Simple solution-processed CuO{sub X} as anode buffer layer for efficient organic solar cells

Energy Technology Data Exchange (ETDEWEB)

Shen, Wenfei [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Institute of Hybrid Materials, The Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Yang, Chunpeng [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Bao, Xichang, E-mail: baoxc@qibebt.ac.cn [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Sun, Liang; Wang, Ning [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Tang, Jianguo [Institute of Hybrid Materials, The Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Chen, Weichao [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Yang, Renqiang, E-mail: yangrq@qibebt.ac.cn [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China)

2015-10-15

Graphical abstract: - Highlights: • Simple solution-processed CuO{sub X} hole transport layer for efficient organic solar cell. • Good photovoltaic performances as hole transport layer in OSCs with P3HT and PBDTTT-C as donor materials. • The device with CuO{sub X} as hole transport layer shows great improved stability compared with that of device with PEDOT:PSS as hole transport layer. - Abstract: A simple, solution-processed ultrathin CuO{sub X} anode buffer layer was fabricated for high performance organic solar cells (OSCs). XPS measurement demonstrated that the CuO{sub X} was the composite of CuO and Cu{sub 2}O. The CuO{sub X} modified ITO glass exhibit a better surface contact with the active layer. The photovoltaic performance of the devices with CuO{sub X} layer was optimized by varying the thickness of CuO{sub X} films through changing solution concentration. With P3HT:PC{sub 61}BM as the active layer, we demonstrated an enhanced PCE of 4.14% with CuO{sub X} anode buffer layer, compared with that of PEDOT:PSS layer. The CuO{sub X} layer also exhibits efficient photovoltaic performance in devices with PBDTTT-C:PC{sub 71}BM as the active layer. The long-term stability of CuO{sub X} device is better than that of PEDOT:PSS device. The results indicate that the easy solution-processed CuO{sub X} film can act as an efficient anode buffer layer for high-efficiency OSCs.

Simulation of YBa{sub 2}Cu{sub 3}O{sub 7}/MgO surface growth

Energy Technology Data Exchange (ETDEWEB)

Mohammadizadeh, M.R. [Superconductivity Research Laboratory (SRL), Department of Physics, University of Tehran, North Karegar Ave., P.O. Box 14395-547, Tehran (Iran); Computational Physical Sciences Research Laboratory, Department of Nano-Science, Institute for Studies in Theoretical Physics and Mathematics (IPM), P.O. Box 19395-5531, Tehran (Iran); Safari, N.; Kia, M.; Savaloni, H. [Superconductivity Research Laboratory (SRL), Department of Physics, University of Tehran, North Karegar Ave., P.O. Box 14395-547, Tehran (Iran)

2006-09-15

For surface growth simulation of YBa{sub 2}Cu{sub 3}O{sub 7} on MgO substrate, binding energies between each two different Y, Ba, Cu, O, and Mg atoms were calculated by ab initio pseudopotential density functional theory approach. Then, simulation of YBa{sub 2}Cu{sub 3}O{sub 7} growth was performed by a simple two dimensional model based on the ballistic aggregation of hard discs. By increasing the substrate temperature, the atomic layers distribution is more condensed and the nanometric surface roughness decreases. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Copper Selenidophosphates Cu4P2Se6, Cu4P3Se4, Cu4P4Se3, and CuP2Se, Featuring Zero-, One-, and Two-Dimensional Anions.

Science.gov (United States)

Kuhn, Alexander; Schoop, Leslie M; Eger, Roland; Moudrakovski, Igor; Schwarzmüller, Stefan; Duppel, Viola; Kremer, Reinhard K; Oeckler, Oliver; Lotsch, Bettina V

2016-08-15

Five new compounds in the Cu/P/Se phase diagram have been synthesized, and their crystal structures have been determined. The crystal structures of these compounds comprise four previously unreported zero-, one-, and two-dimensional selenidophosphate anions containing low-valent phosphorus. In addition to two new modifications of Cu4P2Se6 featuring the well-known hexaselenidohypodiphosphate(IV) ion, there are three copper selenidophosphates with low-valent P: Cu4P3Se4 contains two different new anions, (i) a monomeric (zero-dimensional) selenidophosphate anion [P2Se4](4-) and (ii) a one-dimensional selenidophosphate anion [Formula: see text], which is related to the well-known gray-Se-like [Formula: see text] Zintl anion. Cu4P4Se3 contains one-dimensional [Formula: see text] polyanions, whereas CuP2Se contains the 2D selenidophosphate [Formula: see text] polyanion. It consists of charge-neutral CuP2Se layers separated by a van der Waals gap which is very rare for a Zintl-type phase. Hence, besides black P, CuP2Se constitutes a new possible source of 2D oxidized phosphorus containing layers for intercalation or exfoliation experiments. Additionally, the electronic structures and some fundamental physical properties of the new compounds are reported. All compounds are semiconducting with indirect band gaps of the orders of around 1 eV. The phases reported here add to the structural diversity of chalcogenido phosphates. The structural variety of this family of compounds may translate into a variety of tunable physical properties.

A two-dimensional layered Cd(II) coordination polymer with a three-dimensional supramolecular architecture incorporating mixed multidentate N- and O-donor ligands.

Science.gov (United States)

Huang, Qiu-Ying; Su, Ming-Yang; Meng, Xiang-Ru

2015-06-01

The combination of N-heterocyclic and multicarboxylate ligands is a good choice for the construction of metal-organic frameworks. In the title coordination polymer, poly[bis{μ2-1-[(1H-benzimidazol-2-yl)methyl]-1H-tetrazole-κ(2)N(3):N(4)}(μ4-butanedioato-κ(4)O(1):O(1'):O(4):O(4'))(μ2-butanedioato-κ(2)O(1):O(4))dicadmium], [Cd(C4H4O4)(C9H8N6)]n, each Cd(II) ion exhibits an irregular octahedral CdO4N2 coordination geometry and is coordinated by four O atoms from three carboxylate groups of three succinate (butanedioate) ligands and two N atoms from two 1-[(1H-benzimidazol-2-yl)methyl]-1H-tetrazole (bimt) ligands. Cd(II) ions are connected by two kinds of crystallographically independent succinate ligands to generate a two-dimensional layered structure with bimt ligands located on each side of the layer. Adjacent layers are further connected by hydrogen bonding, leading to a three-dimensional supramolecular architecture in the solid state. Thermogravimetric analysis of the title polymer shows that it is stable up to 529 K and then loses weight from 529 to 918 K, corresponding to the decomposition of the bimt ligands and succinate groups. The polymer exhibits a strong fluorescence emission in the solid state at room temperature.

Layer-by-layer deposition of superconducting Sr-Ca-Cu-O films by the spray pyrolysis technique

International Nuclear Information System (INIS)

Pawar, S.H.; Pawaskar, P.N.; Ubale, M.J.; Kulkarni, S.B.

1995-01-01

Layer-by-layer deposition of Sr-Ca-Cu-O films has been carried out using the spray pyrolysis technique. Reagent-grade nitrates of strontium, calcium and copper were used to prepare starting solutions for spray pyrolysis. A two-step procedure was used for every layer of the constituents in the sequence Sr-Cu-Ca-Cu-Sr: first, deposition onto silver substrate at 350 C, then firing at T≥450 C, both at atmospheric pressure. The films were 2-3 μm thick and showed adequate adhesion to the substrate. The films were then characterised by studying their electron micrographs, X-ray diffraction patterns and electrical resistivity. The films showed superconductivity below 104 K. ((orig.))

Critical current density of four-CuO2-layer T1Ba2Ca3Cu4O11-δ

International Nuclear Information System (INIS)

Zhang, L.; Liu, J.Z.; Shelton, R.N.

1998-01-01

Full text: A key requirement for technological application is to have superconductors with high critical current density at practical operating temperatures and magnetic fields. The critical current density is strongly related to underlying properties of high T c superconductors, such as layering, anisotropy and other intrinsic material structures. The thallium-based superconductors attracted much attention at early stage mainly due to their high superconducting transitions. Recent studies show that these materials appear to be a better choice for achieving higher critical current density because of a stronger interlayer coupling between superconducting layers. Single crystals of TlBa 2 Ca 3 Cu 4 O 11-δ were grown by a self-flux method. This material is a strong-layered superconductor with four-CuO 2 -planes in a unit cell and a superconducting transition temperature of 128K. Our experimental results show that TlBa 2 Ca 3 Cu 4 O 11-δ crystals have high irreversibility line, large critical current density and high upper critical field. The impact of layering and the number of Cu-O layers on flux pinning, critical current density and other magnetic properties will also be discussed

Electronic structure in Nd2-xCexCuO4 and Pr2-xCexCuO4 studied by two dimensional angular correlation of positron annihilation radiations

International Nuclear Information System (INIS)

Kondo, H.; Kubota, T.; Nakashima, H.; Tanigawa, S.; Hidaka, Y.

1992-01-01

The electronic structure in Nd 2-x Ce x CuO 4 and Pr 2-x Ce x CuO 4 , which are high-Tc-superconducting materials, was studied by two dimensional angular correlation of positron annihilation radiations (2D-ACAR). The 2D-ACAR measurements were carried out for the samples with and without the doping in the region of the normal conducting states. The three dimensional momentum density has been reconstructed by the image reconstruction technique based on a direct Fourier transformation. The electron momentum density has been reduced into that in the reduced zone scheme by using the LCW folding procedure. The reduced electron momentum density distributions are almost flat, so the electronic structure seem to be regarded as that in semiconductor or insulator. The differences in the density distributions between with and without the doping were observed. These are thought to represent the change of the electronic structure

Room-temperature synthesis of three-dimensional porous ZnO@CuNi hybrid magnetic layers with photoluminescent and photocatalytic properties

Science.gov (United States)

Guerrero, Miguel; Zhang, Jin; Altube, Ainhoa; García-Lecina, Eva; Roldan, Mònica; Baró, Maria Dolors; Pellicer, Eva; Sort, Jordi

2016-01-01

Abstract A facile synthetic approach to prepare porous ZnO@CuNi hybrid films is presented. Initially, magnetic CuNi porous layers (consisting of phase separated CuNi alloys) are successfully grown by electrodeposition at different current densities using H2 bubbles as a dynamic template to generate the porosity. The porous CuNi alloys serve as parent scaffolds to be subsequently filled with a solution containing ZnO nanoparticles previously synthesized by sol-gel. The dispersed nanoparticles are deposited dropwise onto the CuNi frameworks and the solvent is left to evaporate while the nanoparticles impregnate the interior of the pores, rendering ZnO-coated CuNi 3D porous structures. No thermal annealing is required to obtain the porous films. The synthesized hybrid porous layers exhibit an interesting combination of tunable ferromagnetic and photoluminescent properties. In addition, the aqueous photocatalytic activity of the composite is studied under UV−visible light irradiation for the degradation of Rhodamine B. The proposed method represents a fast and inexpensive approach towards the implementation of devices based on metal-semiconductor porous systems, avoiding the use of post-synthesis heat treatment steps which could cause deleterious oxidation of the metallic counterpart, as well as collapse of the porous structure and loss of the ferromagnetic properties. PMID:27877868

Cu-O network dependence of optical charge-transfer gaps and spin-pair excitations in single-CuO2-layer compounds

International Nuclear Information System (INIS)

Tokura, Y.; Koshihara, S.; Arima, T.; Takagi, H.; Ishibashi, S.; Ido, T.; Uchida, S.

1990-01-01

Spectra of optical conductivity and magnon Raman scattering have been investigated in single crystals of a parent family of cuprate superconductors with various types of Cu-O single-layer networks. The analysis of the spectra shows the systematic dependence of the charge-transfer gaps and covalent character of Cu-O bonds on the pattern of the Cu-O network, while the spin-exchange energy is rather convergent for all the single-CuO 2 -sheet compounds

Theoretical calculations of oxygen relaxation in YBa2Cu3O6+x ceramics

Science.gov (United States)

Mi, Y.; Schaller, R.; Sathish, S.; Benoit, W.

1991-12-01

A two-dimensional theoretical model of stress-induced point-defect relaxation in a layered structure is presented, with a detailed discussion of the special case of YBa2Cu3O6+x. The experimental results of oxygen relaxation in YBa2Cu3O6+x can be explained qualitatively by this model.

Positron two-dimensional angular-correlation-of-annihilation-radiation study of untwinned YBa2Cu3O6.9 in the a-axis projection

International Nuclear Information System (INIS)

Smedskjaer, L.C.; Bansil, A.; Welp, U.; Fang, Y.; Bailey, K.G.

1992-01-01

We present a two-dimensional (2D)-ACAR positron annihilation study of an untwinned YBa 2 Cu 3 O 6.9 metallic sample in the a-axis projection; all existing data from untwinned samples have employed the c projection. The data show a clear presence of the Cu-O chain related ridge Fermi surface extending along the ΓZ direction and two associated umklapp images at higher momenta. These results are consistent with the previously investigated c projection of the momentum density in YBa 2 Cu 3 O 6.9 and do not appear to indicate a strong localization of these electron states along the c direction. We compare and contrast the structures in 2D-ACAR's in the a and c projections, delineating similarities and differences between the results for the two projections

Study of Cu2O\\ZnO nanowires heterojunction designed by combining electrodeposition and atomic layer deposition

Science.gov (United States)

Makhlouf, Houssin; Weber, Matthieu; Messaoudi, Olfa; Tingry, Sophie; Moret, Matthieu; Briot, Olivier; Chtoutou, Radhouane; Bechelany, Mikhael

2017-12-01

Cu2O/ZnO nanowires (NWs) heterojunctions were successfully prepared by combining Atomic layer Deposition (ALD) and Electrochemical Deposition (ECD) processes. The crystallinity, morphology and photoconductivity properties of the Cu2O/ZnO nanostructures have been investigated. The properties of the Cu2O absorber layer and the nanostructured heterojunction were studied in order to understand the mechanisms lying behind the low photoconductivity measured. It has been found that the interface state defects and the high resistivity of Cu2O film were limiting the photovoltaic properties of the prepared devices. The understanding presented in this work is expected to enable the optimization of solar cell devices based on Cu2O/ZnO nanomaterials and improve their overall performance.

Electronic structure in Bi2Sr2CaCu2O8 studied by two dimensional angular correlation of positron annihilation radiations

International Nuclear Information System (INIS)

Kondo, H.; Kubota, T.; Nakashima, N.; Tanigawa, S.; Minami, F.; Takekawa, S.

1992-01-01

Electronic structure in one of high-Tc-sperconducting materials, Bi 2 Sr 2 CaCu 2 O 8 , was studied by two dimensional angular correlation of positron annihilation radiations (2D-ACAR). The measurements were performed for Bi 2 Sr 2 CaCu 2 O 8 at room temperature and 24K; in the normal and superconducting states. The three dimensional electron momentum density ρ(p) has been reconstructed by using the image reconstruction technique based on a direct Fourier transportation. The reconstructed electron momentum density ρ(p) has been reduced into the reduced electron momentum density n(k) by using the LCW folding procedure. They are compared with that for Cu and Si. The difference in the density distributions between both states was observed. This may be attributed to the smearing by the reduced thermal momenta of positrons. But there is a possibility that the difference is due to the phase transition

Preparation of thin layers of BiSrCaCuO by method MOCVD

International Nuclear Information System (INIS)

Beran, P.; Stejskal, J.; Strejc, A.; Nevriva, M.; Sedmibudsky, D.; Leitner, J.

1999-01-01

Preparation of superconducting material on the basis mixed oxides of BiSrCaCuO by chemical vapour deposition (CVD) method is described. Surface morphology and concentration profiles of elements were analyzed by scanning electron microscope and microprobe. Phase of layers was analysed by X-ray diffraction (radiation of Cu kα ). Samples of thin layers were characterized by magnetic susceptibility in temperature interval 10 to 150 K. Obtained results confirm formation of superconducting phases Bi 2 Sr 2 Ca 1 Cu 2 O x and Bi 2 Sr 2 Xa 2 Cu 3 O x

Controlling the Performance of P-type Cu2O/SnO Bilayer Thin-Film Transistors by Adjusting the Thickness of the Copper Oxide Layer

KAUST Repository

Al-Jawhari, Hala A.

2014-11-11

The effect of copper oxide layer thickness on the performance of Cu2O/SnO bilayer thin-film transistors was investigated. By using sputtered Cu2O films produced at an oxygen partial pressure, Opp, of 10% as the upper layer and 3% Opp SnO films as the lower layer we built a matrix of bottom-gate Cu2O/SnO bilayer thin-film transistors of different thickness. We found that the thickness of the Cu2O layer is of major importance in oxidation of the SnO layer underneath. The thicker the Cu2O layer, the more the underlying SnO layer is oxidized, and, hence, the more transistor mobility is enhanced at a specific temperature. Both device performance and the annealing temperature required could be adjusted by controlling the thickness of each layer of Cu2O/SnO bilayer thin-film transistors.

Geometric distribution of CuO chains in YBa2Cu3O6+x

International Nuclear Information System (INIS)

Matic, V.M.; Lazarov, N.Dj.

2006-01-01

Statistics of CuO chains in basal planes of YBa 2 Cu 3 O 6+x high-T c superconductor has been studied in terms of two dimensional asymmetric next-to-nearest-neighbor Ising (ASYNNNI) model, with accentuation on distribution of CuO chains per different chain lengths. It has been shown that the fraction p(l) of CuO chains containing l oxygen ions (i.e., having the length equal to l), satisfies so-called ''law of geometric distribution''p(l)=ω(1-ω) l-1 , where the quantity ω is equal to the inverse of average chain length l av in the system, for given values of oxygen content x and temperature T. In the case of ortho-II (OII) structural phase, the geometric chain probability distribution is shown to hold separately for each of two different sublattices of oxygen sites, commonly known as α 1 and α 2 , with respectively defined l av α 1 (x,T) and l av α 2 (x,T). The theoretically derived result of the chain probability distribution p(l) is shown to be in a remarkable agreement with the results obtained out of extensive Monte Carlo calculations that were made within region of stability of orthorhombic structural phases in (x,T) space. The relevance of chain length distribution for accurate count of the number of transferred electronic holes to superconducting CuO 2 layers has been pointed out and expression for hole concentration has been derived. The concept of critical chain length for charge transfer mechanism was briefly discussed

Crystal structure and magnetism of layered perovskites compound EuBaCuFeO5

Science.gov (United States)

Lal, Surender; Mukherjee, K.; Yadav, C. S.

2018-04-01

Layered perovskite compounds have interesting multiferroic properties.YBaCuFeO5 is one of the layered perovskite compounds which have magnetic and dielectric transition above 200 K. The multiferroic properties can be tuned with the replacement of Y with some other rare earth ions. In this manuscript, structural and magnetic properties of layered perovskite compound EuBaCuFeO5 have been investigated. This compound crystallizes in the tetragonal structure with P4mm space group and is iso-structural with YBaCuFeO5. The magnetic transition has been found to shift to 120 K as compared to YBaCuFeO5 which has the transition at 200 K. This shift in the magnetic transition has been ascribed to the decrease in the chemical pressure that relaxes the magnetic moments.

High Tc superconductivity in YBa2Cu3O7-x studied by PAC and PAS

International Nuclear Information System (INIS)

Zhu Shengyun; Li Anli; Zheng Shengnan; Huang Hanchen; Li Donghong; Din Honglin; Du Hongshan; Sun Hancheng

1993-01-01

High T c superconductivity has been investigated in YBaCuO by both perturbed angular correlation and positron annihilation spectroscopy techniques as a function of temperature from 77 to 300 K. An abrupt change has been observed in the positron lifetime and Doppler broadening and the electric field gradient and its asymmetry parameter across T c , indicating a transition of two- to one-dimensional Cu-O-Cu chain structure and a charge transfer from CuO layers to CuO chains. An anomaly of the normal state has been demonstrated around 125 K, which is attributed to the structural instability. (orig.)

A comprehensive study of magnetic exchanges in the layered oxychalcogenides Sr 3 Fe 2 O 5 Cu 2 Q 2 ( Q = S, Se)

Energy Technology Data Exchange (ETDEWEB)

Lü, Minfeng; Mentré, Olivier; Gordon, Elijah E.; Whangbo, Myung-Hwan; Wattiaux, Alain; Duttine, Mathieu; Tiercelin, Nicolas; Kabbour, Houria

2017-12-01

The layered oxysulfide Sr3Fe2O5Cu2S2 was prepared, and its crystal structure and magnetic properties were characterized by synchrotron X-ray diffraction (XRD), powder neutron diffraction (PND), Mössbauer spectroscopy measurements and by density functional theory (DFT) calculations. In addition, the spin exchange interactions leading to the ordered magnetic structure of Sr3Fe2O5Cu2S2 were compared with those of its selenium analogue Sr3Fe2O5Cu2Se2. The oxysulfide Sr3Fe2O5Cu2S2 adopts a G-type antiferromagnetic (AFM) structure at a temperature in the range 485–512 K, which is comparable with the three-dimensional (3D) AFM ordering temperature, TN ≈ 490 K, found for Sr3Fe2O5Cu2Se2. Consistent with this observation, the spin exchange interactions of the magnetic (Sr3Fe2O5)2+ layers are slightly greater (but comparable) for oxysulfide than for the oxyselenide. Attempts to reduce or oxidize Sr3Fe2O5Cu2S2 using topochemical routes yield metallic Fe.

Displacement waves in La2CuO(4-delta) and La(1.85)Sr(0.15)CuO(4-delta)

Science.gov (United States)

Kajitani, Tsuyoshi; Onozuka, Takashi; Yamaguchi, Yasuo; Hirabayashi, Makoto; Syono, Yasuhiko

1987-11-01

Structural investigation of orthorhombic La2CuO(4-delta) and La(1.85)Sr(0.15)CuO(4-delta) was carried out by means of X-ray and neutron diffraction on the basis of the space group Cmmm. The periodic expansion/contraction type distortion of CuO6 octahedra was found in both orthorhombic compounds. The distortion is nearly one-dimensional in La2CuO(4-delta) but is two-dimensional in La(1.85)Sr(0.15)CuO(4-delta). The existence of a charge-density wave is highly possible in the structures.

Growth and characterization of p-Cu2O/n-ZnO nanorod heterojunctions prepared by a two-step potentiostatic method

International Nuclear Information System (INIS)

Jeong, Yoon Suk; Kim, Hyunghoon; Lee, Ho Seong

2013-01-01

Highlights: •p-Cu 2 O/n-ZnO heterostructures were grown by a two-step potentiostatic method. •The high-quality p-Cu 2 O/n-ZnO nanorod heterojunctions were obtained only at relatively high temperatures of 90 and 100 °C. •p-Cu 2 O/n-ZnO heterojunctions exhibited a well-defined p–n diode characteristic. -- Abstract: p-Cu 2 O/n-ZnO nanorod heterojunctions were fabricated by a two-step process. The process was performed with potentiostatic deposition of n-ZnO nanorods on conductive indium-tin-oxide (ITO) glasses followed by potentiostatic deposition of p-Cu 2 O to form p-Cu 2 O/n-ZnO nanorod heterojunctions. The deposition condition required to form the cuprous oxide layer affected significantly the formation and microstructure of the p-Cu 2 O/n-ZnO nanorod heterojunctions. In particular, the high-quality p-Cu 2 O/n-ZnO nanorod heterojunctions were obtained only at relatively high temperatures of 90 and 100 °C. The p-Cu 2 O/n-ZnO nanorod heterojunctions exhibited a well-defined p–n diode characteristic with an ideality factor of about 4.3

Displacement waves in La/sub 2/CuO(4-delta) and La(1. 85)Sr(0. 15)CuO(4-delta)

Energy Technology Data Exchange (ETDEWEB)

Kajitani, T.; Onozuka, T.; Yamaguchi, Y.; Hirabayashi, M.; Syono, Y.

1987-11-01

Structural investigation of orthorhombic La/sub 2/CuO(4-delta) and La(1.85)Sr(0.15)CuO(4-delta) was carried out by means of X-ray and neutron diffraction on the basis of the space group Cmmm. The periodic expansion/contraction type distortion of CuO6 octahedra was found in both orthorhombic compounds. The distortion is nearly one-dimensional in La/sub 2/CuO(4-delta) but is two-dimensional in La(1.85)Sr(0.15)CuO(4-delta). The existence of a charge-density wave is highly possible in the structures. 20 references.

Magnetic phase transitions in two-dimensional frustrated Cu3R(SeO3)2O2Cl. Spectroscopic study

Science.gov (United States)

Klimin, S. A.; Budkin, I. V.

2017-01-01

Using optical study of electronic spectra of rare-earth (RE) ions, magnetic phase transitions in the low-dimensional frustrated RE magnets Cu3R(SeO3)2O2Cl (R = Sm, Yb, Er, Nd, Pr, Eu) were investigated. Phase transitions were registered either by splittings of crystal-field (CF) doublets or by repulsion of CF levels of f-ions in a staggered magnetic field. Different scenarios of magnetic order in isostructural compounds of the francisite family are discussed.

Effect of the thin Ga2O3 layer in n+-ZnO/n-Ga2O3/p-Cu2O heterojunction solar cells

International Nuclear Information System (INIS)

Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

2013-01-01

The influence of inserting a Ga 2 O 3 thin film as an n-type semiconductor layer on the obtainable photovoltaic properties in Cu 2 O-based heterojunction solar cells was investigated with a transparent conductive Al-doped ZnO (AZO) thin film/n-Ga 2 O 3 thin film/p-Cu 2 O sheet structure. It was found that this Ga 2 O 3 thin film can greatly improve the performance of Cu 2 O-based heterojunction solar cells fabricated using polycrystalline Cu 2 O sheets that had been prepared by a thermal oxidization of copper sheets. The obtained photovoltaic properties in the AZO/Ga 2 O 3 /Cu 2 O heterojunction solar cells were strongly dependent on the deposition conditions of the Ga 2 O 3 films. The external quantum efficiency obtained in AZO/Ga 2 O 3 /Cu 2 O heterojunction solar cells was found to be greater at wavelengths below approximately 500 nm than that obtained in AZO/Cu 2 O heterojunction solar cells (i.e., prepared without a Ga 2 O 3 layer) at equivalent wavelengths. This improvement of photovoltaic properties is mainly attributed to a decrease in the level of defects at the interface between the Ga 2 O 3 thin film and the Cu 2 O sheet. Conversion efficiencies over 5% were obtained in AZO/Ga 2 O 3 /Cu 2 O heterojunction solar cells fabricated using an n-Ga 2 O 3 thin-film layer prepared with a thickness of 40–80 nm at an O 2 gas pressure of approximately 1.7 Pa by a pulsed laser deposition. - Highlights: • We demonstrate high-efficiency Cu 2 O-based p-n heterojunction solar cells. • A non-doped Ga 2 O 3 thin film was used as an n-type semiconductor layer. • The Ga 2 O 3 thin film was prepared at a low temperature by a low damage deposition. • p-type Cu 2 O sheets prepared by thermal oxidization of copper sheets were used. • Conversion efficiencies over 5% were obtained in AZO/n-Ga 2 O 3 /p-Cu 2 O solar cells

A new effect on the dependence of Tc on the number of Cu-O layers in the non-rare-earth ceramic superconductors

International Nuclear Information System (INIS)

Chela-Flores, J.; Martin, P.; Rodriguez-Nunez, J.J.

1988-08-01

We argue from the experimental evidence that the superconductivity in the non-rare-earth compounds is confined to two inequivalent layers of Cu-O planes where electron pairing occurs. This conjecture leads us to a set of phenomenological equations in terms of two order parameters that correctly describe the characteristic lengths of the copper oxide ceramics. The formalism developed indicates that samples with a larger number of Cu-O layers may have higher transition temperatures. The formalism suggests that in a multilayered Cu-O compound increments of T c as a function of the doping parameter will be more pronounced the larger the number of layers. (author). 12 refs

Enhancement in light harvesting ability of photoactive layer P3HT: PCBM using CuO nanoparticles

Science.gov (United States)

Tiwari, D. C.; Dwivedi, Shailendra Kumar; Dipak, Pukhrambam; Chandel, Tarun

2018-05-01

In this paper, we have synthesized CuO nanoparticles via precipitation method and incorporated CuO nanoparticles in the P3HT-poly (3-hexyl) thiophene: PCBM-[6, 6]-phenyl-C61-butyric acid methyl ester heterogeneous blend. The ratio of P3HT to CuO in the blend was varied, while maintaining the fixed ratio of PCBM. The UV-visible absorption spectra of P3HT: PCBM photoactive layer containing different weight percentages of CuO nanoparticles showed a clear enhancement in the photo absorption of the active layer. The absorption band starts from 310 nm to 750 nm for P3HT: CuO (NPs):PCBM (0.5:0.5:1). This shows that incorporation of CuO nanoparticles leads to larger absorption band. In addition, the X-ray diffraction (XRD) shows improvement in P3HT crystallinity and the better formation of CuO nanostructures.

Synthesis, structure and magnetic properties of the one-dimensional bimetallic oxide [Cu(terpy)Mo2O7

International Nuclear Information System (INIS)

Burkholder, Eric; Gabriel Armatas, N.; Golub, Vladimir; O'Connor, Charles J.; Zubieta, Jon

2005-01-01

The hydrothermal reaction of Cu(CH 3 CO 2 ) 2 .H 2 O, Na 2 MoO 4 and terpyridine at 140 deg. C for 48 h yields [Cu(terpy)Mo 2 O 7 ] (1), a bimetallic one-dimensional oxide. The structure consists of ruffled chains of edge- and corner-sharing {MoO 5 } square pyramids, decorated with {CuN 3 O 2 } '4+1' axially distorted square pyramids. The Cu(II) polyhedra are disposed so as to produce an alternating pattern of Cu-Cu distances across the {Mo 2 O 2 } rhombi of the chain of 6.25 and 6.82 A. This structural feature is reflected in the magnetic properties which are characteristic of a dimer rather than a linear chain, consistent with an alternating antiferromagnetic Heisenberg chain. -- Graphical abstract: Hydrothermal synthesis provided the one-dimensional bimetallic oxide [Cu(terpy)Mo 2 O 7 ], a material consisting of a zig-zag {Mo 2 O 7 } n 2 n - chain, decorated with {Cu(terpy)} 2+ groups exhibiting alternating short-long Cu-Cu distances between copper sites

Syntheses, crystal structures, and characterization of two new Tl{sup +}-Cu{sup 2+}-Te{sup 6+} oxides: Tl{sub 4}CuTeO{sub 6} and Tl{sub 6}CuTe{sub 2}O{sub 10}

Energy Technology Data Exchange (ETDEWEB)

Yeon, Jeongho; Kim, Sang-Hwan [Department of Chemistry, University of Houston, 136 Fleming Building, Houston, TX 77204-5003 (United States); Green, Mark A. [Department of Materials Science and Engineering, University of Maryland, College Park, MD, 20742-2115 and NIST Center for Neutron Research, National Institute of Standard and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-6103 (United States); Bhatti, Kanwal Preet; Leighton, C. [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455-0132 (United States); Shiv Halasyamani, P., E-mail: psh@uh.edu [Department of Chemistry, University of Houston, 136 Fleming Building, Houston, TX 77204-5003 (United States)

2012-12-15

Crystals and polycrystalline powders of two new oxide materials, Tl{sub 4}CuTeO{sub 6} and Tl{sub 6}CuTe{sub 2}O{sub 10}, have been synthesized by hydrothermal and solid-state methods. The materials were structurally characterized by single-crystal X-ray diffraction. Tl{sub 4}CuTeO{sub 6} and Tl{sub 6}CuTe{sub 2}O{sub 10} exhibit one dimensional anionic slabs of [CuTeO{sub 6}]{sup 4-} and [CuTe{sub 2}O{sub 10}]{sup 6-}, respectively. Common to both slabs is the occurrence of Cu{sup 2+}O{sub 4} distorted squares and Te{sup 6+}O{sub 6} octahedra. The slabs are separated by Tl{sup +} cations. For Tl{sub 4}CuTeO{sub 6}, magnetic measurements indicate a maximum at {approx}8 K in the temperature dependence of the susceptibility. Low temperature neutron diffraction data confirm no long-range magnetic ordering occurs and the susceptibility was adequately accounted for by fits to a Heisenberg alternating chain model. For Tl{sub 6}CuTe{sub 2}O{sub 10} on the other hand, magnetic measurements revealed paramagnetism with no evidence of long-range magnetic ordering. Infrared, UV-vis spectra, thermogravimetric, and differential thermal analyses are also reported. Crystal data: Tl{sub 4}CuTeO{sub 6}, Triclinic, space group P-1 (No. 2), a=5.8629(8) A, b=8.7848(11) A, c=9.2572(12) A, {alpha}=66.0460(10), {beta}=74.2010(10), {gamma}=79.254(2), V=417.70(9) A{sup 3}, and Z=2; Tl{sub 6}CuTe{sub 2}O{sub 10}, orthorhombic, space group Pnma (No. 62), a=10.8628(6) A, b=11.4962(7) A, c=10.7238(6) A, V=1339.20(13) A{sup 3}, and Z=4. - Graphical Abstract: Two new oxide materials, Tl{sub 4}CuTeO{sub 6} and Tl{sub 6}CuTe{sub 2}O{sub 10}, have been synthesized and characterized. The materials exhibit one dimensional crystal structures consisting of CuO{sub 4} and TeO{sub 6} polyhedra. Highlights: Black-Right-Pointing-Pointer Two New Tl-Te-Cu-oxides have been synthesized and structurally characterized. Black-Right-Pointing-Pointer For Tl{sub 4}CuTeO{sub 6}, magnetic measurements indicate a

Superconducting properties and microstructure of YBa2Cu3O7-δ/PrBa2Cu3O7-δ superlattices

International Nuclear Information System (INIS)

Lowndes, D.H.; Norton, D.P.; Zheng, X.Y.; Zhu, Shen

1991-10-01

Epitaxial YBa 2 Cu 3 O 7-δ /PrBa 2 Cu 3 O 7-δ (YBCO/PBCO) superlattices are tools for systematic, fundamental studies of high-temperature superconductivity. The variation of T c in YBCO/PBCO superlattices can be understood as arising from changes in the interlayer phase coupling between YBCO layers that are highly two-dimensional when they are very thin (∼1--2 c-axis unit cells) and completely isolated from each other. Single-cell-thick YBCO layers, containing isolated pairs of CuO 2 planes, are found to be superconducting at T c ∼ 20 K, in a PBCO matrix. The resistance in the superconducting transition region scales with temperature as expected for the (flux flow) resistance produced by thermally generated 2D vortices, or for a 2D array of superconducting weak links. Relative to both thin-film and single-crystal HTSc specimens, the thin superconducting layers in YBCO/PBCO superlattices exhibit a greatly expanded temperature range over which characteristic 2D dissipation can be observed, as a consequence of the enhanced anisotropy and reduced dimensionality of the YBCO layers. Scanning tunneling microscope studies reveal that YBCO films and YBCO/PBCO superlattices grow unit cell-by-unit cell by a terraced-island growth mechanism. On miscut, near-(001) substrates the terraces are epitaxially aligned with the substrate crystal lattice and spiral growth structures (screw dislocation-mediated growth) are not seen. These observations explain the steps or ''kinks'' that are seen in cross-section Z-contrast TEM images of YBCO/PBCO superlattices. The kinks may correspond physically to regions where the supercurrent must tunnel along the c- axis, and thus may be weak-link barriers. 31 refs., 7 figs

TiO2/Cu2O composite based on TiO2 NTPC photoanode for photoelectrochemical (PEC) water splitting under visible light

KAUST Repository

Shi, Le

2015-05-01

Water splitting through photoelectrochemical reaction is widely regarded as a major method to generate H2 , a promising source of renewable energy to deal with the energy crisis faced up to human being. Efficient exploitation of visible light in practice of water splitting with pure TiO2 material, one of the most popular semiconductor material used for photoelectrochemical water splitting, is still challenging. One dimensional TiO2 nanotubes is highly desired with its less recombination with the short distance for charge carrier diffusion and light-scattering properties. This work is based on TiO2 NTPC electrode by the optimized two-step anodization method from our group. A highly crystalized p-type Cu2O layer was deposited by optimized pulse potentiostatic electrochemical deposition onto TiO2 nanotubes to enhance the visible light absorption of a pure p-type TiO2 substrate and to build a p-n junction at the interface to improve the PEC performance. However, because of the real photocurrent of Cu2O is far away from its theoretical limit and also poor stability in the aqueous environment, a design of rGO medium layer was added between TiO2 nanotube and Cu2O layer to enhance the photogenerated electrons and holes separation, extend charge carrier diffusion length (in comparison with those of conventional pure TiO2 or Cu2O materials) which could significantly increase photocurrent to 0.65 mA/cm2 under visible light illumination (>420 nm) and also largely improve the stability of Cu2O layer, finally lead to an enhancement of water splitting performance.

Two-dimensional structure of poly[[[μ2-1,4-bis(pyridin-4-ylbutane]bis(μ4-pentanedioatodicopper(II] acetonitrile disolvate

Directory of Open Access Journals (Sweden)

Do Nam Lee

2017-10-01

Full Text Available In the title compound, {[Cu2(μ4-C5H6O42(μ2-C14H16N2]·2CH3CN}n, the Cu2 dinuclear units are connected by glutartate ligands, forming one-dimensional double chains. These chains, are in turn bridged by 1,4-bis(pyridin-4-ylbutane ligands to form a two-dimensional layer structure parallel to (112. The carboxylate groups of the glutarate ligand bridge two copper(II ions, forming a paddle-wheel-type Cu2(CO24 dinuclear secondary building unit. A crystallographic inversion centre is located midway between two CuII ions, with a Cu...Cu distance of 2.639 (3 Å. The coordination geometry of the unique CuII ion is slightly disorted square pyramidal, formed by four equatorial carboxylate O atoms and an axial pyridyl N atom.

Effect of Ga2O3 buffer layer thickness on the properties of Cu/ITO thin films deposited on flexible substrates

International Nuclear Information System (INIS)

Zhuang Huihui; Yan Jinliang; Xu Chengyang; Meng Delan

2014-01-01

Cu and Cu/ITO films were prepared on polyethylene terephthalate (PET) substrates with a Ga 2 O 3 buffer layer using radio frequency (RF) and direct current (DC) magnetron sputtering. The effect of Cu layer thickness on the optical and electrical properties of the Cu film deposited on a PET substrate with a Ga 2 O 3 buffer layer was studied, and an appropriate Cu layer thickness of 4.2 nm was obtained. Changes in the optoelectrical properties of Cu(4.2 nm)/ITO(30 nm) films were investigated with respect to the Ga 2 O 3 buffer layer thickness. The optical and electrical properties of the Cu/ITO films were significantly influenced by the thickness of the Ga 2 O 3 buffer layer. A maximum transmission of 86%, sheet resistance of 45 Ω/□ and figure of merit of 3.96 × 10 −3 Ω −1 were achieved for Cu(4.2 nm)/ITO(30 nm) films with a Ga 2 O 3 layer thickness of 15 nm. (semiconductor materials)

Materials science and integration bases for fabrication of (BaxSr1-x)TiO3 thin film capacitors with layered Cu-based electrodes

International Nuclear Information System (INIS)

Fan, W.; Kabius, B.; Hiller, J.M.; Saha, S.; Carlisle, J.A.; Auciello, O.; Chang, R.P.H.; Ramesh, R.

2003-01-01

The synthesis and fundamental material properties of layered TiAl/Cu/Ta electrodes were investigated to achieve the integration of Cu electrodes with high-dielectric constant (κ) oxide thin films for application to the fabrication of high-frequency devices. The Ta layer is an excellent diffusion barrier to inhibit deleterious Cu diffusion into the Si substrate, while the TiAl layer provides an excellent barrier against oxygen diffusion into the Cu layer to inhibit Cu oxidation during the growth of the high-κ layer in an oxygen atmosphere. Polycrystalline (Ba x Sr 1-x )TiO 3 (BST) thin films were grown on the Cu-based bottom electrode by rf magnetron sputtering at temperatures in the range 400-600 deg. C in oxygen, to investigate the performance of BST/Cu-based capacitors. Characterization of the Cu-based layered structure using surface analytical methods showed that two amorphous oxide layers were formed on both sides of the TiAl barrier, such that the oxide layer on the free surface of the TiAl layer correlates with TiAlO x , while the oxide layer at the TiAl/Cu interface is an Al 2 O 3 -rich layer. This double amorphous barrier layer structure effectively prevents oxygen penetration towards the underlying Cu and Ta layers. The TiAlO x interfacial layer, which has a relatively low dielectric constant compared with BST, reduced the total capacitance of the BST thin film capacitors. In addition, the layered electrode-oxide interface roughening observed during the growth of BST films at high temperature, due to copper grain growth, resulted in large dielectric loss on the fabricated BST capacitors. These problems were solved by growing the BST layer at 450 deg. C followed by a rapid thermal annealing at 700 deg. C. This process significantly reduced the thickness of the TiAlO x layer and interface roughness resulting in BST capacitors exhibiting properties suitable for the fabrication of high-performance high-frequency devices. In summary, relatively high

High T[sub c] superconductivity in YBa[sub 2]Cu[sub 3]O[sub 7-x] studied by PAC and PAS

Energy Technology Data Exchange (ETDEWEB)

Zhu Shengyun (China Inst. of Atomic Energy, Beijing, BJ (China)); Li Anli (China Inst. of Atomic Energy, Beijing, BJ (China)); Zheng Shengnan (China Inst. of Atomic Energy, Beijing, BJ (China)); Huang Hanchen (China Inst. of Atomic Energy, Beijing, BJ (China)); Li Donghong (China Inst. of Atomic Energy, Beijing, BJ (China)); Din Honglin (China Inst. of Atomic Energy, Beijing, BJ (China)); Du Hongshan (China Inst. of Atomic Energy, Beijing, BJ (China)); Sun Hancheng (China Inst. of Atomic Energy, Beijing, BJ (China))

1993-11-01

High T[sub c] superconductivity has been investigated in YBaCuO by both perturbed angular correlation and positron annihilation spectroscopy techniques as a function of temperature from 77 to 300 K. An abrupt change has been observed in the positron lifetime and Doppler broadening and the electric field gradient and its asymmetry parameter across T[sub c], indicating a transition of two- to one-dimensional Cu-O-Cu chain structure and a charge transfer from CuO layers to CuO chains. An anomaly of the normal state has been demonstrated around 125 K, which is attributed to the structural instability. (orig.)

One-dimensional CuO nanowire: synthesis, electrical, and optoelectronic devices application

Science.gov (United States)

Luo, Lin-Bao; Wang, Xian-He; Xie, Chao; Li, Zhong-Jun; Lu, Rui; Yang, Xiao-Bao; Lu, Jian

2014-11-01

In this work, we presented a surface mechanical attrition treatment (SMAT)-assisted approach to the synthesis of one-dimensional copper oxide nanowires (CuO NWs) for nanodevices applications. The as-prepared CuO NWs have diameter and the length of 50 ~ 200 nm and 5 ~ 20 μm, respectively, with a preferential growth orientation along [1 [InlineEquation not available: see fulltext.] 0] direction. Interestingly, nanofield-effect transistor (nanoFET) based on individual CuO NW exhibited typical p-type electrical conduction, with a hole mobility of 0.129 cm2V-1 s-1 and hole concentration of 1.34 × 1018 cm-3, respectively. According to first-principle calculations, such a p-type electrical conduction behavior was related to the oxygen vacancies in CuO NWs. What is more, the CuO NW device was sensitive to visible light illumination with peak sensitivity at 600 nm. The responsitivity, conductive gain, and detectivity are estimated to be 2.0 × 102 A W-1, 3.95 × 102 and 6.38 × 1011 cm Hz1/2 W-1, respectively, which are better than the devices composed of other materials. Further study showed that nanophotodetectors assembled on flexible polyethylene terephthalate (PET) substrate can work under different bending conditions with good reproducibility. The totality of the above results suggests that the present CuO NWs are potential building blocks for assembling high-performance optoelectronic devices.

Regenerable Cu-intercalated MnO2 layered cathode for highly cyclable energy dense batteries

Energy Technology Data Exchange (ETDEWEB)

Yadav, Gautam G.; Gallaway, Joshua W.; Turney, Damon E.; Nyce, Michael; Huang, Jinchao; Wei, Xia; Banerjee, Sanjoy

2017-03-06

Manganese dioxide cathodes are inexpensive and have high theoretical capacity (based on two electrons) of 617 mAh g-1, making them attractive for low-cost, energy-dense batteries. They are used in non-rechargeable batteries with anodes like zinc. Only ~10% of the theoretical capacity is currently accessible in rechargeable alkaline systems. Attempts to access the full capacity using additives have been unsuccessful. We report a class of Bi-birnessite (a layered manganese oxide polymorph mixed with bismuth oxide (Bi2O3)) cathodes intercalated with Cu2+ that deliver near-full two-electron capacity reversibly for >6,000 cycles. The key to rechargeability lies in exploiting the redox potentials of Cu to reversibly intercalate into the Bi-birnessite-layered structure during its dissolution and precipitation process for stabilizing and enhancing its charge transfer characteristics. This process holds promise for other applications like catalysis and intercalation of metal ions into layered structures. A large prismatic rechargeable Zn-birnessite cell delivering ~140 Wh l-1 is shown.

