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The two-dimensional quadratic lattice magnet, bis(glycolato)cobalt(II) ([Co(HOCH2CO2)2]), showed antiferromagnetic ordering at 15.0 K and an abrupt increase in magnetisation at H = 22 600 Oe and 2 K, thereby acting as a metamagnet. Heat capacity measurements revealed that the associated entropy change ΔS around the transition temperature was evaluated to be 6.20 J K−1 mol−1 and that the Co(II) ion had the total angular momentum of J = 1/2 at low temperatures. Neutron diffraction studies suggested that the magnetic moment vectors of the Co(II) ions had an amplitude of 3.59μB and were not aligned in a fully antiparallel fashion to those of their neighbours, which caused canting between the magnetic moment vectors in the sheet. The canting angle was determined to be 7.1°. Canting induced net magnetisation in the sheet, but this magnetisation was cancelled between sheets. The magnetisations in the sheets were oriented parallel to the magnetic field at the critical magnetic field.

A simplified J-integral evaluation method applicable to unstable failure analysis in Leak Before Break (LBB) assessment of Sodium-cooled Fast Reactor (SFR) in Japan was proposed. Mod.9Cr-1Mo steel is supposed to be a candidate material for the coolant systems of SFR in Japan. This steel has relatively high yield strength and poor fracture toughness comparing to those of conventional austenitic stainless steels. In addition, SFR pipe has small thickness and large diameter. Furthermore, in SFR, primary stresses are insignificant and displacement controlled secondary stresses are predominant. Therefore, the load balance in such piping system changes by crack extension and R6 (2-parameter) method (hereinafter “2-parameter method”) [1] using J-integral is applicable to unstable failure analysis for the pipes under such loading conditions. As a J-integral evaluation method for circumferential through-wall crack in a cylinder, EPRI has proposed a fully plastic solution method. However, the geometry of SFR pipe and material characteristics of Mod.9Cr-1Mo steel exceed the applicable range of EPRI’s method. Therefore, a series of elastic, elasto-plastic and plastic finite element analyses (FEA) were performed for a pipe with a circumferential through-wall crack to propose a J-integral evaluation method applicable to such loading conditions. J-integrals obtained from the FEA were resolved into elastic, local plastic and fully plastic components. Each component was expressed as a function of analytical parameter, such as pipe geometries, crack size, material characteristics and so on. As a result, a simplified J-integral evaluation method was proposed. The method enables to conduct 2-parameter method using J-integral without any fracture mechanics knowledge.

The effect of ratcheting deformation on fatigue and creep–fatigue life in Mod.9Cr–1Mo steel was investigated. Uniaxial fatigue and creep–fatigue testing with superimposed strain were performed to evaluate the effect of ratcheting deformation on the failure cycle. In a series of tests, a specific amount of superimposed strain was accumulated in each cycle. The accumulated strain as ratcheting deformation, cycles to reach the accumulated strain, and test temperatures were varied in the tests. In the fatigue tests with superimposed strain at 550 °C, slight reductions of failure lives were observed. All of the numbers of cycles to failure in the fatigue tests with superimposed strain were within a factor of 1.5 of that of the fatigue test without superimposed strain at 550 °C. The apparent relationship between failure cycles and testing parameters was not observed. In fatigue tests with superimposed strain at 550 °C, maximum mean stress was insignificant and generated in early cycles because Mod.9Cr–1Mo steel exhibits cyclic softening characteristics. It was assumed that suppression of mean stress generation by cyclic softening reduces the effect of ratcheting strain. Conversely, failure lives were increased by accumulated strain in the test conducted at 450 °C because of stress–strain hysteresis loop shrinkage caused by cyclic softening induced by the accumulated strain. In the creep–fatigue tests with superimposed strain, test results indicated that the accumulated stain was negligible. It was concluded that the effect of ratcheting deformation on fatigue and creep–fatigue life is negligible as long the parameters are within strain limits of the design and construction code for fast reactors (inelastic strain at surface

