High-pressure modifications of CaZn2, SrZn2, SrAl2, and BaAl2: Implications for Laves phase structural trends

International Nuclear Information System (INIS)

Kal, Subhadeep; Stoyanov, Emil; Belieres, Jean-Philippe; Groy, Thomas L.; Norrestam, Rolf; Haeussermann, Ulrich

2008-01-01

High-pressure forms of intermetallic compounds with the composition CaZn 2 , SrZn 2 , SrAl 2 , and BaAl 2 were synthesized from CeCu 2 -type precursors (CaZn 2 , SrZn 2 , SrAl 2 ) and Ba 21 Al 40 by multi-anvil techniques and investigated by X-ray powder diffraction (SrAl 2 and BaAl 2 ), X-ray single-crystal diffraction (CaZn 2 ), and electron microscopy (SrZn 2 ). Their structures correspond to that of Laves phases. Whereas the dialuminides crystallize in the cubic MgCu 2 (C15) structure, the dizincides adopt the hexagonal MgZn 2 (C14) structure. This trend is in agreement with the structural relationship displayed by sp bonded Laves phase systems at ambient conditions. - Graphical abstract: CeCu 2 -type polar intermetallics can be transformed to Laves phases upon simultaneous application of pressure and temperature. The observed structures are controlled by the valence electron concentration

RECONSTRUCTION OF CALCINED Zn -Al LAYERED DOUBLE HYDROXIDES DURING TETRACYCLINE ADSORPSION

Directory of Open Access Journals (Sweden)

G. M. Starukh

2015-12-01

Full Text Available Zn-Al mixed oxides containing ZnO different degree crystallinity were obtained by calcinations of Zn-Al layered double hydroxides (LDHs. The reconstruction of calcined Zn-Al LDHs has been performed under stirring in aqueous suspensions. The assynthesized LDHs, its decomposition products, as well as the reconstructed solids upon hydration were characterized by XRD, N2adsorption, differential and thermal gravimetric analysis. It was found that the ability of Zn-Al LDHs to recover a layered structure under the hydration of mixed oxides depends on the degree of ZnO crystallinity. The partial reconstruction of Zn-Al layered structure occurs in tetracycline solutions irrespective to the degree of ZnO crystallinity in calcined LDHs. Calcined Zn-Al LDHs demonstrate the higher adsorption capacity to tetracycline in comparison with as-prepared Zn-Al LDHs. The adsorption of TC on calcined and uncalcined ZnAl LDHs occurs on the centers of one particular type. It is suggested that surface complexation of the A-ring ligand of TC with Al-OH centers takes place.

Al-doped ZnO seed layer-dependent crystallographic control of ZnO nanorods by using electrochemical deposition

Energy Technology Data Exchange (ETDEWEB)

Son, Hyo-Soo; Choi, Nak-Jung [Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung 429-793 (Korea, Republic of); Kim, Kyoung-Bo [Department of Metallurgical and Materials Engineering, Inha Technical College, Incheon 402-752 (Korea, Republic of); Kim, Moojin [Department of Renewable Energy, Jungwon University, Goesan-gun, Chungbuk 367-805 (Korea, Republic of); Lee, Sung-Nam, E-mail: snlee@kpu.ac.kr [Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung 429-793 (Korea, Republic of)

2016-10-15

Highlights: • Polar and semipolar ZnO NRs were successfully achieved by hydrothermal synthesis. • Semipolar and polar ZnO NRs were grown on ZnO and AZO/m-sapphire, respectively. • Al % of AZO/m-sapphire enhanced the lateral growth rate of polar ZnO NRs. - Abstract: We investigated the effect of an Al-doped ZnO film on the crystallographic direction of ZnO nanorods (NRs) using electrochemical deposition. From high-solution X-ray diffraction measurements, the crystallographic plane of ZnO NRs grown on (1 0 0) ZnO/m-plane sapphire was (1 0 1). The surface grain size of the (100) Al-doped ZnO (AZO) film decreased with increasing Al content in the ZnO seed layer, implying that the Al dopant accelerated the three-dimensional (3D) growth of the AZO film. In addition, it was found that with increasing Al doping concentration of the AZO seed layer, the crystal orientation of the ZnO NRs grown on the AZO seed layer changed from [1 0 1] to [0 0 1]. With increasing Al content of the nonpolar (1 0 0) AZO seed layer, the small surface grains with a few crystallographic planes of the AZO film changed from semipolar (1 0 1) ZnO NRs to polar (0 0 1) ZnO NRs due to the increase of the vertical [0 0 1] growth rate of the ZnO NRs owing to excellent electrical properties.

