Influence of soaking time on semi-conductivity and nonlinear electrical properties of TiO_2-based varistor ceramics

We investigated the influence of soaking time on the semi-conductivity and nonlinear electrical properties of TiO2- based varistor ceramic samples. We used a single sintering process and fabricated six disk samples of （Sr, Bi, Si, Ta）-doped TiO2- based varistor ceramics sintered at 1 250℃ for 0.5 h, 1.0 h, 2.0 h, 3.0 h, 4.0 h, and 5.0 h, respectively. The samples were characterized by X-ray diffraction, breakdown voltage, and complex impedance. The results show that as the soaking time increases from 0.5 h to 5.0 h, the breakdown voltage drops before rising while the nonlinear coefficient increases and then decreases. We suggest that, considering both grain semi-conductivity and nonlinear electrical properties of the TiO2-based varistor ceramics, the optimal soaking time is between 2.0 h and 3.0 h.

Organic-inorganic Hybrid Materials Based on Piperidine Derivatives and Semi-conductive Metal Iodine

Reactions of piperidine derivatives 4-(aminomethyl)piperidine(4-AMPD) and 1-methylpiperidin-4-amine(1-MPDA) with semi-conductive metal iodine SbI3 and PbI2 in concentrated HI aqueous solution afforded two one-dimensional(1 D) chain compounds [(4-AMPD)SbI5]n(1), [(1-MPDA)SbI5]n(2) and a two-dimensional(2 D) single layered organicinorganic hybrid material [(1-MPDA)PbI4]n(3), which were confirmed by X-ray single-crystal diffraction, infrared(IR) spectroscopy and powder X-ray diffraction(PXRD). Simultaneously, compounds 1~3 exhibit strong emission peaks at 600 nm for 1 and 2 and 570 nm for 3, which were originated from their inorganic moieties.

Dielectrophoretic assembly of semiconducting single-walled carbon nanotube transistor

A novel burning technique for making a semiconducting single-walled carbon nanotubes （SWNTs） transistor assembled by the dielectrophoretic force was suggested. The fabrication process consisted of two steps. First, to align and attach a bundle of SWNTs between the source and drain, the alternating （AC） voltage was applied to the electrodes. When a bundle of SWNTs was connected between two electrodes, some of metallic nanotubes and semi-conducing nanotubes existed together. The second step is to burn the metallic SWNTS by applying the voltage between two electrodes. With increasing the voltage, more current flowed through the metallic SWNTs, thus, the metallic SWNTs burnt earlier than the semiconducting one. This technique enables to obtain only semi-conducting SWNTs connection in the transistor. Through the 1--V characteristic graph, the moment of metallic SWNTs burning and the characteristic of semi-conducing nanotubes were verified.

Spin Transfer in EuO:Fe/GaAs Contact

Spin-wave structures whose current-voltage characteristics are controlled at room temperatures by magnetic field were produced with industrial technological methods using a spintronic europium-monoxide-based thin-film composite as an emitter and monocrystalline semiconductor n-GaAs as a collector. This shows that spin current transport actually exists and that a high-temperature spin transistor was produced with the use of the magnetic semiconductor/nonmagnetic semiconductor contact.

Fabrication of electrical semi-conductive SiCN ceramics by vat photopolymerization

The emergence of additive manufacturing(AM)enables ceramics to be fabricated with customized geometry,and polymer-derived ceramics(PDCs)has attracted growing attention owing to their irreplaceable advantages.The combination of 3D printing and PDCs endows the resultant ceramics with both precision and performance.However,AM of ceramics from preceramic polymers is still challenging,and insufficient investigation of functionality also limits the versatility of precursor and its derived ceramics.Herein,we propose a novel paradigm for 3D printing dense silicon carbonitride ceramic and study its electrical semiconducting properties.The formulated photosensitive precursor inks could achieve self-polymerization and cross-linking under the radiation of UV light(405 nm).The green body with intricate structures is fabricated by digital light processing(DLP).Lightweight(1.79-2.08 g cm^(-3))and low porosity(<5%)amorphous ceramics were obtained after thermal treatments.Processes of cross-linking,decomposition,and ceramization are monitored and analyzed.Furthermore,the semi-conducting behaviors of resultant ceramics are identified where the conductivity(10^(-5)-10^(-1)S m^(-1))has a monotonic correspondence with the testing temperatures(25-1000℃).The numerical relationship is fitted by exponential functions,and its conducting mechanism could be interpreted by the band tail hopping(BTH)model.This work could provide alternative solutions for the fabrication of PDCs and potentials for sensing applications.