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We have performed soft X-ray angle-resolved photoemission spectroscopy (SXARPES) of a heavily boron-doped superconducting diamond film (Tc=7.2 K) in order to study the electronic structure near the Fermi level (EF). Careful determination of measured momentum space that across Γ point in the Brillouin zone (BZ) and increase of an energy resolution provide further spectroscopic evidence that EF is located at the highly dispersive diamond-like bands, indicating that holes at the top of the diamond-like valence band play an essential role for the conducting properties of the heavily boron-doped superconducting diamond for this boron-doping region (effective carrier concentration of 1.6%). The SXARPES intensities at EF were also mapped out over BZ to obtain experimental Fermi surface sheets and compared with calculations.

An accidental explosion occurred in a waste storage tank at an incineration plant in Kawasaki, Japan, on May 11, 1997. The accident was caused primarily by unintended mixing involving reactive chemicals, such as organic peroxides (POs) and acrylonitrile (AN). The PO initiated polymerization of AN and the heat released during the polymerization led to a runaway reaction and explosion. POs are widely used in the chemical industry and can be self-reactive and hazardous when mixed with other chemicals such as acids and alkalis. The goal of this study was to obtain a better understanding of the mixing hazard of chemicals through an evaluation of POs with other chemicals using conventional experimental techniques such as glass test-tube tests, Dewar vessel tests, and differential scanning calorimetry (DSC). Seven types of POs were mixed with AN. Test results were classified into four ranks based on the hazard criteria. In addition, di(2-ethylhexyl)-peroxydicarbonate/AN mixtures were investigated in detail and the influences of the mixing ratio and the stirring rate were examined.

Organic peroxides (POs) have been widely used in chemical industries as initiators of polymerization, hardening or bridge formation agents, and they are known for its self-reactive and also mixing hazard characteristics when mixed with other chemicals such as acids and alkalis. It is the purpose of this investigation to propose a simple but useful evaluation flow of mixing hazards of POs with other chemicals using conventional experimental techniques such as a glass test tube test, Dewar vessel test and DSC is proposed. 7 kinds of POs (DEPD, THP, TBEH, TBTC, MEKPO, DTBP, THHP) were mixed with sulfuric acids with various concentration, sodium hydroxide solutions, α-iron(III) oxide and acrylonitrile (AN). Based on the proposed evaluation flow the testing results were classified into 4 ranks due to the hazard criteria. Futhermore DEPD/acrylonitrile mixtures were investigated in more detail and the influences of the mixing ratio and the stirring speed were discussed.

X-ray absorption (XAS) and emission (XES) spectroscopy near O K edge has been performed on edge-shared CuO chain compounds Ca2+xY2−xCu5O10 ( 0.0 ≤ x ≤ 2.0 ) using poly- and single-crystalline samples. Two large peaks are observed at 528 eV (PH) and 530 eV (PU) in the XAS spectra. The intensity of the PH peak monotonically increases and that of the PU monotonically decreases with hole doping. The two characteristic peaks in the XAS spectra at PH and PU, which are assigned for the polycrystalline samples to the hole and upper Hubbard band (UHB) states, respectively. The theoretical calculations reproduce the experimental XAS results, especially that the PU peak decreases by hole doping. The spectral weight transfer from the PU peak to the PH peak of the edge-shared chain by hole doping is strongly suppressed in comparison with that of the CuO2 plane. From the single crystal measurements of undoped Ca2Y2Cu5O10, the spectra of XAS and XES are interpreted in terms of a square-like CuO4 plaquette for the compound. As for the hole-doped Ca3YCu5O10 sample, the plaquette containing a doped hole is found to be square-like, and the plaquettes with no doped holes are found to be rectangle-like. We concluded that the doped hole is localized associated with the lattice deformation. The electric properties are discussed based on our result.

Properties of oxide layers at the interface between Al metal and YBa 2 Cu 3 O 7− δ ceramics were investigated using X-ray diffraction (XRD), X-ray photoelectron spectra (XPS) and impedance measurements. There have been found the oriented grains having their c -plane parallel to the surface of YBa 2 Cu 3 O 7− δ . When Al metal was evaporated onto the ceramics sample, the aluminum oxide layer was produced at the interface between Al and YBa 2 Cu 3 O 7− δ because Al metal oxidizes more easily. The oxygen-deficiency was observed at the ceramics side of the interface as examined by X-ray photoelectron spectra. This oxygen-deficiency can be partly replenished by post annealing whereas it can be fully replenished for the sample to which the mechanical polishing is applied beforehand in order to remove the oriented grains. The thickness of aluminum oxide layer was evaluated by means of the impedance measurements using the alternating current three-terminal method.