Deviations from cooperative growth mode during eutectoid transformation: Insights from a phase-field approach

International Nuclear Information System (INIS)

Ankit, Kumar; Mukherjee, Rajdip; Mittnacht, Tobias; Nestler, Britta

2014-01-01

The non-cooperative eutectoid transformation relies on the presence of pre-existing cementite particles in the parent austenitic phase and yields a product, popularly known as the divorced eutectoid. Under isothermal conditions, two of the important parameters that influence the transformation mechanism and determine the final morphology are undercooling (below the A 1 temperature) and interparticle spacing. Although the criteria that govern the morphological transition from lamellar to divorced is experimentally well established, numerical studies giving a detailed exposition of the non-cooperative transformation mechanism have not been reported extensively. In the present work, we employ a multiphase-field model that uses thermodynamic information from the CALPHAD database to numerically simulate the pulling-away of the advancing ferrite–austenite interface from cementite, which results in a transition from lamellar to divorced eutectoid morphology in Fe–C alloy. We also identify the onset of a concurrent growth and coarsening regime at small interparticle spacing and low undercooling. We analyze the simulation results to unravel the essential physics behind this complex spatial and temporal evolution pathway and amend the existing criteria by constructing a Lamellar-Divorced-Coarsening (LDC) map

Synthesis of High Crystalline Al-Doped ZnO Nanopowders from Al2O3 and ZnO by Radio-Frequency Thermal Plasma

Directory of Open Access Journals (Sweden)

Min-Kyeong Song

2015-01-01

Full Text Available High crystalline Al-doped ZnO (AZO nanopowders were prepared by in-flight treatment of ZnO and Al2O3 in Radio-Frequency (RF thermal plasma. Micron-sized (~1 μm ZnO and Al2O3 powders were mixed at Al/Zn ratios of 3.3 and 6.7 at.% and then injected into the RF thermal plasma torch along the centerline at a feeding rate of 6.6 g/min. The RF thermal plasma torch system was operated at the plate power level of ~140 kVA to evaporate the mixture oxides and the resultant vapor species were condensed into solid particles by the high flow rate of quenching gas (~7000 slpm. The FE-SEM images of the as-treated powders showed that the multipod shaped and the whisker type nanoparticles were mainly synthesized. In addition, these nanocrystalline structures were confirmed as the single phase AZO nanopowders with the hexagonal wurtzite ZnO structure by the XRD patterns and FE-TEM results with the SAED image. However, the composition changes of 0.3 and 1.0 at.% were checked for the as-synthesized AZO nanopowders at Al/Zn ratios of 3.3 and 6.7 at.%, respectively, by the XRF data, which can require the adjustment of Al/Zn in the mixture precursors for the applications of high Al doping concentrations.

Aluminum-doped Zn O polycrystalline films prepared by co-sputtering of a Zn O-Al target

Energy Technology Data Exchange (ETDEWEB)

Becerril, M.; Silva L, H.; Guillen C, A.; Zelaya A, O. [Instituto Politecnico Nacional, Centro de Investigacion y de Estudios Avanzados, Departamento de Fisica, Apdo. Postal 14-740, 07000 Mexico D. F. (Mexico)

2014-07-01

Aluminum-doped Zinc oxide polycrystalline thin films (Azo) were grown on 7059 Corning glass substrates at room temperature by co-sputtering from a Zn O-Al target. The target was designed as follows, high purity elemental Aluminum was evaporated onto a Zn O target covering small areas. The structural, optical and electrical properties were analyzed as a function of Al content. The Al doped Zn O polycrystalline films showed an n-type conductivity. It was found that the electrical resistivity drops and the carrier concentration increases as a consequence of Al incorporation within the Zn O lattice. In both cases, the changes are of several orders of magnitude. From the results, we conclude that, using these Zn O-Al targets, n-type Al doped Zn O polycrystalline films with high transmittance and low resistivity can be obtained. The crystalline structure of the films was determined by X-ray diffraction. Atomic Force Microscopy images were obtained with an Auto probe C P (Veeco Metrology Group) Microscope. (Author)

Characteristics of mechanical alloying of Zn-Al-based alloys

International Nuclear Information System (INIS)

Zhu, Y.H.; Hong Kong Polytechnic; Perez Hernandez, A.; Lee, W.B.

2001-01-01

Three pure elemental powder mixtures of Zn-22%Al-18%Cu, Zn-5%Al-11%Cu, and Zn-27%Al-3%Cu (in wt.%) were mechanically alloyed by steel-ball milling processing. The mechanical alloying characteristics were investigated using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques. It was explored that mechanical alloying started with the formation of phases from pure elemental powders, and this was followed by mechanical milling-induced phase transformation. During mechanical alloying, phases stable at the higher temperatures formed at the near room temperature of milling. Nano-structure Zn-Al-based alloys were produced by mechanical alloying. (orig.)