Two-dimensional condensation of physi-sorbed methane on layer-like halides

International Nuclear Information System (INIS)

Nardon, Yves

1972-01-01

Two-dimensional condensation of methane in physi-sorbed layers has been studied from sets of stepped isotherms of methane on the cleavage plane of layer-like halides (FeCl 2 , CdCl 2 , NiBr 2 , CdBr 2 , FeI 2 , CaI 2 , CaI 2 and PbI 2 ) in most cases prepared by sublimation in a rapid current of inert gas. The vertical parts of the steps of adsorption isotherms correspond to the formation of successive monomolecular layers by two-dimensional condensation. Thermodynamic analysis of experimental results, has mainly emphasized the important effect of the potential relief of adsorbent surfaces, on both the structure of the physi-sorbed layers and the two-dimensional critical temperature. From its entropy, we conclude that the first layer is a (111) plane of f.c.c.: methane which becomes more loosely packed as the dimensional compatibility of the lattices of the adsorbent and adsorbate becomes poorer. Experimental values of the two-dimensional critical temperatures in the first, second and third layers have been determined, and interpreted on the following basis. An expansion of the layer induces a lowering of the two-dimensional critical temperature by decreasing the lateral interaction energy, while a localisation of the adsorbed molecules in potential wells, when possible, induces a rise of the two-dimensional critical temperature. (author) [fr

Simple solution-processed CuOX as anode buffer layer for efficient organic solar cells

International Nuclear Information System (INIS)

Shen, Wenfei; Yang, Chunpeng; Bao, Xichang; Sun, Liang; Wang, Ning; Tang, Jianguo; Chen, Weichao; Yang, Renqiang

2015-01-01

Graphical abstract: - Highlights: • Simple solution-processed CuO X hole transport layer for efficient organic solar cell. • Good photovoltaic performances as hole transport layer in OSCs with P3HT and PBDTTT-C as donor materials. • The device with CuO X as hole transport layer shows great improved stability compared with that of device with PEDOT:PSS as hole transport layer. - Abstract: A simple, solution-processed ultrathin CuO X anode buffer layer was fabricated for high performance organic solar cells (OSCs). XPS measurement demonstrated that the CuO X was the composite of CuO and Cu 2 O. The CuO X modified ITO glass exhibit a better surface contact with the active layer. The photovoltaic performance of the devices with CuO X layer was optimized by varying the thickness of CuO X films through changing solution concentration. With P3HT:PC 61 BM as the active layer, we demonstrated an enhanced PCE of 4.14% with CuO X anode buffer layer, compared with that of PEDOT:PSS layer. The CuO X layer also exhibits efficient photovoltaic performance in devices with PBDTTT-C:PC 71 BM as the active layer. The long-term stability of CuO X device is better than that of PEDOT:PSS device. The results indicate that the easy solution-processed CuO X film can act as an efficient anode buffer layer for high-efficiency OSCs

Binary Oxide p-n Heterojunction Piezoelectric Nanogenerators with an Electrochemically Deposited High p-Type Cu2O Layer.

Science.gov (United States)

Baek, Seung Ki; Kwak, Sung Soo; Kim, Joo Sung; Kim, Sang Woo; Cho, Hyung Koun

2016-08-31

The high performance of ZnO-based piezoelectric nanogenerators (NGs) has been limited due to the potential screening from intrinsic electron carriers in ZnO. We have demonstrated a novel approach to greatly improve piezoelectric power generation by electrodepositing a high-quality p-type Cu2O layer between the piezoelectric semiconducting film and the metal electrode. The p-n heterojunction using only oxides suppresses the screening effect by forming an intrinsic depletion region, and thus sufficiently enhances the piezoelectric potential, compared to the pristine ZnO piezoelectric NG. Interestingly, a Sb-doped Cu2O layer has high mobility and low surface trap states. Thus, this doped layer is an attractive p-type material to significantly improve piezoelectric performance. Our results revealed that p-n junction NGs consisting of Au/ZnO/Cu2O/indium tin oxide with a Cu2O:Sb (cuprous oxide with a small amount of antimony) layer of sufficient thickness (3 μm) exhibit an extraordinarily high piezoelectric potential of 0.9 V and a maximum output current density of 3.1 μA/cm(2).

YBa2Cu3O7-δ/NdBa2(Cu1-xNix)3O7-δ double layers by liquid-phase epitaxial growth

International Nuclear Information System (INIS)

Yao, X.; Izumi, Toru; Hobara, Natsuro; Nakamura, Yuichi; Izumi, Teruo; Shiohara, Yuh

2001-01-01

Our present investigation has answered questions pertaining to the REBa 2 Cu 3 O 7-δ (RE123, RE=rare-earth elements)-coated conductor application when NdBa 2 (Cu 1-x Ni x ) 3 O 7-δ (Ni-NdBCO) solid solution is used as a buffer layer by the liquid-phase epitaxy(LPE) process. The NiO/Ni substrate has no substantial reaction in the Ni-saturated Nd-Ba-Cu-O liquid. There is no essential Ni interdiffusion between YBa 2 Cu 3 O 7-δ (YBCO) and Ni-NdBCO LPE thick films as evident from T c values of 90 K obtained from multilayer YBCO/Ni-NdBCO samples. (author)

One dimensional CuO nanocrystals synthesis by electrical explosion: A study on structural, optical and electronic properties

Energy Technology Data Exchange (ETDEWEB)

Krishnan, Shutesh, E-mail: shutesh.k@onsemi.com [Department of Mechanical Engineering University of Malaya, 50603 Kuala Lumpur (Malaysia); ON Semiconductor Package Innovation and Development Center, 70450 Seremban (Malaysia); Haseeb, A.S.M.A.; Johan, Mohd Rafie [Department of Mechanical Engineering University of Malaya, 50603 Kuala Lumpur (Malaysia)

2014-02-15

Highlights: • One-dimensional CuO nanoflakes were synthesized by novel wire explosion technique. • A physical synthesis method capable of producing high aspect ratio (1:16) nanocrystals. • Most energy efficient and eco-friendly synthesis of low-dimensional transition metal oxide nanocrystals. -- Abstract: One-dimensional (1D) copper oxide (CuO) nanocrystals were synthesized using a novel wire explosion in de-ionized (DI) water without any chemical additives. Highly crystalline 1D CuO nanocrystals with 1:16 aspect ratio were successfully synthesized using this technique. The chemical nature and physical structure of the nanocrystals were controlled by simply modulating the exploding medium temperature. The results showed that nanocrystals produced at explosion temperatures 65 °C and 95 °C are pure CuO with optical band-gap energy of 2.38 eV. High Resolution Transmission Electron Microscope analysis (HRTEM) indicates that the CuO nanocrystals are with growth in [1{sup ¯}11] and [1 1 1] directions. The epitaxial crystal growth kinetics of the 1D nanostructure by aggregation was discussed. The incorporation of microstructural features like edge dislocations and porosity in the growth mechanism was examined. X-ray photoelectron spectroscopy (XPS) characterization indicates the formation of high purity CuO nanocrystals with valence state +2. This study provides an energy efficient and eco-friendly synthesis method of 1D transition metal oxide nanocrystals for electronic applications.

One dimensional CuO nanocrystals synthesis by electrical explosion: A study on structural, optical and electronic properties

International Nuclear Information System (INIS)

Krishnan, Shutesh; Haseeb, A.S.M.A.; Johan, Mohd Rafie

2014-01-01

Highlights: • One-dimensional CuO nanoflakes were synthesized by novel wire explosion technique. • A physical synthesis method capable of producing high aspect ratio (1:16) nanocrystals. • Most energy efficient and eco-friendly synthesis of low-dimensional transition metal oxide nanocrystals. -- Abstract: One-dimensional (1D) copper oxide (CuO) nanocrystals were synthesized using a novel wire explosion in de-ionized (DI) water without any chemical additives. Highly crystalline 1D CuO nanocrystals with 1:16 aspect ratio were successfully synthesized using this technique. The chemical nature and physical structure of the nanocrystals were controlled by simply modulating the exploding medium temperature. The results showed that nanocrystals produced at explosion temperatures 65 °C and 95 °C are pure CuO with optical band-gap energy of 2.38 eV. High Resolution Transmission Electron Microscope analysis (HRTEM) indicates that the CuO nanocrystals are with growth in [1 ¯ 11] and [1 1 1] directions. The epitaxial crystal growth kinetics of the 1D nanostructure by aggregation was discussed. The incorporation of microstructural features like edge dislocations and porosity in the growth mechanism was examined. X-ray photoelectron spectroscopy (XPS) characterization indicates the formation of high purity CuO nanocrystals with valence state +2. This study provides an energy efficient and eco-friendly synthesis method of 1D transition metal oxide nanocrystals for electronic applications

Thermal transport in layered structure of YBa2Cu3O7-δ superconductors

Science.gov (United States)

Sharma, Rakhi; Indu, B. D.

2017-12-01

The heat transfer study in YBa2Cu3O7-δ superconductors structures is focused on the influence of the effect of scattering events in cross-plane and in-plane references. Understanding the mechanism of controlling the thermal conductivity of layered superconductors is an area of interest for nano microelectronics and thermo-electronic technological applications. The model of the thermal conduction, and phonon transport perpendicular and parallel to the layers of YBa2Cu3O7-δ are developed. It has been justified via numerical estimation and found substantial diminution in thermal conductivities in both in-plane and cross-plane directions of layered cuprate superconductors.

LaNiO3 buffer layers for high critical current density YBa2Cu3O7-δ and Tl2Ba2CaCu2O8-δ films

International Nuclear Information System (INIS)

Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

1999-01-01

We demonstrate high critical current density superconducting films of YBa 2 Cu 3 O 7-δ (YBCO) and Tl 2 Ba 2 CaCu 2 O 8-δ (Tl-2212) using LaNiO 3 (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J c (5 K, H=0) than films grown directly on a bare LaAlO 3 substrate. YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J c at all temperatures and fields compared to those grown on bare LaAlO 3 , correlating to both a-axis grain and nonsuperconducting phase formation. LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films in coated conductor applications. copyright 1999 American Institute of Physics

LaNiO3 Buffer Layers for High Critical Current Density YBa2Cu3O7δ and Tl2Ba2CaCu2O8δ Films

International Nuclear Information System (INIS)

Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.-T.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

1999-01-01

We demonstrate high critical current density superconducting films of YBa 2 Cu 3 O 7-δ (YBCO) and Tl 2 Ba 2 CaCu 2 O 8-δ (Tl-2212) using LaNiO 3 (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J c (5K, H=0) than films grown directly on a bare LaAlO 3 substrate. It is noteworthy that YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J c at all temperatures and fields compared to those grown on bare LaAlO 3 , correlating to both a-axis grain and nonsuperconducting phase formation. With additional optimization, LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films, perhaps ideally suited for coated conductor applications

Controlling the Performance of P-type Cu2O/SnO Bilayer Thin-Film Transistors by Adjusting the Thickness of the Copper Oxide Layer

KAUST Repository

Al-Jawhari, Hala A.; Caraveo-Frescas, Jesus Alfonso; Hedhili, Mohamed N.

2014-01-01

The effect of copper oxide layer thickness on the performance of Cu2O/SnO bilayer thin-film transistors was investigated. By using sputtered Cu2O films produced at an oxygen partial pressure, Opp, of 10% as the upper layer and 3% Opp SnO films

Efficient hole-transporting layer MoO_3:CuI deposited by co-evaporation in organic photovoltaic cells

International Nuclear Information System (INIS)

Barkat, L.; Khelil, A.; Hssein, M.; El Jouad, Z.; Cattin, L.; Louarn, G.; Stephant, N.; Ghamnia, M.; Addou, M.; Morsli, M.; Bernede, J.C.

2017-01-01

In order to improve hole collection at the interface anode/electron donor in organic photovoltaic cells, it is necessary to insert a hole-transporting layer. CuI was shown to be a very efficient hole-transporting layer. However, its tendency to be quite rough tends to induce leakage currents and it is necessary to use a very slow deposition rate for CuI to avoid such negative effect. Herein, we show that the co-deposition of MoO_3 and CuI avoids this difficulty and allows deposition of a homogeneous efficient hole-collecting layer at an acceptable deposition rate. Via an XPS study, we show that blending MoO_3:CuI improves the hole collection efficiency through an increase of the gap state density. This increase is due to the formation of Mo"5"+ following interaction between MoO_3 and CuI. Not only does the co-evaporation process allow for decreasing significantly the deposition time of the hole-transporting layer, but also it increases the efficiency of the device based on the planar heterojunction, CuPc/C_6_0. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Electronic structures of (Pb sub 2 Cu)Sr sub 2 Eu sub x Ce sub n sub - sub x Cu sub 2 O sub 2 sub n sub + sub 6 (n=2, 3): Effect of fluorite blocks between adjacent CuO sub 2 layers

CERN Document Server

Arai, M

2003-01-01

The electronic structures of (Pb sub 2 Cu)Sr sub 2 Eu sub x Ce sub n sub - sub x Cu sub 2 O sub 2 sub n sub + sub 6 (n = 2, 3) compounds which have fluorite blocks between two adjacent CuO sub 2 layers have been studied by using ab-initio method. It is found that the anisotropy is enhanced by inserting the fluorite blocks. The Fermi velocity perpendicular to the CuO sub 2 layers decreases as the thickness of fluorite blocks increases. The Eu substitution is found to affect both the atomic positions and electronic structures. The distance between apical oxygen and copper becomes shorter by the Eu substitution. The energy bands derived from oxygens in the fluorite blocks approach Fermi energy as the content of Eu substitution increases. (author)

Cu/Cu{sub 2}O/CuO loaded on the carbon layer derived from novel precursors with amazing catalytic performance

Energy Technology Data Exchange (ETDEWEB)

Zhao, Xiaoli, E-mail: zhaoxiaoli_zxl@126.com [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Tan, Yixin [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Wu, Fengchang, E-mail: wu_fengchang@126.com [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Niu, Hongyun [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Tang, Zhi [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Cai, Yaqi [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Giesy, John P. [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Department of Veterinary Biomedical Sciences and Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan (Canada)

2016-11-15

A simple, novel method for synthesis of Cu/Cu{sub 2}O/CuO on surfaces of carbon (Cu/Cu{sub 2}O/CuO@C) as a non-noble-metal catalyst for reduction of organic compounds is presented. Compared with noble metals, Cu/Cu{sub 2}O/CuO@C particles are more efficient and less expensive. Characterization of the Cu/Cu{sub 2}O/CuO@C composites by high-resolution transmission electron microscope (HRTEM), x-ray diffraction (XRD), infrared spectroscopy and Raman analysis, revealed that it was composed of graphitized carbon with numerous nanoparticles (100 nm in diameter) of Cu/CuO/Cu{sub 2}O that were uniformly distributed on internal and external surfaces of the carbon support. Gallic acid (GA) has been used as both organic ligand and carbon precursor with metal organic frameworks (MOFs) as the sacrificial template and metal oxide precursor in this green synthesis. The material combined the advantages of MOFs and Cu-containing materials, the porous structure provided a large contact area and channels for the pollutions, which results in more rapid catalytic degradation of pollutants and leads to greater efficiency of catalysis. The material gave excellent catalytic performance for organic dyes and phenols. In this study, Cu/Cu{sub 2}O/CuO@C was used as catalytic to reduce 4-NP, which has been usually adopted as a model reaction to check the catalytic ability. Catalytic experiment results show that 4-NP was degraded approximately 3 min by use of 0.04 mg of catalyst and the conversion of pollutants can reach more than 99%. The catalyst exhibited little change in efficacy after being utilized five times. Rates of degradation of dyes, such as Methylene blue (MB) and Rhodamine B (RhB) and phenolic compounds such as O-Nitrophenol (O-NP) and 2-Nitroaniline (2-NA) were all similar. - Highlights: • We present an effective catalyst for reductive degradation of organic dyes and phenols in water. • Compared with noble metals, Cu/Cu{sub 2}O/CuO@C particles are more efficient and less

Effect of electrodeposition and annealing of ZnO on optical and photovoltaic properties of the p-Cu2O/n-ZnO solar cells

International Nuclear Information System (INIS)

Hussain, Sajad; Cao Chuanbao; Nabi, Ghulam; Khan, Waheed S.; Usman, Zahid; Mahmood, Tariq

2011-01-01

Highlights: → The p-Cu 2 O/n-ZnO heterojunction was fabricated by using electrodeposition and rf sputtering techniques, respectively. → The effect of electrodeposition on optical and photovoltaic properties of the p-Cu 2 O/n-ZnO solar cells has been examined. → The preannealing of ZnO thin films has enhanced the efficiency of solar cells. → The efficiency of the solar cell was measured 0.46%. - Abstract: Cu 2 O/ZnO p-n heterojunction solar cells were fabricated by rf sputtering deposition of n-ZnO layer, followed by electrodeposition of p-Cu 2 O layer. The different electrodeposition potentials were applied to deposit Cu 2 O on ZnO. The particle size, crystal faces, crystallinity of Cu 2 O is important factor which determine the p-n junction interface and consequently their effect on the performance of the heterojunction solar cell. It is observed that at -0.6 V, p-Cu 2 O film generates fewer surface states in the interband region due to the termination of [1 1 0] resulting in higher efficiency (0.24%) with maximum particle size (53 nm). The bandgap of Cu 2 O at this potential is found to be 2.17 eV. Furthermore, annealing of ZnO film was performed to get rid of deteriorating one and two dimensional defects, which always reduce the performance of solar cell significantly. We found that the solar cell performance efficiency is nearly doubled by increasing the annealing temperature of ZnO thin films due to increasing electrical conductance and electron mobility. Doping studies and fine tuning of the junction morphology will be necessary to further improve the performance of Cu 2 O/ZnO heterojunction solar cells.

LaNiO(3) Buffer Layers for High Critical Current Density YBa(2)Cu(3)O(7-delta) and Tl(2)Ba(2)CaCu(2)O(8-delta) Films

Energy Technology Data Exchange (ETDEWEB)

Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.-T.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

1999-08-24

We demonstrate high critical current density superconducting films of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8{minus}{delta}} (Tl-2212) using LaNiO{sub 3} (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J{sub c} (5K, H=0) than films grown directly on a bare LaAlO{sub 3} substrate. It is noteworthy that YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J{sub c} at all temperatures and fields compared to those grown on bare LaAlO{sub 3}, correlating to both a-axis grain and nonsuperconducting phase formation. With additional optimization, LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films, perhaps ideally suited for coated conductor applications.

Inter-layer Cooper pairing of two-dimensional electrons

International Nuclear Information System (INIS)

Inoue, Masahiro; Takemori, Tadashi; Yoshizaki, Ryozo; Sakudo, Tunetaro; Ohtaka, Kazuo

1987-01-01

The authors point out the possibility that the high transition temperatures of the recently discovered oxide superconductors are dominantly caused by the inter-layer Cooper pairing of two-dimensional electrons that are coupled through the exchange of three-dimensional phonons. (author)

Two different one-dimensional structural motifs in [catena-{Cu(tacn)}2Pd(CN)4]Br2.[catena-Cu(tacn)Pd(CN)4]2.H2O (tacn is 1,4,7-triazacyclononane).

Science.gov (United States)

Kuchár, Juraj; Cernák, Juraj

2009-07-01

The title compound, catena-poly[[bis[(triazacyclononane-kappa(3)N,N',N'')copper(II)]-di-mu-cyanido-kappa(4)N:C-palladate(II)-di-mu-cyanido-kappa(4)C:N] dibromide bis[[(triazacyclononane-kappa(3)N,N',N'')copper(II)]-mu-cyanido-kappa(2)N:C-[dicyanidopalladate(II)]-mu-cyanido-kappa(2)C:N] monohydrate], {[Cu(2)Pd(CN)(4)(C(6)H(15)N(3))(2)]Br(2).[Cu(2)Pd(2)(CN)(8)(C(6)H(15)N(3))(2)].H(2)O}(n), (I), was isolated from an aqueous solution containing tacn.3HBr (tacn is 1,4,7-triazacyclononane), Cu(2+) and tetracyanidopalladate(2-) anions. The crystal structure of (I) is essentially ionic and built up of 2,2-electroneutral chains, viz. [Cu(tacn)(NC)-Pd(CN)(2)-(CN)-], positively charged 2,4-ribbons exhibiting the composition {[Cu(tacn)(NC)(2)-Pd(CN)(2)-Cu(tacn)](2n+)}(n), bromide anions and one disordered water molecule of crystallization. The O atom of the water molecule occupies two unique crystallographic positions, one on a centre of symmetry, which is half occupied, and the other in a general position with one-quarter occupancy. One of the tacn ligands also exhibits disorder. The formation of two different types of one-dimensional structural motif within the same structure is a unique feature of this compound.

Multiple Scattering Analysis of Cu - K EXAFS in Bi2Sr1.5 Cu2O8+δ

International Nuclear Information System (INIS)

Roehler, J.; Cruesemann, R.

1995-01-01

We have analyzed the Cu K-EXAFS of Bi 2 Sr 1.5 Ca 1.5 Cu 2 O 8+δ using a full multiple scattering analysis in a cluster with diameter d∼ 7.6 A. The layered structure has numerous quasi one-dimensional structural elements which give rise to significant multiple scattering contributions in the EXAFS. We confirm the Sr/Ca ratio of the sample is 1:1, and one Ca atom is located close to a nominal Sr-site. At 40 K the dimpling angle in the CuO 2 -plane is found to be ≤ 3.5 . (author)

Quenched Magnon excitations by oxygen sublattice reconstruction in (SrCuO2)n/(SrTiO3)2 superlattices.

Science.gov (United States)

Dantz, M; Pelliciari, J; Samal, D; Bisogni, V; Huang, Y; Olalde-Velasco, P; Strocov, V N; Koster, G; Schmitt, T

2016-09-12

The recently discovered structural reconstruction in the cuprate superlattice (SrCuO2)n/(SrTiO3)2 has been investigated across the critical value of n = 5 using resonant inelastic x-ray scattering (RIXS). We find that at the critical value of n, the cuprate layer remains largely in the bulk-like two-dimensional structure with a minority of Cu plaquettes being reconstructed. The partial reconstruction leads to quenching of the magnons starting at the Γ-point due to the minority plaquettes acting as scattering points. Although comparable in relative abundance, the doped charge impurities in electron-doped cuprate superconductors do not show this quenching of magnetic excitations.

Interfacial engineering of CuO nanorod/ZnO nanowire hybrid nanostructure photoanode in dye-sensitized solar cell

Science.gov (United States)

Kilic, Bayram; Turkdogan, Sunay; Astam, Aykut; Baran, Sümeyra Seniha; Asgin, Mansur; Gur, Emre; Kocak, Yusuf

2018-01-01

Developing efficient and cost-effective photoanode plays a vital role determining the photocurrent and photovoltage in dye-sensitized solar cells (DSSCs). Here, we demonstrate DSSCs that achieve relatively high power conversion efficiencies (PCEs) by using one-dimensional (1D) zinc oxide (ZnO) nanowires and copper (II) oxide (CuO) nanorods hybrid nanostructures. CuO nanorod-based thin films were prepared by hydrothermal method and used as a blocking layer on top of the ZnO nanowires' layer. The use of 1D ZnO nanowire/CuO nanorod hybrid nanostructures led to an exceptionally high photovoltaic performance of DSSCs with a remarkably high open-circuit voltage (0.764 V), short current density (14.76 mA/cm2 under AM1.5G conditions), and relatively high solar to power conversion efficiency (6.18%) . The enhancement of the solar to power conversion efficiency can be explained in terms of the lag effect of the interfacial recombination dynamics of CuO nanorod-blocking layer on ZnO nanowires. This work shows more economically feasible method to bring down the cost of the nano-hybrid cells and promises for the growth of other important materials to further enhance the solar to power conversion efficiency.

Efficient hole-transporting layer MoO{sub 3}:CuI deposited by co-evaporation in organic photovoltaic cells

Energy Technology Data Exchange (ETDEWEB)

Barkat, L.; Khelil, A. [Universite d' Oran 1 - Ahmed Ben Bella, LPCM2E, Oran (Algeria); Hssein, M. [Universite de Nantes, Institut des Materiaux Jean Rouxel (IMN), CNRS, UMR 6502, Nantes (France); Laboratoire Optoelectronique et Physico-chimie des Materiaux, Universite Ibn Tofail, Faculte des Sciences, Kenitra (Morocco); El Jouad, Z. [Laboratoire Optoelectronique et Physico-chimie des Materiaux, Universite Ibn Tofail, Faculte des Sciences, Kenitra (Morocco); Universite de Nantes, MOLTECH-Anjou, CNRS, UMR 6200, Nantes (France); Cattin, L.; Louarn, G.; Stephant, N. [Universite de Nantes, Institut des Materiaux Jean Rouxel (IMN), CNRS, UMR 6502, Nantes (France); Ghamnia, M. [Universite d' Oran 1 - Ahmed Ben Bella, Laboratoire des Sciences de la Matiere Condensee (LSMC), Oran (Algeria); Addou, M. [Laboratoire Optoelectronique et Physico-chimie des Materiaux, Universite Ibn Tofail, Faculte des Sciences, Kenitra (Morocco); Morsli, M. [Universite de Nantes, Faculte des Sciences et des Techniques, Nantes (France); Bernede, J.C. [Universite de Nantes, MOLTECH-Anjou, CNRS, UMR 6200, Nantes (France)

2017-01-15

In order to improve hole collection at the interface anode/electron donor in organic photovoltaic cells, it is necessary to insert a hole-transporting layer. CuI was shown to be a very efficient hole-transporting layer. However, its tendency to be quite rough tends to induce leakage currents and it is necessary to use a very slow deposition rate for CuI to avoid such negative effect. Herein, we show that the co-deposition of MoO{sub 3} and CuI avoids this difficulty and allows deposition of a homogeneous efficient hole-collecting layer at an acceptable deposition rate. Via an XPS study, we show that blending MoO{sub 3}:CuI improves the hole collection efficiency through an increase of the gap state density. This increase is due to the formation of Mo{sup 5+} following interaction between MoO{sub 3} and CuI. Not only does the co-evaporation process allow for decreasing significantly the deposition time of the hole-transporting layer, but also it increases the efficiency of the device based on the planar heterojunction, CuPc/C{sub 60}. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

In situ codoping of a CuO absorber layer with aluminum and titanium: the impact of codoping and interface engineering on the performance of a CuO-based heterojunction solar cell

Science.gov (United States)

Masudy-Panah, Saeid; Radhakrishnan, K.; Ru, Tan Hui; Yi, Ren; Wong, Ten It; Dalapati, Goutam Kumar

2016-09-01

Aluminum-doped cupric oxide (CuO:Al) was prepared via an out-diffusion process of Al from an Al-coated substrate into the deposited CuO thin film upon thermal treatment. The effect of the annealing temperature on the structural and optical properties of CuO:Al was investigated in detail. The influence of Al incorporation on the photovoltaic properties was then investigated by preparing a p-CuO:Al/n-Si heterojunction solar cell. A significant improvement in the performance of the solar cell was achieved by controlling the out-diffusion of Al. A novel in situ method to co-dope CuO with Al and titanium (Ti) has been proposed to demonstrate CuO-based solar cells with the front surface field (FSF) design. The FSF design was created by depositing a CuO:Al layer followed by a Ti-doped CuO (CuO:Ti) layer. This is the first successful experimental demonstration of the codoping of a CuO thin film and CuO thin film solar cells with the FSF design. The open circuit voltage (V oc), short circuit current density (J sc) and fill factor (FF) of the fabricated solar cells were significantly higher for the FSF device compared to devices without FSF. The FF of this device improved by 68% through the FSF design and a record efficiency ɳ of 2% was achieved. The improvement of the solar cell properties is mainly attributed to the reduction of surface recombination, which influences the charge carrier collection.

A novel nonenzymatic amperometric hydrogen peroxide sensor based on CuO@Cu2O nanowires embedded into poly(vinyl alcohol).

Science.gov (United States)

Chirizzi, Daniela; Guascito, Maria Rachele; Filippo, Emanuela; Tepore, Antonio

2016-01-15

A new, very simple, rapid and inexpensive nonenzymatic amperometric sensor for hydrogen peroxide (H2O2) detection is proposed. It is based on the immobilization of cupric/cuprous oxide core shell nanowires (CuO@Cu2O-NWs) in a poly(vinyl alcohol) (PVA) matrix directly drop casted on a glassy carbon electrode surface to make a CuO@Cu2O core shell like NWs PVA embedded (CuO@Cu2O-NWs/PVA) sensor. CuO nanowires with mean diameters of 120-170nm and length in the range 2-5μm were grown by a simple catalyst-free thermal oxidation process based on resistive heating of pure copper wires at ambient conditions. The oxidation process of the copper wire surface led to the formation of a three layered structure: a thick Cu2O bottom layer, a CuO thin intermediate layer and CuO nanowires. CuO nanowires were carefully scratched from Cu2O layer with a sharp knife, dispersed into ethanol and sonicated. Then, the NWs were embedded in PVA matrix. The morphological and spectroscopic characterization of synthesized CuO-NWs and CuO@Cu2O-NWs/PVA were performed by transmission electron microscopy (TEM), selected area diffraction pattern (SAD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. Moreover a complete electrochemical characterization of these new CuO@Cu2O-NWs/PVA modified glassy carbon electrodes was performed by Cyclic Voltammetry (CV) and Cronoamperometry (CA) in phosphate buffer (pH=7; I=0.2) to investigate the sensing properties of this material against H2O2. The electrochemical performances of proposed sensors as high sensitivity, fast response, reproducibility and selectivity make them suitable for the quantitative determination of hydrogen peroxide substrate in batch analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

A new Pb{sup II}(ethylenediaminetetraacetate) coordination polymer with a two-dimensional layer structure

Energy Technology Data Exchange (ETDEWEB)

Zhao, D., E-mail: iamzd@hpu.edu.cn; Zhang, R. H.; Li, F. F. [Henan Polytechnic University, Department of Physics and Chemistry (China)

2016-12-15

A new Pb{sup II}−edta{sup 4–} coordination polymer, Pb{sub 2}(edta)(H{sub 2}O){sub 0.76} (edta{sup 4–} = ethylenediaminetetraacetate) was synthesized under hydrothermal condition. Single crystal X-ray analysis reveals that it represents a novel two-dimensional (2D) Pb{sup 2+}–edta{sup 4–} layer structure with a (4,8{sup 2})-topology. Each edta{sup 4–} ligand employs its four carboxylate O and two N atoms to chelate one Pb{sup II} atom (hexa-coordinated) and connects five Pb{sup II} atoms (ennea-coordinated) via its four carboxylate groups to form 2D layer framework. Adjacent layers are packed into the overall structure through vander Waals interactions.

Dimensional crossover of electron weak localization in ZnO/TiO{sub x} stacked layers grown by atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Saha, D., E-mail: sahaphys@gmail.com, E-mail: pmisra@rrcat.gov.in; Misra, P., E-mail: sahaphys@gmail.com, E-mail: pmisra@rrcat.gov.in; Joshi, M. P.; Kukreja, L. M. [Laser Materials Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India); Bhartiya, S. [Laser Materials Development & Devices Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India); Gupta, M. [UGC-DAE Consortium for Scientific Research, Indore 452 017 (India)

2016-01-25

We report on the dimensional crossover of electron weak localization in ZnO/TiO{sub x} stacked layers having well-defined and spatially-localized Ti dopant profiles along film thickness. These films were grown by in situ incorporation of sub-monolayer TiO{sub x} on the growing ZnO film surface and subsequent overgrowth of thin conducting ZnO spacer layer using atomic layer deposition. Film thickness was varied in the range of ∼6–65 nm by vertically stacking different numbers (n = 1–7) of ZnO/TiO{sub x} layers of nearly identical dopant-profiles. The evolution of zero-field sheet resistance (R{sub ◻}) versus temperature with decreasing film thickness showed a metal to insulator transition. On the metallic side of the metal-insulator transition, R{sub ◻}(T) and magnetoresistance data were found to be well corroborated with the theoretical framework of electron weak localization in the diffusive transport regime. The temperature dependence of both R{sub ◻} and inelastic scattering length provided strong evidence for a smooth crossover from 2D to 3D weak localization behaviour. Results of this study provide deeper insight into the electron transport in low-dimensional n-type ZnO/TiO{sub x} stacked layers which have potential applications in the field of transparent oxide electronics.

Ultra-fine CuO Nanoparticles Embedded in Three-dimensional Graphene Network Nano-structure for High-performance Flexible Supercapacitors

International Nuclear Information System (INIS)

Li, Yanrong; Wang, Xue; Yang, Qi; Javed, Muhammad Sufyan; Liu, Qipeng; Xu, Weina; Hu, Chenguo; Wei, Dapeng

2017-01-01

High conductivity, large specific surface area and excellent performance redox materials are urgently desired for improving electrochemical energy storage. However, with single redox material it is hard to achieve these properties. Herein, we develop ultra-fine CuO nanoparticles embedded in three-dimensional graphene network grown on carbon cloth (CuO/3DGN/CC) to construct a novel electrode material with advantages of high conductivity, large specific area and excellent redox activity for supercapacitor application. The CuO/3DGN/CC with different CuO mass ratios are utilized to fabricate supercapacitors and the optimized mass loading achieves the high areal capacitance of 2787 mF cm"−"2 and specific capacitance of 1539.8 F g"−"1 at current density of 6 mA cm"−"2 with good stability. In addition, a high-flexible solid-state symmetric supercapacitor is also fabricated by using this CuO/3DGN/CC composite. The device shows excellent electrochemical performance even at various bending angles indicating a promising application for wearable electronic devices, and two devices with area 2 × 4 cm"2 in series can light nine light emitting diodes for more than 3 minutes.

Stabilization of the O p2x2 phase on Cu(001) sheltered by wrinkled BN over-layer

Science.gov (United States)

Kim, Yong-Sung; Ma, Chuanxu; Li, An-Ping; Yoon, Mina

The 2 √3x √3R45°phase of oxygen (O) on the Cu(001) surface has been observed in scanning tunneling microscopy (STM) measurements. Although the p2x2 phase of O on the Cu(001) surface has been proposed theoretically to be the most stable in O-lean conditions, it has not been observed in experiments for a long time. Recently, the O p2x2 phase has been found in STM on the Cu(001) surface with an overlying BN monolayer. In this theoretical study, we investigate what the role of BN over-layer is to stabilize the O p2x2 phase on the Cu(001) surface. The BN over-layer is lattice-matched with the Cu(001) surface and the BN mono-layer sheet is periodically wrinkled along the BN arm-chair direction and along the [100] or [010] direction on the Cu(001) surface. The interlayer space between the Cu(001) surface and the bulge of the wrinkled BN sheet is found to play as a preferential shelter for O to be adsorbed, and the boundary of the BN inner wall along the [010] or [100] direction makes the p2x2 phase more favorable against the 45°-tilted 2 √3x √3R45°phase of O on the Cu(001) surface. This was supported by Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility, and the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, maaged by UT-Battelle, LLC, for the U. S. DOE.

Reversible transition between bipolar and unipolar resistive switching in Cu2O/Ga2O3 binary oxide stacked layer

Directory of Open Access Journals (Sweden)

Y. S. Zhi

2016-01-01

Full Text Available Both unipolar resistive switching (URS and bipolar resistive switching (BRS behaviors are observed in Cu2O/Ga2O3 stacked layer. The conversion between BRS and URS is controllable and reversible. The switching operations in BRS mode requires smaller voltage than that in the URS mode. The oxygen vacancies closed to the Cu2O/Ga2O3 interface contributes to the BRS, and the bias-controlling filament formation/rupture in depletion layer is considered to contribute to the URS. The URS happens only in the negative voltage part due to the nature of directionality of the p-n junction. The process reported here can be developed to design memory device.

Photoelectric properties and charge dynamics in ZnO nanowires/Cu{sub 4}Bi{sub 4}S{sub 9} and ZnO nanowires/In{sub 2}O{sub 3}/Cu{sub 4}Bi{sub 4}S{sub 9} heterostructures

Energy Technology Data Exchange (ETDEWEB)

Liu, Xiangyang, E-mail: lxy081276@126.com, E-mail: yzgu@henu.edu.cn; Wang, Shun; Gu, Yuzong, E-mail: lxy081276@126.com, E-mail: yzgu@henu.edu.cn [Institue of Microsystems Physics and School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Zhang, Jingwei; Zhang, Jiwei [The Key Laboratory for Special Functional Materials of MOE, Henan University, Kaifeng 475004 (China)

2014-12-28

ZnO nanowires arrays were preformed in a horizontal double-tube system. Two types of heterostructures (ZnO nanowires/Cu{sub 4}Bi{sub 4}S{sub 9} and ZnO nanowires/In{sub 2}O{sub 3}/Cu{sub 4}Bi{sub 4}S{sub 9}) and three-dimensional solar cells were fabricated with ZnO nanowires arrays as working electrode, In{sub 2}O{sub 3} as buffer layer, and Cu{sub 4}Bi{sub 4}S{sub 9} as inorganic dye and hole collector. It is suggested that two types of heterostructures have the similar absorption properties with single Cu{sub 4}Bi{sub 4}S{sub 9}. However, the results of steady state and electric field-induced surface photovoltage indicate that ZnO nanowires/In{sub 2}O{sub 3}/Cu{sub 4}Bi{sub 4}S{sub 9} exhibits the higher photovoltaic response than ZnO nanowires/Cu{sub 4}Bi{sub 4}S{sub 9}. Using the transient surface photovoltage spectroscopy, we further studied the separation and transport mechanism of photogenerated charges. Furthermore, Cu{sub 4}Bi{sub 4}S{sub 9}/In{sub 2}O{sub 3}/ZnO cells presents the better performance than Cu{sub 4}Bi{sub 4}S{sub 9}/ZnO cells and the highest efficiencies are about 6.4% and 5.2%, respectively. It is suggested that direct paths, interface barrier, built-in electric field, and double energy level matchings between conduction bands (Cu{sub 4}Bi{sub 4}S{sub 9} and In{sub 2}O{sub 3}, In{sub 2}O{sub 3} and ZnO) have obvious effect on the separation of photogenerated charges. Then we discussed the synthetic action on the charge dynamics from these factors.

Controlled Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers

Science.gov (United States)

2016-06-15

AFRL-AFOSR-JP-TR-2016-0071 Controlled Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers Cheolmin Park YONSEI UNIVERSITY...Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-14-1-4054 5c.  PROGRAM ELEMENT...prospects for a variety of emerging applications in a broad range of fields, such as electronics, energy conversion and storage, catalysis and polymer

Two-Dimensional Electron Gas at SrTiO3-Based Oxide Heterostructures via Atomic Layer Deposition

Directory of Open Access Journals (Sweden)

Sang Woon Lee

2016-01-01

Full Text Available Two-dimensional electron gas (2DEG at an oxide interface has been attracting considerable attention for physics research and nanoelectronic applications. Early studies reported the formation of 2DEG at semiconductor interfaces (e.g., AlGaAs/GaAs heterostructures with interesting electrical properties such as high electron mobility. Besides 2DEG formation at semiconductor junctions, 2DEG was realized at the interface of an oxide heterostructure such as the LaAlO3/SrTiO3 (LAO/STO heterojunction. The origin of 2DEG was attributed to the well-known “polar catastrophe” mechanism in oxide heterostructures, which consist of an epitaxial LAO layer on a single crystalline STO substrate among proposed mechanisms. Recently, it was reported that the creation of 2DEG was achieved using the atomic layer deposition (ALD technique, which opens new functionality of ALD in emerging nanoelectronics. This review is focused on the origin of 2DEG at oxide heterostructures using the ALD process. In particular, it addresses the origin of 2DEG at oxide interfaces based on an alternative mechanism (i.e., oxygen vacancies.

Surface studies by low energy ion beams: Cu/Ru(0001) and Cu/O/Ru(0001)

Energy Technology Data Exchange (ETDEWEB)

Shen, Y.G.; O`Connor, D.J.; MacDonald, R.J. [Newcastle Univ., NSW (Australia). Dept. of Physics; Wandelt, H. [Institut fur Physikalische und Theoretische Chemie der Universitat Bonn, Bonn (Germany).; Zee, H. van [Eindhoven University of Technology, Eindhoven (Netherlands) Dept. of Physics

1993-12-31

The surface structure of Cu on Ru(OOO1) has been studied by low energy Li{sup +} ion scattering. It was found that Cu forms pseudomorphic islands for two layers. The effects of Cu on an O-precovered RU(OOO1) surface has also been investigated using keV He{sup +} ions. The results show that during the deposition of Cu, O is displaced from the Ru surface and migrated onto the top of the surface of the growing overlayer. The floated out O has been tested, showing a disordered overlayer. 5 refs., 3 figs.

Surface studies by low energy ion beams: Cu/Ru(0001) and Cu/O/Ru(0001)

Energy Technology Data Exchange (ETDEWEB)

Shen, Y G; O` Connor, D J; MacDonald, R J [Newcastle Univ., NSW (Australia). Dept. of Physics; Wandelt, H [Institut fur Physikalische und Theoretische Chemie der Universitat Bonn, Bonn (Germany).; Zee, H van [Eindhoven University of Technology, Eindhoven (Netherlands) Dept. of Physics

1994-12-31

The surface structure of Cu on Ru(OOO1) has been studied by low energy Li{sup +} ion scattering. It was found that Cu forms pseudomorphic islands for two layers. The effects of Cu on an O-precovered RU(OOO1) surface has also been investigated using keV He{sup +} ions. The results show that during the deposition of Cu, O is displaced from the Ru surface and migrated onto the top of the surface of the growing overlayer. The floated out O has been tested, showing a disordered overlayer. 5 refs., 3 figs.

Materials science and integration bases for fabrication of (BaxSr1-x)TiO3 thin film capacitors with layered Cu-based electrodes

Science.gov (United States)

Fan, W.; Kabius, B.; Hiller, J. M.; Saha, S.; Carlisle, J. A.; Auciello, O.; Chang, R. P. H.; Ramesh, R.

2003-11-01

The synthesis and fundamental material properties of layered TiAl/Cu/Ta electrodes were investigated to achieve the integration of Cu electrodes with high-dielectric constant (κ) oxide thin films for application to the fabrication of high-frequency devices. The Ta layer is an excellent diffusion barrier to inhibit deleterious Cu diffusion into the Si substrate, while the TiAl layer provides an excellent barrier against oxygen diffusion into the Cu layer to inhibit Cu oxidation during the growth of the high-κ layer in an oxygen atmosphere. Polycrystalline (BaxSr1-x)TiO3 (BST) thin films were grown on the Cu-based bottom electrode by rf magnetron sputtering at temperatures in the range 400-600 °C in oxygen, to investigate the performance of BST/Cu-based capacitors. Characterization of the Cu-based layered structure using surface analytical methods showed that two amorphous oxide layers were formed on both sides of the TiAl barrier, such that the oxide layer on the free surface of the TiAl layer correlates with TiAlOx, while the oxide layer at the TiAl/Cu interface is an Al2O3-rich layer. This double amorphous barrier layer structure effectively prevents oxygen penetration towards the underlying Cu and Ta layers. The TiAlOx interfacial layer, which has a relatively low dielectric constant compared with BST, reduced the total capacitance of the BST thin film capacitors. In addition, the layered electrode-oxide interface roughening observed during the growth of BST films at high temperature, due to copper grain growth, resulted in large dielectric loss on the fabricated BST capacitors. These problems were solved by growing the BST layer at 450 °C followed by a rapid thermal annealing at 700 °C. This process significantly reduced the thickness of the TiAlOx layer and interface roughness resulting in BST capacitors exhibiting properties suitable for the fabrication of high-performance high-frequency devices. In summary, relatively high dielectric constant (280), low

Aspects of the SrO-CuO-TiO₂ Ternary System Related to the Deposition of SrTiO₃ and Copper-Doped SrTiO₃ Thin-Film Buffer Layers

Energy Technology Data Exchange (ETDEWEB)

Ayala, Alicia [Univ. of New Mexico, Albuquerque, NM (United States)

2004-12-20

YBa₂Cu₃O_27-δ (YBCO) coated conductors are promising materials for large-scale superconductivity applications. One version of a YBCO coated conductor is based on ion beam assisted deposition (IBAD) of magnesium oxide (MgO) onto polycrystalline metal substrates. SrTiO₃ (STO) is often deposited by physical vapor deposition (PVD) methods as a buffer layer between the YBCO and IBAD MgO due to its chemical stability and lattice mismatch of only ~1.5% with YBCO. In this work, some aspects of the stability of STO with respect to copper (Cu) and chemical solution deposition of STO on IBAD MgO templates were examined. Solubility limits of Cu in STO were established by processing Cu-doped STO powders by conventional bulk preparation techniques. The maximum solubility of Cu in STO was ~1% as determined by transmission electron microscopy (TEM) and Rietveld refinements of x-ray diffraction (XRD) data. XRD analysis, performed in collaboration with NIST, on powder compositions on the STO/SrCuO₂ tie line did not identify any ternary phases. SrCu_0.10T_0.90O_y buffer layers were prepared by pulsed laser deposition (PLD) and CSD on IBAD MgO flexible metallic textured tapes. TEM analysis of a ~100 nm thick SrCu_0.10Ti_0.90O_y buffer layer deposited by PLD showed a smooth Cu-doped STO/MgO interface. A ~600 nm thick YBCO film, deposited onto the SrCu_0.10Ti_0.90O_y buffer by PLD, exhibited a T_c of 87 K and critical current density (J_c) of ~1 MA/cm². STO and Cu-doped STO thin films by CSD were ~30 nm thick. The in plane alignment (FWHM) after deposition of the STO improved by ~1° while it degraded by ~2° with the SrCu_0.05TiO_y buffer. YBCO was deposited by PLD on the STO and SrCu_0.05TiO_y buffers. The in plane alignment (FWHM) of the YBCO with the STO buffer layer

Smooth surfaces in very thin GdBa2Cu3O7−δ films for application in superconducting tunnel junctions

International Nuclear Information System (INIS)

Navarro, H.; Sirena, M.; Kim, Jeehoon; Haberkorn, N.

2015-01-01

Highlights: • A detailed study of the morphological properties of GdBa 2 Cu 3 O 7−δ thin films was realized. • The inclusion of a very thin SrTiO 3 buffer layer modifies the surface of the SrTiO 3 substrates. • The inclusion of the buffer layer suppress the three dimensional nucleation in the GdBa 2 Cu 3 O 7−δ film. • GdBa 2 Cu 3 O 7−δ films with large areas free of topological defects and T c close to liquid nitrogen can be obtained. - Abstract: This paper provides a systematic analysis of the morphology and the superconducting critical temperature obtained in very thin GdBa 2 Cu 3 O 7−δ films grown on (0 0 1) SrTiO 3 substrates by DC sputtering. We find that the use of a very thin SrTiO 3 buffer layer (≈2 nm) modify the nucleation of GdBa 2 Cu 3 O 7−δ on the surface of the substrate reducing the formation of 3 dimensional clusters. Our results demonstrate that 16 nm thick GdBa 2 Cu 3 O 7−δ films with an average root-mean-square (RMS) smaller than 1 nm and large surface areas (up 10 μm 2 ) free of 3 dimensional topological defects can be obtained. In films thinner than 24 nm the onset (zero resistance) of superconducting transition of the films is reduced, being close to liquid nitrogen. This fact can be associated with stress reducing the orthorhombicity and slightly drop in oxygen stoichiometry

Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13}: A new telluro-phosphate with S=1/2 Heisenberg chain

Energy Technology Data Exchange (ETDEWEB)

Xia, Mingjun [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Shen, Shipeng; Lu, Jun; Sun, Young [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Li, R.K., E-mail: rkli@mail.ipc.ac.cn [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

2015-10-15

A new telluro-phosphate compound Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13} with S=1/2 Heisenberg chain has been successfully synthesized by solid state reaction and grown by flux method. Single crystal X-ray diffraction reveals that Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13} crystallizes into a monoclinic space group C2/c and cell parameters of a=17.647(3) Å, b=7.255(2) Å, c=9.191(2) Å and β=100.16 (3)°. In the structure of Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13}, one dimensional [CuTePO{sub 7}]{sup 3−} chains are formed by tetrahedral PO{sub 4} and trigonal bi-pyramidal TeO{sub 4} joining square planar CuO{sub 4} groups. Those [CuTePO{sub 7}]{sup 3−} chains are inter-connected by sharing one oxygen atom from the TeO{sub 4} group to form two dimensional layers. Magnetic susceptibility and specific heat measurements confirm that the title compound is a model one dimensional Heisenberg antiferromagnetic chain system. - Graphical abstract: Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13}, containing (CuTePO{sub 7}){sup 3−} chains formed by PO{sub 4} and TeO{sub 4} joining CuO{sub 4} groups, shows typical 1D Heisenberg antiferromagnetic chain model behavior as confirmed by magnetic measurements. - Highlights: • New telluro-phosphate Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13} has been grown. • It features layered structure composed of [CuTePO{sub 7}]{sup 3−} chains and TeO{sub 4} groups. • It shows the Heisenberg antiferromagnetic chain behavior. • It is transparent in the range of 1000–2500 nm with a UV absorption edge of 393 nm.

