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Muon-spin rotation (mu SR) measurements have been used to study the superconducting vortex properties of the organic superconductors kappa-(BEDT-TTTF)(2) Cu(SCN)(2), alpha-(BEDT-TTF)(2) NH4Hg(SCN)(4) and beta-(BEDT-TTF)(2)IBr2. These materials all have highly anisotropic structures consisting of metallic layers of BEDT-TTF molecules alternating with less well conducting anion layers. Varying the anion gives rise to a change in the anisotropy of the superconductivity and also to changes in the superconducting transition temperature. We have used both transverse and longitudinal magnetic fields to study the three-dimensional flux line lattice that is present at low temperatures and fields and to study also the loss of flux lattice order that occurs on increasing the temperature and field. (C) 2000 Elsevier Science B.V. All rights reserved.

Four types of functionalized 3,3'-bicarbazole derivatives are prepared and investigated as a host material for blue phosphorescent OLEDs. By using a 3,3'-bicarbazole derivative/FIrpic film as an emissive layer, high power efficiency of 46 lm W(-1) (45 cd A(-1), EQE 20%) with an extremely low driving voltage at 3.1 V is obtained at 100 cd m(-2).

We have investigated the 45 GHz microwave response from an organic superconductor λ-(BEDT-TSF)2GaCl4 with T c = 4.8 K. In the superconducting state, the London penetration depth saturates well below T c , which may provide an evidence for a conventional s-wave paring. In the metallic state, σ 1 c deviates downward from σ dc c , while σ 2 c , which should be zero in a conventional metallic state, increases exponentially toward T c . This anomalous metallic state has been discussed in terms of a possible formation of incoherent electron pairs in so-called a pseudogap state.

We performed precise X-ray diffraction measurements on an organic conductor, λ-(BETS) 2 FeCl 4 , with synchrotron radiation, where BETS is bis(ethylendithio)tetraselenafulvalene. Around 70 K (= T FM ), the width of the Bragg reflection increased, and its peak was split into two with decreasing temperature. The direction of splitting was 0.017 a * - 0.010 b * + 0.002 c * in the reciprocal space. At 8.3 K (= T MI ), the discontinuous change in c * was observed, and the peak of the Bragg reflection became single again, but remained broad. In the temperature region of T FM > T > T MI , it is considered that the system has a heterogeneous structure, and the coexistence of the high- and low-temperature phases below T FM is presumably related to the anomalous behavior of dielectric constant in the metallic phase. The size of regions/domains was estimated to be about 0.4 µm.

We have studied magnetic field effects on the nonlinear electrical transport associated with a negative resistance and switching phenomena in an antiferromagnetic insulating (AFI) ground state of the title π– d coupled conductor below the metal-to-insulator transition temperature T MI =8.3 K. The overall characteristics of current density ( J ) versus electric field ( E ) are well reproduced by an empirical formula with a current-density-dependent conductivity proportional to J n ; if n >1, a negative resistance effect (d J /d E 0) appears. With increasing magnetic field, there appears a crossover from n >1 to n

We have studied the vortex phase diagram of the organic superconductor κ -(BEDT-TTF) 2 Cu[N(CN) 2 Br], which has layer structure like high temperature superconductors, by means of in- and out-of plane resistivity, ρ ∥ and ρ ⊥ , and DC magnetization measurements as a function of temperature in magnetic fields H perpendicular to the conducting plane. A sharp drop of resistance is observed for the first time at a characteristic temperature T m both in ρ ∥ and ρ ⊥ . Around this temperature, the DC magnetization shows a discontinuous step. These results strongly suggest the existence of the first-order phase transition of vortex system, which can be ascribed to either the vortex lattice melting, or the simultaneous melting and decoupling.

The temperature dependence of the microwave conductivity σ 1 and dielectric constant e 1 has been measured on λ-(BEDT-TSF) 2 FeCl 4 by a cavity perturbation method at 16.3 GHz, employing the TE 011 resonant mode. In spite of the highly metallic state above the metal-to-insulator (MI) transition at T MI = 8.3 K, a novel ferroelectric-like response is observed in e 1 c along c at high temperatures from T MI to T FM = 70 K, which is enhanced to the order of 10 3 just above T MI . Then a transition from a ferroelectric-like to paraelectric-like state with e 1 c ∼ 45 takes part in the MI transition. In contrast to the dc conductivity, σ 1 c becomes much more conductive as considered by a collective mode. The ferroelectric-like response is associated with the dynamical response of the charge degrees of freedom in the π electronic system. An absence of these dielectric and thermodynamical anomalies in the nonmagnetic Ga analogue indicates the importance of the π– d interaction for the ferroelectric-like state as...

