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By tackling the challenge of extending transparent oxide semiconductors to Ge based oxides, we have found a not-yet-reported crystal structure, named $\beta$-SrGe$_2$O$_5$, which is composed of edge-sharing GeO$_6$ octahedra interconnected by GeO$_5$ bipyramids. Single crystals were successfully grown by the high-pressure flux method. $\beta$-SrGe$_2$O$_5$ has a band gap of 5.2 eV and a dispersive conduction band with an effective mass as small as 0.34 times the electron rest mass, which originates from the edge-sharing GeO$_6$ octahedra network. Although known compounds with octahedral GeO$_6$ coordination are commonly unstable at atmospheric pressure and elevated temperatures, $\beta$-SrGe$_2$O$_5$ exhibits thermal stability up to 700 $^\circ$C., Comment: 23 pages, 8 figures

We synthesized the 5d1-transition metal oxides AOsO4 (A = K, Rb, Cs) by solid-state reaction, and performed structure determination and magnetic and heat capacity measurements. It was found that they crystallize in a scheelite (A = K and Rb) or a quasi-scheelite structure (A = Cs) comprising of distorted diamond lattices of septivalent Os (d1) ions tetrahedrally coordinated by four oxide ions without local inversion symmetry; hence an antisymmetric spin-orbit coupling is expected in the crystals. The K and Rb compounds have Weiss temperatures of theta = -66 and -18 K, effective magnetic moments of mu_eff = 1.44 and 1.45 mu_B/Os, and antiferromagnetic transition temperatures of T_N = 36.9 and 21.0 K, respectively. In contrast, the Cs compound has theta = 12 K and mu_eff = 0.8 mu_B/Os without magnetic transition above 2 K, instead exhibiting a first-order structural transition at T_s = 152.5 K. The decline of the Os moment from 1.73 mu_B/Os for the simple d1 spin, particularly for Cs, is likely to originate from the antiparallel orbital moment, although the spin-orbit coupling is generally quenched in the low-lying e orbitals.

The effects of aluminum substitution on the structure and electric properties of langasite (La3Ga5SiO14) family crystals are reported. The maximum Al content x of La3Ga5-xAlxSiO14 (LGAS), La3Nb0.5Ga5.5-xAlxO14 (LNGA), and La3Ta0.5Ga5.5-xAlxO14 (LTGA) crystals grown by the conventional Czochralski technique are x = 0.9, 0.2, and 0.5, respectively. Single-crystal X-ray structural analysis reveals that Al atoms are distributed in all cation sites except for the decahedral one occupied by La, rather than favoring the smallest tetrahedral sites. The electrical properties of the Al-substituted crystals were also compared with those of pure ones. Al substitution was found to affect the piezoelectric constant d14, but not d11. The LGAS and LTGA crystals exhibit higher electric resistivity ρ as a result of Al substitution. Among the Al-substituted and pure crystals, the LTGA crystal featured the lowest temperature dependence of d11 and highest ρ, making it the most suitable of the group for high-temperature piezoelectric applications.

To investigate chiral properties, it is important to prepare the enantiopure crystals. We grow a large enantiopure crystal of inorganic chiral magnet YbNi3Al9 via the flux method with a temperature...

The structural properties of the iron mixed-valence complex ( n-C3H7)4N[FeIIFeIII(dto)3] (dto = dithiooxalato, C2O2S2) have been investigated by single-crystal X-ray diffraction (SCXRD) at low temperatures. ( n-C3H7)4N[FeIIFeIII(dto)3] has two-dimensional (2D) honeycomb layers consisting of alternating FeII and FeIII arrays bonded by bis-bidentate dithiooxalato ligands. Upon cooling, a superlattice structure with q = (1/3, 1/3, 0) was observed below 260 K, which corresponds to an order-disorder transition of the ( n-C3H7)4N+ ions between the honeycomb layers. The charge-transfer phase transition (CTPT) occurs at TC↑1/2 ∼ 120 K and TC↓1/2 ∼ 90 K upon heating and cooling, respectively, with an electron transfer between the FeII and FeIII ions, accompanied by a spin-state change, FeII ( S = 2; HS)-O2C2S2-FeIII ( S = 1/2; LS) ↔ FeIII ( S = 5/2; HS)-O2C2S2-FeII ( S = 0; LS). During the CTPT, the intersheet [FeIIFeIII(dto)3] distance decreased monotonously upon cooling, and an abrupt structural contraction was observed in the hexagonal 2D network. The volume contraction during the CTPT was quite small (∼0.7%), and differences in the structural distortions at the FeS6 and FeO6 sites were not found in the vicinity of the CTPT. We also calculated the orbital energies and the occupied spin states for the [Fe(O2C2S2)3] and [Fe(S2C2O2)3] octahedra in the vicinity of the CTPT by density functional theory (DFT). Because the local symmetry around the two coordinating iron ions is already lowered to trigonal symmetry, the CTPT did not cause any further deformation. This symmetry invariance resulted in an absence of orbital contributions to the total entropy change (Δ S) in the CTPT, which is in agreement with the previous heat capacity measurements. [Nakamoto, T; Miyazaki, Y; Itoi, M; Ono, Y; Kojima, N; Sorai, M. Heat Capacity of the Mixed-Valence Complex {[( n-C3H7)4N][FeIIFeIII(dto)3]}∞, Phase Transition because of Electron Transfer, and a Change in Spin-State of the Whole System. Angew. Chem., Int. Ed. 2001, 40, 4716-4719.].