We compare the angle-resolved photoemission spectra of the hole-doped Cu-O chains in ${\mathrm{PrBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}$ (Pr123) and in ${\mathrm{PrBa}}_{2}{\mathrm{Cu}}_{4}{\mathrm{O}}_{8}$ (Pr124). While, in Pr123, a dispersive feature from the chain takes a band maximum at ${k}_{b}$ (momentum along the chain) $\ensuremath{\sim}\ensuremath{\pi}/4$ and loses its spectral weight around the Fermi level, it reaches the Fermi level at ${k}_{b}\ensuremath{\sim}\ensuremath{\pi}/4$ in Pr124. Although the chains in Pr123 and Pr124 are approximately 1/4 filled, they show contrasting behaviors: While the chains in Pr123 have an instability to charge ordering, those in Pr124 avoid it and show an interesting spectral feature of a metallic coupled-chain system.

Resonant photoemission performed at the SRS Daresbury Laboratory is used to investigate the temperature- and doping-dependent spin states in single crystal LaCoO3(111) and La0.9Sr0.1CoO3(111). In an initial study, the surface reactivity of the LaCoO3(111) surface is investigated using H2O as a probe molecule. The results are used to interpret changes which may occur in the spectra as a function of time and temperature in UHV, due to surface reactions. This allows us to distinguish effects on the valence band spectra due to spin changes as a function of temperature. The temperature dependence of low binding energy features primarily associated with Co in the low spin (LS) state in LaCoO3 is investigated in detail. In particular, the intensity and onset energy of the Co 3p→3d resonance associated with these features is measured at small binding energy intervals. Delayed resonance onset associated with the LS state is consistently observed. This is used to locate the separate contributions of the low spin and higher spin states to the low binding energy spectrum. We find the contribution due to the LS state lies around 1 eV to lower binding energy than that due to higher spin states in LaCoO3. In contrast, we find the spectrum of La0.9Sr0.1CoO3(111) to be invariant with temperature, with no delayed resonance effect. The data are discussed in the light of recent models for the spin transitions, including the two stage spin-state model involving an intermediate spin state. Simulation of the temperature variation of the valence band spectra of LaCoO3 using this model provides good agreement with experiment.

We have performed copper nuclear quadrupole resonance experiments in high-temperature superconductors ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{4}{\mathrm{O}}_{8},$ ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7},$ and ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$ $(x=0.12$ and $x=0.15),$ using the stimulated echo technique which utilizes the rf-pulse sequence $\ensuremath{\pi}/2\ensuremath{-}(\ensuremath{\tau})\ensuremath{-}\ensuremath{\pi}/2\ensuremath{-}(T\ensuremath{-}\ensuremath{\tau})\ensuremath{-}\ensuremath{\pi}/2.$ The $\ensuremath{\tau}$ and T dependences of the stimulated echo intensity is analyzed by a model that includes the spin-lattice relaxation process ${(T}_{1}$ process) and the fluctuating local field due to nuclear spin-spin coupling. The model gives quantitative account of the experimental results in ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{4}{\mathrm{O}}_{8}$ and ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7},$ using the known values of ${1/T}_{1}$ and ${1/T}_{2G},$ the Gaussian decay rate of the spin-echo intensity. The same model applied to ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$ enables us to extract the value of ${T}_{2G}.$ Our results indicate that ${T}_{1}{T/T}_{2G}^{z}$ shows significant temperature dependence for $z=2$ but is approximately independent of temperature for $z=1.$ This implies that the dynamic exponent is close to one in ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}.$

Both (Y1−xPrx)Ba2Cu4O8 (hereafter abbreviated as Y/Pr124) and (Y1−xPrx)2Ba4Cu7O15−y (Y/Pr247) compounds were successfully synthesized over the whole concentration range 0≤x≤1 by means of either hot isostatic pressing (HIP) technique or high pressure oxygen gas technique. We revealed that the superconducting transition temperature disappears at xc=0.8 in both systems in contrast to xc=0.5 for the (Y1−xPrx)Ba2Cu3O7 (Y/Pr123) system reported in the literature and concluded from this that the suppression of superconductivity due to the Pr-doping is weaker in both 124 and 247 systems than that in the 123 system. Furthermore, a combination of the magnetic susceptibility data in the normal state with the Pr–O distance derived from the neutron diffraction experiments led us to conclude that the Pr ion is in the trivalent state for all samples in both 124 and 247 systems. An increase in the critical concentration xc in the Y/Pr124 and Y/Pr247 systems relative to that for the Y/Pr123 system is attributed to an increase in the hybridization of the Pr-4f and O-2p orbitals.

