2b Sites Research Articles

Fascinating functional properties of Mn:Gd2O3 nanocrystalline phosphor

In the present work we through the light on some of the fascinating structural, magnetic and optical properties of Mn:Gd2O3 nanophosphor. Manganese substituted nanocrystalline Mn:Gd2O3 was prepared via a sol gel procedure. The prepared samples were characterized applying X-ray diffraction (XRD), infrared spectroscopy (IR), squid magnometer and photoluminance (PL). XRD and IR analysis revealed a single phase solid solution up to x=0.2. The cation distribution of Mn and Gd between the crystallographically non-equivalent sites 8b and 24d of the space group Ia3¯ is found to be preferentially for all samples. The lattice parameter decreases with composition x, accompanied with systematic variation in the r.m.s. microstrain 〈εL2〉1/2.The magnetic measurement showed negative values for curie paramagnetic temperatures, θ, which indicates an antiferromagnetic interaction between the magnetic ions in Mn:Gd2O3. PL spectra showed a series of emission lines in the room temperature fluorescence measurements under UV excitation (220nm). The observed emission lines are stokes-shifted and the non-linearity optical phenomenon is confirmed. Further, the emission lines are slightly shifted with Mn concentration (x). The blue emission around (390–402) nm was appeared due to Mn doping. Because of its fascinating properties, Mn:Gd2O3 is recommended for fuel cells, photocatalytic, and biomedical applications.

A Mössbauer investigation of Sr1−xLaxFe12O19 (0≤x≤1) M-type hexaferrites

Sr1−xLaxFe12O19 hexaferrite powders prepared using a standard ceramic process were investigated by Mössbauer spectrometry, thus allowing investigating the influence of the Sr2+/La3+ substitution on the five Fe sublattices in the whole range of composition. Very satisfactory fittings are obtained accounting for the Fe2+/Fe3+ charge compensation mechanism at the 2a site due to the replacement of Sr2+ by La3+. The evolutions of the hyperfine parameters (hyperfine field, isomer shift and quadrupolar shift) of the contributions related to the five iron sites are continuous. They are interpreted in relation with the Sr2+/La3+ substitution. The results show that the 12k, 4f2 and 2b sites are the most affected by the substitution, in agreement with both the evolution of the lattice constants and the fact that these three sites have Sr sites in their close vicinity.

Co–Ti co-substitution of M-type hexagonal barium ferrite

This paper reports a study of Co–Ti equiatomic co-substitution of M-type hexagonal barium ferrites Ba(CoTi)xFe12−2xO19, with the objective to adjust coercivity to meet different application requirements. The ferrites, with x = 0.00−1.30, all exhibited the single-phase M-type barium ferrite structure. At x = 1.30, the saturation magnetization (MS) decreased by 27.7% to 47.5 Am2 kg−1 and the coercivity (HC) decreased from 4047 to 171 Oe, providing a wide control range of coercivity. Complex magnetic permeability (μ′ and μ″) was measured to be μ′max = 25 and μ″max = 1.5 (at 10 MHz). The value of μ′ is much higher than that of un-doped barium ferrite (x = 0.00). Co–Ti substitution reduced the coercivity whilst increased magnetic permeability. These improvements in magnetic properties are attributed to Co and Ti occupancies at different sites in the barium ferrite crystalline structure. Substitution is preferred at 4f2, 2b and 2a sites at x < 0.50, but 2a and 4f1 sites at x < 1.15. In addition, the bulk density (ρ) of the sintered compound was found to increase with increasing Co–Ti substitution.

Investigation of Site-Selectivity and Crystal Structure of Boron-Incorporated B2-Type AlNi Matrix

We investigated in the B site-selectivity and induced modifications in the crystal structure, when B is introduced into the B2-type AlNi matrix (Pm-3m; Al at 1a, Ni at 1b). A rapid-quench from higher temperatures of all nominal AlNiBx and Al2Ni3Bx/3 compositions (0≤ x ≤ 3) leads to the formation of a cubic solid solution. On the other hand, diffraction studies indicate that all (unquenched) AlNiBx (1≤ x ≤ 3) compositions are chemically unstable. By contrast, for 0≤ x ≤ 1 there is a strong preference of B to enter substitutionally into the 1b site: then composition balance is achieved by transferring a Ni atom into a 1a antisite.

