Monoclinic honeycomb-layered compound Li3Ni2SbO6: preparation, crystal structure and magnetic properties

Two synthetic routes-ion-exchange preparation from layered Na(3)Ni(2)SbO(6) at 300 °C and direct solid-state synthesis at 1150 °C resulted in layered Li(3)Ni(2)SbO(6), a cation-ordered derivative from the rocksalt type. The Fddd form reported earlier could not be reproduced. According to the XRD Rietveld analysis, Li(3)Ni(2)SbO(6) is a pseudohexagonal monoclinic structure, C2/m, with a = 5.1828(2) ?, b = 8.9677(3) ?, c = 5.1577(2) ?, β = 109.696(2)°. No Li/Ni mixed occupancy was detected. At high temperatures, the magnetic susceptibility follows the Curie-Weiss law with a positive value of Weiss temperature, ～8 K, indicating a predominance of ferromagnetic interactions. However, Li(3)Ni(2)SbO(6) orders antiferromagnetically at T(N)～ 15 K. The effective magnetic moment is 4.3 μ(B)/f.u. which satisfactorily agrees with theoretical estimations assuming high-spin configuration of Ni(2+) (S = 1). Electron spin resonance (ESR) spectra show single Lorentzian shape line attributed to Ni(2+) ion in octahedral coordination. The absorption is characterized by isotropic temperature independent effective g-factor g = 2.150 ± 0.005. In accordance with the layered honeycomb crystal structure determined for Li(3)Ni(2)SbO(6), the superexchange interaction between Ni(2+) ions through Ni-O-Ni pathways within Ni(2)SbO(6) layers are assumed to be ferromagnetic, while the dominant interaction between layers is antiferromagnetic.     

Double NASICON-type cell: ordered Nd3+ distribution in Li0.2Nd0.8/3Zr2(PO4)3

The NASICON compound Li(0.2)Nd(0.8/3)Zr(2)(PO(4))(3), synthesized by a sol-gel process, has been structurally characterized by TEM and powder diffraction (neutron and X-ray). It crystallizes in the space group R3[combining macron] (No. 148): at room temperature, the Nd(3+) ions present an ordered distribution in the [Zr(2)(PO(4))(3)](-) network which leads to a doubling of the classical c parameter (a = 8.7160(3) A, c = 46.105(1) A). Above 600 degrees C, Nd(3+) diffusion occurs leading at 1000 degrees C to the loss of the supercell. This reversible cationic diffusion in a preserved 3D [Zr(2)(PO(4))(3)](-) network is followed through thermal X-ray diffraction. Ionic conductivity measurements have been undertaken by impedance spectroscopy, while some results concerning the sintering of the NASICON compound are given.     

BiO(IO3): a new polar iodate that exhibits an aurivillius-type (Bi2O2)2+ layer and a large SHG response

A new noncentrosymmetric (NCS) and polar material containing two lone-pair cations, Bi(3+) and I(5+), and exhibiting an Aurivillius-type (Bi(2)O(2))(2+) layer has been synthesized and structurally characterized. The material, BiO(IO(3)), exhibits strong second-harmonic generation (SHG), ～12.5 × KDP (or ～500 × α-SiO(2)), using 1064 nm radiation, and is found in the NCS polar orthorhombic space group Pca2(1) (No. 29). The structure consists of (Bi(2)O(2))(2+) cationic layers that are connected to (IO(3))(-) anions. The macroscopic polarity, observed along the c-axis direction, may be attributed to the alignment of the IO(3) polyhedra. In addition to the crystal structure and SHG measurements, polarization and piezoelectric measurements were performed, as well as electronic structure analysis.     

A novel one-dimensional cyano-bridged Ni3Fe2 ferromagnet constructed from bimetallic molecular squares

Reaction of the complex [Ni(rac-CTH)](2+) (rac-CTH = rac-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) with [Fe(CN)(6)](3-) leads to a novel cyano-bridged Ni(3)Fe(2) complex, [[Ni(rac-CTH)](3)[Fe(CN)(6)](2)](4). The structure consists of an alternating arrangement of [Fe(CN)(6)Ni(rac-CTH)](2) squares and trans-planar [Ni(rac-CTH)](2+) units bridged by cyanide groups to give a neutral 1D chain running along the a axis. Magnetic measurements reveal the occurrence of ferromagnetic coupling between Fe(III) and Ni(II) ions and 3D magnetic ordering at 3 K due to interchain interactions. Canting of the moments is inferred from the low value of the magnetization of the saturation below T(c).     