Electric field gradients at 117 In(← 117 Cd) nuclei in BaRu 2/3 (M 0.97 116 Cd 0.03 ) 1/3 O 3 (M=Ca, Cd, and Sr) were measured in the temperature range between 4 and 773 K by time-differential perturbed-angular-correlation of the 90-345 keV cascade γ -rays. For each oxide, the quadrupole interaction frequency markedly increases below a specific temperature; the temperatures are between 4 and 77 K for M=Ca, and about 300 and 600 K for M=Cd and Sr, respectively. Combined with the results of the X-ray powder diffraction measurements, it is concluded that a hexagonal-monoclinic structural phase transition, associated with a deformation of MO 6 octahedra, takes place at the temperature.

Directional magnetic Compton profiles (MCPs) of ferromagnetic intermetallic compound Mn 1.1 Sb are measured using a circularly polarized synchrotron radiation light source. The overall shape of the derived momentum-density distribution of the magnetic electrons is reproduced well with the Hartree-Fock 3 d wavefunction of free Mn atoms except in the low momentum region (∣ P ∣2.0 atomic units). The anisotropy observed in the low momentum region is inexplicable only with the population, determined previously by a polarized neutron measurement, of unpaired electrons in Mn-3 d orbitals in the trigonal crystalline field. The present result suggests an additional anisotropic negative polarization of Sb-5 p electrons. The anisotropy is discussed using the hydrogen-like atomic Sb-5 p wavefunctions.

We have investigated the effects of pressure on the electrical resistivities of PrBa 2 Cu 4 O 8 (Pr124) and Pr 2 Ba 4 Cu 7 O 15−δ (Pr247). The temperature coefficient of the resistivity is positive below 150–190 K ( T m ) while that above T m is negative for both systems. We found that the resistivity below T m is insensitive to pressure in the pressure range 0–1 GPa and by contrast the resistivity above T m remarkably increases with increasing pressure. At higher pressures the resistivity below T m is also affected by pressure. We attribute the positive temperature coefficient of the resistivity below T m to the metallic conduction along the double chains and the negative one above T m to the semiconducting conduction through the CuO 2 planes.

The PrBa 2 Cu 4 O 8 compound with a trace of BaCuO 3 and PrBaO 3 was synthesized for the first time by annealing at the temperature or 957°C under 5 atm oxygen pressure. The content of the PrBaO 3 is estimated to be less than 0.2%. The superconducting transition was not detected down to 2 K. The magnitude of the resistivity and its temperature dependence are consistent with the possession of a metallic character in this compound in contrast to the semiconducting behavior reported previously for the PrBa 2 Cu 3 O 7- δ compound. The effective magnetic moment, μ eff , estimated from the Curie-Weiss fitting to the magnetic susceptibility data, turns out to be 2.67 μ B .

(Y 1- x Pr x )Ba 2 Cu 4 O 8 compounds with x =0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7 were synthesized using a high-pressure oxygen technique. The solubility limit x s in this compound system was found to be 0.7. In this composition range, (Y 1- x Pr x )Ba 2 Cu 4 O 8 compounds have the YBa 2 Cu 4 O 8 (124) structure and the lattice parameters a , b and c increase with increasing Pr content x . The superconducting transition temperature T c decreases monotonically with increasing x , and the critical content x c , where superconductivity disappears, has been estimated to be 0.8. There is an obvious effect of Pr substitution on superconductivity, although the effect is smaller in the 124 system than that in the 123 system. X-ray diffraction results suggest that Pr is almost 3+ in this system. A model for the Pr substitution is suggested to make holes immobile to suppress superconductivity as the result of the hybridization of O 2p π with Pr 4f orbitals.

121Sb Mossbauer spectra for ferromagnets, Mn1+x Sb (0.00≤x≤0.22) in e phase were measured at 77 K. The large unique hyperfine magnetic field (H hf=361 kOc) atx=0 tends to decrease and to have a wide distribution with increase ofx. The decreasing ratio of the mean value ofH hf for the nonstoichiometric samples is in accordance with that of their magnetizationM S(x), i.c., the relation\(\overline {H_{hf} } (x)/H_{hf} (0) = M_S (x)/M_S (0)\) holds in this system.