This paper focuses on effects of isovalent La substitution on the crystal structure and dielectric properties of ferroelectric $\mathrm{B}{\mathrm{i}}_{2}\mathrm{Si}{\mathrm{O}}_{5}$. Polycrystalline samples of ${(\mathrm{B}{\mathrm{i}}_{1\ensuremath{-}x}\mathrm{L}{\mathrm{a}}_{x})}_{2}\mathrm{Si}{\mathrm{O}}_{5}$ are synthesized by crystallization of Bi-Si-O and Bi-La-Si-O glasses with a composition range of $0\ensuremath{\le}x\ensuremath{\le}0.1$. The crystal structure changes from monoclinic to tetragonal with increasing La-substitution rate $x$ at room temperature. This structural variation stems from the change in orientation of $\mathrm{Si}{\mathrm{O}}_{4}$ tetrahedra that form one-dimensional chains when they are in the ordered configuration, thus suggesting that lone-pair electrons play an important role in sustaining one-dimensional chains of $\mathrm{Si}{\mathrm{O}}_{4}$ tetrahedra. Synchronizing with the disordering of $\mathrm{Si}{\mathrm{O}}_{4}$ chains, ferroelectric phase transition temperature of ${(\mathrm{B}{\mathrm{i}}_{1\ensuremath{-}x}\mathrm{L}{\mathrm{a}}_{x})}_{2}\mathrm{Si}{\mathrm{O}}_{5}$ sharply decreases as $x$ increases, and ferroelectricity finally vanishes at around $x=0.03$. The present results demonstrate that lone-pair electrons of Bi play an important role in the ferroelectricity of $\mathrm{B}{\mathrm{i}}_{2}\mathrm{Si}{\mathrm{O}}_{5}$ through propping the ordered structure of one-dimensional $\mathrm{Si}{\mathrm{O}}_{4}$ chains with stereochemical activity. Furthermore, an additional phase transition has been first discovered in the low-temperature region of ${(\mathrm{B}{\mathrm{i}}_{1\ensuremath{-}x}\mathrm{L}{\mathrm{a}}_{x})}_{2}\mathrm{Si}{\mathrm{O}}_{5}$ with $x\ensuremath{\le}0.01$, where the ordered one-dimensional $\mathrm{Si}{\mathrm{O}}_{4}$ chains remain.

A novel charge-disproportionation state with δ = 0.75 was observed in an electron-donor (D)/-acceptor (A) D(δ+)2A(2δ-) layered framework by chemically tuning the electron-donating affinity of D at the boundary between D(0.5+)2A(-) and D(+)2A(2-) phases, which was pressure-sensitive due to the formation of the D(+)2A(2-) oxidation state.

A conducting molecular crystal TPP[MnIII(Pc)(CN)2]2 (MnIII: d4, S = 1, TPP = tetraphenylphosphonium and Pc = phthalocyanine) was fabricated. In its crystal structure, the [MnIII(Pc)(CN)2] units formed a one-dimensional regular chain along the c-axis with an overlap integral value of 8.6 × 10-3. TPP[MnIII(Pc)(CN)2]2 showed a semiconducting behaviour that also has been observed for isostructural TPP[CoIII(Pc)(CN)2]2 (CoIII: d6, S = 0) and TPP[FeIII(Pc)(CN)2]2 (FeIII: d5, S = 1/2) whose ground states are charge-ordered states. In spite of the local magnetic moment of the MnIII ion (S = 1) at the centre of the Pc ligand, TPP[MnIII(Pc)(CN)2]2 exhibited an almost isotropic and small negative magnetoresistance (MR) effect (the MR ratio was -8.7% under 8 T at 10.7 K), contrarily to the anisotropic giant negative MR effect of TPP[FeIII(Pc)(CN)2]2. The isotropy was found to be due to a (dxz)1(dyz)1 electronic configuration, and the smaller MR effect was explained by a weaker antiferromagnetic interaction between MnIII ions than that between FeIII ions, as suggested by a Weiss temperature Θ of -3.1 K (|Jdd|/kB = 1.2 K).

Compositionally tunable vanadium oxyhydrides Sr2VO4-xHx (x = 0 - 1) without considerable anion vacancy were synthesized by high-pressure solid state reaction. The crystal structures and their properties were characterized by powder neutron diffraction, synchrotron X-ray diffraction, thermal desorption spectroscopy, and first-principles density functional theory (DFT) calculations. The hydrogen anions selectively replaced equatorial oxygen sites in the VO6 layers via statistical substitution of hydrogen in the low x region (x < 0.2). A new orthorhombic phase (Immm) with an almost entirely hydrogen-ordered structure formed from the K2NiF4-type tetragonal phase with x > 0.7. Based on the DFT calculations, the degree of oxygen/hydrogen anion ordering is strongly correlated with the bonding interaction between vanadium and the ligands., 19 pages, 5 figures