Features of the band structure and conduction mechanisms of n-HfNiSn semiconductor heavily Lu-doped

The crystal and electronic structures, energy, kinetic, and magnetic characteristics of n-HfNiSn semiconductor heavily doped with a Lu acceptor impurity in the ranges T = 80–400 K and NALu ≈ 1.9 × 1020−1.9 × 1021 cm−3 (x = 0.01–0.10) at H ≤ 10 kG is studied. The nature of the structural-defect generation mechanism leading to changes in the band gap and the degree of semiconductor compensation is determined. Its essence is the simultaneous reduction and elimination of donor-type structural defects due to the displacement of ∼1% of Ni atoms from the Hf (4a) site, the generation of acceptor-type structural defects by substituting Ni atoms with Lu atoms at the 4c site, and the generation of donor-type defects such as vacancies at the Sn (4b) site. The results of calculations of the electronic structure of Hf1 − xLuxNiSn are in agreement with experimental data. The results are discussed within the model of a heavily doped and compensated Shklovskii-Efros semiconductor.

Crystal structure study of a cobaltoan dolomite from Kolwezi, Democratic Republic of Congo.

A structural study has been undertaken on a cobaltoan dolomite, with chemical formula CaMg0.83Co0.17(CO3)2 (cal­cium magnesium cobalt dicarbonate), from Kolwezi, Democratic Republic of Congo. Pale-pink euhedral cobaltoan dolomite was associated with kolwezite [(Cu1.33Co0.67)(CO3)(OH)2] and cobaltoan malachite [(Cu,Co)2(CO3)(OH)2]. A crystal with a Co:Mg ratio of 1:5.6 (SEM/EDAX measurement), twinned on (11 -2 0) was used for crystal structural refinement. The refinement of the structural model of Reeder & Wenk [Am. Mineral. (1983 ▸), 68, 769–776; Ca at site 3a with site symmetry -3; Mg site at site 3b with site symmetry -3; C at site 6c with site symmetry 3; O at site 18f with site symmetry 1] showed that Co is totally incorporated in the Mg site, with refined occupancy Mg0.83Co0.17, which compares with Mg0.85Co0.15 from chemical data. The Co substitution reflects in the expansion of the cell volume, with a pronounced increasing of the c cell parameter.

Reduction of the lithium and nickel site substitution in Li1+xNi0.5Co0.2Mn0.3O2 with Li excess as a cathode electrode material for Li-ion batteries

Layered Li1+xNi0.5Co0.2Mn0.3O2 (x=0, 0.02, 0.04, 0.06, 0.08) materials were synthesized using the co-precipitation method. Rietveld refinements measurements reveal that the concentration of Ni2+-3b ions decreases from 0.06 to 0.043, with x changing from 0.02 to 0.08. The initial coulombic efficiency improves with the increase in the content of Li-excess because the content of Ni at the 3b site decreases with the increase of Li-excess in the samples from 0 to 0.08. The analysis indicates that Li1.08Ni0.5Co0.2Mn0.3O2 exhibits the largest diffusivity value due to the dependence of the diffusion coefficient of lithium ions on the content of Ni in the 3b sites.

The role of nanoscale-range vanadium treatment in LiNi0.8Co0.15Al0.05O2 cathode materials for Li-ion batteries at elevated temperatures

A nano-scale surface protecting layer of LiNi0.8Co0.15Al0.05O2 consisting of substituted V4+ ions in 3b sites leads to structural robustness under the most challenging test conditions.