Ca(2+)/vacancies and O2-/F- ordering in new oxyfluoride pyrochlores Li(2x)Ca1.5-x square 0.5-xM2O6F (M = Nb,Ta) for 0 < or = x < or = 0.5

New oxyfluorides Li(2x)Ca(1.5-x) square (0.5-x)M2O6F (M = Nb, Ta), belonging to the cubic pyrochlore structural type (Z = 8, a approximately 10.5 angstroms), were synthesized by solid state reaction for 0 < or = x < or = 0.5. XRD data allowed us to determine their structures from single crystals for the two alpha and beta-Ca(1.5) square (0.5)Nb2O6F forms and from powder samples for the others. This characterisation was completed by TEM and solid state 19F NMR experiments. For the Ca(1.5) square (0.5)M2O6F (x = 0) pyrochlore phases, the presence of a double ordering phenomenon is demonstrated, involving on one hand the Ca(2+) ions and the vacancies and on the other hand the oxide and the fluoride anions which are strictly located in the 8b sites of the Fd3m aristotype space group. The Ca(2+) ions/vacancies ordering leads to a reversible phase transition, a (P4(3)32) <--> beta (Fd3m). The 19F NMR study strongly suggests that, in the beta-phases, the fluoride ions are only on average at the centre of the Ca3 square tetrahedron. It shows that slightly different Ca-F distances occuring in alpha-Ca(1.5) square (0.5)Nb2O6F may be related to a more difficult thermal ionic and vacancies diffusion process than in the tantalate compound. This may explain the hysteresis phenomenon presented by the phase transition. A solid solution Li(2x)Ca(1.5-x) square (0.5-x) Ta2O6F (0 < or = x < or = 0.5) was prepared and the order-disorder phase transition observed for Ca(1.5) square (0.5)M2MO6F compounds disappears for all the other compositions where less or no more vacancies exist in the 16d sites. In the LiCaM2O6F compounds, the 19F NMR study allows us to determine the Ca(2+) and Li+ ions distributions around the fluoride ions and shows that the [FLi2Ca2] environment is clearly favoured.     

A three-dimensional ferromagnet, [Ni(dipn)]3[Cr(CN)6]2.3H2O (dipn = dipropylene triamine), based on a cubic Cr8Ni12 unit

The combination of Ni2+, dipropylenetriamine (dipn), and [Cr(CN)6]3- affords the cyanide-bridged bimetallic assembly, [Ni(dipn)]3[Cr(CN)6]2.3H2O (1). This compound crystallizes in cubic space group Pa, with a = b = c = 20.9742(7) A and Z = 8. A three-dimensional network is constructed on the basis of a Cr8Ni12 cubane unit formed by an alternate array of [Cr(CN)6]3- and [Ni(dipn)]2+ units through Cr-CN-Ni-NC-Cr edges. Cryomagnetic studies reveal a ferromagnetic interaction between Cr(III) and Ni(II) ions and a long-range ferromagnetic ordering below 42 K with very small coercive field. To the best of our knowledge, this compound is the first "complete ferromagnet" providing three-dimensional ferromagnetic interaction through a three-dimensional bridging structure that is based on a cubic unit among general metal-oxide and molecule-based magnets. Magnetooptical studies demonstrate a strong correlation between magnetic and optical properties.     

6/7Li NMR study of the Li1-zNi1+zO2 phases

A series of Li1-zNi1+zO2 materials have been synthesised by the coprecipitation route. An X-ray diffraction study was carried out on these materials using the Rietveld method to determine the departure from the ideal stoichiometry z, which ranges from 0 to 0.138. The actual Li/Ni ratio was also checked by chemical analyses using inductively coupled plasma (ICP) for each sample. The stoichiometric sample (z approximately 0) was obtained using a 15% Li excess. (6/7)Li NMR results from LiNiO2 (z approximately 0) show that the asymmetric shape of the NMR signal is due to anisotropy. Calculations give evidence that the paramagnetic dipolar interaction from the electron spins carried by Ni is anisotropic but does not completely explain the experimental anisotropy. (6)Li MAS NMR (magic angle spinning NMR) experiments and temperature standardisation NMR measurements unambiguously assign the isotropic position at +726 ppm. The static-echo NMR spectra of the non-stoichiometric Li1-zNi1+zO2 phases also exhibit an asymmetric shape whose width increases with the departure from the ideal stoichiometry z. (6/7)Li static and MAS NMR show that the 2zNi(2+) ions thus formed modify the dipolar interaction within the materials and also affect the Fermi contact interaction, since a distribution of Li environments is observed using (6)Li NMR for non-stoichiometric samples.     