The first Cr-dominant amphibole, ehimeite, ideally NaCa2Mg4CrSi6Al2O22(OH)2, has been found in a chromitite deposit in the Akaishi Mine, Higashi-Akaishi Mountain, Ehime Prefecture, Japan. Ehimeite occurs as prismatic crystals of up to 1.5 cm in length and 0.5 cm in width and is found in association with chromite, kammererite (Cr-rich clinochlore), Cr-poor clinochlore, phlogopite, and uvarovite. It is transparent, emerald green to pale green in color with pale green streaks, and has a vitreous luster. Optically, it is biaxial positive with α = 1.644(2), β = 1.647(2), γ = 1.659(2), and 2Vcalc. = 53°. It has a Mohs’ hardness of 6 and densities of 3.08(3) g/cm3 (measured using heavy liquids) and 3.121 g/cm3 (calculated from powder diffraction data and the empirical formula). The empirical formula is (Na0.88K0.07)Σ0.95(Ca1.89Na0.02Mg0.09)Σ2.00(Mg4.03Cr0.62Al0.19Fe3+0.07Fe2+0.07Ti0.03)Σ5.00(Si6.14Al1.86)Σ8.00O22(OH)2 on the basis of O = 22 and OH = 2, and ehimeite mainly forms a solid solution, NaCa2Mg4(Cr, Al)Si6Al2O22(OH)2, with pargasite. It has a monoclinic unit cell with a = 9.9176(14) A, b = 18.0009(12) A, c = 5.2850(7) A, β = 105.400(7)°, V = 909.6 (17) A3, and Z = 2, and it belongs to the space group C2/m, as refined from powder XRD data. The eight strongest lines in the powder XRD pattern [d (A), I/I0, hkl] are (3.370, 58, 150), (2.932, 43, 221), (2.697, 81, 151), (2.585, 50, 061), (2.546, 100, 202), (2.346, 42, 351), (2.156, 35, 261), and (1.514, 55, 263). The crystal structure has been refined to R1 = 0.0488 using single-crystal XRD data. It has been concluded that ehimeite in the Akaishi Mine was formed by the reaction of chromitite and the metamorphic fluid in the retrograde stage of serpentinization during the Sanbagawa metamorphism.

The effects of off-stoichiometry and elemental substitution on electronic properties of iron-based ladder compound ${\mathrm{BaFe}}_{2}{\mathrm{S}}_{3}$ are investigated. Resistivity and magnetization are revealed to be quite sensitive to the stoichiometry of Fe atoms, and 10% deficiency at Fe sites reduces the antiferromagnetic transition temperature by 40 K. The antiferromagnetic transition temperature decreases even faster and collapses to zero with hole doping through 10% K substitution at the Ba site, while the antiferromagnetic ordering phase remains with electron doping through 20% Co substitution at the Fe site. Such electron-hole asymmetry is opposite to two-dimensional iron-based superconductors, and can be explained on the basis of both itinerant and localized electronic pictures.

We report the structure and electric properties of La 3 Ta 0.5 Ga 5.5-x Al x O 14 (LTGAx,x = 0.0 (LTG), 0.3 and 0.5) single crystals, with a Ca 3 Ga 2 Ge 4 O 14 -type structure, suitable for high temperature piezoelectric application. A single-crystal X-ray structure analysis reveals that Al atoms are distributed in all cation sites except for the decahedral site occupied by La, which favors instead the octahedral site. The piezoelectric moduli d 11 kept a constant, whereas [d 14 ] increased 14% with the increasing Al content, x, up to 0.5. The LTGA0.5 crystals showed a low temperature dependence (2% deviation from room temperature to 400°C) of d 11 and a higher electric resistivity p than those of the LTG crystals. The Al substitution is effective for improving the electrical properties of the LTG.

The crystal structure of the β -pyrochlore oxide superconductor KOs2O6 is re-examined. A single-crystal X-ray diffraction (XRD) analysis at room temperature first revealed that the compound crystallizes in a cubic structure with the centrosymmetric space group F d 3 m , as in conventional pyrochlore oxides. Later, however, Schuck et al. claimed a different non-centrosymmetric F 4 3 m structure based on their single-crystal XRD analysis. To unambiguously determine the true crystal structure of KOs2O6, we carried out high-resolution synchrotron powder X-ray and convergent-beam electron diffraction measurements at room temperature. The space group was determined with high reliability to be centrosymmetric F d 3 m , not F 4 3 m . This confirms the importance of the K atom location in a high-symmetry site, which causes unusually large rattling of the K atom.

New copper complexes with Dmt-Pyra-STF (=dimethylthio-pyrazino-selenathiafulvalene) as the ligand—trans-[CuIICl2(Dmt-Pyra-STF)2] (1) and [CuI2Br2.5(Dmt-Pyra-STF)] (2)—have been synthesized by a vertical diffusion method. In complex 1, the donors form uniform stacking columns along the c axis to have a θ-type donor arrangement, but 1 is an insulator due to the absence of carriers. The magnetic susceptibility of 1 can be fitted to the Curie–Weiss rule (θ = −9.02 K) and suggests that the oxidation state of Cu ions in 1 is 2+. In contrast, complex 2 has supramolecular chains along the c axis, which are formed by CuI and Br−. In addition, this complex is a semiconductor with σrt = 0.16 S cm−1 and Ea = 0.10 eV. The magnetic susceptibility of 2 suggests that the oxidation state of Cu ions in 2 is 1+, namely [CuI2Br2.5(Dmt-Pyra-STF)0.5+]. Both complexes 1 and 2 demonstrate that pyrazino-fused STF derivatives can be coordinated to a copper even though the atomic orbital of Se is so large. Furthermore, we can firstly synthesize complex 2, in which both charge transfer and coordination occur simultaneously.

FeVO4 (I) single crystals are grown by the flux method using V2O5 as the self-flux. The grown crystals exhibit a characteristic morphology with natural facets. The quality of the crystals is confirmed by X-ray diffraction and EPMA techniques. Magnetic properties are investigated by means of magnetic susceptibility, magnetization, and heat capacity measurements. Two magnetic phase transitions are observed at ∼13 and ∼20 K. Such unusual magnetic behaviors are suggested to originate from two different Fe ligand environments of octahedral FeO6 and trigonal bipyramidal FeO5 in a six-column doubly bent chain.

