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- ItemTunable Pseudo-Piezoelectric Effect in Doped Calcium Titanate for Bone Tissue Engineering(Basel : MDPI, 2021) Riaz, Abdullah; Witte, Kerstin; Bodnar, Wiktor; Seitz, Hermann; Schell, Norbert; Springer, Armin; Burkel, EberhardCaTiO3 is a promising candidate as a pseudo-piezoelectric scaffold material for bone implantation. In this study, pure and magnesium/iron doped CaTiO3 are synthesized by sol-gel method and spark plasma sintering. Energy dispersive X-ray mapping confirm the homogenous distribution of doping elements in sintered samples. High-energy X-ray diffraction investigations reveal that doping of nanostructured CaTiO3 increased the strain and defects in the structure of CaTiO3 compared to the pure one. This led to a stronger pseudo-piezoelectric effect in the doped samples. The charge produced in magnesium doped CaTiO3 due to the direct piezoelectric effect is (2.9 ± 0.1) pC which was larger than the one produced in pure CaTiO3 (2.1 ± 0.3) pC, whereas the maximum charge was generated by iron doped CaTiO3 with (3.6 ± 0.2) pC. Therefore, the pseudo-piezoelectric behavior can be tuned by doping. This tuning of pseudo-piezoelectric response provides the possibility to systematically study the bone response using different piezoelectric strengths and possibly adjust for bone tissue engineering.
- ItemSuperconductivity in multi-phase Mg-B-O compounds(Amsterdam [u.a.] : Elsevier, 2012) Prikhna, T.; Gawalek, W.; Eisterer, M.; Weber, H.W.; Noudem, J.; Sokolovsky, V.; Chaud, X.; Moshchil, V.; Karpets, M.; Kovylaev, V.; Borimskiy, A.; Tkach, V.; Kozyrev, A.; Kuznietsov, R.; Dellith, J.; Shmidt, C.; Basyuk, T.; Litzkendorf, D.; Karau, F.; Dittrich, U.; Tomsic, M.Structures of MgB2-based materials manufactured under pressure (up to 2 GPa) by different methods having high superconducting performance and connectivity are multiphase and contain different Mg-B-O compounds. Some oxygen can be incorporated into MgB2 and boron into MgO structures, MgBx (X=4-20) inclusions contain practically no oxygen. Regulating manufacturing temperature, pressure, introducing additions one can influence oxygen and boron distribution in the materials and thus, affect the formation, amount and sizes of Mg-B-O and MgBx inclusions and changing type of pinning, pinning force and so affect critical current density jc. The boron concentration increase in initial Mg and B mixture allows obtaining sample containing 88.5 wt% of MgB12 with Tc of 37.4 K (estimated magnetically).
- ItemThermoelectric properties of silicon and recycled silicon sawing waste(Peking : Chinese Ceramic Society, 2019) He, R.; Heyn, W.; Thiel, F.; Pérez, N.; Damm, C.; Pohl, D.; Rellinghaus, B.; Reimann, C.; Beier, M.; Friedrich, J.; Zhu, H.; Ren, Z.; Nielsch, K.; Schierning, G.Large-scale-applicable thermoelectric materials should be both self-sustaining, in order to survive long-term duty cycles, and nonpolluting. Among all classes of known thermoelectric materials, these criteria reduce the available candidate pool, leaving silicon as one of the remaining options. Here we first review the thermoelectric properties of various silicon-related materials with respect to their morphologies and microstructures. We then report the thermoelectric properties of silicon sawing wastes recycled from silicon wafer manufacturing. We obtain a high power factor of ∼32 μW cm−1 K−2 at 1273 K with 6% phosphorus substitution in the Si crystal, a value comparable to that of phosphorus-doped silicon-germanium alloys. Our work suggests the large-scale thermoelectric applicability of recycled silicon that would otherwise contribute to the millions of tons of industrial waste produced by the semiconductor industry.