To study the magnetic ground state in the title compound of a quasi two-dimensional charge transfer salt containing Fe 3+ ( S = 5/2) paramagnetic ions, we have measured the magnetic torque at 0.4 K ≤ T ≤4 K and H ≤14 T using a capacitive cantilever torque meter. The torque and magnetization data above 1 K are well scaled by the Brillouin plot with a Weiss temperature of -0.8 K. From theoretical analysis for a uniaxial antiferromagnet, anomalous torque curves below 1 K reveal that an antiferromagnetic ordering with its easy axis perpendicular to the conducting a c -plane occurs between 0.5 K and 1 K. This antiferromagnetic order coexists with the metallic state of π-electrons, indicating quite weak π- d interaction.

Single crystals of a new compound Nb5Sn2Ga were obtained by the flux method using molten tin as a solvent. The crystal structure represents a tetragonal symmetry, space group D4h18I4/mcm, ordered W5Si3-type structure. Lattice parameters are a=1.0586(2) nm and c=0.5177(1) nm. According to XPS study, the peaks of Nb, Sn and Ga 3dXP spectra negatively shift when the three elements of Nb, Sn and Ga form the compound of Nb5Sn2Ga. The compound shows superconductivity at Tc=1.75 K and ΔTc=140 mK. The residual resistivity ratio, RRR=ρ (293 K)/ρ (4.2 K), is 12. The Micro-Vickers hardness (MVH) value for the (100) or (110) face is 8.9–8.5 GPa, and for the (001) face is 10.1–9.1 GPa. Oxidation of the Nb5Sn2Ga starts at 562°C. Weight gain of the compound heated up to 1200°C in air is 37.3%. Final oxidation product contains NbO2, Nb2O5, Nb12O29, SnO2 and Ga2O3.

We have studied the complex conductivity in superconducting and normal metallic states of CeRu 2 by the surface impedance measurements at millimeter-wave frequency of 45.4 GHz. The temperature dependence of the complex conductivity below T c = 6.2 K exhibits the characteristic behaviors as seen in a conventional superconductor. The coherence peak observed in the real part σ 1 provides a strong evidence for a conventional s -wave superconductivity as well as the previous NQR measurements. The temperature dependence of the penetration depth evaluated from the surface reactance at low temperatures has revealed the ratio of 2 Δ(0)/ k B T c = 4.4. The strong-coupling theories suggest the electron-phonon coupling strength with λ ep < 2. These results indicate that CeRu 2 is an intermediate strong-coupling superconductor in a clean limit.

Recent developments in the field of π-conjugated polymers have led to considerable improvements in the performance of solution-processed organic light-emitting devices (OLEDs). However, further improving efficiency is still required to compete with other traditional light sources. Here we demonstrate efficient solution-processed multilayer OLEDs using small molecules. On the basis of estimates from a solvent resistance test of small host molecules, we demonstrate that covalent dimerization or trimerization instead of polymerization can afford conventional small host molecules sufficient resistance to alcohols used for processing upper layers. This allows us to construct multilayer OLEDs through subsequent solution-processing steps, achieving record-high power efficiencies of 36, 52 and 34 lm W(-1) at 100 cd m(-2) for solution-processed blue, green and white OLEDs, respectively, with stable electroluminescence spectra under varying current density. We also show that the composition at the resulting interface of solution-processed layers is a critical factor in determining device performance.

