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We report angle-resolved photoemission spectroscopy results of A-site ordered perovskite CaCu3Ti4O12. We have observed the clear band dispersions, which are shifted to the higher energy by 1.7 eV and show the band narrowing around 2 eV in comparison with the local density approximation calculations. In addition, the high-energy multiplet structures of Cu 3d8 final states have been found around 8-13 eV. These results reveal that CaCu3Ti4O12 is a Mott-type insulator caused by the strong correlation effects of the Cu 3d electrons well hybridized with O 2p states. Unexpectedly, there exists a very small spectral weight at the Fermi level in the insulator phase, indicating the existence of isolated metallic states. [ABSTRACT FROM AUTHOR]

We have performed soft x-ray angle-resolved photoemission spectroscopy (ARPES) for the electron-doped high-temperature superconducting cuprates (HTSCs) Nd2-xCexCuO4 (x = 0.075 and 0.15) in order to disclose their genuine bulk electronic structures. Our soft x-ray ARPES has revealed that the bulk-derived nodal 'kink' (the abrupt change of the electron velocity in quasiparticle dispersions), being absent in the low-energy ARPES, is clearly observable for the electron-doped superconducting Nd1.85Ce0.15CuO4. This result confirms that the antiferromagnetic spin correlation is suppressed and the electron-phonon interactions are prevailing in the bulk of the electrondoped superconducting Nd2-xCexCuO4 at the optimal doping level. The nodal 'kink' behavior is equivalent to that observed in the hole-doped HTSCs. The anisotropic strong electron-phonon interactions seem to be inherent in the HTSCs irrespective of the type of doped carriers. [ABSTRACT FROM AUTHOR]

Abstract: There are various marine algal products consumed as traditional food in the Noto Peninsula area, Japan. Water extract solution (WE) and ethanolic extract solution (EE) were prepared from three brown algae, Phaeophyceae Scytosiphon lomentaria (kayamo-nori, dried product), Papenfussiella kuromo (kuromo, fresh-raw product) and Nemacystus decipiens (mozuku, fresh-raw product), and one Rhodophyceae Porphyra sp. (nori, dried product). We also studied their phenol contents and antioxidant properties including (1) suppression of hemoglobin-induced linoleic acid peroxidation, (2) reducing power, (3) ferrous ion chelating, (4) 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and (5) scavenging of superoxide anion radical-generated non-enzymatic system. WE contained phenolic compounds about 2.2–9.4mg catechin equivalent (CE)/g dry sample and showed strong antioxidant activities, although the results were varied with the five test models. On the other hand, the antioxidant activities of EE were not detected or very low compared to the ones of WE. [Copyright &y& Elsevier]

Abstract: We report on a high-energy angle-resolved photoemission (ARPES) study of the n-type high- cuprate, Nd1.85Ce0.15CuO4 (NCCO). Our bulk sensitive results suggest a hole-like Fermi surface as seen by the so far reported low-energy ARPES studies. The soft X-ray Cu 2p core-level photoemission spectra show clear polar-angle dependence, suggesting the difference in electron states between the bulk and surface. [Copyright &y& Elsevier]

Abstract: We have performed a soft X-ray photoemission (PES) study of quasi-two-dimensional organic conductors BEDT-TTF (ET) and BEDO-TTF (BO) salts. We have clarified the difference in the electronic states between the bulk and surface insulating layers. The difference of the electronic states between ET and BO molecules is also found. On the other hand, the spectral weight in the vicinity of Fermi level is suppressed as reported by the low-energy PES. [Copyright &y& Elsevier]

Abstract: CeRh3B2 is a ferromagnet with exceptionally high Curie temperature ( K) among the Ce compounds with no transition metal magnetic element. Magnetic circular dichroism of soft X-ray photoabsorption (XMCD) has revealed that the orbital angular momentum of Ce 4f electron is quenched to some extent. In addition, preferential occupation of the Ce 4f orbital pointing to the c-axis has been confirmed by the soft X-ray photoabsorption measurements with different geometries. On the other hand, resonant photoemission around the Ce 3d  4f photoabsorption edge has been adopted in order to disentangle the Ce 4f and Rh 4d components in the valence band. The Rh 4d spectrum is qualitatively consistent with the band structure calculation. Although the Ce 4f spectrum has a peak near the Fermi level, the spectral shape is qualitatively different from that of the typical Kondo materials and is rather similar to that of itinerant Ce 4f systems. [Copyright &y& Elsevier]