Interdiffusion studies on high-Tc superconducting YBa2Cu3O7-δ thin films on Si(111) with a NiSi2/ZrO2 buffer layer

DEFF Research Database (Denmark)

Aarnink, W.A.M.; Blank, D.H.A.; Adelerhof, D.J.

1991-01-01

Interdiffusion studies on high-T(c) superconducting YBa2Cu3O7-delta thin films with thickness in the range of 2000-3000 angstrom, on a Si(111) substrate with a buffer layer have been performed. The buffer layer consists of a 400 angstrom thick epitaxial NiSi2 layer covered with 1200 angstrom...... of polycrystalline ZrO2. YBa2Cu3O7-delta films were prepared using laser ablation. The YBa2Cu3O7-delta films on the Si/NiSi2/ZrO2 substrates are of good quality; their critical temperatures T(c,zero) and T(c,onset) have typical values of 85 and 89 K, respectively. The critical current density j(c) at 77 K equaled 4...... x 10(4) A/cm2. With X-ray analysis (XRD), only c-axis orientation has been observed. The interdiffusion studies, using Rutherford backscattering spectrometry (RBS) and scanning Auger microscopy (SAM) show that the ZrO2 buffer layer prevents severe Si diffusion to the YBa2Cu3O7-delta layer, the Si...

Evidence for the quasi-two dimensional behavior of the vortex structure in Bi2Sr2CaCu2O8 single crystals

International Nuclear Information System (INIS)

Pastoriza, H.; Arribere, A.; Goffman, M.F.; Cruz, F. de la; Mitzi, D.B.; Kapitulnik, A.

1994-01-01

AC susceptibility and dc magnetization measurements on Bi 2 Sr 2 CaCu 2 O 8 (BSCCO) single crystals in a wide range of temperatures clearly show that below the dc irreversibility line the vortex system loss the long range order in the c direction. The susceptibility data taken at 7 Hz show the different nature of two dissipation peaks: One related to the interplane currents at temperatures well below the dc irreversibility line and the other associated with the intraplane ones at temperatures above that line. In this sense the irreversibility line corresponds to the temperature where quasi-two dimensional vortices are depinned. (orig.)

Metal insulator semiconductor solar cell devices based on a Cu2O substrate utilizing h-BN as an insulating and passivating layer

International Nuclear Information System (INIS)

Ergen, Onur; Gibb, Ashley; Vazquez-Mena, Oscar; Zettl, Alex; Regan, William Raymond

2015-01-01

We demonstrate cuprous oxide (Cu 2 O) based metal insulator semiconductor Schottky (MIS-Schottky) solar cells with efficiency exceeding 3%. A unique direct growth technique is employed in the fabrication, and hexagonal boron nitride (h-BN) serves simultaneously as a passivation and insulation layer on the active Cu 2 O layer. The devices are the most efficient of any Cu 2 O based MIS-Schottky solar cells reported to date

Synthesis, crystal structure and charge-distribution validation of β-Na4Cu(MoO43 adopting the alluadite structure-type

Directory of Open Access Journals (Sweden)

Wassim Dridi

2016-08-01

Full Text Available Single crystals of a new variety of tetrasodium copper(II tris[molybdate(VI], Na4Cu(MoO43, have been synthesized by solid-state reactions and characterized by single-crystal X-ray diffraction. This alluaudite structure-type is characterized by the presence of infinite layers of composition (Cu/Na2Mo3O14 parallel to the (100 plane, which are linked by MoO4 tetrahedra, forming a three-dimensional framework containing two types of hexagonal channels in which Na+ cations reside. The Cu2+ and Na2+ cations are located at the same general site with occupancies of 0.5. All atoms are on general positions except for one Mo, two Na (site symmetry 2 and another Na (site symmetry -1 atom. One O atom is split into two separate positions with occupancies of 0.5. The title compound is isotypic with Na5Sc(MoO44 and Na3In2As3O12. The structure model is supported by bond-valence-sum (BVS and charge-distribution CHARDI methods. β-Na4Cu(MoO43 is compared and discussed with the K4Cu(MoO43 and α-Na4Cu(MoO43 structures.

Three-dimensionality of field-induced magnetism in a high-temperature superconductor

DEFF Research Database (Denmark)

Lake, B.; Lefmann, K.; Christensen, N.B.

2005-01-01

Many physical properties of high-temperature superconductors are two-dimensional phenomena derived from their square-planar CuO(2) building blocks. This is especially true of the magnetism from the copper ions. As mobile charge carriers enter the CuO(2) layers, the antiferromagnetism of the parent...

Diffusion barrier performance of novel Ti/TaN double layers for Cu metallization

International Nuclear Information System (INIS)

Zhou, Y.M.; He, M.Z.; Xie, Z.

2014-01-01

Highlights: • Novel Ti/TaN double layers offering good stability as a barrier against Cu metallization have been made achievable by annealing in vacuum. • The Ti/TaN double layers improved the adhesion with Cu thin films and showed good diffusion barrier between Cu and SiO 2 /Si up to the annealing condition. • The failure mechanism of Ti/TaN bi-layer is similar with the Cu/TaN/Si metallization system in which Cu atoms diffuse through the grain boundary of barrier and react with silicon to form Cu 3 Si. - Abstract: Novel Ti/TaN double layers offering good stability as a barrier against Cu metallization have been made achievable by annealing in vacuum better than 1 × 10 −3 Pa. Ti/TaN double layers were formed on SiO 2 /Si substrates by DC magnetron sputtering and then the properties of Cu/Ti/TaN/SiO 2 /Si film stacks were studied. It was found that the Ti/TaN double layers provide good diffusion barrier between Cu and SiO 2 /Si up to 750 °C for 30 min. The XRD, Auger and EDS results show that the Cu–Si compounds like Cu 3 Si were formed by Cu diffusion through Ti/TaN barrier for the 800 °C annealed samples. It seems that the improved diffusion barrier property of Cu/Ti/TaN/SiO 2 /Si stack is due to the diffusion of nitrogen along the grain boundaries in Ti layer, which would decrease the defects in Ti film and block the diffusion path for Cu diffusion with increasing annealing temperature. The failure mechanism of Ti/TaN bi-layer is similar to the Cu/TaN/Si metallization system in which Cu atoms diffuse through the grain boundary of barrier and react with silicon to form Cu 3 Si

Two-dimensional optical simulation on a visible ray passing through inter-metal dielectric layers of CMOS image sensor device

International Nuclear Information System (INIS)

Lee, Wan-Gyu; Kim, Jun-Seok; Kim, Hee-Jeen; Kim, Sang-Young; Hwang, Sung-Bo; Lee, Jeong-Gun

2005-01-01

Two-dimensional optical simulation has been performed for investigating light propagation through a micro lens and inter-metal dielectric (IMD) layers in an Al and Cu back-end of line (BEOL) onto a Si photodiode, and its effects on the wave power, as well as optical carriers generated by a visible ray in the silicon substrate area, i.e. photodiode of a CMOS image sensor pixel. The number of optically generated carriers in an Al-BEOL has been compared to a Cu-BEOL. It is shown that more optical carriers are generated in the Cu-BEOL for the red color because a higher permittivity dielectric material like SiC is used in the Cu-BEOL to prevent Cu from diffusing into the dielectric material, resulting in higher optical loss in the higher- permittivity dielectric layers. Thus, the optical power density arriving in the silicon substrate is higher in the Al-BEOL than in the Cu-BEOL when the wavelength is blue (470 nm) or green (550 nm) in the visible ray spectrum. In conclusion, the structure of a Cu-BEOL in a CMOS image sensor has to be optimized for generating more optical carriers through lower-permittivity IMD materials or by reducing the permittivity difference between SiC (or SiN) and IMD materials, without deteriorating the capability as a barrier to Cu diffusion.

Theoretical investigation of the Fermi surfaces of La2-xSrxCuO4 and YBa2Cu3O7

International Nuclear Information System (INIS)

Antonov, V.N.; Antonov, Vl.N.; Bar'yakhtar, V.G.; Baglyuk, A.I.; Maksimov, E.G.; Nemoshkalenko, V.V.; Perlov, A.Ya.; Savrasov, S.Yu.; Uspenskii, Yu.A.

1989-01-01

A theoretical investigation is made of the shape of the Fermi surface and of the constant-energy surfaces near the Fermi energy of the La 2-x Sr x CuO 4 and YBa 2 Cu 3 O 7 oxides by a self-consistent linear muffin-tin orbital method in the atomic sphere approximation (OMTO-ASA). It is shown that the Fermi surfaces of these compounds are strongly two-dimensional. The Fermi surface of La 2-x Sr x CuO 4 is a corrugated rounded box centered at the point Λ. The Fermi surface of YBa 2 Cu 3 O 7 consists of four sheets: an electron cushion at the point Λ and three nested hole surfaces centered at the point S. The electron cushion and one of the hole surfaces are strongly corrugated along the z direction. The theoretically calculated Fermi surfaces of La 2 CuO 4 and YBa 2 Cu 3 O 7 are compared with the experimental data on electron-positron annihilation

Two dimensional layered materials: First-principle investigation

Science.gov (United States)

Tang, Youjian

Two-dimensional layered materials have emerged as a fascinating research area due to their unique physical and chemical properties, which differ from those of their bulk counterparts. Some of these unique properties are due to carriers and transport being confined to 2 dimensions, some are due to lattice symmetry, and some arise from their large surface area, gateability, stackability, high mobility, spin transport, or optical accessibility. How to modify the electronic and magnetic properties of two-dimensional layered materials for desirable long-term applications or fundamental physics is the main focus of this thesis. We explored the methods of adsorption, intercalation, and doping as ways to modify two-dimensional layered materials, using density functional theory as the main computational methodology. Chapter 1 gives a brief review of density functional theory. Due to the difficulty of solving the many-particle Schrodinger equation, density functional theory was developed to find the ground-state properties of many-electron systems through an examination of their charge density, rather than their wavefunction. This method has great application throughout the chemical and material sciences, such as modeling nano-scale systems, analyzing electronic, mechanical, thermal, optical and magnetic properties, and predicting reaction mechanisms. Graphene and transition metal dichalcogenides are arguably the two most important two-dimensional layered materials in terms of the scope and interest of their physical properties. Thus they are the main focus of this thesis. In chapter 2, the structure and electronic properties of graphene and transition metal dichalcogenides are described. Alkali adsorption onto the surface of bulk graphite and metal intecalation into transition metal dichalcogenides -- two methods of modifying properties through the introduction of metallic atoms into layered systems -- are described in chapter 2. Chapter 3 presents a new method of tuning

Lithiation Confined in One Dimensional Nanospace of TiO2 (Anatase) Nanotube to Enhance the Lithium Storage Property of CuO Nanowires.

Science.gov (United States)

Li, Ang; Song, Huaihe; Chen, Xiaohong; Zhou, Jisheng; Ma, Zhaokun

2015-10-14

We have fabricated CuO@TiO2 nanocable arrays by a facile method involving in situ thermal oxidation of Cu foil and coating of tetrabutyl titanate solution. The structure of the nanocables has been investigated by various techniques to comfirm that the cores are mainly crystalline monoclinic CuO, and the shells are crystalline tetragonal anatase TiO2. When used as an anode material for lithium-ion batteries, the nanoconfinement effect plays an important role in improving the lithium-ion storage preformance: the lithiation will be confined in one-dimensional space of TiO2 nanotubes to limit the pulverization of CuO, and the phase interface will cause an interfacial adsorption to enrich more lithium ions at some level. Benefiting from the nanoconfinement effect and interfacial adsorption, the reversible capacity does not fade, but rather increases gradually to 725 mAh g(-1) after 400 cycles at a current density of 60 mA g(-1), superior to the theoretical capacity of CuO.

The effect of CuO chains on the local density of states in the vortex phase of YBa2Cu3O7

International Nuclear Information System (INIS)

Atkinson, W A

2009-01-01

We examine the effects of the CuO chains on the density of states in the vortex phase in YBa 2 Cu 3 O 7 , via a calculation based on the tight-binding proximity model. In this model, chain superconductivity results from single-electron hopping between the intrinsically normal chains and intrinsically superconducting CuO 2 planes. The calculations are based on self-consistent solutions of the Bogolyubov-de Gennes equations for a bilayer consisting of a single CuO 2 layer and a single CuO chain layer. We find that, in addition to the dispersing resonances found in single-layer models, there are a second set of dispersing resonances, associated with the induced gap in the chain layer. These new resonances are highly anisotropic and distort the vortex core shape.

Transparent Conductive In and Ga Doped ZnO/Cu Bi-Layered Films Deposited by DC and RF Magnetron Sputtering

International Nuclear Information System (INIS)

Moon, Hyun-Joo; Song, Young-Hwan; Oh, Jung-Hyun; Heo, Sung-Bo; Kim, Daeil

2016-01-01

In- and Ga-doped ZnO (IGZO) films were deposited on 5 nm thick Cu film buffered poly-carbonate substrates with RF magnetron sputtering and the effects of the Cu buffer layer on the optical and electrical properties of the films were investigated. The IGZO single layer films exhibited an electrical resistivity of 1.2×10"-1 Ω cm while the IGZO/Cu bi-layered films exhibited a lower resistivity of 1.6×10"-3 Ω cm. With respect to optical properties, the optical band gap of the IGZO films appeared to decrease as a result of an increasing carrier concentration due to the Cu buffer layer. In addition, the RMS roughness (8.2 nm) of the IGZO films also decreased to 6.8 nm by a Cu buffer layer in AFM observation. Although the optical transmittance in the range of visible wavelengths was deteriorated by the Cu buffer layer, the IGZO films with a 5 nm thick Cu buffer layer exhibited a higher figure of merit of 2.6×10"-4 Ω"-1 compared with the IGZO single layer films due to enhanced optoelectrical performance.

Transparent Conductive In and Ga Doped ZnO/Cu Bi-Layered Films Deposited by DC and RF Magnetron Sputtering

Energy Technology Data Exchange (ETDEWEB)

Moon, Hyun-Joo; Song, Young-Hwan; Oh, Jung-Hyun; Heo, Sung-Bo; Kim, Daeil [University of Ulsan, Ulsan (Korea, Republic of)

2016-06-15

In- and Ga-doped ZnO (IGZO) films were deposited on 5 nm thick Cu film buffered poly-carbonate substrates with RF magnetron sputtering and the effects of the Cu buffer layer on the optical and electrical properties of the films were investigated. The IGZO single layer films exhibited an electrical resistivity of 1.2×10{sup -}1 Ω cm while the IGZO/Cu bi-layered films exhibited a lower resistivity of 1.6×10{sup -}3 Ω cm. With respect to optical properties, the optical band gap of the IGZO films appeared to decrease as a result of an increasing carrier concentration due to the Cu buffer layer. In addition, the RMS roughness (8.2 nm) of the IGZO films also decreased to 6.8 nm by a Cu buffer layer in AFM observation. Although the optical transmittance in the range of visible wavelengths was deteriorated by the Cu buffer layer, the IGZO films with a 5 nm thick Cu buffer layer exhibited a higher figure of merit of 2.6×10{sup -}4 Ω{sup -}1 compared with the IGZO single layer films due to enhanced optoelectrical performance.

Transport properties of YBa2Cu3O7/PrBa2Cu3O7-superlattices

International Nuclear Information System (INIS)

El Tahan, Ayman Mohamed Moussa

2010-01-01

The understanding of the coupling between superconducting YBa 2 Cu 3 O 7 (YBCO) layers decoupled by non superconducting PrBa 2 Cu 3 O 7 (PBCO) layers in c-axis oriented superlattices was the aim of this thesis. For this purpose two conceptually different kind of transport experiments have been performed. In the first type of transport experiments the current is flowing parallel to the layers. Here the coupling is probed indirectly using magnetic vortex lines, which are penetrating the superlattice. Movement of the vortex segments in neighbouring YBCO layers is more or less coherent depending on the thickness of both the superconducting and non superconducting layers. This in-plane transport was measured either by sending an external current through bridges patterned in the superlattice or by an induced internal current. The vortex-creep activation energy U was determined by analysis of the in-plane resistive transition in an external magnetic field B oriented along the c-axis. The activation energies for two series of superlattices were investigated. In one series the thickness of the YBCO layers was constant (n Y =4 unit cells) and the number of the PBCO unit cells was varied, while in the other the number of PBCO layers was constant (n P =4) and n Y varied. The correlation length of the vortex system was determined to be 80 nm along the c-axis direction. It was found that even a single PBCO unit cell in a superlattice effectively cuts the flux lines into shorter weakly coupled segments, and the coupling of the vortex systems in neighbouring layers is negligible already for a thickness of four unit cells of the PBCO layers. A characteristic variation of the activation energy for the two series of superlattices was found, where U 0 is proportional to the YBCO thickness. A change in the variation of U 0 with the current I in the specimen was observed. The analysis of standard dc magnetization relaxation data obtained for a series superlattices revealed the

Studies on Ba(2)YNbO(6) Buffer Layers for Subsequent YBa(2)Cu(3)O(7-x) Film Growth

National Research Council Canada - National Science Library

Sathiraju, Srinivas; Barnes, Paul N; Varanasi, Chakrapani; Wheeler, Robert

2004-01-01

In this paper, we are reporting a dielectric oxide buffer Ba(2)YNbO(6) (BYNO) and its performance on various substrates for a potential buffer layer for the growth of YBa(2)Cu(3)O(7-x) (YBCO) coated conductors. Ba(2)YNbO(6...

Dimensional behavior of the anisotropy in the mixed state of a-axis oriented EuBa{sub 2}Cu{sub 3}O{sub 7}/PrBa{sub 2}Cu{sub 3}O{sub 7} and EuBa{sub 2}Cu{sub 3}O{sub 7}/SrTiO{sub 3} multilayers

Energy Technology Data Exchange (ETDEWEB)

Gonzalez, E.M.; Gonzalez, J.M. [Consejo Superior de Investigaciones Cientificas, Madrid (Spain). Inst. de Ciencia de Materiales; Gomez, A.M. [Dept. de Fisica de Materiales, Univ. Nacional de Educacion a Distancia, Madrid (Spain); Vicent, J.L. [Dept. de Fisica de Materiales, Univ. Complutense, Madrid (Spain)

1998-01-01

Thin films and superconducting/insulating multilayers of the 123-high temperature superconductor (HTS) family have been grown by a sputtering technique. The samples are grown with the so-called a-axis orientation (CuO{sub 2} planes perpendicular to the substrate). The angular dependence of the onset of dissipation (resistivity) has been measured with applied magnetic fields up to 90 kOe. In the a-axis multilayers the artificially induced anisotropy oververcomes the intrinsic anisotropy in a broad angular interval, and the insulating layers break down the dimensional scaling laws above some critical angle ({theta}{sub c}). (orig.) 8 refs.

Effect of Cu buffer layer on magnetic anisotropy of cobalt thin films deposited on MgO(001 substrate

Directory of Open Access Journals (Sweden)

Syed Sheraz Ahmad

2016-11-01

Full Text Available Cobalt thin films with 5 nm thickness were prepared on single-crystal MgO (001 substrates with different thickness Cu buffer (0 nm, 5 nm, 10 nm, 20 nm. The structure, magnetic properties and transport behaviors were investigated by employing low-energy-electron-diffraction (LEED, magneto-optical Kerr effect (MOKE and anisotropic magnetoresistance (AMR. By comparing the magnetic properties of the sample as-deposited (without Cu buffer layer one with those having the buffer Cu, we found that the magnetic anisotropy was extremely affected by the Cu buffer layer. The magnetic anisotropy of the as-deposited, without buffer layer, sample shows the uniaxial magnetic anisotropy (UMA. We found that the symmetry of the magnetic anisotropy is changed from UMA to four-fold when the thickness of the Cu buffer layer reaches to 20 nm. Meanwhile, the coercivity increased from 49 Oe (without buffer layer to 300 Oe (with 20 nm Cu buffer, in the easy axis direction, as the thickness of the buffer layer increases. Moreover, the magnitudes of various magnetic anisotropy constants were determined from torque curves on the basis of AMR results. These results support the phenomenon shown in the MOKE.

Artificial twin-layer configurations of Zn(O,S) films by radio frequency sputtering in all dry processed eco-friendly Cu(In,Ga)Se2 solar cells

Science.gov (United States)

Liu, Wei; Fan, Yu; Li, Xiaodong; Lin, Shuping; Liu, Yang; Shi, Sihan; Wang, He; Zhou, Zhiqiang; Zhang, Yi; Sun, Yun

2018-03-01

Cu(In,Ga)Se2 thin film solar cells are of great interest for research and industrial applications with their high conversion efficiencies, long-term stability and significant lifetimes. Such a solar cell of a p-n junction consists of p-type Cu(In,Ga)Se2 films as a light absorber and n-type CdS as a buffer layer, which often emerges with intrinsic ZnO. Aimed at eco-friendly fabrication protocols, a large number of strategies have been investigated to fabricate a Cd-free n-type buffer layer such as Zn(O,S) in Cu(In,Ga)Se2 solar cells. Also, if the Zn(O,S) films are prepared by coevaporation or sputtering, it will offer high compatibility with the preferred mass production. Here, we propose and optimize a dry method for Zn(O,S) deposition in a radio frequency sputtering. In particular, the strategy for the twin-layer configurations of Zn(O,S) films not only greatly improve their electrical conductance and suppress charge carrier recombination, but also avoid degradation of the Zn(O,S)/Cu(In,Ga)Se2 interfaces. Indeed, the high quality of such twin Zn(O,S) layers have been reflected in the similar conversion efficiencies of the complete solar cells as well as the large short-circuit current density, which exceeds the CdS reference device. In addition, Zn(O,S) twin layers have reduced the production time and materials by replacing the CdS/i-ZnO layers, which removes two fabrication steps in the multilayered thin film solar cells. Furthermore, the device physics for such improvements have been fully unveiled with both experimental current-voltage and capacitance-voltage spectroscopies and device simulations via wxAMPS program. Finally, the proposed twin-layer Zn(O,S)/Cu(In,Ga)Se2 interfaces account for the broadening of the depletion region of photogenerated charge carriers, which greatly suppress the carrier recombination at the space charge region, and eventually lead to the more efficient collection of charge carriers at both electrodes.

Metal insulator semiconductor solar cell devices based on a Cu{sub 2}O substrate utilizing h-BN as an insulating and passivating layer

Energy Technology Data Exchange (ETDEWEB)

Ergen, Onur; Gibb, Ashley; Vazquez-Mena, Oscar; Zettl, Alex, E-mail: azettl@berkeley.edu [Department of Physics, University of California at Berkeley, Berkeley, California 94720 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kavli Energy Nanosciences Institute at the University of California, Berkeley, and the Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Regan, William Raymond [Department of Physics, University of California at Berkeley, Berkeley, California 94720 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2015-03-09

We demonstrate cuprous oxide (Cu{sub 2}O) based metal insulator semiconductor Schottky (MIS-Schottky) solar cells with efficiency exceeding 3%. A unique direct growth technique is employed in the fabrication, and hexagonal boron nitride (h-BN) serves simultaneously as a passivation and insulation layer on the active Cu{sub 2}O layer. The devices are the most efficient of any Cu{sub 2}O based MIS-Schottky solar cells reported to date.

Cyclotron resonance study of the two-dimensional electron layers and double layers in tilted magnetic fields

Czech Academy of Sciences Publication Activity Database

Goncharuk, Natalya; Smrčka, Ludvík; Kučera, Jan

2004-01-01

Roč. 22, - (2004), s. 590-593 ISSN 1386-9477. [International Conference on Electronic Properties of Two-Dimensional Systems /15./. Nara, 14.07.2003-18.07.2003] R&D Projects: GA ČR GA202/01/0754 Institutional research plan: CEZ:AV0Z1010914 Keywords : single layer * double layer * two-dimensional electron system * cyclotron resonance Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.898, year: 2004

Spin 1/2 Delafossite Honeycomb Compound Cu5SbO6

DEFF Research Database (Denmark)

Climent-Pascual, E.; Norby, Poul; Andersen, Niels Hessel

2012-01-01

Cu5SbO6 is found to have a monoclinic, Delafossite-derived structure consisting of alternating layers of O–Cu(I)–O sticks and magnetic layers of Jahn–Teller distorted Cu(II)O6 octahedra in an edge sharing honeycomb arrangement with Sb(V)O6 octahedra. This yields the structural formula Cu(I)3Cu(II...

In Situ Synthesis of Ag@Cu2O-rGO Architecture for Strong Light-Matter Interactions

Directory of Open Access Journals (Sweden)

Shuang Guo

2018-06-01

Full Text Available Emerging opportunities based on two-dimensional (2D layered structures can utilize a variety of complex geometric architectures. Herein, we report the synthesis and properties of a 2D+0D unique ternary platform-core-shell nanostructure, termed Ag@Cu2O-rGO, where the reduced graphene oxide (rGO 2D acting as a platform is uniformly decorated by Ag@Cu2O core-shell nanoparticles. Cu2O nanoparticles occupy the defect positions on the surface of the rGO platform and restore the conjugation of the rGO structure, which contributes to the significant decrease of the ID/IG intensity ratio. The rGO platform can not only bridge the isolated nanoparticles together but also can quickly transfer the free electrons arising from the Ag core to the Cu2O shell to improve the utilization efficiency of photogenerated electrons, as is verified by high efficient photocatalytic activity of Methyl Orange (MO. The multi-interface coupling of the Ag@Cu2O-rGO platform-core-shell nanostructure leads to the decrease of the bandgap with an increase of the Cu2O shell thickness, which broadens the absorption range of the visible light spectrum.

Modulation-free bismuth-lead cuprate superconductors: BiPbSr1+xL1-xCuO6 and BiPbSr2Y1-xCaxCu2O8

International Nuclear Information System (INIS)

Manivannan, V.; Gopalakrishnan, J.; Rao, C.N.R.

1991-01-01

Modulation-free BiPbSrLCuO 6 (L=La, Pr, Nd) and BiPbSr 2 YCu 2 O 8 , which are isotypic with the n=1 and 2 members of the Bi 2 Sr 2 Ca n-1 Cu n O 2n+4 family, have been prepared and characterized. These parent compounds are nonsuperconducting, but when doped with holes by substitution chemistry give modulation-free superconducting cuprates of the general formulas BiPbSr 1+xL1-x CuO 6 and BiPbSr 2 Y 1-x Ca x Cu 2 O 8 , exhibiting maximum T c 's of 24 and 85 K, respectively. Significantly, the hole concentration at the maximum T c is 0.12 in the cuprate family with a single Cu-O layer and 0.22 in that with two Cu-O layers

Collinear Order in Frustrated Quantum Antiferromagnet on Square Lattice (CuBr)LaNb2O7

Science.gov (United States)

Oba, Noriaki; Kageyama, Hiroshi; Kitano, Taro; Yasuda, Jun; Baba, Yoichi; Nishi, Masakazu; Hirota, Kazuma; Narumi, Yasuo; Hagiwara, Masayuki; Kindo, Koichi; Saito, Takashi; Ajiro, Yoshitami; Yoshimura, Kazuyoshi

2006-11-01

Magnetic susceptibility, heat capacity, high-field magnetization and neutron diffraction measurements have been performed on a two-dimensional S = 1/2 square-lattice system (CuBr)LaNb2O7, prepared by a topotactic ion-exchange reaction of a nonmagnetic double-layered perovskite RbLaNb2O7. (CuBr)LaNb2O7 exhibits a second-order magnetic transition at 32 K, in marked contrast to a spin-singlet nature for its Cl-based counterpart (CuCl)LaNb2O7, despite nearly identical structural parameters. The magnetic structure is a novel collinear antiferromagnetic (CAF) ordering characterized by a modulation vector q = (π, 0, π) with a reduced moment of 0.6μB. Mixed ferromagnetic nearest-neighbor (J1) and antiferromagnetic second-nearest-neighbor (J2) interactions are of comparable strength (J1/kB = -35.6 K and J2/kB = 41.3 K), placing the system in a more frustrated region of the CAF phase than ever reported.

Two-dimensional Cu2Si sheet: a promising electrode material for nanoscale electronics

Science.gov (United States)

Meng Yam, Kah; Guo, Na; Zhang, Chun

2018-06-01

Building electronic devices on top of two-dimensional (2D) materials has recently become one of most interesting topics in nanoelectronics. Finding high-performance 2D electrode materials is one central issue in 2D nanoelectronics. In the current study, based on first-principles calculations, we compare the electronic and transport properties of two nanoscale devices. One device consists of two single-atom-thick planar Cu2Si electrodes, and a nickel phthalocyanine (NiPc) molecule in the middle. The other device is made of often-used graphene electrodes and a NiPc molecule. Planer Cu2Si is a new type of 2D material that was recently predicted to exist and be stable under room temperature [11]. We found that at low bias voltages, the electric current through the Cu2Si–NiPc–Cu2Si junction is about three orders higher than that through graphene–NiPc–graphene. Detailed analysis shows that the surprisingly high conductivity of Cu2Si–NiPc–Cu2Si originates from the mixing of the Cu2Si state near Fermi energy and the highest occupied molecular orbital of NiPc. These results suggest that 2D Cu2Si may be an excellent candidate for electrode materials for future nanoscale devices.

Theoretical investigation of the Fermi surface of La2-xSrxCuO4 and YBa2Cu3O7

International Nuclear Information System (INIS)

Antonov, V.N.; Antonov, V.N.; Bar'yakhtar, V.G.

1989-01-01

The theoretical investigation of both the Fermi surface (FS) form and isoenergetic surfaces near the Fermi energy of La 2-x Sr x CuO 4 and YBa 2 Cu 3 O 7 is carried out by selfconsistent LMTO/method in an atomic sphere approximation. The FS of these compounds is established to have an essential two-dimensional character. The FS La 2 CuO 4 is a corrugated rounded box centered in Γ point. The FS YBa 2 Cu 3 O 7 consists of four plates: an electron ''cushion'' in Γ point and three embeded hole surfaces centered in S point. In this case the ''cushion'' and one of the hole surfaces are vigorously corrugated along the z-direction. A comparison between both the FS calculated theoretically of La 2 CuO 4 and YBa 2 Cu 3 O 7 and experimental data on electron-positron annihilation is carried out. The electron-rate maps and numerical results of various characteristics, i.e., plate areas, mean rates, mean squares of the rates, partial densities of states for each plate of the FS YBa 2 Cu 3 O 7 are given

Microstructure of edge-type Josephson junctions with PrBa[sub 2]Cu[sub 3]O[sub 7-x] barrier layer

Energy Technology Data Exchange (ETDEWEB)

Lebedev, O I; Vasiliev, A L; Kiselev, N A [Inst. of Crystallography, Russian Academy of Sciences, Moscow (Russia); Mazo, L A; Gaponov, S V; Paveliev, D G; Strikovsky, M D [Inst. of Applied Physics, Russian Academy of Sciences, Novgorod (Russia)

1992-08-01

HREM investigations of edge Josephson junctions (EJJ) with PrBa[sub 2]Cu[sub 3]O[sub 7-x] barrier layer (PB) were performed. All layers (superconducting YBa[sub 2]Cu[sub 3]O[sub 7-x]) (Y1) and (Y2), insulating PrBa[sub 2]Cu[sub 3]O[sub 7-x] (PI) and barrier (PB) were obtained by laser ablation. The edges were formed by ion sputtering using a fotoresist mask. EJJ shows Josephson conductivity at Tc=77 K, giving j[sub c]=10[sup 4] A/cm[sup 2] at U[sub c]=50 [mu]V. Cross-sectional images show that Y1, PI and PB layers are single crystalline with the c-axis normal to the substrate surface. The Y2 layer in the regions of a multilayered structure is polycrystalline. The PB/Y1 interface is characterised by APB line boundaries; it is inclined to the substrate by 20-35deg. (orig.).

Inorganic anion-dependent assembly of zero-, one-, two- and three-dimensional Cu(II)/Ag(I) complexes under the guidance of the HSAB theory: Synthesis, structure, and magnetic property

Energy Technology Data Exchange (ETDEWEB)

Liu, Yaru; Xing, Zhiyan [School of Science, North University of China, Taiyuan, Shanxi 030051 (China); Zhang, Xiao [MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150080 (China); Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080 PR China (China); Liang, Guorui [School of Science, North University of China, Taiyuan, Shanxi 030051 (China)

2017-02-15

To systematically explore the influence of inorganic anions on building coordination complexes, five novel complexes based on 1-(benzotriazole-1-methyl)−2-propylimidazole (bpmi), [Cu(bpmi){sub 2}(Ac){sub 2}]·H{sub 2}O (1), [Cu(bpmi){sub 2}(H{sub 2}O){sub 2}]·2NO{sub 3}·2H{sub 2}O (2), [Cu(bpmi)(N{sub 3}){sub 2}] (3), [Ag(bpmi)(NO{sub 3})] (4) and [Cu{sub 3}(bpmi){sub 2}(SCN){sub 4}(DMF)] (5) (Ac{sup −}=CH{sub 3}COO{sup −}, DMF=N,N-Dimethylformamide) are synthesized through rationally introducing Cu(II) salts and Ag(I) salt with different inorganic anions. X-ray single-crystal analyses reveal that these complexes show interesting structural features from mononuclear (1), one-dimensional (2 and 3), two-dimensional (4) to three-dimensional (5) under the influence of inorganic anions with different basicities. The structural variation can be explained by the hard-soft-acid-base (HSAB) theory. Magnetic susceptibility measurement indicates that complex 3 exhibits an antiferromagnetic coupling between adjacent Cu(II) ions. - Graphical abstract: Five new Cu(II)/Ag(I) complexes show interesting structural features from mononuclear, one-dimension, two-dimension to three-dimension under the influence of inorganic anions. The structural variation can be explained by the HSAB theory. - Highlights: • Five inorganic anion-dependent complexes are synthesized. • Structural variation can be explained by the hard-soft-acid-base (HSAB) theory. • The magnetic property of complex has been studied.

Three-dimensional mesoscale heterostructures of ZnO nanowire arrays epitaxially grown on CuGaO2 nanoplates as individual diodes.

Science.gov (United States)

Forticaux, Audrey; Hacialioglu, Salih; DeGrave, John P; Dziedzic, Rafal; Jin, Song

2013-09-24

We report a three-dimensional (3D) mesoscale heterostructure composed of one-dimensional (1D) nanowire (NW) arrays epitaxially grown on two-dimensional (2D) nanoplates. Specifically, three facile syntheses are developed to assemble vertical ZnO NWs on CuGaO2 (CGO) nanoplates in mild aqueous solution conditions. The key to the successful 3D mesoscale integration is the preferential nucleation and heteroepitaxial growth of ZnO NWs on the CGO nanoplates. Using transmission electron microscopy, heteroepitaxy was found between the basal planes of CGO nanoplates and ZnO NWs, which are their respective (001) crystallographic planes, by the observation of a hexagonal Moiré fringes pattern resulting from the slight mismatch between the c planes of ZnO and CGO. Careful analysis shows that this pattern can be described by a hexagonal supercell with a lattice parameter of almost exactly 11 and 12 times the a lattice constants for ZnO and CGO, respectively. The electrical properties of the individual CGO-ZnO mesoscale heterostructures were measured using a current-sensing atomic force microscopy setup to confirm the rectifying p-n diode behavior expected from the band alignment of p-type CGO and n-type ZnO wide band gap semiconductors. These 3D mesoscale heterostructures represent a new motif in nanoassembly for the integration of nanomaterials into functional devices with potential applications in electronics, photonics, and energy.

Structural, dynamical & electronic properties of CaCuO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Agrawal, B.K.; Agrawal, S. [Allahabad Univ. (India)

1994-12-31

The scalar relativistic version of an accurate first principles full potential self- consistent linearized muffin tin orbital (LMTO) method has been employed for describing the physical properties of the parent system of the high-Tc oxide superconductors, i.e., CaCuO2. The presently employed modified version of the LMTO method is quite fast and goes beyond the usual LMTO-ASA method in the sense that it permits a completely general shape of the potential and the charge density. Also, in contrast to LMTO-ASA, the present method is also capable of treating distorted lattice structures accurately. The calculated values of the lattice parameters of pure CaCuO2 lie within 3% of the experimentally measured values for the Sr-doped system Ca(.86)Sr(.14)CuO(2). The computed electronic structures and the density of states is quite similar to those of the other oxide superconductors, except of their three- dimensional character because of the presence of strong coupling between the closely spaced CuO2 layers. The van Hove singularity peak appears slightly below the Fermi level and a small concentration of oxygenation /or/ substitutional doping may pin it as the Fermi level. The calculated frequencies for some symmetric frozen phonons for undoped CaCuO2 are quite near to the measured data for the Sr-doped CaCuO2.

Two interpenetrating Cu{sup II}/Ni{sup II}-coordinated polymers based on an unsymmetrical bifunctional N/O-tectonic: Syntheses, structures and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Liu, Yong-Liang [College of Materials & Chemical Engineering, China Three Gorges University, Yichang 443002 (China); Department of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Comprehensive Utilization of Tailings Resources, Shang Luo University, Shang Luo 726000 (China); Wu, Ya-Pan [College of Materials & Chemical Engineering, China Three Gorges University, Yichang 443002 (China); Li, Dong-Sheng, E-mail: lidongsheng1@126.com [College of Materials & Chemical Engineering, China Three Gorges University, Yichang 443002 (China); Dong, Wen-Wen [College of Materials & Chemical Engineering, China Three Gorges University, Yichang 443002 (China); Zhou, Chun-Sheng [Department of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Comprehensive Utilization of Tailings Resources, Shang Luo University, Shang Luo 726000 (China)

2015-03-15

Two new interpenetrating Cu{sup II}/Ni{sup II} coordination polymers, based on a unsymmetrical bifunctional N/O-tectonic 3-(pyrid-4′-yl)-5-(4″-carbonylphenyl)-1,2,4-triazolyl (H{sub 2}pycz), ([Cu-(Hpycz){sub 2}]·2H{sub 2}O){sub n} (1) and ([Ni(Hpycz){sub 2}]·H{sub 2}O){sub n} (2), have been solvothermally synthesized and structure characterization. Single crystal X-ray analysis indicates that compound 1 shows 2-fold parallel interpenetrated 4{sup 4}-sql layers with the same handedness. The overall structure of 1 is achiral—in each layer of doubly interpenetrating nets, the two individual nets have the opposite handedness to the corresponding nets in the adjoining layers—while 2 features a rare 8-fold interpenetrating 6{sup 6}-dia network that belongs to class IIIa interpenetration. In addition, compounds 1 and 2 both show similar paramagnetic characteristic properties. - Graphical abstract: Two new Cu(II)/Ni(II) coordination polymers present 2D parallel 2-fold interpenetrated 4{sup 4}-sql layers and a rare 3D 8-fold interpenetrating 6{sup 6}-dia network. In addition, magnetic susceptibility measurements show similar paramagnetic characteristic for two complexes. - Highlights: • A new unsymmetrical bifunctional N/O-tectonic as 4-connected spacer. • A 2-fold parallel interpenetrated sql layer with the same handedness. • A rare 8-fold interpenetrating dia network (class IIIa)

Lattice thermal conductivity in layered BiCuSeO

KAUST Repository

Kumar, S.

2016-06-30

We quantify the low lattice thermal conductivity in layered BiCuSeO (the oxide with the highest known figure of merit). It turns out that the scattering of acoustical into optical phonons is strongly enhanced in the material because of the special structure of the phonon dispersion. For example, at room temperature the optical phonons account for an enormous 42% of the lattice thermal conductivity. We also quantify the anisotropy of the lattice thermal conductivity and determine the distribution of the mean free path of the phonons at different temperatures to provide a guide for tuning the thermal properties. © the Owner Societies 2016.

Bi-epitaxial YBa2Cu3Ox Thin Films on Tilted-axes NdGaO3 Substrates with CeO2 Seeding Layer

International Nuclear Information System (INIS)

Mozhaev, P B; Mozhaeva, J E; Jacobsen, C S; Hansen, J Bindslev; Bdikin, I K; Luzanov, V A; Kotelyanskii, I M; Zybtsev, S G

2006-01-01

Bi-epitaxial YBa 2 Cu 3 O x (YBCO) thin films with out-of-plane tilt angle in the range 18 - 27 0 were manufactured using pulsed laser deposition on NdGaO 3 tilted-axes substrates with CeO 2 seeding layers. The YBCO thin film orientation over the seeding layer depended on deposition conditions. Removal of the seeding layer from part of the substrate surface by ionbeam etching resulted in formation of a bi-epitaxial thin film with different c-axis orientation of two parts of the film. The bi-epitaxial film orientation and structure were studied using X-ray diffraction techniques, and surface morphology was observed with atomic force microscope (AFM). Photolithography and ion-beam etching techniques were used for patterning bi-epitaxial thin films. Electrical characterization of the obtained structures was performed

Smooth surfaces in very thin GdBa{sub 2}Cu{sub 3}O{sub 7−δ} films for application in superconducting tunnel junctions

Energy Technology Data Exchange (ETDEWEB)

Navarro, H., E-mail: henrynavarro@cab.cnea.gov.ar [Instituto Balseiro, Universidad Nacional de Cuyo & CNEA, 8400 Bariloche (Argentina); Centro Atómico Bariloche, Comisión Nacional de Energía Atómica. Av. Bustillo 9500, 8400 San Carlos de Bariloche (Argentina); Sirena, M. [Instituto Balseiro, Universidad Nacional de Cuyo & CNEA, 8400 Bariloche (Argentina); Centro Atómico Bariloche, Comisión Nacional de Energía Atómica. Av. Bustillo 9500, 8400 San Carlos de Bariloche (Argentina); Kim, Jeehoon [Department of Physics, Pohang University of Science and Technology, Pohang (Korea, Republic of); CALDES, Institute for Basic Science, Pohang (Korea, Republic of); Haberkorn, N. [Instituto Balseiro, Universidad Nacional de Cuyo & CNEA, 8400 Bariloche (Argentina); Centro Atómico Bariloche, Comisión Nacional de Energía Atómica. Av. Bustillo 9500, 8400 San Carlos de Bariloche (Argentina)

2015-03-15

Highlights: • A detailed study of the morphological properties of GdBa{sub 2}Cu{sub 3}O{sub 7−δ} thin films was realized. • The inclusion of a very thin SrTiO{sub 3} buffer layer modifies the surface of the SrTiO{sub 3} substrates. • The inclusion of the buffer layer suppress the three dimensional nucleation in the GdBa{sub 2}Cu{sub 3}O{sub 7−δ} film. • GdBa{sub 2}Cu{sub 3}O{sub 7−δ} films with large areas free of topological defects and T{sub c} close to liquid nitrogen can be obtained. - Abstract: This paper provides a systematic analysis of the morphology and the superconducting critical temperature obtained in very thin GdBa{sub 2}Cu{sub 3}O{sub 7−δ} films grown on (0 0 1) SrTiO{sub 3} substrates by DC sputtering. We find that the use of a very thin SrTiO{sub 3} buffer layer (≈2 nm) modify the nucleation of GdBa{sub 2}Cu{sub 3}O{sub 7−δ} on the surface of the substrate reducing the formation of 3 dimensional clusters. Our results demonstrate that 16 nm thick GdBa{sub 2}Cu{sub 3}O{sub 7−δ} films with an average root-mean-square (RMS) smaller than 1 nm and large surface areas (up 10 μm{sup 2}) free of 3 dimensional topological defects can be obtained. In films thinner than 24 nm the onset (zero resistance) of superconducting transition of the films is reduced, being close to liquid nitrogen. This fact can be associated with stress reducing the orthorhombicity and slightly drop in oxygen stoichiometry.

Relaxation of the electronic states at a thin-layer YBa2Cu 3O7/PrBa2Cu3O7 interface

KAUST Repository

Gó mez, Javier Alexandra M; Larkin, Ivan A.; Schwingenschlö gl, Udo

2010-01-01

We discuss in detail spin-polarized electronic structure calculations for the 1 × 1 YBa2Cu3O7/PrBa 2Cu3O7 superlattice. Our results are based on the full-potential linear augmented plane wave method and the generalized gradient approximation for the exchange-correlation functional. The on-site Coulomb interaction affecting the correlated Cu 3d and Pr 4f electrons is taken into consideration. At first glance the YBa2Cu3O 7/PrBa2Cu3O7 interface appears to be inert, i.e., the electronic states do not show a clear sign of interaction between the two component materials. Nonetheless, a total energy analysis points to a significant modification of the magnetic coupling in the vicinity of the interface due to the relaxation of the electronic structure. © 2010 Elsevier B.V. All rights reserved.

Relaxation of the electronic states at a thin-layer YBa2Cu 3O7/PrBa2Cu3O7 interface

KAUST Repository

Gómez, Javier Alexandra M

2010-11-01

We discuss in detail spin-polarized electronic structure calculations for the 1 × 1 YBa2Cu3O7/PrBa 2Cu3O7 superlattice. Our results are based on the full-potential linear augmented plane wave method and the generalized gradient approximation for the exchange-correlation functional. The on-site Coulomb interaction affecting the correlated Cu 3d and Pr 4f electrons is taken into consideration. At first glance the YBa2Cu3O 7/PrBa2Cu3O7 interface appears to be inert, i.e., the electronic states do not show a clear sign of interaction between the two component materials. Nonetheless, a total energy analysis points to a significant modification of the magnetic coupling in the vicinity of the interface due to the relaxation of the electronic structure. © 2010 Elsevier B.V. All rights reserved.

Three-dimensional flow in electromagnetically driven shallow two-layer fluids

NARCIS (Netherlands)

Akkermans, R.A.D.; Kamp, L.P.J.; Clercx, H.J.H.; van Heijst, G.J.F.