We have made a high-resolution photoemission study of quasi-two-dimensional organic conductors BEDT-TTF salts which have various ground states, namely, antiferromagnetic insulator {kappa}-(ET-d{sub 8}){sub 2}Cu[N(CN){sub 2}]Clthinsp, paramagnetic metal {alpha}-(ET){sub 2}KHg(SCN){sub 4}, and superconductors {kappa}-(ET){sub 2}Cu(NCS){sub 2} and {kappa} -(ET){sub 2}Cu[N(CN){sub 2}]Br, where ET denotes BEDT-TTF or bisethylenedithio-tetrathiafulvalene. In all the spectra, the photoemission intensity is suppressed near the Fermi level (E{sub F}), especially for the {kappa}-phase salts, although we have clearly observed a finite E{sub F} intensity for {alpha}-(ET){sub 2}KHg(SCN){sub 4}. Hartree-Fock band-structure calculations for the paramagnetic metallic and antiferromagnetic insulating states qualitatively explain the spectra of {alpha}-(ET){sub 2}KHg(SCN){sub 4} and {kappa}-(ET-d{sub 8}){sub 2}Cu[N(CN){sub 2}]Cl, respectively, while those of {kappa}-(ET){sub 2}Cu(NCS){sub 2} and {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Br strongly deviate from the calculations for the corresponding ground states. These observations imply that, among the metallic compounds, electrons are more strongly correlated in the {kappa}-phase salts than in {alpha}-(ET){sub 2}KHg(SCN){sub 4}. It is shown that long-range electron correlation is quite important to explain the strong deviation of the spectra from the band-structure calculation. The spectra of the {kappa}-phase salts exhibit a remarkable similarity between the metallic (superconducting) and insulating phases across the chemical pressure-induced phase transition. We have also observed unusual temperature dependence ofmore » the spectra for {kappa}-(ET){sub 2}Cu(NCS){sub 2}, {alpha}-(ET){sub 2}KHg(SCN){sub 4}, and {kappa}-(ET-d{sub 8}){sub 2}Cu[N(CN){sub 2}]Cl. {copyright} {ital 1997} {ital The American Physical Society}« less

Magnetic torque of the single crystal of a layered superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br has been measured as a function of field direction with respect to the b-axis under several magnetic fields H up to 8 kOe in the temperature range from 1.5 to 20 K. Smaller value of the anisotropy parameter γ = 180 is obtained for Cu[N(CN)2]Br salt than our previous report γ = 350 for κ-(BEDT-TTF)2Cu(NCS)2. The irreversible region in H — T phase diagram for Cu[N(CN)2]Br salt with smaller γ is larger than that for Cu(NCS)2 salt. A sharp cusp due to the intrinsic pinning is found near H∥ac-plane as in the case of our previous report on other layered superconductors.

We report on the Hall effect measurements of the quasi two-dimensional organic superconductor κ-(BEDT-TTF) 2 Cu(NCS) 2 . A sign reversal phenomenon of the Hall resistivity is found in the mixed state. The Hall conductivity changes monotonically with field and temperature in contrast to the peak structure observed in the Hall resistivity. In low fields, the Hall conductivity diverges to infinity as −1/(H-H ∗ ) , where H ∗ is characteristic field in which the resistivity becomes zero. The phase diagram is proposed from these results.

We have synthesized a new organic conductor α-(BEDT-TTF) 2 KHg(SeCN) 4 which is found to be isostructural with a family of α-(BEDT-TTF) 2 MHg(SCN) 4 with M=K, Tl, Rb and NH 4 , where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene. In contrast to superconducting (M=NH 4 ) or antiferromagnetic (M=K, Tl, Rb) salts, the title compound remains a normal metal in the same way as α-(BEDT-TTF) 2 TlHg(SeCN) 4 . The magnetoresistance and the Shubnikov-de Haas (SdH) effect have been measured at temperatures down to 0.5K and magnetic fields up to 23T. The SdH frequency of 670T, the effective mass of 2.0 m 0 , and the Dingle temperature of 1.6K are obtained in fields perpendicular to the conductive a - c plane. The magnetic field direction dependence of the frequency shows that the observed Fermi surface has a cylindrical shape. The temperature and the field dependence of the SdH oscillation amplitude are well explained by the standard Lifshitz-Kosevich formulation, indicating that the effective mass is essentially ...

Single crystals of Bi-based oxide superconductors including Pb were successfully obtained by the flux method using KCl as a flux. Nitrates of Bi, Pb, Sr, Ca and Cu were used as raw materials. Carefully prepared solute calcined at a low temperature (500 °C) was used with a KCl flux. The solvation of this solute to the KCl flux proceeded very smoothly. Platy single crystals of Bi 1.8 Pb 0.4 Sr 1.6 Ca 1.2 Cu 2 O y having a smooth surface and good crystallinity were extracted near the melt surface, and bulky crystals of Bi 1.8 Pb 0.5 Sr 1.5 Ca 1.2 Cu 2 O y were solidified at the bottom of the crucible. Basically, these as-grown crystals belong to so-called 2:2:1:2 phase, (Bi, Pb) 2 Sr 2 CaCu 2 O y , and show superconducting transitions at 83.5 K and 88 K for platy and bulky crystals respectively.

