- Large-scale, surfactant-free, hydrothermal synthesis of lithium aluminate nanorods: Optimization of parameters and investigation of growth mechanism
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Lithium aluminate nanorods were successfully synthesized from Al 2O3 nanoparticles and lithium hydroxide by a simple, large-scale hydrothermal process without any surfactant or template. The various reaction parameters were optimized to achieve the maximum yield. The as-obtained nanorods had orthorhombic β-lithium aluminate structure with edges in the range of 40-200 nm and lengths of 1-2 μm confirmed by SEM, TEM, XRD, and NMR. Upon calcination at 1273 K for 12 h it transformed to γ-lithium aluminate, yet maintained the initial morphology, demonstrating the thermal stability. The ratio of lithium hydroxide to aluminum oxide showed a significant effect on the morphology as Li/Al = 1 gives microroses , whereas Li/Al = 3 and Li/Al = 15 gave microbricks and nanorods , respectively. Investigation of the mechanism showed that the nanorods were formed via a rolling-up mechanism. As we used all-inorganic raw materials and a simple synthetic procedure under mild conditions, the scale-up of this process for large-scale production should be very easy.
- Joshi, Upendra A.,Jae, Sung Lee
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- The influences of heat treatment on the structural properties of lithium aluminates
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Two synthesis routes, sol precipitation and sol gelation, using aluminum isopropoxide and lithium nitrate as precursors have been used to prepare lithium aluminate. The sol precipitation method (LISOL) produced a mixture of γ-LiAlO2 and LiAl5O8, and sol gelation (LIGEL) produced pure γ-LiAlO2, both at 750°C. The density and specific surface area of the ceramic powders calcined at 1150°C were 2.72 g cm-3 and 6 m2 g-1, respectively, for the powders obtained by sol precipitation and 2.47 g cm-3 and 2 m2 g-1, respectively, for the powders obtained by sol gelation. The synthesized powders presented thermal stability over 600°C and the sintering process occurred in the temperature range of 600-1400°C. The absorbed heat by the material in this temperature range during DTA/TG experiment showed that the sintering process was more efficient when the powders were previously calcined over 550°C.
- Ribeiro,Silva,Mohallem
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- Cation coordination and Fe3+ luminescence in LiAlO2 polymorphs prepared by a hydrothermal method
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The polymorphs α-, β-, and γ-LiAlO2 were synthesized by a hydrothermal method. The as-prepared product obtained at 240 °C was β-LiAlO2, which converted completely to γ-LiAlO2 above 1000 °C. α-LiAlO2 was obtained by the decomposition of LiAl(OH)4·H2O prepared by imbibition of LiOH into LiAl2(OH)7·2H2O hydrothermally at 140 °C. Solid state MAS NMR (magic-angle spinning nuclear magnetic resonance) studies indicate that Li+ uniquely occupies octahedral sites in all the polymorphs. This observation indicates that the results of XRD and crystal structure studies on β- and γ-LiAlO2 reported in the literature that indicate the presence of Li- in the tetrahedral site are apparently in error with respect to Li+ coordination. The other cation, Al3+, occupied octahedral sites in α-LiAlO2 and tetrahedral sites in the β- and γ-LiAlO2. The Fe3+ doped in the various polymorphic forms of this compound was found to uniquely occupy the octahedral Li+ site. EPR spectrum of the Fe3+ doped in these polymorphs indicates that during the transformation this site is distorted. The Fe3+ photoluminescent emission maximum was different for each polymorph. The difference in the luminescence characteristics among the polymorphic forms is due to the change in the site symmetry because of the distortion of the octahedra occupied by Fe3+ across the phase transition. The infrared spectrum indicates that site symmetry is lowered during the phase transition.
- Kutty,Nayak
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- Impact of the memory effect on the catalytic activity of Li-Al hydrotalcite-like compounds for the cyanoethylation reaction
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The target of this work is to investigate structural and textural modifications of Li-Al hydrotalcite-like compounds by memory effect and their impact on the catalytic activity of these solids for the cyanoethylation reaction. The samples have been characterized by XRD, FT-IR, TG-DTG, surface area and porous structure. The catalytic test results showed that the reconstruction of the hydrotalcite leads to a decrease of the catalytic activity compared to the parent hydrotalcite. This fact may be related either to the smaller specific surface area of the reconstructed form or to the leaching of Li+ during reconstruction. It has been also noticed that the calcination of Li-Al hydrotalcite leads to the formation of a α-LiAlO 2 stable phase.