The effect of ratcheting deformation and pre-strain on fatigue and creep-fatigue life in Mod.9Cr-1Mo steel was investigated. Uni-axial fatigue and creep-fatigue tests with pre-strain and progressive strain were performed to evaluate the effect of pre-strain and ratcheting strain on the failure cycle. In a series of tests, a specific amount of progressive strain was accumulated in each cycle. The accumulated strain as ratcheting deformation and cycles to reach the accumulated strain were varied in the tests. In the fatigue tests with pre-strain, failure lives were not declined. In the fatigue tests with progressive strain, slight reductions of failure lives were observed, however, they were within a factor of 1.5 of the failure life in normal fatigue test. The apparent relationship between failure cycles and testing parameters were not observed. Analyses of the test results indicated that the effect of ratcheting strain on the fatigue failure life is negligible as long as the parameters are within the strain limit of FR code (strains at surface less than 2%). In the creep-fatigue tests with progressive strain, the same conclusion of the fatigue tests was obtained. In both kinds of tests, maximum mean stresses during the tests were insignificant and/or generated in early cycle in the tests, and this character is considered as a reason of that the effect of ratcheting deformation on the fatigue and creep-fatigue lives are insignificant.

New C60-TTF dyads with several substituents on the TTF moiety were prepared to examine the substituent effect on the intramolecular charge transfer interaction. Cast films of the dyads with long alkyl chains were obtained with high quality and characterized. In X-ray diffraction study for the cast film of the derivative with -SC16H33 groups ( 1g ), high ordered reflection peaks were observed. Analysis of the diffraction pattern revealed that 1g forms the multibilayer structure in condensed film.

The synthesis of dihydrotetrathiafulvalene (DHTTF) donors and the preparation of their charge-transfer (CT) salts have been undertaken to develop new organic metals and superconductors. The molecular structures of methylenedithio-DHTTF (MDHT), 1,4-dioxane-2,3-diyldithio-DHTTF (DODHT), and methylmethylidenedithio-DHTTF (Me-MDHT) are secured by X-ray crystallographic analyses. These DHTTF donors provide CT salts characterized by a wide range of conducting behavior from semiconducting to metallic and superconducting. The crystal structures of CT salts from each category are described.

Creep behavior of the 6061 aluminum alloy matrix composite reinforced by 10 vol.% of alumina particles has been investigated at temperatures from 573 to 773 K in air and Ar atmospheres. Creep curves, stress dependence of the minimum creep rate, microstructures after creep deformation and the effect of the atmospheres on the creep behavior were examined. Deformation around grain boundaries was estimated by measuring the offset of marking lines across grain boundaries. Creep curves were dominated generally by tertiary creep in air and Ar at every temperature except in extremely low stress range at 773 K, where primary creep dominated. Large primary creep strain following an initial inverse type of transient creep was observed in air in the low stress range at 773 K. The effect of atmosphere was prominent only in the primary creep stage under extremely low stresses at high temperature. In the stage, large decrease in density and large deformation around grain boundaries with creep deformation in air were observed. Many voids and cracks were observed on the surface of the specimen crept in low stress range at 773 K in air. Filament like structures, which were seen to generate at particle-matrix interfaces or grain boundaries, were often observed on the fracture surfaces under the condition. Extremely high density of magnesium and oxygen was detected at the filament like structure by energy-dispersive X-ray spectrometry. The effects of the oxidation and the formation of the filament like structure on the creep behavior are discussed.

Supramolecular assemblages made of single wall carbon nanotubes (SWNT) filled with fullerenes or metal doped fullerenes exhibit promising electronic structure variations at a nanometer scale. Nevertheless, the knowledge about the structural defects of these systems is still very limited. Here, we report structural evolutions under high-resolution electron microscopic observation at the sensitivity of a single atom detection for Ca@C82 molecules encapsulated within SWNT.