For an organic π–d metal λ-(BEDT-TSF) 2 FeCl 4 , where BEDT-TSF is an abbreviation of bis(ethylenedithio)tetraselenafulvalene, we have measured 1 H-NMR to clarify the quite anomalous ferroelectric-...

We present optical conductivity studies of the type-I clathrate Ba_8Ga_ Sn_ , using a terahertz time-domain spectrometer (0.3-3.0 THz). The lowest-lying spectral peak at 0.72 THz due to the Ba(2) ion's off-center vibration in the oversized cage shows a drastic and anomalous temperature dependence. Below about 100 K, the single broad peak splits into two subpeaks, and with further lowering of the temperature, the spectral shape of this so-called rattling phonon shows non-Boltzmann broadening to the point that the linewidth becomes comparable to the peak frequency. Whereas the initial splitting can be understood by assuming a multiwell anharmonic potential, the strong linewidth broadening toward low temperature cannot, since the Boltzmann factor generally sharpens the low-temperature spectra. The observed behavior suggests strong interaction between the local anharmonic phonons and other excitations.

Hall-effect measurements below 20 K and up to 23 T on single crystals of the organic conductor α-(BEDT-TTF) 2 KHg(SCN) 4 are reported. The sign of the Hall coefficient R H is positive in the whole temperature range, indicating a hole carrier. R H obtained from the H-linear dependence of the Hall resistance R xy steeply increases below 10 K and saturates around 4 K. This increase in R H coincides with anomalies observed in the static magnetic susceptibility and the electrical resistance at about 10 K

By the measurements of microwave conductivity, terahertz transmission and infrared spectroscopy, we clarify that the two-dimensionally confined water forms hexamer cluster in the MnO 2 interlayer of Na-birnessite, and the hydration states around PO 2 − depend on the type of metallic ions of M-DNA.

A new ternary intermetallic compound Nb6Sn1.5Ge1.5 has been synthesized by the self-flux method using molten tin as a solvent. Well- developed facets of the crystal are [110] planes. The crystal structure is tetragonal (space group D 4h 18 I4mcm : this ternary compound basically has a W5Si3-type structure. The lattice parameters are a = 10.45 (0) A and c = 5.192(0) A , V = 566.97(9) A 3 , Z = 4, and the X-ray density Dx is 8.80 g cm−3 at room remperature. This compound does not show superconductivity down to 1.4 K.

Recently there has been paid much attention to phenomena caused by local anharmonic vibrations of the guest ions encapsulated in polyhedral cages of materials such as pyrochlore oxides, filled skutterdites and clathrates. We theoretically investigate the optical conductivity solely due to these so-called rattling phonons in a one-dimensional anharmonic potential model. The dipole interaction of the guest ions with electric fields induces excitations expressed as transitions among vibrational states with non-equally spaced energies, resulting in a natural line broadening and a shift of the peak frequency as anharmonic effects. In the case of a single well potential, a softening of the peak frequency and an asymmetric narrowing of the line width with decreasing temperature are understood as a shift of the spectral weight to lower level transitions. On the other hand, the case of a double minima potential leads to a multi-splitting of a spectral peak in the conductivity spectrum with decreasing temperature., 8 pages, 11 figures, accepted for publication in Phys. Rev. B

The temperature dependence of the lattice parameters of the title compound has been determined by low-temperature X-ray diffraction measurements down to 20 K. It is found that the parameter a takes a minimum around 150 K and a maximum at 80-90 K, while other parameters of b and c , and the unit cell volume abc almost monotonically decrease with decreasing temperature. This anomalous change in the in-plane parameter a contrasts that in the interlayer spacing observed in κ-(BEDT-TTF) 2 Cu(NCS) 2 , but both structural anomalies correlate phenomenologically with the puzzling resistance maximum around 100 K observed to be common to these organic, high- T c superconductors.

The temperature dependence of the static spin susceptibility ξ spin and the lattice parameters has been measured for a single crystal of the superconductor mentioned in the title. No magnetic anisotropy is found in ξ spin ( T ), excluding the possibility of any magnetic ordering. The ξ spin is almost constant down to 100 K, below which it starts to decrease, accompanied with a 20% reduction. The interlayer spacing d 100 takes a maximum around 100 K, which could be reduced to the change in the hydrogen-bonding distance between the terminal ethylene and the counter anion molecule -SCN-Cu-NCS-. Based on these anomalies with resistance maximum around 100 K, the valence mixing states of Cu 1+ and Cu 2+ ions at high temperatures are postulated.