Magnetic properties of four intermetallic compounds, e, e 1 , κ and η, in manganese-germanium system are studied by means of magnetization measurement and neutron diffraction. Exchange coefficients of the interaction between Mn atoms in the compounds are estimated quantitatively using the molecular field approximation, based on the localized moment model. The exchange coefficient between Mn atoms on different sublattices is found to depend largely on the interatomic distance: The exchange coefficient is found to be negative for smaller interatomic distances than r c =2.9 A and positive for larger distances. The magnitude of atomic magnetic moment in the compounds is consistently discussed using the Pauling valence, after Mori and Mitsui (J. Phys. Soc. Jpn. 25 (1968) 82).

X-ray absorption (XAS) and emission (XES) spectroscopy near B K and C K edges have been performed on metallic ($\ensuremath{\sim}0.1\phantom{\rule{0.3em}{0ex}}\mathrm{at.}\phantom{\rule{0.2em}{0ex}}%$ B, B-diamond) and semiconducting ($\ensuremath{\sim}0.03\phantom{\rule{0.3em}{0ex}}\mathrm{at.}\phantom{\rule{0.2em}{0ex}}%$ B and N, BN-diamond) doped diamond films. Both B K XAS and XES spectra show a metallic partial density of states (PDOS) with the Fermi energy of $185.3\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$, and there is no apparent boron-concentration dependence in contrast to the different electric property. In C K XAS spectrum of B-diamond, the impurity state ascribed to boron is clearly observed near the Fermi level. The Fermi energy is found to be almost same with the top of the valence band of nondoped diamond: ${E}_{V}=283.9\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. C K XAS of BN-diamond shows both the B-induced shallow level and N-induced deep and broad levels as the in-gap states, in which the shallow level is in good agreement with the activation energy $({E}_{a}=0.37\phantom{\rule{0.3em}{0ex}}\mathrm{eV})$ estimated from the temperature dependence of the conductivity; namely, the change in $\mathrm{C}\phantom{\rule{0.2em}{0ex}}2p$ PDOS of impurity-induced metallization is directly observed. The electric property of this diamond is ascribed mainly to the electronic structure of $\mathrm{C}\phantom{\rule{0.2em}{0ex}}2p$ near the Fermi level. The observed XES spectra are compared with the discrete variational $\mathrm{X}\ensuremath{\alpha}$ ($\mathrm{DVX}\ensuremath{\alpha}$) cluster calculation. The $\mathrm{DVX}\ensuremath{\alpha}$ result supports the strong hybridization between $\mathrm{B}\phantom{\rule{0.2em}{0ex}}2p$ and $\mathrm{C}\phantom{\rule{0.2em}{0ex}}2p$ observed in XAS and XES spectra, and suggests that the small amount of boron $(\ensuremath{\leqslant}0.1\phantom{\rule{0.3em}{0ex}}\mathrm{at.}\phantom{\rule{0.2em}{0ex}}%)$ in diamond occupies the substitutional site rather than interstitial site.

The effect of electron correlation (EC) on the electronic structure in MgB 2 , AlB 2 , and ZrB 2 , is studied by examining the partial density of states (PDOS) of B 2pσ and pπ orbitals using the polarization dependence of x-ray emission and absorption spectra. The discrepancies between observed and calculated PDOS's cannot be attributed to EC effects. The present results suggest that the EC effect is less than the experimental error (∼0.2 eV), which indirectly supports a scenario that electron-phonon interaction plays an essential role in the occurrence of superconductivity.

Results of the nuclear resonance experiments for the planar Cu sites in PrBa 2 Cu 4 O 8 are presented. The nuclear magnetic resonance spectrum at 1.5 K in zero magnetic field revealed an internal field of 6.1 T, providing evidence for an antiferromagnetic order of the planar Cu spins. This confirms that the CuO 2 planes are insulating; therefore, the metallic conduction in this material is entirely due to the one-dimensional zigzag Cu 2 O 2 chains. The results of the spin-lattice relaxation rates measured by zero-field nuclear quadrupole resonance above 245 K in the paramagnetic state are explained by the theory for a Heisenberg model on a square lattice.

