Effect Of Li Addition Research Articles

Effect of Li Addition into NayLixMn1-zCozO2 Cathode Materials

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Characterisation of dynamic recovery during hot deformation of spray formed Al–Li alloy (UL40) using processing map approach

Processing maps, also known as power dissipation maps, for spray formed Al–Li alloy (UL40), encompassing a wide range of hot working temperature (375–575°C) and strain rate (3 × 10−4–101 s−1) have been developed. The constant true strain rate compression tests were carried out under isothermal conditions to generate the stress–strain data required for computing the efficiency of power dissipation η. The maps exhibit three distinct regimes. The two high efficiency (>55%) regimes occur at the low strain rates (<10−3 s&minus1) and at the high strain rates (>1 s−1), and the other with moderate efficiency values (20–23%) occurs at the intermediate strain rate (10−1 s−1). The latter one has been interpreted to be associated with dynamic recovery (DRV) process while the other two regimes have been found to be associated with cracking processes. The DRV regime in the map has been characterised in terms of stress–strain response, microstructure and tensile ductility. The kinetic rate analysis carried out in the DRV regime suggested that the thermally activated cross-slip is the rate controlling mechanism for the DRV process. The effect of Li addition on the optimum deformation condition of DRV in Al has also been discussed qualitatively.

Effect of Li Addition on Structural, Electrical and Electrochemical Properties of Lanthanum Manganite.

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Effect of Li addition on structural, electrical and electrochemical properties on lanthanum manganite

The addition of aliovalent element plays an important role on the structural, electrical and electrochemical properties of LaMnO 3. In this study, 10% of Li was incorporated into the A-site of the LaMnO 3 perovskite. The addition of more than 10% Li resulted in the formation of the LiMn 2O 4 spinel as a second phase. The conductivity of LaMnO 3 was also effectively enhanced by the addition of Li. The undoped LaMnO 3 exhibits a conductivity of 0.25 Ω −1 cm −1 at 27 °C. In the LaMnO 3 sample doped with 10% Li, the conductivity increased to 2.25 Ω −1 cm −1 at 27 °C. For 30% Li-doped LaMnO 3, the lower conductivity of 1.31 Ω −1 cm −1 at 27 °C was observed due to the formation of poor-conducting LiMn 2O 4. In all the samples doped with Li, the activation energy (17.20–18.17 kJ/mol) for electrical conduction was much lower than that of undoped LaMnO 3 (26.71 kJ/mol). The reduction in activation energy can be rationalized by the creation of electron holes due to the addition of Li. In the sample with the composition of La 0.9Li 0.1MnO 3, the cyclic voltammetry and charge/discharge tests indicated that the sample was not electrochemically active.

Effect of Li addition on the properties of Bi-based superconductors

The effect of Li addition on the formation and properties of Pb containing Bi-based superconductors has been studied. Three successive thermal sintering cycles have been applied to the oxides adjusted for the nominal composition, Bi/sub 1.6/Pb/sub 0.4/Sr/sub 2/CaCu/sub 2/O/sub 8+d/. Eight different samples having Li/sub 2/CO/sub 3/ from 0.0 up to 3.0 weight% have been synthesized. X-ray diffraction patterns, resistivity-temperature behaviors and differential thermal analysis of the samples have been examined. Li/sub 2/CO/sub 3/ addition at 650 /spl deg/C decreases the fraction of (Bi,Pb)-2212 and increases that of Ca/sub 2/PbO/sub 4/. The normal state resistances of the samples increase, the onset T/sub c/ values decrease and the lattice parameters almost remain same with Li/sub 2/CO/sub 3/ addition. Li/sub 2/CO/sub 3/ addition up to 3.0 wt% decreases the melting temperature of (Bi,Pb)-2212 phase by about 50/spl deg/C inducing a liquid phase at about 750 /spl deg/C. Our observations suggest that the high T/sub c/ phase, (Bi,Pb)-2223 may be formed at about 750-800 /spl deg/C using the precursors, (Bi,Pb)-2212 and Ca/sub 2/PbO/sub 4/ doped with Li/sub 2/CO/sub 3/.

Effect of Li addition on crystal structure and phase separation of highly defective (La,Li)TaO 3 solid electrolytes

La 1/3TaO 3 was found to exhibit a perovskite structure in which two-thirds of A-cation sites are vacant. An ordered arrangement of vacancies causes the formation of a superstructure with doubled c-axis compared with a perovskite subcell. With small amount of Li addition, a superstructure with vacancies located at the (002) plane was still present. When Li ions were added into more than 20% of A-cation sites, the superstructure disappeared and the perovskite structure also changed from tetragonal to near cubic. When more than 60% of A-cation sites were incorporated by Li ions, a phase separation of cubic La 0.166Li 0.5TaO 3 perovskite and rhombohedral LiTaO 3 was observed. The phase separation was caused by the big difference of ionic radius between La and Li ions. The microstructure and microchemical analysis of (La,Li)TaO 3 were examined using scanning electron microscopy and EDX.