Improved photoluminescence property of CTAB assisted polyaniline-AlZnO nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Mitra, Mousumi; Banerjee, Dipali, E-mail: dipalibanerjeebesu@gmail.com [Department of Physics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah (India); Kargupta, Kajari [Department of Chemical Engineering, Jadavpur University, Kolkata (India); Ganguly, Saibal [Chemical Engineering department, Universiti Teknology Petronas, Tronoh (Malaysia)

2015-06-24

Polyaniline-Al doped ZnO ((PANI-AlZnO:: 70:30) nanocomposite was prepared via in situ chemical oxidative polymerization, while the hexagonal powder of AlZnO was synthesized via sol-gel technique, using Hexadecyltrimethylammonium bromide (CTAB) as a capping agent. The prepared nanocomposite was characterized by High resolution transmission electron microscopy (HRTEM), EDAX, X-ray diffraction (XRD) and Fourier transforms infrared (FTIR) spectra. The optical property of the nanomaterials is examined by photoluminescence (PL) spectra analysis. The XRD pattern confirms the formation of Al doped ZnO as well as PANI. The HRTEM images of the composite showed the formation of hexagonal AlZnO embedded in polyaniline matrix. EDAX spectrum shows the compositional analysis of the nanocomposite. FTIR spectra confirm the formation of nanocomposite of PANI and hexagonal AlZnO. The PL intensity of the nanocomposite is improved as compared to pure AlZnO.

One-pot synthesis of Cu/ZnO/ZnAl2O4 catalysts and their catalytic performance in glycerol hydrogenolysis

KAUST Repository

Tan, Hua

2013-01-01

In this work, a series of Cu/ZnO/ZnAl2O4 catalysts with different metal molar fractions (Cu:Zn:Al) were successfully prepared using a one-pot method via the evaporation-induced self-assembly (EISA) of Pluronic P123 and the corresponding metal precursors. The catalysts were characterized using N2 adsorption, H2 temperature-programmed reduction (H2-TPR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectra (XPS). The catalytic properties of the resulting Cu/ZnO/ZnAl2O4 with different molar fractions of metals were investigated for the selective hydrogenolysis of glycerol to 1,2-propanediol (1,2-PDO). It was observed that the ZnAl2O 4 support exerts a strong positive effect on the catalytic activity of the copper-based catalysts, and the presence of ZnO further improves the catalytic activity of the Cu/ZnAl2O4 catalysts. The Cu/ZnO/ZnAl2O4 catalyst (Cu10Zn 30Al60, Cu/Zn/Al molar ratio is 10:30:60), which was the best catalyst, exhibited the highest yield (79%) of 1,2-PDO with 85.8% glycerol conversion and 92.1% 1,2-PDO selectivity at 180 °C reaction temperature in 80 wt% glycerol aqueous solution over 10 h reaction time. The high catalytic activity was attributed to the presence of the ZnAl2O4 support, the strong interaction between ZnO and Cu nanoparticles and the small particle size of ZnO and Cu. Moreover, the Cu/ZnO/ZnAl2O4 catalysts exhibited higher stability than Cu/ZnO and Cu/ZnO/Al2O 3 catalysts prepared by a co-precipitation method during consecutive cycling experiments, which is due to the high chemical and thermal stability of crystalline ZnAl2O4 under harsh reaction conditions. This journal is © The Royal Society of Chemistry.

Preparation, optical properties of ZnO, ZnO:Al nanorods and Y(OH)3:Eu nanotube

International Nuclear Information System (INIS)

Tran Kim Anh; Dinh Xuan Loc; Lam thi Kieu Giang; Le Quoc Minh; Strek, Wieslaw

2009-01-01

ZnO, ZnO:Al nanorods and Y(OH) 3 nanotubes have been prepared by the chemical vapor deposition and liquid phase synthesis. ZnO nanorods with diameter of 50 - 100 nm and length of 5 μm have been obtained by the CVD method. ZnO:Al nanorods were synthesized by the hydrothermal method from ZnSO 4. and Al 2 (SO 4 ) 3 . Nanorods and nanotubes of Y(OH) 3 with diameter of 200 nm and length of several micrometers were prepared by the soft template method. The crystal structure and morphology of rods and tubes were analyzed by the X-Ray diffraction and FE-SEM. The influence of fabrication conditions and Al, Eu concentration have been discussed.

Elastocaloric effect in CuAlZn and CuAlMn shape memory alloys under compression

OpenAIRE

Qian, Suxin; Geng, Yunlong; Wang, Yi; Pillsbury, Thomas E.; Hada, Yoshiharu; Yamaguchi, Yuki; Fujimoto, Kenjiro; Hwang, Yunho; Radermacher, Reinhard; Cui, Jun; Yuki, Yoji; Toyotake, Koutaro; Takeuchi, Ichiro

2016-01-01

This paper reports the elastocaloric effect of two Cu-based shape memory alloys: Cu68Al16Zn16 (CuAlZn) and Cu73Al15Mn12 (CuAlMn), under compression at ambient temperature. The compression tests were conducted at two different rates to approach isothermal and adiabatic conditions. Upon unloading at a strain rate of 0.1 s−1 (adiabatic condition) from 4% strain, the highest adiabatic temperature changes (ΔTad) of 4.0 K for CuAlZn and 3.9 K for CuAlMn were obtained. The maximum stress and hystere...