Successive metal–insulator transitions in (DIMET) 2 BF 4 were studied by chopped-light ac calorimetry and electron paramagnetic resonance (EPR) measurement. An anomaly due to the metal–insulator transitions has been clearly detected in ac calorimetry between 20 and 35 K. In contrast to other double-column salts (DMET) 2 BF 4 and (DMET) 2 ClO 4 , successive metal–insulator transitions detected in transport properties are shown to be thermodynamic phase transitions. The EPR detected an anomaly only for the lowest transition around 12 K. The properties of the metal–insulator transitions are compared among the DIMET and DMET salts having the double-column structure. A frequency-dependent step in heat capacity was detected around 110 K. The step-like anomaly is attributed to a glass transition due to freezing of the intramolecular motion of the ethylene group in the ET moiety within a DIMET molecule.

Heat capacity of a quasi-one-dimensional organic conductor (DIMET) 2 I 3 has been measured by chopped-light ac calorimetry below room temperature. An anomaly due to a metal-insulator transition has been clearly detected around 40 K. The magnitude of the anomaly is analyzed through comparison with other Q1D conductors. A possible SDW mechanism is suggested.

Temperature dependence of the heat capacities of two organic conductors, (DMET) 2 BF 4 and (DMET) 2 ClO 4 , was measured by chopped-light ac calorimetry between 10 and 300 K. A “Mott-like” nature o...

Synchrotron x-ray powder diffraction experiments of a fullerene C 76 crystal have elucidated its structure and successive phase transitions for the first time. Two types of crystal lattices, fcc and hexagonal ones, coexist through the temperature range investigated between 10 K and 550 K. Both precise analysis of diffraction patterns as a function of temperature and structural model calculations reveal successive phase transitions at 140 ±10 K and 420 ±10 K associated with degrees of molecular orientations for the hexagonal lattice. The fcc lattice undergoes a similar phase transition at 140 ±10 K. By applying pressure and analyzing lattice constants we also study compression and pressure-temperature phase diagram of this crystal.

We describe the first chemical derivation of endohedral metallofullerenes giving the corresponding exohedral adducts. For example, mass spectrometry and electron paramagnetic resonance (EPR) spectroscopy provide evidence for the formation of chemical derived La@C82 with disilirane (disilacyclopropane). An interesting salient feature of La@C82 is discovered. Although disilirane does not add thermally onto the empty fullerenes such as c60 and C82, a facile thermal addition to La@C82 takes place. Other derivatives of metallofullernes will also be discussed.

The magnetoresistance of a quasi-one-dimensional (Q1D) organic superconductor, (DMET) 2 I 3 , where DMET is dimethyl(ethylenedithio)diselenadithiafulvalene, was measured up to 30 T at 1.5 K. An electrical current was applied perpendicular to the conducting a b plane and a magnetic field is rotated in the a b plane. An anomalous hump of the magnetoresistance reported previously was observed at 7 T between -15° and 15° from the most conducting b -axis. It was found that the hump has a fine structure at higher magnetic fields with two additional sharp local minima at about ±3°. Partial disappearance of the Q1D Fermi surface at a critical angle, where a kind of quantum limit is realized, is proposed to interpret the fine structure.

Comparative study is presented for the in-plane angular effect of magnetoresistance of quasi-one-dimensional organic conductors, (DMET) 2 AuBr 2 and (TMTSF) 2 ClO 4 . The magnetoresistance for the magnetic and electrical fields parallel and perpendicular to the most conducting plane, respectively, was measured at 4.2 K and up to 7.0 T. (DMET) 2 AuBr 2 shows an anomalous hump in the field-orientation dependence of the magnetoresistance for the magnetic field nearly parallel to the most conducting axis and this is very similar to what previously reported for (DMET) 2 I 3 . Weak anomaly was detected for the magnetoresistance of (TMTSF) 2 ClO 4 in the Relaxed state, while no anomaly was observed in the SDW phase in the Quenched state. By comparing the numerical angular derivatives of the magnetoresistance, it is shown that the anomaly in the in-plane angular effect continuously develops from zero magnetic field and is closely related to the quasi-one-dimensional Fermi surface. A simple method is proposed to e...

