Influence of nanometric microstructural development on thermophysical properties of lanthanum-doped strontium titanate

Idza Riati, Ibrahim and Khamirul Amin, Matori and Ismayadi, Ismail and Siti Nor Ain, Rusly and Rodziah, Nazlan and Nor Hidayat, Yusof and Mohd Hafiz, Mohd Zaid and Narong, Chanlek and Hideki, Nakajima and Norni Hidayawati, Mat Daud and Ghazaleh, Bahmanrokh (2021) Influence of nanometric microstructural development on thermophysical properties of lanthanum-doped strontium titanate. Materials Chemistry and Physics, 270 (124867).

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Abstract

The evolution of imperfect crystal from a highly amorphous structure to an ordered crystalline structure via sintering has demonstrated a significant development onto the thermophysical properties. Therefore, a series of La-doped strontium titanate with different morphological properties have been synthesized via high energy ball milling with subsequent sintering. Doping of lanthanum tends to inhibit the grain growth where a significant reduction of grain size (range from 34 nm to 0.47 μm) could be observed. A large amount of grain boundaries presence with fine grains, resulting from lanthanum doping, has enhanced phonon scattering, thus yielding a low heat propagation in La-doped SrTiO3. Besides acting as a grain growth inhibitor, lanthanum also acts as a scattering centre due to imperfection created by the doping. The scattering mechanisms significantly decrease the phonon mean free path. Consequently, the thermal diffusivity has been efficiently reduced to 1.1 mm2/s as compared to that of pure SrTiO3 which showed a value of about 3.8 mm2/s, both observed for the complete phase polycrystalline materials. The systematic development of thermophysical and morphological properties of La-doped SrTiO3 can be served as a preliminary guide to engineer thermoelectric materials with low thermal diffusivity.

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