Ultraviolet Sensing by Al-doped ZnO Thin Films

International Nuclear Information System (INIS)

Rashid, A.R.A.; Menon, P.S.; Shaari, S.

2011-01-01

We report the fabrication and characterization of an ultraviolet photoconductive sensing by using Al-doped ZnO films. Undoped ZnO, 1 at.% and 2 at% of Al were prepared on quartz glass by sol gel method with annealing temperature of 500 degree Celsius for 1 hour. The presence of spherical shaped nanoparticles were detected for undoped ZnO by using FESEM. The absorption edge shifted to a lower wavelength by doping with Al and excitonic peak can be observed. The band gap values increased by adding Al. I-V curves reveal an improvement in electrical properties when the samples are illuminated by ultraviolet (UV) light with a wavelength of 365 nm. At 1 at.% of Al, the film have a larger increment in photocurrent response when illuminated with UV light compared to undoped ZnO and 2 at.% Al. The thin films have a longer recovery time than response time. (author)

Fabrication of Al doped ZnO films using atmospheric pressure cold plasma

International Nuclear Information System (INIS)

Suzaki, Yoshifumi; Miyagawa, Hayato; Yamaguchi, Kenzo; Kim, Yoon-Kee

2012-01-01

Under atmospheric pressure, homogeneous non-equilibrium cold plasma was generated stably by high voltage pulsed power (1 kV, 20 kHz, 38 W) excitation of a mixture of He and O 2 gases produced by a dielectric barrier discharge setup. By feeding Bis (2 methoxy‐6-methyl‐3, 5-heptanedione) Zn (Zn-MOPD, C 18 H 3 O 6 Zn) and Tris (2-methoxy‐6‐methy l‐3, 5-heptanedione) Al (Al-MOPD, C 27 H 45 O 9 Al) into this plasma with He carrier gas, transparent flat Al-doped ZnO (ZnO:Al) films about 120–240 nm thick were prepared on glass substrates directly under the slit made into the cathode. Deposition rates of the films were about 20–40 nm/min. The concentration of Al was measured by inductively coupled plasma atomic emission spectroscopy. The composition ratio of Al to Zn was 7.8 mol% when the carrier He gas flow rate of Al-MOPD was 30 cm 3 . The average transmittance of all films was more than 85% in the wavelength range from 400 to 800 nm. When the composition ratio of Al/Zn was between 1.1 and 7.8 mol%, the optical band gap of the film increased from 3.28 to 3.40 eV. The resistivity of ZnO:Al film was 2.96 Ω cm at 1.3 mol% of Al/Zn. In addition, the microstructure of the films was studied by X-ray diffraction measurement and field emission scanning electron microscope observation. It was revealed that doped Al is substituted onto the Zn site of the ZnO crystalline structure in ZnO:Al films. - Highlights: ► An atmospheric pressure cold plasma generator generated stable glow discharge. ► We fabricated Al doped ZnO films on glass substrates using cold plasma. ► Al concentration measured by inductively coupled plasma atomic emission spectroscopy. ► The transmission spectrum and the resistivity of the films were measured. ► The microstructure of the films was studied.

Monotectic four-phase reaction in Al-Bi-Zn alloys

Energy Technology Data Exchange (ETDEWEB)

Groebner, J. [Clausthal University of Technology, Institute of Metallurgy, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany); Mirkovic, D. [Clausthal University of Technology, Institute of Metallurgy, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany); Schmid-Fetzer, R. [Clausthal University of Technology, Institute of Metallurgy, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany)]. E-mail: schmid-fetzer@tu-clausthal.de

2005-06-15

Thermodynamic phase diagram calculations were used for the systematic search for a monotectic four-phase reaction in ternary Al-alloys. Systems with intermetallic phases and also the elements Cd and Hg were excluded in the present search. The ternary Al-Bi-Zn is a rare occasion where such a reaction, L' = L' + (Al)' + (Zn), actually occurs. Experimental work could be focused on key samples in that system and involved DSC for thermal analysis and calorimetry, and also metallographic analysis using SEM/EDX. Experimental results verify the existence of the monotectic reaction and were also used for a quantitative thermodynamic modeling of Al-Bi-Zn. Solidification paths and microstructures of Al-Bi-Zn alloys are shown to be rather complex. Using thermodynamic calculations, these rich details involving up to three invariant reactions and unexpected monovariant reaction types can be clearly revealed and understood.