X-ray emission (XES) and absorption (XAS) spectra near the B-$K$ edge were measured on single-crystalline AlB$_2$ compound which is an isostructural diboride of superconducting MgB$_2$. The partial density of states (PDOS) of B-2$p\sigma$ and $p\pi$ orbitals were derived from the polarization dependence of XES and XAS spectra. There are considerable amounts of PDOS near the Fermi energy in AlB$_2$ similarly to that in MgB$_2$, but there are almost no PDOS in $p\sigma$ orbitals of AlB$_2$ near the Fermi energy, i.e., a pseudo-gap in $p\sigma$ state and a broad metallic state in $p\pi$ state are observed. The present result indirectly supports scenarios that the $p\sigma$ holes play an important role in the occurrence of superconductivity in MgB$_2$. The overall features of PDOS were found to be in good agreement with the result of band calculation of AlB$_2$, but a small discrepancy in the Fermi energy is observed, which is attributed to the Al vacancy in the compounds, i.e., the estimated concentration is Al$_{0.93}$B$_2$., Comment: LaTeX files and 4 eps figures, to be published in J. Phys. Soc. Jpn

Soft X-ray absorption and emission measurements are performed for the K- edge of B in MB$_2$ (M=Mg, Al, Ta and Nb). Unique feature of MgB$_2$ with a high density of B 2$p_{xy}(\sigma)$-state below and above the Fermi edge, which extends to 1 eV above the edge, is confirmed. In contrast, the B 2$p$ density of states in AlB$_2$ and TaB$_2$, both of occupied and unoccupied states, decreased linearly towards the Fermi energy and showed a dip at the Fermi energy. Furthermore, there is a broadening of the peaks with $p\sigma$-character in XES and XAS of AlB$_2$, which is due to the increase of three dimensionality in the $p\sigma$-band in AlB$_2$. The DOS of NbB$_2$ has a dip just below the Fermi energy. The present results indicate that the large DOS of B-2$p\sigma$ states near the Fermi energy are crucial for the superconductivity of MgB$_2$.

We have performed an angle-resolved photoemission study on PrBa2Cu307 (Prl23) and PrBa2Cu408 (Prl24) which have hole-doped Cu-O chains. Dispersive features with one-dimensional (ID) character are observed in Prl23 and Prl24 and are attributed to signals from the hole-doped Cu-O chains which are approximately 1/4-filled. While, in Prl23, the ID feature loses its spectral weight near the Fermi level (EF), it crosses EF in Prl24. These results suggest that, while the hole-doped Cu-O single chains in Prl23 have instability to charge ordering, the hole-doped Cu-O double chains in Prl24 can get rid of it.

The superconducting transition temperature (T c ), magnetic susceptibility and pressure depehdence of T c were measured for (Y1−xPrx)2Ba4Cu7O15−δ (x=0, 0.1, 0.4 and 0.6), all of which were synthesized under high O2 pressure. The degree of depression of T c due to Pr doping in the 247 phase is closer to that found in the Pr-doped 124 phase than that in the Pr-doped 123 phase. A variation of the lattice parameter suggested that doped Pr is in the valence state of 3+, but magnetic susceptibility data indicated a mixed valence state for the Pr ion in the 247 phase. We found that the pressure dependence of T c , dT c /dP, changes its sign gradually from a positive to negative one with increasing Pr concentration. In particular, the value of dT c /dP for the x=0.6 sample reached −18 K/GPa.

The superconducting transition temperature (T c ) was measured as a function of pressure up to 2 GPa for Y2Ba4(Cu1−xCox)7O15−δ (x=0,0.03 and 0.05) which was synthesized under high O2 pressures. The unit cell of 247-compound is built up from the alternative stacking of the 123 and 124 blocks. Thus, single and double chains appear alternatively with each other. The value of T c decreased with increasing Co content x. Irrespective of Co contents, a large enhancement of T c was observed with increasing pressure up to 1 GPa. The T c tends to be saturated in the pressure above 1 GPa. We found from neutron diffraction analysis that the doped Co atoms occupy only the Cu site in the single chain.

Pr 3d and 4d core levels have been studied for ${\mathrm{Y}}_{0.4}$${\mathrm{Pr}}_{0.6}$${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{4}$${\mathrm{O}}_{8}$ and ${\mathrm{PrBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ using x-ray-photoelectron spectroscopy to elucidate the valence states. The features of Pr 3d and 4d are close to those for ${\mathrm{Pr}}_{2}$${\mathrm{O}}_{3}$ for both compounds, while they are different from those for ${\mathrm{Pr}}_{6}$${\mathrm{O}}_{11}$. It is concluded that praseodymium is almost trivalent with a 4${\mathit{f}}^{2}$ configuration.

Carbon- and boron-2 p states of superconducting and non-superconducting boron-doped diamond (BDD) samples are measured using soft X-ray emission and absorption spectroscopy (XES and XAS) near C- and B-K edges. The electronic structure of B 2 p does not show a marked boron-doping dependence, except that a considerable amount of in-gap state in empty states is observed. In C-K XAS spectra, two peaks H and I are observed around the Fermi level. The H peak is attributed to 2 p state of carbon first-nearest neighboring to the dopant boron atoms (1NN-C), and the I peak to 2 p state of carbon further than 1NN-C from an impurity boron. Incoherent (normal-excitation) XES spectra do not show a large chemical shift by B-doping, but its intensity just below the valence band maximum (VBM) decreases with B-doping. It cannot be interpreted within a simple rigid band model. An elastic peak of I -excited C-K XES spectrum and the width of I -peak of C-K XAS spectrum suggest that impurity state is localized in non-supercond...