2010-01-01

Recent experiments on a freely evolving dipolar vortex in a homogeneous shallow fluid layer have clearly shown the existence and evolution of complex three-dimensional 3D flow structures. The present contribution focuses on the 3D structures of a dipolar vortex evolving in a stable shallow two-layer

Three-Dimensional Computer-Assisted Two-Layer Elastic Models of the Face.

Science.gov (United States)

Ueda, Koichi; Shigemura, Yuka; Otsuki, Yuki; Fuse, Asuka; Mitsuno, Daisuke

2017-11-01

To make three-dimensional computer-assisted elastic models for the face, we decided on five requirements: (1) an elastic texture like skin and subcutaneous tissue; (2) the ability to take pen marking for incisions; (3) the ability to be cut with a surgical knife; (4) the ability to keep stitches in place for a long time; and (5) a layered structure. After testing many elastic solvents, we have made realistic three-dimensional computer-assisted two-layer elastic models of the face and cleft lip from the computed tomographic and magnetic resonance imaging stereolithographic data. The surface layer is made of polyurethane and the inner layer is silicone. Using this elastic model, we taught residents and young doctors how to make several typical local flaps and to perform cheiloplasty. They could experience realistic simulated surgery and understand three-dimensional movement of the flaps.

Triangle islands and cavities on the surface of evaporated Cu(In, Ga)Se2 absorber layer

International Nuclear Information System (INIS)

Han Anjun; Zhang Yi; Liu Wei; Li Boyan; Sun Yun

2012-01-01

Highlights: ► Lots of uncommon triangle islands and cavities are found on (1 1 2) planes terminated by Se atoms of evaporated Cu(In, Ga)Se 2 thin films. ► Se ad-dimer as a nucleus, Cu atom diffusion from Cu(In, Ga)Se 2 grains brings the epitaxial triangle island. ► The triangle islands grow with a two-dimensional layered mode. ► The triangle cavities are formed due to the insufficient coalescence of triangle islands. ► The performance of solar cell without triangle islands is improved. - Abstract: Cu(In, Ga)Se 2 (CIGS) thin films are co-evaporated at a constant substrate temperature of 500 °C on the Mo/soda lime glass substrates. The structural properties and chemical composition of the CIGS films are studied by an X-ray diffractometer (XRD) and an X-ray fluorescent spectrometer (XRF), respectively. A scanning electron microscope (SEM) is used to study the surface morphology. Lots of uncommon triangle islands and cavities are found on some planes of the CIGS thin films. We investigate the formation mechanism of these triangle islands. It is found that the planes with the triangle islands are (1 1 2) planes terminated by Se atoms. Se ad-dimer as a nucleus, Cu diffusion from CIGS grains brings the epitaxial triangle islands which grow with a two-dimensional layered mode. The film with Cu/(Ga + In) = 0.94–0.98 is one key of the formation of these islands. The triangle cavities are formed due to the insufficient coalescence of triangle islands. The growth of triangle islands brings a compact surface with large layered grains and many jagged edges, but no triangle cavity. Finally, we compare the performance of solar cell with triangle islands and layered gains. It is found that the performance of solar cell with large layered gains is improved.

Growth of intermetallics between Sn/Ni/Cu, Sn/Ag/Cu and Sn/Cu layered structures

International Nuclear Information System (INIS)

Horváth, Barbara; Illés, Balázs; Shinohara, Tadashi

2014-01-01

Intermetallic growth mechanisms and rates are investigated in Sn/Ni/Cu, Sn/Ag/Cu and Sn/Cu layer systems. An 8–10 μm thick Sn surface finish layer was electroplated onto a Cu substrate with a 1.5–2 μm thick Ni or Ag barrier layer. In order to induce intermetallic layer growth, the samples were aged in elevated temperatures: 50 °C and 125 °C. Intermetallic layer growth was checked by focused ion beam–scanning ion microscope. The microstructures and chemical compositions of the intermetallic layers were observed with a transmission electron microscope. It has been found that Ni barrier layers can effectively block the development of Cu 6 Sn 5 intermetallics. The intermetallic growth characteristics in the Sn/Cu and Sn/Ni/Cu systems are very similar. The intermetallic layer grows towards the Sn layer and forms a discrete layer. Differences were observed only in the growth gradients and surface roughness of the intermetallic layer which may explain the different tin whiskering properties. It was observed that the intermetallic layer growth mechanisms are completely different in the Ag barrier layers compared to the Ni layers. In the case of Sn/Ag/Cu systems, the Sn and Cu diffused through the Ag layer, formed Cu 6 Sn 5 intermetallics mainly at the Sn/Ag interface and consumed the Ag barrier layer. - Highlights: • Intermetallic growth was characterised in Sn/Ni/Cu, Sn/Ag/Cu and Sn/Cu layer systems. • Intermetallic growth rates and roughness are similar in the Sn/Cu and Sn/Ni/Cu systems. • Sn/Ni/Cu system contains the following intermetallic layer structure Sn–Ni3Sn4–Ni3Sn2–Ni3Sn–Ni. • In the case of Sn/Ag/Cu systems the Sn and Cu diffusion consumes the Ag barrier layer. • When Cu reaches the Sn/Ag interface a large amount of Cu 6 Sn 5 forms above the Ag layer

Two New Three-Dimensional Pillared-Layer Co(II and Cu(II Frameworks Involving a [M2(EO-N32] Motif from a Semi-Flexible N-Donor Ligand, 5,5′-Bipyrimidin: Syntheses, Structures and Magnetic Properties

Directory of Open Access Journals (Sweden)

Zu-Zhen Zhang

2018-02-01

Full Text Available Two new three-dimensional (3D Co(II- and Cu(II-azido frameworks, [Co2(N34(bpym2]n (1 and [Cu2(N34(bpym]n (2, were successfully synthesized by introducing a semi-flexible N-donor ligand, 5,5′-bipyrimidin (bpym, with different bridging modes and orientations. Compounds 1 and 2 were structurally characterized by X-ray crystallography, IR spectroscopy, thermogravimetry and elemental analysis. Compounds 1 and 2 are 3D pillared-layer frameworks with double end-on (EO azido bridged dinuclear motifs, [M2(EO-N32]. In Compound 1, the bpym ligands show trans μ2-bridging mode and the role as pillars to connect the Co(II-azido layers, composed of [Co2(EO-N32] motifs and single end-to-end (EE azido bridges, to a 3D network with BN topology. In contrast, in 2, the bpym ligand adopts a twisted μ4-bridging mode, which not only connects the adjacent [Cu2(EO-N32] units to a layer, but also functions as a pillar for the layers of the 3D structure. The structural diversities between the two types of architectures can be attributed to the coordination geometry preference of the metal ions (octahedral for Co2+ and square pyramidal for Cu2+. Magnetic investigations revealed that Compound 1 exhibits ferromagnetic-like magnetic ordering due to spin canting with a critical temperature, TC = 33.0 K, and furthers the field-induced magnetic transitions of metamagnetism at temperatures below TC. Compound 2 shows an antiferromagnetic ordering with TN = 3.05 K and a field-induced magnetic transition of spin-flop at temperatures below the TN.

The effect of inducing uniform Cu growth on formation of electroless Cu seed layer

International Nuclear Information System (INIS)

Lim, Taeho; Kim, Myung Jun; Park, Kyung Ju; Kim, Kwang Hwan; Choe, Seunghoe; Lee, Young-Soo; Kim, Jae Jeong

2014-01-01

The uniformity of Cu growth on Pd nanocatalysts was controlled by using organic additives in the formation of electroless Cu seed layers. Polyethylene glycol (PEG, Mw. 8000) not only reduced the deposition rate but also improved the uniformity of Cu growth on each Pd nanocatalyst during the seed layer formation. The stronger suppression effect of PEG on Cu than on Pd reduced the difference in the deposition rate between the two surfaces, resulting in the uniform deposition. Meanwhile, bis(3-sulfopropyl) disulfide degraded the uniformity by strong and nonselective suppression. The sheet resistance measurement and atomic force microscopy imaging revealed that the uniform Cu growth by PEG was more advantageous for the formation of a thin and smooth Cu seed layer than the non-uniform growth. The uniform Cu growth also had a positive influence on the subsequent Cu electrodeposition: the 60-nm-thick electrodeposited Cu film on the Cu seed layer showed low resistivity (2.70 μΩ·cm), low surface roughness (6.98 nm), and good adhesion strength. - Highlights: • Uniform Cu growth on Pd was achieved in formation of electroless Cu seed layer. • PEG addition to electroless bath improved the uniformity of Cu growth on Pd. • A thin, smooth and continuous Cu seed layer was obtained with PEG. • Adhesion strength of the Cu seed layer was also improved with PEG. • The uniformity improvement positively affected subsequent Cu electrodeposition

Efficiency enhancement using a Zn1- x Ge x -O thin film as an n-type window layer in Cu2O-based heterojunction solar cells

Science.gov (United States)

Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

2016-05-01

Efficiency enhancement was achieved in Cu2O-based heterojunction solar cells fabricated with a zinc-germanium-oxide (Zn1- x Ge x -O) thin film as the n-type window layer and a p-type Na-doped Cu2O (Cu2O:Na) sheet prepared by thermally oxidizing Cu sheets. The Ge content (x) dependence of the obtained photovoltaic properties of the heterojunction solar cells is mainly explained by the conduction band discontinuity that results from the electron affinity difference between Zn1- x Ge x -O and Cu2O:Na. The optimal value of x in Zn1- x Ge x -O thin films prepared by pulsed laser deposition was observed to be 0.62. An efficiency of 8.1% was obtained in a MgF2/Al-doped ZnO/Zn0.38Ge0.62-O/Cu2O:Na heterojunction solar cell.

Growth and transport properties of multilayer superconducting films of Nd1.83Co0.17CuOx/YBa2Cu3O7-δ

International Nuclear Information System (INIS)

Gupta, A.; Gross, R.; Olsson, E.; Segmuller, A.; Koren, G.

1990-01-01

This paper reports on strained multilayer thin films of YBa 2 Cu 3 O 7-δ /Nd 1.83 Ce 0.17 CuO x that have been prepared by laser ablation deposition. For individual layers below a critical layer thickness of about 250 Angstrom, coherency strain compresses the Nd 1.83 Ce 0.17 CuO x lattice and expands the YBa 2 Cu 3 O 7-δ lattice. The orthorhombic distortion in the YBa 2 Cu 3 O 7-δ layers is also removed. Depending on their oxygen content, either the YBa 2 Cu 3 O 7-δ , or the Nd 1.83 Ce 0.17 CuO x layers are superconducting in these multilayers. The strain-induced structural modification has a significant influence on the superconducting transition temperature and critical current density of the YBa 2 Cu 3 O 7-δ layers. Zero field critical current densities as high as 1.1 x 10 7 A/cm 2 at 77K have been measured for the YBa 2 Cu 3 O 7-δ layers

Poly[[(μ4-benzene-1,3,5-tricarboxylato-κ4O1:O1′:O2:O3bis(2,2-bipyridine-κ2N,N′(μ2-hydroxidodicopper(II] trihydrate

Directory of Open Access Journals (Sweden)

Mohamed N. El-kaheli

2014-07-01

Full Text Available In the title two-dimensional coordination polymer, {[Cu2(C9H3O6(OH(C10H8N22]·3H2O}n, each of the two independent CuII atoms is coordinated by a bridging OH group, two O atoms from two benzene-1,3,5-tricarboxylate (L ligands and two N atoms from a 2,2- bipyridine (bipy ligand in a distorted square-pyramidal geometry. Each L ligand coordinates four CuII atoms, thus forming a polymeric layer parallel to the bc plane with bipy molecules protruding up and down. The lattice water molecules involved in O—H...· O hydrogen bonding are situated in the inner part of each layer. The crystal packing is consolidated by π–π interactions between the aromatic rings of bipy ligands from neigbouring layers [intercentroid distance = 3.762 (3 Å].

Properties of spin-1/2 triangular-lattice antiferromagnets CuY2Ge2O8 and CuLa2Ge2O8

Science.gov (United States)

Cho, Hwanbeom; Kratochvílová, Marie; Sim, Hasung; Choi, Ki-Young; Kim, Choong Hyun; Paulsen, Carley; Avdeev, Maxim; Peets, Darren C.; Jo, Younghun; Lee, Sanghyun; Noda, Yukio; Lawler, Michael J.; Park, Je-Geun

2017-04-01

We found new two-dimensional (2D) quantum (S =1 /2 ) antiferromagnetic systems: Cu R E2G e2O8 (R E =Y and La). According to our analysis of high-resolution x-ray and neutron diffraction experiments, the Cu network of Cu R E2G e2O8 (R E =Y and La) exhibits a 2D triangular lattice linked via weak bonds along the perpendicular b axis. Our bulk characterizations from 0.08 to 400 K show that they undergo a long-range order at 0.51(1) and 1.09(4) K for the Y and La systems, respectively. Interestingly, they also exhibit field induced phase transitions. For theoretical understanding, we carried out the density functional theory (DFT) band calculations to find that they are typical charge-transfer-type insulators with a gap of Eg≅2 eV . Taken together, our observations make Cu R E2G e2O8 (R E =Y and La) additional examples of low-dimensional quantum spin triangular antiferromagnets with the low-temperature magnetic ordering.

Cu-Ni nanowire-based TiO{sub 2} hybrid for the dynamic photodegradation of acetaldehyde gas pollutant under visible light

Energy Technology Data Exchange (ETDEWEB)

Zhu, Shuying [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049 (China); Xie, Xiaofeng, E-mail: xxfshcn@163.com [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Chen, Sheng-Chieh [College of Science and Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Tong, Shengrui [Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Lu, Guanhong [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Pui, David Y.H. [College of Science and Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Sun, Jing [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

2017-06-30

Graphical abstract: One-dimensional Cu-Ni bimetallic nanowires were introduced into TiO{sub 2}-based matrix to enhance their photocatalysis efficiency and expand their light absorption range. - Highlights: • Cu-Ni nanowire-based TiO{sub 2} hybrid photocatalyst. • One-dimensional electron pathways and surface plasmon resonance effects. • Dynamic photodegradation of acetaldehyde gas pollutant. - Abstract: One-dimensional bimetallic nanowires were introduced into TiO{sub 2}-based matrix to enhance their photocatalysis efficiency and expand their light absorption range in this work. Recently, metal nanowires have attracted many attention in photocatalyst research fields because of their favorable electronic transmission properties and especially in the aspect of surface plasmon resonance effects. Moreover, Cu-Ni bimetallic nanowires (Cu-Ni NWs) have shown better chemical stability than ordinary monometallic nanowires in our recent works. Interestingly, it has been found that Ni sleeves of the bimetallic nanowires also can modify the Schottky barrier of interface between TiO{sub 2} and metallic conductor, so that be beneficial to the separation of photogenerated carriers in the Cu-Ni/TiO{sub 2} network topology. Hence, a novel heterostructured photocatalyst composed of Cu-Ni NWs and TiO{sub 2} nanoparticles (NPs) was fabricated by one-step hydrolysis approach to explore its photocatalytic performance. TEM and EDX mapping images of this TiO{sub 2} NPs @Cu-Ni NWs (TCN) hybrid displayed that Cu-Ni NWs were wrapped by compact TiO{sub 2} layer and retained the one-dimensional structure in matrix. In experiments, the photocatalytic performance of the TCN nanocomposite was significantly enhanced comparing to pure TiO{sub 2}. Acetaldehyde, as a common gas pollutant in the environment, was employed to evaluate the photodegradation efficiency of a series of TCN nanocomposites under continuous feeding. The TCN exhibited excellent potodegradation performance, where the

Syntheses, structures and properties of three new two-dimensional Cu(I)-Ln(III) heterometallic coordination polymers based on 2,2'-dipyridyl-5,5'-dicarboxylate ligands.

Science.gov (United States)

Zhao, Junwei; Cheng, Yamin; Shang, Sensen; Zhang, Fang; Chen, Li; Chen, Lijuan

2013-12-01

Three new two-dimensional Cu(I)-Ln(III) heterometallic coordination polymers [Ln(III)Cu2(I)(Hbpdc)4] · Cl · xH2O [Ln(III) = La(III), x = 8 (1); Ln(III) = Pr(III), x=9 (2); Ln(III) = Eu(III), x = 8 (3)] (H2bpdc = 2,2'-bipyridyl-5,5'-dicarboxylic acid) have been prepared under hydrothermal conditions and structurally characterized by elemental analyses, inductively coupled plasma atomic emission spectrometry (ICP-AES) analyses, IR spectra, X-ray photoelectron spectroscopy (XPS) and single-crystal X-ray diffraction. X-ray diffraction indicates that the isomorphic 1-3 display the two-dimensional sheet structure constructed from [Cu(I)(Hbpdc)2](-) fragments through Ln(3+) connectors. Moreover, the solid-state photoluminescence measurements of 3 indicate that the Eu(III) ions, Hbpdc(-) ligands and Cu(I) cations make contributions to its luminescent properties simultaneously. Copyright © 2013 Elsevier B.V. All rights reserved.

Thermochemical properties of oxides in Y-Ba-Cu-O, Sr-Bi-O, Cu-Nb-O, Sr-Cu-O, Ca-Cu-O, Cu-O and Hg-Ba-Ca-Cu-O systems

International Nuclear Information System (INIS)

Moiseev, G.K.; Vatolin, N.A.; Il'inykh, N.I.

2000-01-01

Thermochemical properties (ΔH 0 298 , S 0 298 , H 0 298 -H 0 0 , C p (T), C p at T>T melt ) of complex oxides in Y-Ba-Cu-O, Sr-Bi-O, Cu-Nb-O, Sr-Cu-O, Ca-Cu-O, Cu-O and Hg-Ba-Ca-Cu-O systems obtained with application of calculation methods are presented. Nonexperimental methods of estimation, revision and correction of standard formation enthalpies of inorganic compounds are described [ru

Photovoltaic performance of bithiazole-bridged dyes-sensitized solar cells employing semiconducting quantum dot CuInS2 as barrier layer material.

Science.gov (United States)

Guo, Fuling; He, Jinxiang; Li, Jing; Wu, Wenjun; Hang, Yandi; Hua, Jianli

2013-10-15

In this work, the quantum dot CuInS2 layer was deposited on TiO2 film using successive ionic layer absorption and reaction (SILAR) method, and then two bithiazole-bridged dyes (BTF and BTB) were sensitized on the CuInS2/TiO2 films to form dye/CuInS2/TiO2 photoanodes for DSSCs. It was found that the quantum dots CuInS2 as an energy barrier layer not only could effectively improve open-circuit voltage (Voc) of solar cell, but also increase short-circuit photocurrent (Jsc) compared to the large decrease in Jsc of ZnO as energy barrier layer. The electrochemical impedance spectroscopy (EIS) measurement showed that the CuInS2 formed a barrier layer to suppress the recombination from injection electron to the electrolyte and improve open-circuit voltage. Finally, the open-circuit voltage increased about 22 and 27mV for BTF and BTB-/CuInS2/TiO2-based cells, the overall conversion efficiencies also reached to 7.20% and 6.74%, respectively. Copyright © 2013 Elsevier Inc. All rights reserved.

The effect of Cu on the properties of CdO/Cu/CdO multilayer films for transparent conductive electrode applications

Energy Technology Data Exchange (ETDEWEB)

Raaif, M.; Mohamed, S.H. [Sohag University, Physics Department, Faculty of Science, Sohag (Egypt)

2017-06-15

Transparent conductive CdO/Cu/CdO multilayer films were prepared using rf plasma magnetron sputtering and electron beam evaporation techniques. The CdO layers were prepared using rf plasma magnetron sputtering, while the Cu interlayer was prepared by electron beam evaporation technique. The Cu layer thickness was varied between 1 and 10 nm. The structural and optical properties as well as the sheet resistance of the multilayer films were studied. X-ray diffraction measurements revealed the presence of cubic CdO structure and the Cu peak was only observed for the multilayers prepared with 10 nm of Cu. It has been observed that the Cu interlayer thickness has a great influence on the optical and electrical properties of the multilayers. The transmittance of the multilayer films decreased while the reflectance increased with increasing Cu interlayer thickness. The refractive index and the extinction coefficient of the multilayer films were calculated. The estimated optical band gap values were found to be decreased from 2.75 ± 0.02 to 2.40 ± 0.02 eV as the Cu interlayer thickness increased from 1 to 10 nm. The sheet resistance was sensitive to the Cu interlayer thickness and it decreased with increasing Cu interlayer thickness. A sheet resistSSance of 21.7 Ω/sq, an average transmittance (between 700 and 1000 nm) of 77%, and an optical band gap of 2.5 ± 0.02 eV were estimated for the multilayer film with 2 nm Cu layer. The multilayer film with 2 nm Cu layer has the highest figure of merit value of 3.2 x 10{sup -3} Ω{sup -1}. This indicates that the properties of this multilayer film are suitable for transparent conductive electrode applications. (orig.)

Modeling Photoelectron Spectra of CuO, Cu2O, and CuO2 Anions with Equation-of-Motion Coupled-Cluster Methods: An Adventure in Fock Space.

Science.gov (United States)

Orms, Natalie; Krylov, Anna I

2018-04-12

The experimental photoelectron spectra of di- and triatomic copper oxide anions have been reported previously. We present an analysis of the experimental spectra of the CuO - , Cu 2 O - , and CuO 2 - anions using equation-of-motion coupled-cluster (EOM-CC) methods. The open-shell electronic structure of each molecule demands a unique combination of EOM-CC methods to achieve an accurate and balanced representation of the multiconfigurational anionic- and neutral-state manifolds. Analysis of the Dyson orbitals associated with photodetachment from CuO - reveals the strong non-Koopmans character of the CuO states. For the lowest detachment energy, a good agreement between theoretical and experimental values is obtained with CCSD(T) (coupled-cluster with single and double excitations and perturbative account of triple excitations). The (T) correction is particularly important for Cu 2 O - . Use of a relativistic pseudopotential and matching basis set improves the quality of results in most cases. EOM-DIP-CCSD analysis of the low-lying states of CuO 2 - reveals multiple singlet and triplet anionic states near the triplet ground state, adding an extra layer of complexity to the interpretation of the experimental CuO 2 - photoelectron spectrum.

Hydrogen peroxide-assisted synthesis of novel three-dimensional octagonal-like CuO nanostructures with enhanced visible-light-driven photocatalytic activity

Science.gov (United States)

Chen, Xiangyu; Chu, Deqing; Wang, Limin; Hu, Wenhui; Yang, Huifang; Sun, Jingjing; Zhu, Shaopeng; Wang, Guowei; Tao, Jian; Zhang, Songsong

2018-04-01

Novel three-dimensional octagonal-like CuO micro-/nanostructures with diameters ranging from 10 to 15 μm have been successfully prepared by hydrogen peroxide-assisted hydrothermal method and subsequent calcination. The product morphology can be changed by simply ordering the amount of hydrogen peroxide (H2O2). When the amounts of H2O2 is increased, the length of the corner portion is increased and the width is narrower. The obtained octagonal CuO nanostructures were evaluated for their ability for the degradation of hazardous organic contaminants in water under visible-light irradiation. Comparing with commercial CuO and other CuO products, the CuO octagonal nanostructures exhibit excellent performance for photocatalytic decomposition of RhB (Rhodamine B). It is well established that effective photocatalytic performance results from its unique 3D octagonal nanostructures. We believe that the present work will provide some ideas for further fabrication of other novel nanostructures and exploration of their applications.

Cu and Cu(Mn) films deposited layer-by-layer via surface-limited redox replacement and underpotential deposition

Energy Technology Data Exchange (ETDEWEB)

Fang, J.S., E-mail: jsfang@nfu.edu.tw [Department of Materials Science and Engineering, National Formosa University, Huwei 63201, Taiwan (China); Sun, S.L. [Department of Materials Science and Engineering, National Formosa University, Huwei 63201, Taiwan (China); Cheng, Y.L. [Department of Electrical Engineering, National Chi-Nan University, Nan-Tou 54561, Taiwan (China); Chen, G.S.; Chin, T.S. [Department of Materials Science and Engineering, Feng Chia University, Taichung 40724, Taiwan (China)

2016-02-28

Graphical abstract: - Abstract: The present paper reports Cu and Cu(Mn) films prepared layer-by-layer using an electrochemical atomic layer deposition (ECALD) method. The structure and properties of the films were investigated to elucidate their suitability as Cu interconnects for microelectronics. Previous studies have used primarily a vacuum-based atomic layer deposition to form a Cu metallized film. Herein, an entirely wet chemical process was used to fabricate a Cu film using the ECALD process by combining underpotential deposition (UPD) and surface-limited redox replacement (SLRR). The experimental results indicated that an inadequate UPD of Pb affected the subsequent SLRR of Cu and lead to the formation of PbSO{sub 4}. A mechanism is proposed to explain the results. Layer-by-layer deposition of Cu(Mn) films was successfully performed by alternating the deposition cycle-ratios of SLRR-Cu and UPD-Mn. The proposed self-limiting growth method offers a layer-by-layer wet chemistry-based deposition capability for fabricating Cu interconnects.

Cu-implanted ZnO nanorods array film: An aqueous synthetic approach

Energy Technology Data Exchange (ETDEWEB)

Singh, Ajaya Kumar, E-mail: ajayaksingh_au@yahoo.co.in [Department of Chemistry, Govt. VYT PG. Autonomous College Durg, Chhattisgarh (India); Thool, Gautam Sheel [Department of Chemistry, Govt. VYT PG. Autonomous College Durg, Chhattisgarh (India); Singh, R.S. [Department of Physics, Govt. D.T. College, Utai, Durg, Chhattisgarh (India); Singh, Surya Prakash, E-mail: spsingh@iict.res.in [Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology, Uppal road, Tarnaka, Hyderabad 500007 (India)

2015-01-05

Highlights: • Cu doped ZnO nanorods were synthesized using low temperature aqueous solution method. • We demonstrated the capping action of TEA via theoretical simulation. • Raman analysis revealed the presence of tensile strain in Cu doped ZnO nanorods. • Growth rate was found to be high in Cu doped ZnO nanorods. - Abstract: Pure and Cu doped ZnO nanorods array are synthesized via two step chemical bath deposition method. The seed layer is prepared by successive ionic layer adsorption reaction (SILAR) method. The synthesized materials have been systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy and photoluminescence (PL) spectroscopy. SEM pictures show the existence of vertically well aligned hexagonal ZnO nanorods. EDAX spectrum confirms the presence of Cu in ZnO nanorods. High intense peak of (0 0 2) plane and E{sub 2}{sup high} mode for XRD and Raman spectrum respectively, suggest the ZnO nanorods are adopted c-axis orientation perpendicular to substrate. XRD and Raman analysis shows the presence of tensile strain in Cu doped ZnO nanorods. Effect of Cu doping on lattice constants, unit cell volume and Zn–O bond length of ZnO nanorods have also been studied. Room temperature PL measurement exhibits two luminescence bands in the spectra i.e. UV emission centered at 3.215 eV and a broad visible band. Theoretical investigation for capping action of triethanolamine is done by Hartree–Fock (HF) method with 3-21G basis set using Gaussian 09 program package.

LaNiO{sub 3} buffer layers for high critical current density YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8{minus}{delta}} films

Energy Technology Data Exchange (ETDEWEB)

Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

1999-10-01

We demonstrate high critical current density superconducting films of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8{minus}{delta}} (Tl-2212) using LaNiO{sub 3} (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J{sub c} (5 K, H=0) than films grown directly on a bare LaAlO{sub 3} substrate. YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J{sub c} at all temperatures and fields compared to those grown on bare LaAlO{sub 3}, correlating to both {ital a}-axis grain and nonsuperconducting phase formation. LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films in coated conductor applications. {copyright} {ital 1999 American Institute of Physics.}

Collinear order in frustrated quantum antiferromagnet on square lattice (CuBr)LaNb2O7

International Nuclear Information System (INIS)

Oba, Noriaki; Kageyama, Hiroshi; Kitano, Taro

2006-01-01

Magnetic susceptibility, heat capacity, high-field magnetization and neutron diffraction measurements have been performed on a two-dimensional s=1/2 square-lattice system (CuBr)LaNb 2 O 7 , prepared by a topotactic ion-exchange reaction of a nonmagnetic double-layered perovskite RbLaNb 2 O 7 . (CuBr)LaNb 2 O 7 exhibits a second-order magnetic transition at 32K, in marked contrast to a spin-singlet nature for its Cl-based counterpart (CuCl)LaNb 2 O 7 , despite nearly identical structural parameters. The magnetic structure is a novel collinear antiferromagnetic (CAF) ordering characterized by a modulation vector q=(π, 0, π) with a reduced moment of 0.6μ B . Mixed ferromagnetic nearest-neighbor (J 1 ) and antiferromagnetic second-nearest-neighbor (J 2 ) interactions are of comparable strength (J 1 /k B =-35.6K and J 2 /k B =41.3K), placing the system in a more frustrated region of the CAF phase than ever reported. (author)

Improvement of performance in low temperature solid oxide fuel cells operated on ethanol and air mixtures using Cu-ZnO-Al2O3 catalyst layer

Science.gov (United States)

Morales, M.; Espiell, F.; Segarra, M.

2015-10-01

Anode-supported single-chamber solid oxide fuel cells with and without Cu-ZnO-Al2O3 catalyst layers deposited on the anode support have been operated on ethanol and air mixtures. The cells consist of gadolinia-doped ceria electrolyte, Ni-doped ceria anode, and La0.6Sr0.4CoO3-δ-doped ceria cathode. Catalyst layers with different Cu-ZnO-Al2O3 ratios are deposited and sintered at several temperatures. Since the performance of single-chamber fuel cells strongly depends on catalytic properties of electrodes for partial oxidation of ethanol, the cells are electrochemically characterized as a function of the temperature, ethanol-air molar ratio and gas flow rate. In addition, catalytic activities of supported anode, catalytic layer-supported anode and cathode for partial oxidation of ethanol are analysed. Afterwards, the effect of composition and sintering temperature of catalyst layer on the cell performance are determined. The results indicate that the cell performance can be significantly enhanced using catalyst layers of 30:35:35 and 40:30:30 wt.% Cu-ZnO-Al2O3 sintered at 1100 °C, achieving power densities above 50 mW cm-2 under 0.45 ethanol-air ratio at temperatures as low as 450 °C. After testing for 15 h, all cells present a gradual loss of power density, without carbon deposition, which is mainly attributed to the partial re-oxidation of Ni at the anode.

Synthesis and characterization of ZnO/Cu2O core–shell nanowires grown by two-step electrodeposition method

International Nuclear Information System (INIS)

Messaoudi, O.; Makhlouf, H.; Souissi, A.; Ben assaker, I.; Amiri, G.; Bardaoui, A.; Oueslati, M.; Bechelany, M.; Chtourou, R.

2015-01-01

Highlights: • ZnO/Cu 2 O core/shell nanowires have been grown by two-step electrodeposition method. • SEM confirmed the homogenous distribution of Cu 2 O on the deposited nanowires. • The X-ray diffraction demonstrated that the films were pure. • Optical transmissions measurements reveal an additional contribution at about 1.7 eV. • The ZnO/Cu 2 O structure is expected to have an advantage in photovoltaic application. - Abstract: ZnO/Cu 2 O core/shell nanowires have been grown by two-step electrodeposition method on ITO-coated glass substrates. The sample's morphology was explored by means of scanning electron microscopy (SEM). SEM images confirm the homogeneity of the nanowires and the presence of Cu 2 O shell on ZnO core. X-ray diffraction and Raman scattering measurements were used to investigate the purity and the crystallinity of the samples. Optical transmission measurements reveal an additional contribution at about 1.7 eV attributed to the type-II interfacial transition witch confirms the advantage of using the ZnO/Cu 2 O structure in photovoltaic application

Optical anisotropy of Bi2Sr2CaCu2O8

Science.gov (United States)

Kim, J. H.; Bozovic, I.; Mitzi, D. B.; Kapitulnik, A.; Harris, J. S., Jr.

1990-04-01

The optical anisotropy of Bi2Sr2CaCu2O8 in the 0.08-0.5-eV region is investigated by polarized reflectance measurements on single crystals. A very large anisotropy is found in this spectral region. The in-plane reflectance exhibits metallic behavior, while the c-axis reflectance exhibits insulatorlike behavior. This result is consistent with the large anisotropy found in the resistivity of Bi2Sr2CaCu2O8. Our spectroscopic data suggest that Bi2Sr2CaCu2O8 is a quasi-two-dimensional metal similar to La2-xSrxCuO4.

Preparation of Cu@Cu2O Nanocatalysts by Reduction of HKUST-1 for Oxidation Reaction of Catechol

OpenAIRE

Seongwan Jang; Chohye Yoon; Jae Myung Lee; Sungkyun Park; Kang Hyun Park

2016-01-01

HKUST-1, a copper-based metal organic framework (MOF), has been investigated as a catalyst in various reactions. However, the HKUST-1 shows low catalytic activity in the oxidation of catechol. Therefore, we synthesized Fe3O4@HKUST-1 by layer-by layer assembly strategy and Cu@Cu2O by reduction of HKUST-1 for enhancement of catalytic activity. Cu@Cu2O nanoparticles exhibited highly effective catalytic activity in oxidation of 3,5-di-tert-butylcatechol. Through this method, MOF can maintain the ...

Oxide p-n Heterojunction of Cu2O/ZnO Nanowires and Their Photovoltaic Performance

Directory of Open Access Journals (Sweden)

Seung Ki Baek

2013-01-01

Full Text Available Oxide p-n heterojunction devices consisting of p-Cu2O/n-ZnO nanowires were fabricated on ITO/glass substrates and their photovoltaic performances were investigated. The vertically arrayed ZnO nanowires were grown by metal organic chemical vapor deposition, which was followed by the electrodeposition of the p-type Cu2O layer. Prior to the fabrication of solar cells, the effect of bath pH on properties of the absorber layers was studied to determine the optimal condition of the Cu2O electrodeposition process. With the constant pH 11 solution, the Cu2O layer preferred the (111 orientation, which gave low electrical resistivity and high optical absorption. The Cu2O (pH 11/ZnO nanowire-based solar cell exhibited a higher conversion efficiency of 0.27% than the planar structure solar cell (0.13%, because of the effective charge collection in the long wavelength region and because of the enhanced junction area.

YCu(TeO32(NO3(H2O3: a novel layered tellurite

Directory of Open Access Journals (Sweden)

Stuart J. Mills

2016-08-01

Full Text Available A new hydrated yttrium copper tellurite nitrate, yttrium(III copper(II bis[trioxidotellurate(IV] nitrate trihydrate, has been synthesized hydrothermally in a Teflon-lined autoclave and structurally determined using synchrotron radiation. The new phase is the first example containing yttrium, copper and tellurium in one structure. Its crystal structure is unique, with relatively strongly bound layers extending parallel to (020, defined by YO8, CuO4 and TeO3 polyhedra, while the NO3− anions and one third of the water molecules lie between those layers. The structural unit consists of [Cu2(TeO34]4− loop-branched chains of {Cu...Te...Cu...Te} squares running parallel to [001], which are linked further into layers only through Y(O,H2O8 polyhedra. Weak `secondary' Te bonds and O—H...O hydrogen-bonding interactions, involving water molecules and layer O atoms, link the layers and interlayer species. IR spectroscopic data are also presented.

Heteroepitaxial growth of strained multilayer superconducting thin films of Nd1.83Ce0.17CuOx/YBa2Cu3O7-δ

International Nuclear Information System (INIS)

Gupta, A.; Gross, R.; Olsson, E.; Segmueller, A.; Koren, G.; Tsuei, C.C.

1990-01-01

Heteroepitaxial growth of strained multilayer thin films of YBa 2 Cu 3 O 7-δ /Nd 1.83 Ce 0.17 CuO x by pulsed-laser deposition is reported. The coherency strain results in biaxial compression of the tetragonal Nd 1.83 Ce 0.17 CuO x layers, whereas the biaxial tension in the YBa 2 Cu 3 O 7-δ layers removes the orthorhombic distortion and makes the unit cell isotropic in the basal plane (a=b). Depending on their oxygen content, either the YBa 2 Cu 3 O 7-δ or the Nd 1.83 Ce 0.17 CuO x layers are superconducting in these multilayers. The strain-induced structural modification has a significant influence on the superconducting transition temperature of the YBa 2 Cu 3 O 7-δ layers

Effects of cationic substitution on the electronic and magnetic properties of manganocuprate with a layered Eu3Ba2Mn2Cu2O12 structure

International Nuclear Information System (INIS)

Matsubara, Ichiro; Funahashi, Ryoji; Ueno, Kazuo; Ishikawa, Hiroshi; Kida, Noriaki; Ohno, Nobuhito

1998-01-01

Systematic studies on the effect of substitutions on the layered manganocuprate Eu 3 Ba 2 Mn 2 Cu 2 O 12 have been conducted. To introduce holes, the authors have made substitutions of Ca for Eu and/or Sc for Mn, (Eu 3-x Ca x )Ba 2 (Mn 2-y Sc y )Cu 2 O 12 . Single-phase compounds are obtained over a fairly wide range of x and y values for x ≤ 0.7 (y = 0), x ≤ 0.5 (y = 0.5), and x ≤ 0.1 (y = 1.0). The doped holes are received predominantly at the Mn-O site and change the charge of Mn from 3+ to 4+, and no superconductivity has been obtained for any sample. The electronic ground state of (Eu 3-x Ca x )Ba 2 (Mn 2-y Sc y )Cu 2 O 12 is discussed by comparing with that of the three-dimensional perovskite La 1-x Ca x MnO 3 and K 2 NiF 4 -type La 1-x Sr 1+x MnO 4 compounds. The substitution of Sr for Ba gives rise to a different crystal structure, the Sr 3 Ti 2 O 7 structure

Two-Dimensional Algal Collection and Assembly by Combining AC-Dielectrophoresis with Fluorescence Detection for Contaminant-Induced Oxidative Stress Sensing

Directory of Open Access Journals (Sweden)

Coralie Siebman

2015-06-01

Full Text Available An alternative current (AC dielectrophoretic lab-on-chip setup was evaluated as a rapid tool of capture and assembly of microalga Chlamydomonas reinhardtii in two-dimensional (2D close-packed arrays. An electric field of 100 V·cm−1, 100 Hz applied for 30 min was found optimal to collect and assemble the algae into single-layer structures of closely packed cells without inducing cellular oxidative stress. Combined with oxidative stress specific staining and fluorescence microscopy detection, the capability of using the 2D whole-cell assembly on-chip to follow the reactive oxygen species (ROS production and oxidative stress during short-term exposure to several environmental contaminants, including mercury, methylmercury, copper, copper oxide nanoparticles (CuO-NPs, and diuron was explored. The results showed significant increase of the cellular ROS when C. reinhardtii was exposed to high concentrations of methylmercury, CuO-NPs, and 10−5 M Cu. Overall, this study demonstrates the potential of combining AC-dielectrophoretically assembled two-dimensional algal structures with cell metabolic analysis using fluorescence staining, as a rapid analytical tool for probing the effect of contaminants in highly impacted environment.

Substrate type < 111 >-Cu{sub 2}O/<0001 >-ZnO photovoltaic device prepared by photo-assisted electrodeposition

Energy Technology Data Exchange (ETDEWEB)

Zamzuri, Mohd, E-mail: zamzuri@tf.me.tut.ac.jp [Department of Mechanical Eng., Toyohashi University of Technology, 1-1 Hibari Gaoka, Tempaku, Toyohashi, Aichi 441-8580 (Japan); School of Manufacturing Eng., Universiti Malaysia Perlis, Kampus Tetap Pauh Putra, Jln Arau-Changlun, 02600 Arau, Perlis (Malaysia); Sasano, Junji [Department of Mechanical Eng., Toyohashi University of Technology, 1-1 Hibari Gaoka, Tempaku, Toyohashi, Aichi 441-8580 (Japan); Mohamad, Fariza Binti [Faculty of Electrical & Electronic Eng., University Tun Hussein Onn Malaysia, 86400, Parit Raja, Batu Pahat, Johor (Malaysia); Izaki, Masanobu [Department of Mechanical Eng., Toyohashi University of Technology, 1-1 Hibari Gaoka, Tempaku, Toyohashi, Aichi 441-8580 (Japan)

2015-11-30

The substrate-type < 0001 > ZnO/<111 > Cu{sub 2}O photovoltaic (PV) device has been constructed by electrodeposition of a < 111 >-p-Cu{sub 2}O layer on an Au(111)/Si wafer substrate followed by stacking the n-ZnO layer by electrodeposition during light irradiation in aqueous solutions. The PV device was fabricated by stacking the Al:ZnO-window by sputtering and the top Al electrode by vacuum evaporation. The < 0001 >-ZnO layer was composed of aggregates of hexagonal columnar grains grown in the direction normal to the surface, and pores could be observed between the ZnO grains at the deposition time last 1800 s. The < 0001 >-ZnO/<111 >-Cu{sub 2}O PV device showed a photovoltaic performance under AM1.5 illumination, and showed the improved short-circuit current density of 5.87 mA cm{sup −2} by stacking the AZO-TCO due to the increase in the diffusion length of the carrier. - Highlights: • Substrate type ZnO/Cu{sub 2}O photovoltaic devices only by electrodeposition • ZnO layer was stacked on the Cu{sub 2}O layer by photo-assisted electrodeposition. • AZO/ZnO/Cu{sub 2}O photovoltaic devices with a short-circuit current density of 5.87 mA cm{sup −2}.

Momentum Dependence of Charge Excitations in YBa2Cu3O7-δ and Nd2-xCexCuO4

Science.gov (United States)

Ishii, Kenji

2006-03-01

Resonant inelastic x-ray scattering (RIXS) studies at Cu K-edge on high-Tc superconducting cuprates, YBa2Cu3O7-δ and Nd2-xCexCuO4 are presented. The superconductivity occurs in the vicinity of the Mott insulating state and it is important to clarify the nature of the Mott gap and its doping dependence. Because RIXS has an advantage that we can measure charge excitation in a wide energy-momentum space, it gives a unique opportunity to study the electronic structure of materials. We apply this technique to high-Tc superconducting cuprates. In particular the electronic structure of strongly correlated metals is in the focus of our RIXS study. The experiments were performed at BL11XU of SPring-8, Japan, where a specially designed spectrometer for inelastic x-ray scattering is installed. In optimally doped YBa2Cu3O7-δ, anisotropic spectra are observed in the ab plane of a twin-free crystal. The Mott gap excitation from the one-dimensional CuO chain is enhanced at 2 eV near the zone boundary of the chain direction, while the excitation from the CuO2 plane is broad at 1.5-4 eV and almost independent of momentum. Theoretical calculation based on the one-dimensional and two-dimensional Hubbard model reproduces the observed features in the RIXS spectra when smaller values of the on-site Coulomb energy of the chain than that of the plane are assumed. This means that the charge transfer gap of the chain is smaller than that of the plane. On the other hand, both interband excitation across the Mott gap and intraband excitation in the upper Hubbard band are observed in the electron-doped Nd2-xCexCuO4. The intensity of the interband excitation is concentrated at ˜ 2 eV near the zone boundary while a dispersion relation with a momentum-dependent width emerges in the intraband excitation. The author would like to acknowledge to his collaborators, K. Tsutsui, Y. Endoh, T. Tohyama, K. Kuzushita, T. Inami, K. Ohwada, M. Hoesch, M. Tsubota, Y. Murakami, J. Mizuki, S. Maekawa, T

Colloidal synthesis of Cu-ZnO and Cu@CuNi-ZnO hybrid nanocrystals with controlled morphologies and multifunctional properties

Science.gov (United States)

Zeng, Deqian; Gong, Pingyun; Chen, Yuanzhi; Zhang, Qinfu; Xie, Qingshui; Peng, Dong-Liang

2016-06-01

Metal-semiconductor hybrid nanocrystals have received extensive attention owing to their multiple functionalities which can find wide technological applications. The utilization of low-cost non-noble metals to construct novel metal-semiconductor hybrid nanocrystals is important and meaningful for their large-scale applications. In this study, a facile solution approach is developed for the synthesis of Cu-ZnO hybrid nanocrystals with well-controlled morphologies, including nanomultipods, core-shell nanoparticles, nanopyramids and core-shell nanowires. In the synthetic strategy, Cu nanocrystals formed in situ serve as seeds for the heterogeneous nucleation and growth of ZnO, and it eventually forms various Cu-ZnO hetero-nanostructures under different reaction conditions. These hybrid nanocrystals possess well-defined and stable heterostructure junctions. The ultraviolet-visible-near infrared spectra reveal morphology-dependent surface plasmon resonance absorption of Cu and the band gap absorption of ZnO. Furthermore, we construct a novel Cu@CuNi-ZnO ternary hetero-nanostructure by incorporating the magnetic metal Ni into the pre-synthesized colloidal Cu nanocrystals. Such hybrid nanocrystals possess a magnetic Cu-Ni intermediate layer between the ZnO shell and the Cu core, and exhibit ferromagnetic/superparamagnetic properties which expand their functionalities. Finally, enhanced photocatalytic activities are observed in the as-prepared non-noble metal-ZnO hybrid nanocrystals. This study not only provides an economical way to prepare high-quality morphology-controlled Cu-ZnO hybrid nanocrystals for potential applications in the fields of photocatalysis and photovoltaic devices, but also opens up new opportunities in designing ternary non-noble metal-semiconductor hybrid nanocrystals with multifunctionalities.Metal-semiconductor hybrid nanocrystals have received extensive attention owing to their multiple functionalities which can find wide technological applications

Improved resistive switching phenomena and mechanism using Cu-Al alloy in a new Cu:AlO{sub x}/TaO{sub x}/TiN structure

Energy Technology Data Exchange (ETDEWEB)

Roy, S. [Thin Film Nano Tech. Lab., Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kwei-Shan, Tao-Yuan 333, Taiwan (China); Maikap, S., E-mail: sidhu@mail.cgu.edu.tw [Thin Film Nano Tech. Lab., Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kwei-Shan, Tao-Yuan 333, Taiwan (China); Sreekanth, G.; Dutta, M.; Jana, D. [Thin Film Nano Tech. Lab., Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kwei-Shan, Tao-Yuan 333, Taiwan (China); Chen, Y.Y.; Yang, J.R. [Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan (China)

2015-07-15

Highlights: • Cu:AlO{sub x} alloy is used for the first time to have defective TaO{sub x} film. • A relation in between formation voltage and RESET current has been developed. • A switching mechanism based on a thinner with dense Cu filament is demonstrated. • Good uniformity with yield of >90% and long cycles using 1 ms pulse are obtained. - Abstract: Improved resistive switching phenomena such as device-to-device uniformity, lower formation voltage (2.8 V) and RESET current, >500 program/erase cycles, longer read endurance of >10{sup 6} cycles with a program/erase pulse width of 1 μs, and data retention of >225 h under a low current compliance of 300 μA have been discussed by using Cu-Al alloy in Cu:AlO{sub x}/TaO{sub x}/TiN conductive bridging resistive random access memory (CBRAM) device for the first time. The switching mechanism is based on a thinner with dense Cu filament formation/dissolution through the defects in the Cu:AlO{sub x}/TaO{sub x}/TiN structure owing to enhance memory characteristics. These characteristics have been confirmed by measuring randomly picked 100 devices having via-hole size of 0.4 × 0.4 μm{sup 2}. The Cu-Al alloy becomes Cu:AlO{sub x} buffer layer and Ta{sub 2}O{sub 5} becomes TaO{sub x} switching layer owing to Gibbs free energy dependency. All layers and elements are observed by high-resolution transmission electron microscope (HRTEM) image and energy dispersive X-ray spectroscopy (EDX). By developing a numerical equation in between RESET current and formation voltage, it is found that a higher rate of Cu migration is observed owing to both the defective switching layer and larger size, which results a lower formation voltage and RESET current of the Cu:AlO{sub x}/TaO{sub x}/TiN structure, as compared to Cu/Ta{sub 2}O{sub 5}/TiN under external positive bias on the Cu electrode. This simple Cu:AlO{sub x}/TaO{sub x}/TiN CBRAM device is useful for future nanoscale non-volatile memory application.