Atomic layer deposition of Al-doped ZnO thin films

Energy Technology Data Exchange (ETDEWEB)

Tynell, Tommi; Yamauchi, Hisao; Karppinen, Maarit; Okazaki, Ryuji; Terasaki, Ichiro [Department of Chemistry, Aalto University, FI-00076 Aalto (Finland); Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)

2013-01-15

Atomic layer deposition has been used to fabricate thin films of aluminum-doped ZnO by depositing interspersed layers of ZnO and Al{sub 2}O{sub 3} on borosilicate glass substrates. The growth characteristics of the films have been investigated through x-ray diffraction, x-ray reflection, and x-ray fluorescence measurements, and the efficacy of the Al doping has been evaluated through optical reflectivity and Seebeck coefficient measurements. The Al doping is found to affect the carrier density of ZnO up to a nominal Al dopant content of 5 at. %. At nominal Al doping levels of 10 at. % and higher, the structure of the films is found to be strongly affected by the Al{sub 2}O{sub 3} phase and no further carrier doping of ZnO is observed.

HYDROTALSIT Zn-Al-EDTA SEBAGAI ADSORBEN UNTUK POLUTAN ION Pb(II DI LINGKUNGAN Zn-Al-EDTA Hydrotalcite as Adsorbent for Pb(II Ion Pollutant in The Environment

Directory of Open Access Journals (Sweden)

Roto Roto

2015-07-01

Full Text Available ABSTRAK Polusi ion Pb(II di dalam lingkungan perairan cenderung naik seiring peningkatan jumlah industri smelter dan daur ulang aki bekas. Penelitian ini bertujuan untuk menguji kemampuan hidrotalsit Zn-Al-EDTA sebagai adsorben ion Pb(II dalam air secara mendalam. Hidrotalsit Zn-Al-NO3 disintesis dengan metode kopresipitasi dan hidrotermal pada temperatur 100 °C selama 15 jam. Hidrotalsit Zn-Al-EDTA diperoleh dengan penukaran ion. Keasaman larutan, kinetika dan kapasitas adsorpsi diteliti. Hidrotalsit Zn-Al-EDTA memiliki d003 sebesar 14,52 Å sementara Zn-Al-NO3 sebesar 8,90 Å. Spektra FTIR menunjukkan keberadaan serapan gugus C=O pada bilangan gelombang 1684,77 cm-1. Kondisi optimum adsorpsi ion Pb(II terjadi pada pH 4, waktu kontak 60 menit dan kapasitas adsorpsi diperoleh 2,07 mg/g pada konsentrasi awal 10 mg/L dengan berat adsorben 0,100 g. Adsorpsi ion Pb(II oleh hidrotalsit Zn-Al-EDTA mengikuti reaksi pseudo orde dua dengan tetapan laju adsorpsi sebesar 8,90 g mmol-1min-1. Adsorpsi ion Pb(II oleh Zn-Al-EDTA terjadi karena  pembentukan khelat Pb-EDTA di dalam struktur hidrotalsit. Hasil ini diharapkan mampu memberikan kontribusi yang lebih luas di dalam pengendalian konsentrasi Pb(II di lingkungan. ABSTRACT Polution by Pb(II ion in the water environment tends to increase due the increase in the number of lead smelter and lead acid battery recycling industries. This work aims at studying in details the ability of Zn-Al-EDTA hydrotalcite as adsorbent for Pb(II ion in the environment. The Zn-Al-NO3 hydrotalcite was synthesized first by coprecipitation method followed by hydrothermal treatment at 100 °C for 15 h. The Zn-Al-EDTA hydrotalcite was later obtained by ion exchange process. The solution pH, kinetics and adsorption capacity were studied. The XRD data showed that Zn-Al-EDTA and Zn-Al-NO3 hydrotalcites have d003 of 14.52 and 8.90 Å, respectively. The FTIR spectra suggested that C=O group was observed with absorption band at 1684

Preparation, structural and optical characterization of ZnO, ZnO: Al nanopowder

Energy Technology Data Exchange (ETDEWEB)

Mohan, R. Raj [Department of ECE, Gojan School of Business and Technology, Chennai (India); Rajendran, K. [Department of Electronics, Government Arts College for Women, Ramanathapuram, TN (India); Sambath, K. [Department of ECS, Sri Krishna Arts and Science College, Coimbatore, TN (India)

2014-01-28

In this paper, ZnO and ZnO:Al nanopowders have been synthesized by low cost hydrothermal method. Zinc nitrate, hexamethylenetetramine (HMT) and aluminium nitrate are used as precursors for ZnO and AZO with different molar ratios. The structural and optical characterization of doped and un-doped ZnO powders have been investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDAX), photoluminescence (PL) and ultra violet visible (UV-Vis) absorption studies. The SEM results show that the hydrothermal synthesis can be used to obtain nanoparticles with different morphology. It is observed that the grain size of the AZO nanoparticles increased with increasing of Al concentration. The PL measurement of AZO shows that broad range of green emission around 550nm with high intensity. The green emission resulted mainly because of intrinsic defects.