The polarization dependence of soft x-ray absorption spectroscopy (XAS) and x-ray emission spectroscopy (XES) near the O 1 s absorption edge was measured on two-leg ladder single-crystalline samples of (Sr,Ca,Y,La) 14 Cu 24 O 41 (14-24-41). The hole distributions in 14-24-41 compounds are determined by polarization analysis. For samples with less than or equal to 5 holes/chemical formula (c.f.), all holes reside on the edge-shared chain layer. In the case of Sr 14- x Ca x Cu 24 O 41 (6 holes/c.f.), there is approximately one hole on the two-leg ladder layer, with about five holes remaining on the edge-shared chain layer. By Ca substitution for Sr in the Sr 14- x Ca x Cu 24 O 41 samples, 0.3 holes transfer from the edge-shared chain to the two-leg ladder layer. It is possible that some of the holes on the two-leg ladder layer move from the rung sites to the leg sites upon Ca substitution.

The polarization dependence of x-ray absorption at the oxygen 1 s absorption edge in untwinned LuBa 2 Cu 3 O 7 and PrBa 2 Cu 3 O 7 single crystal specimens was measured. The hole states of oxygen in the CuO 2 plane in PrBa 2 Cu 3 O 7 locate at higher energy position than those of the oxygen in the CuO 2 in superconducting LuBa 2 Cu 3 O 7 , although the hole states of chain sites remain at the same energy position in both Pr123 and Lu123 samples. Although they are mainly of pσ character rather than of pπ and were attributed as an upper Hubbard band, a possibility was pointed out that a trace of pπ character hole states in the CuO 2 plane exists in Pr123. The formation of Zhang-Rice singlet is suppressed by pπ holes in the CuO 2 plane on account of the strong Coulomb interaction on an oxygen site.

PrBa 2 Cu 4 O 8 (Pr124) does not exhibit superconductivity, but its resistivity shows a metallic behavior below 180K. This behavior is in a sharp contrast to the semiconducting one of PrBa 2 Cu 3 O 7−y (Pr123). A substitution of Pr by RE(Rare earth elements) in the Pr123 is known to induce the superconductivity. For example, the critical RE concentration, XTc , corresponding to the onset of superconductivity for RE Y, Yb, Gd and Nd has been reported to be 0.45, 0.35, 0.5 and 0.65, respectively. In thi study, we could prepare stoichiometric (Pr 1−x RE x )Ba2Cu 4 O 8 oxides by using high oxygen pressure technique, and investigated the physical properties. In the case of RE Y, Yb and Gd, the semiconducting region has disappeared and the superconductivity appeared at x=0.3, 0.25 and 0.4, respectively. This result means that Pr-effect in the 124 system is smaller than that in the 123 system.

The effect of Pr on the superconductivity in (Pr x Y 1−x )Ba 2 Cu 4 O 8 were studied and compared with that in (Pr x Y 1−x )Ba 2 Cu 3 O 7 . Transition temperatures of the (Pr x Y 1−x )Ba 2 Cu 4 O 8 compounds decrease with increasing Pr content x, although the rate of decrease is slower than that of (Pr x Y 1−x )Ba 2 Cu 3 O 7 . Thus the Pr has a weaker effect to the superconductivity suppression in (Pr x Y 1−x )Ba 2 Cu 4 O 8 than in (Pr x Y 1−x )Ba 2 Cu 3 O 7 . From the analysis of X-ray absorption spectra(XAS) near O K-edge in (Pr x Y 1−x )Ba 2 Cu 4 O 8 and in (Pr x Y 1−x )Ba 2 Cu 3 O 7 , the effect of Pr substitution on the O 2p electronic state is found to be weaker for (Pr x Y 1−x )Ba 2 Cu 4 O 8 , which is parallel to the effect on superconductivity. These results were well explained with the hole localization model based on the hybridization of Pr 4f and O 2p orbitals.

We have investigated the magnetic susceptibility at atmospheric pressure for the (Y1−xPrx)2Ba4Cu7O15−δ system with x=0.1−0.6 and that at high pressure for the sample with x=06. The effective moment per Pr ion obtained by the Curie-Weiss fitting is an intermediate value between that expected for Pr3+ and that for Pr4+. It was found that the magnetic state of Pr ion is scarcely affected by pressure.