This paper proposes provisional welded joint strength reduction factors (WJSRF) of modified 9Cr-1Mo steel (ASME Gr.91) applicable to the structural designing of “Japan sodium cooled fast reactor (JSFR)”. In the welded joints of creep strength enhanced ferritic steels including modified 9Cr-1Mo steel, creep strength may obviously degrade especially in long-term region. This phenomenon is known as “Type-IV” damage. The authors had proposed provisional allowable stress for the welded joints made of the steel in PVP 2010 conference, taking creep strength degradation due to “Type-IV” damage into account. Available creep rupture data of the welded joints made of the steel provided by Japanese steel venders were collected. The temperature range was from 500 to 650°C. The database was analyzed by stress range partitioning method. The creep rupture data were divided into two regions of short-term and long-term and those were individually evaluated by regression analyses with Larson Miller Parameter (LMP). The difference in the creep failure mechanisms between short-term and long-term regions is taken into account in this method. Boundary between these regions was half of 0.2% proof stress of the base metal at corresponding temperature. First order polynomial equation of logarithm stress was applied. For conservativeness, allowable stress was proposed provisionally considering design factor for each region. JSME (Japan Society of Mechanical Engineers) published a revised version of the elevated temperature design code in last year. Modified 9Cr-1Mo steel was officially registered in the code as a new structural material for sodium cooled fast reactors. The creep rupture curve for the base metal of the steel was standardized by employing stress range partitioning method, same as for the welded joint. However, second order polynomial equation of logarithm stress was applied in the analysis for the base metal. In addition, the creep rupture data obtained at 700°C were included in the database and data ruptured in very short term, i.e. smaller than 100 hours, were excluded from the analysis. Thus, there are some differences between the procedures to determine the creep rupture curves for base metal and welded joint made of modified 9Cr-1Mo steel. This paper discusses the most feasible procedure to determine the creep rupture curve of the welded joint of the steel by performing some case studies to focus on physical adequacy and harmonization with the determination procedure of the creep rupture curve for the base metal. Then, the WJSRF are provisionally proposed based on the design creep rupture stress intensities. In addition, the design of JSFR pipes was reviewed taking WJSRF into account.Copyright © 2013 by ASME

Ultraviolet photoelectron spectra (UPS) of GdC82 and La2C80 were measured using synchrotron radiation. The specimens for the measurement were not evaporated films but drying up films obtained from the metal fullerene solutions. Although the effect of the contamination to the specimens remains even after heat treatment, the UPS of the GdC82 film show several characteristic structures that are essentially identical to those of LaC82. This suggests that the interaction between the GdC82 molecules are small and GdC82 can be treated as a molecular crystal. The spectrum of La2C80 differs from those of other fullerenes, which indicates either that the interaction among the La2C80 molecules are too large to give a sharp spectrum or that the molecule does not have so-called cage structure.

Photoluminescence spectra of mechanically damaged C60 single crystals were investigated. Two main spectral peaks were observed at 685 and 735 nm, which originate from structural defects, such as dislocations, introduced near the crystal surface and in a perfect region of the crystal, respectively.

Angular dependence of magnetoresistance of a quasi-one-dimensional organic superconductor, (DMET) 2 I 3 has been measured at 4.2 K for magnetic fields up to 7.0 T. For the field of 1.0 T, the angular dependence of the magnetoresistance is smooth over the entire range of angles, reflecting the quasi-one-dimensional band structure of the salt. When the magnetic field of 7.0 T was rotated in the most conducting a b plane, the magnetoresistance for the current along both the b- and c * -axes showed discontinuous changes in its slope at the angles of ±15° from the most conducting axis. The anomaly occurring at 7.0 T is considered to be due to a change in electronic state induced by the magnetic field almost perpendicular to the quasi-1D Fermi surface.

In the photoconductance spectrum of a ${\mathrm{C}}_{60}$ single crystal, a pronounced peak is found near 1.65 eV, corresponding to the weak absorption band. It is discriminated from the broad photoconductance band appearing above 1.8 eV, in its temperature and irradiation intensity dependences. The photoconductance exhibits a superlinear dependence in contrast to the sublinear one appearing above 1.8 eV. The electronic states related to the photoconductance and the effects of crystalline imperfections are discussed.