- Pavel,Zvoianu,B?rjega,Angelescu
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- Thermochemical capture of carbon dioxide on lithium aluminates (LiAlO 2 and Li5AlO4): A new option for the CO 2 absorption
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Lithium aluminates (LiAlO2 and Li5AlO4) were synthesized, characterized, and tested as possible CO2 captors. LiAlO2 did not seem to have good qualities for the CO2 absorption. On the contra
- Avalos-Rendon, Tatiana,Casa-Madrid, Julio,Pfeiffer, Heriberte
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- Local Coordination of Low-Spin Ni3+ Probes in Trigonal LiAl yCo1-yO2 Monitored by HF-EPR
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The local coordination of low-spin Ni3+ probes in trigonal LiAlyCo1-yO2 was studied using high-frequency EPR spectroscopy. This technique allows distinguishing between two types of Ni3+ ions: Ni3+ ions in trigonal crystal field ( 2Eg ground state) and Ni3+ ions in tetragonal crystal field (2A1g ground state). When a Ni3+ ion is in a uniform Co environment, the orbitally degenerate state for Ni 3+ is preserved and the EPR spectrum of the ground vibronic doublet state can be observed (intermediate Jahn-Teller effect). The value of g 1 decreases as the mean M - O bond is contracted. The local tetragonal distortion can be observed for Ni3+ ions located in a mixed Co6-yAly environment. Along the progressive replacement of Co by Al, the strength of the crystal field for Ni3+ increases gradually and the extent of the tetragonal distortion displays a tendency to increase. The maximum effect of Jahn-Teller distortion is achieved when the Ni3+ ion falls in a pure Al environment.
- Stoyanova, Radostina,Zhecheva, Ekaterina,Alcántara, Ricardo,Tirado, José L.
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- Subsolidus phase relations in the Al2O3-Li 2O-Ta2O5 (Nb2O5) systems
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The phase composition has been studied and an equilibrium phase diagram has been designed for the Al2O3-Li2O-R 2O5 (R = Ta or Nb) systems in the subsolidus region up to 1000°C and 85 mol % Li2/s
- Zuev
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- Metal nitrate/fuel mixture reactivity and its influence on the solution combustion synthesis of γ-LiAlO2
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The reactivity of LiNO3 and Al(NO3)3 with respect to urea and β-alanine was investigated. Experimental results proved that β-alanine is a more suitable fuel for LiNO3, whereas urea seems to be more adequate for
- Iano?, Robert,Laz?u, Ioan,P?curariu, Cornelia
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- Hydrothermal routes to various controllable morphologies of nanostructural lithium aluminate
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The α-LiAlO2 powders have been successfully prepared by a hydrothermal route based on using the surfactant of heax-adecyltrimethyl ammonium bromide (CTAB) as the template. One-dimensional (1D) nanorods with higher and lower aspect ratio, 2D mesoporous microsheets were respectively observed with different concentration of the surfactants. A high specific surface area up to 151 m2/g was obtained by this method. The formation mechanism of the nanostructural lithium aluminate was proposed.
- Hu, Linfeng,Qiao, Bin,Tang, Zilong,Zhang, Zhongtai
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- Sol-gel synthesis of lithium aluminate
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LiAlO2 was prepared by two sol-gel methods using simultaneous hydrolysis of the reagents: aluminum sec-butoxide/ lithium methoxide and aluminum sec-butoxide/LiOH. The resulting ceramic powders were compared with those prepared by two conventional methods (i.e., solid-state fusion and peroxide). The sol-gel method provided powders with a very high γ-LiAlO2 content after calcining at temperatures as low as 700°C when LiOH was used. The solids were characterized by AAS, DTA, TGA, XRD, and SEM.
- Valenzuela, Miguel A.,Jimenez-Becerril, Jaime,Bosch, Pedro,Bulbulian, Silvia,Lara, Victor H.
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- Interaction of x-ray amorphous aluminum oxide with lithium carbonate: Effect of the chemical history of aluminum oxide
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The high-temperature (950-1050°C) crystallization behavior of x-ray amorphous Al2O3 and its reaction with lithium carbonate in the range 500-700°C were studied using Al2O3 samples prepared by five different procedures: thermal decomposition of Al(NO 3)3·9H2O, Al2(C 2O4)3·nH2O, aluminum hydroxides synthesized via Al3+ precipitation from aluminum nitrate and aluminum chloride solutions by a 20% excess of a concentrated NH 4OH solution, and sol-gel-prepared aluminum hydroxide. The results demonstrate that the preparation procedure has a significant effect on the crystallization behavior and solid-state reactivity of x-ray amorphous aluminum oxide.
- Sinitskii,Oleinikov,Murav'eva,Tret'yakov
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- CRYSTAL GROWTH OF ROD-SHAPED beta -LiAlO2.
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The use of fuel cells is a highly effective method of generating electric power. For this application, LiAlO//2 crystals, which are inert against alkali carbonate, are desirable as a reinforcement material. LiAlO//2 crystals are obtained conventionally in the form of powder. In a few publications, crystal growth of rod-shaped LiAlO//2 has been described, but the fiber length was very short, less than 4 mu m. In the present study, rod-shaped beta -LiAlO//2 crystals 10 to 15 mu m long were grown using LiOH-Al//2O//3-NaOH as the raw material.
