Congxu Zhu

Si-Coated Diamond Particles Reinforced Copper Composites Fabricated by Spark Plasma Sintering Process

This article introduced a unique production process of diamond/Cu composite materials via spark plasma sintering. Moreover, effects of Si-coated diamond particles and diamond volume fraction on heat conduction of diamond/Cu composite materials were examined. This research presented Si-coated diamond/Cu composite materials yielded higher heat conduction than that of the samples with uncoated diamond particles. It was found that Si-coated composite materials, including a volume fraction of 50% Si-coated diamond particles, yielded a relatively higher heat conduction of 535 W/mK along with the relative density of 96.3%. The phases present were identified by X-ray diffraction and microstructures were studied by scanning electron microscopy. Additionally, the influence of interface on heat conduction of diamond/Cu composites was specifically discussed.

Room-temperature magnetoelectric coupling study of multiferroic (1-x)(0.7BiFeO3-0.3Bi0.5Na0.5TiO3)-xCoFe2O4 ceramics

A series of (1−x)(0.7BiFeO3-0.3Bi0.5Na0.5TiO3)-xCoFe2O4 ceramics have been synthesized using the sol–gel method. Structural, microstructural, and multiferroic properties of the samples have been investigated. Magnetoelectric coupling has been also measured at room temperature. The structural and microstructural results show that perovskite 0.7BiFeO3-0.3Bi0.5Na0.5TiO3 and spinel CoFe2O4 can coexist in the ceramics without any observable impurities. The ceramics exhibit distinct ferromagnetic characteristics at room temperature. The dielectric constant and dielectric loss have been also studied as the function of frequency and temperature. The temperature dependence of dielectric properties displays a typical relaxor-like behavior at the temperature range of 150–300 °C. Due to magnetoelectric coupling, the dielectric anomaly at about 340 °C and the peak near 510 °C are respectively related to the ferroelectric transition of Bi0.5Na0.5TiO3 and magnetic transition of CoFe2O4. Impedance properties show the segment of arc at room temperature and the nearly perfect semicircle at higher temperature. Both Z′ and Z″ present regular change with the content of CoFe2O4. The room-temperature multiferroic properties of these new ceramics may be suitable for storage device applications.Graphical AbstractVariation of magnetoelectric coupling coefficient αE with the applied magnetic field.