From low-temperature X-ray diffraction measurements, the interlayer spacing d 100 of the layered organic superconductor κ-(BEDT-TTF) 2 Cu(NCS) 2 is revealed to take a maximum around 100 K. Since d 100 = a ·sin β ( a is the monoclinic lattice parameter and β the angle between the a - and c -axes), this anomalous maximum is due to the combined effect of the monotonous increasing a and decreasing sin β (β>90°) with decreasing temperatures. This result can be attributed to the structural changes in the hydrogen bonding between the terminal ethylene CH 2 and the counter anion molecule -SCN-Cu-NCS-.

The temperature dependence of the electrical conductivity and the low-temperature magnetoresistance for iodine-doped highly conducting polyacetylenes are reported. The overall behavior of the temperature dependence is explained in terms of the phenomenological Sheng model, but the selection of parameter values is not unique, suggesting that the model is not sufficient to characterize the samples. The temperature dependence changes rather drastically with the conductivity, which is determined by the doping concentration and chemical reactions within (CH${)}_{\mathit{x}}$. The magnetic-field effect is rather insensitive to the field direction. This indicates that the classical orbital effect is not the principal cause. The magnetoresistance is negative for the sample with the highest conductivity, and its magnitude exceeds by far the upper bound arising from the quantum correction based on weak-localization theory for isotropic media. We evaluate the effect of the anisotropy in the electron diffusivity on the magnitude. With a decrease in conductivity, positive magnetoresistance emerges at low magnetic fields. The drastic variations of the temperature and the magnetic-field dependence with the conductivity show that the highly conducting polyacetylene is close to the metal-nonmetal transition boundary.

The temperature dependence of the electrical conductivity of the newly developed highly conducting polyacetylene, down to 60 mK, and its high field magnetoconductance up to 15 T are presented. The observed positive magnetoconductance for the most conducting sample exceeds by far the value based on the weak localization theory. The low temperature transport properties vary drastically with small change in the room-temperature conductivity, suggesting that the metallic conduction is realized in the scheme close to metal-nonmetal boundary.

For the title compound of a superconducting organic salt, we have observed twinning and found the twin plane to be (\bar3, 0, 7) by X-ray diffraction method at room temperature. The reduction of the diffuse intensities in the twinned crystal leads that the twin plays a role to decrease the internal strain and also acts as a cleavage plane. It is roughly estimated by the Bijvoet measurement that the twinned region takes a mirror image to the matrix.

Three new Pt complex oxides have been identified as products of the CuO-flux growth of R-Ba-Cu-O superconducting oxides in platinum crucibles. A growth mechanism for the three Pt compounds involving incorporation of Pt from the crucible is proposed. The crystal structure of R2Ba2CuPtO8 has been determined and its relationships to physical properties are discussed.

A systematic study of Va-Sn-Ga (Va = Ta, Nb, V) ternary systems has been made from the point of view of crystal growth, crystal structure and physical properties. Applying the self-component flux method where molten tin acted as a solvent, single crystals of new ternary intermetallic compounds Ta5SnGa2, Nb5Sn2Ga and V5Sn5Ga3, were successfully synthesized. The crystal structures of Ta5SnGa2 and Nb5Sn2Ga are very similar each other: both of them belong to the tetragonal system (space group: 14/mcm) and are isostructural with W5Si3. In contrast to them, V5Sn5Ga3, is orthorhombic (space group: Acam) and crystallizes in a new structural type. Superconducting transitions have been observed in Ta5SnGa2 and Nb5Sn2Ga crystals at 1.80 and 1.75 K.

We report a pronounced peak effect in the magnetization and the magnetocaloric coefficient in a single crystal of the superconductor ${\mathrm{Nb}}_{3}\mathrm{Sn}$. As the origin of the magnetization peak effect in classical type-II superconductors is still strongly debated, we performed an investigation of its underlying thermodynamics. Calorimetric experiments performed during field sweeps at constant temperatures reveal that the sharp increase in the current density occurs concurrently with additional degrees of freedom in the specific heat due to thermal fluctuations and a liquid vortex phase. No latent heat due to a direct first-order melting of a Bragg glass phase into the liquid phase is found, which we take as evidence for an intermediate glass phase with enhanced flux pinning. The Bragg glass phase can, however, be restored by a small ac field. In this case, a first-order vortex melting transition with a clear hysteresis is found. In the absence of an ac field, the intermediate glass phase is located within the field range of this hysteresis. This indicates that the peak effect is associated with the metastability of an underlying first-order vortex melting transition.