Preparation, optical properties of ZnO, ZnO:Al nanorods and Y(OH){sub 3}:Eu nanotube

Energy Technology Data Exchange (ETDEWEB)

Tran Kim Anh; Dinh Xuan Loc; Lam thi Kieu Giang; Le Quoc Minh [Institute of Materials Science, Vietnamese Academy of Science and Technology 18 Hoang Quoc Viet, Nghia Do, Cau Giay, Hanoi (Viet Nam); Strek, Wieslaw [Institute of Low Temperature and Structure Research, PAN, 2 Okolna, Wroclaw (Poland)], E-mail: kimanh1949@gmail.com

2009-01-01

ZnO, ZnO:Al nanorods and Y(OH){sub 3} nanotubes have been prepared by the chemical vapor deposition and liquid phase synthesis. ZnO nanorods with diameter of 50 - 100 nm and length of 5 {mu}m have been obtained by the CVD method. ZnO:Al nanorods were synthesized by the hydrothermal method from ZnSO{sub 4.} and Al{sub 2}(SO{sub 4}){sub 3}. Nanorods and nanotubes of Y(OH){sub 3} with diameter of 200 nm and length of several micrometers were prepared by the soft template method. The crystal structure and morphology of rods and tubes were analyzed by the X-Ray diffraction and FE-SEM. The influence of fabrication conditions and Al, Eu concentration have been discussed.

Antibacterial activity against Escherichia coli and characterization of ZnO and ZnO–Al2O3 mixed oxide nanoparticles

Directory of Open Access Journals (Sweden)

Ertan Şahin

2017-02-01

Full Text Available In order to achieve better antibacterial water insoluble nanoparticles (Nanoparticles of ZnO and ZnO–Al2O3 were studied. ZnO–Al2O3 mixed oxide nanoparticles were produced from a solution containing Zn(AC2⋅2H2O and AlCl3 by Solvothermal method. The calcination process of the ZnO–Al2O3 composite nanoparticles brought forth polycrystalline one phase ZnO–Al2O3 nanoparticles of 30–50 nm in diameters. ZnO and ZnO–Al2O3 were crystallized into würtzite and rock salt structures, respectively. The structural properties of this sample were analyzed by XRD and compared with bulk case of these samples. Antibacterial effectiveness of the ZnO and ZnO–Al2O3 nanoparticles were tested against general Escherichia coli (E. coli ATCC 25922 and E. coli O157:H7 by measuring the growth through optical density and digital counting of live–dead cells. Minimum inhibitory concentration values against four representative bacteria along with E. coli O157:H7 were also obtained.

Microstructure and optical properties of nanocrystalline ZnO and ZnO:(Li or Al) thin films

Energy Technology Data Exchange (ETDEWEB)

Oral, A. Yavuz [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze 41400 (Turkey)]. E-mail: aoral@gyte.edu.tr; Bahsi, Z. Banu [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze 41400 (Turkey); Aslan, M. Hasan [Department of Physics, Gebze Institute of Technology, Gebze 41400 (Turkey)

2007-03-15

Zinc oxide thin films (ZnO, ZnO:Li, ZnO:Al) were deposited on glass substrates by a sol-gel technique. Zinc acetate, lithium acetate, and aluminum chloride were used as metal ion sources in the precursor solutions. XRD analysis revealed that Li doped and undoped ZnO films formed single phase zincite structure in contrast to Al:ZnO films which did not fully crystallize at the annealing temperature of 550 deg. C. Crystallized films had a grain size under 50 nm and showed c-axis grain orientation. All films had a very smooth surface with RMS surface roughness values between 0.23 and 0.35 nm. Surface roughness and optical band tail values increased by Al doping. Compared to undoped ZnO films, Li doping slightly increased the optical band gap of the films.

