Journal of the Korean Ceramic Society

Abdelgawad, Mahmoud; El-Gamal, S. M. A.; Ewais, Emad M. M.; Li, Shufeng

doi: 10.1007/s43207-020-00095-0pmid: N/A

Fully cubic-stabilized zirconia ceramic composites have been successfully fabricated by conventional sintering technique using commercial monoclinic zirconia, Yttrium oxide and waste-derived magnesia-rich spinel (MMA) powder mixtures. In this study, effect of MMA content and sintering temperature on stabilization and densification properties of zirconia has been duly considered. The obtained results showed that m-ZrO2 in MMA-free Z0 reference specimen is partially stabilized upon temperature rising into tetragonal phase by Y3+ ions diffusion inside zirconia structure. MMA-free Z0 reference specimen sintered at 1600 ºC showed m- and t-ZrO2 dual-phase structure with a relative density of 80.2%. Unlike, upon rising the sintering temperature, Z10–Z50 composites containing 10–50 wt% MMA demonstrated higher relative density of more than 99% and showed variant behavior, where their m-ZrO2 is transformed and stabilized into cubic form by diffusion of Y3+, Mg2+ and Al3+ ions inside zirconia lattice structure. The outcomes indicate that MMA has significantly improved both the densification and stabilization behavior of m-ZrO2 through facilitating Y3+ diffusion inside zirconia lattice structure.

Noypha, Amnuay; Areerob, Yonrapach; Chanthai, Saksit; Nuengmatcha, Prawit

doi: 10.1007/s43207-020-00096-zpmid: N/A

In the present research work, Fe2O3-graphene-Ag (FGA) was synthesized by a simple hydrothermal method. The sonocatalytic activity of the FGA particles was evaluated by the degradation of methylene blue (MB) under ultrasonic irradiation, revealing their good sonocatalytic activity. The effects of various experimental factors, such as dosage, time, and ultrasonic frequencies on the sonocatalytic efficiency were investigated; a significant influence of different factors on the sonocatalytic degradation of MB was observed, whereas the best degradation conditions were obtained when ultrasonic irradiation was performed for 90 min at room temperature considering MB concentration = 0.5 g L−1, Ccatalyts = 1 g L−1, and pH 6.5. Moreover, the sonocatalytic activity of the FGA was compared to that of Fe2O3 (F), graphene (G), and Fe2O3-graphene (FG). As a result, the FGA was found to exhibit higher sonocatalytic activity than other catalysts (FGA > FG > G > F), which evidenced the practical utility of the synthesized FGA as a highly effective catalyst for the removal of dye pollutants. Finally, the plausible sonocatalytic mechanism of FGA is also discussed in this work.

Jerng, Sung Eun; Song, Junil; Cha, Kyoungjin; Ahn, Byungrok; Kim, Taesung; Lee, Jong Ho

doi: 10.1007/s43207-020-00101-5pmid: N/A

The uniform and continuous nickel internal electrode is crucial in high capacity and highly reliable multi-layer ceramic capacitors (MLCCs). However, the mechanism and the key factors that affect the roughness of the electrode have not been investigated thoroughly. Thus, seeking suitable descriptors that describe the most influential element which decides the roughness is required for the logical design of the Ni paste. In this study, we analyzed the surface of nickel powders and compared their electrode roughness in the aspects of the surface carbon species on nickel nanoparticles. As the increase in the relative C–O/C–C and C=O/C–C ratios, the relative electrode roughness of C-Ni-1, C-Ni-2, C-Ni-3, and C-Ni-4 increased from 1.00, 1.29, 1.54 to 2.51. Thus, low contents of C–O and C=O on the surface of Ni particles could improve the uniformity of the electrode. This study suggests a valuable perspective to reveal the decisive component to build the optimum surface of nickel nanoparticles for uniform internal electrodes in MLCCs.

Lamaiphan, Natthida; Sakaew, Chinawooth; Sricharoen, Phitchan; Nuengmatcha, Prawit; Chanthai, Saksit; Limchoowong, Nunticha

doi: 10.1007/s43207-020-00094-1pmid: N/A

The preparation and characterization of thiol-functionalized graphene oxide–iron oxide (Fe3O4–GO–SH) nanocomposites (novel magnetic adsorbents) for the simultaneous preconcentration and determination of heavy metal ions, such as Ag(I), Pb(II), and Cd(II), from water samples were carried out in the present research. The characterization of the resultant Fe3O4–GO–SH nanocomposites was performed by SEM, TEM, EDX, XRD, FT-IR, and VSM. The preconcentration optimization of pH solution, adsorbent amount, ultrasonic power for adsorption and desorption processes, adsorption time, and elution solvent type and concentration was performed by the ultrasonic-assisted magnetic solid-phase extraction. Under optimal conditions, linear ranges were found to be 20–1000 μg L–1 for Ag(I) and Cd(II) ions and 200–10,000 μg L–1 for Pb(II) ions with a regression coefficient of R2 > 0.99. The limits of detection for Ag, Pb, and Cd ions were 1.7 μg L–1, 14.1 μg L–1, and 0.9 μg L–1, respectively, and the limits of quantification for Ag, Pb, and Cd ions were 5.9 μg L–1, 47.3 μg L–1, and 3.2 μg L–1, respectively. The recovery rate of these metal ions for water samples (drinking water, tap water, swamp water, and wastewater from plating plants) ranged between 80 and 115%. Therefore, the proposed method can potentially be used for the simultaneous preconcentration and determination of heavy metal ions from real water samples, and its reusability can be easily carried out by the deionized water treatment.

Patel, Satyanarayan; Kodumudi Venkataraman, Lalitha; Yadav, Harekrishna

doi: 10.1007/s43207-020-00099-wpmid: N/A

BaTiO3-based derivatives have been explored in recent times for potential applications in energy harvesting and ultrasonics. To this end, energy harvesting and conversion applications require an understanding of the conduction and loss mechanisms. The conduction mechanism in Ba0.9Ca0.1TiO3 (BCT) ceramics is studied using impedance spectroscopy at different temperatures. Impedance analysis suggests the presence of two types of relaxation processes corresponding to grain and grain boundary contributions. The relaxation mechanism follows non-Debye-type behavior. The high resistance of the grain (bulk) in the ferroelectric region does not contribute to the high losses; the losses probably result from the phase transition. In addition, BCT ceramics exhibit a negative temperature coefficient of resistance (NTCR). The open-circuit pyroelectric voltage shows a twofold increase compared to (Ca, Zr) modification in BaTiO3.