Abstract: Bioleaching of Sarcheshmeh (Iran) molybdenite concentrate using a native strain of Acidithiobacillus ferrooxidans for extraction of rhenium was evaluated. Bioleaching tests showed that rhenium was extracted from the molybdenite concentrate, but rhenium extraction was low. Maximum rhenium extraction was 7.3%, while molybdenum extraction was 0.54%. The native strain of the Acidithiobacillus ferrooxidans had been able to grow on media that contain up to 250 mg/L molybdenum by the addition of pyrite as an energy source, approximately three times more molybdenum than those that had been reported for Acidithiobacillus ferrooxidans. [Copyright &y& Elsevier]

Ammoniacal thiosulphate leaching of gold finds a better substitute as it is non-toxic and environmentally safe as compared to the toxic cyanide system for gold extraction. In the present study, an attempt is made to assess the feasibility of ammoniacal thiosulphate leaching of gold ore samples from two different mines namely Akeshi and Hishikari of Japan. In this study, the effect of thiosulphate concentration, effect of ammonia, effect of cupric ions, and few other variables affecting the gold leaching have been studied. The ammoniacal thiosulphate leaching of gold is dependant on both ammonia and thiosulphate concentration. The leaching is improved significantly at a particular ratio of ammonia to thiosulphate concentration and that ratio varies from ore to ore. Copper ions act as an oxidant and the gold dissolution increases substantially in the presence of them. The gold leaching is minimum in the presence of an inert gas such as nitrogen and the leaching increases in presence of other gases like oxygen and air. [ABSTRACT FROM AUTHOR]

Abstract: We have investigated the bulk and surface electronic structures of Sm4As3 by using hard and soft X-ray photoemission spectroscopies (PESs). The valence band spectral shape changes much with photon energies ( s) due to the variation of both photoionization cross sections and bulk sensitivity. PES with the wide range of s between 220 and 2450 eV demonstrates that the valence of the Sm ions is definitely trivalent in the bulk and divalent at the surface. [Copyright &y& Elsevier]

Abstract: We have performed the bulk-sensitive high-resolution soft X-ray photoemission study of a Kondo semiconductor CeRhAs and related compounds CeNiSn and CePdSn. The comparison of the spectra of polycrystalline CePdSn on the fractured and scraped surfaces show that the fracturing of the samples is much better than the scraping in order to obtain intrinsic photoemission spectra. The Ce 4d core-level spectra show clear differences in the electronic states among the materials. [Copyright &y& Elsevier]

Abstract: The high-energy core-level photoemission spectroscopy (PES) and angle-resolved photoemission spectroscopy (ARPES) measurements have been performed for La2−xSrxCuO4 (LSCO). Polar-angle dependence of the Cu core-level PES has revealed a discrepancy between bulk and surface. We have observed by the high-energy ARPES that the Fermi surface of LSCO with is electron-like, in contrast to previous low-energy ARPES results. [Copyright &y& Elsevier]

Abstract: The metal–insulator (MI) transition in quasi-one-dimensional compound V6O13 has been investigated by angle-resolved photoemission spectroscopy (ARPES) at the photon energy of  eV using synchrotron radiation and optical study below 2 eV. Along the direction, a clear Fermi cutoff and a band dispersion near are observed in the ARPES spectra. The energy distribution curves (EDC) show an opening of a gap 0.2 eV across the transition temperature  K. The ARPES at  eV is confirmed to be a bulk-sensitive spectroscopy with high resolutions in energy and momenta. [Copyright &y& Elsevier]