New supramolecular copper complexes with pyrazinotetrathiafulvalene (pyra-TTF) as the ligand, [CuIICl2(pyra-TTF)] (1) and (pyra-TTF)2[CuI3Cl4(pyra-TTF)] (2), have been synthesized by the diffusion method. Complex 1 is a black block crystal with a three-dimensional (3-D) supramolecular network; the linear chain [−CuIICl2−(pyra-TTF)−]n extends along the b axis, where the coordinated pyra-TTF donors are stacked in a head-to-tail and ring-over-bond configuration to construct two-dimensional (2-D) sheets, and between the sheets, there are C···Cl− or H···Cl− contacts. Even though the electron spin resonance (ESR) measurement reveals the nearly CuII state, complex 1 is a semiconductor with σRT = 1.0 × 10−4 S cm−1 and Ea = 0.33 eV. The high-frequency conductivity measurement also confirmed the intrinsic slight carrier doping from CuII to the pyra-TTF donor. This slight doping enhances not only the real and imaginary dielectric constants but also the antiferromagnetic interaction between CuII spins following the 2...

Six materials, (EDT-TTF)(4)BrI(2)(TIE)(5) (1, where EDT-TTF = ethylenedithiotetrathiafulvalene and TIE = tetraiodoethylene), (EDST)(4)I(3)(TIE)(5) (2, where EDST = ethylenedithiodiselenadithiafulvalene), (MDT-TTF)(4)BrI(2)(TIE)(5) (3, where MDT-TTF = methylenedithiotetrathiafulvalene), (HMTSF)(2)Cl(2)(TIE)(3) (4, where HMTSF = hexamethylenetetraselenafulvalene), (PT)(2)Cl(DFBIB)(2) (5, where PT = bis(propylenedithio)tetrathiafulvalene and DFBIB = 1,4-difluoro-2,5-bis(iodoethynyl)benzene), and (TSF)Cl(HFTIEB) (6, where TSF = tetraselenafulvalene and HFTIEB = 1,1',3,3',5,5'-hexafluoro-2,2',4,4'-tris(iodoethynyl)-biphenyl), consisting of conducting nanowires were obtained by galvanostatic oxidation of the donor molecules in the presence of the corresponding halide anions and iodine-containing neutral molecules. We report their characterizations using single-crystal crystallography, electrical resistance measurements, and electron spin resonance. The structures are built on stacks of planar cations of the donors that are isolated electrically by an insulating network consisting of supramolecular assemblies of the halide anions and neutral molecules held together by a halogen bond. The size and shape as well as the orientation (tilt) of the donors are matched by the self-organization of the insulating sheaths in all cases, providing a pea-in-a-pod example in the field of supramolecular chemistry. The observed resistivities, resistivity anisotropies, and electron spin resonance behaviors of these salts are analyzed by tight-binding band calculations and resistance-array modeling. Crystal 6 with insulating layer of 1 nm thickness exhibits 8 orders of magnitude anisotropy in its resistivity, indicating high potential of the supramolecular network as sheathing material. The observation of such networks leads us to propose a roadmap for future development toward multidimensional memory devices.

We report 51V NMR experiments in the metallic phase of the quasi-one-dimensional (1D) conductor β - Sr 0.33 V 2 O 5 . The Knight shift and the quadrupole splitting of all six vanadium sites were determined as a function of the direction of magnetic field perpendicular to the conducting b -axis. Magnetic properties of the three 1D structural units are remarkably heterogeneous. In particular, the V2 ladder unit shows pronounced charge disproportionation among the two (V2a and V2b) sites. At one of these sites, the absolute value of the Knight shift and 1 / ( T 1 T ) increase steeply with decreasing temperature, suggesting development of ferromagnetic correlation.

Substitution of an oxygen anion with a hydrogen anion induced the low dimensionalization of magnetic ordering in a transition metal oxide $\mathrm{S}{\mathrm{r}}_{2}\mathrm{V}{\mathrm{O}}_{4}$. Upon increasing $x$ up to $\ensuremath{\sim}1$ in $\mathrm{S}{\mathrm{r}}_{2}\mathrm{V}{\mathrm{O}}_{4\ensuremath{-}x}{\mathrm{H}}_{x}$, the hydride ions were ordered linearly, and the magnetic susceptibility was simultaneously suppressed. It was found that this suppression was attributed to the formation of a quasi-one-dimensional antiferromagnetic spin chain, maintaining that each of the vanadium cations is two-dimensionally bridged by hydride and oxide ions. Density functional theory calculations demonstrate that the quasi-one-dimensional property is caused by much enhanced anisotropic exchange couplings $({J}_{1}/{J}_{2}\ensuremath{\sim}6)$ originating from the absence of $\ensuremath{\pi}$ bonding between $\mathrm{H}\phantom{\rule{0.28em}{0ex}}1s$ and $\mathrm{V}\phantom{\rule{0.28em}{0ex}}3d$ orbitals. Utilizing a hydride ion that has an ionic radius similar to an oxygen anion and only one energetically available orbital of $1s$ is a different approach to realization of magnetic low dimensionalization in $3d$ early transition metal oxides.