- Watanabe,Takeuchi,Saeki
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- A study on the start-up and performance of a kW-class molten carbonate fuel cell (MCFC) stack
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A kW-class internal-manifolded molten carbonate fuel cell (MCFC) stack (52 cells) was assembled with inorganic adhesive under a suitable stacking pressure. The organic compounds in the matrices were burnt out under the conditions of slow and uniform elevation of temperature and big flow of oxygen gas in the stack. The stacking pressure dropped with elevating temperature. The output power of the stack at 150 mA cm-2 was 1025.5 W when the reactant gas pressure and utilization were 0.5 MPa and 20%, respectively. The thermal-electrical efficiency of the stack was enhanced by increasing the pressure of the reactant. However, it was contrarily decreased when current density was increased.
- Zhou, Li,Lin, Huaxin,Yi, Baolian,Zhang, Huamin,Shao, Zhigang,Ming, Pingwen,Cheng, Mojie
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- Thermal evolution of the CI--LiAl2 layered double hydroxide: A multinuclear MAS NMR and XRD perspective
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Layered double hydroxides (LDHs) with a cation composition of LiAl2 have a wide range of potential applications as catalysts, catalyst supports, and precursors for refractory oxide materials, including several industrially important lithium aluminate phases. The understanding of the calcination behavior of this group of LDH phases is essential to advancing these applications, and the research described here focuses on the thermal decomposition and structural evolution of LiAl2(OH)6Cl·nH2O in the temperature range of 20-1100 °C. 27Al, 35Cl, and 6.7Li magic angle spinning nuclear magnetic resonance spectroscopy, powder X-ray diffraction, thermal analysis (including thermogravimetric and differential scanning calorimetry), and compositional analysis provide a highly consistent picture of the thermally induced phase formation and transformations of this LDH. The loss of the surface and interlayer water can begin as low as room temperature, depending on the relative humidity. Beginning at about 300 °C, the simultaneous volatilization of H2O and HCl and the exsolution of crystalline LiCl result in the formation of amorphous Li-Al-O-OH. By at least 500 °C, volumes with the structures of α-LiAlO2 and LiAl5O8 appear, and these phases become progressively more ordered with increasing temperature. LiCl begins to volatilize by 850 °C and is present only in trace amounts above ca. 1000 °C. α-LiAlO2 converts to γ-LiAlO2 between 970 and 1100 °C. Because of the delithiation due to LiCl volatilization, the final products are dominated by LiAl5O8, in contrast to the calcination products of previously studied LiAl2 LDHs which are dominated by LiAIO2.
- Hou,Kirkpatrick
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- Surfactant-free hydrothermal synthesis of lithium aluminate microbricks and nanorods from aluminium oxide nanoparticles
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β-LiAlO2 microbricks and rectangular nanorods have been successfully synthesized from Al2O3 nanoparticles by a simple hydrothermal process without any surfactant or template, by simply changing the Li/Al molar ratio. The Royal Society of Chemistry 2005.
- Joshi, Upendra A.,Chung, Soo Hyun,Lee, Jae Sung
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- ELECTRICAL CONDUCTIVITY OF POLYCRYSTALLINE Li2SiO3 AND gamma -LiAlO2.
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Some lithium compounds have been studied as potential electrolyte materials. Electrical conductivities of lithium silicate and aluminate were measured in the temperature range of 450 to 1000C. Intrinsic and extrinsic regions were observed. The activation
- Konishi,Ohno
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- Synergistic use of Knudsen effusion quadrupole mass spectrometry, solid-state galvanic cell and differential scanning calorimetry for thermodynamic studies on lithium aluminates
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Three ternary oxides LiAl5O8(s), LiAlO2(s) and Li5AlO4(s) in the system Li-Al-O were prepared by solid-state reaction route and characterized by X-ray powder diffraction method. Equilibrium partial pr
- Rakshit,Naik,Parida,Dash, Smruti,Singh, Ziley,Sen,Venugopal
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- Effect of Al(OH)3 addition on β-LiAlO2 crystal growth
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Crystal growth of rod-shaped β-LiAlO2 was previously reported by us, and the rod-shaped β-LiAlO2 crystals were 1.5 μm in diameter and 10 to 15 μm long. In the present study needle-shaped β-LiAlO2 crystals which were thinne
- Watanabe,Takeuchi,Saeki
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- Note on the Li-Cu-O system
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In the Li-Cu-O system two new ternary phases have been found, tentatively described by the stoichiometries LiCu3O3 and LiCu2O2, and both containing Cu1 and Cu11. They exhibit p-type 'hopping' conduction owing to localized charge carriers. Their powder patterns are successfully indexed on high-symmetry cells where the dimensions depend on a slightly variable stoichiometry. LiCu3O3 is tetragonal with a = 2.815 (·√2) angstrom and c = 8.88 angstrom. LiCu2O2 is orthorhombic with a = 5.72 angstrom, b = 2.86 angstrom and c = 12.4 angstrom. Li3Cu2O4, containing Cu11 and Cu111, is indexed on a C-centred monoclinic cell: a = 9.958 angstrom, b = 2.777, c = 7.281 angstrom and β = 118.77°. The solubility of lithium in CuO is maximally Li0.06Cu0.94O for supersaturation at 1100 K. The equilibrium solubility limit is about Li0.02Cu0.98O, for which the solid solution is still semiconducting. The temperature dependence of the magnetic susceptibility is similar to that of pure CuO but TN is considerably lower.