Abstract: We report bulk 4f and non-4f spectral functions near the Fermi level () of a Kondo semiconductor CeRhAs and its related compound CePdSn by virtue of high-resolution soft X-ray photoemission. The non-4f spectrum of CeRhAs measured at 20K shows a shoulder at the binding energy of and almost negligible spectral weight at . Although a peak similar to a tail of the Kondo resonance is observed in the 4f spectrum of CeRhAs, the intensity at is suppressed compared with those of metallic Ce compounds. These facts are attributed to signatures of the formation of a pseudo-gap in CeRhAs. [Copyright &y& Elsevier]

We have investigated the electronic structure of A-site ordered CaCu 3 Ti 4 O 12 as a function of temperature by using angle-integrated and -resolved photoemission spectroscopies. Intrinsic changes of the electronic structure have been successfully observed in the valence band region by the careful consideration of charging effects. The obtained photoemission results have revealed that the intensity of the nearly non-dispersive Cu 3 d -O 2 p hybridized bands at the binding energy of ∼2 eV increases with decreasing temperature from 300 to 120 K. This suggests that the density of the localized states, caused by the strong correlation effects, enhances as the temperature decreases. • Temperature-dependent electronic structure of A-site ordered perovskite CaCu 3 Ti 4 O 12 has been investigated by photoemission spectroscopies. • The charging effects have been carefully considered in photoemission measurements. • The intensity of the nearly non-dispersive Cu 3 d -O 2 p hybridized bands at ∼2 eV increases with decreasing temperature. • This suggests the enhancement of the density of the localized states with decreasing temperature. [ABSTRACT FROM AUTHOR]

We have performed the photoemission and inverse photoemission experiments to elucidate the origin of Mott insulating states in A-site ordered perovskite CaCu 3 Ti 4 O 12 (CCTO). Experimental results have revealed that Cu 3 d –O 2 p hybridized bands, which are located around the Fermi level in the prediction of the local-density approximation (LDA) band calculations, are actually separated into the upper Hubbard band at ~1.5 eV and the lower Hubbard band at ~−1.7 eV with a band gap of ~1.5–1.8 eV. We also observed that Cu 3 d peak at ~−3.8 eV and Ti 3 d peak at ~3.8 eV are further away from each other than as indicated in the LDA calculations. In addition, it is found that the multiplet structure around −9 eV includes a considerable number of O 2 p states. These observations indicate that the Cu 3 d and Ti 3 d electrons hybridized with the O 2 p states are strongly correlated, which originates in the Mott-insulating states of CCTO. [ABSTRACT FROM AUTHOR]

We studied magnetism and morphology of metastable bcc Co nanostructures on Au(001) by x-ray magnetic circular dichroism in combination with scanning tunneling microscopy and photoelectron emission microscopy. While room-temperature deposition of Co onto Au(001) leads to the formation of bcc Co thin films with pure in-plane magnetization, postannealing of these thin films at 500 K drastically changes the morphology to bcc Co islands embedded in Au. In accordance with this morphological change, we find that an out-of-plane magnetization emerges additionally and the coexistence of in-plane and out-of-plane remanent magnetizations is observed for the islands. The nanostructure-size dependence of magnetic moments suggests that the magnetization easy axis of the island changes from the in-plane to the out-of-plane direction with decreasing nanostructure size. Such a spin reorientation transition is likely due to the increased fractional population of rim atoms generating the out-of-plane magnetization in the smaller islands. The observed out-of-plane remanent magnetization of the smaller islands indicates their large magnetic anisotropy. [ABSTRACT FROM AUTHOR]

Bulk-sensitive hard x-ray photoemission spectroscopy (HAXPES) reveals for as-grown epitaxial films of half-metallic ferromagnetic CrO2(100) a pronounced screening feature in the Cr 2p3/2 core level and an asymmetry in the O 1s core level. This gives evidence of a finite, metal-type Fermi edge, which is surprisingly not observed in HAXPES. A spectral weight shift in HAXPES to below the Fermi energy is attributed to single-ion recoil effects due to high-energy photoelectrons. In conjunction with inverse PES the intrinsic correlated Mott-Hubbard-type electronic structure is unraveled, yielding an averaged Coulomb correlation energy Uav ≅ 3.2 eV. [ABSTRACT FROM AUTHOR]