(n-C3H7)4N[FeIIFeIII(dto)3] shows a new type of first order phase transition called charge-transfer phase transition around 120 K, where the charge transfer between FeII and FeIII occurs reversibly. Recently, we have succeeded in obtaining single crystals of the title complex and determined the crystal structure at room temperature. Crystal data: space group P63, a=10.0618(5) A , c=16.0424(7) A , V=1406.54(12) A 3 , Z=2. Moreover, we have investigated the structural transition caused by the charge-transfer phase transition by means of powder X-ray diffraction measurement. When the temperature is decreased, the a-axis, which corresponds to the hexagonal ring size in two-dimensional honeycomb network structure of [FeIIFeIII(dto)3]∞, contracts by 0.1 A at the charge-transfer transition temperature (TCT), while the c-axis, perpendicular to the honeycomb network layer, elongates by 0.1 A at TCT. Consequently, when the temperature is decreased, the unit cell volume decreases without noticeable anomaly around TCT, which is responsible for the quite small vibrational contribution to the entropy change, compared with usual spin crossover transition. Thus, the charge-transfer phase transition around 120 K for (n-C3H7)4N[FeIIFeIII(dto)3] is regarded as spin entropy driven phase transition.

Crystal structure analysis, transport properties, and ESR study of the new organic conductor (DTEDT) 3 Ag(CN) 2 , where DTEDT is 2-(1,3-dithiol-2-ylidene)-5-(2-ethanediylidene-1,3-dithiole)-1,3,4,6...

High pressure properties of isostructural anion radical salts Me4X(CPDT-TCNQ)2 (X=N, P and As) having extremely one-dimensional electronic structures have been investigated by resistivity and X-ray diffraction measurements. The metal–insulator transition temperature shifted to higher temperature with increasing pressure up to around 9 kbar. The abrupt increases in the resistivity at 9.4 and 7.0 kbar correspond to the appearance of superlattice reflections at room temperature for the Me4P and Me4As salts, respectively. The superlattice reflections were also observed above 7.9 kbar on the Me4N salt. The origins of these transitions are thought to be the 2kF CDW for the Me4N and Me4P salts, and the 4kF CDW for the Me4As salt. In addition, the 4kF to 2kF CDW transition is observed at 10.4 kbar for the Me4As salt.

The vanadium oxide bronzes β(β′)-A x V 2 O 5 of A=Na ( x =0.33), A=Sr ( x =0.33) and A=Cu ( x =0.65) having one-dimensional chain and ladder along the b -axis were studied by X-ray diffraction measurements. We observed the satellite reflections of q =1/2 b ∗ due to A-site cation ordering below 260 K for A=Na and room temperature for A=Sr. And then, we observed the satellite reflections of q =1/6 b ∗ below the metal–insulator transitions of 135 K for A=Na and 165 K for A=Sr. Moreover, we found the reflection accompanying the symmetry breaking below 255 K for A=Cu, corresponding to the slight anomaly in the resistivity of the metallic behavior. The superstructure analyses indicate the characteristic movement of vanadium atoms in the ladder, suggesting the charge disproportionation below 135 K for A=Na and 255 K for A=Cu.

We have performed X-ray diffraction study under pressure for isostructural anion radical salts g '-Et 2 Me 2 Z[Pd(dmit) 2 ] 2 (Z = P, As, Sb) at room temperature. The unit cells remained monoclinic and no satellite reflection was detected up to 18 kbar. For the high-pressure superconductor Et 2 Me 2 P salt, high-pressure crystal structure analyses were carried out. Obtained band parameters indicate an increase of bandwidth and a decrease of the dimensionality of a HOMO-based band. This is related to a pressure-induced metallic state and a non-metallic state in the higher pressure region. molecular conductor metal dithiolene complex crystal structure pressure effect

We have obtained a new molecular metal containing a rare-earth complex anion, g "-(BO) 2 [YbCl 4 (H 2 O) 2 ]. This salt retains metallic conductivity down to 4 K. This crystal is metastable at room temperature; it gradually tranforms into another phase, f -(BO) 2 [YbCl 4 (H 2 O) x ], which becomes insulating below 210 K. The g "-phase crystal have a chain structure of the anions, formed by OH···Cl hydrogen bonding. This is the first example of a ~ molecular conductor based on an assembled rare-earth complex. Preparation, structure and resistivity of (BO) 2 [YbCl 4 (H 2 O) x ] system is reported. Rare-earth molecular conductors structure f -electrons

The title compounds are prepared from mixtures of Rh or Ir, BaS or BaSe, Ge, and S or Se (h-BN capsule, 5 GPa, 1473 K, 2 h).

Structure and chemical features of layered compounds BaM2Ge4Ch6 (M = Rh, Ir; Ch = S, Se) synthesized under high-pressure and high-temperature method are systematically studied. These compounds crystallize in an orthorhombic phase with space group Pbca (No. 61). The remarkable structural feature is to have the M-Ge-Ch pyrite-type building units, stacking with Ba-Ch layers alternatively along c axis. It is very rare and novel that pyrite-type subunits as the building blocks in the layered compounds. Theoretical calculations and experimental results indicate that there are strongly polarized covalent bonds between Ge and Ch atoms, forming heteromolecule-like anions in these compounds. Moreover, Ge atoms in this structure exhibit unusual valence state (~ +1) due to the tetrahedral coordination environment of Ge atoms along with M and Ch atoms simultaneously., 24 pages, 12 figures, 5 tables

Conducting anion radical salts of the metal dithiolene complex Pd(dmit) 2 [dmit = 2-thioxo-1,3-dithiol-4.5-dithiolate] with a series of pyramidal cations Me x Et 3-x Z + (Z = s and Te; x = 0, 1, 2, 3) are described. They exhibit various types of crystal and electronic structures based on the column of strongly dimerized Pd(dmit) 2 units.