- Berger R.
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- A LiAlO2/nitrogen-doped hollow carbon spheres (NdHCSs) modified separator for advanced lithium-sulfur batteries
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Lithium-sulfur (Li-S) batteries have gained significant attention due to their ultrahigh theoretical specific capacity and energy density. However, their practical commercialization is still facing many intractable problems, of which the most difficult is the shuttle effect of dissolved polysulfides. To restrict the shuttle of polysulfides, herein, a novel double-layer lithium aluminate/nitrogen-doped hollow carbon sphere (LiAlO2/NdHCSs)-modified separator was designed. The upper NdHCSs layer on the separator works as the first barrier to physically and chemically adsorb polysulfides, whereas the bottom LiAlO2 layer acts as the second barrier to physically block the polysulfides without restricting the Li+ transport due to the high ionic conductivity of LiAlO2. Cells with the LiAlO2/NdHCSs-modified separator showed an initial discharge capacity of 1500 mA h g-1 at 0.2C, and a discharge capacity of 543.3 mA h g-1 was obtained after 500 cycles at 2C. Especially, when the areal density of the active material was increased to 4.5 mg cm-2, the cells retained a discharge capacity of 538.6 mA h g-1 after 100 cycles at 0.5C. The outstanding electrochemical performance of Li-S cells with the LiAlO2/NdHCSs-modified separators show a new approach for the applications of Li-S batteries.
- Li, Fanqun,Qin, Furong,Wang, Guanchao,Zhang, Kai,Wang, Peng,Zhang, Zhian,Lai, Yanqing
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- Effect of synthesis techniques on crystallite size and morphology of lithium aluminate
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γ-LiAlO2 considered as a candidate tritium breeder material for fusion reactors because of its thermophysical, chemical, and mechanical stability at high temperatures and its favorable neutron irradiation behavior. Crystallite size and shape could, however, alter these features. In this study the mean crystallite size, the crystallite size distribution, and the morphology of γ-LiAlO2 are correlated to the synthesis procedure. The characterization techniques were powder X-ray diffraction and scanning electron microscopy.
- Carrera,Jimenez-Becerril,Bosch,Bulbulian
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- Synthesis of Fine-Particle α-LiAlO2 via Heat Treatment of a Mechanically Activated Mixture of Gibbsite and Lithium Carbonate
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Abstract—: We have found conditions for the synthesis of fine-particle phase-pure α-LiAlO2 via heat treatment of a mechanically activated mixture of gibbsite and lithium carbonate in air. The results demonstrate that, to synthesize α-LiAlO2, the mechanical activation of the reaction mixture should cause no gibbsite amorphization and heat treatment in air should be performed in the range 650–700°C.
- Isupov,Borodulina,Niyazova,Eremina
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- Effect of mechanical activation of Al(OH)3 on its reaction with Li2CO3
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The effect of preliminary mechanical activation of Al(OH)3 on its solid-state reaction with Li2CO3 at temperatures above 800°C has been studied by thermogravimetry, X-ray diffraction, in situ X-ray diffraction, electron mi
- Isupov,Eremina
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- Preparation and electrochemical performance of spinel-type compounds Li4Aly,Ti5-yO12 (y = 0, 0.10, 0.15, 0.25)
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Li4Ti5O12 and Al3+ doped Li4AlyTi5-yO12 (y = 0.10, 0.15, 0.25) were synthesized via solid-state reaction using TiO2-rutile, Li2CO3, and Al2O3 as starting reagents. The charge-discharge cycling of the cells showed that the electrochemical performance of Li4Ti5O12 prepared from rutile-type TiO2 by our laboratory was as good as that produced by anatase-type TiO2. However, Al3+ doped Li 4AlyTi5-yO12 (y = 0.10, 0.15) exhibited a much better electrochemical performance in comparison with undoped Li4Ti5O12. Among the three samples of Li 4AlyTi5-yO12 (y = 0, 0.10, 0.15), Li4Al0.15Ti4.85O12 exhibited the largest reversible capacity and the highest coulombic efficiency. The discharge capacity values in the first and second cyclings were 195.6 and 173.6 mAh/g, respectively. The value remained 166.9 mAh/g after 30 cycles with a capacity loss of 3.86% compared to the second cycle, and the coulombic efficiency was 99.2% at the 30th cycle.
