Aluminium coordination in LiNi1−yAlyO2 solid solutions (original) (raw)
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Crystal Structure of Lithium-Sodium (Li0.7Na0.3)Analcime
Journal of Structural Chemistry, 2001
When Na is substituted by Li in the narrow-pore zeolite analcime Na 2 [Al 2 Si 4 O 12 ]⋅2H 2 O, the average parameter of the pseudocubic unit cell decreases from 13.67 Å in the starting Na-analcime to 13.50 Å in Li-analcime. Our structural data for Li-analcime [1] showed that the Li cations lie near the Na-sites in an octahedral arrangement O 4 (H 2 O) 2 distorted to 4+2 or 3+3. Due to their smaller size, the Li cations are displaced toward the edge of one of the two Si,Al-tetrahedra coordination-linked to the given site, and the symmetry is reduced from Ibca to Pbca.
Crystal-Chemical Study of Layered [Al2Li(OH)6]+X− · nH2O
Clays and Clay Minerals, 1982
A layered double hydroxide with a chemical composition [A12Li(OH)6]+X 9 nH20, where X is an interlayer anion, has been synthesized hydrothermally at 130~ from aluminum-tri-(sec-butoxide) and lithium carbonate. Electron micrographs showed the product to have a platy morphology with distinct hexagonal symmetry, which has been corroborated by selected area electron diffraction patterns corresponding to a projection of the structure on its (001) plane. Evidence for a superlattice with a = 5.32/~ was obtained, indicating cation ordering among octahedral sites. X-ray powder diffraction data also can be interpreted by reference to a hexagonal supercell with dimensions a = 5.32/~ and c = 15.24/~. The arrangement of the octahedral sites appears to be that of gibbsite, but with the vacancies filled with lithium cations. Anions must be present between the sheets to balance the charge. A complete assignment of the observed infrared lattice vibrations can be made for the anion [AlzLiOt] with the ideal D3d symmetry for motions within one octahedral sheet. The results show that [A12Li(OH)tl+X --nH20 is a hydrotalcite-like compound with the octahedral cations largely ordered. The general formula for hydrotalcite-like compounds, [M2+i_xM3+x(OH)2]x+xm-x/m. nH20, should be extended to include the monovalent lithium cation.
Journal of Structural Chemistry, 2005
The dehydrated form of (Li,Na)-substituted analcime, Li1.30Na0.53[Al1.83Si4.17O12], has been prepared and investigated with single crystal X-ray diffraction: a = 32.167(6) Å, b = 18.551(2) Å, c = 11.693(2) Å; β = 90.06(1)°, V = 6978(1) Å3, Z = 24, space group C2. The structure was analyzed through considering the aluminosilicate framework as a system of tubes composed from corrugated 6-membered rings joint by triples of tetrahedra. Volume decrease by 6.5% and trigonal distortion of the structure are explained by the localization of the non-framework cations in new unusual positions. On dehydration of Li, Na-analcime, 67% of Na+ and 20% of Li+ migrated from the standard M-positions at the periphery of the tubes into essentially different positions NaW and LiL situated on the axes of the tubes. Among the total of the fixed tube positions— 12NaW and 16LiL — one half is aggregated in the tubes parallel to [001] and has a planar three-fold coordination by framework O-atoms. The configuration and cation population of the tubes in other directions follow the motif of the “basic” system.
Inorg Chem, 1995
[(ArO)2(THF)Y@-OAr)]2 (Ar = C&Me2-2,6) reacts with &Me6 or AlEt3 in toluene or hexanes to form the mixed-metal products (Aro)2(THF)2Y@-OAr)2AlR2 [R-Me (l), Et (2)]. These complexes can be obtained in quantitative yield from [AlR2(0Ar)]2 and Y(OAr)3(THF)3 in toluene. Yb and Nd analogs of 1 and 2 can be obtained similarly, and the representative complexes (Ar0)2(THF)2Yb@-OAr)2AlMez, 3, and (Aro)z(THF)zNd-@-OAr)#JEtz, 4, were crystallographically characterized. Complexes 1-4 all crystallize from benzene in the same space group C2k. Unit cell parameters at 298 K follow: 1, a = 24.148(3) A, b = 12.396(3) A, c = 18.677(2) A, p = 118.68(8)', V = 4704(1) A3, 2 = 4; 2, a = 21.790 A, b = 13.039 A, c = 19.434 A, p = 111.68", V = 5128 A3; 3, a = 23.881(9) A, b = 12.035(7) A, c = 18.676(6) A,p = 118.74(2)", V = 4706(3) A3, Z = 4; 4, a = 23.185(2) A, b = 13.128(1) A, c = 18.905(2) A, p = 117.65(1)", V = 5096(1) A3, 2 = 4. In the case of 3, least-squares refinement of the model based on 2500 reflections (IFo[ > 4.00(lF01)) converged to a final RF = 7.6%. For 4 the model based on 2243 reflections (IFo[ > 4.0a(lFoI)) converged to a final RF = 7.2%. Complexes 1, 3, and 4 have distorted octahedral and tetrahedral coordination environments around lanthanide and aluminum, respectively. Supplementary Material Available: Listings of crystal data, data collection, solution, and refinement parameters, atomic coordinates, thermal parameters, and interatomic distances and angles and additional structural diagrams (27 pages). Ordering information is given on any current masthead page.