Crystal growth of two new photoluminescent oxides: Sr3Li6Nb2O11 and Sr3Li6Ta2O11

Single crystals of Sr3Li6M2O11 (M = Nb, Ta) were grown out of a high-temperature Sr(OH)2/LiOH/KOH flux. The single crystal X-ray diffraction data were indexed to the orthorhombic Pmma system, with a = 10.5834(15) A, b = 8.3103(13) A, c = 5.8277(8) A, V = 512.55(13) A(3), and Z = 2 for Sr3Li6Nb2O11 and a = 10.5936(6) A, b = 8.3452(5) A, c = 5.8271(4) A, V = 515.15(6) A(3), and Z = 2 for Sr3Li6Ta2O11. The crystal structure consists of sheets of interconnected SrO8 polyhedra that are separated by M-O layers and an intervening LiO(x) polyhedral framework, representing a new structural type. The M-O layers exhibit a rare occurrence of both five- and six-coordinated M(5+) ions in the same structure. The oxides, upon excitation at 250 nm, exhibit violet emission at room temperature.     

Exploring the emissive properties of new azacrown compounds bearing aryl, furyl, or thienyl moieties: a special case of chelation enhancement of fluorescence upon interaction with Ca(2+), Cu(2+), or Ni(2+)

Three new compounds bearing furyl, aryl, or thienyl moieties linked to an imidazo-crown ether system (1, 2, and 3) were synthesized and fully characterized by elemental analysis, infrared, UV-vis absorption, and emission spectroscopy, X-ray crystal diffraction, and MALDI-TOF-MS spectrometry. The interaction toward metal ions (Ca(2+), Cu(2+), Ni(2+), and Hg(2+)) and F(-) has been explored in solution by absorption and fluorescence spectroscopy. Mononuclear and binuclear metal complexes using Cu(2+) or Hg(2+) as metal centers have been synthesized and characterized. Compounds 2 and 3 show a noticeable enhancement of the fluorescence intensity in the presence of Ca(2+) and Cu(2+) ions. Moreover compound 3 presents a dual sensory detection way by modification of the fluorimetric and colorimetric properties in the presence of Cu(2+) or Hg(2+). EPR studies in frozen solution and in microcrystalline state of the dinuclear Cu(II)3 complex revealed the presence of an unique Cu(2+) type.     

Comparison of the structure and magnetic order in a series of layered Ni(II) organophosphonates, Ni[(RPO3)(H2O)] (R = C6H5, CH3, C18H37)

The reaction of nickel chloride with phenyl phosphonic acid under hydrothermal conditions resulted in the isolation of yellow-green single crystals of Ni[(C(6)H(5)PO(3))(H(2)O)]. The structure of the compound has been solved by X-ray single-crystal diffraction studies. Ni[(C(6)H(5)PO(3))(H(2)O)] crystallizes in the orthorhombic space group Pmn2(1) and is isostructural with the Mn(II), Fe(II), and Co(II) analogues. It presents the typical features of the hybrid 2D structures, consisting of alternating inorganic and organic layers. The former are formed by six-coordinated nickel(II) ions bridged by oxygen atoms into the layers. The inorganic layers are capped by the phenyl phosphonate groups, with phenyl groups of two adjacent ligands forming a hydrophobic bilayer region, and van der Waals contacts are established between them. The magnetic properties investigated by means of dc and ac susceptibility measurements point to an AF exchange coupling between nearest neighboring Ni(II) ions. Below 5 K, the compound orders magnetically showing the typical features of a canted antiferromagnet. The magnetic behavior and magnetic dimensionality of Ni[(C(6)H(5)PO(3))(H(2)O)] have been fully analyzed and compared to those of the Ni(II) parent compounds Ni[(RPO(3))(H(2)O)] (where R = CH(3), C(18)H(37)), which exhibit different symmetries of the inorganic layers and lengths of the R groups.     