- Huang, Shahua,Wen, Zhaoyin,Zhu, Xiujian,Lin, Zuxiang
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- Chemical interaction between LiF and MgAl2O4 spinel during sintering
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Reactions between LiF and MgAl2O4 at temperatures up to 1500°C are examined with a variety of tools, including differential scanning calorimetry, thermo-gravimetric analysis, X-ray diffraction, and scanning electron microscopy. LiAlO2 and MgF2 are found to be the active reaction products at these temperatures. A transient liquid phase comprising MgF2 and LiF forms at intermediate temperatures, but then is consumed at higher temperatures during the reformation of MgAl2O4. If processed as an uncompacted powder mixture, all of the initial LiF in the system eventually vaporizes at temperatures exceeding 1300°C. A new reaction sequence relevant to the densification of LiF-doped MgAl2O4 spinel is proposed.
- Rozenburg,Reimanis,Kleebe,Cook, Ron L.
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- Synthesis and characterization of LiAl 1/4 Ni3/4O2 (R3m) for lithium-ion (shuttlecock) batteries
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The synthesis and characterization of LiAl 1/4 Ni3/4O2 were carried out in order to improve the electrochemical properties of LiNiO2 for lithium ion batteries. Single phase of LiAl 1/4 Ni3/4O2 (R3m; a = 2.86 angstrom and c = 14.24 angstrom in hexagonal setting) was obtained by heating a reaction mixture of LiNO3, NiCO3, and Al(OH)3 at 750°C under an oxygen stream for 20 h and examined in nonaqueous lithium cells. LiAl 1/4 Ni3/4O2 was oxidized to □3/4Li 1/4 Al 1/4 Ni3/4O2 in the voltage range of 3.5-4.8 V. X-ray diffraction examinations of Li1-xAl 1/4 Ni3/4O2 indicated that the reaction LiAl 1/4 Ni3/4O2 ? □3/4Li 1/4 Al 1/4 Ni3/4O2 + (3/4)Li+ + (3/4)e- (ca. 4.75 angstrom of layer separation) (ca. 4.80 angstrom of layer separation) proceeded in a single phase over the entire range. The rechargeable capacity was observed to be about 150 mAh · g-1 based on the sample weight. DSC measurements on fully charged LiNiO2 and LiAl 1/4 Ni3/4O2 at 4.8 V were also done and the effects of substitution of aluminum for nickel in LiNiO2 upon the electrochemical properties were discussed in terms of capacity, failure, and safety coupled with overcharge.
- Ohzuku,Ueda,Kouguchi
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- Solid solution in the LiAlO2-LiCrO2 ternary oxide system
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The solid solution LiAlxCr1-xO2 has been synthesized over the complete range 0 ≤ x ≤ 1. The syntheses at the high alumnium compositions (x ≥ 0.60) have been achieved through stabilization of the α-LiAlO2 structu
- Poeppelmeier,Thong
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- Effect of Al addition on formation of layer-structured LiNiO2
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Kinetics and formation mechanism of undoped and Al-doped LiNiO2 from Li2CO3 and NiO were investigated in this study. Without the addition of Al ions, sluggish kinetics for the formation of undoped LiNiO2 was observed. The fraction of undoped LiNiO2 reached 50% after Li2CO3 and NiO reacted at 700°C for 150 min. With the addition of 25% of Al ion, the fraction of Al-doped LiNiO2 reached 50% within 60min at 700°C. The analysis of kinetics study indicates that the formation of undoped and Al-doped LiNiO2 is a diffusion-controlled process. Furthermore, the rate constant determined from Jander model {[1 - (1 - α)1/3]2 = Kt} was significantly enhanced by the addition of Al. The activation energy for the formation of LiNiO2 drastically decreased from 190k J/mole (undoped reaction) to 83 kJ/mole when 25% Al was added. The enhancement of LiNiO2 formation by Al doping is attributed to the structure resemblance between α-LiAlO2 and LiNiO2. α-LiAlO2 acts as the seeding material which provides nucleation sites for the growth of LiNiO2.
- Lin, Shih-Pin,Fung, Kuan-Zong,Hon, Yi-Ming,Hon, Min-Hsiung
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- Effect of solvents on the preparation of lithium aluminate by sol-gel method
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γ-Lithium aluminate was prepared by sol-gel method using lithium methoxide and aluminum-sec-butoxide precursors in i-propanol, n- and tert-butanol. Clear gels could be obtained due to the addition of ethylacetoacetate and the dried solids were calcined at 550 and 900°C. The resulting solids were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermo-gravimetric analysis/differential thermal analysis (TGA/DTA). γ-Lithium aluminate with the highest purity was obtained with t-butanol solvent and LiAl5O8 was the second major phase.