In a component design at elevated temperature, fatigue and creep-fatigue is one of the most important failure modes, and fatigue and creep-fatigue life assessment in structural discontinuities is important issue to evaluate structural integrity of the components. Therefore, to assess the failure estimation methods, cyclic thermal loading tests with two kinds of cylindrical models with thick part were performed by using an induction heating coil and pressurized cooling air. In the tests, crack initiation and propagation processes at stress concentration area were observed by replica method. Besides those, finite element analysis (FEA) was carried out to estimate the number of cycles to failure. In the first test, a shorter life than predicted based on axisymmetric analysis. Through the 3 dimensional FEA, Vickers hardness test and deformation measurements after the test, it was suggested that inhomogeneous temperature distribution in hoop direction resulted in such precocious failure. Then, the second test was performed after improvement of temperature distribution. As a result, the crack initiation life was in a good agreement with the FEA result by considering the short term compressive holding. Through these test and FEA results, fatigue and creep-fatigue life assessment methods of Mod.9Cr-1Mo steel including evaluation of cyclic thermal loading, short term compressive holding and failure criterion, were discussed. In addition it was pointed out that the temperature condition should be carefully controlled and measured in the structural test with Mod.9Cr-1Mo steel structure.Copyright © 2012 by ASME

Submicrometer-thick ${\mathrm{C}}_{76}$ films were prepared by vacuum deposition on air-cleaved mica and NaCl substrates held at 430 K, and the crystal structure and textures of the films were studied by transmission electron microscopy (TEM). ${\mathrm{C}}_{76}$ formed the fcc lattice with a lattice parameter a=1.53\ifmmode\pm\else\textpm\fi{}0.02 nm on both substrates. A film grown on mica exhibited a single-crystalline pattern in electron diffraction, though local variations in thickness and orientation were suggested by high-resolution TEM. On NaCl, polycrystalline films consisting of small grains (10--20 nm) were formed. Electron diffraction experiments at low temperatures showed no structural transformation down to 110 K.

For sodium pipes of Japan Sodium cooled Fast Reactor (JSFR), the continuous leak monitoring will be adopted as an alternative to a volumetric test of the weld joints under conditions that satisfy Leak-Before-Break (LBB). The sodium pipes are made of ASME Gr.91 (modified 9Cr-1Mo) steel. Thickness of the pipes is small, because the internal pressure is very low. Modified 9Cr-1Mo steel has a relatively large yield stress and small work hardening coefficient comparing to the austenitic stainless steels which are currently used in the conventional plants. In order to discuss about the LBB of the sodium pipes made of modified 9Cr-1Mo steel, the coolant leak rate from a through wall crack must be estimated properly. Since the leak rate is strongly related to the crack opening displacement (COD), an appropriate COD assessment method must be established to perform LBB assessment. However, COD assessment method applicable for JSFR sodium pipes — thin wall and small work hardening material — has not been proposed yet. Therefore, the authors have proposed a COD assessment method applicable to thin walled large diameter pipe made of modified 9Cr-1Mo steel. In this method, COD is calculated by classifying into three components of elastic, local plastic and fully plastic. This paper describes the improved COD assessment method and verifies the validity of the method based on the results of a series of four-point bending tests at elevated temperature using thin wall modified 9Cr-1Mo steel pipe containing a circumferential through wall crack. As a result, COD values calculated by the proposed method were in a good agreement with the experimental results for the uniform pipe without weld. In the case that the crack was machined at weld metal or heat affected zone (HAZ), proposed method predicted relatively larger COD than the experimental results. The causes of such discrepancies were discussed comparing with the results of finite element analyses. Based on these examinations, the rational leak rate evaluation method in LBB assessment was proposed.Copyright © 2011 by ASME