Synthesis, Structure, and Characterization of New Li(+) - d(0) -Lone-Pair - Oxides: Noncentrosymmetric Polar Li(6)(Mo(2)O(5))(3)(SeO(3))(6) and Centrosymmetric Li(2)(MO(3))(TeO(3)) (M = Mo(6+) or W(6+))

New quaternary lithium - d(0) cation - lone-pair oxides, Li(6)(Mo(2)O(5))(3)(SeO(3))(6) (Pmn2(1)) and Li(2)(MO(3))(TeO(3)) (P2(1)/n) (M = Mo(6+) or W(6+)), have been synthesized and characterized. The former is noncentrosymmetric and polar, whereas the latter is centrosymmetric. Their crystal structures exhibit zigzag anionic layers composed of distorted MO(6) and asymmetric AO(3) (A = Se(4+) or Te(4+)) polyhedra. The anionic layers stack along a 2-fold screw axis and are separated by Li(+) cations. Powder SHG measurements on Li(6)(Mo(2)O(5))(3)(SeO(3))(6) using 1064 nm radiation reveal a SHG efficiency of approximately 170 × α-SiO(2). Particle size vs SHG efficiency measurements indicate Li(6)(Mo(2)O(5))(3)(SeO(3))(6) is type 1 nonphase-matchable. Converse piezoelectric measurements result in a d(33) value of ～28 pm/V and pyroelectric measurements reveal a pyroelectric coefficient of -0.43 μC/m(2)K at 50 °C for Li(6)(Mo(2)O(5))(3)(SeO(3))(6). Frequency-dependent polarization measurements confirm that Li(6)(Mo(2)O(5))(3)(SeO(3))(6) is nonferroelectric, i.e., the macroscopic polarization is not reversible, or 'switchable'. Infrared, UV-vis, thermogravimetric, and differential thermal analysis measurements and electron localization function calculations were also done for all materials.     

Closely related rare-earth metal germanides RE2Li2Ge3 and RE3Li4Ge4 (RE = La-Nd, Sm): synthesis, crystal chemistry, and magnetic properties

Reported are the syntheses, crystal structures, and magnetic susceptibilities of two series of closely related rare-earth metal-lithium germanides RE(2)Li(2)Ge(3) and RE(3)Li(4)Ge(4) (RE = La-Nd, Sm). All title compounds have been synthesized by reactions of the corresponding elements at high temperatures, and their structures have been established by single-crystal X-ray diffraction. RE(2)Li(2)Ge(3) phases crystallize in the orthorhombic space group Cmcm (No. 63) with the Ce(2)Li(2)Ge(3) structure type, while the RE(3)Li(4)Ge(4) phases crystallize in the orthorhombic space group Immm (No. 71) with the Zr(3)Cu(4)Si(4) structure type, respectively. Both of their structures can be recognized as the intergrowths of MgAl(2)Cu- and AlB(2)-like slabs, and these traits of the crystal chemistry are discussed. Temperature-dependent direct-current magnetization measurements indicate Curie-Weiss paramagnetism in the high-temperature regime for RE(2)Li(2)Ge(3) and RE(3)Li(4)Ge(4) (RE = Ce, Pr, Nd), while Sm(2)Li(2)Ge(3) and Sm(3)Li(4)Ge(4) exhibit Van Vleck-type paramagnetism. The data are consistent with the local-moment magnetism expected for RE(3+) ground states. At temperatures below ca. 20 K, magnetic ordering transitions have been observed. The experimental results have been complemented by tight-binding linear muffin-tin orbital electronic-band-structure calculations.     

Coupled ion/electron hopping in Li(x)NiO2: a 7Li NMR study

Deintercalated "Li(x)NiO2" materials (x = 0.25, 0.33, 0.50, 0.58, and 0.65) were obtained using the electrochemical route from the Li0.985Ni1.015O2 and Li0.993Ni1.007O2 compounds. Refinements of X-ray diffraction data using the Rietveld method show a good agreement with the phase diagram of the Li(x)NiO2 system studied earlier in this laboratory. Electronic conductivity measurements show a thermally activated electron-hopping process for the deintercalated Li0.5NiO2 phase. In the Li(x)NiO2 materials investigated (x = 0.25, 0.33, 0.50, and 0.58), 7Li NMR shows mobility effects leading to an exchanged signal at room temperature. A clear tendency for Li to be surrounded mainly by Ni3+ ions with the 180 degree configuration is observed, particularly, for strongly deintercalated materials with smaller Li+ and Ni3+ contents, even upon heating, when this mobility becomes very fast in the NMR time scale. This suggests that Li/vacancy hopping does occur on the NMR time scale but that Ni3+/Ni4+ hopping does not occur independently. The position of Li seems to govern the oxidation state of the Ni around it at any time; the electrons follow the Li ions to satisfy local electroneutrality and minimal energy configuration. The observed NMR shifts are compatible with the Li/vacancy and Ni3+/Ni4+ ordering patterns calculated by Arroyo y de Dompablo et al. for x = 0.25 and x = 0.50, but not for x = 0.33 and x = 0.58.     