Assembled metal complexes, where organic π electrons and metal d electrons coexist, form one important class of materials in the field of molecular metals' and superconductors. Among them, molecular conductors based on metal-dithiolene complexes are known to exhibit various conducting properties. Recent studies on molecular conductors based on the acceptor-type Pd(dmit) 2 [dmit=2-thioxo-1,3-dithiol-4,5-dithiolate] and the donor-type Ni(edo) 2 [edo = ethylenedioxydithiolate] and related materials are deseribed.

In this paper, we report the morphologies of Ni3V2O8 single crystals grown by the flux method in closed and opened crucibles using SrCO3 and V2O5 as flux. Under a high vertical temperature gradient, the morphology of the grown crystals in a closed crucible is found to be pillar-like, which is different from the plate-like feature for crystals grown in an opened crucible. On the basis of the theoretical morphology of Ni3V2O8, the possible reasons for different morphologies in the crucibles are suggested.

Single-crystal structure determination of ${[\mathrm{Zn}(\mathrm{ptz})}_{6}{](\mathrm{B}\mathrm{F}}_{4}{)}_{2}$ has been performed at 110 and 190 K in order to investigate the possible existence of a local structural deformation proposed by positron annihilation study of Nagai et al. [Phys. Rev. B 57, 14 119 (1998)]. A large thermal contraction along the $c$ axis with decreasing temperature is observed, while the displacement of the atoms within the $\mathrm{ab}$ plane is very small. This implies that the effect observed in the positron annihilation spectroscopies is caused by interactions involving positronium.

Lewis acid−base interactions between anions and iodine-containing neutral molecules have been utilized in order to accomplish multicomponent molecular conductors with supramolecular assemblies. In the presence of diiodoacetylene (DIA), p-bis(iodoethynyl)benzene (pBIB), and/or tetraiodoethylene (TIE), several cation-radical salts of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) or ethylenedithiotetrathiafulvalene (EDT-TTF) are prepared by galvanostatic oxidation with such supporting electrolytes as Cl-, Br-, I-, and/or AuBr2-. Crystal structures of these salts solved by the X-ray diffraction method exhibit novel donor (BEDT-TTF or EDT-TTF) arrangements and supramolecular assemblies made of the anions and the neutral molecules (DIA, pBIB, and/or TIE). Transport properties show that these salts range from metal to semiconductor. Several interesting properties such as a curious band dispersion and high anisotropy in resistivity are also observed. Some packing motifs for the description of the supramolecula...

In order to examine Little’s model for organic superconductors, several azulene-substituted TTF derivatives were synthesized. Measurements of the oxidation potentials using cyclic voltammetry (CV) provide their donor abilities. The molecular structure of AET (azulenoethylenedithiotetrathiafulvalene) was determined by X-ray analysis. Cation radical salts of synthesized donors with BF4– , ClO4– , PF6– , AsF6– and [Pt(dmit)2 ]n–(dmit=C3S52–=2-thioxo-1,3-dithiole-4,5-dithiolate) were prepared by galvanostatic electrolyses. Temperature-dependent electrical resistances indicate that these salts are all semiconductive. The crystal structure of (AET)2 [Pt(dmit)2 ] was determined by X-ray analysis and its electronic structure is discussed.

For the first time, large single crystals of lithium divanadate spinel, LiV2O4, showing heavy-fermion behavior down to 20 K, have been grown by a flux method using an effective LiCl–Li2MoO4–LiBO2 solvent system. LiV2O4 belongs to the normal spinel structure type. The V atoms (16d) have octa­hedral coordination [V—O = 1.9709 (7) A] and are arranged in a pyrochlore-type sublattice [V⋯V = 2.9147 (4) A]. The Li atoms (8a) have tetra­hedral coordination [Li—O = 1.9487 (5) A] and are located in channels running parallel to [110].

Low temperature X-ray diffraction study for organic semiconductor (BEDT-TTF)3CuBr4 revealed structural phase transition from P2 1 c to Pc by losing inversion and screw symmetries at 60.2 K where the magnetic susceptibility shows a steep decrease. Abrupt changes in (0 k 0) X-ray reflection intensity and lattice parameters proved that this phase transition has first-order nature. Structure analysis at 65.9 K verified that the average coordination number of Br around Cu is four.

(DIEDO) 2 M(mnt) 2 (M=Ni, Pt; DIEDO=4,5-diiodo-4′,5′-ethylenedioxytetrathiafulvalene; mnt: maleonitriledithiolate) composed of transition metal complexes and iodine-bonded donor have a unique structure featured with strong coordination-bond-like interaction between iodo group of donor and cyano group of anion. It consists of two donor chains sandwiched between anion chains. The salts are metallic down to 100 K, followed by an onset of a metal–insulator (M–I) transition. T MI becomes lowered at high pressures (21 K at P >11 kbar). The magnetic susceptibility suggests the presence of ferromagnetic interactions ( J ∼20 K) between localized magnetic moments of M(mnt) 2 − , which interact with conduction electrons. The origin of ferromagnetic interactions is explained by McConnell’s first model and small overlaps between SOMOs of M(mnt) 2 − .

Isostructural anion radical salts Me 4 X(CPDT-TCNQ) 2 (X=N, P, As) have extremely one-dimensional electronic system. We investigated their high pressure properties from X-ray diffraction measurements. The superlattice reflections were observed at room temperature above 7.9, 12.1 and 9.5 kbar on the Me 4 N, Me 4 P and Me 4 As salts, respectively. They are relevant to the stepwise increase of resistivity under pressure. The origins of the transitions are thought to be the 2 k F CDW for the Me 4 N and Me 4 P salts, and the 4 k F CDW for the Me 4 As salt. In addition, the 4 k F -to-2 k F transition is observed at 10.4 kbar on the Me 4 As salt.