설계과제 수행을 위한 정보화 과정 교수학습 사례연구 - 도시재생을 주제로 한 건축설계수업 연계 단지설계 통합수업을 중심으로 -

This study proposes to examine the learners' informatization process that was taken place in order to support a set of urban revitalization projects developed as an architectural design task. For the purpose, two different in content but deeply integrated to each other courses(architectural design 3B studio and site design) held in Fall semester 2013 were organized to operate and manage the process. The former is largely planned to focus on practice-oriented task performance, while the latter is designed to support it by providing a teaching and learning organization of work for stimulating the informatization process. The study is likely to be a reporter of the author's liable teaching and learning experience as related to the latter part. Theoretical debate on design as results of a series of informatization process was undertaken. In addition, a teaching and learning conceptual model for solving ill-defined problems in urban revitalization and public design was developed for use. Two types of informatization were identified in the model for test; (1)situational and (2)problem solving. In order to validate results of the study, a set of multiple analytical tools such as student reports submitted, interview/survey/observation summary scripts were utilized. A total of 3 research problems were developed. Each is related to (1)informatization contents and characteristics among learners, (2)the effect of the informatization process on problem solving, (3)easiness of learning it between learners in different grades. Results of the study show that different strategies for teaching and learning the informatization process are necessary for students of different task performance abilities, because learners in A grade are significantly different with ones in B grade in terms of how to cognitively view, organize, set a basic direction to solve an identical set of problems. To students in a lower grade, informatization might be perceived to be a possibility for solving multiple and diverse ill-defined problems as well as difficulty for understanding.

On the Structure and Stability of BaAl4‐Type Ordered Derivatives in the Sr–Au–Sn System for the 600 °C Section

Abstract The well‐known BaAl4‐type structure consists of three ordered ternary derivatives, i.e., BaNiSn3‐ (I4mm), ThCr2Si2‐ (I4/mmm), and CaBe2Ge2‐type (P4/nmm). Few systems, such as Ba‐Au‐Sn, have been confirmed to manifest all three types as a function of valence electron count. In this work, the SrAuxSn4–x solid solution at the 600 °C section was studied thoroughly using both single crystal and powder X‐ray diffraction. The crystal structures and phase width for the CaBe2Ge2‐type SrAuxSn4–x solid solution were established to be a = 4.6528(2)–4.6233(3) Å and c = 11.3753(4)–11.2945(10) Å for x ≈ 1.65(1)–2.19(1). In the structure of SrAu2Sn2, no Au/Sn mixing was found, but for x &lt; 2 compositions, Au/Sn mixings were only located at the Wyckoff 2a (¾ ¼ 0) site and for x &gt; 2 compositions, at the 2b (¾ ¼ ½) site. Differential scanning calorimetry (DSC) analyses indicated that no phase transition occurred for the CaBe2Ge2‐type SrAuxSn4–x phase up to 950 °C. Attempts to synthesize the ThCr2Si2‐ and BaNiSn3‐type SrAuxSn4–x phases under the same reaction conditions were unsuccessful, and the BaNiSn3‐type phase could not be attained even at a pressure of 3 GPa. The instability of a BaNiSn3‐type “SrAuSn3” was investigated by both DSC measurements and first principles electronic structure calculations.

Unique thallium mineralization in the fumaroles of Tolbachik volcano, Kamchatka Peninsula, Russia. III. Evdokimovite, Tl4(VO)3(SO4)5(H2O)5

AbstractEvdokimovite, ideally Tl4(VO)3(SO4)5(H2O)5, was found in a fumarole of the 1st cinder cone of the North Breach of the Great Fissure Tolbachik volcano eruption of 1975–1976, Kamchatka Peninsula, Russia. Evdokimovite occurs as thin, colourless needles up to 0.09 mm long associated with shcherbinaite, pauflerite, bobjonesite, markhininite, karpovite and microcrystalline Mg, Al, Fe and Na sulfates. Evdokimovite is monoclinic, P21/n, a = 6.2958(14), b = 10.110(2), c = 39.426(11) Å , β = 90.347(6)º, V = 2509.4(10) Å3 and Z = 4 (from single-crystal diffraction data). The eight strongest lines of the powder X-ray diffraction pattern are (I/d/hkl): 57/9.793/011, 100/8.014/013, 26/6.580/006, 19/ 4.011/026, 29/3.621/118, 44/3.522/125, 19/3.010/036, 21/2.974/212. Chemical composition determined by the electron microprobe analysis is (wt.%): Tl2O 55.40, VO2 14.92, SO3 25.83, H2O 5.75, total 101.90. The empirical formula for evdokimovite calculated on the basis of (Tl + V + S) = 12 a.p.f.u. is Tl4.10V2.83S5.07H10.00O27.94. The simplified formula is Tl4(VO)3(SO4)5(H2O)5. The crystal structure was solved by direct methods and refined to R1 = 0.11 on the basis of 3660 independent observed reflections. V4+O6 octahedra and SO4 tetrahedra share common corners to form two types of vanadyl-sulfate chains, [(VO)(H2O)2(SO4)2]2– and [(VO)2(H2O)3(SO4)3]2–. Thallium atoms are located in between the chains. The structure can be described as a stacking of layers of two types, A and B. The A layer contains [(VO)2(H2O)3(SO4)3]2– chains and the Tl2 and Tl3 atoms, whereas the B layer contains [(VO)(H2O)2(SO4)2]2– chains and the Tl1 atoms. Stacking of the layers can be described as ...A’*BAA’B*A*..., where A and A’ denote A layers with opposite orientations of the [(VO)2(H2O)3(SO4)3]2– chains, and the A* and B* layers are rotated by 180º relative to the A and B layers, respectively. [(VO)2(H2O)3(SO4)3]2– chains are modulated and are arranged to form elliptical tunnels hosting disordered Tl(4), Tl(4A) and Tl(4B) sites. The new mineral is named in honour of Professor Mikhail Dmitrievich Evdokimov (1940–2010), formerly of the Department of Mineralogy, St Petersburg State University, for his contributions to mineralogy and petrology, and especially for teaching mineralogy to several generations of students at the University. Evdokimovite is the most complex V4+ sulfate known to date with structural information amounting to 1130 bits per unit cell, which places evdokimovite among minerals with the complexity of the vesuvianite group.

