Abstract
Poly-crystalline perovskite-type (CaLaMnO) Ca0.95La0.05Mn1−xNbxO3 (0.0≤x≤0.10) was synthesized using the conventional solid-state reaction method. Structural and morphological properties were studied by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM), respectively. Their transport and thermoelectric properties were studied from electrical resistivity ρ(T) and Seebeck coefficient S(T) measurements as a function of temperature and niobium content. The Rietveld analysis revealed a compound with orthorhombic structure, where their lattice parameters increase with the niobium content which is given by a distortion in octahedra MnO6. Electrical resistivity exhibits a semiconducting-like behavior, for low niobium contents (Nb≤0.03) the magnitude of the electrical resistivity decreases, reaching minimum values close to 0.1Ω− cm. Seebeck coefficient is negative in all studied temperature range. The temperature behavior of S(T) is interpreted in terms of variable range hopping (VRH ) and Heikes model. From ρ(T) and S(T) measurements it was possible to calculate the thermoelectric power factor (PF), which reaches maximum values around 0.4μW/K2-cm. These values make these ceramics promising electronic thermoelectric materials.
Published Version
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