Melt-Casting法を用いて作製したBi2212バルク超電導体の臨界温度に対するLi添加効果

Melt-Casting法を用いて作製したBi2212バルク超電導体の臨界温度に対するLi添加効果

Morphology and Cathodoluminescence of Li-Doped SrTiO3:Pr3+,Ga3+, A Red Phosphor Operating at Low Voltages

ABSTRACTSrTiO3:Pr,Ga phosphor using Li2CO3 as a flux has been investigated as a red phosphor for the application to fluorescent displays operated at low voltage. In SrTiO3:Pr,Ga system, Pr3+can substitute for Sr2+ because the ionic radius of Pr3+almost coincides with that of Sr2+. Previous work, it was found by XRF analysis of SrTiO3:Pr,Ga single crystal that only a small fraction of Pr ions are incorporated in the SrTiO3 lattice. In the present study, the effect of Li addition into SrTiO3:Pr,Ga on the cathodoluminescence (CL) properties was examined at low acceleration voltage. Especially, thanks to the liquid phase of Li2CO3 during the sintering process, doped Li ions act as a lubricant for the efficient incorporation of Pr ions into SrTiO3:Pr,Ga lattice. Furthermore, it is found that the Li addition could enhance the generation of the characteristic emission of Pr-activated SrTiO3phosphors.

酸化物超伝導体の合成と特性 Ｌｉ添加Ｂｉ‐２２１２相の生成過程 第２報 低温生成機構の検討

Effects of Li-addition on the formation process of Bi-2212 phase have been studied for samples with a nominal composition of Bi:Sr:Ca:Cu:Li=2:1.5:1.5:2:0.2. Samples were heated at temperatures ranging between 560°C and 730°C in air with various heating rates. The formation range of the phases formed was determined by powder X-ray diffraction method(XRD). Li-addition seems to bring two different effects on the formation process of the Bi-2212 phase: an acceleration of the formation of Bi-2201 phase on heating and early stage of holding at 730°C, and a promotion of phase transformation of Bi-2201 phase to Bi-2212 phase after holding for a few hours. Such two effects can be explained by formation of two different oxides which were newly found. The microstructures of the newly found oxides were observed by scanning electron microscopy(SEM), high-resolution transmission electron microscopy(HR-TEM) and electron diffraction(ED).

Effects of lithium addition and wheel velocity on the microstructure of aluminium-lithium alloy ribbons

The effects of Li addition and wheel velocity on the microstructure of as-cast AI-Li ribbons were studied by optical metallography, scanning and transmission electron microscopy and by X-ray diffraction. Li addition has a marked effect on the ribbon solidification mechanism. Ribbons spun at 12.5 ms−1 and which contained up to 1.79 wt% Li experienced a cooling rate of about 104 Ks−1 and solidified under the melt jet with a growth rate greater than 0.3 m s−1. However, when Li content exceeded about 3 wt%, the ribbons were undercooled (cooling rate ≈ 106 Ks−1) and formed far from the melt puddle effect. Under these conditions, unusual secondary featureless zones occurred through the ribbon thickness and the detected phases corresponded to those expected to be formed under equilibrium conditions. Nevertheless, δ′ (AI3Li) phase did not occur in ribbons containing up to 1.79 wt % Li or in the featureless zones of the most Li-rich ribbons (Li >about 3 wt%). Changing of the wheel velocity from 12.5 to 22.2 or 35.7 ms−1 did not affect the ribbon formation mechanism, but it favoured the δ′ precipitation and decreased slightly the grain size.

Ｂｉ‐Ｐｂ‐Ｓｒ‐Ｃａ‐Ｃｕ‐Ｏ系高温相へのＬｉ添加効果 （第Ｉ報）

Ｂｉ‐Ｐｂ‐Ｓｒ‐Ｃａ‐Ｃｕ‐Ｏ系高温相へのＬｉ添加効果 （第Ｉ報）

Ｂｉ‐Ｐｂ‐Ｓｒ‐Ｃａ‐Ｃｕ‐Ｏ系高温相へのＬｉ添加効果 （第ＩＩ報）

Ｂｉ‐Ｐｂ‐Ｓｒ‐Ｃａ‐Ｃｕ‐Ｏ系高温相へのＬｉ添加効果 （第ＩＩ報）

Ｌｉ添加したＢｉ２Ｓｒ２ＣａＣｕ２Ｏｘ厚膜および薄膜の超伝導特性

The effect of Li addition to Bi2Sr2CaCu2Ox thick and thin films on their superconducting properties was investigated. Bi2Sr2CaCu2Ox superconducting films were successfully obtained at low temperatures below 840°C by addition of Li2CO3, which acted as a flux. The superconducting transition temperature (Tc) of films increases with increases in Li content, accompanied with an increase of the length of c-axis. The thick and thin films show Tc zero of 88 K and 81 K, respectively, which are higher than that of undoped Bi2Sr2CaCu2Ox.