Synthesis, crystal structure, electronic structure and electrical conductivity of La3GeSb0.31Se7 and La3SnFe0.61Se7

The selenides La3EM1−xSe7 (La6E2M2−xSe14) adopt the Ce6Al3.33S14 structure type. La3GeSb0.31Se7 and La3SnFe0.61Se7 crystallize in the non-centrosymmetric space group P63 with La replacing Ce in the 6c site, E = Ge or Sn replacing Al in the 2b site and M = Fe or Sb replacing the other, deficient Al site (2a). The structure contains La atoms in square antiprisms of Se atoms, isolated distorted [ESe4] tetrahedra, and face sharing distorted [MSe6] octahedra forming a linear chain along the c-axis with short M–M distances. Band structure calculations predict semiconducting character with different gaps, which was demonstrated by electrical conductivity measurements and reflected in their different colors.

Characterization, average and electronic structures during charge–discharge cycle in 0.6Li2MnO3–0.4Li(Co1/3Ni1/3Mn1/3)O2 solid solution of a cathode active material for Li-ion battery

The 0.6Li2MnO3–0.4Li(Co1/3Ni1/3Mn1/3)O2 solid solution was prepared by the co-precipitation method. The average structure analysis based on the Rietveld method using neutron diffraction was carried out. As a result, the charging process eliminated Li from the transition metal layer as well as the lithium layer, and the dominant elimination of Li was suggested to be from the 2b site (S.G.; C2/m). The amount of the cation mixing of Ni at the 2c site in the Li layer tended to increase from the first to fifth cycles. It was suggested that Co moved to the 4g site after discharge, but to the 2b site after charging. On the other hand, the opposite tendency was shown for Mn. In addition, an electronic-structure analysis based on the Maximum Entropy Method was carried out. The covalent linkage increased in 4h-4i and 4h-8j between the first and fifth charge processes. It was also found that most of the Li in the 4h site was not extracted at the fifth cycle compared to the first cycle.

Er60Ni132: A new structure from the Ni occupied the 4b sites in cubic laves superstructure synthesized under high pressure and high temperature

The title compound with structure derived from cubic laves was fabricated by the high pressure high temperature (HPHT) method. A new structure single crystal Er60Ni132 was discovered in the experiment. The single crystal X-ray diffraction result showed that the symmetry of Er60Ni132 was F-43m with a 2a*2a*2a unit cell. Its structure was derived from the original cubic laves ErNi2 whose symmetry was Fd-3m. In comparison to the Fd-3m structure, the doubling of the unit cell occurred due to the ordering of Ni atoms substituting the Er atoms in 4b sites. The formation energies of ErNi2 and Er60Ni132 were computed and investigated. With the cubic Laves structure, the title compound also showed good hydrogen storage properties.

GlnR negatively regulates the transcription of the alanine dehydrogenase encoding gene ald in Amycolatopsis mediterranei U32 under nitrogen limited conditions via specific binding to its major transcription initiation site.