The compounds of (Pr x Y 1−x )Ba 2 Cu 4 O 8 (x=0, 0.1 and 0.6) were prepared in the oxygen atmosphere of 33 atm using a electrical furnace, where the materials were annealed at 930°C for 48 h. Magnetic and electrical measurements were performed: Transition temperatures for compounds of x=0, 0.1 and 0.6 were 80 K, 75 K and 44 K, respectively. The critical content X c , at which superconductivity disappears, was estimated to be 0.9. Effective moment and the Pauli paramagnetic component of Pr 0.6 Y 0.4 Ba 2 Cu 4 O 8 were 3.05±0.15 and (1.3±0.2) x 10 -6 cm 3 /g, respectively.

57 Fe Mossbauer and magnetic measurements of BiPbSr 2 FeO 6 calcinated in air (sample I) or in N 2 gas (sample II) were made. Sample I is a weak-ferromagnet with T N =240 K. The temperature dependence of the magnetization shows an anomaly at 90 K. A large effect of the magnetic field cooling is observed. Fe ions are in trivalent state and 57 Fe nuclei feel a hyperfine magnetic field of 50 T at low temperature. Sample II is a weak ferromagnet with T N =300 K, but neither the anomaly at 90 K nor the field-cooling effect is detected for this sample.

The zero bias anomaly dependent on the preferred surface grain orientation of YBa2Cu3O7-δ ceramics has been investigated in the conductance curve of the tunneling characteristics. A tunnel junction was fabricated by evaporating Al metal onto the ceramics sample and then annealed to remove the oxygen-deficient layer. The preferred orientation and the oxygen deficiency on the surface were examined based on X-ray diffraction patterns and X-ray photoelectron spectra. There exist oriented grains with their c-plane parallel to the ceramics sample surface. These surface layers are oxygen-deficient. Using the junction fabricated on the oxygen-deficient grains, the zero bias anomaly appears on the dynamic conductance curve of the tunneling characteristics. This anomaly disappears when the junction is fabricated after mechanical polishing of the surface and annealed. One of the sources of zero bias anomaly is the existence of oxygen-deficient grains on the YBa2Cu3O7-δ surface.

The recovery of the electrode conductance for Au metal on YBa2Cu3O7-δ (YBCO) has been investigated. The reduction in the electrode resistance, which is defined as the inverse of the electrode conductance, was measured during heat treatment ranging from 150 to 280° C. The reduction has been characterized by two relaxation processes with activation energies of 0.52±0.04 and 1.40±0.03 eV. The former activation energy corresponds to that of the process in which the oxygen-deficient layer at the YBCO surface is replenished by oxygen diffusion from the bulk, and the latter to that of the process of rearrangement of Au atoms at the YBCO/Au interface which results in improved interconnections between Au metal and YBCO.

The results of magnetic and X-ray studies have led to a conclusion that the high-temperature ϵ phase of MnGe system, which has D019 type of structure, has the homogeneity range 22.7–24.0 at.% Ge at 800°C and is metastable below ∼515°C. The Curie temperature, asymptotic Curie temperature, the Curie constant and the effective magnetic moment per Mn of the weak ferromagnetism, which is parasitic on a triangular antiferromagnetism, are 365 K, -853 K, 2.39 × 10−2 K cm3/g and 3.89 μB, respectively, for 23.5 at.% Ge. The study on a single crystal with 23.0 at.% Ge confirmed that the spontaneous magnetization lies within the basal plane, with zero-field magnetic moment of 0.007 μB/Mn and nearly isotropic incremental susceptibility of 2.0 × 10−5cm3/g, in substantial agreement with the theory by Nagamiya et al.

Antiferromagnetic-ferromagnetic transitions were examined on the single crystals of 0 -Mn 11 Ge 8 and ζ 1 -Mn 2.6 Ge. The entropy changes associated with the transitions were calculated to be ΔS/T = 250 erg/gK 2 below 100K for the former compound and ΔS = 1.2 X 10 4 erg/gK at 120 K for the latter.

The magnetic structure of an N-type ferrimagnet κ-Mn 5 Ge 2 has been determined by Rietveld analysis of its powder neutron diffraction data. The magnetic moments on three Mn sites (4 b , 8 f , 8 j ) has been found to be collinear along an orthorhombic b axis, with the respective values µ(4 b )=2.54±0.11 µ B , µ(8 f )=2.26±0.06 µ B . and µ(8 j )=-3.11±0.08 µ B , at 13 K.