The Al3+ stabilized phase Li3−3xAlxBO3
Journal of Solid State Chemistry, 2005
The structure of an Al 3+ stabilized phase Li 3À3x Al x BO 3 (x % 0:18) was determined by means of single crystal X-ray diffraction. This phase crystallizes in space group P6 1 22 or P6 5 22, with lattice constants a ¼ 4:9019ð5Þ (A; c ¼ 17:538ð2Þ (A and Z ¼ 6: The unit cell consists of six layers of BO 3 groups with Li + cations distributing statistically on five crystallographic sites, none of which is fully occupied. The Li sites are close to each other and a three-dimensional network results when Li sites only within 1.65 Å are connected. Significant ionic conductivity was observed for this phase.
Solid solutions with rock salt related structures on the join Li2TiO3-Li3NbO4
Journal of Materials Science Letters, 1984
A considerable variety of complex oxides have crystal structures related to that of rock salt, NaC1 and many form both ordered and disordered polymorphs. The disordered polymorphs have the face centred cubic structure of NaC1 in which the cations are distributed at random over the octahedral sites in a cubic close packed array of oxygens. Examples are LiFeO2 [1], Li3NbO4, Li3TaO4 [2], Li2TiO3 [3] and Na2TiO3 [4]. In the ordered polymorphs, different cation ordering sequences are possible, as in, for example, tetragonal LiFeO2 [1], rhombohedral NaA102 [5], monoclinic Li2TiO3 [3, 6], monoclinic Li2ZrO3 [7], cubic Li3NbO4 [2] and Li3TaO4 [2]
Chemistry of Materials, 2013
Stoichiometric lithium cobalt oxide LiCoO 2 is known to exhibit several structural phase transitions with x in Li x CoO 2 at ambient temperature (T); e.g., an initial rhombohedral (R3̅ m) phase transforms into a monoclinic (C2/m) phase at x ∼ 0.5. In contrast, lithium overstoichiometric (Li) 3b [Li δ Co 1−δ ] 3a O 2−δ with δ ≥ ∼0.02, where δ is the Li + ions at the 3a (Co) site, maintains the R3̅ m symmetry until x ∼ 0.5 in Li x (Li δ Co 1−δ)O 2−δ at ambient T, and this is the reason why such material has been widely used in commercial lithium ion batteries. We performed X-ray diffraction measurements in the T range between 100 and 300 K for the lithium overstoichiometric Li x (Li 0.02 Co 0.98)O 1.98 samples with x = 1, 0.56, and 0.51 to understand the factors that govern the structural changes in Li x (Li δ Co 1−δ)O 2−δ with δ ≥ 0. Both x = 0.56 and 0.51 samples exhibit a structural phase transition from the high-T R3̅ m phase to the low-T C2/m phase at 250 K (=T s1). Furthermore, these samples indicate another structural phase transition at 170 K (=T s2); although their crystal structures still have the C2/m symmetry, the degree of monoclinic distortion starts to decrease below T s2 , associated with a magnetic anomaly and a freezing of the Li + ions at the 3b site. Because the two structural phase transitions of T s1 (=330 K) and T s2 (=150 K) are also observed for the stoichiometric Li x CoO 2 compound with x ∼ 0.5, the C2/m phase in Li x (Li δ Co 1−δ)O 2−δ is found to appear in the limited x and T ranges. The characteristics and possible origin of T s1 and T s2 for both stoichiometric Li x CoO 2 and lithium overstoichiometric Li x (Li 0.02 Co 0.98)O 1.98 samples are discussed.
QTAIM studies of [Li(DMSO)n]+ and [Al(DMSO)n]3+
Nucleation and Atmospheric Aerosols, 2015
Geometry optimization of [Li(DMSO) n ] + and [Al(DMSO) n ] 3+ complexes with n = 1-6 in DMSO (dimethyl sulfoxide, (CH 3) 2 SO) solutions is performed using DFT treatment with B3LYP hybrid functional and cc-pVDZ basis sets. Solvent effects are approximated within Integral Equation Formalism Polarisable Continuum Model. Electron structure of individual model systems is investigated in terms of Quantum Theory of Atoms-in-Molecule topological analysis of electron density. Metal-DMSO bonding through oxygen atom is preferred. The most probable coordination numbers n = 4 for Li + and n = 6 for Al 3+ complexes with DMSO are concluded.
Inorganic Chemistry, 2004
A new ternary aluminide, LaNi 1+x Al 6-x (x = 0.44), has been synthesized from La, Ni, and Al in sealed silica tubes. Its structure, determined by single-crystal X-ray diffraction, is tetragonal P4/mmm (No. 123) with Z = 1 and has the lattice parameters a = 4.200(8) and c = 8.080(8) Å. Refinement based on F o 2 yielded R 1 = 0.0197 and wR 2 = 0.020 [I > 2σ(I)]. The compound adopts a structure type previously observed in SrAu 2 Ga 5 and EuAu 2 Ga 5. The atomic arrangement is closely related to the one in BaAl 4 as well as in other rare-earth gallide compounds such as LaNi 0.6 Ga 6 , HoCoGa 5 , Ce 4 Ni 2 Ga 20 , Ce 4 Ni 2 Ga 17 , Ce 4 NiGa 18 , and Ce 3 Ni 2 Ga 15. This structure exhibits a large open cavity which may be filled by a guest atom. Band structure calculations using density functional theory have been carried out to understand the stability of this new compound.