Ammonium assimilation is catalyzed by two enzymatic pathways, i.e., glutamine synthetase/glutamate synthase (GS/GOGAT) and alanine dehydrogenase (AlaDH) in Amycolatopsis mediterranei U32. Under nitrogen-rich conditions, the AlaDH pathway is the major route for ammonium assimilation, while the GS/GOGAT pathway takes over when the extracellular nitrogen supply is limited. The global nitrogen regulator GlnR was previously characterized to activate the transcription of the GS encoding gene glnA in response to nitrogen limitation and is demonstrated in this study as a repressor for the transcription of the AlaDH encoding gene ald, whose regulation is consistent with the switch of the ammonium assimilation pathways from AlaDH to GS/GOGAT responding to nitrogen limitation. Three transcription initiation sites (TISs) of ald were determined with primer extension assay, among which transcription from aldP2 contributed the major transcripts under nitrogen-rich conditions but was repressed to an undetectable level in response to nitrogen limitation. Through DNase I footprinting assay, two separate regions were found to be protected by GlnR within ald promoter, within which three GlnR binding sites (a1, b1 sites in region I and a2 site in region II) were defined. Interestingly, the major TIS aldP2 is located in the middle of a2 site within region II. Therefore, one may easily conclude that GlnR represses the transcription of ald via specific binding to the GlnR binding sites, which obviously blocks the transcription initiation from aldP2 and therefore reduces ald transcripts.

Stable atomic structure of NiTi austenite

Nitinol (NiTi), the most widely used shape-memory alloy, exhibits an austenite phase that has yet to be identified. The usually assumed austenite structure is cubic B2, which has imaginary phonon modes, hence it is unstable. We suggest a stable austenite structure that on average has B2 symmetry (observed by X-ray and neutron diffraction), but exhibits finite atomic displacements from the ideal B2 sites. The proposed structure has a phonon spectrum that agrees with that from neutron scattering, has diffraction spectra in agreement with XRD, and has an energy relative to the ground state that agrees with calorimetry data.

Structural Changes of Li2MoO3 As Cathode Material for Li-Ion Batteries during Initial Charge-Discharge Studied By Synchrotron-Based X-Ray Diffraction and Absorption

Introduction James and Goodenough first introduced layer-structured Li2MoO3 as a lithium-battery cathode material [1]. It has a disordered NaFeO2 structure (; a = 2.884 Å, c = 14.834 Å) consisting of a cubic close-packed oxygen cations with basal planes of octahedral sites alternatively filled with Li ions (3a sites) and a randomly distributed mixture of 1/3 Li (3b sites) and 2/3 Mo (3b sites) forming a Li-Mo layer(with a 1:2 Li:Mo ratio), in which the Mo ions forming disordered Mo3O13 clusters rather than isolated Mo ions.[1-5] The theoretical capacity of the Li2MoO3 reaches 339 mAh g-1 based on the Mo4+/Mo6+ redox reaction alone (i.e. without oxidation of the O2- anions) and the Mo4+/Mo6+ redox reaction potential is much lower than that of the oxygen release in Li2MnO3. Therefore, Li2MoO3 is expected to be a good component in building a new layer-structured xLi2MoO3·(1-x)Li M O2 system as high-capacity cathode materials. Here we report the structural studies and charge compensation of Li2MoO3 during the initial charge and discharge. The close to fully reversible structural changes and Mo ion migration, originated from the charge compensation of Mo ions in both the Mo-O and Mo-Mo covalent bonds in the Mo3O13 cluster, make the Li2MoO3 an appropriate alternative of Li2MnO3 in constructing new xLi2MoO3·(1-x)Li M O2 cathode materials, which have less irreversible transition metal migration and oxygen evolution. The findings in this work will also shed light on the fundamental understandings of the relationships between the performance and structure changes, as well as on the new approaches in developing lithium-rich cathode materials with both high energy density and long cycle life. Results and discussion To understand the structural changes of Li2MoO3 during lithium extraction, in situ x-ray diffraction (XRD) and X-ray absorption (XAS) spectroscopy at Mo K-edge were used to study the crystal structure and valence state as well as local structural changes of Mo ions in charging process. The X-ray absorption near edge structure (XANES) spectra of the Mo K-edge during charge show a continuous increase of the pre-edge peaks indicates the increased distortion of Mo-O6 octahedral. The white line of the K-edge shifted to the higher energy gradually, suggesting the increasing oxidation state of Mo ions upon charge. Compare with the Mo K-edge XANES data of the MoO2 and MoO3 references, it can be estimated that the Mo ions were oxidized from Mo4+ to average oxidation state close to Mo6+. More detailed results will be discussed in the presentation. Acknowledgement This work was supported by the U.S. Department of Energy, the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies under Contract No. DE-AC02-98CH10886. Use of the National Synchrotron Light Source was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886. The work at Institute of Physics, Chinese Academy of Sciences was supported by the National Natural Science Foundation (No. 51372268) of China and the National 973 Program of China (2009CB 220100).

