiessupporting

confidence: 73%

“…Recently WO 2.72 (W 18 O 49 ) and WO 2.90 (W 20 O 58 ) were successfully prepared by spark plasma sintering (SPS) being promising bulk TE materials [11,12,24]. SPS combines the solid-state reaction of powdered precursor mixtures with simultaneous shaping, and provides an effective manufacturing route for TE materials due to low temperatures and short reaction times [8].…”

Section: Introductionmentioning

confidence: 99%

“…In the tungsten-oxygen system ( Figure 1a) with decreasing O/W-ratio x the observed phases are the insulating ReO 3 -type WO 3 , the semiconducting phase W 20 O 58 with CS planes, the metallic phase W 18 O 49 with pentagonal columns (PC) and the The vapor-transport preparation route to obtain these phases comprises a high-temperature heating of WOx powder mixtures over several days and weeks [14,15,[21][22][23]. Recently WO2.72 (W18O49) and WO2.90 (W20O58) were successfully prepared by spark plasma sintering (SPS) being promising bulk TE materials [11,12,24]. SPS combines the solid-state reaction of powdered precursor mixtures with simultaneous shaping, and provides an effective manufacturing route for TE materials due to low temperatures and short reaction times [8].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Spark Plasma Sintering of Tungsten Oxides WOx (2.50 ≤ x ≤ 3): Phase Analysis and Thermoelectric Properties

Kaiser¹,

Simon²,

Burkhardt³

et al. 2017

Crystals

Self Cite

View full text Add to dashboard Cite

Abstract:The solid-state reaction of WO 3 with W was studied in order to clarify the phase formation in the binary system W-O around the composition WO x (2.50 ≤ x ≤ 3) during spark plasma sintering (SPS). A new phase "WO 2.82 " is observed in the range 2.72 ≤ x ≤ 2.90 which might have the composition W 12 O 34 . The influence of the composition on the thermoelectric properties was investigated for 2.72 ≤ x ≤ 3. The Seebeck coefficient, electrical conductivity and electronic thermal conductivity are continuously tunable with the oxygen-to-tungsten ratio. The phase formation mainly affects the lattice thermal conductivity κ lat which is significantly reduced until 700 K for the sample with the composition x = 2.84, which contains the phases W 18 O 49 and "WO 2.82 ". In single-phase WO 2.90 and multi-phase WO x materials (2.90 ≤ x ≤ 3), which contain crystallographic shear plane phases, a similar reduced κ lat is observed only below 560 K and 550 K, respectively. Therefore, the composition range x < 2.90 in which the pentagonal column structural motif is formed might be more suitable for decreasing the lattice thermal conductivity at high temperatures.

show abstract

Section: Thermoelectric Propertiessupporting

confidence: 76%

Section: Thermoelectric Propertiessupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Spark Plasma Sintering of Tungsten Oxides WOx (2.50 ≤ x ≤ 3): Phase Analysis and Thermoelectric Properties

Kaiser¹,

Simon²,

Burkhardt³

et al. 2017

Crystals

Self Cite

View full text Add to dashboard Cite

show abstract

“…In previous studies SPS has been used to prepare single-phase W-containing oxides in a single step. 7,8 In contrast, when we employ a single step SPS process in this W-Nb-O system we observe multiple phases. BSE micrographs combined with EDX reveal the presence of W-rich inclusions with a wide range of length scales ( Figure 6).…”

Section: Resultsmentioning

confidence: 85%

Single-step preparation and consolidation of reduced early-transition-metal oxide/metal n-type thermoelectric composites

et al. 2015

Self Cite

View full text Add to dashboard Cite

Reduced early transition metal oxides/metal composites have been identified here as interesting thermoelectric materials. Numerous compositions in the Nb-rich portion of the WO3–Nb2O5 system have been studied, in composite formulations with elemental W. Spark plasma sintering (SPS) has been employed to achieve rapid preparation and consolidation of composite materials containing W metal precipitates with characteristic length scales that range from under 20 nm to a few microns, that exhibit thermal conductivities that are constant from 300 K to 1000 K, approximately 2.5 W m−1 K−1. Thermoelectric properties of these n-type materials were measured, and the highest-performing compositions were found to reach figure of merit zT values close to 0.1 at 950 K. The measurements point to higher zT values at yet-higher temperatures.

show abstract

Multiple‐Oxidation‐State Tungsten‐Oxide Clusters on a Carbon Surface as an Intersection between Molecular and Bulk Oxides

et al. 2021

View full text Add to dashboard Cite

Bulk tungsten oxides exhibit a wide range of oxidation states, whereas the oxidation states available in molecular oxides such as polyoxometalates (POMs) is limited. In this paper, tungsten oxide clusters with diameters of 1.2 � 0.4 (W 60 O x /C), 1.1 � 0.4 (W 28 O x /C), and 0.9 � 0.3 nm (W 12 O x /C) were produced in a sizeselective manner on graphitic carbon by using a phenylazomethine-type dendrimer as a template and applying hydrogen reduction after fixing the dendrimers on a support. X-ray photoelectron spectroscopy revealed that the W atoms in the clusters exhibited multiple oxidation states, i. e., W δ + , W 4 + , W 5 + , and W 6 +. Moreover, X-ray absorption fine structure measurements indicated the WÀ W bond length of 2.84-2.85 � 0.01 Å in these clusters. Auto-oxidation with adventitious oxygen after hydrogen reduction is proposed as a reasonable mechanism for the formation of these clusters on the carbon surface.

show abstract

SPS-assisted preparation of the Magnéli phase WO2.90 for thermoelectric applications

Cited by 23 publications

References 32 publications

Spark Plasma Sintering of Tungsten Oxides WOx (2.50 ≤ x ≤ 3): Phase Analysis and Thermoelectric Properties

Spark Plasma Sintering of Tungsten Oxides WOx (2.50 ≤ x ≤ 3): Phase Analysis and Thermoelectric Properties

Single-step preparation and consolidation of reduced early-transition-metal oxide/metal n-type thermoelectric composites

Multiple‐Oxidation‐State Tungsten‐Oxide Clusters on a Carbon Surface as an Intersection between Molecular and Bulk Oxides

Contact Info

Product

Resources

About