Qi Junjie

Abnormal magnetic behavior in DMS Zn1-xMnxO nanowires

Zn1−xMnxO nanowires were synthesized through chemical vapor deposition of pure Zn and MnCl2 power mixtures on silicon substrates. The morphology, structure and composition were measured by SEM, TEM, EDX and XRD. Magnetic properties were measured by SQUID. The results show that the nanowires exhibit clear ferromagnetic behavior at low temperature. An abnormal peak is observed in the M-T curve at 55 K in a magnetic field of 500 Oe.

Stretchable and multifunctional strain sensors based on 3D graphene foams for active and adaptive tactile imaging

The highly developed flexible electronics puts forward higher requirements for the stretchable strain sensors with excellent multiple performances. Herein, a simple and economical fabrication strategy is adopted to obtain a new strain sensor based on Ecoflex rubbers, three-dimensional (3D) graphene foams (GrF) and modified silicone rubber (MSR). The device possesses high stretchability (tolerable strain up to 100%) with a variety of capabilities, such as pressure and strain sensing, strain visualization and strain-controlled heating. The GrF with excellent electrical property and MSR with ideal mechanical property endow the sensor with a wide sensing range (up to 100% strain and 66 kPa stress), high sensitivity (gauge factor of 584.2 within the strain range of 80%–100% and sensitivity of 0.183 kPa−1 in 5–10 kPa) and long cycle life (more than 10,000 cycles) for pressure/strain sensing. In addition, the temperature of the device can be increased 35°C in 5 min under 5 V. Based on this, the deformation is visible to the naked eyes by the color conversion of thermochromic MSR. The soft and reversible strain sensor can be served as the electronic skin (e-skin) for real-time and high accuracy detecting of electrophysiological stimuli, a wearable heater for thermotherapy or body warming and even intelligent visual-touch panel.摘要柔性电子器件的高度发展使得人们对可拉伸应变传感器的综合性能及其多功能化提出了更高的要求. 本文采用一种简单、 经济的方法, 制备了一种基于橡胶、 三维石墨烯泡沫和改性硅橡胶的应变传感器. 该传感器具有高延展性和压力、 应变传感, 应变可视化以及焦耳加热等多种特性. 石墨烯泡沫优异的电学性能结合改性硅橡胶理想的机械性能使传感器具有较宽的传感范围(应变检测上限为100%, 应力检测上限为66 kPa)、 较高的灵敏度(最大应变灵敏度系数为584.2, 最大应力灵敏度系数为0.183 kPa−1)和较理想的使用寿命(循环拉伸次数超过10000个周期). 此外, 该传感器在5V的直流电压下5分钟内可加热35°C, 并可根据温致变色原理使器件的颜色随应变值发生人眼可见的往复变化, 从而实现应变的可视化. 该柔性多功能应变传感器可作为实时、 高精度检测物理刺激的电子皮肤, 热疗或保温的穿戴式加热器, 或可视化智能触摸面板.

Morphological effects on the field emission characteristics of zinc oxide nanotetrapods films

The direct growth of a tetrapod-like ZnO nanostructure has been accomplished by using a thermal oxidation method without any catalysts. Studies on the field emission properties of the ordered ZnO nanotetrapods films found that the shape of the ZnO nanotetrapods has considerable effect on their field emission properties, especially the turn-on field and the emission current density. Compared with the rod-like legs ZnO nanotetrapods, the nanotetrapods with acicular legs have a lower turn-on field of 2.7 V/μm at a current density of 10 μA/cm2, a high field enhancement factor of 1830, and an available stability. More importantly, the emission current density reached 1 mA/cm2 at a field of 4.8 V/μm without showing saturation. The results could be valuable for using the ZnO nanostructure as a cold-cathode field-emission material.