Atomic structure of Li2-xMnO3studied by neutron diffraction and STEM

Li2MnO3 is an important cathode material with extra high capacity (&gt;300mAh g-1 for the first charge process). The exact charge-discharge mechanism and the structure evolution still remain controversial. Here the atomic structures of Li2MnO3 after partial delithiation and lithiation are investigated by neutron powder diffraction and spherical aberration-corrected scanning transmission electron microscopy (STEM). Neutron diffraction experiments are performed on Li2-xMnO3 (x=0, 0.25) in a bulk level. It can be found that the volume of the unit cell almost keeps constant, while the lattice constants in the a, b direction increases after the chemical delithiation, but the c direction decreases. For the delithiated compound Li1.75MnO3, the Li occupancies are 0.7(+-0.3), 0.9(+-0.1) for the 2c and 4h sites, respectively, resulting in the Li-concentration of 1.75(+-0.27), while the 2b sites are fully occupied. Furhtermore, the isotropic thermal vibration factors of the 2c and 4h Li atoms are considerably larger than that of the 2b Li atoms, also seemingly implying the feasible delithiation of Li atoms at the 2c and 4h sites in the Li-O layer. It is interesting to note that the thermal factor of Mn atoms is slightly larger than O atoms, which probably means that the Mn atoms are more mobile than O atoms. The STEM results suggest that the Li ions can be extracted both from the LiMn2 planes and Li planes, and the Mn ions can move reversibly in the (110) plane during delithiation and lithiation.