Search for a nematic phase in the quasi-two-dimensional antiferromagnet CuCrO2 by NMR in an electric field

Science.gov (United States)

Sakhratov, Yu. A.; Kweon, J. J.; Choi, E. S.; Zhou, H. D.; Svistov, L. E.; Reyes, A. P.

2018-03-01

The magnetic phase diagram of CuCrO2 was studied with an alternative method of simultaneous Cu NMR and electric polarization techniques with the primary goal of demonstrating that, regardless of cooling history of the sample, the magnetic phase with specific helmet-shaped NMR spectra associated with interplanar disorder possesses electric polarization. Our result unequivocally confirms the assumption of Sakhratov et al. [Phys. Rev. B 94, 094410 (2016), 10.1103/PhysRevB.94.094410] that the high-field low-temperature phase is in fact a three-dimensional (3D) polar phase characterized by a 3D magnetic order with tensor order parameter. In comparison with the results obtained in pulsed fields, a modified phase diagram is introduced defining the upper boundary of the first-order transition from the 3D spiral to the 3D polar phase.

Evidence for the quasi-two dimensional behavior of the vortex structure in Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8] single crystals

Energy Technology Data Exchange (ETDEWEB)

Pastoriza, H [Comision Nacional de Energia Atomica, Centro Atomico Bariloche (Argentina); Arribere, A [Comision Nacional de Energia Atomica, Centro Atomico Bariloche (Argentina); Goffman, M F [Comision Nacional de Energia Atomica, Centro Atomico Bariloche (Argentina); Cruz, F de la [Comision Nacional de Energia Atomica, Centro Atomico Bariloche (Argentina); Mitzi, D B [Dept. of Applied Physics, Stanford Univ., CA (United States); Kapitulnik, A [Dept. of Applied Physics, Stanford Univ., CA (United States)

1994-02-01

AC susceptibility and dc magnetization measurements on Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8] (BSCCO) single crystals in a wide range of temperatures clearly show that below the dc irreversibility line the vortex system loss the long range order in the c direction. The susceptibility data taken at 7 Hz show the different nature of two dissipation peaks: One related to the interplane currents at temperatures well below the dc irreversibility line and the other associated with the intraplane ones at temperatures above that line. In this sense the irreversibility line corresponds to the temperature where quasi-two dimensional vortices are depinned. (orig.)

Layered Cu-based electrode for high-dielectric constant oxide thin film-based devices

International Nuclear Information System (INIS)

Fan, W.; Saha, S.; Carlisle, J.A.; Auciello, O.; Chang, R.P.H.; Ramesh, R.

2003-01-01

Ti-Al/Cu/Ta multilayered electrodes were fabricated on SiO 2 /Si substrates by ion beam sputtering deposition, to overcome the problems of Cu diffusion and oxidation encountered during the high dielectric constant (κ) materials integration. The Cu and Ta layers remained intact through the annealing in oxygen environment up to 600 deg. C. The thin oxide layer, formed on the Ti-Al surface, effectively prevented the oxygen penetration toward underneath layers. Complex oxide (Ba x Sr 1-x )TiO 3 (BST) thin films were grown on the layered Ti-Al/Cu/Ta electrodes using rf magnetron sputtering. The deposited BST films exhibited relatively high permittivity (150), low dielectric loss (0.007) at zero bias, and low leakage current -8 A/cm 2 at 100 kV/cm

Faceting of (001) CeO2 Films: The Road to High Quality TFA-YBa2Cu3O7 Multilayers

International Nuclear Information System (INIS)

Coll, M; Gazquez, J; Sandiumenge, F; Pomar, A; Puig, T; Obradors, X; Espinos, J P; Gonzalez-Elipe, A R

2006-01-01

CeO 2 films are technologically important as a buffer layer for the integration of superconducting YBa 2 Cu 3 O 7 films on biaxially textured Ni substrates. The growth of YBa 2 Cu 3 O 7 layers on the CeO 2 cap layers by the trifluoroacetate (TFA) route remains a critical issue. To improve the accommodation of YBa 2 Cu 3 O 7 on CeO 2 , surface conditioning or CeO 2 is required. In this work we have applied ex-situ post-processes at different atmospheres to the CeO 2 layers deposited on YSZ single crystals using rf sputtering. XPS analysis showed that post-annealing CeO 2 layer in Ar/H 2 /H 2 O catalyses in an unexpected way the growth of (001)- terraces. We also report on the growth conditions of YBa 2 Cu 3 O 7 -TFA on CeO 2 buffered YSZ single crystal grown by chemical solution deposition and we compare them with those leading to optimized YBa 2 Cu 3 O 7 -TFA films on LaAlO 3 single crystals. Critical currents up to 1.6 MA/cm 2 at 77 K have been demonstrated in 300 nm thick YBa 2 Cu 3 O 7 layers on CeO 2 /YSZ system. The optimized processing conditions have then been applied to grow YBa 2 Cu 3 O 7 -TFA films on Ni substrates having vacuum deposited cap layers of CeO 2

Bi-epitaxial YBa{sub 2}Cu{sub 3}O{sub x} Thin Films on Tilted-axes NdGaO{sub 3} Substrates with CeO{sub 2} Seeding Layer

Energy Technology Data Exchange (ETDEWEB)

Mozhaev, P B [Institute of Physics and Technology RAS, 117218, Moscow (Russian Federation); Mozhaeva, J E [Institute of Physics and Technology RAS, 117218, Moscow (Russian Federation); Jacobsen, C S [Technical University of Denmark, Physics Department, Lyngby, DK-2800, Denmark (Denmark); Hansen, J Bindslev [Technical University of Denmark, Physics Department, Lyngby, DK-2800, Denmark (Denmark); Bdikin, I K [CICECO, University of Aveiro, Aveiro, 3810-193 (Portugal); Luzanov, V A [Institute of Radio Engineering and Electronics, Moscow, 125009 (Russian Federation); Kotelyanskii, I M [Institute of Radio Engineering and Electronics, Moscow, 125009 (Russian Federation); Zybtsev, S G [Institute of Radio Engineering and Electronics, Moscow, 125009 (Russian Federation)

2006-06-01

Bi-epitaxial YBa{sub 2}Cu{sub 3}O{sub x} (YBCO) thin films with out-of-plane tilt angle in the range 18 - 27{sup 0} were manufactured using pulsed laser deposition on NdGaO{sub 3} tilted-axes substrates with CeO{sub 2} seeding layers. The YBCO thin film orientation over the seeding layer depended on deposition conditions. Removal of the seeding layer from part of the substrate surface by ionbeam etching resulted in formation of a bi-epitaxial thin film with different c-axis orientation of two parts of the film. The bi-epitaxial film orientation and structure were studied using X-ray diffraction techniques, and surface morphology was observed with atomic force microscope (AFM). Photolithography and ion-beam etching techniques were used for patterning bi-epitaxial thin films. Electrical characterization of the obtained structures was performed.

Synthesis and characterization of ZnO/Cu{sub 2}O core–shell nanowires grown by two-step electrodeposition method

Energy Technology Data Exchange (ETDEWEB)

Messaoudi, O., E-mail: olfamassaoudi@gmail.com [Laboratoire de Photovoltaïque, Centre de Recherches et des Technologies de l’Energie, Technopole Borj Cedria, B.P. 95, Hammam Lif, 2050 (Tunisia); Makhlouf, H.; Souissi, A.; Ben assaker, I. [Laboratoire de Photovoltaïque, Centre de Recherches et des Technologies de l’Energie, Technopole Borj Cedria, B.P. 95, Hammam Lif, 2050 (Tunisia); Amiri, G. [Groupe d’Etude de la Matière Condensée, CNRS Université de Versailles Saint Quentin (France); Bardaoui, A. [Laboratoire de Photovoltaïque, Centre de Recherches et des Technologies de l’Energie, Technopole Borj Cedria, B.P. 95, Hammam Lif, 2050 (Tunisia); Physics Department, Taif University (Saudi Arabia); Oueslati, M. [Unité Nanomatériaux et Photonique, Faculté Des Sciences de Tunis, Campus Universitaire El Manar, 2092, Tunis (Tunisia); Bechelany, M. [European Institute of Membranes (IEM ENSCM UM2 CNRS UMR 5635), University of Montpellier 2, 34095 Montpellier (France); Chtourou, R. [Laboratoire de Photovoltaïque, Centre de Recherches et des Technologies de l’Energie, Technopole Borj Cedria, B.P. 95, Hammam Lif, 2050 (Tunisia)

2015-07-15

Highlights: • ZnO/Cu{sub 2}O core/shell nanowires have been grown by two-step electrodeposition method. • SEM confirmed the homogenous distribution of Cu{sub 2}O on the deposited nanowires. • The X-ray diffraction demonstrated that the films were pure. • Optical transmissions measurements reveal an additional contribution at about 1.7 eV. • The ZnO/Cu{sub 2}O structure is expected to have an advantage in photovoltaic application. - Abstract: ZnO/Cu{sub 2}O core/shell nanowires have been grown by two-step electrodeposition method on ITO-coated glass substrates. The sample's morphology was explored by means of scanning electron microscopy (SEM). SEM images confirm the homogeneity of the nanowires and the presence of Cu{sub 2}O shell on ZnO core. X-ray diffraction and Raman scattering measurements were used to investigate the purity and the crystallinity of the samples. Optical transmission measurements reveal an additional contribution at about 1.7 eV attributed to the type-II interfacial transition witch confirms the advantage of using the ZnO/Cu{sub 2}O structure in photovoltaic application.

Development of a Low-Cost TiO2/CuO/Cu Solar Cell by using Combined Spraying and Electroplating Method

Directory of Open Access Journals (Sweden)

Mamat Rokhmat

2018-03-01

Full Text Available A simple method is proposed to develop a low-cost TiO2/CuO/Cu based solar cell. The cell is made by employing a lower grade (technical grade of TiO2 as the active material. CuO powder is synthesized using a wet chemical method and mixed with TiO2 powder to give impurity to the TiO2. A layer of TiO2/CuO is then deposited onto fluorin-doped tin oxide (FTO by spraying. Copper particles are grown on the spaces between the TiO2 and/or CuO particles by electroplating for more feasible electron migration. The TiO2/CuO/Cu solar cell is finalized by sandwiching a polymer electrolyte between the film and the counter electrode. Current-voltage measurement was performed for various parameters, such as the molarity of NaOH for producing CuO particles, the weight ratio of CuO over TiO2, and the current in the electroplating process. A highest efficiency of 1.40% and a fill factor of 0.37 were achieved by using this combined spray and electroplating method.

Temperature dependence of positron lifetime in the two-mixed-phase Bi-Sr-Ca-Cu-O superconductor

International Nuclear Information System (INIS)

Zhang, D.M.; Tang, C.Q.; Gen, T.; Li, G.Y.

1993-01-01

As compared with the YBaCuO(123) system, the studies of positron annihilation performed for other cuprate superconductors, specifically for the BiSrCaCuO and TlBaCa.CuO systems, are very few. Thus further study of positron annihilation in BiSrCaCuO and TlBaCaCuO systems is necessary. In this note, we report the results of the temperature dependence of positron lifetime parameters in the two-mixed-phase system BiSrCaCuO and discuss the results. (orig.)

Anisotropy and dimensional characteristics in CVD route Y1Ba2Cu3O7-δ

International Nuclear Information System (INIS)

Watanabe, K.; Kobayashi, N.; Awaji, S.; Yamane, H.; Hirai, T.; Muto, Y.

1993-01-01

The anisotropic behaviors of the upper critical field B c2 and the critical current density J c were investigated in Y 1 Ba 2 Cu 3 O 7-δ films prepared by a chemical vapor deposition (CVD) route. The angular dependence of J c at fixed temperature, the field dependence of J c at fixed angle, and the temperature dependence of J c at fixed field were measured. The obtained results were explored in terms of the dimensional superconducting characteristics. The important information on the anisotropic behaviors of J c in CVD-Y 1 Ba 2 Cu 3 O 7-δ was discussed from a viewpoint of the flux pinning. (orig.)

Layered SmBaCuCoO5+δ and SmBaCuFeO5+δ perovskite oxides as cathode materials for proton-conducting SOFCs

International Nuclear Information System (INIS)

Nian Qiong; Zhao Ling; He Beibei; Lin Bin; Peng Ranran; Meng Guangyao; Liu Xingqin

2010-01-01

A dense BaCe 0.8 Sm 0.2 O 5+δ (BCS) electrolyte was fabricated on a porous anode by in situ drop-coating to develop a simple and cost-effective route to fabricate proton-conducting solid oxide fuel cells (SOFCs). Layered perovskite-structure oxides SmBaCuCoO 5+δ (SBCC) and SmBaCuFeO 5+δ (SBCF) were prepared and the electrical conductivity, the thermal expansion coefficient and electrochemical performance were investigated as potential cathode materials for proton-conducting SOFCs. Thermal expansion coefficients of SBCC and SBCF were suitable for BCS electrolyte and the electrical conductivity of the SBCC is higher than that of the SBCF. The maximum power density of 449 mW cm 2 and 333 mW cm 2 at 700 o C were obtained for the SBCC/BCS/NiO-BCS and SBCF/BCS/NiO-BCS cells, respectively. The interfacial polarization resistances for SBCC and SBCF cathode are as low as 0.137 Ω cm -2 and 0.196 Ω cm -2 at 700 o C, respectively. The results indicate that the SBCC and SBCF are promising cathode materials for proton-conducting SOFCs.

Role of BaO/SrO layers in deciding the electronic structure of Cu0.3Co0.7Ba2-xSrxYCu2O7+δ (CoCu-1212) x = 0, 1 and 2

International Nuclear Information System (INIS)

Singh, Shiva Kumar; Husain, M.; Kishan, H.; Awana, V.P.S.

2011-01-01

Highlights: → Decrease in lattice parameters confirms replacement by Sr ion at Ba ion site. → XPS measurement shows that mixed Cu 1+/2+ and Co 3+/4+ valence state. → With increasing x, Cu valence is non-monotonous whereas Co valence is increasing. → Resistivity reveals that holes in Cu/CoO x planes are taking part in charge transport. → Paramagnetic nature is due to the presence Cu ions in Cu/CoO x chains/planes. - Abstract: In this paper we report the change in electronic structure of Cu 0.3 Co 0.7 Ba 2-x Sr x YCu 2 O 7+δ with change in structural pressure. Rietveld refined X-ray diffraction (XRD) pattern shows that the samples are phase pure. Decrease in lattice parameters with increasing x, confirms replacement by Sr ion at Ba ion site. The calculated tolerance factor of the systems is in accord with lattice parameter changes. The X-ray photoelectron spectroscopy (XPS) is made to find out the variation in ionic state of Co and Cu with ionic size variation in BaO/SrO layers. Effect of the same on the electronic structure and transport properties is explored. The XPS measurement reveals that Cu is in mixed 1+/2+ state and variation in valence state is non-monotonous with increasing x. Whereas Co is in mixed 3+/4+ state and with increasing x its valence state is increasing. The observed changes in electronic structure are subject of structural changes. The resistivity measurement shows that normal state conductivity decreases with increasing x. Resistivity behaviour indicates about holes in Cu/CoO x planes taking part in charge transport. The magnetic measurement (M-T and M-H) shows that paramagnetic nature for all the compositions. The presence of Cu ions in Cu/CoO x chains/planes results in paramagnetic behaviour.

Polarity driven morphology of CeO2(1 0 0) islands on Cu(1 1 1)

International Nuclear Information System (INIS)

Stetsovych, O.; Beran, J.; Dvořák, F.; Mašek, K.; Mysliveček, J.; Matolín, V.

2013-01-01

Thin ceria films supported by metal substrates represent important model systems for reactivity studies in heterogeneous catalysis. Here we report the growth study of the polar CeO 2 (1 0 0) phase as part of a mixed CeO 2 (1 1 1)–CeO 2 (1 0 0) thin film supported by Cu(1 1 1). The two ceria phases grow on different areas of the substrate, what allows a reliable growth characterization of the CeO 2 (1 0 0) islands on Cu(1 1 1). Scanning tunneling microscopy measurements reveal CeO 2 (1 0 0) to grow in the form of highly dispersed three dimensional (3D) islands on a CeO 2 (1 0 0) interfacial layer. The CeO 2 (1 0 0) islands exhibit a 2 × 2 surface reconstruction. The presence of the surface reconstruction together with the highly dispersed growth of CeO 2 (1 0 0) islands corresponds to the requirement for compensation of the surface dipole moment on the CeO 2 (1 0 0). CeO 2 (1 0 0) islands are further characterized by reflection high energy electron diffraction yielding their epitaxial relations with respect to the Cu(1 1 1) substrate. The growth of well characterized CeO 2 (1 0 0) islands supported by Cu(1 1 1) represents a starting point for developing a novel template for structure-related reactivity studies of ceria based model catalysts.

Anomalies of temperature dependence of the upper critical magnetic field of GdBa2Cu3O7-x and their relation with layered crystal structure

International Nuclear Information System (INIS)

Anshukova, N.V.; Veselago, V.G.; Golovashkin, A.I.

1989-01-01

Temperature dependence of upper critical field H c2 (T) near T c was investigated on polycrystal GdBa 2 Cu 3 O 7-x . The resistive superconductive transitions were measured in magnetic fields up to 15 T. We observed a magnetic-field induced broadening of transition and an appearance of H c2 (T) nonlinearity near T c and explained such effects by the influence of individual grains H c2 anisotropy on the base of the percolation model. Estimated are slopes: for magnetic field along superconductive layers -dH c2 parallel /dT≅ 7T/K and for field across layers -dH c2 tr /dT=0.2 T/K. It was found that H c2 (T)-curves display anomalies in a break form, which were not explained in the percolation model. The across coherence length ξ tr (T) obtained from values of the slopes was comparable with distance d between two superconductive layers. So we think that in this situation a fracture on the H c2 (T)-curves may be explained by the appearance of electronic density nonuniformity and it is precursor of crossover to two-dimensional superconductivity

Chemical-bath ZnO buffer layer for CuInS{sub 2} thin-film solar cells

Energy Technology Data Exchange (ETDEWEB)

Ennaoui, A.; Weber, M.; Scheer, R.; Lewerenz, H.J. [Hahn-Meitner-Institut, Abt. Grenzflaechen, Bereich Physikalische Chemie, Glienicker Strasse 100, D-14109 Berlin (Germany)

1998-07-13

ZnO buffer layers were grown by a chemical-bath deposition (CBD) in order to improve the interface quality in p-CuInS{sub 2} based solar cells, to improve the light transmission in the blue wavelength region, but also as an alternative to eliminate the toxic cadmium. The process consists of immersion of different substrates (glass, CIS) in a dilute solution of tetraamminezinc II, [Zn(NH{sub 2}){sub 4}]{sup 2+}, complex at 60-95C. During the growth process, a homogeneous growth mechanism which proceeds by the sedimentation of a mixture of ZnO and Zn(OH){sub 2} clusters formed in solution, competes with the heterogeneous growth mechanism. The mechanism consists of specific adsorption of a complex Zn(II) followed by a chemical reaction. The last process of growth results in thin, hard, adherent and specularly reflecting films. The characterization of the deposited CBD-ZnO layers was performed by X-ray diffraction (XRD), optical transmittance, scanning electron microscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The as-deposited films on glass show hexagonal zincite structure with two preferred orientations (1 0 0) and (1 0 1). High optical transmittance up to 80% in the near-infrared and part of the visible region was observed. The low growth rate of the films on CIS suggests an atomic layer-by-layer growth process.The device parameters and performance are compared to heterojunction with a standard CdS buffer layer

CuO reduction induced formation of CuO/Cu2O hybrid oxides

Science.gov (United States)

Yuan, Lu; Yin, Qiyue; Wang, Yiqian; Zhou, Guangwen

2013-12-01

Reduction of CuO nanowires results in the formation of a unique hierarchical hybrid nanostructure, in which the parent oxide phase (CuO) works as the skeleton while the lower oxide (Cu2O) resulting from the reduction reaction forms as partially embedded nanoparticles that decorate the skeleton of the parent oxide. Using in situ transmission electron microscopy observations of the reduction process of CuO nanowires, we demonstrate that the formation of such a hierarchical hybrid oxide structure is induced by topotactic nucleation and growth of Cu2O islands on the parent CuO nanowires.

New hybrid lead iodides: From one-dimensional chain to two-dimensional layered perovskite structure

International Nuclear Information System (INIS)

Xiong, Kecai; Liu, Wei; Teat, Simon J.; An, Litao; Wang, Hao; Emge, Thomas J.; Li, Jing

2015-01-01

Two new hybrid lead halides (H 2 BDA)[PbI 4 ] (1) (H 2 BDA=1,4-butanediammonium dication) and (HNPEIM)[PbI 3 ] (2) (HNPEIM=N-​phenyl-ethanimidamidine cation) have been synthesized and structurally characterized. X-ray diffraction analyses reveal that compound 1 features a two-dimensional corner-sharing perovskite layer whereas compound 2 contains one-dimensional edge-sharing double chains. The N-​phenyl-ethanimidamidine cation within compound 2 was generated in-situ under solvothermal conditions. The optical absorption spectra collected at room temperature suggest that both compounds are semiconductors having direct band gaps, with estimated values of 2.64 and 2.73 eV for 1 and 2, respectively. Results from the density functional theory (DFT) calculations are consistent with the experimental data. Density of states (DOS) analysis reveals that in both compounds 1 and 2, the energy states in the valence band maximum region are iodine 5p atomic orbitals with a small contribution from lead 6s, while in the region of conduction band minimum, the major contributions are from the inorganic (Pb 6p atomic orbitals) and organic components (C and N 2p atomic orbitals) in compound 1 and 2, respectively. - Graphical abstract: Two new hybrid lead halides built on one-dimensional edge-sharing double chains and two-dimensional corner-sharing perovskite layers are synthesized and their structural and electronic properties are analyzed. - Highlights: • Two new hybrid lead iodides are designed, synthesized, and characterized. • They are closely related to, but different from, perovskite structures. • The electronic properties of both compounds are analyzed by DFT calculations

New hybrid lead iodides: From one-dimensional chain to two-dimensional layered perovskite structure

Energy Technology Data Exchange (ETDEWEB)

Xiong, Kecai; Liu, Wei [Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854 (United States); Teat, Simon J. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); An, Litao; Wang, Hao; Emge, Thomas J. [Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854 (United States); Li, Jing, E-mail: jingli@rutgers.edu [Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854 (United States)

2015-10-15

Two new hybrid lead halides (H{sub 2}BDA)[PbI{sub 4}] (1) (H{sub 2}BDA=1,4-butanediammonium dication) and (HNPEIM)[PbI{sub 3}] (2) (HNPEIM=N-​phenyl-ethanimidamidine cation) have been synthesized and structurally characterized. X-ray diffraction analyses reveal that compound 1 features a two-dimensional corner-sharing perovskite layer whereas compound 2 contains one-dimensional edge-sharing double chains. The N-​phenyl-ethanimidamidine cation within compound 2 was generated in-situ under solvothermal conditions. The optical absorption spectra collected at room temperature suggest that both compounds are semiconductors having direct band gaps, with estimated values of 2.64 and 2.73 eV for 1 and 2, respectively. Results from the density functional theory (DFT) calculations are consistent with the experimental data. Density of states (DOS) analysis reveals that in both compounds 1 and 2, the energy states in the valence band maximum region are iodine 5p atomic orbitals with a small contribution from lead 6s, while in the region of conduction band minimum, the major contributions are from the inorganic (Pb 6p atomic orbitals) and organic components (C and N 2p atomic orbitals) in compound 1 and 2, respectively. - Graphical abstract: Two new hybrid lead halides built on one-dimensional edge-sharing double chains and two-dimensional corner-sharing perovskite layers are synthesized and their structural and electronic properties are analyzed. - Highlights: • Two new hybrid lead iodides are designed, synthesized, and characterized. • They are closely related to, but different from, perovskite structures. • The electronic properties of both compounds are analyzed by DFT calculations.

Crystal structure and characterization of a novel layered copper-lithium phosphonate with antiferromagnetic intrachain Cu(II)···Cu(II) interactions

Energy Technology Data Exchange (ETDEWEB)

Abdelbaky, Mohammed S.M. [Departments of Physical and Analytical Chemistry and Organic and Inorganic Chemistry, University of Oviedo-CINN, 33006 Oviedo (Spain); Amghouz, Zakariae [Scientific and Technical Services, University of Oviedo-CINN, 33006 Oviedo (Spain); Department of Materials Science and Metallurgical Engineering, University of Oviedo, Campus Universitario, 33203 Gijón (Spain); Blanco, David Martínez [Scientific and Technical Services, University of Oviedo-CINN, 33006 Oviedo (Spain); García-Granda, Santiago; García, José R. [Departments of Physical and Analytical Chemistry and Organic and Inorganic Chemistry, University of Oviedo-CINN, 33006 Oviedo (Spain)

2017-04-15

Novel metal phosphonate [CuLi(PPA)] [H{sub 3}PPA=3-phosphonopropionic acid] was synthesized hydrothermally and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, scanning electron microscopy, infrared spectroscopy, and thermogravimetric analysis. It crystallizes in the space group C2/c, with cell parameters a=21.617(2) Å, b=4.9269(2) Å, c=14.342(1) Å, β=132.3(2)°, and Z=8. Its framework is built up from a main trimer, acting as a secondary building unit (SBU), which is formed by vertex-shared between two (LiO{sub 4}) and one (Cu(1)O{sub 4}) polyhedra. These units repeat along b-axis forming infinite inorganic chains, these chains are in turn cross-linked by corner sharing with (Cu(2)O{sub 4}) polyhedra to produce inorganic layers lying in the bc-plane. The neighboring layers are connected through the PPA ligand, leading to a 3D pillared-layered structure. The topological analysis reveals that the compound exhibits 3,4,10-c net. Finally, magnetic susceptibility measurement of this compound over the temperature range of 2–300 K reveals the occurrence of weak antiferromagnetic intrachain interactions. - Graphical abstract: Hydrothermal synthesis and structural characterization of a novel lithium-copper phosphonate, formulated as [CuLi(PPA)] (H{sub 3}PPA=3-phosphonopropionic acid), have been reported. This compound has a 3D pillared-layered structure with 3,4,10-c net topology. The magnetic susceptibility data over the temperature range of 2–300 K reveals the occurrence of weak antiferromagnetic interactions. - Highlights: • Novel metal phosphonate, [CuLi(PPA)] (1), has been synthesized and characterized. • Compound 1 has a 3D pillared-layered structure with 3,4,10-c net topology. • Magnetic susceptibility data reveals the occurrence of weak antiferromagnetic interactions.

Angle-dependent reversible and irreversible magnetic torque in single-crystalline Y2Ba4Cu8O16

International Nuclear Information System (INIS)

Zech, D.; Rossel, C.; Lesne, L.; Keller, H.; Lee, S.L.; Karpinski, J.

1996-01-01

A systematic study of the angle-dependent reversible and irreversible magnetic torque in single-crystalline Y 2 Ba 4 Cu 8 O 16 is presented. The high purity of the crystals allows us to show some intrinsic pinning properties of vortices due to the layered crystal structure. The irreversible component of the torque, which is unusually small, exhibits a peculiar angular dependence: It is minimal as the magnetic field B is applied along the ab plane and displays a pronounced maximum at finite angles, reminiscent of the open-quote open-quote fishtail close-quote close-quote effect. The unusual shape of the irreversible torque is attributed to the pinning of the vortex core, which becomes discontinuous below the two- to three-dimensional (2D-3D) crossover temperature. Another property shown by the angle-dependent torque is the lock-in of the vortex lines between the CuO 2 layers for B parallel to the ab plane. Applying the anisotropic 3D London model to fit the reversible torque data, we derive the in-plane London penetration depth λ ab =143 nm, the coherence length ξ ab =1.9 nm, and the effective mass anisotropy ratio γ=12.3 for Y 2 Ba 4 Cu 8 O 16 . copyright 1996 The American Physical Society

Preparation of Cu@Cu2O Nanocatalysts by Reduction of HKUST-1 for Oxidation Reaction of Catechol

Directory of Open Access Journals (Sweden)

Seongwan Jang

2016-11-01

Full Text Available HKUST-1, a copper-based metal organic framework (MOF, has been investigated as a catalyst in various reactions. However, the HKUST-1 shows low catalytic activity in the oxidation of catechol. Therefore, we synthesized Fe3O4@HKUST-1 by layer-by layer assembly strategy and Cu@Cu2O by reduction of HKUST-1 for enhancement of catalytic activity. Cu@Cu2O nanoparticles exhibited highly effective catalytic activity in oxidation of 3,5-di-tert-butylcatechol. Through this method, MOF can maintain the original core-shell structure and be used in various other reactions with enhanced catalytic activity.

Superconductivity at 108 K in the simplest non-toxic double-layer cuprate of Ba2CaCu2O4(O,F)2

International Nuclear Information System (INIS)

Shirage, P M; Shivagan, D D; Crisan, A; Tanaka, Y; Kodama, Y; Kito, H; Iyo, A

2008-01-01

We report the superconductivity in apical fluorine system of Ba 2 CaCu 2 O 6-y F y : the second member of Ba 2 Ca n-1 Cu n O 2n (O,F) 2 homologous series. The polycrystalline samples of Ba 2 CaCu 2 O 6-y F y (F-0212) were synthesized under high pressure as a parameter of nominal fluorine content (y). Samples with y = 2.0 ∼ 1.2 elucidating the very sharp superconducting transitions in temperature dependence of susceptibility from under doping state to slightly over doping state via optimal doping state. A remarkable highest T c of 108 K has been achieved for the sample synthesized from a nominal composition of Ba 2 CaCu 2 O 4.4 F 1.6 . This T c is highest among the double CuO 2 layered system except for that including toxic elements such as Hg and T1. The T c has been systematically controlled from 57 K to 108 K by controlling the doping state, by designing the starting composition of fluorine and oxygen. The strong dependence of the 'a' and 'c' lattice constants were found on the nominal F content. We propose the Ba 2 CaCu 2 O 4 (O,F) 2 as a promising material for practical use due to its high T c and non-toxicity with a simple crystal structure

Transport properties of YBa2Cu3O7/PrBa2Cu3O7 superlattices

International Nuclear Information System (INIS)

Jakob, G.; Hahn, T.; Stoelzel, C.; Tome-Rosa, C.; Adrian, H.

1992-01-01

We investigated the transport properties of high-quality YBa 2 Cu 3 O 7 /PrBa 2 Cu 3 O 7 superlattices. The exceptional structural order of the superlattices resulted in satellite peaks up to the ninth order in X-ray diffraction diagrams and high Tc values. We find high superconducting critical transport current densities j c even for ultrafine modulated superlattices which proves the existence of nearly continuous YBa 2 Cu 3 O 7 layers. The activation energy U is found to be constant or to have a linear temperatures dependence over a wide temperature range. (orig.)

Tuning the two-dimensional electron liquid at oxide interfaces by buffer-layer-engineered redox reactions

DEFF Research Database (Denmark)

Chen, Yunzhong; Green, Robert J.; Sutarto, Ronny

2017-01-01

Polar discontinuities and redox reactions provide alternative paths to create two-dimensional electron liquids (2DELs) at oxide interfaces. Herein, we report high mobility 2DELs at interfaces involving SrTiO3 (STO) achieved using polar La7/8Sr1/8MnO3 (LSMO) buffer layers to manipulate both...... polarities and redox reactions from disordered overlayers grown at room temperature. Using resonant x-ray reflectometry experiments, we quantify redox reactions from oxide overlayers on STO as well as polarity induced electronic reconstruction at epitaxial LSMO/STO interfaces. The analysis reveals how...... these effects can be combined in a STO/LSMO/disordered film trilayer system to yield high mobility modulation doped 2DELs, where the buffer layer undergoes a partial transformation from perovskite to brownmillerite structure. This uncovered interplay between polar discontinuities and redox reactions via buffer...

A two-dimensional Zn coordination polymer with a three-dimensional supra-molecular architecture.

Science.gov (United States)

Liu, Fuhong; Ding, Yan; Li, Qiuyu; Zhang, Liping

2017-10-01

The title compound, poly[bis-{μ 2 -4,4'-bis-[(1,2,4-triazol-1-yl)meth-yl]biphenyl-κ 2 N 4 : N 4' }bis-(nitrato-κ O )zinc(II)], [Zn(NO 3 ) 2 (C 18 H 16 N 6 ) 2 ] n , is a two-dimensional zinc coordination polymer constructed from 4,4'-bis-[(1 H -1,2,4-triazol-1-yl)meth-yl]-1,1'-biphenyl units. It was synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. The Zn II cation is located on an inversion centre and is coordinated by two O atoms from two symmetry-related nitrate groups and four N atoms from four symmetry-related 4,4'-bis-[(1 H -1,2,4-triazol-1-yl)meth-yl]-1,1'-biphenyl ligands, forming a distorted octa-hedral {ZnN 4 O 2 } coordination geometry. The linear 4,4'-bis-[(1 H -1,2,4-triazol-1-yl)meth-yl]-1,1'-biphenyl ligand links two Zn II cations, generating two-dimensional layers parallel to the crystallographic (132) plane. The parallel layers are connected by C-H⋯O, C-H⋯N, C-H⋯π and π-π stacking inter-actions, resulting in a three-dimensional supra-molecular architecture.

Impact of the deposition conditions of buffer and windows layers on lowering the metastability effects in Cu(In,Ga)Se2/Zn(S,O)-based solar cell

Science.gov (United States)

Naghavi, Negar; Hildebrandt, Thibaud; Bouttemy, Muriel; Etcheberry, Arnaud; Lincot, Daniel

2016-02-01

The highest and most reproducible (Cu(In,Ga)Se2 (CIGSe) based solar-cell efficiencies are obtained by use of a very thin n-type CdS layer deposited by chemical bath deposition (CBD). However because of both Cadmium's adverse environmental impact and the narrow bandgap of CdS (2.4-2.5 eV) one of the major objectives in the field of CIGSe technology remains the development and implementation in the production line of Cd-free buffer layers. The CBDZn( S,O) remains one the most studied buffer layer for replacing the CdS in Cu(In,Ga)Se2-based solar cells and has already demonstrated its potential to lead to high-efficiency solar cells up to 22.3%. However one of the key issue to implement a CBD-Zn(S,O) process in a CIGSe production line is the cells stability, which depends both on the deposition conditions of CBD-Zn(S,O) and on a good band alignment between CIGSe/Zn(S,O)/windows layers. The most common window layers applied in CIGSe solar cells consist of two layers : a thin (50-100 nm) and highly resistive i-ZnO layer deposited by magnetron sputtering and a transparent conducting 300-500 nm ZnO:Al layer. In the case of CBD-Zn(S,O) buffer layer, the nature and deposition conditions of both Zn(S,O) and the undoped window layer can strongly influence the performance and stability of cells. The present contribution will be specially focused on the effect of condition growth of CBD-Zn(S,O) buffer layers and the impact of the composition and deposition conditions of the undoped window layers such as ZnxMgyO or ZnxSnyO on the stability and performance of these solar cells.

Structure analysis of mutually incommensurate composite crystal (Ca0.5Y0.5)0.8CuO2

International Nuclear Information System (INIS)

Gotoh, Y.; Yamaguchi, I.; Takeya, S.; Fujihisa, H.; Honda, K.; Ito, T.; Oka, K.; Yamaguchi, H.

2006-01-01

Single-crystal X-ray structure analysis of mutually incommensurate (Ca 0.5 Y 0.5 ) 0.8 CuO 2 , 'Ca 2 Y 2 Cu 5 O 1 ' has been performed by the composite approach which leads to average substructures and their relative arrangement. The composite crystal structure of (Ca 0.5 Y 0.5 ) 0.8 CuO 2 has the CuO 2 substructure and the Ca 0.5 Y 0.5 substructure. The CuO 2 substructure with a 1 = 10.598(2) A, b = 6.189(2) A, c 1 = 2.825(2) A, β 1 = 90.19(4) o , V 1 = 185.4(1) A 3 , Z = 4 and space group F2/m has the plane of edge-shared one-dimensional CuO 2 chains along the c-axis. The Ca 0.5 Y 0.5 substructure with a 2 = 10.629(2) A, b = 6.189(2) A, c 2 3.517(1) A, β 2 = 94.36(3) o , V 2 = 230.7(1) A 3 , Z = 4 and space group F2/m forms the sheet of (Ca, Y) atoms in the ac-plane. By considering (3 + 1)-dimensional superspace group symmetry, it is concluded that the incommensurate composite crystal structure of (Ca 0.5 Y 0.5 ) 0.8 CuO 2 should be described by the combination of F2/m for the CuO 2 substructure and F2/c for the Ca 0.5 Y 0.5 substructure. The composite approach has made clear that the plane of CuO 2 chains and the sheet of (Ca, Y) atoms stack alternately to form a mutually incommensurate composite crystal with layered substructures

Two-dimensional electron gases in MgZnO/ZnO and ZnO/MgZnO/ZnO heterostructures grown by dual ion beam sputtering

Science.gov (United States)

Singh, Rohit; Arif Khan, Md; Sharma, Pankaj; Than Htay, Myo; Kranti, Abhinav; Mukherjee, Shaibal

2018-04-01

This work reports on the formation of high-density (~1013-1014 cm-2) two-dimensional electron gas (2DEG) in ZnO-based heterostructures, grown by a dual ion beam sputtering system. We probe 2DEG in bilayer MgZnO/ZnO and capped ZnO/MgZnO/ZnO heterostructures utilizing MgZnO barrier layers with varying thickness and Mg content. The effect of the ZnO cap layer thickness on the ZnO/MgZnO/ZnO heterostructure is also studied. Hall measurements demonstrate that the addition of a 5 nm ZnO cap layer results in an enhancement of the 2DEG density by about 1.5 times compared to 1.11 × 1014 cm-2 for the uncapped bilayer heterostructure with the same 30 nm barrier thickness and 30 at.% Mg composition in the barrier layer. From the low-temperature Hall measurement, the sheet carrier concentration and mobility are both found to be independent of the temperature. The capacitance-voltage measurement suggests a carrier density of ~1020 cm-3, confined in 2DEG at the MgZnO/ZnO heterointerface. The results presented are significant for the optimization of 2DEG for the eventual realization of cost-effective and large-area MgZnO/ZnO-based high-electron-mobility transistors.

A two-dimensional Zn coordination polymer with a three-dimensional supramolecular architecture

Directory of Open Access Journals (Sweden)

Fuhong Liu

2017-10-01

Full Text Available The title compound, poly[bis{μ2-4,4′-bis[(1,2,4-triazol-1-ylmethyl]biphenyl-κ2N4:N4′}bis(nitrato-κOzinc(II], [Zn(NO32(C18H16N62]n, is a two-dimensional zinc coordination polymer constructed from 4,4′-bis[(1H-1,2,4-triazol-1-ylmethyl]-1,1′-biphenyl units. It was synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. The ZnII cation is located on an inversion centre and is coordinated by two O atoms from two symmetry-related nitrate groups and four N atoms from four symmetry-related 4,4′-bis[(1H-1,2,4-triazol-1-ylmethyl]-1,1′-biphenyl ligands, forming a distorted octahedral {ZnN4O2} coordination geometry. The linear 4,4′-bis[(1H-1,2,4-triazol-1-ylmethyl]-1,1′-biphenyl ligand links two ZnII cations, generating two-dimensional layers parallel to the crystallographic (132 plane. The parallel layers are connected by C—H...O, C—H...N, C—H...π and π–π stacking interactions, resulting in a three-dimensional supramolecular architecture.

Epitaxial TiN(001) wetting layer for growth of thin single-crystal Cu(001)

Energy Technology Data Exchange (ETDEWEB)

Chawla, J. S.; Zhang, X. Y.; Gall, D. [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

2011-08-15

Single-crystal Cu(001) layers, 4-1400 nm thick, were deposited on MgO(001) with and without a 2.5-nm-thick TiN(001) buffer layer. X-ray diffraction and reflection indicate that the TiN(001) surface suppresses Cu-dewetting, yielding a 4 x lower defect density and a 9 x smaller surface roughness than if grown on MgO(001) at 25 deg. C. In situ and low temperature electron transport measurements indicate that ultra-thin (4 nm) Cu(001) remains continuous and exhibits partial specular scattering at the Cu-vacuum boundary with a Fuchs-Sondheimer specularity parameter p = 0.6 {+-} 0.2, suggesting that the use of epitaxial wetting layers is a promising approach to create low-resistivity single-crystal Cu nanoelectronic interconnects.

Electroless deposition and electrical characterization of N- Cu 2 O ...

African Journals Online (AJOL)

This work describes the preparation of n-Cu2O layer by the electroless methods of boiling and immersion of copper plates in 0.001M CuSO4Electron Microscopy (SEM) have been used to characterize the oxide films deposited. XRD studies show, for the first time, that cuprous oxide (Cu2O) and cupric oxide (CuO) were ...

Resistive switching of Cu/Cu2O junction fabricated using simple thermal oxidation at 423 K for memristor application

Science.gov (United States)

Ani, M. H.; Helmi, F.; Herman, S. H.; Noh, S.

2018-01-01

Recently, extensive researches have been done on memristor to replace current memory storage technologies. Study on active layer of memristor mostly involving n-type semiconductor oxide such as TiO2 and ZnO. This paper highlight a simple water vapour oxidation method at 423 K to form Cu/Cu2O electronic junction as a new type of memristor. Cu2O is a p-type semiconductor oxide, was used as the active layer of memristor. Cu/Cu2O/Au memristor was fabricated by thermal oxidation of copper foil, followed by sputtering of gold. Structural, morphological and memristive properties were characterized using XRD, FESEM, and current-voltage, I-V measurement respectively. Its memristivity was indentified by pinch hysteresis loop and measurement of high resistance state (HRS) and low resistance state (LRS) of the sample. The Cu/Cu2O/Au memristor demonstrates comparable performances to previous studies using other methods.

Cu2O-based solar cells using oxide semiconductors

Science.gov (United States)

Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

2016-01-01

We describe significant improvements of the photovoltaic properties that were achieved in Al-doped ZnO (AZO)/n-type oxide semiconductor/p-type Cu2O heterojunction solar cells fabricated using p-type Cu2O sheets prepared by thermally oxidizing Cu sheets. The multicomponent oxide thin film used as the n-type semiconductor layer was prepared with various chemical compositions on non-intentionally heated Cu2O sheets under various deposition conditions using a pulsed laser deposition method. In Cu2O-based heterojunction solar cells fabricated using various ternary compounds as the n-type oxide thin-film layer, the best photovoltaic performance was obtained with an n-ZnGa2O4 thin-film layer. In most of the Cu2O-based heterojunction solar cells using multicomponent oxides composed of combinations of various binary compounds, the obtained photovoltaic properties changed gradually as the chemical composition was varied. However, with the ZnO-MgO and Ga2O3-Al2O3 systems, higher conversion efficiencies (η) as well as a high open circuit voltage (Voc) were obtained by using a relatively small amount of MgO or Al2O3, e.g., (ZnO)0.91-(MgO)0.09 and (Ga2O3)0.975-(Al2O3)0.025, respectively. When Cu2O-based heterojunction solar cells were fabricated using Al2O3-Ga2O3-MgO-ZnO (AGMZO) multicomponent oxide thin films deposited with metal atomic ratios of 10, 60, 10 and 20 at.% for the Al, Ga, Mg and Zn, respectively, a high Voc of 0.98 V and an η of 4.82% were obtained. In addition, an enhanced η and an improved fill factor could be achieved in AZO/n-type multicomponent oxide/p-type Cu2O heterojunction solar cells fabricated using Na-doped Cu2O (Cu2O:Na) sheets that featured a resistivity controlled by optimizing the post-annealing temperature and duration. Consequently, an η of 6.25% and a Voc of 0.84 V were obtained in a MgF2/AZO/n-(Ga2O3-Al2O3)/p-Cu2O:Na heterojunction solar cell fabricated using a Cu2O:Na sheet with a resistivity of approximately 10 Ω·cm and a (Ga0.975Al0

Cu2O-based solar cells using oxide semiconductors

International Nuclear Information System (INIS)

Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

2016-01-01

We describe significant improvements of the photovoltaic properties that were achieved in Al-doped ZnO (AZO)/n-type oxide semiconductor/p-type Cu 2 O heterojunction solar cells fabricated using p-type Cu 2 O sheets prepared by thermally oxidizing Cu sheets. The multicomponent oxide thin film used as the n-type semiconductor layer was prepared with various chemical compositions on non-intentionally heated Cu 2 O sheets under various deposition conditions using a pulsed laser deposition method. In Cu 2 O-based heterojunction solar cells fabricated using various ternary compounds as the n-type oxide thin-film layer, the best photovoltaic performance was obtained with an n-ZnGa 2 O 4 thin-film layer. In most of the Cu 2 O-based heterojunction solar cells using multicomponent oxides composed of combinations of various binary compounds, the obtained photovoltaic properties changed gradually as the chemical composition was varied. However, with the ZnO-MgO and Ga 2 O 3 -Al 2 O 3 systems, higher conversion efficiencies (η) as well as a high open circuit voltage (V oc ) were obtained by using a relatively small amount of MgO or Al 2 O 3 , e.g., (ZnO) 0.91 –(MgO) 0.09 and (Ga 2 O 3 ) 0.975 –(Al 2 O 3 ) 0.025 , respectively. When Cu 2 O-based heterojunction solar cells were fabricated using Al 2 O 3 –Ga 2 O 3 –MgO–ZnO (AGMZO) multicomponent oxide thin films deposited with metal atomic ratios of 10, 60, 10 and 20 at.% for the Al, Ga, Mg and Zn, respectively, a high V oc of 0.98 V and an η of 4.82% were obtained. In addition, an enhanced η and an improved fill factor could be achieved in AZO/n-type multicomponent oxide/p-type Cu 2 O heterojunction solar cells fabricated using Na-doped Cu 2 O (Cu 2 O:Na) sheets that featured a resistivity controlled by optimizing the post-annealing temperature and duration. Consequently, an η of 6.25% and a V oc of 0.84 V were obtained in a MgF 2 /AZO/n-(Ga 2 O 3 –Al 2 O 3 )/p-Cu 2 O:Na heterojunction solar cell fabricated using

Ba{sub y}Sr{sub 1−y}TiO{sub 3} buffer layers for strain tuning of infinite-layer Sr{sub 1−x}La{sub x}CuO{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Sakuma, Keita, E-mail: sakuma.keita@d.mbox.nagoya-u.ac.jp; Ito, Masataka; He, Yilun; Hajiri, Tetsuya; Ueda, Kenji; Asano, Hidefumi

2016-08-01

We report on the precise tuning of lattice strain in an infinite-layer electron-doped high temperature superconductor Sr{sub 1−x}La{sub x}CuO{sub 2} (SLCO; a{sub SLCO} = 0.3949 nm for x = 0.1), which is a perovskite-related oxide, using perovskite BaTiO{sub 3}–SrTiO{sub 3} (BSTO; Ba{sub y}Sr{sub 1−y}TiO{sub 3}) buffer layers. The BSTO buffer layers formed on (001) (La{sub 0.18}Sr{sub 0.82})(Al{sub 0.59}Ta{sub 0.41})O{sub 3} substrates by magnetron sputtering were fully relaxed with high crystalline quality due to high oxygen partial pressure deposition and post annealing at 950 °C. The lattice constants of the BSTO buffer layers could be controlled in the range of 0.3926–0.3973 nm by changing the Ba content (y = 0.2–0.7). These BSTO buffer layers allow coherent growth of SLCO thin films, and a clear dependence of the superconducting transition temperature on the lattice strain was observed. The fabrication of these BSTO/superconductor heterostructures may provide novel devices composed of functional perovskite thin films, in addition to a general approach for the precise control of lattice strain in functional perovskite thin films. - Highlights: • Ba{sub y}Sr{sub 1−y}TiO{sub 3} buffer layers were developed for the strain tuning of perovskite-related oxides. • Strain effect in Sr{sub 1−x}La{sub x}CuO{sub 2} was investigated by using Ba{sub y}Sr{sub 1−y}TiO{sub 3} buffer layers. • Ba{sub y}Sr{sub 1−y}TiO{sub 3} buffer layers can be used to tune the strain in other perovskite oxides.