Investigation of the charge compensation mechanism on the electrochemically Li-ion deintercalated Li1-xCo1/3Ni1/3Mn1/3O2 electrode system by combination of soft and hard X-ray absorption spectroscopy

In situ hard X-ray absorption spectroscopy (XAS) at metal K-edges and soft XAS at O K-edge and metal L-edges have been carried out during the first charging process for the layered Li1-xCo1/3Ni1/3Mn1/3O2 cathode material. The metal K-edge XANES results show that the major charge compensation at the metal site during Li-ion deintercalation is achieved by the oxidation of Ni2+ ions, while the manganese ions and the cobalt ions remain mostly unchanged in the Mn4+ and Co3+ state. These conclusions are in good agreement with the results of the metal K-edge EXAFS data. Metal L-edge XAS results at different charge states in both the FY and PEY modes show that, unlike Mn and Co ions, Ni ions at the surface are oxidized to Ni3+ during charge, whereas Ni ions in the bulk are further oxidized to Ni4+ during charge. From the observation of O K-edge XAS results, we can conclude that a large portion of the charge compensation during Li-ion deintercalation is achieved in the oxygen site. By comparison to our earlier results on the Li1-xNi0.5Mn0.5O2 system, we attribute the active participation of oxygen in the redox process in Li1-xCo1/3Ni1/3Mn1/3O2 to be related to the presence of Co in this system.     

NMR study of Li+ ion dynamics in the perovskite Li(3x)La(1/3-x)NbO3

(7)Li and (6)Li nuclear magnetic resonance (NMR) experiments are carried out on the perovskite Li(3x)La(1/3-x)NbO(3). The results are compared to those obtained on the titanate Li(3x)La(2/3-x)TiO3 (LLTO) in order to investigate the effect, on the lithium ion dynamics, of the total substitution of Nb(5+) for Ti(4+) in the B-site of the ABO(3) perovskites. The XRD patterns analysis reveals that this substitution leads to a change in the distribution of the La(3+) ions in the structure. La(3+) ions distribution is very important, in regard to ionic conductivity, because these immobile ions can be considered as obstacles for the long-range Li+ motion. If compared to the titanates, the compounds of the niobate solid solution have a bigger unit cell volume, a smaller number of La(3+) ions, and a higher number of vacancies. These should favor the motion of the mobile ions into the structure. This is not experimentally observed. Therefore, the interactions between the mobile species and their environment greatly influence their mobility. (7)Li and (6)Li NMR relaxation time experiments reveal that the Li relaxation mechanism is not dominated by quadrupolar interaction. (7)Li NMR spectra reveal the presence of different Li+ ion sites. Some Li+ ions reside in an isotropic environment with no distortion, some others reside in weakly distorted environments. T(1), T(1)(rho), and T(2) experiments allow us to evidence two motions of Li+. As in LLTO, T(1) probes a fast motion of the Li+ ions inside the A-cage of the perovskite structure and T(1)(rho) a slow motion of these ions from A-cage to A-cage. At variance with what has been observed in LLTO, these different Li+ ions can be differentiated through the spin-lattice relaxation times, T(1) and T(1)(rho), as well as through the transverse relaxation time, T(2).     

Ge(7)O(13)(OH)(2)F(3)](3)(-).Cl(-).2[Ni(dien)(2)](2+): the first chainlike germanate templated by a transition metal complex

The first chainlike germanate, [Ge(7)O(13)(OH)(2)F(3)](3)(-).Cl(-).2[Ni(dien)(2)](2+), has been solvothermally synthesized by using Ni(dien)(2)(2+) cations as the template and characterized by IR, SEM, TGA, powder X-ray diffraction (PXRD), energy-dispersive X-ray analysis (EDXA), elemental analysis, and single-crystal X-ray diffraction, respectively. This compound crystallized in the monoclinic space group P2/nwith a = 8.8904(2) A, b = 17.4374(3) A, c = 13.2110(3) A, beta = 101.352(1) degrees, V = 2007.97(7) A(3), and Z = 2. Interestingly, the structure contains two types of chiral mer-[Ni(dien)(2)](2+) cations and two types of chiral chains, one left-handed and the other right-handed, which lead to a racemic compound. The orderly separation of achiral s-fac-[Ni(dien)(2)](2+) and chiral mer-[Ni(dien)(2)](2+) isomers was found in the structure. The structure is stabilized by N-H.O(F, Cl) hydrogen bonds.     

