Effiziente direkte Wandlung von Wärme in Strom durch innovative Schichtstrukturen (LTEC)

• Unité de recherche: OFEN
• Numéro de projet: 102669

Mots-clé (Allemand)

TP0081;F-Elektrizitätstechnologien & -anwendung

Description succincte (Allemand)

Effiziente direkte Wandlung von Wärme in Strom durch innovative Schichtstrukturen (LTEC)

Publications / Résultats (Anglais)

CaMn0.98Nb0.02O2.98 single crystals were obtained by zone melting under pressure to avoid manganese evaporation. The phase purity, composition and structure of the crystal was analysed with X-ray diffraction (XRD). The crystal growth was affected by the rod’s quality, growth speed, atmosphere and pressure. Transmission electron microscopy (TEM) revealed structural intergrowth of CaMnO3 and CaMn2O4 and of CaMnO3 and CaMnO3-x that match quite well together in their lattices growth Finally, the Seebeck coefficient measured with a Physical Properties Measurement System (PPMS) was found to be higher than the calculated value. Our studies revealed the promising thermoelectric properties of CaMn0.98Nb0.02O3±δ with ZT1000K=0.32 and the contribution of twin domains to phonon scattering [3, 12]. The results contribute to a better understanding of the physical and chemical properties of manganese perovskite single crystals.

Auftragnehmer/Contractant/Contraente/Contractor:
EMPA

Autorschaft/Auteurs/Autori/Authors:
Alfaruq,Dimas Surya
Weidenkaff,Anke

Documents annexés

• Layered Thermoelectric Converters (LTEC) - Jahresbericht 2008 [PDF] 727 kB
• Efficient direct conversion of heat into electricity by innovative layered structures, Layered Thermoelectric Converters (LTEC) - Annual report 2009 [PDF] 329 kB
• Layered Thermoelectric Converters (LTEC) - Jahresbericht 2010 [PDF] 1'372 kB

Rapport final (Allemand)

CaMnO3 wurde in Form von polykristallinem Material, Filmen und Einkristallen hergestellt. Für die Synthese der Materialien wurde eine sogenannte „Soft Chemistry“-Methode verwendet. Zusätzlich wurde CaMnO3 mit kleinen Mengen Wolfram (1%, 3%, 5%) dotiert. Von allen hergestellten Verbindungen hatte CaMn0.97W0.03O3-δ den höchsten ZT-Wert und elektrischer Widerstand und Wärmeleitfähigkeit wurden erheblich verringert. Diese Ergebnisse sind darauf zurückzuführen, dass W eine höhere Anzahl an Elektronen in die CaMnO3-Struktur einbringt und somit eine effektivere Phononenstreuung bewirkt. Unsere Untersuchungen ergaben, dass die thermoelektrischen Eigenschaften der CaMnO3-Dünnfilme stark vom Syntheseweg abhängen. Mit Syntheseweg A wurden reinphasige CaMnO3-Dünnfilme mit höherer Ausgangsleistung und höherem elektrischem Widerstand erhalten als mit Syntheseweg B. Ein CaMn0.98Nb0.02O3-δ Einkristall wurde erfolgreich unter Anwendung der „Travelling Solvent Floating Zone“ (TSFZ)-Technik erzeugt. Bei der Untersuchung des Kristalles wurde eine reinphasige Region in der Kristallmitte identifiziert. Da der CaMn0.98Nb0.02O3-δ-Einkristall nahezu keine Korngrenzen besitzt, ist seine Wärmeleitfähigkeit verglichen mit polykristallinem CaMn0.98Nb0.02O3-δ bei einer Temperatur von 300 K höher.

Auftragnehmer/Contractant/Contraente/Contractor:
EMPA

Autorschaft/Auteurs/Autori/Authors:
Alfaruq,Dimas Surya
Weidenkaff,Anke

Rapport final (Anglais)

CaMnO3 was prepared in the form of polycrystalline material, films and single crystals. A soft chemistry method was chosen for the synthesis of the materials. In addition, CaMnO3 was substituted with small amounts of tungsten (1%, 3%, 5%). Of all the prepared compounds, CaMn0.97W0.03O3-δ had the highest ZT value and electrical resistivity, and the thermal conductivity was significantly reduced. This is due to the fact that W introduces more electrons into the CaMnO3 system and scatters phonons more efficiently. The thermoelectric properties of CaMnO3 thin films were found to depend strongly on the synthesis route. Route A yielded single-phase CaMnO3 thin films with higher output power and electrical resistivity than route B. A CaMn0.98Nb0.02O3-δ single crystal was successfully grown using the Travelling Solvent Floating Zone (TSFZ) technique. The characterization of the crystal revealed a single phase region in the center of the crystal. Due to the absence of grain boundaries, the thermal conductivity of the single crystal is higher compared to the polycrystalline sample at 300 K. Auftragnehmer/Contractant/Contraente/Contractor: EMPA Autorschaft/Auteurs/Autori/Authors: Alfaruq,Dimas Surya Weidenkaff,Anke

Documents annexés

• Layered Thermoelectric Converter (LTEC) - Final Report [PDF] 2'614 kB

CaMnO3 was prepared in the form of polycrystalline material, films and single crystals. A soft chemistry method was chosen for the synthesis of the materials. In addition, CaMnO3 was substituted with small amounts of tungsten (1%, 3%, 5%). Of all the prepared compounds, CaMn0.97W0.03O3-δ had the highest ZT value and electrical resistivity, and the thermal conductivity was significantly reduced. This is due to the fact that W introduces more electrons into the CaMnO3 system and scatters phonons more efficiently. The thermoelectric properties of CaMnO3 thin films were found to depend strongly on the synthesis route. Route A yielded single-phase CaMnO3 thin films with higher output power and electrical resistivity than route B. A CaMn0.98Nb0.02O3-δ single crystal was successfully grown using the Travelling Solvent Floating Zone (TSFZ) technique. The characterization of the crystal revealed a single phase region in the center of the crystal. Due to the absence of grain boundaries, the thermal conductivity of the single crystal is higher compared to the polycrystalline sample at 300 K.

Auftragnehmer/Contractant/Contraente/Contractor:
EMPA

Autorschaft/Auteurs/Autori/Authors:
Alfaruq,Dimas Surya
Weidenkaff,Anke