Superconductivity drives magnetism in δ -doped La2CuO4

Science.gov (United States)

Suter, A.; Logvenov, G.; Boris, A. V.; Baiutti, F.; Wrobel, F.; Howald, L.; Stilp, E.; Salman, Z.; Prokscha, T.; Keimer, B.

2018-04-01

Understanding the interplay between different orders in a solid is a key challenge in highly correlated electronic systems. In real systems this is even more difficult since disorder can have strong influence on the subtle balance between these orders and thus can obscure the interpretation of the observed physical properties. Here we present a study on δ -doped La2CuO4 (δ -LCON ) superlattices. By means of molecular beam epitaxy whole LaO2 layers were periodically replaced by SrO2 layers, providing a charge reservoir yet reducing the level of disorder typically present in doped cuprates to an absolute minimum. The induced superconductivity and its interplay with the antiferromagnetic order is studied by means of low-energy muon spin rotation. We find a quasi-two-dimensional superconducting state which couples to the antiferromagnetic order in a nontrivial way. Below the superconducting transition temperature, the magnetic volume fraction increases strongly. The reason could be a charge redistribution of the free carriers due to the opening of the superconducting gap which is possible due to the close proximity and low disorder between the different ordered regions.

Static and dynamic magnetic properties of two synthetic francisites Cu3La(SeO3)2O2X (X = Br and Cl)

Science.gov (United States)

Markina, M. M.; Zakharov, K. V.; Zvereva, E. A.; Denisov, R. S.; Berdonosov, P. S.; Dolgikh, V. A.; Kuznetsova, E. S.; Olenev, A. V.; Vasiliev, A. N.

2017-04-01

The formation of long-range magnetic order at low temperatures was established in francisite—type compounds Cu3La(SeO3)2O2X (X = Br and Cl) through measurements of magnetic susceptibility, magnetization, specific heat and X-band electron spin resonance. The significantly enhanced critical index p = 1.0 ± 0.1 in Cu3La(SeO3)2Br and p = 0.8 ± 0.1 in Cu3La(SeO3)2Cl in the temperature dependence of the width of ESR signal evidence the reduced dimensionality of the kagome-type francisite's magnetic subsystem. Under action of external magnetic field, the presumably non-collinear six-sublattices antiferromagnetic structure of these compounds experiences the first-order metamagnetic transformation. The B- T magnetic phase diagrams were established from the positions of singularities in temperature and field dependences of thermodynamic properties. Contrary to pristine mineral Cu3Bi(SeO3)2Cl, no signature of structural phase transition was detected.

Atomic layer deposition of HfO{sub 2} for integration into three-dimensional metal-insulator-metal devices

Energy Technology Data Exchange (ETDEWEB)

Assaud, Loic [Aix Marseille Univ, CNRS, CINAM, Marseille (France); ICMMO-ERIEE, Universite Paris-Sud / Universite Paris-Saclay, CNRS, Orsay (France); Pitzschel, Kristina; Barr, Maissa K.S.; Petit, Matthieu; Hanbuecken, Margrit; Santinacci, Lionel [Aix Marseille Univ, CNRS, CINAM, Marseille (France); Monier, Guillaume [Universite Clermont Auvergne, Universite Blaise Pascal, CNRS, Institut Pascal, Clermont-Ferrand (France)

2017-12-15

HfO{sub 2} nanotubes have been fabricated via a template-assisted deposition process for further use in three-dimensional metal-insulator-metal (MIM) devices. HfO{sub 2} thin layers were grown by Atomic Layer Deposition (ALD) in anodic alumina membranes (AAM). The ALD was carried out using tetrakis(ethylmethylamino)hafnium and water as Hf and O sources, respectively. Long exposure durations to the precursors have been used to maximize the penetration depth of the HfO{sub 2} layer within the AAM and the effect of the process temperature was investigated. The morphology, the chemical composition, and the crystal structure were studied as a function of the deposition parameters using transmission and scanning electron microscopies, X-ray photoelectron spectroscopy, and X-ray diffraction, respectively. As expected, the HfO{sub 2} layers grown at low-temperature (T = 150 C) were amorphous, while for a higher temperature (T = 250 C), polycrystalline films were observed. The electrical characterizations have shown better insulating properties for the layers grown at low temperature. Finally, TiN/HfO{sub 2}/TiN multilayers were grown in an AAM as proof-of-concept for three-dimensional MIM nanostructures. (orig.)

Improvement of in-plane alignment for surface oxidized NiO layer on textured Ni substrate by two-step heat-treatment

International Nuclear Information System (INIS)

Hasegawa, Katsuya; Izumi, Toru; Izumi, Teruo; Shiohara, Yuh; Maeda, Toshihiko

2004-01-01

Epitaxial growth of NiO on a textured Ni substrate as a template for an REBa 2 Cu 3 O y coated conductor was investigated. Highly in-plane aligned NiO layers were successfully fabricated using a new process of a two-step heat-treatment for oxidation. In the first-step, a highly in-plane aligned thin NiO layer was formed on a textured Ni substrate under a low driving force of oxidation. Then, in the second-step, a thick NiO layer was grown at a higher rate with maintaining its high in-plane grain alignment, as if the first NiO layer acts as a seed crystal layer. Further, growth rates and microstructures of the NiO layers were studied comparatively in the cases with and without the first layer. It was found that the oxidation rate in the case with the first layer was lower than that without the first layer. The microstructure observation revealed that the NiO without the first layer was poly-crystalline with many grain-boundaries. On the other hand, in the case with the first layer, grain-boundaries of the NiO were hardly observed. Hence, the reason for this difference of the growth rate and the microstructure of the NiO layers were discussed in view of a diffusivity path

3D coordination polymers with nitrilotriacetic and 4,4'-bipyridyl mixed ligands: structural variation based on dinuclear or tetranuclear subunits assisted by Na-O and/or O-H...O interactions.

Science.gov (United States)

Lü, Xing-Qiang; Jiang, Ji-Jun; Chen, Chun-Long; Kang, Bei-Sheng; Su, Cheng-Yong

2005-06-27

The reactions of Cu(II) with the mixed nitrilotriacetic acid (H3NTA) and 4,4'-bipyridyl (4,4'-bpy) ligands in different metal-to-ligand ratios in the presence of NaOH and NaClO4 afforded two complexes, Na3[Cu2(NTA)2(4,4'-bpy)]ClO4 x 5H2O (1) and [Cu2(NTA) (4,4'-bpy)2]ClO4 x 4H2O (2). The two complexes have been characterized by elemental analysis, IR, XRD, and single-crystal X-ray diffraction. 1 contains a basic doubly negatively charged [Cu2(NTA)2(4,4'-bpy)]2- dinuclear unit which was further assembled via multiple Na-O and O-H...O interactions into a three-dimensional (3D) pillared-layer structure. 2 features a two-dimensional (2D) undulated brick-wall architecture containing a basic doubly positively charged [Cu4(NTA)2(4,4'-bpy)2]2+ tetranuclear unit. The 2D network possesses large cavities hosting guest molecules and was further assembled via O-H...O hydrogen bonds into a 3D structure with several channels running in different directions.

La{sub 3}Cu{sub 4}P{sub 4}O{sub 2} and La{sub 5}Cu{sub 4}P{sub 4}O{sub 4}Cl{sub 2}. Synthesis, structure and {sup 31}P solid state NMR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Bartsch, Timo; Eul, Matthias; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Benndorf, Christopher; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. of Physics

2016-04-01

The phosphide oxides La{sub 3}Cu{sub 4}P{sub 4}O{sub 2} and La{sub 5}Cu{sub 4}P{sub 4}O{sub 4}Cl{sub 2} were synthesized from lanthanum, copper(I) oxide, red phosphorus, and lanthanum(III) chloride through a ceramic technique. Single crystals can be grown in a NaCl/KCl flux. Both structures were refined from single crystal X-ray diffractometer data: I4/mmm, a = 403.89(4), c = 2681.7(3) pm, wR2 = 0.0660, 269 F{sup 2} values, 19 variables for La{sub 3}Cu{sub 4}P{sub 4}O{sub 2} and a = 407.52(5), c = 4056.8(7) pm, wR2 = 0.0905, 426 F{sup 2} values, 27 variables for La{sub 5}Cu{sub 4}P{sub 4}O{sub 4}Cl{sub 2}. Refinement of the occupancy parameters revealed full occupancy for the oxygen sites in both compounds. The structures are composed of cationic (La{sub 2}O{sub 2}){sup 2+} layers and covalently bonded (Cu{sub 4}P{sub 4}){sup 5-} polyanionic layers with metallic characteristics, and an additional La{sup 3+} between two adjacent (Cu{sub 4}P{sub 4}){sup 5-} layers. The structure of La{sub 5}Cu{sub 4}P{sub 4}O{sub 4}Cl{sub 2} comprises two additional LaOCl slabs per unit cell. Temperature-dependent magnetic susceptibility studies revealed Pauli paramagnetism. The phosphide substructure of La{sub 3}Cu{sub 4}P{sub 4}O{sub 2} was studied by {sup 31}P solid state NMR spectroscopy. By using a suitable dipolar re-coupling approach the two distinct resonances belonging to the P{sub 2}{sup 4-} and the P{sup 3-} units could be identified.

Temperature-dependent layer breathing modes in two-dimensional materials

Science.gov (United States)

Maity, Indrajit; Maiti, Prabal K.; Jain, Manish

2018-04-01

Relative out-of-plane displacements of the constituent layers of two-dimensional materials give rise to unique low-frequency breathing modes. By computing the height-height correlation functions from molecular dynamics simulations, we show that the layer breathing modes (LBMs) can be mapped consistently to vibrations of a simple linear chain model. Our calculated thickness dependence of LBM frequencies for few-layer (FL) graphene and molybdenum disulfide (MoS2) are in excellent agreement with available experiments. Our results show a redshift of LBM frequency with an increase in temperature, which is a direct consequence of anharmonicities present in the interlayer interaction. We also predict the thickness and temperature dependence of LBM frequencies for FL hexagonal boron nitride. Our Rapid Communication provides a simple and efficient way to probe the interlayer interaction for layered materials and their heterostructures with the inclusion of anharmonic effects.

A Novel Ternary CoFe2O4/CuO/CoFe2O4 as a Giant Magnetoresistance Sensor

Directory of Open Access Journals (Sweden)

Ramli

2016-12-01

Full Text Available This paper reports the results of a study relating to the synthesis of a novel ternary CoFe2O4/CuO/CoFe2O4 thin film as a giant magnetoresistance (GMR sensor. The CoFe2O4/CuO/CoFe2O4 thin film was prepared onto silicon substrate via DC magnetron sputtering with the targets facing each other. X-ray diffraction was used to determine the structure of the thin film and a 4-point method was used to measure the MR ratio. The GMR ratio is highly dependent on the ferrimagnetic (CoFe2O4 and nonmagnetic (CuO layer thickness. The maximum GMR ratio at room temperature obtained in the CoFe2O4/CuO/CoFe2O4 thin film was 70% when the CoFe2O4 and the CuO layer had a thickness of 62.5 nm and 14.4 nm respectively.

Spectroscopic Studies of a Three-dimensional, Five-coordinated Copper(Ⅱ) Complex via Hydrogen Bonds: [Cu(PDA)(H2O)2](H2PDA=Pyridine-2,6-dicarboxylic Acid)

Institute of Scientific and Technical Information of China (English)

无

2003-01-01

A new copper(Ⅱ) complex [Cu(PDA)(H2O)2] was synthesized and its structure was determined. Cu(Ⅱ) is five-coordinated in a tetragonal pyramid geometry. The two coordinating water molecules are different and the two Cu-O bond lengths differ by nearly 0.02 nm. The whole crystal is linked to form a three-dimensional network by means of hydrogen bonds. The X-band ESR spectrum shows three different g tensors with a well-resolved hyperfine structure in the gz signal, giving the ESR parameters gx=2.05, gy=2.065 and gz=2.29. The covalency of the coordinate bonds and the deviation from tetragonal pyramid geometry for the complex are discussed based on the ESR spectra.

Magnetism of CuCl{sub 2}·2D{sub 2}O and CuCl{sub 2}·2H{sub 2}O, and of CuBr{sub 2}·6H{sub 2}O

Energy Technology Data Exchange (ETDEWEB)

DeFotis, G.C., E-mail: gxdefo@wm.edu [Department of Chemistry, College of William and Mary, Williamsburg, VA 23187 (United States); Hampton, A.S.; Van Dongen, M.J.; Komatsu, C.H.; Benday, N.S.; Davis, C.M. [Department of Chemistry, College of William and Mary, Williamsburg, VA 23187 (United States); Hays, K.; Wagner, M.J. [Department of Chemistry, George Washington University, Washington, D.C. 20052 (United States)

2017-07-15

Highlights: • CuCl{sub 2}·2D{sub 2}O is examined magnetically and compared with CuCl{sub 2}·2H{sub 2}O. • Slightly lower magnetic characteristic temperatures occur for deuterated dihydrate. • The new compound CuBr{sub 2}·6H{sub 2}O is examined magnetically. • Unexpected relationships appears between magnetic behaviors of CuBr{sub 2}·6H{sub 2}O and CuBr{sub 2}. • Two alternative monoclinic unit cells can account for diffraction data on CuBr{sub 2}·6H{sub 2}O. - Abstract: The magnetic properties of little examined CuCl{sub 2}·2D{sub 2}O are studied and compared with those of CuCl{sub 2}·2H{sub 2}O. New CuBr{sub 2}·6H{sub 2}O is also examined. Susceptibility maxima appear for chlorides at 5.35 and 5.50 K, in the above order, with estimated antiferromagnetic ordering at 4.15 and 4.25 K. Curie-Weiss fits yield g of 2.210 and 2.205, and Weiss θ of −6.0 and −4.7 K, respectively, in χ{sub M} = C/(T − θ). One-dimensional Heisenberg model fits to susceptibilities, including interchain exchange in a mean-field approximation, are performed. Interchain exchange is significant but much weaker than intrachain. The bromide hexahydrate strongly differs magnetically from any chloride hydrate, but exhibits notable similarities and differences compared to previously studied CuBr{sub 2}. A broad susceptibility maximum occurs near 218 K, only 4% lower than for CuBr{sub 2}, but with almost twice the magnitude. Powder X-ray diffraction data for CuBr{sub 2}·6H{sub 2}O may be best accounted for by a monoclinic unit cell that is metrically orthorhombic. The volume per formula unit is consistent with trends in metal ionic radii. However, an alternative monoclinic cell with 5% smaller volume more readily rationalizes the magnetism.

On-stack two-dimensional conversion of MoS2 into MoO3

Science.gov (United States)

Yeoung Ko, Taeg; Jeong, Areum; Kim, Wontaek; Lee, Jinhwan; Kim, Youngchan; Lee, Jung Eun; Ryu, Gyeong Hee; Park, Kwanghee; Kim, Dogyeong; Lee, Zonghoon; Lee, Min Hyung; Lee, Changgu; Ryu, Sunmin

2017-03-01

Chemical transformation of existing two-dimensional (2D) materials can be crucial in further expanding the 2D crystal palette required to realize various functional heterostructures. In this work, we demonstrate a 2D ‘on-stack’ chemical conversion of single-layer crystalline MoS2 into MoO3 with a precise layer control that enables truly 2D MoO3 and MoO3/MoS2 heterostructures. To minimize perturbation of the 2D morphology, a nonthermal oxidation using O2 plasma was employed. The early stage of the reaction was characterized by a defect-induced Raman peak, drastic quenching of photoluminescence (PL) signals and sub-nm protrusions in atomic force microscopy images. As the reaction proceeded from the uppermost layer to the buried layers, PL and optical second harmonic generation signals showed characteristic modulations revealing a layer-by-layer conversion. The plasma-generated 2D oxides, confirmed as MoO3 by x-ray photoelectron spectroscopy, were found to be amorphous but extremely flat with a surface roughness of 0.18 nm, comparable to that of 1L MoS2. The rate of oxidation quantified by Raman spectroscopy decreased very rapidly for buried sulfide layers due to protection by the surface 2D oxides, exhibiting a pseudo-self-limiting behavior. As exemplified in this work, various on-stack chemical transformations can be applied to other 2D materials in forming otherwise unobtainable materials and complex heterostructures, thus expanding the palette of 2D material building blocks.

Current transport and electronic states in a,b-axis-oriented YBa2Cu3O7/PrBa2Cu3O7/YBa2Cu3O7 sandwich-type junctions

International Nuclear Information System (INIS)

Yoshida, J.; Nagano, T.; Hashimoto, T.

1996-01-01

Precise measurement of the temperature and voltage dependence of junction conductance has been carried out for a,b-axis-oriented YBa 2 Cu 3 O 7 /PrBa 2 Cu 3 O 7 /YBa 2 Cu 3 O 7 sandwich-type junctions to investigate the possible origin of Josephson coupling in these junctions. Regardless of the presence or absence of the Josephson effect, most of the junctions exhibited a dip in conductance around zero voltage in their dI/dV profiles at low temperatures. This dI/dV anomaly was attributed to the existence of a minimum in the density of states due to electron-electron interaction in disordered metals in the vicinity of a tunneling barrier within the junctions. The complex temperature dependence of junction conductance was reproduced well by a theoretical model in which both tunneling conduction paths and variable range hopping paths were assumed to exist within the PrBa 2 Cu 3 O 7 barrier layer. No definite evidence of current transport through a small number of localized levels or a metallic conduction path in PrBa 2 Cu 3 O 7 has been confirmed, even for junctions with a 20-nm-thick barrier layer. copyright 1996 The American Physical Society

Two-Dimensional SnO Anodes with a Tunable Number of Atomic Layers for Sodium Ion Batteries

KAUST Repository

Zhang, Fan

2017-01-18

We have systematically changed the number of atomic layers stacked in 2D SnO nanosheet anodes and studied their sodium ion battery (SIB) performance. The results indicate that as the number of atomic SnO layers in a sheet decreases, both the capacity and cycling stability of the Na ion battery improve. The thinnest SnO nanosheet anodes (two to six SnO monolayers) exhibited the best performance. Specifically, an initial discharge and charge capacity of 1072 and 848 mAh g-1 were observed, respectively, at 0.1 A g-1. In addition, an impressive reversible capacity of 665 mAh g-1 after 100 cycles at 0.1 A g-1 and 452 mAh g-1 after 1000 cycles at a high current density of 1.0 A g-1 was observed, with excellent rate performance. As the average number of atomic layers in the anode sheets increased, the battery performance degraded significantly. For example, for the anode sheets with 10-20 atomic layers, only a reversible capacity of 389 mAh g-1 could be obtained after 100 cycles at 0.1 A g-1. Density functional theory calculations coupled with experimental results were used to elucidate the sodiation mechanism of the SnO nanosheets. This systematic study of monolayer-dependent physical and electrochemical properties of 2D anodes shows a promising pathway to engineering and mitigating volume changes in 2D anode materials for sodium ion batteries. It also demonstrates that ultrathin SnO nanosheets are promising SIB anode materials with high specific capacity, stable cyclability, and excellent rate performance.

Stabilizing and Organizing Bi3 Cu4 and Bi7 Cu12 Nanoclusters in Two-Dimensional Metal-Organic Networks.

Science.gov (United States)

Yan, Linghao; Xia, Bowen; Zhang, Qiushi; Kuang, Guowen; Xu, Hu; Liu, Jun; Liu, Pei Nian; Lin, Nian

2018-04-16

Multinuclear heterometallic nanoclusters with controllable stoichiometry and structure are anticipated to possess promising catalytic, magnetic, and optical properties. Heterometallic nanoclusters with precise stoichiometry of Bi 3 Cu 4 and Bi 7 Cu 12 can be stabilized in the scaffold of two-dimensional metal-organic networks on a Cu(111) surface through on-surface metallosupramolecular self-assembly processes. The atomic structures of the nanoclusters were resolved using scanning tunneling microscopy and density functional theory calculations. The nanoclusters feature highly symmetric planar hexagonal shapes and core-shell charge modulation. The clusters are arranged as triangular lattices with a periodicity that can be tuned by choosing molecules of different size. This work shows that on-surface metallosupramolecular self-assembly creates unique possibilities for the design and synthesis of multinuclear heterometallic nanoclusters. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrogen-bonded Three-Dimensional Networks Encapsulating One-dimensional Covalent Chains: [Cu(3-ampy)(H2O)4](SO4)·(H2O) (3-ampy = 3-Aminopyridine)

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

A three-dimensional complex [Cu(3-ampy)(H2O)4](SO4)·(H2O) (3-ampy = 3-aminopyridine) has been synthesized. Crystallographic data: C5H16CuN2O9S, Mr = 343.80, triclinic, space group P, a = 7.675(2), b = 8.225(3), c = 10.845(3) (A), α= 86.996(4), β = 76.292(4),γ = 68.890(4)°, V = 620.0(3) (A)3, Z = 2, Dc = 1.841 g/cm3, F(000) = 354 and μ = 1.971 mm-1. The structure was refined to R = 0.0269 and wR = 0.0659 for 1838 observed reflections (I ＞ 2σ(Ⅰ)). The structure consists of [Cu(3-ampy)(H2O)4]2+ cations, SO42- anions and lattice water molecules. 3-Ampy acting as a bidentate bridging ligand generates a 1D covalent chain. A supramolecular 2D framework is formed through π-π stacking of pyridine rings. The lattice water molecules and SO42- anions are located between the adjacent 2D frameworks. The hydrogen bonding interactions from lattice water molecules and SO42- anions to coordinate water extend the 2D framework into a 3D network.

Copper(II) perrhenate Cu(C{sub 3}H{sub 7}OH){sub 2}(ReO{sub 4}){sub 2}: Synthesis from isopropanol and CuReO{sub 4}, structure and properties

Energy Technology Data Exchange (ETDEWEB)

Mikhailova, D., E-mail: d.mikhailova@ifw-dresden.de [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM), Hermann-von-Helmholtz-Platz 1, D-76434 Eggenstein-Leopoldshafen (Germany); Institute for Complex Materials, IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden (Germany); Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, D-01187 Dresden (Germany); Engel, J.M. [Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 2, D-64287 Darmstadt (Germany); Schmidt, M. [Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, D-01187 Dresden (Germany); Tsirlin, A.A. [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Ehrenberg, H. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM), Hermann-von-Helmholtz-Platz 1, D-76434 Eggenstein-Leopoldshafen (Germany); Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 2, D-64287 Darmstadt (Germany)

2015-12-15

The crystal structure of Cu{sup +}Re{sup 7+}O{sub 4} is capable of a quasi-reversible incorporation of C{sub 3}H{sub 7}OH molecules. A room-temperature reaction between CuReO{sub 4} and C{sub 3}H{sub 7}OH under oxidizing conditions leads to the formation of a novel metal-organic hybrid compound Cu{sup 2+}(C{sub 3}H{sub 7}OH){sub 2}(ReO{sub 4}){sub 2}. Upon heating under reducing conditions, this compound transforms back into CuReO{sub 4}, albeit with ReO{sub 2} and metallic Cu as by-products. The crystal structure of Cu(C{sub 3}H{sub 7}OH){sub 2}(ReO{sub 4}){sub 2} solved from single-crystal X-ray diffraction (Pbca, a=10.005(3) Å, b=7.833(2) Å, and c=19.180(5) Å) reveals layers of corner-sharing CuO{sub 6}-octahedra and ReO{sub 4}-tetrahedra, whereas isopropyl groups are attached to both sides of these layers, thus providing additional connections within the layers through hydrogen bonds. Cu(C{sub 3}H{sub 7}OH){sub 2}(ReO{sub 4}){sub 2} is paramagnetic down to 4 K because the spatial arrangement of the Cu{sup 2+} half-filled orbitals prevents magnetic superexchange. The paramagnetic effective moment of 2.0(1) μ{sub B} is slightly above the spin-only value and typical for Cu{sup 2+} ions. - Highlights: • Novel Cu(C{sub 3}H{sub 7}OH){sub 2}(ReO{sub 4}){sub 2} compound has a sequence of inorganic and organic layers. • Hydrogen bonds provide an additional bonding Isopropanol molecules serve as a reducing agent during decomposition. • No direct Cu-O-Re-O-Cu connections via d{sub x2-y2} orbital of Cu{sup 2+} explain paramagnetism. • Hydrogen bonds provide an additional bonding. • Isopropanol molecules serve as a reducing agent during decomposition.

Device and performance parameters of Cu(In,Ga)(Se,S)2-based solar cells with varying i-ZnO layer thickness

International Nuclear Information System (INIS)

Macabebe, E.Q.B.; Sheppard, C.J.; Dyk, E.E. van

2009-01-01

In pursuit of low-cost and highly efficient thin film solar cells, Cu(In,Ga)(Se,S) 2 /CdS/i-ZnO/ZnO:Al (CIGSS) solar cells were fabricated using a two-step process. The thickness of i-ZnO layer was varied from 0 to 454 nm. The current density-voltage (J-V) characteristics of the devices were measured, and the device and performance parameters of the solar cells were obtained from the J-V curves to analyze the effect of varying i-ZnO layer thickness. The device parameters were determined using a parameter extraction method that utilized particle swarm optimization. The method is a curve-fitting routine that employed the two-diode model. The J-V curves of the solar cells were fitted with the model and the parameters were determined. Results show that as the thickness of i-ZnO was increased, the average efficiency and the fill factor (FF) of the solar cells increase. Device parameters reveal that although the series resistance increased with thicker i-ZnO layer, the solar cells absorbed more photons resulting in higher short-circuit current density (J sc ) and, consequently, higher photo-generated current density (J L ). For solar cells with 303-454 nm-thick i-ZnO layer, the best devices achieved efficiency between 15.24% and 15.73% and the fill factor varied between 0.65 and 0.67.

ZnO/Cu/ZnO multilayer films: Structure optimization and investigation on photoelectric properties

International Nuclear Information System (INIS)

Liu Xiaoyu; Li Yingai; Liu Shi; Wu Honglin; Cui Haining

2012-01-01

A series of ZnO/Cu/ZnO multilayer films has been fabricated from zinc and copper metallic targets by simultaneous RF and DC magnetron sputtering. Numerical simulation of the optical properties of the multilayer films has been carried out in order to guide the experimental work. The influences of the ZnO and Cu layer thicknesses, and of O 2 /Ar ratio on the photoelectric and structural properties of the films were investigated. The optical and electrical properties of the multilayers were studied by optical spectrometry and four point probe measurements, respectively. The structural properties were investigated using X-ray diffraction. The performance of the multilayers as transparent conducting coatings was compared using a figure of merit. In experiments, the thickness of the ZnO layers was varied between 4 and 70 nm and those of Cu were between 8 and 37 nm. The O 2 /Ar ratios range from 1:5 to 2:1. Low sheet resistance and high transmittance were obtained when the film was prepared using an O 2 /Ar ratio of 1:4 and a thickness of ZnO (60 nm)/Cu (15 nm)/ZnO (60 nm). - Highlights: ► ZnO/Cu/ZnO films were fabricated from zinc and copper targets by sputtering. ► Transmittance reaches maximum when top and bottom ZnO thicknesses are nearly equal. ► Sheet resistance increases with increasing ZnO layer thickness. ► Variation in sheet resistance with oxygen/argon ratio is due to interface effect.

Controllable synthesis and enhanced photocatalytic properties of Cu2O/Cu31S16 composites

International Nuclear Information System (INIS)

Liu, Xueqin; Li, Zhen; Zhang, Qiang; Li, Fei

2012-01-01

Highlights: ► Facile sonochemical route. ► The content of Cu 31 S 16 in the Cu 2 O/Cu 31 S 16 can be easily controlled. ► Structure and optical properties of Cu 2 O/Cu 31 S 16 were discussed. ► Enhanced photocatalytic property of Cu 2 O/Cu 31 S 16 . ► Cu 2 O/Cu 31 S 16 core/shell structures were more stable than single Cu 2 O particles. -- Abstract: The controlled synthesis of Cu 2 O/Cu 31 S 16 microcomposites with hierarchical structures had been prepared via a convenient sonochemical route. Ultrasonic irradiation of a mixture of Cu 2 O and (NH 2 ) 2 CS in an aqueous medium yielded Cu 2 O/Cu 31 S 16 composites. The content of Cu 31 S 16 in the Cu 2 O/Cu 31 S 16 can be easily controlled by adjusting the synthesis time. The Cu 31 S 16 layer not only protected and stabilized Cu 2 O particles, but also prohibited the recombination of photogenerated electrons–holes pair between Cu 31 S 16 and Cu 2 O. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) spectra, ultraviolet–visible (UV–Vis) spectroscopy and photoluminescence (PL) spectroscopy were used to characterize the products. Photocatalytic performance of the Cu 2 O/Cu 31 S 16 hierarchical structures was evaluated by measuring the decomposition rate of methyl orange solution under natural light. To the best of our knowledge, this is the first report on the preparation and photocatalytic activity of Cu 2 O/Cu 31 S 16 microcomposite. Additionally, the Cu 2 O/Cu 31 S 16 core/shell structures were more stable than single Cu 2 O particles during photocatalytic process since the photocatalytic activity of the second reused architecture sample was much higher than that of pure Cu 2 O. The Cu 2 O/Cu 31 S 16 microcomposites may be a good promising candidate for wastewater treatment.

Positron lifetime studies on the BiSrCaCuO(F) superconductors

International Nuclear Information System (INIS)

Shi Zhiqiang; Chao Xixu; Wu Lingyun

1995-01-01

We have measured the positron lifetime and the transition temperature T c as a function of doped F content for Bi 2 Sr 2 CaCu 2 O y-x F x superconductors. The observed results are interpreted in terms of the change of the electron density in the Bi - O layers, which is the region probed by the positron, and the hole concentration in the Cu - O planes, which is correlated with the T c of the sample. From this point of view, it is suggested that the F atom mainly substitutes the oxygen atom in the Bi - O layers, and it causes the electrons transfer from the Bi - O layers to the Sr - O planes; when x = 0.4, the F atom mainly substitues the oxygen atom in the Sr - O planes, it causes the electrons transfer from the Sr - O planes to the Bi - O layers and the Cu - O planes. (orig.)

Defect formation and carrier doping in epitaxial films of the ''parent'' compound SrCuO2: Synthesis of two superconductors descendants

International Nuclear Information System (INIS)

Feenstra, R.; Norton, D.P.; Budai, J.D.; Jones, E.C.; Christen, D.K.; Kawai, T.

1995-04-01

The infinite layer or parent compounds ACuO 2 (A: Ca-Sr-Ba) constitute the simplest copper oxygen perovskites that contain the CuO 2 sheets essential for superconductivity. The stabilization of these basic ''building blocks'' as epitaxial films, therefore, provides alluring opportunities towards the search for new superconducting compounds and elucidation of the underlying mechanisms. In this work, general trends of the defect formation and carrier doping for epitaxial films of the intermediate endmember SrCuO 2 are reviewed. First results are presented from successful attempts to induce hole-doped superconductivity via the processing-controlled incorporation of charge reservoir layers

New magnetic materials obtained by ion-exchange reactions from non-magnetic layered perovskites

International Nuclear Information System (INIS)

Kageyama, H; Viciu, L; Caruntu, G; Ueda, Y; Wiley, J B

2004-01-01

New layered magnetic materials (MCl)Ca 2 Ta 3 O 10 (M = Cu, Fe), have been prepared by ion-exchange reactions of non-magnetic perovskite derivatives, ACa 2 Ta 3 O 10 (A = Rb, Li), in corresponding anhydrous molten salts. Powder x-ray diffraction patterns of the products are successfully indexed assuming tetragonal symmetry with cell dimensions a = 3.829 A and c = 15.533 A for Cu, and a = 3.822 A and c = 15.672 A for Fe. Being separated by the Ca 2 Ta 3 O 10 triple-layer perovskite slabs, the transition-metal chloride (MCl) network provides a two-dimensional magnetic lattice. Magnetic susceptibility measurements show that (CuCl)Ca 2 Ta 3 O 10 is in an antiferromagnetic state below 8 K, while (FeCl)Ca 2 Ta 3 O 10 has two anomalies at 91 and 125 K, suggesting successive phase transitions due to geometrical spin frustration

catena-Poly[[aquabis[N-(pyridin-3-ylisonicotinamide-κN1]copper(II]-μ-fumarato-κ2O1:O4

Directory of Open Access Journals (Sweden)

Sultan H. Qiblawi

2012-12-01

Full Text Available In the title compound, [Cu(C4H2O4(C11H9N3O2(H2O]n, CuII ions on crystallographic twofold rotation axes are coordinated in a square pyramidal environment by two trans O atoms belonging to two monodentate fumarate anions, two trans isonicotinamide pyridyl N-donor atoms from monodentate, pendant 3-pyridylisonicotinamide (3-pina ligands, and one apical aqua ligand, also sited on the crystallographic twofold rotation axis. The exobidentate fumarate ligands form [Cu(fumarate(3-pina2(H2O]n coordination polymer chains that are arranged parallel to [001]. In the crystal, these polymeric chains are anchored into supramolecular layers parallel to (100 by O—H...O hydrogen bonds between aqua ligands and unligating fumarate O atoms, and N—H...O(=C hydrogen bonds between 3-pina ligands. In turn, the layers aggregate by weak C—H...N and C—H...O hydrogen bonds, affording a three-dimensional network.

Melt processing of Bi-Ca-Sr-Cu-O superconductors

International Nuclear Information System (INIS)

Zanotto, E.D.; Cronin, J.P.; Dutta, B.

1988-01-01

Several Bi-Ca-Sr-Cu-O compositions were melted in Al/sub 2/O/sub 3/ or Pt crucibles at temperatures between 1050C and 1200C. As-quenched specimens crystallized from the upper surfaces, while the bottom layers were glassy. Glass formation was improved for higher Bi/sub 2/O/sub 3/ concentrations. The crystalline portions were highly conductive, while the glassy layers were insulating. Both did not show superconductivity down to 10K. Thermal treatment in air caused a dramatic effect on the electronic properties; and annealing at 865C for long periods converted the two types of specimens (previously glassy or crystalline) to superconductors, at least for one composition. Aluminum impurity (up to 8.6 atom. pct.) had no detectable effect on the transition temperatures, i.e., T/sub c/ 85K for all superconducting samples. The flake-like (Bi/sub 2/Ca/sub 1/Sr/sub 2/Cu/sub 2/) phase, reported by other authors, was responsible for superconductivity

Hole distribution in (Sr, Ca, Y, La)14Cu24O41 compounds studies by x-ray absorption and emission spectroscopy

International Nuclear Information System (INIS)

Kabasawa, Eiki; Nakamura, Jin; Yamada, Nobuyoshi; Kuroki, Kazuhiko; Yamazaki, Hisashi; Watanabe, Masamitsu; Denlinger, Jonathan D.; Shin, Shik; Perera, Rupert C.C.

2008-01-01

The polarization dependence of soft x-ray absorption spectroscopy (XAS) and x-ray emission spectroscopy (XES) near the O 1s 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. (author)

CuO-Functionalized Silicon Photoanodes for Photoelectrochemical Water Splitting Devices.

Science.gov (United States)

Shi, Yuanyuan; Gimbert-Suriñach, Carolina; Han, Tingting; Berardi, Serena; Lanza, Mario; Llobet, Antoni

2016-01-13

One main difficulty for the technological development of photoelectrochemical (PEC) water splitting (WS) devices is the fabrication of active, stable and cost-effective photoelectrodes that ensure high performance. Here, we report the development of a CuO/Silicon based photoanode, which shows an onset potential for the water oxidation of 0.53 V vs SCE at pH 9, that is, an overpotential of 75 mV, and high stability above 10 h. These values account for a photovoltage of 420 mV due to the absorbed photons by silicon, as proven by comparing with analogous CuO/FTO electrodes that are not photoactive. The photoanodes have been fabricated by sputtering a thin film of Cu(0) on commercially available n-type Si wafers, followed by a photoelectrochemical treatment in basic pH conditions. The resulting CuO/Cu layer acts as (1) protective layer to avoid the corrosion of nSi, (2) p-type hole conducting layer for efficient charge separation and transportation, and (3) electrocatalyst to reduce the overpotential of the water oxidation reaction. The low cost, low toxicity, and good performance of CuO-based coatings can be an attractive solution to functionalize unstable materials for solar energy conversion.

Polarity driven morphology of CeO{sub 2}(1 0 0) islands on Cu(1 1 1)

Energy Technology Data Exchange (ETDEWEB)

Stetsovych, O., E-mail: stetsovycholeksandr@gmail.com; Beran, J.; Dvořák, F.; Mašek, K.; Mysliveček, J., E-mail: Josef.Myslivecek@mff.cuni.cz; Matolín, V.

2013-11-15

Thin ceria films supported by metal substrates represent important model systems for reactivity studies in heterogeneous catalysis. Here we report the growth study of the polar CeO{sub 2}(1 0 0) phase as part of a mixed CeO{sub 2}(1 1 1)–CeO{sub 2}(1 0 0) thin film supported by Cu(1 1 1). The two ceria phases grow on different areas of the substrate, what allows a reliable growth characterization of the CeO{sub 2}(1 0 0) islands on Cu(1 1 1). Scanning tunneling microscopy measurements reveal CeO{sub 2}(1 0 0) to grow in the form of highly dispersed three dimensional (3D) islands on a CeO{sub 2}(1 0 0) interfacial layer. The CeO{sub 2}(1 0 0) islands exhibit a 2 × 2 surface reconstruction. The presence of the surface reconstruction together with the highly dispersed growth of CeO{sub 2}(1 0 0) islands corresponds to the requirement for compensation of the surface dipole moment on the CeO{sub 2}(1 0 0). CeO{sub 2}(1 0 0) islands are further characterized by reflection high energy electron diffraction yielding their epitaxial relations with respect to the Cu(1 1 1) substrate. The growth of well characterized CeO{sub 2}(1 0 0) islands supported by Cu(1 1 1) represents a starting point for developing a novel template for structure-related reactivity studies of ceria based model catalysts.

Critical current density of strained multilayer thin films of Nd1.83Ce0.17CuOx/YBa2Cu3O7-δ

International Nuclear Information System (INIS)

Gross, R.; Gupta, A.; Olsson, E.; Segmueller, A.; Koren, G.

1990-01-01

The superconducting transport properties of strained multilayer thin films of YBa 2 Cu 3 O 7-δ / Nd 1.83 Ce 0.17 CuO x , grown heteroepitaxially by laser ablation deposition, are reported. For individual layer thicknesses below a critical layer thickness of about 250 A, coherency strain removes the orthorhombic distortion in the YBa 2 Cu 3 O 7-δ layers and makes them twin-free. Zero-field critical current densities as high as 1.1x10 7 A/cm 2 at 77 K have been measured for the YBa 2 Cu 3 O 7-δ layers. Flux pinning energies at zero temperature and zero magnetic field in the range of 80--140 meV have been found

Growth of highly mesoporous CuCo2O4@C core-shell arrays as advanced electrodes for high-performance supercapacitors

Science.gov (United States)

Yan, Hailong; Lu, Yang; Zhu, Kejia; Peng, Tao; Liu, Xianming; Liu, Yunxin; Luo, Yongsong

2018-05-01

A series of CuCo2O4 nanostructures with different morphologies were prepared by a hydrothermal method in combination with thermal treatment. The morphology, structure and composition were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. As the electrode materials for supercapacitors, CuCo2O4 nanoneedles delivered the highest specific capacitance compared with other CuCo2O4 nanostructures. Electrochemical performance measurements demonstrate that the carbon layer can improve the electrochemical stability of CuCo2O4 nanoneedles. The CuCo2O4@C electrode exhibits a high specific capacitance of 1432.4 F g-1 at a current density of 1 A g-1, with capacitance retention of 98.2% after 3000 circles. These characteristics of CuCo2O4@C composite are mainly due to the unique one dimensional needle-liked architecture and the conducting carbon, which provide a faster ion/electron transfer rate. These excellent performances of the CuCo2O4@C electrode confirmed the material as a positive electrode for hybrid supercapacitor application.

Porous HKUST-1 derived CuO/Cu2O shell wrapped Cu(OH)2 derived CuO/Cu2O core nanowire arrays for electrochemical nonenzymatic glucose sensors with ultrahigh sensitivity

Science.gov (United States)

Yu, Cuiping; Cui, Jiewu; Wang, Yan; Zheng, Hongmei; Zhang, Jianfang; Shu, Xia; Liu, Jiaqin; Zhang, Yong; Wu, Yucheng

2018-05-01

Self-supported CuO/Cu2O@CuO/Cu2O core-shell nanowire arrays (NWAs) are successfully fabricated by a simple and efficient method in this paper. Anodized Cu(OH)2 NWAs could in-situ convert to HKUST-1 at room temperature easily. Cu(OH)2 NWAs cores and HKUST-1 shells transform into CuO/Cu2O simultaneously after calcinations and form CuO/Cu2O@CuO/Cu2O core-shell NWAs. This smart configuration of the core-shell structure not only avoids the agglomeration of the traditional MOF-derived materials in particle-shape, but also facilitates the ion diffusion and increases the active sites. This novel structure is employed as substrate to construct nonenzymatic glucose sensors. The results indicate that glucose sensor based on CuO/Cu2O@CuO/Cu2O core-shell NWAs presents ultrahigh sensitivity (10,090 μA mM-1 cm-2), low detection limit (0.48 μM) and wide linear range (0.99-1,330 μM). In addition, it also shows excellent anti-interference ability toward uric acid, ascorbic acid and L-Cysteine co-existing with glucose, good reproducibility and superior ability of real sample analysis.

Enhancement of oxidation resistance in Cu and Cu(Al) thin layers

International Nuclear Information System (INIS)

Horvath, Z.E.; Peto, G.; Paszti, Z.; Zsoldos, E.; Szilagyi, E.; Battistig, G.; Lohner, T.; Molnar, G.L.; Gyulai, J.

1999-01-01

High conductivity and good resistance to electromigration makes copper a promising interconnect material in microelectronics. However, one of its disadvantages is the poor corrosion resistance. Two methods of passivation are investigated and compared: Al alloying and BF 2 + ion implantation. X-ray diffraction (XRD) and Rutherford Backscattering Spectrometry (RBS) show the oxidation inhibition of both methods, but the different ratio of CuO 2 to CuO phases suggests different mechanisms of passivation. There are no definite oxide lines in the XRD spectrum of the implanted and annealed Cu(Al) sample, so the presence of Al and the implantation together give increased protection against oxidation. The difference between the two mechanisms of oxidation inhibition is discussed briefly

Cube Texture Formation of Cu-33at.%Ni Alloy Substrates and CeO₂ Buffer Layer for YBCO Coated Conductors

DEFF Research Database (Denmark)

Tian, Hui; Li, Suo Hong; Ru, Liang Ya

2014-01-01

Cube texture formation of Cu-33 at.%Ni alloy substartes and CeO2 buffer layer prepared by chemical solution deposition on the textured substrate were investigated by electron back scattered diffraction (EBSD) and XRD technics systematically. The results shown that a strong cube textured Cu-33at...

Raman enhancement effect on two-dimensional layered materials: graphene, h-BN and MoS2.