Electrochemical Activity and Li-Disordering of Li2MnO3 by Coexisting with CuO

For many years, challenges to develop lithium ion secondary batteries with high energy density have been extensively investigated. Li2MnO3-based positive electrodes such as LiNi1/3Mn1/3Co1/3O2 have attractive cell performances which are suitable for the electrical vehicles using lithium ion batteries. These materials include a large amount of Li which is essential for large capacity as a positive electrode. However, Li2MnO3 itself without Co or Ni has a poor electrochemical activity except for those of prepared at lower temperatures such as 773 K. Recently, we have found out the way to activate Li2MnO3 electrochemically by coexisting with CuO, not by substitution [1]. We try to clarify the reason why the existence of CuO induces the electrochemical activity of Li2MnO3 focusing on the crystal structure by SR-XRD, XAFS and ab-initiocalculation. In addition, a positive material with new composition exhibiting good electrochemical performance will be presented. EXPERIMENTAL The samples were prepared by combining coprecipitation and solid state reaction. The compositions of them are x = 1/5, 1/4, 3/8, 1/2 in (1-x)Li2MnO3-xCuO respectively. After dissolving CuSO4 and Mn(CH3COO)2 into the distilled water, the co-precipitates were obtained by changing pH from 10 to 12. Dry precipitates and LiOH·H2O were mixed and after calcination at 743 K, sintered at 973 K for 12hr under O2 flow. Electrochemical testing was carried out using coin-type cells with Li/1M LiPF6 in EC:DMC(3:7)/samples. X-ray diffraction (XRD) measurements using both CuKα radiation and a synchrotron radiation source were performed and for the latter on BL02B2 and BL19B2 at SPring-8. Structural refinements were carried out by Rietveld analysis using the RIETAN-FP program[2]. X-ray absorption measurements of above samples at the Mn and Cu K-edges by transmission method were performed on BL14B2 at SPring8. The first principle calculations were carried out using the WIEN2k and VASP program packages. RESULTS AND DISCUSSIONS To clarify the reason why coexisitng with CuO enhances the electrochemical activity of Li2MnO3, at first we fouced on the crystal structure of Li2MnO3 and carried out Rietveld analysis using SR-XRD for all the investigated samples, based on the structural model of monoclinic Li2MnO3, S.G. C2/m. It was found that Li and Mn locate on both 2b and 4g sites of Wyckoff positions. A disordering of Li and Mn in the structure of Li2MnO3 increased by CuO contents. The results of neutron diffraction patterns supports those of XRD. These disordering behaviour probably may correlate closely with the electrochemical activity of Li2MnO3. In addition, a significnat difference of electron diffraction patterns was observed between x = 1/5 which showed discharge capacity of 160 mAhg-1 and x = 1/2 that of 355 mAhg-1. A distinguished streaks along c* axis appeared for x = 1/2 suggesting a stacking fault, wheares some diffraction spots did for x = 1/5. A similar results for Li(Ni, Mn, Co)O2 are rescribed in ref. [3]. The coexsisting with CuO intoroduce a stacking fault into Li2MnO3. Next, we considered an effect of partial substiontion of Cu. The ab-initio electronic structure calculation allows us to know more about the electrical property. Density of States (DOS) of our assumed supercell, Li16(Mn7Cu1)O24 indicated a new sharp band which expect to show higher electrical conductivity than that of Li2MnO3 itself. Hence, the partial replacing Mn by Cu suggests an improvement of the electrochemical property. Next, we focused on CuO coexisting with Li2MnO3. Whereas a pure CuO is an insulator, Li-doped CuO could be a semiconductor. Therefore, it is reasonable that the kinetic barrier of the electrode reaction for Li2MnO3was depressed by coexisting with CuO.We will present a new way to activate Li2MnO3 electrochemically by coexisting CuO, not by substitution and discuss the mechanism why coexisitng with CuO enhances the electrochemical activity of Li2MnO3based on both experimental and calculation results. A CKNOWLEDGEMENT This research was supported by Japan Society for the Promotion of Science (25410255). REFERENCES 1 Y. Arachi, K. Hinoshita and Y. Nakata, ECS Transactions, 41(29), 1-7(2012).2 F. Izumi and K. Momma, Solid State Phenom., 130, 15-20(2007).3 A. Boulineau, L. Croguennec, C. Delmas, F. Weill, Solid State Ionics., 29, 1652 -1659(2010).

Kinetics and structural changes of Li-rich layered oxide 0.5Li2MnO3·0.5LiNi(0.292)Co(0.375)Mn(0.333)O2 material investigated by a novel technique combining in situ XRD and a multipotential step.

Li-rich layered oxide 0.5Li2MnO3·0.5LiNi0.292Co0.375Mn0.333O2 was prepared by an aqueous solution-evaporation route. X-ray powder diffraction (XRD) showed that the as-synthesized material was a solid solution consisting of layered α-NaFeO2-type LiMO2 (M = Ni, Co, Mn) and monoclinic Li2MnO3. The superlattice spots in the selected area electron diffraction pattern indicated the ordering of lithium ions with transition metal (TM) ions in TM layers in this Li-rich layered oxide. Electrochemical performance testing showed that the as-synthesized material could deliver an initial discharge capacity of 267.7 mAh/g, with a capacity retention of 88.5% after 33 cycles. A new combination technique, multipotential step in situ XRD (MPS in situ XRD) measurement, was applied for the first time to investigate the Li-rich layered oxide. Using this approach, the relationships between kinetics and structural variations can be obtained simutaneously. In situ XRD results showed that the c parameter decreased from 3.70 to 4.30 V and increased from 4.30 to 4.70 V, whereas the a parameter underwent a decrease above 4.30 V during the first charge process. Below 3.90 V during the first discharge process, a slight decrease in the c parameter was found along with an increase in the a parameter. During the first charge process, the value of the coefficient of diffusion for lithium ions (DLi+) decreased to its mininum at 4.55 V, which might be associated with Ni(2+) migration, as indicated by both Ni occupancy in 3b sites (Ni3b%) in the Li(+) layers and complicated chemical reactions. Remarkably, a lattice distortion might occur within the local domain in the host stucture during the first discharge process, indicated by a slight splitting of the (003) diffraction peak at 3.20 V.