For sodium pipes of Japan Sodium cooled Fast Reactor (JSFR), the continuous leak monitoring will be adopted as an alternative to a volumetric test of the weld joints under conditions that satisfy Leak-Before-Break (LBB). The vessels of JSFR are connected by thin wall pipes with a large diameter made of modified 9Cr-1Mo steel and the internal pressure of the pipes is very low. Modified 9Cr-1Mo steel has relatively large yield stress and small work hardening coefficient compared to the austenitic stainless steels which are currently used in the conventional plants. Therefore, these material characteristics of modified 9Cr-1Mo steel must be taken into account in LBB assessment, as well as geometrical and structural features of JSFR pipes. In order to demonstrate LBB aspects of the JSFR pipes, the authors have proposed a LBB assessment flowchart and developed assessment methods of unstable fracture and crack opening displacement (COD) for the thin wall pipes with large diameter made of modified 9Cr-1Mo steel. This paper studies the master curve to estimate the crack length when a postulated initial crack unexpectedly grows and penetrates the pipe thickness. In order to obtain the fatigue crack and creep crack growth characteristics of modified 9Cr-1Mo steel pipes, fatigue crack and creep crack growth tests were conducted using compact tension (CT) specimens and crack growth rates for both fatigue and creep at elevated temperature were obtained. Based on the obtained material characteristics and the results of a series of crack growth calculations, a relationship between the penetrated crack length and the ratio of membrane to total stress, so called as master curve, was proposed. In this study, master curves were proposed for pipes made of modified 9Cr-1Mo steel as a function of pipe geometry, i.e. the ratio of radius to thickness.Copyright © 2011 by ASME

Optical properties of fcc C 60 samples have been studied by using photoacoustic spectroscopy over the temperature range 30–300 K. A sharp absorption edge is seen at 1.7 eV at room temperature. The optical absorption spectrum changes drastically at 80 K. Another change of absorption spectrum is also observed at 260 K. These changes can be explained by the molecular motion of C 60 .

Electronic structures of various kinds of alkali metal (Na, K, Rb or Cs)-doped C 60 solids are studied by electrical resistivity and thermoelectric power measurements by using C 60 single crystals prepared from a CS 2 solution as a starting material. For K-or Rb-doped C 60, metallic conducting behaviors in the normal conducting state and relatively sharp superconducting transitions are observed by the electrical resistivity measurements. Nearly linear-temperature dependences with the negative sign are observed in the thermoelectric power measurements at the normal conducting states for K-or Rb-doped C 60. From electron diffusion term of the thermoelectric power, the values of Fermi energy and the density of states at the Fermi energy are estimated by assuming the three-dimensional free electron model, which are in substantial agreement with the results of other experiments and calculations. "Metal–semiconductor transition" is observed in both the electrical resistivity and the thermoelectric power measurements for Na-doped C 60. Existence of metallic phase is confirmed by the thermoelectric power measurement in Cs-doped C 60.

Magnetic properties of Cs x C60 have been studies by the magnetic susceptibility and ESR. The observation of Pauli and Curie-Weiss susceptibilities implies the existence of a metallic phase Cs1C60 and a paramagnetic phase Cs4C60.

Thin films of ${\mathrm{C}}_{84}$, ${\mathrm{C}}_{82}$, ${\mathrm{C}}_{78}$, ${\mathrm{C}}_{76}$, and ${\mathrm{C}}_{70}$ grown on cleaved GaAs(110) were studied with scanning tunneling microscopy. Well-ordered two-dimensional arrays were formed at submonolayer molecular coverage for each fullerene. High-resolution imaging of ${\mathrm{C}}_{84}$ revealed intramolecular features that we attribute to atomic features on the fullerene cage. Variations in the symmetry of these structures reflect differences in the molecular orientation. Similar intramolecular features were observed for ${\mathrm{C}}_{82}$ but none were imaged for ${\mathrm{C}}_{78}$, ${\mathrm{C}}_{76}$, and ${\mathrm{C}}_{70}$, implying that substrate interaction is less restrictive and the fullerenes rotate at 300 K.

13 C NMR (nuclear magnetic resonance) in C 70 solid was observed between 77 K and 340 K. Clear evidence of a phase transition around 280 K and anisotropic molecular rotation was found in a sublimed C 70 solid with purity of more than ∼ 99%. It was observed that the sample quality significantly affects the C 70 molecular dynamics.

