홍성현 교수

Textured Nb‐doped bismuth titanate ceramics (Bi 4 Ti 3− x /5 ‐ Nb x /5 O 12 , where x = 0.02) were fabricated by templated grain growth. It was found that the use of a fine precursor powder led to enhanced densification of the ceramic, while Nb doping reduced electrical conduction and dielectric loss, which enabled poling at high temperatures and high electric fields. Sintered tapes showed anisotropic dielectric and piezoelectric properties when measured parallel and perpendicular to the casting

The silicon nanostructure is a promising candidate for an anode of Li-ion batteries due to its high theoretical capacity. In this work, we have demonstrated the scalable synthesis of Si nanosheets from natural sand by magnesiothermic reduction, and suggested a new formation mechanism for Si nanosheets. In the suggested mechanism, an Mg₂Si intermediate phase was formed at an early stage of the reduction process, which leads to the two-dimensional Si nanostructure. The synthesized Si nanosheets ha

Silver (or platinum)-containing calcium phosphate (hydroxyapatite (HA) and tricalcium phosphate (alpha-TCP)) coatings on titanium substrates were formed by micro-arc oxidation (MAO) and their in vitro antibacterial activity and in vitro cytotoxicity were evaluated. MAO was performed in an electrolytic solution containing beta-glycerophosphate disodium salt pentahydrate (beta-GP) and calcium acetate monohydrate (CA), and Ag and Pt were introduced in the form of AgNO(3) (or CH(3)COOAg) and H(2)PtC

SnO2@TiO2 double-shell nanotubes have been facilely synthesized by atomic layer deposition (ALD) using electrospun PAN nanofibers as templates. The double-shell nanotubes exhibited excellent high rate cyclability for lithium ion batteries. The retention of hollow structures during cycling was demonstrated.

Densification and anisotropic grain growth in diphasic‐gel‐derived, titania‐doped mullite were studied. Titania enhanced initial and intermediate stage densification in diphasic mullite gels by reducing the glass viscosity. Rodlike anisotropic mullite grains started to grow in titania‐doped diphasic mullite gels once a dense, equiaxed microstructure was achieved. The onset temperature for anisotropic grain growth decreased with increasing titania concentration because the sintering temperature f

Solid electrolytes, LiTi 2 (PO 4 ) 3 (LTP), Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP), and Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 2.9 (VO 4 ) 0.1 (LATPV), were prepared by conventional sintering (CS) and spark plasma sintering (SPS) methods, and the Li + ion conductivity of the sintered pellets was examined using an impedance analyzer. SPS remarkably improved the densification compared to CS and resulted in dense ceramics (95–97% of theoretical density) irrespective of the substituted ions. The highest conduc

Tin phosphide (Sn₄P₃) has emerged as an anode for sodium ion batteries (SIBs) due to its high reversible capacity and low redox potential.

Al‐doped CaCu 3 Ti 4− x Al x O 12− x /2 (CCTO, x =0–0.1) ceramics were prepared by the solid‐state reaction, and their electric and dielectric properties were investigated. Al doping has been shown to reduce the dielectric loss remarkably while maintaining a high dielectric constant. At x =0.06, the loss tangent (tan δ) was below 0.06 over the frequency range of 10 2 –10 4 Hz, and the dielectric constant was 41 000 at 10 kHz. Impedance spectra indicated that Al doping increased the resistivity o