- Oksuzomer, Faruk,Koc, S. Naci,Boz, Ismail,Gurkaynak, M. Ali
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- Electronic structure and photocatalytic characterization of a novel photocatalyst AgAlO2
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A novel photocatalyst, AgAlO2, was prepared by cation exchange reaction and characterized by powder X-ray diffraction. The result showed AgAlO2 crystallizes in the layered orthorhombic structure with space group was Pna21. The energy band and electronic structures of AgAlO2 were calculated based on the crystal structure. It was found that AgAlO2 is an indirect band gap semiconductor. The valence band top mainly consists of O-2p orbitals and Ag-4d orbitals and the conduction band bottom is mainly constructed of Ag-5s5p orbitals. The band gap of AgAlO 2 was estimated to be about 2.8(1) eV with UV-vis diffuse reflectance spectrometry. The photocatalytic activity of AgAlO2 was characterized by photocatalytically decomposing the dye alizarin red (AR) under visible light irradiation, and AR could be decomposed about 70% under 2 h of visible light irradiation.
- Ouyang, Shuxin,Zhang, Haitao,Li, Dunfang,Yu, Tao,Ye, Jinhua,Zou, Zhigang
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- Reactions in eucryptite-based lithium aluminum silicates
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The reaction sequence to synthesize β-eucryptite, LiAlSiO4, from the raw ingredients SiO2, Li2CO3, and Al2O3 was studied using thermal analysis and X-ray diffraction techniques. Reactions were examined by heating the raw ingredients as two-component and three-component mixtures in air, then cooling for phase analysis. In some cases, cyclic heating was performed to ensure a complete reaction. It was found that a complex sequence of reactions involving several intermediate phases occurs. The single oxides (SiO2 and Al 2O3) react with Li2CO3 to form the binary oxides (Li2Si2O5, Li2SiO 3, and LiAlO2); SiO2 reacts with Li 2CO3 before Al2O3. Subsequently, the binary oxides form ternary oxides (LiAlSi2O6 and LiAlSiO4). Finally, the ternary oxides form the equilibrium product, β-eucryptite (LiAlSiO4). These reactions are discussed in the context of the thermodynamic properties of the various compounds.
- Jochum, Timothy,Reimanis, Ivar
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- FORMATION AND THERMAL DECOMPOSITION OF ALUMINIUM NITROXY COMPOUNDS.
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During the reactions of lithium oxide with aluminum nitride, and of lithium nitride with aluminum oxide, the formation has been observed of a previously unknown compound, of composition Li//2AlNO. The course of its thermal decomposition has also been determined.
- Lapinski, Z.,Podsiadlo, S.
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- Mechanochemical synthesis of fine-particle γ-LiAlO2
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We describe a new approach for the synthesis of fine-particle gamma lithium aluminate, γ-LiAlO2, which involves mechanical activation of mixtures of Al(OH)3 and Li2CO3 and heat treatment of the products. The formation of γ-LiAlO2 was followed using x-ray diffraction, chemical analysis, thermal analysis, IR spectroscopy, and BET specific surface measurements. The specific surface of the synthesized γ-LiAlO2, 10 to 33 m2/g, is large enough for this material to be used as an electrolyte matrix support for molten carbonate fuel cells.
- Kharlamova,Mitrofanova,Isupov
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- Degradation of magnesium aluminum spinel by lithium fluoride sintering aid
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The effect of LiF sintering aid on the degradation of transparent magnesium aluminate spinel during hot-pressing was studied. LiF is used to etch spinel particles during the hot pressing process. The LiF was found to react with the aluminum in the spinel
- Villalobos, Guillermo R.,Sanghera, Jasbinder S.,Aggarwal, Ishwar D.
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- Mechanically Stimulated Thermal Synthesis of Lithium Pentaaluminate from Lithium Carbonate and Aluminum Hydroxide
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It is shown that the phase composition of lithium aluminates formed when aluminum hydroxide in the form of gibbsite interacts with lithium carbonate in their mixture with Al: Li atomic ratio of 5: 1 depends on the duration of a preliminary mechanical activation of the mixture and on the temperature of the subsequent thermal treatment. A thermal treatment of the starting mixture at temperatures exceeding 800°C yields LiAl5O8 with a substantial admixture of α- and γ-LiAlO2. Raising the duration of the mechanical activation to 5 min and more makes it possible to obtain highly dispersed single-phase LiAl5O8 with a specific surface area larger than 20 m2 g–1.
- Isupov,Eremina,Borodulina
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- LITHIUM ION CONDUCTION IN SUBSTITUTED Li//5MO//4, M equals Al, Fe.
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The ionic conductivity of substituted Li//5AlO//4 and Li//5FeO//4 phases was measured by a complex impedance method. The high-temperature beta phase was obtained in quenched Li//5AlO//4 but not in Li//5FeO//4. The Zn-substituted quenched samples form beta
- Esaka, T.,Greenblatt, M.
