Structure,stability and optical parameters of cobalt zinc borate glasses

In this study, the impact of cobalt oxide (CoO) on the structure, stability, linear and nonlinear optical parameters of B₂O₃–Na₂O–ZnO glasses was scrutinized. A series of glass system (ZnCoNaB-glasses) was successfully prepared through the melt quenching approach. Optical absorbance, reflectance, transmittance and FTIR spectroscopy were performed for all ZnCoNaB-glasses. The FTIR results showed that the BO₄ units are enhanced while nonbridging oxygens are decreased with further CoO addition. Furthermore, ZnO exists as four-coordinated [ZnO₄] units and these units decreased with further doping of CoO. These structural variations produce a decreasing impact in Urbach energy and nonlinear refractive index, meanwhile enhance the glass stability. Further, the metallization criterion (M) values indicate that our glass samples can be used for a new generation of nonlinear optical glasses. The preceding results can predict that the investigated ZnCoNaB-glasses will be utilized in versatile applications; especially optical switching and computing.     

CoO膜厚对磁控溅射Co/CoO薄膜结构和磁性能的影响

为了探究FM/AFM双层膜中的交换偏置现象,利用磁控溅射法制备Co/Co O薄膜,通过改变沉积时间获得了不同Co O层厚度的Co/Co O双层膜系。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、交变梯度磁强计(AGM)、超导量子干涉仪(SQUID)分别对样品的物相结构、表面形貌及磁性能进行分析和表征。结果表明,AFM层厚度对表面形貌有一定的影响,但表面成分不随AFM层厚度的变化而变化。所有样品的XRD谱均出现Co O(002)衍射峰,说明薄膜为晶态。不同厚度的Co/Co O双层膜样品表现出不同的矫顽力和偏置场,低温下样品的磁滞回线表现出明显的交换偏置效应,并且磁偏移量随膜层厚度增加呈现逐渐增大的趋势。当Co O厚度为62.5nm时,偏置场最大可达到420k A/m。     

Electrochemical Performance of PrBaCo2O5+δ and Sm0.5Sr0.5CoO3−δ Infiltrated Ce0.9Gd0.1O1.95 Cathodes

Cathodes with PrBaCo₂O_5+δ (PBC) and Sm_0.5Sr_0.5CoO_3−δ (SSC) infiltrated on Ce_0.9Gd_0.1O_1.95 (CGO) backbones are prepared using metal nitrates as precursors and ethanol as wetting agent. Electrochemical impedance spectra (EIS) are measured from cathode/CGO/cathode symmetrical cells in 400–650 °C under humidified air. The results indicate that interfacial area specific resistance (ASR) value decreases and then increases with infiltrate loading and minimum values occur at 50 wt.% loading (relative to sum of infiltrate and backbone) for both PBC and SSC infiltrates. ASR values of PBC infiltrated cathodes are lower than that of corresponding SSC infiltrated cathodes in general, and in particular ASR values as low as 1.36 × 10⁻² and 2.27 × 10⁻² Ω cm² are obtained at 650 °C in air for 50 wt.% PBC and 50 wt.% SSC infiltrated cathodes, respectively. Conductivity values of CGO electrolyte increase with infiltrate loading and agree with the reported values when the loading reaches 50 wt.%.     

NaxCoO2·yH2O体系的高分辨电子能量损失谱和电子结构研究

本文通过高分辨电子能量损失谱(EELS)的实验分析与密度泛函计算相结合的方法,研究了NaxCoO2·yH2O系统的电子结构特性和电子关联效应.实验结果表明,金属性Na0.3CoO2材料和电荷有序绝缘体Na0.5CoO2的O-K吸收边存在明显的结构差别,在Na0.5CoO2的EELS中第一个峰发生明显分裂,密度泛函计算证实这种分裂现象和电子关联效应直接相关.通过理论模拟谱线与实验谱线的比较确定了其电子关联强度为U=3.0 eV.在Na0.3CoO2·yH2O(y=0,0.6,1.3)超导体系中,实验发现其能损谱的低能部分随着水含量的增加发生系统的变化,损失峰向低能量方向逐步移动.电子结构计算表明水分子的插入可以引起费米面附近能态原子轨道杂化情况的改变,从而导致EELS的变化.     

CoO作为电极材料的可能性

以烧结Ni(OH)2为对电极,以Inco Ni粉为导电剂,对CoO作为电极材料使用时的电化学性能进行了测试和分析。结果表明:CoO在室温时的放电容量远高于镉-镍电池中的CdO和氢-镍电池中的商业化AB5贮氢合金,且受温度影响不大,充放电循环稳定性较好。不足之处是其放电电压平台较低,在充放电循环时,放电容量有波动。     

Continuous hydrothermal synthesis of HT-LiCoO2 in supercritical water

A detailed investigation was made into the production of high temperature lithium cobalt oxide (HT-LiCoO₂) particles by continuous hydrothermal synthesis via the reaction of cobalt nitrate, lithium hydroxide, and hydrogen peroxide. The experiments were carried out in both subcritical and supercritical water, at temperatures ranging from 300 to 411 °C, with residence times less than 1 min in all instances. Although Co₃O₄ particles were synthesized in subcritical water at similar reaction conditions designed for comparison, well-ordered particles of HT-LiCoO₂ were obtained in supercritical water. In supercritical conditions, the variations in temperature and residence time did not have significant impacts on the average particle size, particle size distribution, or morphology of obtained HT-LiCoO₂. However, it was important to supply excessive lithium hydroxide and hydrogen peroxide in order to synthesize single-phased HT-LiCoO₂ particles without undesired by-products. The hydrothermal synthetic route for LiCoO₂, CoO, and Co₃O₄ in both subcritical and supercritical conditions was postulated.     