Science.gov (United States)

Ling, Xi; Fang, Wenjing; Lee, Yi-Hsien; Araujo, Paulo T; Zhang, Xu; Rodriguez-Nieva, Joaquin F; Lin, Yuxuan; Zhang, Jin; Kong, Jing; Dresselhaus, Mildred S

2014-06-11

Realizing Raman enhancement on a flat surface has become increasingly attractive after the discovery of graphene-enhanced Raman scattering (GERS). Two-dimensional (2D) layered materials, exhibiting a flat surface without dangling bonds, were thought to be strong candidates for both fundamental studies of this Raman enhancement effect and its extension to meet practical applications requirements. Here, we study the Raman enhancement effect on graphene, hexagonal boron nitride (h-BN), and molybdenum disulfide (MoS2), by using the copper phthalocyanine (CuPc) molecule as a probe. This molecule can sit on these layered materials in a face-on configuration. However, it is found that the Raman enhancement effect, which is observable on graphene, hBN, and MoS2, has different enhancement factors for the different vibrational modes of CuPc, depending strongly on the surfaces. Higher-frequency phonon modes of CuPc (such as those at 1342, 1452, 1531 cm(-1)) are enhanced more strongly on graphene than that on h-BN, while the lower frequency phonon modes of CuPc (such as those at 682, 749, 1142, 1185 cm(-1)) are enhanced more strongly on h-BN than that on graphene. MoS2 demonstrated the weakest Raman enhancement effect as a substrate among these three 2D materials. These differences are attributed to the different enhancement mechanisms related to the different electronic properties and chemical bonds exhibited by the three substrates: (1) graphene is zero-gap semiconductor and has a nonpolar C-C bond, which induces charge transfer (2) h-BN is insulating and has a strong B-N bond, while (3) MoS2 is semiconducting with the sulfur atoms on the surface and has a polar covalent bond (Mo-S) with the polarity in the vertical direction to the surface. Therefore, the different Raman enhancement mechanisms differ for each material: (1) charge transfer may occur for graphene; (2) strong dipole-dipole coupling may occur for h-BN, and (3) both charge transfer and dipole-dipole coupling may

A two-dimensional kinetic model of the scrape-off layer

International Nuclear Information System (INIS)

Catto, P.J.; Hazeltine, R.D.

1993-09-01

A two-dimensional (radius and poloidal angle), analytically tractable kinetic model of the ion (or energetic electron) behavior in the scrape-off layer of a limiter or divertor plasma in a tokamak is presented. The model determines the boundary conditions on the core ion density and ion temperature gradients, the power load on the limiter or divertor plates, the energy carried per particle to the walls, and the effective flux limit. The self-consistent electrostatic potential in the quasi-neutral scrape-off layer is determined by using the ion kinetic model of the layer along with a Maxwell-Boltzmann electron response that occurs because most electrons are reflected by the Debye sheaths (assumed to be infinitely thin) at the limiter or divertor plates

Device and performance parameters of Cu(In,Ga)(Se,S){sub 2}-based solar cells with varying i-ZnO layer thickness

Energy Technology Data Exchange (ETDEWEB)

Macabebe, E.Q.B. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Sheppard, C.J. [Department of Physics, University of Johannesburg, P.O. Box 524, Auckland Park 2006 (South Africa); Dyk, E.E. van, E-mail: ernest.vandyk@nmmu.ac.z [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa)

2009-12-01

In pursuit of low-cost and highly efficient thin film solar cells, Cu(In,Ga)(Se,S){sub 2}/CdS/i-ZnO/ZnO:Al (CIGSS) solar cells were fabricated using a two-step process. The thickness of i-ZnO layer was varied from 0 to 454 nm. The current density-voltage (J-V) characteristics of the devices were measured, and the device and performance parameters of the solar cells were obtained from the J-V curves to analyze the effect of varying i-ZnO layer thickness. The device parameters were determined using a parameter extraction method that utilized particle swarm optimization. The method is a curve-fitting routine that employed the two-diode model. The J-V curves of the solar cells were fitted with the model and the parameters were determined. Results show that as the thickness of i-ZnO was increased, the average efficiency and the fill factor (FF) of the solar cells increase. Device parameters reveal that although the series resistance increased with thicker i-ZnO layer, the solar cells absorbed more photons resulting in higher short-circuit current density (J{sub sc}) and, consequently, higher photo-generated current density (J{sub L}). For solar cells with 303-454 nm-thick i-ZnO layer, the best devices achieved efficiency between 15.24% and 15.73% and the fill factor varied between 0.65 and 0.67.

Crystal structures of CCa2CuO5 and CSr1.9Ca1.1Cu2O7 refined from single crystal data

International Nuclear Information System (INIS)

Kopnin, E.M.; Matveev, A.T.; Salamakha, P.S.; Sato, A.; Takayama-Muromachi, E.

2003-01-01

Single crystals were grown for new layered oxycarbonates CCa 2 CuO 5 and CSr 1.9 Ca 1.1 Cu 2 O 7 at 6 GPa using a belt-type apparatus. Their crystal structures were determined using single crystal X-ray diffraction data with R1(wR2)=0.0294(0.0659) and 0.0199(0.0457) for CCa 2 CuO 5 and CSr 1.9 Ca 1.1 Cu 2 O 7 , respectively. These phases crystallize in the space group P4/mmm (No. 123), Z=1 with a=3.8157(1) Angst, c=7.1426(3) Angst for CCa 2 CuO 5 and a=3.8753(1) Angst, c=10.6765(5) Angst for CSr 1.9 Ca 1.1 Cu 2 O 7 . In contrast to CSr 2 CuO 5 , no ordering in the orientation of the triangular CO 3 groups was revealed in CCa 2 CuO 5 and CSr 1.9 Ca 1.1 Cu 2 O 7

Hole filling and interlayer coupling in YBa2Cu3O7/PrBa2Cu3O7 superlattices

International Nuclear Information System (INIS)

Biagini, M.; Calandra, C.; Ossicini, S.

1995-01-01

Charge transfer effects in YBa 2 Cu 3 O 7 /PrBa 2 Cu 3 O 7 superlattices have been proposed by many authors as the origin of the experimentally observed strong depression of the critical temperature. We performed self-consistent LMTO-ASA calculations and found that no remarkable change in the electronic structure of the superconducting CuO 2 planes occurs in the studied structures, when the PBCO layer thickness is varied. The observed depression of the critical temperature does not seem to be originated intrinsically by a severe modification of the electronic structure or by the hole-filling mechanism. (orig.)

A two-dimensional hydrogen-bonded water layer in the structure of a cobalt(III) cubane complex.

Science.gov (United States)

Qi, Ji; Zhai, Xiang-Sheng; Zhu, Hong-Lin; Lin, Jian-Li

2014-02-01

A tetranuclear Co(III) oxide complex with cubane topology, tetrakis(2,2'-bipyridine-κ(2)N,N')di-μ2-carbonato-κ(4)O:O'-tetra-μ3-oxido-tetracobalt(III) pentadecahydrate, [Co4(CO3)2O4(C10H8N2)4]·15H2O, with an unbounded hydrogen-bonded water layer, has been synthesized by reaction of CoCO3 and 2,2'-bipyridine. The solvent water molecules form a hydrogen-bonded net with tetrameric and pentameric water clusters as subunits. The Co4O4 cubane-like cores are sandwiched between the water layers, which are further stacked into a three-dimensional metallo-supramolecular network.

Separation prediction in two dimensional boundary layer flows using artificial neural networks

International Nuclear Information System (INIS)

Sabetghadam, F.; Ghomi, H.A.

2003-01-01

In this article, the ability of artificial neural networks in prediction of separation in steady two dimensional boundary layer flows is studied. Data for network training is extracted from numerical solution of an ODE obtained from Von Karman integral equation with approximate one parameter Pohlhousen velocity profile. As an appropriate neural network, a two layer radial basis generalized regression artificial neural network is used. The results shows good agreements between the overall behavior of the flow fields predicted by the artificial neural network and the actual flow fields for some cases. The method easily can be extended to unsteady separation and turbulent as well as compressible boundary layer flows. (author)

Two-dimensional nano-lattice in Fe-Co-Ni-Al-Cu alloys

International Nuclear Information System (INIS)

Kalanov, M.U.; Ibragimova, E.M.; Khamraeva, R.N.; Rustamova, V.M.; Ummatov, H.D.

2007-01-01

Full text: The high coercive strength of the dispersionally solidified alloys on the base of Fe-Co-Ni-Al-Cu system appears as a result of the special thermomagnetic annealing, when particles of the strong magnetic phase are distinguished in non-magnetic matrix along an external magnetic field direction. The neutron studying allows one to reveal the correlation between magnetization and inclusion axes, and also existence of magnetic microcell and perfectness of the lattice. This work presents results of neutron diffraction study with a double-crystal spectrometer (0.145 nm). Plate like samples of size 18 12 4 mm 3 were cut from a single crystal of alloy UNDK35 T5 along (100) plane. Magnetic field of 6 kOe was applied perpendicular to the neutron beam. Zero-field spectrum had only random variation of the background. Under the applied magnetic field two maxima appeared at the angles of 12 and 24 minute. In the case of the magnetic field directed in parallel to the scattering vector, the two maxima disappeared as expected. It is evidence that nuclear scattering is less than magnetic one and the observed maxima correspond to (10) and (20) reflections from a two dimensional ferro-magnetic microcell. The cell parameter of the magnetic microcell was found 40.6 nm. The coherent scattering region size was 120-160 nm. The ferro-magnetic rod diameter estimated from the peak widths was 16 nm. The diffraction pattern for the demagnetized sample strongly differs from the initial magnetized sample, where a diffuse reflection was observed near Bragg reflection and related with residual magnetization. So, the magnetic inclusions created in the Fe-Co-Ni-Al-Cu system at the thermomagnetic annealing by means of disintegration of the solid solution are strong ferro-magnetic and one-domain. These particles form the two-dimensional magnetic microcell and interact each to other within 3-4 periods of the cell. (authors)

Microwave properties of YBa2Cu3O7-δ/PrBa2Cu3O7-δ superlattices

International Nuclear Information System (INIS)

Carlos, W.E.; Kaplan, R.; Lowndes, D.H.; Norton, D.P.

1992-01-01

We have used non-resonant microwave absorption to study c-axis YBa 2 Cu 3 O 7-δ /PrBa 2 Cu 3 O 7-δ superlattices and compare the response to a film of similarly grown YBa 2 Cu 3 O 7-δ (YBCO). Near the respective transition temperatures, the response of the superlattice samples and the YBCO film have similar amplitudes and orientation dependences. This is consistent with the microwave loss being related to magnetic flux penetration at (110) slip planes. At lower temperatures, the response of the superlattices is much stronger than that of the YBCO film and, while both responses are hysteretic at low temperatures, the widths of the hysteresis have opposite orientation dependences, which we attribute to the role of the PrBa 2 Cu 3 O 7-δ layers. (orig.)

Temperature dependence of positron annihilation parameters in Tl-Ba-Ca-Cu-O superconductors

International Nuclear Information System (INIS)

Sundar, C.S.; Bharathi, A.; Ching, W.Y.; Jean, Y.C.; Hor, P.H.; Meng, R.L.; Huang, Z.J.; Chu, C.W.

1990-01-01

The results of positron lifetime and Doppler broadened line-shape parameter measurements as a function of temperature, across T c , in the Tl-Ba-Ca-Cu-O superconductors are presented. The bulk lifetime in the normal state is found to decrease with the increase in the number of CuO 2 layers. Different temperature dependencies of the annihilation parameters are observed in the various Tl systems containing different numbers of CuO 2 layers. In the Tl 2 Ba 2 Ca 2 Cu 3 O 10 system, an increase in lifetime is observed below T c , whereas in Tl 2 Ba 2 CaCu 2 O 8 , a decrease in lifetime is seen below T c . In the Tl 2 Ba 2 CuO 6 system, the lifetime is observed to be temperature independent. The different temperature variations of positron annihilation parameters are discussed in the light of the positron density distribution, obtained with use of the results of the self-consistent orthogonalized linear combination of atomic orbitals band-structure calculations. It is argued that the different temperature dependencies of the annihilation parameters is related to the positron density distribution within the unit cell and arise due to local charge transfer in the vicinity of the CuO 2 layer in the superconducting state

Moisture barrier properties of single-layer graphene deposited on Cu films for Cu metallization

Science.gov (United States)

Gomasang, Ploybussara; Abe, Takumi; Kawahara, Kenji; Wasai, Yoko; Nabatova-Gabain, Nataliya; Thanh Cuong, Nguyen; Ago, Hiroki; Okada, Susumu; Ueno, Kazuyoshi

2018-04-01

The moisture barrier properties of large-grain single-layer graphene (SLG) deposited on a Cu(111)/sapphire substrate are demonstrated by comparing with the bare Cu(111) surface under an accelerated degradation test (ADT) at 85 °C and 85% relative humidity (RH) for various durations. The change in surface color and the formation of Cu oxide are investigated by optical microscopy (OM) and X-ray photoelectron spectroscopy (XPS), respectively. First-principle simulation is performed to understand the mechanisms underlying the barrier properties of SLG against O diffusion. The correlation between Cu oxide thickness and SLG quality are also analyzed by spectroscopic ellipsometry (SE) measured on a non-uniform SLG film. SLG with large grains shows high performance in preventing the Cu oxidation due to moisture during ADT.

Critical current density of strained multilayer thin films of Nd sub 1. 83 Ce sub 0. 17 CuO sub x /YBa sub 2 Cu sub 3 O sub 7 minus. delta

Energy Technology Data Exchange (ETDEWEB)

Gross, R.; Gupta, A.; Olsson, E.; Segmueller, A.; Koren, G. (IBM T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, New York 10598 (USA))

1990-07-09

The superconducting transport properties of strained multilayer thin films of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}/ Nd{sub 1.83}Ce{sub 0.17}CuO{sub {ital x}}, grown heteroepitaxially by laser ablation deposition, are reported. For individual layer thicknesses below a critical layer thickness of about 250 A, coherency strain removes the orthorhombic distortion in the YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} layers and makes them twin-free. Zero-field critical current densities as high as 1.1{times}10{sup 7} A/cm{sup 2} at 77 K have been measured for the YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} layers. Flux pinning energies at zero temperature and zero magnetic field in the range of 80--140 meV have been found.

Effects of plasma cleaning of the Cu seed layer surface on Cu electroplating

International Nuclear Information System (INIS)

O, Jun Hwan; Lee, Seong Wook; Kim, Jae Bum; Lee, Chong Mu

2001-01-01

Effects of plasma pretreatment to Cu seed/tantalum nitride (TaN)/ borophosphosilicate glass (BPSG) samples on copper (Cu) electroplating were investigated. Copper seed layers were deposited by magnetron sputtering onto tantalum nitride barrier layers before electroplating copper in the forward pulsed mode. The Cu seed layer was cleaned by plasma H 2 and N 2 prior to electroplating a copper film. Cu films electroplated on the copper seed layer with plasma pretreatment showed better electrical and physical properties such as electrical resistivities, surface morphologies, levels of impurities, adhesion and surface roughness than those without plasma pretreatment. It is shown that carbon and metal oxide contaminants at the sputtered Cu seed/TaN surface could be effectively removed by plasma H 2 cleaning. The degree of the (111) prefered orientation of the Cu film with plasma H 2 pretreatment is as high as pulse plated Cu film without plasma pretreatment. Also, plasma H 2 precleaning is more effective in enhancing the Cu electroplating properties onto the Cu seed layer than plasma N 2 precleaning

Enhancement of oxidation resistance in Cu and Cu(Al) thin layers

Energy Technology Data Exchange (ETDEWEB)

Horvath, Z.E.; Peto, G. E-mail: peto@mfa.kfki.hu; Paszti, Z.; Zsoldos, E.; Szilagyi, E.; Battistig, G.; Lohner, T.; Molnar, G.L.; Gyulai, J

1999-01-02

High conductivity and good resistance to electromigration makes copper a promising interconnect material in microelectronics. However, one of its disadvantages is the poor corrosion resistance. Two methods of passivation are investigated and compared: Al alloying and BF{sub 2}{sup +} ion implantation. X-ray diffraction (XRD) and Rutherford Backscattering Spectrometry (RBS) show the oxidation inhibition of both methods, but the different ratio of CuO{sub 2} to CuO phases suggests different mechanisms of passivation. There are no definite oxide lines in the XRD spectrum of the implanted and annealed Cu(Al) sample, so the presence of Al and the implantation together give increased protection against oxidation. The difference between the two mechanisms of oxidation inhibition is discussed briefly.

Purification of 3H-dihydroalprenolol by two dimensional thin layer chromatography

International Nuclear Information System (INIS)

Smisterova, J.; Soltes, L.; Kallay, Z.

1989-01-01

A two dimensional thin-layer chromatographic method was developed for the purification and analysis of (-)-[ 3 H]dihydroalprenolol by using an acidic mobile phase (butanol/water/acetic acid 25:10:4, v/v) in one direction and a basic eluent (chloroform/acetone/triethylamine 50:40:10, v/v) in another direction. (author)

Field-dependent antiferromagnetism and ferromagnetism of the two copper sublattices in Sr2Cu3O4Cl2

International Nuclear Information System (INIS)

Kastner, M.A.; Aharony, A.; Birgeneau, R.J.; Chou, F.C.; Entin-Wohlman, O.; Greven, M.; Harris, A.B.; Kim, Y.J.; Lee, Y.S.; Parks, M.E.; Zhu, Q.

1999-01-01

The Cu 3 O 4 layer in Sr 2 Cu 3 O 4 Cl 2 is a variant of the square CuO 2 lattice of the high-temperature superconductors, in which the center of every second plaquette contains an extra Cu 2+ ion. The ions that make up the conventional CuO 2 network, called CuI, have CuI-CuI exchange energy ∼130meV, and order antiferromagnetically at about 380 K; the CuII-CuII exchange is only ∼10meV, and the CuII close-quote s order at ∼40K. A study is reported here of the dependence of the magnetization on field, temperature, and crystallographic orientation for this interesting system. We show that the small permanent ferromagnetic moment, that appears when the CuI spins order, and the unusual spin rotation transitions seen most clearly for one particular direction of the magnetic field, are the result of several small bond-dependent anisotropic terms in the spin Hamiltonian that are revealed because of the frustration of the isotropic Heisenberg interaction between CuI and CuII spins. These include a term which favors collinearity of the CuI and CuII spins, which originates from quantum fluctuations, and also the pseudodipolar interaction. Some of these small interactions also come into play in other lamellar cuprates, connected with the high-T c superconductivity materials, and in many spin-chain and spin-ladder compounds. copyright 1999 The American Physical Society

Electrostatic assembly of Cu2O nanoparticles on DNA templates

International Nuclear Information System (INIS)

Wang Li; Wei Gang; Qi Bin; Zhou Hualan; Liu Zhiguo; Song Yonghai; Yang Xiurong; Li Zhuang

2006-01-01

In this paper, a method for highly ordered assembly of cuprous oxide (Cu 2 O) nanoparticles (NPs) by DNA templates was reported. Cetyltrimethylammonium bromide (CTAB)-capped Cu 2 O NPs were adsorbed onto well-aligned λ-DNA chains to form necklace-like one-dimensional (1D) nanostructures. UV-vis, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the nanostructure. The Cu 2 O nanostructures fabricated with the method are both highly ordered and quite straight

Interface structure and electronic properties of SrTiO3 and YBa2Cu3O7-δ crystals and thin films

International Nuclear Information System (INIS)

Thiess, S.

2007-01-01

Two new extensions of the X-ray standing wave (XSW) technique, made possible by the intense highly collimated X-ray beams from undulators at the ESRF, are described in this thesis. First, the XSW method was applied in a structural study to solve the nucleation mechanism of the high temperature superconductor YBa 2 Cu 3 O 7-δ on the (001) surface of SrTiO 3 . Second, the valence electronic structures of SrTiO 3 and YBa 2 Cu 3 O 7-δ were investigated. Finally, recent developments in the field of photoelectron spectroscopy in the hard X-ray region are described. The X-ray standing wave method is used in combination with fluorescence, Auger or photoelectron spectroscopy and lends very high spatial resolution power to these analytical techniques. Previously, the XSW method has been used for structure determination of surfaces and interfaces. The currently available X-ray intensities permit extensions to the XSW technique. Two recently established applications, described in this thesis, are XSW real space imaging and XSW valence electronic structure analysis. XSW real space imaging was employed to analyse the atomic structure of 0.5 and 1.0 layers of YBa 2 Cu 3 O 7-δ deposited on SrTiO 3 (001). Three-dimensional images of the atomic distributions were reconstructed for each of the elements from experimentally determined Fourier components of the atomic distribution functions. The images confirmed the formation of a perovskite precursor phase prior to the formation of the YBa 2 Cu 3 O 7-δ phase during the growth of the first monolayer of the film. XSW valence electronic structure analysis applied to SrTiO 3 identified the valence band contributions arising from the strontium, titanium, and oxygen sites of the crystal lattice. Relations between the site-specific valence electronic structure and the lattice structure were established. The experimental results agree very well with predictions by state-of-the-art ab initio calculations. X-ray absorption cross sections for

Punicalagin Green Functionalized Cu/Cu2O/ZnO/CuO Nanocomposite for Potential Electrochemical Transducer and Catalyst

Science.gov (United States)

Fuku, X.; Kaviyarasu, K.; Matinise, N.; Maaza, M.

2016-09-01

A novel ternary Punica granatum L-Cu/Cu2O/CuO/ZnO nanocomposite was successfully synthesised via green route. In this work, we demonstrate that the green synthesis of metal oxides is more viable and facile compare to other methods, i.e., physical and chemical routes while presenting a potential electrode for energy applications. The prepared nanocomposite was characterised by both microscopic and spectroscopic techniques. High-resolution scanning electron microscopy (HRSEM) and X-ray diffraction (XRD) techniques revealed different transitional phases with an average nanocrystallite size of 29-20 mm. It was observed that the nanocomposites changed from amorphous-slightly crystalline Cu/Cu2O to polycrystalline Cu/Cu2O/CuO/ZnO at different calcination temperatures (room temperature-RT- 600 °C). The Cu/Cu2O/ZnO/CuO metal oxides proved to be highly crystalline and showed irregularly distributed particles with different sizes. Meanwhile, Fourier transform infrared (FTIR) spectroscopy confirmed the purity while together with ultraviolet-visible (UV-Vis) spectroscopy proved the proposed mechanism of the synthesised nanocomposite. UV-Vis showed improved catalytic activity of the prepared metal oxides, evident by narrow band gap energy. The redox and electrochemical properties of the prepared nanocomposite were achieved by cyclic voltammetry (CV), electrochemical impedance (EIS) and galvanostatic charge-discharge (GCD). The maximum specific capacitance ( C s) was calculated to be 241 F g-1 at 50 mV s-1 for Cu/Cu2O/CuO/ZnO nanoplatelets structured electrode. Moreover, all the CuO nanostructures reveal better power performance, excellent rate as well as long term cycling stability. Such a study will encourages a new design for a wide spectrum of materials for smart electronic device applications.

Magnetic structure of the quasi-two-dimensional compound CoTa{sub 2}O{sub 6}

Energy Technology Data Exchange (ETDEWEB)

Kinast, E.J. [Universidade Estadual do Rio Grande do Sul, Rua 7 de Setembro, 1156, 90010-191 Porto Alegre (Brazil); Santos, C.A. dos [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, C.P. 15051, 91501-970 Porto Alegre (Brazil); Schmitt, D. [Laboratoire de Geophysique Interne et Tectonophysique, Universite Joseph Fourier, B. P. 53, 38041 Grenoble Cedex 9 (France); Isnard, O., E-mail: olivier.isnard@grenoble.cnrs.f [Institut Neel, CNRS/Universite Jospeh Fourier, avenue des martyrs B. P. 166, 38042 Grenoble Cedex 9 (France); Gusmao, M.A.; Cunha, J.B.M. da [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, C.P. 15051, 91501-970 Porto Alegre (Brazil)

2010-02-18

We report on a detailed investigation of magnetic properties of CoTa{sub 2}O{sub 6} using several techniques: neutron and X-ray diffraction, specific-heat, magnetic susceptibility, and magnetization measurements. The compound shows quasi-two-dimensional behavior due to its layered structure of alternating Co-O and Ta-O planes. We find that all magnetic moments lie entirely in the Co-O planes, along easy axes determined by the orientations of oxygen octahedra that surround the Co ions. The easy axes in successive magnetic planes have relative orientations that differ by 90{sup o}. Antiferromagnetic ordering is observed below 6.6 K, with propagation vectors ({+-}1/4,1/4,1/4) associated to the two non-equivalent sets of Co{sup 2+} ions, whose magnetic moments are perpendicularly oriented.

Microstructures and Photovoltaic Properties of Zn(AlO/Cu2O-Based Solar Cells Prepared by Spin-Coating and Electrodeposition

Directory of Open Access Journals (Sweden)

Takeo Oku

2014-03-01

Full Text Available Copper oxide (Cu2O-based heterojunction solar cells were fabricated by spin-coating and electrodeposition methods, and photovoltaic properties and microstructures were investigated. Zinc oxide (ZnO and Cu2O were used as n- and p-type semiconductors, respectively, to fabricate photovoltaic devices based on In-doped tin oxide/ZnO/Cu2O/Au heterojunction structures. Short-circuit current and fill factor increased by aluminum (Al doping in the ZnO layer, which resulted in the increase of the conversion efficiency. The efficiency was improved further by growing ZnO and Cu2O layers with larger crystallite sizes, and by optimizing the Al-doping by spin coating.

Epataxial growth of the high-temperature superconductors YBa2Cu3O7-x on silicon single crystals with buffer layers

International Nuclear Information System (INIS)

Lubig, A.

1991-09-01

In this work the growth of thin films of the high-temperature superconductor YBa 2 Cu 3 O 7-x on Si(001) substrates has been investigated by Rutherford backscattering, channeling, X-ray diffraction, high resolution transmission electron microscopy, and electrical measurements. Epitaxial buffer layers of electrically insulating, pure and yttria-stabilized ZrO 2 ([Y 2 O 3 ] 0.06 [ZrO 2 ] 0.94 = YSZ) as well as of metallic CoSi 2 were employed to largely prevent the interdiffusion and chemical reaction between the superconductor film and the substrate in spite of the high deposition temperatures of the YBa 2 Cu 3 O 7-x in the range of 600 to 800deg C. (orig.)

P-type Cu2O/SnO bilayer thin film transistors processed at low temperatures

KAUST Repository

Al-Jawhari, Hala A.

2013-10-09

P-type Cu2O/SnO bilayer thin film transistors (TFTs) with tunable performance were fabricated using room temperature sputtered copper and tin oxides. Using Cu2O film as capping layer on top of a SnO film to control its stoichiometry, we have optimized the performance of the resulting bilayer transistor. A transistor with 10 nm/15 nm Cu2O to SnO thickness ratio (25 nm total thickness) showed the best performance using a maximum process temperature of 170 C. The bilayer transistor exhibited p-type behavior with field-effect mobility, on-to-off current ratio, and threshold voltage of 0.66 cm2 V-1 s-1, 1.5×10 2, and -5.2 V, respectively. The advantages of the bilayer structure relative to single layer transistor are discussed. © 2013 American Chemical Society.

Chemical synthesis of flower-like hybrid Cu(OH)2/CuO electrode: Application of polyvinyl alcohol and triton X-100 to enhance supercapacitor performance.

Science.gov (United States)

Shinde, S K; Fulari, V J; Kim, D-Y; Maile, N C; Koli, R R; Dhaygude, H D; Ghodake, G S

2017-08-01

In this research article, we report hybrid nanomaterials of copper hydroxide/copper oxide (Cu(OH) 2 /CuO). A thin films were prepared by using a facile and cost-effective successive ionic layer adsorption and reaction (SILAR) method. As-synthesized and hybrid Cu(OH) 2 /CuO with two different surfactants polyvinyl alcohol (PVA) and triton-X 100 (TRX-100) was prepared having distinct morphological, structural, and supercapacitor properties. The surface of the thin film samples were examined by scanning electron microscopy (SEM). A nanoflower-like morphology of the Cu(OH) 2 /CuO nanostructures arranged vertically was evidenced on the stainless steel substrate. The surface was well covered by nanoflake-like morphology and formed a uniform Cu(OH) 2 /CuO nanostructures after treating with surfactants. X-ray diffraction patterns were used to confirm the hybrid phase of Cu(OH) 2 /CuO materials. The electrochemical properties of the pristine Cu(OH) 2 /CuO, PVA:Cu(OH) 2 /CuO, TRX-100:Cu(OH) 2 /CuO films were observed by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy technique. The electrochemical examination reveals that the Cu(OH) 2 /CuO electrode has excellent specific capacitance, 292, 533, and 443Fg -1 with pristine, PVA, and TRX-100, respectively in 1M Na 2 SO 4 electrolyte solution. The cyclic voltammograms (CV) of Cu(OH) 2 /CuO electrode shows positive role of the PVA and TRX-100 to enhance supercapacitor performance. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of Ag film thickness on the optical and the electrical properties in CuAlO2/Ag/CuAlO2 multilayer films grown on glass substrates

International Nuclear Information System (INIS)

Oh, Dohyun; No, Young Soo; Kim, Su Youn; Cho, Woon Jo; Kwack, Kae Dal; Kim, Tae Whan

2011-01-01

Research highlights: The CuAlO 2 /Ag/CuAlO 2 multilayer films were grown on glass substrates using radio-frequency magnetron sputtering at room temperature. Effects of Ag film thickness on the optical and the electrical properties in CuAlO 2 /Ag/CuAlO 2 multilayer films grown on glass substrates were investigated. X-ray diffraction patterns showed that the phase of the CuAlO 2 layer was amorphous. Atomic force microscopy images showed that Ag films with a thickness of a few nanometers had island structures. The morphology Ag films with a thickness of 8 nm was uniform. The morphology of the Ag films inserted in the CuAlO 2 films significantly affected the optical transmittance and the resistivity of the CuAlO 2 films deposited on glass substrates. The maximum transmittance of the CuAlO 2 /Ag/CuAlO 2 multilayer films with a thickness of 8 nm was 89.16%. The resistivity of the CuAlO 2 /Ag/CuAlO 2 multilayer films with an Ag film thickness of 18 nm was as small as about 2.8 x 10 -5 Ω cm. The resistivity of the CuAlO 2 /Ag/CuAlO 2 multilayer films was decreased as a result of the thermal annealing treatment. These results indicate that CuAlO 2 /Ag/CuAlO 2 multilayer films grown on glass substrates hold promise for potential applications as TCO films in solar cells. - Abstract: Effects of Ag film thickness on the optical and the electrical properties in CuAlO 2 /Ag/CuAlO 2 multilayer films grown on glass substrates were investigated. Atomic force microscopy images showed that Ag films with a thickness of a few nanometers had island structures. X-ray diffraction patterns showed that the phase of the CuAlO 2 layer was amorphous. The resistivity of the 40 nm-CuAlO 2 /18 nm-Ag/40 nm-CuAlO 2 multilayer films was 2.8 x 10 -5 Ω cm, and the transmittance of the multilayer films with an Ag film thickness of 8 nm was approximately 89.16%. These results indicate that CuAlO 2 /Ag/CuAlO 2 multilayer films grown on glass substrates hold promise for potential applications as

Ionic liquids-modulated two-phase thermal synthesis of three-dimensional CuS nanostructures

International Nuclear Information System (INIS)

Yao, Kaisheng; Lu, Weiwei; Li, Xinying; Wang, Jianji

2012-01-01

A novel method was proposed for successful fabrication of CuS nanostructures with various morphologies. At the ionic liquids (ILs)-modulated CHCl 3 –H 2 O interface, copper cupferronate [Cu(cup) 2 ] in CHCl 3 reacted with thiourea in water to generate CuS nanostructures via a solvothermal reaction process. The effects of alkyl chain length of imidazolium cations and nature of anions of the ILs, molar ratio of Cu(cup) 2 to thiourea, the reaction temperature and time on the morphology of the products were studied systematically. It was shown that by changing alkyl chain length of imidazolium cations and nature of anions of the ILs, CuS nanostructures with various morphologies, including flowers, urchins, large nanodisks and nanoparticles, could be obtained at the liquid–liquid interface, and the ILs played important template roles in directing the formation of CuS nanostructures. Furthermore, the as-prepared CuS samples exhibited high catalytic activity for photodegradation of methyl orange and thermal decomposition of ammonium perchlorate. - Graphical abstract: At the ionic liquids-modulated CHCl 3 –H 2 O interface, the CuS nanostructures with the various morphologies of flowers, urchins, large nanodisks and nanoparticles have been successfully prepared via a solvothermal reaction process. Highlights: ► The properties of oil–H 2 O interface can be modulated by employing different ILs. ► The modulated interface has been used to prepare CuS nanostructures with various morphologies. ► The CuS samples exhibited high catalytic activity for the photodegradation of methyl orange.

Quasi-two-dimensional electron gas at the interface of γ-Al{sub 2}O{sub 3}/SrTiO{sub 3} heterostructures grown by atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Ngo, Thong Q.; McDaniel, Martin D.; Ekerdt, John G., E-mail: ekerdt@che.utexas.edu [Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712 (United States); Goble, Nicholas J.; Gao, Xuan P. A. [Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106 (United States); Posadas, Agham; Kormondy, Kristy J.; Demkov, Alexander A. [Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States); Lu, Sirong [School of Engineering for Matter, Transport and Engineering, Arizona State University, Tempe, Arizona 85287 (United States); Jordan-Sweet, Jean [IBM T.J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Smith, David J. [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States)

2015-09-21

We report the formation of a quasi-two-dimensional electron gas (2-DEG) at the interface of γ-Al{sub 2}O{sub 3}/TiO{sub 2}-terminated SrTiO{sub 3} (STO) grown by atomic layer deposition (ALD). The ALD growth of Al{sub 2}O{sub 3} on STO(001) single crystal substrates was performed at temperatures in the range of 200–345 °C. Trimethylaluminum and water were used as co-reactants. In situ reflection high energy electron diffraction, ex situ x-ray diffraction, and ex situ cross-sectional transmission electron microscopy were used to determine the crystallinity of the Al{sub 2}O{sub 3} films. As-deposited Al{sub 2}O{sub 3} films grown above 300 °C were crystalline with the γ-Al{sub 2}O{sub 3} phase. In situ x-ray photoelectron spectroscopy was used to characterize the Al{sub 2}O{sub 3}/STO interface, indicating that a Ti{sup 3+} feature in the Ti 2p spectrum of STO was formed after 2–3 ALD cycles of Al{sub 2}O{sub 3} at 345 °C and even after the exposure to trimethylaluminum alone at 300 and 345 °C. The interface quasi-2-DEG is metallic and exhibits mobility values of ∼4 and 3000 cm{sup 2} V{sup −1} s{sup −1} at room temperature and 15 K, respectively. The interfacial conductivity depended on the thickness of the Al{sub 2}O{sub 3} layer. The Ti{sup 3+} signal originated from the near-interfacial region and vanished after annealing in an oxygen environment.

Creating Two-Dimensional Electron Gas in Nonpolar/Nonpolar Oxide Interface via Polarization Discontinuity: First-Principles Analysis of CaZrO3/SrTiO3 Heterostructure.

Science.gov (United States)

Nazir, Safdar; Cheng, Jianli; Yang, Kesong

2016-01-13

We studied strain-induced polarization and resulting conductivity in the nonpolar/nonpolar CaZrO3/SrTiO3 (CZO/STO) heterostructure (HS) system by means of first-principles electronic structure calculations. By modeling four types of CZO/STO HS-based slab systems, i.e., TiO2/CaO and SrO/ZrO2 interface models with CaO and ZrO2 surface terminations in each model separately, we found that the lattice-mismatch-induced compressive strain leads to a strong polarization in the CZO film and that as the CZO film thickness increases there exists an insulator-to-metal transition. The polarization direction and critical thickness of the CZO film for forming interfacial metallic states depend on the surface termination of CZO film in both types of interface models. In the TiO2/CaO and SrO/ZrO2 interface models with CaO surface termination, the strong polarization drives the charge transfer from the CZO film to the first few TiO2 layers in the STO substrate, leading to the formation of two-dimensional electron gas (2DEG) at the interface. In the HS models with ZrO2 surface termination, two polarization domains with opposite directions are in the CZO film, which results in the charge transfer from the middle CZO layer to the interface and surface, respectively, leading to the coexistence of the 2DEG on the interface and the two-dimensional hole gas (2DHG) at the middle CZO layer. These findings open a new avenue to achieve 2DEG (2DHG) in perovskite-based HS systems via polarization discontinuity.

Two-Dimensional SnO Anodes with a Tunable Number of Atomic Layers for Sodium Ion Batteries

KAUST Repository

Zhang, Fan; Zhu, Jiajie; Zhang, Daliang; Schwingenschlö gl, Udo; Alshareef, Husam N.

2017-01-01

We have systematically changed the number of atomic layers stacked in 2D SnO nanosheet anodes and studied their sodium ion battery (SIB) performance. The results indicate that as the number of atomic SnO layers in a sheet decreases, both

Two-Dimensional Layered Oxide Structures Tailored by Self-Assembled Layer Stacking via Interfacial Strain.

Science.gov (United States)

Zhang, Wenrui; Li, Mingtao; Chen, Aiping; Li, Leigang; Zhu, Yuanyuan; Xia, Zhenhai; Lu, Ping; Boullay, Philippe; Wu, Lijun; Zhu, Yimei; MacManus-Driscoll, Judith L; Jia, Quanxi; Zhou, Honghui; Narayan, Jagdish; Zhang, Xinghang; Wang, Haiyan

2016-07-06

Study of layered complex oxides emerge as one of leading topics in fundamental materials science because of the strong interplay among intrinsic charge, spin, orbital, and lattice. As a fundamental basis of heteroepitaxial thin film growth, interfacial strain can be used to design materials that exhibit new phenomena beyond their conventional forms. Here, we report a strain-driven self-assembly of bismuth-based supercell (SC) with a two-dimensional (2D) layered structure. With combined experimental analysis and first-principles calculations, we investigated the full SC structure and elucidated the fundamental growth mechanism achieved by the strain-enabled self-assembled atomic layer stacking. The unique SC structure exhibits room-temperature ferroelectricity, enhanced magnetic responses, and a distinct optical bandgap from the conventional double perovskite structure. This study reveals the important role of interfacial strain modulation and atomic rearrangement in self-assembling a layered singe-phase multiferroic thin film, which opens up a promising avenue in the search for and design of novel 2D layered complex oxides with enormous promise.

Soft-template-synthesis of hollow CuO/Co3O4 composites for pseudo-capacitive electrode: A synergetic effect on electrochemical performance

Science.gov (United States)

Wang, Kuaibing; Lv, Bo; Wu, Hua; Luo, Xuefei; Xu, Jiangyan; Geng, Zhirong

2016-12-01

Hollow CuO/Co3O4 hybrids, which inherited from its coordination polymer precursor consisting of sheets layer and nanoparticles layer composites, were synthesized and characterized by SEM, EDX, XRD and XPS. To assess its electrochemical capacitive performances, cyclic voltammetry, galvanostatic charging-discharging measurements and A.C. impedance tests were performed successively. The CuO/Co3O4 hybrids had higher capacitance and lower charge transfer resistance than bare Co3O4 nanostructures, revealing that it provided a protection layer and produced a synergistic effect due to the existence of CuO layer. The distinct synergistic effect could be further confirmed by endurance cycling tests. The capacitance of the CuO/Co3O4 hybrids was 111% retained after 500 cycles at a charging rate of 1.0 A g-1 and remained an intense growth trend after 2000 cycles at scan rate of 200 mV s-1.

Optical, structural and photocatalysis properties of Cu-doped TiO{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Bensouici, F., E-mail: fbensouici@yahoo.fr [Department of Physics, URMPE Unite, UMBB University, 35000 Boumerdes (Algeria); Bououdina, M.; Dakhel, A.A. [Department of Physics, College of Science, University of Bahrain, PO Box 32038 (Bahrain); Tala-Ighil, R.; Tounane, M.; Iratni, A. [Department of Physics, URMPE Unite, UMBB University, 35000 Boumerdes (Algeria); Souier, T. [Department of Physics, College of Science, Sultan Qaboos University, PO Box 36 (Oman); Liu, S.; Cai, W. [Key laboratory of Materials Physics, Anhui Key Laboratory of Nanomaterials and Technology, Center for Environmental and Energy Nanomaterials, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China)

2017-02-15

Highlights: • A simple chemical route to obtain thin layers of Cu doped TiO{sub 2}. • Detailed structure analysis was carried out by Rietveld refinements. • Forming the CuO phase decreases the efficiency photocatalysis of TiO{sub 2}. - Abstract: Pure and Cu{sup +2} doped TiO{sub 2} thin films have been successfully deposited onto glass substrate by sol–gel dip-coating. The films were annealed at 450 °C for 1 h and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM-EDX), atomic force microscopy (AFM), UV–vis spectrophotometer and photocatalytic degradation of methylene blue. XRD confirmed the presence of two phases at higher Cu concentration; TiO{sub 2} anatase and CuO. AFM analysis showed that the surface roughness increases within increasing Cu content as well as the presence of large aggregates at higher Cu content. SEM observations confirmed the granular structure of the films, and EDX analysis revealed a low solubility limit (effective doping) of Cu into TiO{sub 2} lattice. It was found that the optical band gap energy decreases with increasing Cu content. At constant irradiation time, the photo-degradation of methylene blue rate decreased with increasing concentration of Cu{sup +2}.

Two-dimensional steady unsaturated flow through embedded elliptical layers

Science.gov (United States)

Bakker, Mark; Nieber, John L.

2004-12-01

New analytic element solutions are presented for unsaturated, two-dimensional steady flow in vertical planes that include nonoverlapping impermeable elliptical layers and elliptical inhomogeneities. The hydraulic conductivity, which is represented by an exponential function of the pressure head, differs between the inside and outside of an elliptical inhomogeneity; both the saturated hydraulic conductivity and water retention parameters are allowed to differ between the inside and outside. The Richards equation is transformed, through the Kirchhoff transformation and a second standard transformation, into the modified Helmholtz equation. Analytic element solutions are obtained through separation of variables in elliptical coordinates. The resulting equations for the Kirchhoff potential consist of infinite sums of products of exponentials and modified Mathieu functions. In practical applications the series are truncated but still fulfill the differential equation exactly; boundary conditions are met approximately but up to machine accuracy, provided that enough terms are used. The pressure head, saturation, and flow may be computed analytically at any point in the vadose zone. Examples are given of the shadowing effect of an impermeable elliptical layer in a uniform flow field and funnel-type flow between two elliptical inhomogeneities. The presented solutions may be applied to study transport processes in vadose zones containing many impermeable elliptical layers or elliptical inhomogeneities.

Charge dynamics of 57Fe probe atoms in La2Li0.5Cu0.5O4

Science.gov (United States)

Presniakov, I. A.; Sobolev, A. V.; Rusakov, V. S.; Moskvin, A. S.; Baranov, A. V.

2018-06-01

The objective of this study is to characterize the electronic state and local surrounding of 57Fe Mössbauer probe atoms within iron-doped layered perovskite La2Li0.5Cu0.5O4 containing transition metal in unusual formal oxidation states "+3". An approach based on the qualitative energy diagrams analysis and the calculations within the cluster configuration interaction method have been developed. It was shown that a large amount of charge is transferred via Cu-O bonds from the O: 2p bands to the Cu: 3d orbitals and the ground state is dominated by the d9L configuration ("Cu2+-O-" state). The dominant d9L ground state for the (CuO6) sublattice induces in the environment of the 57Fe probe cations a charge transfer Fe3+ + O-(L) → Fe4+ + O2-, which transforms "Fe3+" into "Fe4+" state. The experimental spectra in the entire temperature range 77-300 K were described with the use of the stochastic two-level model based on the assumption of dynamic equilibrium between two Fe3+↔Fe4+ valence states related to the iron atom in the [Fe(1)O4]4- center. The relaxation frequencies and activation energies of the corresponding charge fluctuations were estimated based on Mössbauer data. The results are discussed assuming a temperature-induced change in the electronic state of the [CuO4]5- clusters in the layered perovskite.

Cu/Cu{sub 2}O/CuO nanoparticles: Novel synthesis by exploding wire technique and extensive characterization

Energy Technology Data Exchange (ETDEWEB)

Sahai, Anshuman [Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, A-10, Sector-62, Noida 201307 (India); Goswami, Navendu, E-mail: navendugoswami@gmail.com [Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, A-10, Sector-62, Noida 201307 (India); Kaushik, S.D. [UGC-DAE-Consortium for Scientific Research Mumbai Centre, R5 Shed, BARC, Mumbai 400085 (India); Tripathi, Shilpa [UGC-DAE Consortium for Scientific Research, Indore, M.P. (India)

2016-12-30

Highlights: The salient features of this research article are following: • Mixed phase synthesis of Cu/Cu{sub 2}O/CuO nanoparticles prepared by Exploding Wire Technique (EWT). • Predominant Cu/Cu{sub 2}O phases along with minor CuO phase revealed through XRD, TEM, Raman, FTIR, UV–Visible and PL analyses. • XPS analysis provided direct evidences of Cu{sup 2+} and Cu{sup +} along with O deficiency for prepared nanoparticles. • Room temperature weak ferromagnetic behaviour was demonstrated for Cu/Cu{sub 2}O/CuO nanoparticles. - Abstract: In this article, we explore potential of Exploding Wire Technique (EWT) to synthesize the copper nanoparticles using the copper metal in a plate and wire geometry. Rietveld refinement of X-ray diffraction (XRD) pattern of prepared material indicates presence of mixed phases of copper (Cu) and copper oxide (Cu{sub 2}O). Agglomerates of copper and copper oxide comprised of ∼20 nm average size nanoparticles observed through high resolution transmission electron microscope (HRTEM) and energy dispersive x-ray (EDX) spectroscopy. Micro-Raman (μR) and Fourier transform infrared (FTIR) spectroscopies of prepared nanoparticles reveal existence of additional minority CuO phase, not determined earlier through XRD and TEM analysis. μR investigations vividly reveal cubic Cu{sub 2}O and monoclinic CuO phases based on the difference of space group symmetries. In good agreement with μRaman analysis, FTIR stretching modes corresponding to Cu{sub 2}-O and Cu-O were also distinguished. Investigations of μR and FTIR vibrational modes are in accordance and affirm concurrence of CuO phases besides predominant Cu and Cu{sub 2}O phase. Quantum confinement effects along with increase of band gaps for direct and indirect optical transitions of Cu/Cu{sub 2}O/CuO nanoparticles are reflected through UV–vis (UV–vis) spectroscopy. Photoluminescence (PL) spectroscopy spots the electronic levels of each phase and optical transitions processes

The effects of Zn doping on magnetic properties of Cu3Bi(SeO3)2O2Cl

Science.gov (United States)

Yang, Pei-Ying; Tseng, Wu-Jyun; Wu, Hung-Cheng; Kakarla, D. Chandrasekhar; Yang, Hung-Duen; Department of Physics, Natl Sun Yat Sen Univ Team

Recently, layered spin-frustrated Cu3Bi(SeO3)2 O2Cl has received considerable research attention due to its unusual magnetic properties. Two inequivalent Cu2 + ions form a pseudo-kagome lattice that invokes spin frustration and anisotropic magnetic properties. In this study, the influence of Zn doping on the complex magnetic properties has been explored. Polycrystalline (Cu1-xZnx) Bi(SeO3)2 O2Cl (0 x 0.5) samples were synthesized using solid-state reaction and characterized by X-ray diffraction and magnetic measurements. The Zn doping strongly modulates the magnetic ground state of the system. The antiferromagnetic transition temperature TN = 24 K and magnetic field-induced hysteresis observed for x = 0 at low field are systematically shifted to lower temperature and reduced with Zn doping. These results can illustrate the insight of the occurrence of field-induced spin-flip type multiferroics in Cu3Bi(SeO3)2 O2Cl.

