Advanced Materials Research Vols. 712-715

Abstract: For the valve-regulated lead-acid (VRLA) battery, an on-line activation system is designed, which is composed of personal computer (PC), sixteen bits MCU, touch-screen, mass FLASH memory, ferroelectric random access memory (FRAM), Ethernet interface, USB interface, charging module, discharging module, and so on. The charging module is designed based on distributed power supply with low voltage and large current, and using the method of intelligent segmentation-limit-current to realize nondestructive charging. The discharging module is designed with technologies of PID and PWM, and battery discharging with constant current can be realized by controlling the power switches. Test results present that the system runs stably, can activate and repair the battery well in the early days of losing efficacy.

Abstract: The La_0.75Sr_0.25Cr_0.5Mn_0.5O_3-δ nanometer powders were prepared by citric acid sol-gel method. The samples were characterized by DTA, FT-IR, XRD, TEM techniques. The preparation process, morphology of synthesized powders, the best heat-treatment temperature and the electrochemical performance had been studied. The results show that the spherical nanometer powders can be obtained and the best heat-treatment temperature is 800°C. The particle size is about 30nm and Ea is 0.071 eV.

Abstract: The Ba_0.8Sr_0.2TiO₃/CoFe₂O₄ layered heterostructure film was grown on Pt/TiO₂/SiO₂/Si substrate by radio frequency-magnetron sputtering. X-ray diffraction shows that the heterostructure film is composed of perovskite Ba_0.8Sr_0.2TiO₃ phase and spinel CoFe₂O₄ phase. The microstructures of the heterostructure film were observed by field-emission scanning electron microscope (FESEM), showing good surface morphology and clear interfaces among the Ba_0.8Sr_0.2TiO₃ film and CoFe₂O₄ film and substrate. The heterostructure film simultaneously diplays distinct ferroelectricity and ferromagnetism. Moreover, an obvious direct magnetoelectric coupling effect is observed in the heterostructure film with a maximum magnetoelectric voltage coefficient of 9.4 mV/cm Oe.

Abstract: Lead zirconate titanate (PZT) ceramics are widely applied in manufacturing transducers, sensors etc [1-3]. In all of these applications, the PZT ceramic plates are bonded with a metal substrate making out to an actuator for generating a deflection. Large amount of research work has been done on investigating electrical properties [4-6] of the PZT ceramic plates, the influence of the environmental factors on their performance and mechanisms of electrical degradation phenomenon [7-9]. In this paper, two kinds of metal substrates (Kovar alloy and Titanium) are applied for bonding with the PZT ceramic plates. Experimental results show that, the materials of metal substrates are also severely influence the output deflections of the PZT actuators. In general, for both the two types of samples, they are with a better deflection at a higher working temperature, but the PZT actuator samples with Kovar alloy substrate is with better net deflection.

Abstract: A new organic silicane which is bridged by a long amino-functionalized alkyl chain was prepared and used as the precursor in the synthesis of a series of PMO materials. The organic silicane was added into the reaction system in CH₂Cl₂ and the PMO materials were prepared by a simple stirring method under acidic condition, with a nonionic surfactantBrij 76 as template. To find the proper synthesis condition, the time of stirring and the proportion of organic silicane and TEOS were varied. Liquid and solid state NMR, X-ray diffraction (XRD) patterns, thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and N₂-physisorption properties were used to characterize the structures.

Abstract: Sodium tungsten bronze Na_xWO₃ powders have been prepared by hydrothermal method using sodium tungstate as raw material and citric acid as reducing agent, followed by annealing under the inert gas N₂ atmosphere. The prepared powders were confirmed as tetragonal sodium tungsten bronze Na_0.1WO₃ by X-ray diffraction. The SEM observation showed that the as-prepared Na_0.1WO₃ particles exhibited rod-like morphology with about 20 μm in length and 5 μm in diameter. The influence of pH value of the precursor solution and annealing temperature on the synthesized powders were also investigated. The results indicated that sodium tungsten bronze Na_XWO₃ would not be obtained when the pH value of the precursor solution decreased to pH=1 or the annealing temperature was lower than 700°C by this hydrothermal method. Additionally, as the wavelength increasing, the transmittance of prepared Na_xWO₃ exhibited higher visible light transparency with reaching up to about 58% and a downward trend in near-infrared area, which indicates that the prepared Na_0.1WO₃ have potential application as near-infrared shielding material.

