Electrical properties of polylactic acid with nucleating agent added

We examined the electrical properties of polylactic acid (PLA) with a nucleating agent added. The PLA with added nucleating agent was then heat‐treated at 100 °C for 30 seconds. The crystallinity of the PLA with added nucleating agent increased to more than 40%, and its crystallization speed also increased significantly. The temperature dependence of the conductivity (σ) was investigated; at temperatures higher than 60 °C, σ of PLA to which the nucleating agent had been added showed a tendency to become lower than σ of PLA to which no nucleating agent had been added. The temperature dependence of the dielectric breakdown strength ( ) was investigated. of the PLA with added nucleating agent was about 5.0 MV/cm at 25 °C. Of particular note was the fact that the of PLA with added nucleating agent was about 4.7 MV/cm at 100 °C, which is about 3 times the value for PLA with no added nucleating agent. The temperature dependence of the relative dielectric constant (?_r^″) and the relative dielectric loss factor (?_r^″) was investigated. The peak dielectric absorption value of ?_r^″ for the PLA to which nucleating agent had been added showed a tendency to be lower than that of the PLA to which no nucleating agent had been added. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(3): 25–31, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21293     

Dielectric breakdown and mechanical properties of polylactic acid of different spherulite sizes

The degree of crystallinity of polylactic acid (PLA) was increased by heat treatment, and the dielectric breakdown strength and mechanical properties of the obtained PLA of different spherulite sizes were studied. PLA heat‐treated at a temperature of 120 °C or higher showed rapid increases in spherulite size. At both measurement temperatures of 25 and 80 °C, the dielectric breakdown strength (E_B) showed rapid reduction. The tensile strength at break and breaking elongation showed rapid reduction when the heat treatment temperature was 120 °C or higher. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Dielectric breakdown properties of polylactic acid with β‐crystalline chitin

β‐Crystalline chitin was added to polylactic acid (PLA), and this PLA was then heat treated at 100 °C for 1 min. The crystallinity of the heat‐treated PLA increased to more than 40%, and its crystallization speed also increased significantly. Furthermore, the temperature dependence of the dielectric breakdown strength (E_B) was checked, and it was found that at a temperature of 80 °C, the E_B value of the PLA with chitin was around 1.8 times greater than that of the PLA without chitin. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Electrical properties of meridians

An overview of the electrodermal screening test is given. An existing model of the electrical properties of the skin has been the accepted scientific standard for decades. But this model is based entirely on mechanistic principles and it fails to explain many biological phenomena, particularly those relating to acupuncture points and meridians. The author has developed a new model which, unlike the standard model, includes an active biological response and the fact that the electricity passes though different types of tissue, not just skin. This model not only explains much of acupuncture phenomena, in general, but can also be used to explain all possible EDST readings. The author has reviewed studies of electrodermal properties with studies of qualities specific to meridians. The author discovered that meridians have higher conductance, faster electromagnetic wave propagation, and patterns of preferential direction. Because of these factors, the meridian system acts as a particularly good network for the communication of bioinformation and thus plays an essential role in biological function. It is very interesting that much of what has been learned through studies using the most modern equipment and methodologies is in agreement with meridian theory dating from 100 B.C.E. and earlier     

Electrical properties of chemically modified polyethylenes

This report describes electrical properties such as space charge distribution, water treeing characteristics and ac breakdown strength in PE (polyethylene) modified by grafting and blending techniques. A control PE shows heterocharge. In AA (acrylic acid)-grafted PE (LDPE-g-AA), the heterocharge observed in PE decreases at low AA contents and homocharge is observed at high AA contents. In NBA (n-butyl acrylate)-grafted PE (LDPE-g-NBA), on the other hand, this heterocharge gets larger at all graft ratios to 0.12%. However, these components decrease the water tree length measured under specific conditions and increase ac breakdown strength. Details of the results are described and their origins are discussed. The results obtained with the LDPE-g-NBA are compared with those of PE/ethylene NBA copolymer blends     

聚苯胺膜电极的电化学性能

CS-PAn(化学氧化聚合法合成聚苯胺)膜电极的CV曲线类似于ES-PAn(电化学聚合法合成的聚苯胺)膜电极,而且他们都具有优良的可逆性和循环稳定性。交流阻抗图谱表明两种方法制备的PAn具有相同的电化学反应机理。C S-PAn-Li和ES-PAn-Li扣式电池的最大放电比容量分别为75m Ah.g-1和86m Ah.g-1,容量衰减率分别为13.2%和6.8%,ES-PAn-Li扣式电池的大电流充放电性能优于CS-PAn-Li扣式电池。     