The material-specific electronic band structure of the electron-doped high- T c cuprate Nd1.85Ce0.15CuO4 (NCCO) is calculated in the pseudogap regime using the recently developed generalized LDA + DMFT + Σ k scheme. The LDA/DFT (density-functional theory within local density approximation) provides model parameters (hopping integral values and local Coulomb interaction strength) for the one-band Hubbard model, which is solved by the DMFT (dynamical mean-field theory). To take pseudogap fluctuations into account, the LDA + DMFT is supplied with an “external” k-dependent self-energy Σ k that describes interaction of correlated conducting electrons with nonlocal Heisenberg-like antiferromagnetic (AFM) spin fluctuations responsible for the pseudogap formation. Within this LDA + DMFT + Σ k approach, we demonstrate the formation of pronounced hot spots on the Fermi surface (FS) map in NCCO, opposite to our recent calculations for Bi2Sr2CaCu2O8 − δ (Bi2212), which have produced a rather extended region of the FS “destruction.” There are several physical reasons for this fact: (i) the hot spots in NCCO are located closer to the Brillouin zone center; (ii) the correlation length ξ of AFM fluctuations is longer for NCCO; (iii) the pseudogap potential Δ is stronger than in Bi2212. Comparison of our theoretical data with recent bulk-sensitive high-energy angle-resolved photoemission (ARPES) data for NCCO provides good semiquantitative agreement. Based on that comparison, an alternative explanation of the van Hove singularity at −0.3 eV is proposed. Optical conductivity for both Bi2212 and NCCO is also calculated within the LDA + DMFT + Δ k scheme and is compared with experimental results, demonstrating satisfactory agreement. [ABSTRACT FROM AUTHOR]

We have carried out the bulk-sensitive and high-resolution soft x-ray photoelectron spectroscopy on Lu substituted intermediate-valence compound Yb1-xLuxAl3 (x = 0.4) at temperatures from 200 to 20 K. The temperature dependences of the bulk Yb 4f photoelectron spectra revealed in our preceding works on high purity YbAl3 have not been observed in this Lu substituted system. The temperature dependences of the bulk Yb 4f peak positions and the Yb valence in this system can be well reproduced by the single impurity Anderson model (SIAM), whereas the spectral behaviors in YbAl3 were not at all reproduced by the SIAM. These results confirm the importance of the Kondo lattice effects for YbAl3, for which the coherent lattice periodicity plays essential roles. [ABSTRACT FROM AUTHOR]

Abstract: The leaching rate of chalcopyrite (CuFeS2) in H2SO4 solutions depends on the redox potential determined by the concentration ratio of Fe3+ to Fe2+, and the rate is higher at redox potentials below a critical value (critical potential). In actual leaching systems, different metal ions are released from coexisting minerals to the aqueous phase. The present study investigated the effects of coexisting metal ions on the critical potential of chalcopyrite leaching. Shaking-flask leaching experiments were carried out with 0.1 g of ground chalcopyrite and 10 cm3 of 0.1 kmol m−3 H2SO4 containing 0.1 kmol m−3 Fe2+ and 0.001 kmol m−3 of the metal ions at 298 K in air. The initial redox potential was adjusted by adding Fe3+, and the amount of Cu extracted after 24 h was investigated as a function of the potential. The results indicate that the critical potential increases by the addition of Ag+ or Bi3+ but is not affected by Pd2+, Hg2+, Cd2+, Zn2+, Ni2+, Co2+, or Mn2+. The results were interpreted by a reaction model assuming the formation of intermediate Cu2S due to the reduction of chalcopyrite and subsequent oxidation of the Cu2S at potentials below the critical potential. Catalytic effects of metal ions on chalcopyrite leaching are also discussed based on the experimental results and the proposed model. [Copyright &y& Elsevier]