Abstract: Using sodium tungstate and cesium carbonate as raw materials, cesium tungsten bronze (Cs_xWO₃) powders were synthesized by low temperature hydrothermal reaction with citric acid as the reducing agent. Effects of annealing in different atmosphere on the near-infrared shielding properties of Cs_xWO₃ were investigated. The microstructure of Cs_xWO₃ powders was characterized by X-ray diffraction. The Cs_xWO₃ films were prepared on glass using polyvinyl alcohol solution as film-forming agent, and the optical transmission properties of Cs_xWO₃ films were investigated. The results indicate that the near-infrared shielding ability of samples after annealed at 200°C in the air atmosphere did not deteriorate apparently, but the 400°C-annealed samples in the air atmosphere showed apparent decrease of near-infrared shielding properties. Annealing in the carbon powder atmosphere had no apparent effects on the properties of Cs_xWO₃ particles. As for the N₂ annealing, the 500°C-annealed samples showed best improved near-infrared shielding as well as high transparency in the visible light region.

Abstract: The crystallographic, magnetic and electronic structures of the magnetic shape memory alloys Ni₂XIn (X=Mn, Fe and Co) are systematically investigated by means of the ab initio calculations within the framework of density functional theory. The equilibrium lattice parameters and the bulk modulus of the austenitic phase in Ni₂XIn are systematically calculated. The formation energy of the L2₁ phase of the Ni₂XIn is estimated, and displays a destabilization tendency if Mn atom is substituted by Fe or Co. Furthermore, the magnetic properties of the Ni₂XIn have been investigated, and the essence of the variation in the magnetic properties with the X atomic number has been illustrated from the view of the electronic density of states.

Abstract: Pt/Bi_3.15Nd_0.85Ti₃O₁₂(BNT)/Pt ferroelectric capacitors were monitored using in situ X-ray irradiation with 10 keV at BL14B1 beamline (Shanghai Synchrotron Radiation Facility). BL14B1 combined with a ferroelectric analyzer enabled measurements in situ of electrical performance. The hysteresis curve (PE) of distortion depended on the polarization during irradiation, but the diffracted intensities of the (117) peak did not change in the beginning. The PE curve had a negligible change from 2.09×10⁹ Gy to 4.45×10⁹ Gy. Finally, both P_r and P_r+ very rapidly increased, but the intensities of (117) decreased. The hysteresis loops were remarkably deformed at the maximum total dose of 4.87×10⁹ Gy.

Abstract: Octyltrimethoxysilane was synthesized by octane and trimethoxysilane, and octane was synthesized by grignard reagent. The main effects of reacting conditions on the yield were discussed and the optimum experimental conditions were studied. Used 3-bromopropene and 1-Brompentane as raw materials, the molar ratio of octane: magnesium was 1:1.2. Droplets time was 3 hours, the reacting time in 1 hour, and yield was 45.6%. Target compounds were analysised through GC-MS. Then, used choroplatinicacid isopropanol as catalyst, octane reacted with trimethoxysilane to gain octyltrimethoxysilane, the time of activation of catalyst was 1 hour ,reacting time 1 hour, and the yield was up to 65.4%. Study found that using 1-Brompentane Grignard reagent and 3-bromopropene could extend the carbon chain successfully. On the contrary, using 3-bromopropene Grignard reagent and 1-Brompentane to react, the rate of conversion was very low, a large number of decane generated, rather than octane.