The thermopowers of (DMET) 2 AuI 2 and (DMET) 2 Au(CN) 2 were measured between liquid helium and room temperatures. In addition to the metallic thermopower above the SDW transition temperature (16 and 24 K for (DMET) 2 AuI 2 and (DMET) 2 Au(CN) 2 , respectively), a large excess contribution probably due to the SDW fluctuation was detected below about 70 K.

Magnetic properties of C 60 and C 70 complexes with tetrakis(dimethylamino)ethylene (TDAE) have been studied based on the measurements of the Faraday-balance magnetization and the electron-spin resonance (ESR). It has been found that both TDAE-C 60 and TDAE-C 70 possess about one radical spin per fullerene molecule. TDAE-C 60 has been confirmed to show a ferromagnetic-type transition at T c =16.7-17.5 K. Appearance of a broad and intense ESR signal below T c for TDAE-C 60 suggests that the radical spins in the magnetically ordered state are rather localized on each C 60 molecule and are ferromagnetism at temperatures above 4.5 K

X ray photoemission spectra show ∼10 valence band features in C60 and C84 films, although they are less distinct in C84 because of the increased number of valence electrons and the decreased molecular symmetry. The presence of inequivalent carbon atoms in C84 is reflected by the fact that the C 1s main line is ∼0.2 eV wider than in C60. The C 1s satellite region of C84 exhibits four features within 15 eV of the main line and shows that the HOMO-LUMO π-π* excitation energy of C84 is ∼0.5 eV smaller than in C60. Potassium 2p spectra for K-doped C84 films suggest the formation of a phase with composition K3C84 with two spectroscopically-distinguishable K sites. A new spectral feature emerges when the K content is increased beyond K3C84, suggesting a phase transition and a saturated composition of K6C84, as for KxC60. These similarities are intriguing since KxC84 is insulating for all x while K3C60 is metallic and superconducting.

Magnetic properties of C 60 and C 70 complexes with tetrakis(dimethylamino)ethylene (TDAE) have been studied based on the measurements of the Faraday-balance magnetization and the electron spin resonance (ESR). It has been found that both TDAE- C 60 and TDAE- C 70 possess about one radical spin per fullerene molecule. TDAE- C 60 has been confirmed to show ferromagnetic-type transition at Tc=16.7–17.5 K . Appearance of a new broad and intense ESR signal below Tc of TDAE- C 60 suggests that the radical spins in the magnetically ordered state rather localize on each C 60 molecule and are ferromagnetically correlated. On the other hand, TDAE- C 70 does not show ferromagnetism in all the temperature range down to 4.5K.

The thermoelectric power of (DMET)2X was measured, where X is PF6, AsF6, BF4, I3, SCN, or AuBr2. In accordance with the classification of the DMET family, the salt in different group showed different temperature dependence in thermoelectric power.

The thermal conductivity (κ) of (DMET)2AuI2 (DMET = dimethyl(ethylenedithio)diselenadithiafulvalene) was measured between 10 and 300 K for the first time as a quasi-one-dimensional organic conductor based on the DMET molecule. The material is very similar to the first organic superconductor (TMTSF)2PF6 (TMTSF = tetramethyltetraselenafulvalene); the DMET salt undergoes the spin-density-wave transition at 16 K at ambient pressure, but becomes superconducting below 0.5 K above 0.5 GPa. It was found that κ of (DMET)2AuI2 has anomalies at 25 and 70 K as well as the unusual upturn above 200 K. It is shown that the temperature dependence of κ below 200 K can be phenomenologically reproduced by combining two terms of the Debye type lattice thermal conductivity and the electronic thermal conductivity.

Radioactive endohedral {sup 7}Be@C{sub 60} can be detected using radiochemical and radiochromatographic techniques in the final solvent. Such a {sup 7}Be atom can penetrate into the C{sub 60} cage to produce {sup 7}Be@C{sub 60} by a recoil process of the nuclear reactions. An {ital ab} {ital initio} molecular dynamics simulation was carried out to demonstrate that a direct insertion process is really possible. Both the experimental and the theoretical results were consistent with each other. {copyright} {ital 1996 The American Physical Society.}

In addition to two organic superconductors (DODHT)2X [DODHT = (1,4-dioxane-2,3-diyldithio)dihydrotetrathiafulvalene; X = PF6 and AsF6] previously reported by us, the BF4 salt of DODHT containing one water molecule [(DODHT)2BF4 x H2O] has been found to undergo a superconducting transition at 3.2 K under a hydrostatic pressure of 15.5 kbar.