Band splitting and relative spin alignment in two-layer systems

CERN Document Server

Ovchinnikov, A A

2002-01-01

It is shown that the single-particle spectra of the low Hubbard zone in the two-layer correlated 2D-systems sharply differ in the case of different relative alignment of the layers spin systems. The behavior of the two-layer splitting in the Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8 sub + subdelta gives all reasons for the hypothesis on the possible rearrangement of the F sub z -> AF sub z alignment configuration, occurring simultaneously with the superconducting transition. The effects of the spin alignment on the magnetic excitations spectrum, as the way for studying the spin structure of the two-layer systems, are discussed by the example of homogenous solutions for the effective spin models

Effects of CuO nanoparticles on Lemna minor.

Science.gov (United States)

Song, Guanling; Hou, Wenhua; Gao, Yuan; Wang, Yan; Lin, Lin; Zhang, Zhiwei; Niu, Qiang; Ma, Rulin; Mu, Lati; Wang, Haixia

2016-12-01

Copper dioxide nanoparticles (NPs), which is a kind of important and widely used metal oxide NP, eventually reaches a water body through wastewater and urban runoff. Ecotoxicological studies of this kind of NPs effects on hydrophyte are very limited at present. Lemna minor was exposed to media with different concentrations of CuO NPs, bulk CuO, and two times concentration of Cu 2+ released from CuO NPs in culture media. The changes in plant growth, chlorophyll content, antioxidant defense enzyme activities [i.e., peroxidase (POD), catalase (CAT), superoxide dismutase (SOD) activities], and malondialdehyde (MDA) content were measured in the present study. The particle size of CuO NPs and the zeta potential of CuO NPs and bulk CuO in the culture media were also analyzed to complementally evaluate their toxicity on duckweed. Results showed that CuO NPs inhibited the plant growth at lower concentration than bulk CuO. L. minor roots were easily broken in CuO NPs media under the experimental condition, and the inhibition occurred only partly because CuO NPs released Cu 2+ in the culture media. The POD, SOD, and CAT activities of L. minor increased when the plants were exposed to CuO NPs, bulk CuO NPs and two times the concentration of Cu 2+ released from CuO NPs in culture media, but the increase of these enzymes were the highest in CuO NPs media among the three kinds of materials. The MDA content was significantly increased compared with that of the control from 50 mg L -1 CuO NP concentration in culture media. CuO NPs has more toxicity on L. minor compared with that of bulk CuO, and the inhibition occurred only partly because released Cu 2+ in the culture media. The plant accumulated more reactive oxygen species in the CuO NP media than in the same concentration of bulk CuO. The plant cell encountered serious damage when the CuO NP concentration reached 50 mg L -1 in culture media. The toxicology of CuO NP on hydrophytes must be considered because that hydrophytes

The flexural strength and microhardness of YBa2Cu3O6+δ

International Nuclear Information System (INIS)

Ihm, M.K.; Powell, B.R.; Bloink, R.L.

1989-01-01

The flexural strengths of rectangular YBa 2 Cu 3 O 6+δ bars, prepared from mixed oxides and carbonates, or spray dried precursors have been measured at room temperature and at 77K. Strengths ranged from 17.8 to 57.6 MPa at room temperature, depending on processing history, and were twenty percent greater when measured at 77K. Corrosion of YBa 2 Cu 3 O 6+δ in humid air at 38 0 C created two layers of corrosion products, but did not weaken the uncorroded core when failure loads were corrected for the decreased sample dimensions. The Knoop hardness of polycrystalline YBa 2 Cu 3 O 6+δ ranged from 436 to 447 KHN while the hardness of individual grains of YBa 2 Cu 3 O 6+δ was 498 KHN. Variations in flexural strength with microstructure were observed and are discussed

Interface interaction and wetting of Sc2O3 exposed to Cu-Al and Cu-Ti melts

International Nuclear Information System (INIS)

Barzilai, S.; Nagar, H.; Froumin, N.; Frage, N.; Aizenshtein, M.

2009-01-01

Scandia is a thermodynamically stable oxide and could be used as a structural material for a crucible in order to avoid a melt contamination. In the present study wetting experiments of Cu-Al and Cu-Ti melts on Scandia substrate were preformed at 1423 K by a sessile drop method. It was established that Al and Ti additions lead to the improved wetting and that the final contact angle decreases with increasing the additives concentration. For Al containing melts, the contact angle changes gradually with time, and a relatively thick interaction layer, which consists of Al 2 O 3 , Sc 2 O 3 , and metallic channels, was formed at the Sc 2 O 3 /Cu-Al interface. For Ti containing melts, the final contact angle is achieved already during heating, and an extremely thin layer based on a Ti-Sc-O compound was detected by AES at the Sc 2 O 3 /Cu-Ti interface. The results of a thermodynamic analysis, which takes into account the formation free energy of the oxides, involved in the systems, and the thermodynamic properties of the liquid solutions are in a good agreement with the experimental observations. (orig.)

Cu/Cu2O/CuO nanoparticles: Novel synthesis by exploding wire technique and extensive characterization

Science.gov (United States)

Sahai, Anshuman; Goswami, Navendu; Kaushik, S. D.; Tripathi, Shilpa

2016-12-01

In this article, we explore potential of Exploding Wire Technique (EWT) to synthesize the copper nanoparticles using the copper metal in a plate and wire geometry. Rietveld refinement of X-ray diffraction (XRD) pattern of prepared material indicates presence of mixed phases of copper (Cu) and copper oxide (Cu2O). Agglomerates of copper and copper oxide comprised of ∼20 nm average size nanoparticles observed through high resolution transmission electron microscope (HRTEM) and energy dispersive x-ray (EDX) spectroscopy. Micro-Raman (μR) and Fourier transform infrared (FTIR) spectroscopies of prepared nanoparticles reveal existence of additional minority CuO phase, not determined earlier through XRD and TEM analysis. μR investigations vividly reveal cubic Cu2O and monoclinic CuO phases based on the difference of space group symmetries. In good agreement with μRaman analysis, FTIR stretching modes corresponding to Cu2-O and Cu-O were also distinguished. Investigations of μR and FTIR vibrational modes are in accordance and affirm concurrence of CuO phases besides predominant Cu and Cu2O phase. Quantum confinement effects along with increase of band gaps for direct and indirect optical transitions of Cu/Cu2O/CuO nanoparticles are reflected through UV-vis (UV-vis) spectroscopy. Photoluminescence (PL) spectroscopy spots the electronic levels of each phase and optical transitions processes occurring therein. Iterative X-ray photoelectron spectroscopy (XPS) fitting of core level spectra of Cu (2p3/2) and O (1s), divulges presence of Cu2+ and Cu+ in the lattice with an interesting evidence of O deficiency in the lattice structure and surface adsorption. Magnetic analysis illustrates that the prepared nanomaterial demonstrates ferromagnetic behaviour at room temperature.

Assembly of 1D nanofibers into a 2D bi-layered composite nanofibrous film with different functionalities at the two layers via layer-by-layer electrospinning.

Science.gov (United States)

Wang, Zijiao; Ma, Qianli; Dong, Xiangting; Li, Dan; Xi, Xue; Yu, Wensheng; Wang, Jinxian; Liu, Guixia

2016-12-21

A two-dimensional (2D) bi-layered composite nanofibrous film assembled by one-dimensional (1D) nanofibers with trifunctionality of electrical conduction, magnetism and photoluminescence has been successfully fabricated by layer-by-layer electrospinning. The composite film consists of a polyaniline (PANI)/Fe 3 O 4 nanoparticle (NP)/polyacrylonitrile (PAN) tuned electrical-magnetic bifunctional layer on one side and a Tb(TTA) 3 (TPPO) 2 /polyvinylpyrrolidone (PVP) photoluminescent layer on the other side, and the two layers are tightly combined face-to-face together into the novel bi-layered composite film of trifunctionality. The brand-new film has totally different characteristics at the double layers. The electrical conductivity and magnetism of the electrical-magnetic bifunctional layer can be, respectively, tunable via modulating the PANI and Fe 3 O 4 NP contents, and the highest electrical conductivity can reach up to the order of 10 -2 S cm -1 , and predominant intense green emission at 545 nm is obviously observed in the photoluminescent layer under the excitation of 357 nm single-wavelength ultraviolet light. More importantly, the luminescence intensity of the photoluminescent layer remains almost unaffected by the electrical-magnetic bifunctional layer because the photoluminescent materials have been successfully isolated from dark-colored PANI and Fe 3 O 4 NPs. By comparing with the counterpart single-layered composite nanofibrous film, it is found that the bi-layered composite nanofibrous film has better performance. The novel bi-layered composite nanofibrous film with trifunctionality has potential in the fields of nanodevices, molecular electronics and biomedicine. Furthermore, the design conception and fabrication technique for the bi-layered multifunctional film provide a new and facile strategy towards other films of multifunctionality.

Two-Dimensional Layered Double Hydroxide Derived from Vermiculite Waste Water Supported Highly Dispersed Ni Nanoparticles for CO Methanation

Directory of Open Access Journals (Sweden)

Panpan Li

2017-03-01

Full Text Available Expanded multilayered vermiculite (VMT was successfully used as catalyst support and Ni/VMT synthesized by microwave irradiation assisted synthesis (MIAS exhibited excellent performance in our previous work. We also developed a two-dimensional porous SiO2 nanomesh (2D VMT-SiO2 by mixed-acid etching of VMT. Compared with three-dimensional (3D MCM-41, 2D VMT-SiO2 as a catalyst support provided a superior position for implantation of NiO species and the as-obtained catalyst exhibited excellent performance. In this paper, we successfully synthesized a layered double hydroxide (LDH using the spent liquor after mixed-acid etching of VMT, which mainly contained Mg2+ and Al3+. The as-calcined layered double oxide (LDO was used as a catalyst support for CO methanation. Compared with Ni/MgAl-LDO, Ni/VMT-LDO had smaller active component particles; therefore, in this study, it exhibited excellent catalytic performance over the whole temperature range of 250–500 °C. Ni/VMT-LDO achieved the best activity with 87.88% CO conversion, 89.97% CH4 selectivity, and 12.47 × 10−2·s−1 turn over frequency (TOF at 400 °C under a gas hourly space velocity of 20,000 mL/g/h. This study demonstrated that VMT-LDO as a catalyst support provided an efficient way to develop high-performance catalysts for synthetic natural gas (SNG from syngas.

Crystal growth of YBa2Cu3O(7-x) and reaction of gold crucible with Ba-Cu-rich flux

Science.gov (United States)

Tao, Y. K.; Chen, H. C.; Martini, L.; Bechtold, J.; Huang, Z. J.; Hor, P. H.

1991-01-01

YBa2Cu3O(7-x) crystals are grown in a gold crucible by a self-flux method. The flux moves along the gold surface due to surface wetting and leaves Y123 crystals behind. The obtained crystals are clean and have a size up to two millimeters and a Tc is greater than 90 K. In an effort to recycle the used crucibles, it is found that the used gold is contaminated by copper. A CuO thin film is easily formed on the surface of the crucible that is made of the used gold. This film provides good surface wetting and a buffer layer, which reduces the reaction between gold and the Y-Ba-Cu-oxide melt.

Novel interplay between high-Tc superconductivity and antiferromagnetism in Tl-Based Six-CuO2-layered cuprates. 205Tl- and 63Cu-NMR probes

International Nuclear Information System (INIS)

Mukuda, Hidekazu; Shiki, Nozomu; Kimoto, Naoki; Yashima, Mitsuharu; Kitaoka, Yoshio; Tokiwa, Kazuyasu; Iyo, Akira

2016-01-01

We report 63 Cu- and 205 Tl-NMR studies on six-layered (n = 6) high-T c superconducting (SC) cuprate TlBa 2 Ca 5 Cu 6 O 14+δ (Tl1256) with T c ∼ 100 K, which reveal that antiferromagnetic (AFM) order takes place below T N ∼ 170 K. In this compound, four underdoped inner CuO 2 planes [n(IP) = 4] sandwiched by two outer planes (OPs) are responsible for the onset of AFM order, whereas the nearly optimally-doped OPs responsible for the onset of bulk SC. It is pointed out that an increase in the out-of-plane magnetic interaction within an intra-unit-cell causes T N ∼ 45 K for Tl1245 with n(IP) = 3 to increase to ∼170 K for Tl1256 with n(IP) = 4. It is remarkable that the marked increase in T N and the AFM moments for the IPs does not bring about any reduction in T c , since T c ∼ 100 K is maintained for both compounds with nearly optimally doped OP. We highlight the fact that the SC order for n ≥ 5 is mostly dominated by the long-range in-plane SC correlation even in the multilayered structure, which is insensitive to the magnitude of T N and the AFM moments at the IPs or the AFM interaction among the IPs. These results demonstrate a novel interplay between the SC and AFM orders when the charge imbalance between the IPs and OP is significantly large. (author)

Electroless deposition of NiCrB diffusion barrier layer film for ULSI-Cu metallization

Energy Technology Data Exchange (ETDEWEB)

Wang, Yuechun [School of Materials Science and Engineering, Yunnan University, Kunming (China); Chen, Xiuhua, E-mail: chenxh@ynu.edu.cn [School of Materials Science and Engineering, Yunnan University, Kunming (China); Ma, Wenhui [National Engineering Laboratory of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming (China); Shang, Yudong; Lei, Zhengtao; Xiang, Fuwei [School of Materials Science and Engineering, Yunnan University, Kunming (China)

2017-02-28

Highlights: • In this paper, the electroless deposited NiCrB thin film was mainly in the form of NiB, CrB{sub 2} compounds and elementary Ni. • The sheet resistance of NiCrB thin film was 3.043 Ω/□, it is smaller than that of the widely used Ta, TaN and TiN diffusion barrier layers. • Annealing experiments showed that the failure temperature of NiCrB thin film regarding Cu diffusion was 900 °C. • NiCrB barrier layer crystallized after 900 °C annealing, Cu grains arrived at Si-substrate through grain boundaries, resulting in the formation of Cu{sub 3}Si. • Eelectroless deposited NiCrB film also had good oxidation resistance, it is expected to become an anti-oxidant layer of copper interconnection. - Abstract: NiCrB films were deposited on Si substrates using electroless deposition as a diffusion barrier layer for Cu interconnections. Samples of the prepared NiCrB/SiO{sub 2}/Si and NiCrB/Cu/NiCrB/SiO{sub 2}/Si were annealed at temperatures ranging from 500 °C to 900 °C. The reaction mechanism of the electroless deposition of the NiCrB film, the failure temperature and the failure mechanism of the NiCrB diffusion barrier layer were investigated. The prepared samples were subjected to XRD, XPS, FPP and AFM to determine the phases, composition, sheet resistance and surface morphology of samples before and after annealing. The results of these analyses indicated that the failure temperature of the NiCrB barrier film was 900 °C and the failure mechanism led to crystallization and grain growth of the NiCrB barrier layer after high temperature annealing. It was found that this process caused Cu grains to reach Si substrate through the grain boundaries, and then the reaction between Cu and Si resulted in the formation of highly resistive Cu{sub 3}Si.

Interfacial engineering of two-dimensional nano-structured materials by atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Zhuiykov, Serge, E-mail: serge.zhuiykov@ugent.be [Ghent University Global Campus, Department of Applied Analytical & Physical Chemistry, Faculty of Bioscience Engineering, 119 Songdomunhwa-ro, Yeonsu-Gu, Incheon 406-840 (Korea, Republic of); Kawaguchi, Toshikazu [Global Station for Food, Land and Water Resources, Global Institution for Collaborative Research and Education, Hokkaido University, N10W5 Kita-ku, Sapporo, Hokkaido 060-0810 (Japan); Graduate School of Environmental Science, Hokkaido University, N10W5 Kita-ku, Sapporo, Hokkaido 060-0810 (Japan); Hai, Zhenyin; Karbalaei Akbari, Mohammad; Heynderickx, Philippe M. [Ghent University Global Campus, Department of Applied Analytical & Physical Chemistry, Faculty of Bioscience Engineering, 119 Songdomunhwa-ro, Yeonsu-Gu, Incheon 406-840 (Korea, Republic of)

2017-01-15

Highlights: • Advantages of atomic layer deposition technology (ALD) for two-dimensional nano-crystals. • Conformation of ALD technique and chemistry of precursors. • ALD of semiconductor oxide thin films. • Ultra-thin (∼1.47 nm thick) ALD-developed tungsten oxide nano-crystals on large area. - Abstract: Atomic Layer Deposition (ALD) is an enabling technology which provides coating and material features with significant advantages compared to other existing techniques for depositing precise nanometer-thin two-dimensional (2D) nanostructures. It is a cyclic process which relies on sequential self-terminating reactions between gas phase precursor molecules and a solid surface. ALD is especially advantageous when the film quality or thickness is critical, offering ultra-high aspect ratios. ALD provides digital thickness control to the atomic level by depositing film one atomic layer at a time, as well as pinhole-free films even over a very large and complex areas. Digital control extends to sandwiches, hetero-structures, nano-laminates, metal oxides, graded index layers and doping, and it is perfect for conformal coating and challenging 2D electrodes for various functional devices. The technique’s capabilities are presented on the example of ALD-developed ultra-thin 2D tungsten oxide (WO{sub 3}) over the large area of standard 4” Si substrates. The discussed advantages of ALD enable and endorse the employment of this technique for the development of hetero-nanostructure 2D semiconductors with unique properties.

Mode I type delamination fracture toughness of YBCO coated conductor with additional Cu layer

International Nuclear Information System (INIS)

Miyazato, T.; Hojo, M.; Sugano, M.; Adachi, T.; Inoue, Y.; Shikimachi, K.; Hirano, N.; Nagaya, S.

2011-01-01

A fracture toughness test method was developed for a YBCO coated conductor with an additional Cu layer. Mode I type tests were carried out using double cantilever beam (DCB) specimens. Delamination propagated into the YBCO layer, and sometimes reached the Ag/YBCO interface. The fracture toughness for YBCO was about 10 J/m 2 . That for Ag/YBCO interface was about 100 J/m 2 . Although interlaminar fracture at a YBa 2 Cu 3 O 7-δ (YBCO)/CeO 2 interface was reported for YBCO coated conductors, this has not yet been investigated by a fracture mechanical approach. In the present study, we developed a mode I type fracture toughness test method for a YBCO coated conductor with an additional Cu layer using double cantilever beam (DCB) specimens. Fracture mechanism was investigated by microscopic observation by a scanning electron microscope (SEM), together with composition analysis by an energy dispersive X-ray spectroscope (EDS). A pre-crack introduced at the YBCO/CeO 2 interface deviated from the interface, and propagated into the YBCO layer, and sometimes reached the Ag/YBCO interface. The fracture toughness, G R , for YBCO and the Ag/YBCO interface was evaluated to be 7-10 J/m 2 and 80-120 J/m 2 , respectively. The complex stress intensity factor ratio, K 2 /K 1 , at YBCO/CeO 2 interface was evaluated to be -0.19, and this ratio controlled the formation of microcracks in the YBCO layer. The main crack propagated into the YBCO layer accompanied with the formation of microcracks.

YBCO/manganite layered structures on NdGaO3 substrates

International Nuclear Information System (INIS)

Nurgaliev, T; Blagoev, B; Donchev, T; Miteva, S; Mozhaev, P B; Mozhaeva, J E; Ovsyannikov, G A; Kotelyanskii, I M; Jacobsen, C

2006-01-01

Results of deposition of YBa 2 Cu 3 O 7-x /CeO 2 /(La 0.7 Ca 0.3 MnO 3 or La 0.7 Sr 0.3 MnO 3 ) structures on the standard oriented and tilted ( 8 0 ) NdGaO 3 substrates and results of investigation of electrical parameters of YBa 2 Cu 3 O 7-x (YBCO) films in such structures are presented. The YBCO component of the structure exhibits lower value of the critical parameters in comparison with those of single YBCO films. The contribution of the magnetic layer to the microwave losses of the YBCO film in the layered structure is evaluated

Synthesis of core-shell heterostructured Cu/Cu2O nanowires monitored by in situ XRD as efficient visible-light photocatalysts

KAUST Repository

Chen, Wei

2013-01-01

Core-shell heterostructured Cu/Cu2O nanowires with a high aspect ratio were synthesized from Cu foam using a novel oxidation/reduction process. In situ XRD was used as an efficient tool to acquire phase transformation details during the temperature-programmed oxidation of Cu foam and the subsequent reduction process. Based on knowledge of the crucial phase transformation, optimal synthesis conditions for producing high-quality CuO and core-shell Cu/Cu2O nanowires were determined. In favor of efficient charge separation induced by the special core-shell heterostructure and the advanced three-dimensional spatial configuration, Cu/Cu2O nanowires exhibited superior visible-light activity in the degradation of methylene blue. The present study illustrates a novel strategy for fabricating efficiently core-shell heterostructured nanowires and provides the potential for developing their applications in electronic devices, for environmental remediation and in solar energy utilization fields. This journal is © The Royal Society of Chemistry.

Organic photovoltaic effects depending on CuPc layer thickness

International Nuclear Information System (INIS)

Hur, Sung Woo; Kim, Tae Wan; Chung, Dong Hoe; Oh, Hyun Seok; Kim, Chung Hyeok; Lee, Joon Ung; Park, Jong Wook

2004-01-01

Organic photovoltaic effects were studied in device structures of ITO/CuPc/Al and ITO/CuPc/C 60 /BCP/Al by varying the CuPc layer thickness. Since the exciton diffusion length is relatively short in organic semiconductors, a study on the thickness-dependent photovoltaic effects is important. The thickness of the CuPc layer was varied from 10 nm to 50 nm. We found that the optimum CuPc layer thickness was around 40 nm from the analysis of the current density-voltage characteristics in an ITO/CuPc/Al photovoltaic cell. The efficiency of the device shows that the multi-layered heterojunction structure is more appropriate for photovoltaic cells.

Isolation of a new two-dimensional honeycomb carbonato-bridged copper(II) complex exhibiting long-range ferromagnetic ordering.

Science.gov (United States)

Majumder, Arpi; Choudhury, Chirantan Roy; Mitra, Samiran; Rosair, Georgina M; El Fallah, M Salah; Ribas, Joan

2005-04-28

Atmospheric CO2 fixation by an aqueous solution containing Cu(ClO4)2.6H2O and 4-aminopyridine (4-apy) yields a novel example of a two-dimensional mu3-CO3 bridged copper(II) complex {[Cu(4-apy)2]3(mu3-CO3)2(ClO4)2.(1/2)CH3OH}n that has been characterized by IR, UV and X-ray crystallography; preliminary magnetic measurements show that complex exhibits long-range ordered ferromagnetic coupling.

Resistive and magnetoresistive properties of BiSrCaCuO granulated films

International Nuclear Information System (INIS)

Mal'tsev, V.A.; Kulikovskij, A.V.; Kustikov, E.V.; Morozov, D.Yu.; Sokolov, Yu.S.

1995-01-01

Transport properties of superconducting bridges produced by laser etching of granulated films BiSrCaCuO have been studied. Analysis of nonlinear voltammetric characteristics of the bridges permits making the conclusion on the change in the character of conductivity (two-dimensional-three dimensional system), when approaching the critical point. Measurements of magnetoresistance of the samples suggest a possibility of application of high-temperature superconducting bridges in Bi-system as sensors of weak magnetic fields. 11 refs.; 4 figs

Relationship between superconducting transition temperature and number of CuO2 layers in mercury-based superconductors

International Nuclear Information System (INIS)

Chen Xiaojia; Xu Zhuan; Jiao Zhengkuan; Zhang Qirui

1997-01-01

The nonmonotonic dependence of the superconducting transition temperature on the number of CuO 2 layers (n) per unit cell for mercury-based cuprate systems is investigated with the framework of the electrostatic model and the Ginsburg-Landau theory. It is found that the largest value of the normalized density of states is 1.8 when n=3, which corresponds to the highest T c in this series. Using reasonable parameters we predict an upper limit of T c of 160 K. (orig.)

Electronic structure studies of La2CuO4

International Nuclear Information System (INIS)

Wachs, A.L.; Turchi, P.E.A.; Jean, Y.C.

1988-01-01

We report results of positron-electron momentum-distribution measurements of single-crystal La 2 CuO 4 using two-dimensional angular correlation of positron-annihilation-radiation techniques. The data contain two components: a large (∼85%), isotropic corelike electron contribution and a remaining, anisotropic valence-electron contribution modeled using a linear combination of atomic orbitals--molecular orbital method and a localized ion scheme, within the independent-particle model approximation. This work suggests a ligand-field Hamiltonian to be justified for describing the electronic properties of perovskite materials

Electronic structure studies of La2CuO4

Science.gov (United States)

Wachs, A. L.; Turchi, P. E. A.; Jean, Y. C.; Wetzler, K. H.; Howell, R. H.; Fluss, M. J.; Harshman, D. R.; Remeika, J. P.; Cooper, A. S.; Fleming, R. M.

1988-07-01

We report results of positron-electron momentum-distribution measurements of single-crystal La2CuO4 using two-dimensional angular correlation of positron-annihilation-radiation techniques. The data contain two components: a large (~85%), isotropic corelike electron contribution and a remaining, anisotropic valence-electron contribution modeled using a linear combination of atomic orbitals-molecular orbital method and a localized ion scheme, within the independent-particle model approximation. This work suggests a ligand-field Hamiltonian to be justified for describing the electronic properties of perovskite materials.

Soft-template-synthesis of hollow CuO/Co{sub 3}O{sub 4} composites for pseudo-capacitive electrode: A synergetic effect on electrochemical performance

Energy Technology Data Exchange (ETDEWEB)

Wang, Kuaibing, E-mail: wangkb@njau.edu.cn [Department of Chemistry, College of Science, Nanjing Agricultural University, Nanjing 210095 (China); State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, Nanjing University, Nanjing 210093 (China); Lv, Bo; Wu, Hua; Luo, Xuefei; Xu, Jiangyan [Department of Chemistry, College of Science, Nanjing Agricultural University, Nanjing 210095 (China); Geng, Zhirong [State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, Nanjing University, Nanjing 210093 (China)

2016-12-15

Hollow CuO/Co{sub 3}O{sub 4} hybrids, which inherited from its coordination polymer precursor consisting of sheets layer and nanoparticles layer composites, were synthesized and characterized by SEM, EDX, XRD and XPS. To assess its electrochemical capacitive performances, cyclic voltammetry, galvanostatic charging-discharging measurements and A.C. impedance tests were performed successively. The CuO/Co{sub 3}O{sub 4} hybrids had higher capacitance and lower charge transfer resistance than bare Co{sub 3}O{sub 4} nanostructures, revealing that it provided a protection layer and produced a synergistic effect due to the existence of CuO layer. The distinct synergistic effect could be further confirmed by endurance cycling tests. The capacitance of the CuO/Co{sub 3}O{sub 4} hybrids was 111% retained after 500 cycles at a charging rate of 1.0 A g{sup −1} and remained an intense growth trend after 2000 cycles at scan rate of 200 mV s{sup −1}. - Graphical abstract: Hollow CuO/Co{sub 3}O{sub 4} hybrids are synthesized and display a peculiar synergetic effect on the resulting performances, which can further be evaluated and confirmed by series of electrochemical measurements. - Highlights: • Hollow CuO/Co{sub 3}O{sub 4} hybrids are synthesized from bimetallic-Schiff base polymer precursors. • The capacitance of the CuO/Co{sub 3}O{sub 4} hybrids keeps a growth tendency after 2000 cycles. • A synergetic effect is found for the hybrids in electrochemical energy storage process.

High performance top-gated ferroelectric field effect transistors based on two-dimensional ZnO nanosheets

Science.gov (United States)

Tian, Hongzheng; Wang, Xudong; Zhu, Yuankun; Liao, Lei; Wang, Xianying; Wang, Jianlu; Hu, Weida

2017-01-01

High quality ultrathin two-dimensional zinc oxide (ZnO) nanosheets (NSs) are synthesized, and the ZnO NS ferroelectric field effect transistors (FeFETs) are demonstrated based on the P(VDF-TrFE) polymer film used as the top gate insulating layer. The ZnO NSs exhibit a maximum field effect mobility of 588.9 cm2/Vs and a large transconductance of 2.5 μS due to their high crystalline quality and ultrathin two-dimensional structure. The polarization property of the P(VDF-TrFE) film is studied, and a remnant polarization of >100 μC/cm2 is achieved with a P(VDF-TrFE) thickness of 300 nm. Because of the ultrahigh remnant polarization field generated in the P(VDF-TrFE) film, the FeFETs show a large memory window of 16.9 V and a high source-drain on/off current ratio of more than 107 at zero gate voltage and a source-drain bias of 0.1 V. Furthermore, a retention time of >3000 s of the polarization state is obtained, inspiring a promising candidate for applications in data storage with non-volatile features.

Magnetic properties of layered oxysulfide (LnO)CuS:Ln = La, Pr, Nd

International Nuclear Information System (INIS)

Nakao, H.; Takano, Y.; Takase, K.; Sato, K.; Hara, S.; Ikeda, S.; Takahashi, Y.; Sekizawa, K.

2006-01-01

We have prepared rare earth oxysulfides (PrO)CuS and (NdO)CuS in order to introduce magnetic moments into the non-magnetic p-type semiconductor (LaO)CuS. Both compounds are semiconductors with high electrical resistivity, and show the paramagnetic behavior. The temperature dependence of the magnetic susceptibility is well explained by the trivalent rare earth ion. However, it deviates from simple Curie Wiess law below 100 K due to the crystal field effect on rare earth ions. We have succeeded to reproduce their magnetic properties by the calculation taking the crystal field effect into account using the operator equivalent method

Optical excitations in CuO2-sheets doped and undoped with electrons

International Nuclear Information System (INIS)

Tokura, Y.; Arima, T.; Koshihara, S.; Takagi, H.; Ido, T.; Ishibashi, S.; Uchida, S.

1989-01-01

This paper reports optical reflectance spectra measured on single crystals of parent families of high T c copper oxide compounds with single-layered CuO 2 -sheets, which clearly show the strong transitons across the charge-transfer (CT) gaps at 1.5-2.0 eV in various types of CuO 2 -sheets. The carrier-doping effects on the CT excitations have been investigated on the Sr-doped La 2 CuO 4 and Ce-doped Nd 2 O 4 crystals

Optical Two Dimensional Fourier Transform Spectroscopy of Layered Metal Dichalcogenides

Science.gov (United States)

Dey, P.; Paul, J.; Stevens, C. E.; Kovalyuk, Z. D.; Kudrynskyi, Z. R.; Romero, A. H.; Cantarero, A.; Hilton, D. J.; Shan, J.; Karaiskaj, D.; Z. D. Kovalyuk; Z. R. Kudrynskyi Collaboration; A. H. Romero Collaboration; A. Cantarero Collaboration; D. J. Hilton Collaboration; J. Shan Collaboration

2015-03-01

Nonlinear two-dimensional Fourier transform (2DFT) measurements were used to study the mechanism of excitonic dephasing and probe the electronic structure of the excitonic ground state in layered metal dichalcogenides. Temperature-dependent 2DFT measurements were performed to probe exciton-phonon interactions. Excitation density dependent 2DFT measurements reveal exciton-exciton and exciton-carrier scattering, and the lower limit for the homogeneous linewidth of excitons on positively and negatively doped samples. U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-SC0012635.

Epitaxial growth and properties of YBaCuO thin films

International Nuclear Information System (INIS)

Geerk, J.; Linker, G.; Meyer, O.

1989-08-01

The growth quality of YBaCuO thin films deposited by sputtering on different substrates (Al 2 O 3 , MgO, SrTiO 3 , Zr(Y)O 2 ) has been studied by X-ray diffraction and channeling experiments as a function of the deposition temperature. Besides the substrate orientation, the substrate temperature is the parameter determining whether films grow in c-, a-, (110) or mixed directions. Epitaxial growth correlates with high critical current values in the films of up to 5.5x10 6 A/cm 2 at 77 K. Ultrathin films with thicknesses down to 2 nm were grown revealing three-dimensional superconducting behaviour. Films on (100) SrTiO 3 of 9 nm thickness and below are partially strained indicating commensurate growth. From the analysis of the surface disorder 1 displaced Ba atom per Ba 2 Y row was obtained indicating that the disordered layer thickness is about 0.6 nm. Tunnel junctions fabricated on these films reveal gap-like structures near ±16 mV and ±30 mV. (orig.) [de

Positron-annihilation studies on the YBa2Cu4O8 superconductor

International Nuclear Information System (INIS)

Sundar, C.S.; Bharathi, A.; Jean, Y.C.; Hor, P.H.; Meng, R.L.; Xue, Y.Y.; Huang, Z.J.; Chu, C.W.

1990-01-01

Positron-lifetime and Doppler-broadened annihilation-radiation line-shape parameter S in YBa 2 Cu 4 O 8 are observed to decrease with temperature below T c . The calculation of the positron-density distribution shows that the maximum of the positron density is in the region between the Cu-O double chains. The correlation between the temperature dependence of annihilation parameters and the positron-density distribution is discussed. The decrease in annihilation parameters below T c is understood in terms of a local electron transfer from the CuO 2 layers to the Cu-O chains in the superconducting state

Opto-electronic properties and light-emitting device application of widegap layered oxychalcogenides: LaCuOCh (Ch=chalcogen) and La2CdO2Se2

International Nuclear Information System (INIS)

Hiramatsu, Hidenori; Hirano, Masahiro; Kamioka, Hayato; Ueda, Kazushige; Ohta, Hiromichi; Kamiya, Toshio; Hosono, Hideo

2006-01-01

Electronic and optical properties of widegap oxychalcogenides, LaCuOCh (Ch chalcogen) and La 2 CdO 2 Se 2 , are reviewed with a focus on those relevant to their layered crystal structures, including high hole mobility, degenerate p-type conduction, room temperature exciton, and large third order optical nonlinearity. In particular, the widegap p-type metallic conduction was realized in Mg-doped LaCuOSe: the first demonstration among any class of widegap materials including GaN:Mg. Furthermore, we demonstrate the room temperature operation of a blue light-emitting diode using a pn hetero-junction composed of a LaCuOSe epilayer and an n-type amorphous InGaZn 5 O 8 . Those results strongly suggest that a series of the layered oxychalcogenides are applicable to the light-emitting layers in opto-electronic devices that operate in the ultraviolet-blue region as well as to transparent p-type conductors. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (Abstract Copyright [2006], Wiley Periodicals, Inc.)

Modified band alignment effect in ZnO/Cu2O heterojunction solar cells via Cs2O buffer insertion

Science.gov (United States)

Eom, Kiryung; Lee, Dongyoon; Kim, Seunghwan; Seo, Hyungtak

2018-02-01

The effects of a complex buffer layer of cesium oxide (Cs2O) on the photocurrent response in oxide heterojunction solar cells (HSCs) were investigated. A p-n junction oxide HSC was fabricated using p-type copper (I) oxide (Cu2O) and n-type zinc oxide (ZnO); the buffer layer was inserted between the Cu2O and fluorine-doped tin oxide (FTO). Ultraviolet-visible (UV-vis) and x-ray and ultraviolet photoelectron spectroscopy analyses were performed to characterize the electronic band structures of cells, both with and without this buffer layer. In conjunction with the measured band electronic structures, the significantly improved visible-range photocurrent spectra of the buffer-inserted HSC were analyzed in-depth. As a result, the 1 sun power conversion efficiency was increased by about three times by the insertion of buffer layer. The physicochemical origin of the photocurrent enhancement was mainly ascribed to the increased photocarrier density in the buffer layer and modified valence band offset to promote the effective hole transfer at the interface to FTO on the band-alignment model.

Synthesis and magnetic properties of hexagonal Y(Mn,Cu)O3 multiferroic materials

International Nuclear Information System (INIS)

Jeuvrey, L.; Peña, O.; Moure, A.; Moure, C.

2012-01-01

Single-phase hexagonal-type solid solutions based on the multiferroic YMnO 3 material were synthesized by a modified Pechini process. Copper doping at the B-site (YMn 1−x Cu x O 3 ; x 1+y MnO 3 ; y 3+ two-dimensional lattice. The magnetic transition at T N decreases from 70 K down to 49 K, when x(Cu) goes from 0 to 15 at%. Weak ferromagnetic Mn 3+ –Mn 4+ interactions created by the substitution of Mn 3+ by Cu 2+ , are visible through the coercive field and spontaneous magnetization but do not modify the overall magnetic frustration. Presence of Mn 3+ –Mn 4+ pairs leads to an increase of the electrical conductivity due to thermally-activated small-polaron hopping mechanisms. Results show that local ferromagnetic interactions can coexist within the frustrated state in the hexagonal polar structure. - Highlights: ► Hexagonal-type solid solutions of Y(Mn,Cu)O 3 synthesized by Pechini process. ► Chemical substitution at B site inhibits geometrical magnetic frustration. ► Magnetic transition decreases with Cu-doping. ► Local ferromagnetic Mn–Mn interactions coexist with the frustrated state.

Three-dimensional superconductivity and vortex glass transition in La1.87Y0.13CuO4

International Nuclear Information System (INIS)

Lee, Hyun-Sook; Kim, Heon-Jung; Kim, Hyun-Jung; Jung, Myung-Hwa; Jo, Younghun; Lee, Sung-Ik; Tsukada, Akio; Naito, Michio

2006-01-01

The angular dependence of the critical current density (J c (θ)) and the vortex glass transition temperature (T g (θ)) in La 1.87 Y 0.13 CuO 4 were measured at different fields and temperatures. Both J c (θ) and T g (θ) showed a strong angular variation, which is typical for anisotropic superconductors. The angular variation could be described by using the anisotropic three-dimensional Ginzburg-Landau theory. From our analysis, we were able to estimate the anisotropy ratio

Tuning the Two-Dimensional Electron Gas at Oxide Interfaces with Ti-O Configurations: Evidence from X-ray Photoelectron Spectroscopy

DEFF Research Database (Denmark)

Zhang, Yu; Gan, Yulin; Niu, Wei

2018-01-01

Chemical redox reaction can lead to a two-dimensional electron gas (2DEG) at the interface between a TiO2-terminated SrTiO3 (STO) substrate and an amorphous LaAlO3 (a-LAO) capping layer. When replacing the STO substrate with rutile and anatase TiO2 substrates, considerable differences...... in interfacial conduction are observed. Based on X-ray photoelectron spectroscopy (XPS) and transport measurements, we conclude that the interfacial conduction comes from redox reactions, and that the differences among the materials systems result mainly from variations in the activation energies...

Luminescence of two-dimensional ordered array of the ZnO quantum nanodots, obtained by means of the synthetic opal

International Nuclear Information System (INIS)

Gruzintsev, A.N.; Volkov, V.T.; Emelchenko, G.A.; Karpov, I.A.; Maslov, W.M.; Michailov, G.M.; Yakimov, E.E.

2004-01-01

The luminescence properties of ZnO films of different thickness obtained on a synthetic opal were investigated. Several narrow peaks in the exciton emission region related to the size quantum effect of the electron wave functions were detected. Two-dimensional ordered array of ZnO quantum dots formed inside the opal pores on the second sphere layer were found by the atomic force microscopy (AFM) and angle dependence of the luminescence spectra

Two-dimensional thermoelectric Seebeck coefficient of SrTiO3-based superlattices

International Nuclear Information System (INIS)

Ohta, Hiromichi

2008-01-01

This review provides the origin of the unusually large thermoelectric Seebeck coefficient vertical stroke S vertical stroke of a two-dimensional electron gas confined within a unit cell layer thickness (∝0.4 nm) of a SrTi 0.8 Nb 0.2 O 3 layer of artificial superlattices of SrTiO 3 /SrTi 0.8 Nb 0.2 O 3 [H. Ohta et al., Nature Mater. 6, 129 (2007)]. The vertical stroke S vertical stroke 2D values of the[(SrTiO 3 ) 17 /(SrTi 0.8 Nb 0.2 O 3 ) y ] 20 superlattice increase proportional to y -0.5 , and reach 290 μV K -1 (y=1) at room temperature, which is ∝5 times larger than that of the SrTi 0.8 Nb 0.2 O 3 bulk (vertical stroke S vertical stroke 3D =61 μVK -1 ), proving that the density of states in the ground state for SrTiO 3 increases in inverse proportion to y. The critical barrier thickness for quantum electron confinement is also clarified to be 6.25 nm (16 unit cells of SrTiO 3 ). Significant structural changes are not observed in the superlattice after annealing at 900 K in a vacuum. The value of vertical stroke S vertical stroke 2D of the superlattice gradually increases with temperature and reaches 450 μVK -1 at 900 K, which is ∝3 times larger than that of bulk SrTi 0.8 Nb 0.2 O 3 . These observations provide clear evidence that the [(SrTiO 3 ) 17 /(SrTi 0.8 Nb 0.2 O 3 ) 1 ] 20 superlattice is stable and exhibits a giant vertical stroke S vertical stroke even at high temperature. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Synthesis and characterization of 64SiO2-26CaO-5P2O5-5CuO bioactive composition for the growth of hydroxyapatite layer by XRD, Raman and pH studies

Science.gov (United States)

Kaur, Pardeep; Singh, K. J.

2016-05-01

Bioactive sample with the nominal composition of 64SiO2-26CaO-5P2O5-5CuO has been prepared in the laboratory by using the sol-gel technique. The bioactivity of the prepared sample has been analyzed by using the Tris Simulated Body Fluid which has also been prepared in the laboratory. XRD and Raman techniques have been employedto probe the formation of hydroxyapatite layer. pH studies has also been undertaken to check the acidic/non-acidic behavior of sample. Growth of hydroxyapatite layer has been observed after one day on the surface of the sample. Moreover, sample has been observed to be non-acidic in nature.

Proximity-effect and tunneling in YBa2Cu3O7/metal layered structures

International Nuclear Information System (INIS)

Greene, L.H.; Feldmann, W.L.; Barner, J.B.; Farrow, L.A.; Miceli, P.F.; Ramesh, R.; Wilkens, B.J.; Bagley, B.G.; Giroud, M.; Rowell, J.M.

1990-01-01

Superconducting thin films of YBa 2 Cu 3 O 7 are prepared in-situ by on-axis sputter deposition from a single, composite target. The planar magnetron target composition of YBa:Cu = 1.08:1.76:4.5 sputtered onto MgO at T ∼ 750 degrees C in a 600 mTorr Ar-O 2 atmosphere yields reproducible superconducting films having T c (R = 0) > 80 K and stoichiometry 1:2:3, that are shiny and of near epitaxial crystalline quality. In order to ensure clean interfaces, YBa 2 Cu 3 O 7 /normal metal bilayers (to form SNS' Josephson junctions) and YBa 2 Cu 3 O 7 /normal metal/insulating barrier trilayers (to form SNIS' proximity tunnel junctions) are grown completely in-situ. (The S' = Pb counter electrode is evaporated ex-situ.) A supercurrent and Shapiro steps are observed in microwave irradiated SNS' (N = Ag) small area (5 x 10 -5 cm 2 junctions. In SNIS' tunnel junctions, high-quality Pb tunnelling is observed

Sensors of the gas CO in thin film of SnO{sub 2}:Cu; Sensores del gas CO en pelicula delgada de SnO{sub 2}:Cu

Energy Technology Data Exchange (ETDEWEB)

Tirado G, S.; Sanchez Z, F. E., E-mail: tirado@esfm.ipn.mx [IPN, Escuela Superior de Fisica y Matematicas, Unidad Profesional Adolfo Lopez Mateos, San Pedro Zacatenco, 07738 Mexico D. F. (Mexico)

2011-10-15

Thin films of SnO{sub 2}:Cu with different thickness, were deposited on soda-lime glass substrates and prepared by the Sol-gel process and repeated immersion. The sensor properties of these films to the gas CO for the range of 0-200 ppm in the gas concentration and operating to temperatures of 23, 100, 200, and 300 C were studied. Prepared films of pure SnO{sub 2} were modified superficially with 1, 3, 5 and 10 layers of the catalyst Cu (SnO{sub 2}:Cu) with the purpose of studying the effect on the sensor capacity of the gas CO by part of the films SnO{sub 2}:Cu. Using the changes in the electric properties of the films with the incorporation of the different copper layers and experimental conditions, the sensor modifications of the gas CO were evaluated. To complete this study, was realized a characterization of the superficial morphology of the films by scanning electron microscopy and atomic force microscopy, equally was studied their structure and their electric and optical properties. (Author)

Deuterium transport in Cu, CuCrZr, and Cu/Be

Science.gov (United States)

Anderl, R. A.; Hankins, M. R.; Longhurst, G. R.; Pawelko, R. J.

This paper presents the results of deuterium implantation/permeation experiments and TMAP4 simulations for a CuCrZr alloy, for OFHC-Cu and for a Cu/Be bi-layered structure at temperatures from 700 to 800 K. Experiments used a mass-analyzed, 3-keV D 3+ ion beam with particle flux densities of 5 × 10 19 to 7 × 10 19 D/m 2 s. Effective diffusivities and surface molecular recombination coefficients were derived giving Arrhenius pre-exponentials and activation energies for each material: CuCrZr alloy, (2.0 × 10 -2 m 2/s, 1.2 eV) for diffusivity and (2.9 × x10 -14 m 4/s, 1.92 eV) for surface molecular recombination coefficients; OFHC Cu, (2.1 × 10 -6 m 2/s, 0.52 eV) for diffusivity and (9.1 × 10 -18 m 4/s, 0.99 eV) for surface molecular recombination coefficients. TMAP4 simulation of permeation data measured for a Cu/Be bi-layer sample was achieved using a four-layer structure (Cu/BeO interface/Be/BeO back surface) and recommended values for diffusivity and solubility in Be, BeO and Cu.