A new microporous polyborate, NaCuB7O12.nH2O, is synthesized using boric acid as a flux. It contains a 14-membered ring framework built up by CuO6 octahedra, BO4 tetrahedra and BO3 triangles. The spin-1/2 dimers of Cu2+ ions are connected by BO3 to form an infinite ladder along the b-axis. Magnetic susceptibility data between 2 and 330 K are presented, and the data are accurately fitted by theoretical predictions of Bleaney-Bowers for the spin-1/2 dimer, with J/kB = -153.8 K, and g = 1.98, where J is the intradimer exchange interaction constant and g is the Landé g factor.

A new nickel polyborate, NiB12O14(OH)10 was synthesized using boric acid as a flux. This material has two-dimensional borate layers with a quasi-square lattice of Ni2+. The Ni2+ ions locate in the plane of the two-dimensional layer, bridged through BnOn+1 chains in the plane and connected with the three-membered ring borate groups out of the plane. The dc and ac magnetic susceptibility, magnetization and specific heat measurements show that this material undergoes a weak ferromagnetic phase transition at Tc = 5.8 K. At T < Tc, a metamagnetic phase transition is observed at about 5 T, associated by a spin-flop, suggesting the ferromagnetic ordering is induced by an antiferromagnetic interaction. A broad maximum in the ac susceptibility at TM = 23–24 K indicates an intermediate short-range ordering.

We present magnetoresistance measurements on the organic conductor α-(BEDT-TTF)2KHg(SCN)4 in constant magnetic fields up to 21 T using the hybrid magnet. The resistance minimum in high fields suggests a possible existence of the new phase boundary in the normal metallic phase. It shows a slight temperature dependence around 10 K. The instability of the possible density wave states caused by the magnetic field is discussed with the presented magnetic phase diagram and the recent theoretical model.

We study the current-voltage (I-V) characteristics in a quasi-two-dimensional, π-d coupled organic conductor λ-(BEDT-TSF) 2 FeCl 4 which undergoes a metal-to-insulator transition associated with an antiferromagnetic ordering at T M I =8.3 K. Drastic nonlinear transport phenomena are observed in the I-V curve, revealing a so-called negative resistance effect at an applied electric field or a current density higher than threshold E T or J T . The overall I-V curves are quite well explained phenomenologically by a nonlinear equation for a positive feedback system that the nonlinear conductivity proportional to J n with n = 1.4(′0.1). This indicates that some carrier decondensation mechanism works in the present antiferromagnetic insulator. Discussions are presented by following quite similar nonlinear phenomena observed in a variety of quasi-one-dimensional, mixed-stack, and segregated-stack, organic insulators.

Single crystals of rare earth aluminates REA10 3 (RE  Ce, Pr and Tb) were obtained by a solution growth method. The solute was prepared by a sintering method in a graphite crucible and the crystal growth was performed using KF or PbF 2 as a flux. All processes were carried out under an He atmosphere in order to control the RE valency to RE 3+ . Tetragonal-type single crystals of CeAlO 3 , which are large enough for studies of crystal structures and physical properties, were successfully obtained. The Laue symmetry P4/ mmm was confirmed by means of single-crystal X-ray diffraction using a precession camera and a diffractometer. The lattice parameters are a = 3.7669(9) A and c = 3.7967(7) A. The temperature dependence of the magnetization basically indicates the paramagnetic state. REA1O 3 with RE  Pr and Tb were studied by X-ray powder diffraction and found to belong to the rhombohedral system.

The authors have carried out a concept design and basic fabrication of a novel micro generator system that is applied to micro-electromechanical systems (MEMS) technology. It works in the temperature range from 0 °C to 100 °C. By the theory of Carnot cycle, the efficiency is expected to exceed 10 %.