Ternary-alkali-metal-intercalated fullerides, KRbCsC 60 , was prepared by method employing alkali metal azides reported by Bensebaa et al . (F. Bensebaa, B. Xiang and L. Kevan: J. Phys. Chem. 96 (1992) 6118). We found that KRbCsC 60 is a superconductor with the transitipn temperature of 28(bulk)∼29 K (onset). It was also found, from nuclear magnetic resonance (NMR) study of 87 Rb and 133 Cs in this system, that the alkali atoms are site-selectively intercalated into C 60 face-centered-cubic (fcc) lattice. The largest alkali-metal ion, Cs, occupies octahedral sites of the C 60 fcc lattice, and the K and Rb atoms occupy mainly tetrahedral sites.

The iron atoms in the SWNTs soot produced from a carbon rod with Fe-Ni metal by the arc-discharge method were studied for their chemical species by Mossbauer spectroscopy. They were found present as a mixture of some Fe-Ni alloys and the α-Fe metal particles of sizes more than 10 nm that were dispersed. No change was observed in the Mossbauer spectra by the treatment of the soot with 1 M HCl but a drastic temperature dependence of the spectra observed for the samples burned in air indicated that more than 50% of the iron was oxidized to Fe2O3 in small particles of less than 10 nm. Effects of acid leaching and baking commonly used for separation of SWNTs were quantitatively studied by use of a radiotracer. Effectiveness of various kinds of metal atoms for forming nanonetwork materials were also investigated by taking advantage of the use of multi-radiotracers. A clear dependence of the yield of metal-containing fullerene species on the boiling point of the metal was indicated, and the yields were found sen...

The thermoelectric power of K- and Rb-doped C 60 superconductors prepared from single crystals grown from a CS 2 solution is reported. Nearly linear temperature dependences of the thermoelectric power with negative sign are observed above the superconducting transition temperatures for both materials. From the slope of the linear correlation, the ratio of the density of states at the Fermi energy, N Rb (E F )/N K (E F ), is estimated to be 1.5-1.8

Characterizable amount of La@C80 was prepared by means of a two-stage HPLC purification of fullerene ingredients which were extracted from carbon soot in macroscopic quantity. In the same way as the investigation of Ce@C82 and CeLa@C80 in our previous work, molecular dynamic behavior of the newly purified species has been studied by means of time-differential perturbed angular correlation measurements. The data analyzed have shown that powder Ce@C80 has somewhat slow rotational motion at room temperature compared with Ce@C82 of the same form and the electric field gradient at the encaged Ce nucleus is almost equal to that at the corresponding atom of Ce@C82.

The pressure-induced organic superconductor β-(BDA-TTP)2FeCl4 [BDA-TTP = 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene], which shows a metal–insulator (MI) transition at \(T_{\text{MI}} = 113\) K under ambient pressure, has been found by X-ray study to have a two-fold crystal structure along the \(c\)-axis in the insulating state at 10 K. In the donor layer, there are four independent BDA-TTP molecules, which are divided into two charge-poor ones and two charge-rich ones on the basis of the folding dihedral angles around the intramolecular sulfur-to-sulfur axes of two outer dithiane rings in BDA-TTP. The charge separation leads to the formation of two types of dimers: a dimer consisting of two charge-poor donors and a dimer consisting of two charge-rich ones. The tight-binding band calculation revealed a band gap of 5.3 meV in the energy dispersion. The MI transition can be therefore accounted for by the charge separation. In addition, we investigated the crystal and electronic structures of β...

A coordination polymer with a two-dimensional square planar lattice network, bis(glycolato)copper(II), shows a large structural phase transition at around 220 K and ferromagnetic ordering at 1.1 K.