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- Mechanochemical synthesis of γ-LiAlO2 studied by 6Li and 27Al NMR and synchrotron X-ray diffraction
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The structural transformations accompanying the mechanochemical synthesis of fine-particle γ-LiAlO2 have been studied by 6Li and 27Al NMR and in situ X-ray diffraction. Mechanical activation of a mixture of aluminum hydroxide and lithium carbonate in an AGO-2 planetary mill results not only in size reduction, intermixing, and partial amorphization of the starting materials but also in the mechanochemical synthesis of a carbonate form of aluminum lithium hydroxide. Subsequent heat treatment of the mechanically activated mixture leads to the release of water and carbon dioxide molecules and the formation of an X-ray amorphous phase containing aluminum in octahedral and tetrahedral oxygen coordination. The X-ray amorphous material converts to gamma lithium aluminate through an intermediate phase. Pleiades Publishing, Ltd., 2011.
- Isupov,Kharlamova,Chupakhina,Sharafutdinov,Khabibulin,Lapina
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- Formation of LiAlyNi1-yO2 solid solutions under high and atmospheric pressure
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Three methods were used for the synthesis of LiAlyNi1-yO2 solid solutions with layered crystal structure: citrate and hydroxide precursor methods at atmospheric pressure and high-pressure synthesis in oxygen-rich atmosphere (3 GPa). Structural characterization of the oxides was performed by powder XRD analysis and electron paramagnetic resonance (EPR) spectroscopy. Irrespective of the different preparation techniques used, it was found that LiAlyNi1-yO2 solid solutions can be formed in the limited concentration range of 0 ≤ y ≤ 0.5 and 0.75 ≤ y ≤ 1.0. The unit cell parameter a decreases linearly with the Al content whereas the unit cell parameter c increases sharper as compared to the linear interpolation of the c parameter calculated for the two end compositions LiNiO2 and LiAlO2. In these compositions, aluminum substitutes for Ni in the NiO2-layer, the mean AlyNi1-y-O bond length decreasing. The extent of the trigonal distortion of AlyNi1-yO6 and LiO6-octahedra varies with the aluminum content and depends on the synthesis procedure used. The LiO6-octahedra are more flexible to tolerate the increased trigonal distortion as compared to the AlyNi1-yO6-octahedra. High-pressure synthesis favors the formation of oxides with a higher extent of trigonal distortion of both AlyNi1-yO6 and LiO6-octahedra. From EPR measurements, it was shown that local cationic distribution in LiAlyNi1-yO2 depends on the synthesis temperature. At atmospheric pressure, higher synthesis temperatures promote the reaction of cation mixing between the layers.
- Shinova,Zhecheva,Stoyanova
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- Low-temperature densification of Al-doped Li7La3Zr2O12: a reliable and controllable synthesis of fast-ion conducting garnets
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The application of Li7La3Zr2O12 as a Li+ solid electrolyte is hampered by the lack of a reliable procedure to obtain and densify the fast-ion conducting cubic garnet polymorph. Dense cubic Li7La3Zr2O12-type phases are typically formed as a result of Al-incorporation in an unreliable reaction with the alumina crucible at elevated temperatures of up to 1230 °C. High Al3+-incorporation levels are also believed to hinder the three-dimensional movement of Li+ in these materials. Here, a new, facile hybrid sol-gel solid-state approach has been developed in order to accomplish reliable and controllable synthesis of these phases with low Al-incorporation levels. In this procedure, sol-gel processed solid precursors of Li7La3Zr2O12 and Al2O3 nanosheets are simply mixed using a pestle and mortar and allowed to react at 1100 °C for 3 h to produce dense cubic phases. Fast-ion conducting Al-doped Li7La3Zr2O12 phases with the lowest reported Al3+-content (~0.12 mol per formula unit), total conductivities of ~3 × 104 S cm1, bulk conductivities up to 0.6 mS and ion conduction activation energies as low as 0.27 eV, have been successfully achieved. The ease of lithium diffusion in these materials is attributed to the formation of dense cubic phases with low Al3+ dopant ratios. This approach is applicable to Li7xLa3Zr2xTaxO12 phases and opens up a new synthetic avenue to Li7La3Zr2O12-type materials with greater control over resulting characteristics for energy storage applications.
- El-Shinawi, Hany,Paterson, Gary W.,MacLaren, Donald A.,Cussen, Edmund J.,Corr, Serena A.
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p. 319 - 329
(2016/12/27)
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- Phase transitions of LiAlO2 at high pressure and high temperature
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This work presents a comprehensive study on phase transitions in LiAlO2 system at high pressures and temperatures (0.5-5.0 GPa and 300-1873 K, respectively), as well as the phase stability for polymeric phases of LiAlO2 in the studied P-T space by X-ray diffraction (XRD). Besides the previously described polymorphic hexagonal α-phase, orthorhombic β-phase and tetragonal δ-phase, a possible new phase of LiAlO2 was observed after the tetragonal γ-LiAlO2 sample was treated at 5.0 GPa and 389 K. The stable regimes of these high-pressure phases were defined through the observation of coexistence points of the polymeric phases. Our results revealed that LiAlO2 could experience structural phase transitions from γ-LiAlO2 to its polymorphs at lower pressures and temperatures compared to the reported results. Hexagonal α-LiAlO2 with highly (003) preferential orientation was prepared at 5.0 GPaand 1873 K.