Characterization and Stability of La0.5Sr0.5CoO2.91 Perovskite-Type Oxide

Compositely doped oxide La0.5Sr0.5CoO2.91 （LSC） was synthesized using solid state reaction and citric acid-nitrate low temperature self-propagating combustion methods. The crystal structure and the particle size micrograph of LSC powders synthesized by different methods were investigated with XRD and SEM. The experimental results show that the single perovskite phase of LSC can be synthesized by solid state reaction method, but LaSrCoO4 phase appears in LSC powder synthesized by citric acid-nitrate low temperature self-propagating combustion method. The LSC particle by citric acid-nitrate low temperature self- propagating combustion method has smaller size. To analyze the character of cathode material based on Ceo.gGdo.101.95（GDC） electrolyte, two types of cathode wafers were fabricated with the two kinds of LSC and GDC powders at the mass rate of 6：4, respectively. The electrical conductivity of the sintered samples was measured by four probe DC method from 300 to 800 ℃. The cathode with LSC particle by citric acid- nitrate low temperature self-propagating combustion method has higher electrical conductivity. In order to investigate the stability, the two samples were put into the muffle furnace to heat up in air at 800℃for 800 h. To analysis the reason for reduced electrical conductivity, the crystal structure and the particle micrograph of the cathode wafers before and after an exposure were investigated with XRD and SEM. The result shows that new crystal structure appears in both the two kinds of cathode wafers and crystal micrographs change a lot.     

Exploration of artificial neural network [ANN] to predict the electrochemical characteristics of lithium-ion cells

CoO anode, as an alternate to the carbonaceous anodes of lithium-ion cells has been prepared and investigated for electrochemical charge-discharge characteristics for about 50 cycles. Artificial neural networks (ANNs), which are useful in estimating battery performance, has been deployed for the first time to forecast and to verify the charge-discharge behavior of lithium-ion cells containing CoO anode for a total of 50 cycles. In this novel approach, ANN that has one input layer with one neuron corresponding to one input variable, viz., cycles [charge-discharge cycles] and a hidden layer consisting of three neurons to produce their outputs to the output layer through a sigmoid function has been selected for the present investigation. The output layer consists of two neurons, representing the charge and discharge capacity, whose activation function is also the sigmoid transfer function. In this ever first attempt to exploit ANN as an effective theoretical tool to understand the charge-discharge characteristics of lithium-ion cells, an excellent agreement between the calculated and observed capacity values was found with CoO anodes with the best fit values corresponding to an error factor of <1%, which is the highlight of the present study.     

用粉末X射线衍射数据确定晶胞参数的方法

介绍了从晶体粉末Ｘ射线衍射数据确定其晶胞参数的方法。并用该法求得四方体心晶体结构的锂铜酞花菁ＬｉＣｕＰｃ的晶胞参数ａ＝１．７３６７ｎｍ，ｃ＝１．３６４０ｎｍ，三方晶系Ｒ＾３ｍ空间群结构的锂钴氧化合物Ｌｉ０．５ＣｏＯ２按六方格子划分的晶胞参数ａ＝０．２８０８ｎｍ，ｃ＝１．４０７９ｎｍ。     

Sm0.5Sr0.5CoO3–Sm0.2Ce0.8O1.9 Composite Oxygen Electrodes for Solid Oxide Electrolysis Cells

In this paper, a series of Sm_0.5Sr_0.5CoO₃–Sm_0.2Ce_0.8O_1.9 (SSC–SDC) composite with different ratios were prepared and characterized as oxygen electrodes for solid oxide electrolysis cells (SOECs). Yttria‐stabilized zirconia (YSZ) was selected as the electrolyte with a SDC barrier layer to avoid detrimental solid state interaction between SSC and YSZ. At 850 °C, the impedance spectra showed that the optimum SDC content in the composite electrode was found to be about 30 wt.%, which showed a much lower area specific resistance of 0.03 Ω cm². The electrochemical performances of a Ni–YSZ hydrogen electrode supported YSZ membrane SOEC with the SSC–SDC73 oxygen electrode were also measured at 750–850 °C. The hydrogen production rate calculated from the Faraday's law was 327 mL cm^–2 h^–1 at 850 °C at an electrolysis voltage of 1.3 V with a steam concentration of ∼40%, which indicated that the SSC–SDC73 was a promising oxygen electrode candidate for high temperature electrolysis cells.