Abstract: Zeta-potential measurements were made to determine the electric state of phosphor materials on the basis of which a feasibility study could be performed for the use of flotation in the recovery of fine (d 50 <13 μm) rare earth phosphors from waste fluorescent lamps. Tests were carried out with pure specimens of white (calcium halo-phosphate), red, green and blue (rare earth) phosphors, with a 17:1:1:1 ratio of their mixture, and with actual waste phosphor materials. The effects of a cationic (dodecyl ammonium acetate, DAA) and two anionic (sodium dodecyl sulfate (SDS) and sodium oleate (NaOl)) collectors on the floatability of materials, as well as that of Na2SiO3 dispersant on the separation characteristics, were investigated at different pH ranges. The process, applied to actual discarded waste phosphors gave, in a two-stage separation scheme, sink products assaying 17.7–23.8% and 21.5–25.9% rare earth phosphors for DAA and SDS flotation, respectively. The recovery and Newton''s efficiency were about 70–90% and 0.26–0.37, 66–82% and 0.18–0.20, respectively for DAA and SDS flotation. [Copyright &y& Elsevier]

Abstract: Experiments were carried out with waste phosphors collected during the recycling of end-of-life fluorescent lamps to obtain a highly enriched phosphors product as starting material for the better extraction of rare earth elements. The aim of this work was therefore to separate low-density calcium halo-phosphate phosphors from high-density rare earth-activated phosphors through dense-medium centrifugation (with di-iodomethane as organic dense-medium). The feasibility of the process and the conditions for a good separation (higher Newton''s efficiency) appear to be a function of the rotation speed of the centrifugal separator, the pulp concentration and the adsorption of a surfactant (sodium oleate, NaOl) during the pre-treatment stage. The effect of the centrifugation time was less pronounced. Through this study, a sink product assaying 48.61% of rare earth-activated phosphors could be recovered from waste phosphor materials pre-treated with 5×10−5 mol/dm3 of sodium oleate (NaOl) surfactant. The Newton''s efficiency and recovery of the separation were 0.84 and 97.34%, respectively. The process feasibility was reinforced by the possibility to recover, through laboratory batch tests, more than 99.8% of the di-iodomethane (CH2I2). [Copyright &y& Elsevier]

Abstract: Soft and hard X-ray photoelectron spectroscopy (SX- and HAXPES) has been performed for strongly correlated transition-metal oxides and rare-earth compounds in order to reveal the bulk electronic structures and/or the bulk Fermi surfaces. The variation of the bulk V 3 spectrum for SrCaVO depending on and the feature of the Fermi surfaces for SrCaRuO is consistent with other bulk-sensitive measurements and band structure calculations, respectively. It has been demonstrated for rare-earth compounds that the application of the HAXPES enables us to obtain more reliable information on the bulk electronic structures and valences. [Copyright &y& Elsevier]

Abstract: The electronic states of in the two-dimensional metal phase have been revealed by the high-resolution Mn resonant photoemission. The vanishingly weak intensity at indicates an anomalous metal due to the two-dimensionality of the electronic states. [Copyright &y& Elsevier]

Abstract: We have performed the bulk sensitive Mn 2p–3d resonant photoemission for Nd1−xSrxMnO3 (, 0.47, 0.50, 0.63) in order to reveal the Mn 3d electronic states. We will report the temperature and doping dependence of the Mn 3d spectral functions. The sudden spectral change for across the FM-COI transition shows the strong influence of the charge-ordering on the Mn 3d electronic states. [Copyright &y& Elsevier]

Abstract: Bulk electronic structures of Pr-based filled skutterudites and their reference materials have been investigated by bulk-sensitive photoemission spectroscopy using soft and hard X-rays. For Pr – resonance, a strong intensity in the vicinity of Fermi level () is observed only for PrFe4P12. Furthermore, PrFe4P12 has the significant spectral weight of the final state in Pr core-level spectrum. We interpret that the observed prominent intensity just below arises from a Kondo resonance due to the strong hybridization between the Pr and conduction states. [Copyright &y& Elsevier]

Abstract: We have studied electronic structures of VO by soft and hard X-ray synchrotron core-level photoelectron spectroscopy. In our measurements, temperature and photon energy dependences of the V 2p core-level spectra are observed. Remarkable spectral changes are observed across the metal-insulator transition (MIT) at . A clear shoulder structure is observed on the lower binding energy side of the V peak in the metallic phase. This shoulder structure, being stronger for larger h, is interpreted as the well-screened feature by bulk conduction electrons. [Copyright &y& Elsevier]