A simple method used for simultaneous measurement of phase retardation and optic axis of wave plate by employing 1/4 wave plate is demonstrated. The theoretical analysis of the measuring principle is presented in deta...A simple method used for simultaneous measurement of phase retardation and optic axis of wave plate by employing 1/4 wave plate is demonstrated. The theoretical analysis of the measuring principle is presented in detail. In the measurement, after adjusting a standard 1/4 wave plate and the fast (slow) axis of the plate to be measured parallel to the pass axis of the polarizer, the plate to be measured is rotated by 450 counterclockwisly. A stepping motor is used to rotate the analyzer. The experimental data are collected by a photodetector and then sent to a computer. According to the output data curve, the phase retardation and optic axis of the plate to be measured can be obtained simultaneously. To test the feasibility of the method, a λ /2 and a λ /8 wave plates are used as examples to demonstrate the measurement procedures. The phase retardation measurement accuracy is better than 0.5×10-2. This method can be used to measure the arbitrary phase retardation conveniently.展开更多
Silicon （Si） has the highest known theoretical specific capacity （3,590 mAh/g for Li1.5Si4, and 4,200 mAh/g for Li22Si4） as a lithium-ion battery anode, and has attracted extensive interest in the past few years. ...Silicon （Si） has the highest known theoretical specific capacity （3,590 mAh/g for Li1.5Si4, and 4,200 mAh/g for Li22Si4） as a lithium-ion battery anode, and has attracted extensive interest in the past few years. However, its application is limited by poor cyclability and early capacity fading due to significant volume changes during lithiation and delithiation processes. In this work, we report a coaxial silicon/anodic titanium oxide/silicon （Si-ATO--Si） nanotube array structure grown on a titanium substrate demonstrating excellent electrochemical cyclability. The ATO nanotube scaffold used for Si deposition has many desirable features, such as a rough surface for enhanced Si adhesion, and direct contact with the Ti substrate working as current collector. More importantly, our ATO scaffold provides a rather unique advantage in that Si can be loaded on both the inner and outer surfaces, and an inner pore can be retained to provide room for Si volume expansion. This coaxial structure shows a capacity above 1,500 mAh/g after 100 cycles, with less than 0.05% decay per cycle. Simulations show that this improved performance can be attributed to the lower stress induced on Si layers upon lithiation/delithiation compared with some other recently reported Si-based nanostructures.展开更多
文摘A simple method used for simultaneous measurement of phase retardation and optic axis of wave plate by employing 1/4 wave plate is demonstrated. The theoretical analysis of the measuring principle is presented in detail. In the measurement, after adjusting a standard 1/4 wave plate and the fast (slow) axis of the plate to be measured parallel to the pass axis of the polarizer, the plate to be measured is rotated by 450 counterclockwisly. A stepping motor is used to rotate the analyzer. The experimental data are collected by a photodetector and then sent to a computer. According to the output data curve, the phase retardation and optic axis of the plate to be measured can be obtained simultaneously. To test the feasibility of the method, a λ /2 and a λ /8 wave plates are used as examples to demonstrate the measurement procedures. The phase retardation measurement accuracy is better than 0.5×10-2. This method can be used to measure the arbitrary phase retardation conveniently.
文摘Silicon （Si） has the highest known theoretical specific capacity （3,590 mAh/g for Li1.5Si4, and 4,200 mAh/g for Li22Si4） as a lithium-ion battery anode, and has attracted extensive interest in the past few years. However, its application is limited by poor cyclability and early capacity fading due to significant volume changes during lithiation and delithiation processes. In this work, we report a coaxial silicon/anodic titanium oxide/silicon （Si-ATO--Si） nanotube array structure grown on a titanium substrate demonstrating excellent electrochemical cyclability. The ATO nanotube scaffold used for Si deposition has many desirable features, such as a rough surface for enhanced Si adhesion, and direct contact with the Ti substrate working as current collector. More importantly, our ATO scaffold provides a rather unique advantage in that Si can be loaded on both the inner and outer surfaces, and an inner pore can be retained to provide room for Si volume expansion. This coaxial structure shows a capacity above 1,500 mAh/g after 100 cycles, with less than 0.05% decay per cycle. Simulations show that this improved performance can be attributed to the lower stress induced on Si layers upon lithiation/delithiation compared with some other recently reported Si-based nanostructures.