Electrical properties of Pb(Zr0.53Ti0.47)O3 thin film capacitors with modified RuO2 bottom electrodes

Abstract

Growth of Pb(Zr_0.53Ti_0.47)O₃ (PZT) thin films on RuO₂ electrodes by the sol-gel process is usually accompanied by the formation of second phases. The resulting RuO₂/PZT/RuO₂ capacitors are fatigue-free up to nearly 10¹¹ switching cycles, but they have high leakage currents (J～10^?3 A/cm² at 1 volt) and large property variation. We have developed several modifications of the RuO₂ bottom electrode which enhance nucleation of the perovskite phase, eliminate or reduce the second phases, and control film orientation and properties. The PZT films deposited on the modified RuO₂ electrodes have leakage current densities which are two to four orders of magnitude lower than those of PZT films deposited on the unmodified RuO₂ electrodes. In most cases, the excellent resistance to polarization fatigue which is characteristic of the RuO₂/PZT/RuO₂ capacitors, is maintained.     

电光聚合物薄膜传感器及其电光性能*

为了获得更高的电光系数,提升电光性能的同时又能兼备良好的热稳定性和相容性,以电光聚合物材料为主体,通过化学与物理相结合的方法,制备了两种新型双电光分子聚合物传感器。测试了传感器的电光性能,实验研究了掺杂比、极化温度对器件电光系数的影响。分析可知,电光系数随着掺杂比例的增加而变大,但是如果掺杂比例过高,电光系数随着掺杂比例的增加而减小。这是由于过高的掺杂比降低了聚合物的玻璃化温度,导致相分离现象在极化过程中发生。对传感器进行了取向排列稳定性测试,结果表明,介电弛豫在中仍然存在。然而由于电光聚合物自身具有较大电光系数,即使在介电弛豫出现后,仍然可以表现出较强的电光特性,是一种高效电光传感器件。     

铅钙合金阳极膜的性能研究

利用阳极极化曲线和交流阻抗技术,研究了Pb-Ca-Sn-Ce合金与Pb-Ca-Sn合金的耐腐蚀性能;用XPS研究了不同合金在0.9 V下腐蚀6h所形成的阳极腐蚀膜.结果表明Pb-Ca-Sn-Ce合金的耐腐蚀性能优于Pb-Ca-Sn合金,其阳极腐蚀膜主要由导电性良好的PbO2组成,说明Pb-Ca-Sn-Ce合金可以改善铅酸电池的深循环性能.     

Electrical properties of PZT piezoelectric ceramic at high temperatures

Advanced aeronautic and space structures need active components that can function at high frequencies and temperatures. Piezoelectric materials can provide frequency response but their use at elevated temperatures is limited. The reason for the lack of insertion of piezoelectric for high temperature active component and sensors are two fold. First, the database of piezoelectric properties that describe the piezoelectric constants is lacking for high temperatures engineering applications. Most studies measure the dielectric constants to determine the Curie temperature but do not provide piezoelectric coefficients as a function of temperature. Second, piezoelectric materials with Curie temperature (T _C) exceeding 500 °C are sought for aeronautics and aerospace applications. This investigation describes a measurement system that captures the impedance dependence upon temperature for piezoelectric materials. Commercially available lead zirconate titanate (PZT) was studied as to determine the piezoelectric activity to define the operating envelope with respect to temperature. The elastic properties , piezoelectric coefficients , dielectric properties , and electro-mechanical coupling factors were determined as a function of temperature. The coupling factor k ₃₃ was found to be relatively constant to 200 °C and exhibit slight temperature dependence above 200 °C. The temperature sensitivity for both piezoelectric coefficient and electromechanical coupling factor were very small; the slopes and Δk ₃₃/k ₃₃ were found to be 0.01 and (−0.07) respectively in the range of 120 to 200 °C. This measurement technique will populate databases that describe the piezoelectric properties of commercially available PZT piezoelectric materials. It can also facilitate the assessment of new piezoelectric materials that are currently being developed for higher temperature applications. This work is supported by US Air Force grant F49620-03-1-0128.     