ZnO and Al doped ZnO thin films deposited by Spray Plasma: Effect of the growth time and Al doping on microstructural, optical and electrical properties

International Nuclear Information System (INIS)

Baba, Kamal; Lazzaroni, Claudia; Nikravech, Mehrdad

2015-01-01

Nanostructured zinc oxide (ZnO) and Al doped ZnO (ZnO:Al) thin films are deposited on glass substrate by the Spray Plasma technique. Zinc nitrate and aluminium nitrate are used as Zn and Al precursors, respectively. The effect of the growth time on structural and optical properties of undoped films is studied by X-ray diffraction, atomic force microscopy, and UV–Vis spectroscopy. The effect of Al doping on microstructural, optical and electrical characteristics of ZnO:Al films is also investigated. The results show that the grain size and the film thickness both increase with the growth time. The band gap of the layers varies from 3.17 to 3.24 eV depending on the thickness. The increase of the Al doping results in the enlargement of the peak (002) and the shift of its position to higher 2θ values. Average optical transmittance decreases from 90 to 65% with the growth time because of the thickness increase while there is no significant influence of the aluminium doping on the transmittance which is above 80% in most of the visible and near-IR range for all ZnO:Al films. The electrical properties characterized by Hall measurements show that all the deposited films exhibit high resistivity, between 4 and 10 4 Ω cm. The carrier concentration decreases from 2.10 19 to 2.10 13 cm −3 when the concentration of Al increases from 1.5 to 5 atm%. - Highlights: • The original Spray Plasma technique is used for ZnO and ZnO:Al thin film deposition. • Investigation of the effect of growth time and Al doping on the structural and optical properties • Increase of grain size and film thickness with the growth time • Optical transmittance decreases from 90 to 65% with the growth time and is above 80% for ZnO:Al films in UV–Vis-NIR range. • The peak position of the (002) plane is shifted to high 2θ values with Al doping.

A facile mechanochemical approach to synthesize Zn-Al layered double hydroxide

Energy Technology Data Exchange (ETDEWEB)

Qu, Jun, E-mail: forsjun@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); He, Xiaoman; Chen, Min; Huang, Pengwu [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Zhang, Qiwu, E-mail: zhangqw@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Liu, Xinzhong [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350118 (China)

2017-06-15

In this study, a mechanochemical route to synthesize Zn-Al layered double hydroxide (LDH) was introduced, in which Zn basic carbonate and Al hydroxide were first dry milled into an activated state and then agitated in water to obtain the final products. The as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry (TG) and Scanning electron microscopy (SEM). The products possessed a high crystallinity of Zn–Al LDH phase without any other impurities, proving a facile and effective preparation of Zn–Al LDH by using non-heating mechanochemical approach. - Highlights: • A non-heating mechanochemical route to synthesize Zn-Al LDH. • The products possessed high crystalline Zn-Al LDH phase. • No emission of other impurities or wastewater.

Influence Al doped ZnO nanostructure on structural and optical properties

International Nuclear Information System (INIS)

Ramelan, Ari Handono; Wahyuningsih, Sayekti; Chasanah, Uswatul; Munawaroh, Hanik

2016-01-01

The preparation of Al-doped ZnO (AZO) thin films prepared by the spin-coating method was reported. Preparation of AZO was conducted by annealing treatment at a temperature of 700°C. While the spin-coating process of AZO thin films were done at 2000 and 3000 rpm respectively. The structural properties of ZnO were determined by X- ray diffraction (XRD) analysis. ZnOnanostructure was formed after annealed at atemperature of 400°C.The morphology of ZnO was determined by Scanning Electron Microscopy (SEM) showed the irregular morphology about 30-50µm in size. Al doped on ZnO influenced the optical properties of those material. Increasing Al contain on ZnO cause of shifting to the lower wavelength. The optical properties of the ZnO as well as AZO films showed that higher reflectance on the ultraviolet region so those materials were used as anti-reflecting agent.Al addition significantly enhance the optical transparency and induce the blue-shift in optical bandgap of ZnO films.

Fabrication of biodegradable Zn-Al-Mg alloy: Mechanical properties, corrosion behavior, cytotoxicity and antibacterial activities.

Science.gov (United States)

Bakhsheshi-Rad, H R; Hamzah, E; Low, H T; Kasiri-Asgarani, M; Farahany, S; Akbari, E; Cho, M H

2017-04-01

In this work, binary Zn-0.5Al and ternary Zn-0.5Al-xMg alloys with various Mg contents were investigated as biodegradable materials for implant applications. Compared with Zn-0.5Al (single phase), Zn-0.5Al-xMg alloys consisted of the α-Zn and Mg 2 (Zn, Al) 11 with a fine lamellar structure. The results also revealed that ternary Zn-Al-Mg alloys presented higher micro-hardness value, tensile strength and corrosion resistance compared to the binary Zn-Al alloy. In addition, the tensile strength and corrosion resistance increased with increasing the Mg content in ternary alloys. The immersion tests also indicated that the corrosion rates in the following order Zn-0.5Al-0.5MgAl-0.3MgAl-0.1MgAl. The cytotoxicity tests exhibited that the Zn-0.5Al-0.5Mg alloy presents higher viability of MC3T3-E1 cell compared to the Zn-0.5Al alloy, which suggested good biocompatibility. The antibacterial activity result of both Zn-0.5Al and Zn-0.5Al-Mg alloys against Escherichia coli presented some antibacterial activity, while the Zn-0.5Al-0.5Mg significantly prohibited the growth of Escherichia coli. Thus, Zn-0.5Al-0.5Mg alloy with appropriate mechanical properties, low corrosion rate, good biocompatibility and antibacterial activities was believed to be a good candidate as a biodegradable implant material. Copyright © 2016 Elsevier B.V. All rights reserved.