Li(+) ion conductivity in rock salt-structured nickel-doped Li(3)NbO(4)

Two mechanisms of doping Li(3)NbO(4), which has an ordered, rock salt superstructure, have been established. In the "stoichiometric mechanism", the overall cation-to-anion ratio is maintained at 1:1 by means of the substitution 3Li(+) + Nb(5+) --> 4Ni(2+). In the "vacancy mechanism", Li(+) ion vacancies are created by means of the substitution 2Li(+) --> Ni(2+). Solid solution ranges have been determined for both mechanisms and a partial phase diagram constructed for the stoichiometric join. On the vacancy join, the substitution mechanism has been confirmed by powder neutron diffraction; associated with lithium vacancy creation, a dramatic increase in Li(+) ion conductivity occurs with increasing Ni content, reaching a value of 5 x 10(-4) Omega(-1) cm(-1) at 300 degrees C for composition x= 0.1 in the formula Li(3-2x)Ni(x)NbO(4). This is the first example of high Li(+) ion conductivity in complex oxides with rock salt-related structures.     

Development of a force field for Li(2)SiF(6)

A force field has been developed for Li(2)SiF(6) for subsequent use in Molecular Dynamics (MD) simulations involving Li(+) and SiF(2-) (6) ions in a polymer electrolyte host. Both ab initio calculations and available empirical data have been used. The force field has been verified in simulations of the crystal structure of Li(2)SiF(6) in two different space groups: P321 and P3(-)m1. The use of MD simulation to assess the correct space group for Li(2)SiF(6) shows that it is probably P321.     

Synthesis, crystal chemistry, and magnetic properties of RE7Li8Ge10 and RE11Li12Ge16 (RE = La-Nd, Sm): new members of the [REGe2](n)[RELi2Ge](m) homologous series

Eight new rare-earth metal-lithium-germanides belonging to the [REGe(2)](n)[RELi(2)Ge](m) homologous series have been synthesized and structurally characterized by single-crystal X-ray diffraction. The structures of the title compounds can be rationalized as linear intergrowths of imaginary RELi(2)Ge (MgAl(2)Cu structure type) and REGe(2) (AlB(2) structure type) slabs. The compounds with general formula RE(7)Li(8)Ge(10) (RE = La-Nd, Sm), i.e., [REGe(2)](3)[RELi(2)Ge](4), crystallize in the orthorhombic space group Cmmm (No. 65) with a new structure type. Similarly, the compounds with general formula RE(11)Li(12)Ge(16) (RE = Ce-Nd), i.e., [REGe(2)](5)[RELi(2)Ge](6), crystallize in the orthorhombic space group Immm (No. 71) also with its own structure type. Temperature-dependent DC magnetization measurements indicate Curie-Weiss paramagnetism in the high-temperature regime and hint at complex magnetic ordering at low temperatures. The measured effective moments are consistent with RE(3+) ground states in all cases. The experimental results have been complemented by tight-binding linear muffin-tin orbital (TB-LMTO) electronic structure calculations.     

On the high magnetic-ordering temperature of the 5d magnetic oxide Ca3LiOsO6 crystallizing in a trigonal crystal structure: density functional analysis

The 5d magnetic oxide Ca(3)LiOsO(6) has a trigonal arrangement of its LiOsO(6) chains parallel to the c-direction and hence has triangular arrangements of high-spin Os(5+) (d(3)) ions but exhibits no spin frustration and undergoes a long-range antiferromagnetic ordering at a high temperature. The origin of this apparently puzzling observation was examined by evaluating the nearest-neighbor Os-O···O-Os spin exchange interactions of Ca(3)LiOsO(6) on the basis of density functional calculations. Our study shows that, of the two nearest-neighbor interchain spin exchanges, one dominates over the other and that the intrachain spin exchange and the dominating interchain spin exchange are strong and form a three-dimensional antiferromagnetic spin lattice with no spin frustration, which is responsible for the long-range antiferromagnetic ordering of Ca(3)LiOsO(6) at high temperature. In determining the strengths of the Os-O···O-Os exchange interactions of Ca(3)LiOsO(6), the Li(+) and Ca(2+) ions of the O···Li(+)···O and O···Ca(2+)···O linkages are found to play only a minor role.