We find anomalously large diamagnetic responses in the cage compounds AV2Al20 where A = Y and La, not A = Al0.3, Sc0.4, and Lu, despite the apparent similarities in crystal and electronic structures among these compounds. The magnetic susceptibilities of the Y and La compounds become -1.94 and -7.44 x 10-4 cm3 mol-1 at 10 K, respectively, the latter of which corresponds to approximately one-quarter of that of bismuth, a well-known diamagnetic material, in terms of unit volume. The origin is not clear but may be related to a specific evolution in the band structure, as the diamagnetic response increases with increasing lattice constant., 5 pages, 4 figures, 1 table; to pe published in J. Phys. Soc. Jpn

A new polymorph of the title compound is hydrothermally synthesized from a solution of CuO and V2O5 in 1% aq, HNO3 (autoclave, 443 K, 10 d).

A new polymorph of volborthite [tricopper(II) divanadium(V) heptaoxide dihydroxide dihydrate], Cu3V2O7(OH)2 2H2O, has been discovered in a single crystal prepared by hydrothermal synthesis. X-ray analysis reveals that the monoclinic structure has the space group C2/c at room temperature, which is different from that of the previously reported C2/m structure. Both structures have Cu3O6(OH)2 layers composed of edge-sharing CuO4(OH)2 octahedra, with V2O7 pillars and water molecules between the layers. The Cu atoms occupy two and three independent crystallographic sites in the C2/m and C2/c structures, respectively, likely giving rise to different magnetic interactions between CuII spins in the kagome lattices embedded in the Cu3O6(OH)2 layers., Comment: 7pages, 2figures

The chemical composition, crystal structure, and magnetic properties of a manganese zinc alloy with an ideal composition of YMn2Zn20, which comprises a pyrochlore lattice made of Mn atoms, are reported. The compound is stable only when In or Al is partially substituted for Zn. We have determined the actual chemical formula as YMn2+dZn20-x-dMx, with M = In or Al, and have identified the characteristic preferences with which the incorporated M and excess Mn atoms occupy the three crystallographic sites for Zn atoms. The Mn atoms in the pyrochlore lattice possess small magnetic moments that interact with each other antiferromagnetically but exhibit no long-range order above 0.4 K, probably owing to the geometrical frustration of the pyrochlore lattice. As a result, the effective mass of the conduction electrons is considerably enhanced, as observed in the related pyrochlore-lattice compounds (Y,Sc)Mn2 and LiV2O4. However, the presence of excess Mn atoms with large localized magnetic moments comparable to spin 5/2 tends to mask the inherent magnetism of the pyrochlore Mn atoms. It is suggested that "YMn2Zn18In2" with neither excess Mn atoms nor site disorder would be an ideal compound for further study., Comment: 19 pages, 18 figures, accepted for publication in J. Solid State Chem

We report aluminium substitution effect on structure and electric properties of langasite (La3Ga5SiO14) family crystals. Quasi-congruent melting composition of La3Ga5-xAlxSiO14 (LGAS), La3Nb0.5Ga5.5-xAlxO14 (LNGA), and La3Ta0.5Ga5.5-xAlxO14 (LTGA) crystals are x = 0.9, 0.2, and 0.5, respectively. A single-crystal x-ray structure analysis reveals that Al atoms are distributed in all cation sites except for the decahedral one occupied by La, by rather favoring the smallest tetrahedral one. The electrical properties of the Al-substituted crystals are compared with those of pure ones. By Al substitution, all langasite family crystals show higher piezoelectric constant d11 and higher electric resistivity ?. Among them, the LTGA crystal with lower temperature dependence of d11 and highest ? is a promising material for high temperature piezoelectric application.

We investigated structure, electronic and magnetic properties of organic conductors with 3d-transition metal halide anions. The crystal structure investigation in (TTM-TTF)CuBr4shows a novel type of nonplanar TTM-TTF2+ structure. Suscep tibilities obey the Curie's law, suggesting the absence of magnet ic interactions between Cu2+magnetic moments. (BEDT-TTF)6Cu2Br6 is a two-dimensional conductor with the mixed valence state of Cu2+/Cu+. A structural transition with a first order nature is found at TC=59K, which is related to the defor mation of CuBr4 2-ligand. The application of pressure modifies the transition to a metal-semiconductor one. An antiferromag-netic long range order accompanied by a short range order is observed at TN=7.5K. This suggests the presence of strong antiferromagnetic interactions achieved by the coupling between Cu2+ localized moments and donor π -electrons.

$\mathrm{K}{\mathrm{Os}}_{2}{\mathrm{O}}_{6}$ with a $\ensuremath{\beta}$-pyrochlore structure undergoes a superconducting transition at ${T}_{c}=9.6\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, which is the highest temperature among a series of compounds, $A{\mathrm{Os}}_{2}{\mathrm{O}}_{6}$ ($A=\mathrm{K}$, Rb, and Cs). In this structure, it is expected that vibrations of the atoms have a large amplitude and a large anharmonicity because an alkali atom is weakly bounded in a large space. On the other hand, $\mathrm{K}{\mathrm{Os}}_{2}{\mathrm{O}}_{6}$ shows another transition at ${T}_{p}=7.5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, which is considered as a structural transition. Moreover, two structures have been reported at room temperature. To investigate structures and anharmonicity of vibrations, Raman scattering spectra of $\mathrm{K}{\mathrm{Os}}_{2}{\mathrm{O}}_{6}$ have been measured from $4\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ to room temperature. Six Raman-active modes are successfully assigned. The assignment concludes that the symmetry at room temperature is $Fd\overline{3}m$, not $F\overline{4}3m$. A vibration of potassium at $70\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ with a ${T}_{2g}$ symmetry clearly shows a large anharmonicity. Moreover, a similar large anharmonicity has also been observed for the oxygen cage modes with the symmetries of ${E}_{g}$ at $260\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ and ${T}_{2g}$ at $240\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$. The electron-lattice interaction is estimated by the linewidth. The strongest interaction is that of the ${T}_{2g}$ mode at $710\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$, which modifies the bond length between osmium and oxygen, and the next one is ${E}_{g}$. The lack of phonon anomaly at ${T}_{c}$ and ${T}_{p}$ suggests that the ${E}_{u}$ mode seems to be important for ${T}_{c}$ and ${T}_{p}$ since this ${E}_{u}$ mode has the low-energy and strong electron-lattice interactions, judging from the similar displacement with the ${E}_{g}$ mode.

