Thermoelectric properties of CaMnO3 films obtained by soft chemistry synthesis

Polycrystalline randomly oriented CaMnO3 films were successfully deposited on sapphire substrates by soft chemistry methods. The precursor solutions were obtained from a mixture of metal acetates dissolved in acids. The Seebeck coefficient and the electrical resistivity were measured in the temperature range of 300 K < T < 1000 K. Modifications of thermal annealing procedures during the deposition of precursor layers resulted in different power factor values. Thermal annealing of CaMnO3 films at 900 °C for 48 h after four-layer depositions (route A) resulted in a pure perovskite phase with higher power factor and electrical resistivity than four-layer depositions of films annealed layer by layer at 900 °C for 48 h (route B). The studied films have negative Seebeck coefficients indicative of n-type conduction and electrical resistivities showing semiconducting behavio

High-temperature thermoelectric properties of W-substituted CaMnO 3

The thermoelectric properties of W-substituted CaMn1-xWxO3-δ (x = 0.01, 0.03; 0.05) samples, prepared by soft chemistry, were investigated from 300 K to 1000 K and compared to Nb-substituted CaMn0.98Nb0.02O3-δ. All compositions exhibit both an increase in absolute Seebeck coefficient and electrical resistivity with temperature. Moreover, compared to the Nb-substituted sample, the thermal conductivity of the W-substituted samples was strongly reduced. This reduction is attributed to the nearly two times greater mass of tungsten. Consequently, a ZT of 0.19 was found in CaMn0.97W0.03O3-δ at 1000 K, which was larger than ZT exhibited by the 2% Nb-doped sample.Fil: Alfaruq, Dimas S.. EMPA. Solid State Chemistry and Catalysis; SuizaFil: Eilertsen, James. EMPA. Solid State Chemistry and Catalysis; SuizaFil: Thiel, Philipp. EMPA. Solid State Chemistry and Catalysis; SuizaFil: Aguirre, Myriam H.. EMPA. Solid State Chemistry and Catalysis; SuizaFil: Otal, Eugenio Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Subsede Instituto Universitario Aeronáutico; ArgentinaFil: Populoh, Sascha. EMPA. Solid State Chemistry and Catalysis; SuizaFil: Yoon, Songhak. EMPA. Solid State Chemistry and Catalysis; SuizaFil: Weidenkaff, Anke. EMPA. Solid State Chemistry and Catalysis; Suiz

Crystal growth and thermoelectric properties of CaMn0.98Nb 0.02O3-δ

Thermoelectric CaMn0.98Nb0.02O3−δ single crystals were grown from sintered polycrystalline material using the traveling-solvent floating zone (TSFZ) method. The floating-zone furnace was operated at overpressure using an Ar/O2 mixture to prevent evaporation during the growth process. Six twin-domain variants were detected with single-crystal X-ray diffraction (XRD) and confirmed by electron diffraction (ED) and high-resolution transmission electron microscopy (HRTEM). The Seebeck coefficient (S) of the single-crystalline material indicates n-type semiconducting behavior. Within 10 KoTo125 K a negative peak in S is observed, known to be characteristic of antiferromagnetic ordering. The ferromagnetic longrange ordering, expected on the basis of double exchange between Mn4+ and doped Mn3+ species, thus appears to remain suppressed in the single-crystalline material.Fil: Alfaruq, Dimas S.. EMPA. Solid State Chemistry and Catalysis; SuizaFil: Aguirre, Myriam H.. EMPA. Solid State Chemistry and Catalysis; SuizaFil: Otal, Eugenio Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Subsede Instituto Universitario Aeronáutico; Argentina. Universidad Tecnológica Nacional. Facultad Regional Santa Cruz; ArgentinaFil: Populoh, S.. EMPA. Solid State Chemistry and Catalysis; SuizaFil: Karvonen, L.. EMPA. Solid State Chemistry and Catalysis; SuizaFil: Yoon, S.. EMPA. Solid State Chemistry and Catalysis; SuizaFil: Lu, Y.. EMPA. Solid State Chemistry and Catalysis; SuizaFil: Deng, G.. Paul Scherrer Institut. Solid State Chemistry Laboratory for Development and Methods; SuizaFil: Ebbinghaus, S. G.. Martin Luther Universität Halle-Wittenberg. Institut für Chemie; AlemaniaFil: Weidenkaff, A.. EMPA. Solid State Chemistry and Catalysis ; Suiz