Electromechanical modeling and properties of the electret film EMFI

An electromechanical film can be manufactured with different thickness and elasticity. The thickness for sensor and actuator applications is typically between 30 and 70 μm. The film is modeled using a simplified structure, which shows the reciprocity of the sensor and actuator operation models. The value of the transducer constant depends on the ambient temperature and increases at higher temperatures. During aging the transducer constant begins to decrease permanently at 323 K, but some sensitivity remains even at 333 K. Corona charging that gives a sensitivity value ~200 pCN^-1 for HS01 type film is preferred over electron beam charging. The development of such films is aimed at sensor and actuator applications. An interesting field is the active control of sound where flat and efficient microphones and loudspeakers are needed     

Electrical properties of hydrocarbon‐derived electrolytes for supercapacitors

The paper evaluates the essential electrical properties—capacitance and equivalent series resistance (ESR)—of hydrocarbon‐derived electrolytes for supercapacitors using galvanostatic, constant resistance charge–discharge, cyclic voltammetry, and AC impedance measurements. The electrolytes were systematically prepared from six hydrocarbon‐derived compounds, which have different carbon chains and functional groups, with the treatment of concentrated sulfuric acid (H₂SO₄). Both electrical properties seem to be in conformity throughout these measurements, with the longer main carbon chain compounds giving higher capacitance and lower ESR values. Comparison between these electrolytes and the typically used aqueous solutions in supercapacitor research—1M H₂SO₄, 5M potassium hydroxide, and 5M sodium hydroxide—showed that the produced electrolytes give the highest capacitance value up to 30 times more than that of typical aqueous solutions. It is believed that with further treatment these hydrocarbon‐derived electrolytes can potentially be used in supercapacitors as better performing electrolytes than aqueous solutions and at a relatively low cost compared to organic solutions. IEEJ Trans 2011 DOI: 10.1002/tee.21802     

Electrical properties of sol-gel derived La-doped PbTiO3-containing films

Abstract

A series of sol-gel derived La-doped PbTiO₃-containing films was prepared on platinized Si wafers. The compositions investigated include PLT (0-28 mole % La) and PLZT (e.g., 9/65/35 and 12/80/20) films. These films were fired at temperatures ranging from 500 to 750°C. While most of the films were single-phase perovskite when fired at 700°C, lower firing temperatures (～500°C) are sufficient to obtain crystalline PLT films, especially when the La content is more than 15 mole %. The paraelectric or ferroelectric character of the films as a function of La content is also addressed. In PLZT films, the Zr/Ti ratio affects the crystallization behavior and also the perovskite structure, i.e., either tetragonal or rhombohedral. Ferroelectric PLZT films exhibit high values of both dielectric constant (>700) and leakage current. The values of dielectric constant in the relaxor PLZT films are low, especially when compared to their bulk ceramic values (5000–10000). Paraelectric PLT films exhibit high values of dielectric constant (>500) and low leakage currents.     

Electrical and optical properties of metal-insulator-transition VO2 thin films

Vanadium dioxide thin films were deposited using in situ pulsed laser deposition technique on a-, c-, and r-plane Al₂O_3, and MgO(100) substrates. Microstructure of the films was varied between epitaxial VO₂, polycrystalline VO₂, mixtures of VO₂ and V₆O₁₃ with VO₂ as the main phase, and mixtures of VO₂ and V₆O₁₃ with V₆O₁₃ as the main phase by controlling the deposition oxygen partial pressure. Detailed XRD, SPM, and FESEM measurements were performed in order to analyze the structure of the films. Resistivity as a function of temperature, current–voltage characteristics in electric current induced Joule heating transition process, and the optical transmittance both in insulator and metal states were measured. MIT effect led to 10³–10⁵ change in resistivity with varying transition temperature and hysteresis loop widths. The largest and the steepest transitions were found in the films with polycrystalline microstructure deposited at higher oxygen pressures. Epitaxial films had 2.5 times higher insulator state conductivity than polycrystalline films, which lead to a clearly smaller switching powers in MIT effect generated by Joule heating. However, the optical properties in both states were not considerable affected by conductivity or microstructure properties. The relationships between the microstructure, electrical and optical properties, as well as MIT switching effect together its dynamics in the films are discussed.     

Electrical characterization and parameter extraction of organic thin film transistors using two dimensional numerical simulations

In this paper a performance based comparison of top and bottom contact organic thin film transistor (OTFT) device structures, using two dimensional numerical simulations has been carried out. In addition to this, investigations pertaining to the estimation of contact resistance in these OTFTs were also performed. To estimate contact resistance the conventional transmission line method and modified transmission line method (M-TLM) were respectively invoked. Our simulation results clearly indicate that the latter is more accurate in the estimation of contact resistance compared to the conventional method. Furthermore, the M-TLM was used to estimate the gate voltage and film thickness dependence of the contact resistance for the two device structures. The observed results have been explained on the basis of the significantly lowered area of carrier injection and extraction regions, at the source/channel and channel/drain interface respectively, in bottom contact transistor that lead to its inferior performance over the top contact transistor.