- Lei, Li,He, Duanwei,Zou, Yongtao,Zhang, Wei,Wang, Zhao,et al.
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p. 1810 - 1815
(2009/02/05)
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- Synthetis of α-Lithium Aluminate Fiber and Its Stability in MoltenCarbonate Salt
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The electrolyte matrix of Molten Carbonate Fuel Cells (MCFC) is generally reinforced with a mixture of alumina fibers to provide strength withinthe cell. However, alumina fibers corrode and are changed into lithium aluminate by reaction with lithium carbonate in molten carbonate. Lithiu m aluminate have two crystal structures in molten carbonate, α-phase and γ-phase. It is known that lithium aluminate undergo mutual crystal structure transformations between α- and γ-phase in molten carbonate. Therefore, the stability of electrolyte matrix is lowered. It is reported recently that α-lihtium aluminate is more stable than γ-phase in molten carbonate. We have studied on α-lithium aluminate fiber instead of alumina fiber. We synthesized it at lowtemperature under CO2 atmosphere by the solid state reaction of γ -alumina fiber with lithium carbonate. Further, it was found that α-lithium aluminate fiber was synthesized with keeping fiber structure. The evaluation of stability of this fiber in molten carbonate were performed by comparing with alumina fiber. The mixture of α-lithium aluminate fiber and α-lithium aluminate powder was stable and the crystal structure of this mixture remained α-lithium aluminate. It can be expected that application of α-lithium aluminate fiber instead of alumina fiber improve the stability of the electrolyte matrix for MCFC.
- Takizawa, Koichi,Hagiwara, Akifusa
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- Thermal Dissociation in Air of Aluminum Hydroxide Intercalation Compounds with Transition-Metal EDTA Complexes
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Thermal dissociation in air of aluminum hydroxide intercalation compounds of the general formula [LiAl2(OH)6]2(Medta) · xH2O (where M = Cu2+, Ni2+, Co2+, Zn2+; edta4- is an ethylenediaminetetraacetato anion) was investigated by DTA-TG and X-ray powder diffraction. The ultimate product of calcination at 1200°C is a mixture of oxides: γ-LiAlO2, spinel solid solution, and, in cases of nickel and copper, the transition-metal oxide. Scanning electron microscopy showed that, even after high-temperature treatment, the thermolysis products have a layered morphology similar to the morphology of virgin samples.
- Tarasov,Isupov,Chupakhina
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p. 1659 - 1665
(2008/10/08)
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- Synthesis of lithium dialuminate by salt imbibition
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The synthesis of lithium dialuminate LiAl2(OH)7·2H2O by reaction at room temperature of solid lithium hydroxide, polycrystalline aluminum trihydroxide (bayerite), and water vapor is described. The aluminate prepared by this method has been characterized by chemical analysis, thermogravimetric analysis, infrared spectroscopy, and X-ray powder diffraction and appears to be identical with that prepared by precipitation from supersaturated aluminate solutions or by reaction of lithium salts with freshly precipitated aluminum hydroxide in aqueous solution. All current evidence suggests that the structure of lithium dialuminate is like that of hydrotalcite, [Mg6Al2(OH)16]2+CO3 2-·4H2O, with neutral dioctahedral sheets of bayerite converted to positively charged trioctahedral layers by incorporation of lithium ion. Hydroxide ion and two water molecules reside between the layers and presumably approximate a plane of oxygen atoms stabilized by hydrogen bonding, as evidenced by a 2.81 (1) A? increase in the bayerite lattice perpendicular to the dioctahedral layer. A more descriptive chemical formula for lithium dialuminate would be [LiAl2(OH)6]+OH-·2H 2O. The imbibition of other lithium salts (LiX; X = Cl-, Br-, I-, NO3-) was also studied. Thermal decomposition results in compounds, related to the transitional aluminas, with high specific surface area and porosity.
- Poeppelmeier,Hwu
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p. 3297 - 3302
(2008/10/08)
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- REACTIONS IN THE Al2O3-NaOH-LiOH SYSTEM.
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Nonisothermal derivatography and X-ray phase analysis are used to investigate the kinetics of conversions of aluminum oxide in mixtures with sodium and lithium hydroxides. It is shown that in ternary Al//2O//3-NaOH-LiOH mixtures the reactions of formation of alkali aluminates take place separately: sodium aluminate is formed over 140 degree , and lithium aluminate over 300 degree . In Al//2O//3-NaOH and Al//2O//3-LiOH binary mixtures the kinetics of the reactions are described by the Hinstling-Braunstein equation. A model of the reaction of the oxide with the two reactants is discussed.
- Dmitruk,Yashchenko
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