We have prepared a single crystal of Ti0.4V 0.6O2 which forms a solid solution crystallizing in the rutile structure at high temperatures and undergoes phase separation due to the spinodal decomposition when cooled to room temperature. The spinodally decomposed crystal consists of a self-assembled, mega stack of alternate Ti- and V-rich layers with an approximate period of 33 nm along the c axis. The unidirectional microstructure causes a large anisotropy in resistivity and a small one in thermal conductivity. A sharp metal–insulator transition as well as a structural transition to a monoclinic structure is observed in the thin V-rich layers.

We report the single-crystal X-ray analysis and magnetic properties of a new double-layered perovskite antiferromagnet, Cs$_3$Cu$_2$Cl$_4$Br$_3$. This structure is composed of Cu$_2$Cl$_4$Br$_3$ double layers with elongated CuCl$_4$Br$_2$ octahedra and is closely related to the Sr$_3$Ti$_2$O$_7$ structure. An as-grown crystal has a singlet ground state with a large excitation gap of $\Delta/k_{\rm B}\simeq 2000$ K, due to the strong antiferromagnetic interaction between the two layers. Cs$_3$Cu$_2$Cl$_4$Br$_3$ undergoes a structural phase transition at $T_{\rm s}\simeq330$ K accompanied by changes in the orbital configurations of Cu$^{2+}$ ions. Once a Cs$_3$Cu$_2$Cl$_4$Br$_3$ crystal is heated above $T_{\rm s}$, its magnetic susceptibility obeys the Curie-Weiss law with decreasing temperature even below $T_{\rm s}$ and does not exhibit anomalies at $T_{\rm s}$. This implies that in the heated crystal, the orbital state of the high-temperature phase remains unchanged below $T_{\rm s}$, and thus, this orbital state is the metastable state. The structural phase transition at $T_{\rm s}$ is characterized as an order-disorder transition of Cu$^{2+}$ orbitals., Comment: 6pages. 6figures, to appear in J. Phys. Soc. Jpn. Vol.76 No.1

Low-temperature crystal structure and optical properties of the quasi-one-dimensional organic conductor (ChTM-TTP) 2 GaCl 4 (ChTM-TTP: 2-[4,5-(1,2-cyclohexylenedithio)-1,3-dithiol-2-ylidene]-5-[4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-1,3,4,6-tetrathiapentalene) have been investigated. As the temperature lowers, the disordered anion transforms to an ordered state with a superstructure wave vector of \(\mbi{q}=(\frac{1}{2}, 0, \frac{1}{2})\). The peak intensities of the superlattice gradually increase in the metallic region, and are saturated below 150 K; this indicates that the charge localization below 150 K is independent of the evolution of the superlattice. The reflectance spectra of (ChTM-TTP) 2 X suggest the existence of moderate interchain interactions. The transverse interactions are more pronounced in the GaCl 4 salt ( t ⊥ / t || ≈1/7) than the AuBr 2 and Au(CN) 2 salts. The low-temperature optical reflectance of the GaCl 4 salt shows no significant change, indicating that (ChTM-TTP) 2 GaCl 4 g...

Crystal structure analyses, measurements of transport and magnetic properties, and low-temperature X-ray studies of new organic conductors: (ChTM-TTP)2AuBr2, (ChTM-TTP)2GaCl4, and (ChTM-TTP)ReO4, where ChTM-TTP is 2-[4,5-(1,2-cyclohexylenedithio)-1,3-dithiol-2-ylidene]-5-[4,5-bis (methylthio)-1,3-dithiol-2-ylidene]-1,3,4,6-tetrathiapentalene, have been carried out. In these compounds, the donors form quasi-one-dimensional columns with dimerization induced by the steric hindrance of the 1,2-cyclohexylene unit. The crystal structures and the energy band structures of both AuBr2- and GaCl4- salts are similar to those of the Bechgaard salts. The electrical resistivity and the thermoelectric power show metallic behavior above 100 K for the AuBr2- salt and above 150 K for the GaCl4- salt. The results of the ESR spin susceptibility, the static magnetic susceptibility, and the low-temperature X-ray studies indicate that the ground states of both salts are antiferromagnetic insulators. The Neel temperatures are ab...

Vibrations of alkaline guest atom A in β -pyrochlore oxides AOs2O6 (A = K, Rb, and Cs) are analyzed by a simple interaction model, where interatomic force constants between A atoms k ( AA ) and between A atom and cage k ( AC ) are employed. The obtained coefficients show that A atoms vibrate in highly anharmonic potential with strong interactions between A atoms. Especially for K atoms in KOs2O6, its potential can be approximately described only by fourth-order term.