Magnetic properties of an orthorhombic intermetallic compound Mn 11 Ge 8 , which was formerly referred to as Mn 3 Ge 2 , has been investigated on a single crystal specimen at temperatures between 80 K and 800 K. The compound has features of a non-collinear antiferromagnet below T t = 150 K, and makes a spin-flopping transition when magnetized along the c axis. It becomes ferromagnetic with a first order transition at T t with the direction of easy magnetization lying along b axis up to its Curie temperature 274 K. The susceptibility follows the Curie-Weiss law above 550 K, with asymptotic Curie temperature 329 K and effective Bohr magneton number per Mn P eff = 3.26.

The authors surveyed the soil evaporation in the urban pine forest by using the neutron soil moisture guage. the surveyed plots were set in three characteristic frest, which was a regenerated or old age pine, and ubame-gashi forest in Yashima. The soil evaporation are affected by the flora transpiration, gravitational, and capillary water in the forest soil. The authors decided it only from a loss of soil moisture for a reason of simplifying the calculations. The obtained results are as follows.1. In the old age pine forest, the holding capacity of the soil moisture was the greatest of three plots. The soil moisture was almost constant in 7th day after a rainfall (29mm). The moisture increment ratio by this rainfall was about 130%. In relation to these results, the authors considered this forest had a good regulation function of soil moisture.2. In ubame-gashi forest, the soil moisture was changed by the same manner as the old age pine forest after a rainfall. However, because of low soil moisture (about 30%) and increment ratio (about 130%), the autoors judged this forest had a bad regulation function.3. In the pine regenerated forest, the soil moisure was not constant in 7th day after a rainfall. The increment ratio by this rainfall was the highest percentages of these plots (about 170%), and this soil had the same low moisture as the udame-gashi forest. From these resutts, the authors supposed the pine species were remarkably regenerate dunder such a good soil condition as this forest, in which the soil water after a rainfall was changed gently.4. Soil evaporation in 9th day-12th day after a rainfall, which was seemed to be unaffected with the gravitational water, indicated the highest value in the old age pine forest (57 ton/ha/day). This value was 25 ton/ha/day in the regenerated pine forest, and 23 ton/ha/day in the ubarne-gashi forest. From these results. the importance of the management and conservation of such an arid urban forest as seto-uchi district were remarkably closed rip.

A calculation is made on the thermomagnetic curves of an N-type ferrimagnet ϰ-Mn 5 Ge 2 , based on the molecular field theory using the magnetic structure determined by the neutron diffraction. The resultant magnetization calculated as a function of temperature reproduces the features of the experimental curve.

Resonant photoemission performed at the SRS Daresbury is used to investigate the temperature- and doping-dependent spin transitions in single crystal samples of the La1-xSrxCoO3 system (x=0, x=0.1). For LaCoO3, the measurements taken over a wide temperature range are interpreted in the light of current models for the spin transitions. The Sr-doped compound is found to be in the same spin state at all temperatures. The temperature dependence of low binding energy features primarily associated with Co in the low spin state is investigated in detail. In particular, the intensity and onset energy of the Co3p→3d resonance associated with these features is measured at small binding energy intervals. This is used to locate the separate contributions of the low spin and higher spin states to these signals. In addition, the surface reactivity of the LaCoO3 (111) surface is investigated using H2O as a probe molecule, and the results are used to interpret changes which may occur in the spectra as a function of time in UHV.

NMR measurements for Co 59 in Co 2 TiAl below and above the Curie point 135 K were carried out. The hyperfine field H hf was found to be +16.6±0.1 kOe at 4.2 K and to decrease with increasing temperature in good agreement with the saturation magnetic moment, i.e. with the magnetic moment of cobalt atom, µ Co . At temperatures above 200 K, the Knight shift K changes linearly with respect to the susceptibility χ with a slope corresponding to +49.2±2 kOe/µ B . This value is in good agreement with the ratio H hf /µ Co in the ferromagnetic region.

From the magnetization measurement on single crystal, two magnetic first-order transitions have been found for ζMn 2.6 ,Ge. The one is at T t1 =120 K and the other at T t2 =310 K in a magnetic field of 10 kOe, both associated with abrupt increase in the magnetization. The easy axis of magnetization is perpendicular to the trigonal symmetry axis in a range of temperature above T t1 , and parallel at temperatures above T t2 . The entropy changes at these transitions have been estimated from the dependence of the transition temperature on magnetic field to be Δ S 1 =6.8{ t i m e s }10 3 erg/K g and Δ S 2 =2.0×10 3 erg/K g.