Intercalation compounds of TiNCl with n-alkyl monoamines (CnH2n+1NH2, 3 ≤ n ≤ 12) and alkylene diamines (H2NCnH2nNH2, 2 ≤ n ≤ 12) have been prepared. Upon intercalation of monoamines, the basal spacing of TiNCl expanded from 7.8 A to a value in the range of 12.0 to 37 A, with the alkyl chains oriented in various ways; the stacking of TiNCl layers became turbostratic disordered. Diamines show only a limited expansion of the basal spacing in a range of 11.1 to 12.3 A with the alkylene chains oriented parallel to TiNCl layers which are mutually shifted along the a- and b-axes in the ab plane, and stacked to form new polytypes with the space group Bmmb or Immm different from Pmmn of the pristine TiNCl. Only diamine intercalated compounds showed superconductivity with the transition temperatures (Tc's) ranging from 6.8 to 17.1 K. The intercalation compounds with diamine molecules with longer alkylene chains tend to exhibit higher Tc's; the compounds with diamines with an even number of carbon atoms tend to have larger superconducting volume fractions. Superconductivities of the intercalation compounds with N,N′-substituted alkylene diamines have been examined, which also showed superconductivity with Tc's in the range of 8.6–15.8 K. It is likely that the charge transfer of the lone pair electrons of amino groups may change the semiconductor TiNCl to superconductors with ordered stacking structures.

We report on 1 H -NMR measurements of an organic π–d metal κ-(BEDT-TSF)2FeCl4, where BEDT-TSF is bis(ethylenedithio)tetraselenafulvalene, C10S4Se4H8. The protons exclusively located at the terminal ethylene are expected to be sensitive to the internal magnetic fields produced by Fe3+ 3d-spins. At high temperatures, the single sharp peak is observed in spectra. Very wide tails are observed at both sides of the central peak below 4 K, where spin-lattice relaxation rate T−11 shows the fast and slow components corresponding to the wide tails and central sharp peak.

Two-dimensionally confined water in between the MnO 2 octahedral layers in Na-birnessite has been studied to clarify the physical properties and the structural arrangements. From the analysis employing an inductively coupled plasma (ICP) method and chemical titration, the chemical composition is determined to be Na 0.28 Mn 4+ 0.73 Mn 3+ 0.27 O 2 y H 2 O in our sample. According to the X-ray diffraction (XRD) experiments, the interlayer distance along the c axis is 7.17 A at 293 K in atmosphere, though the distance shrinks to 5.77 A when the sample is kept either at 333 K in atmosphere or at 293 K in vacuum. The weight loss obtained by thermogravimetry exhibits two steps caused by the dehydration in atmosphere. Together with the XRD data, we confirm that there are two contributions of the water in the interlayers; weakly hydrated water and strongly hydrated water. The latter is regarded as a structural water to maintain the layer structure. In the infrared spectra, three novel peaks are found to develop in...

Using a microwave cavity-perturbation method, the temperature dependence of the complex dielectric constant (\(\tilde{\epsilon}=\epsilon_{1}+\mathrm{i}\epsilon_{2}\)) at 16.3 GHz is measured on a dry poly(dA)–poly(dT) DNA sample prepared under three-different relative humidity (RH) of 0, 11 and 93%. For RH=0%, the temperature dependence of both e 1 and e 2 are explained by the rotational motion of water molecules electrostatically bonding to the negatively charged phosphate group in the primary hydration shell. The activation-type behavior in e 2 is discussed with a double-well potential for a process that the electric dipole of the hydrated water is thermally rotated to the adjacent phosphate groups. For RH=11%, e 2 takes a broad maximum at 280 K due to the collective motion of water molecules in the primary hydration shell. While these features qualitatively resemble to those of free water, the absolute values are much small due to an extremely small number of hydrated water molecules. Moreover the conf...

We report X-ray irradiation-induced carrier doping effects on the electrical conductivity in the organic dimer-Mott insulators $\kappa$-(ET)$_{2}$$X$ with $X =$ Cu[N(CN)$_{2}$]Cl and Cu$_{2}$(CN)$_{3}$. For $\kappa$-(ET)$_{2}$Cu[N(CN)$_{2}$]Cl, we have observed a large decrease of the resistivity by 40 % with the irradiation at 300 K and the metal-like temperature dependence down to about 50 K. The irradiation-induced defects expected at the donor molecule sites might cause a local imbalance of the charge transfer in the crystal. Such molecular defects result in the effective doping of carriers into the half-filled dimer-Mott insulators., Comment: 4 pages, 3 figures