High Zn/Al ratios enhance dehydrogenation vs hydrogen transfer reactions of Zn-ZSM-5 catalytic systems in methanol conversion to aromatics

DEFF Research Database (Denmark)

Pinilla-Herrero, Irene; Borfecchia, Elisa; Holzinger, Julian

2018-01-01

suggest that catalytic activity is associated with [Zn(H2O)n(OH)]+ species located in the exchange positions of the materials with little or no contribution of ZnO or metallic Zn. The effect of Zn/Al ratio on their catalytic performance in methanol conversion to aromatics has been investigated. In all...... cases, higher Zn content causes an increase in the yield of aromatics while keeping the production of alkanes low. For similar Zn contents, high densities of Al sites favour the hydrogen transfer reactions and alkane formation whereas in samples with low Al contents, and thus higher Zn/Al ratio...

Thermomechanical Treatments on High Strength Al-Zn-Mg(-Cu) Alloys

National Research Council Canada - National Science Library

Di Russo, E; Conserva, M; Gatto, F

1974-01-01

An investigation was carried out to determine the metallurgical properties of Al-Zn-Mg and Al-Zn-Mg-Cu alloy products processed according to newly developed Final Thermomechanical Treatments (FTMT) of T-AHA type...

Pulsed laser deposited Al-doped ZnO thin films for optical applications

Directory of Open Access Journals (Sweden)

Gurpreet Kaur

2015-02-01

Full Text Available Highly transparent and conducting Al-doped ZnO (Al:ZnO thin films were grown on glass substrates using pulsed laser deposition technique. The profound effect of film thickness on the structural, optical and electrical properties of Al:ZnO thin films was observed. The X-ray diffraction depicts c-axis, plane (002 oriented thin films with hexagonal wurtzite crystal structure. Al-doping in ZnO introduces a compressive stress in the films which increase with the film thickness. AFM images reveal the columnar grain formation with low surface roughness. The versatile optical properties of Al:ZnO thin films are important for applications such as transparent electromagnetic interference (EMI shielding materials and solar cells. The obtained optical band gap (3.2–3.08 eV was found to be less than pure ZnO (3.37 eV films. The lowering in the band gap in Al:ZnO thin films could be attributed to band edge bending phenomena. The photoluminescence spectra gives sharp visible emission peaks, enables Al:ZnO thin films for light emitting devices (LEDs applications. The current–voltage (I–V measurements show the ohmic behavior of the films with resistivity (ρ~10−3 Ω cm.

Determination of Al concentration in Al doped ZnO using Auger spectra excited by Mo X-rays

International Nuclear Information System (INIS)

Toth, J.; Koever, L.; Cserny, I.; Varga, D.

2006-01-01

Complete text of publication follows. A good conductor with excellent transparency is of crucial importance for the window layer of CIGS solar cells. Al doped ZnO is a good candidate for this purpose, its conductivity depends on the concentration and chemical state of the Al dopant atoms. It was demonstrated that the non-conventional XPS using Mo X-rays for excitation is a very sensitive tool for the detection of Al, P, Si [1, 2, 3]. The present paper compares the experimental ratios for Zn/Al photoinduced peak intensity ratios obtained using both Al and Mo X-ray excitations. The Mo excited Zn/Al intensity ratios can be determined with higher selectivity and sensitivity than the Zn/Al intensity ratios excited by Al X-rays. The experiments were performed with a hemispherical deflector electron spectrometer [4]. The chemical state of the Al was identified to be close to that in Al 2 O 3 . The atomic concentrations were determined using a calibration curve based on ZnO/Al samples with known composition of Al. The energy dependent efficiency of the electron spectrometer was determined comparing REELS spectra of Cu specimen to standard spectra measured by K. Goto (Nagoya Institute of Technology, Japan). For evaluation of the Al atomic concentrations from the measured photoelectron intensities the photoionisation cross-sections of Band et al [5] and the IMFP data of S. Tanuma et al [6] and C.J. Powell and A. Jablonski [7] were used. (author)

Casting defects and mechanical properties of high pressure die cast Mg-Zn-Al-RE alloys

Energy Technology Data Exchange (ETDEWEB)

Xiao, Wenlong; Easton, Mark A.; Zhu, Suming; Nie, Jianfeng [CAST Cooperative Research Centre, Department of Materials Engineering Monash University, Melbourne, VIC (Australia); Dargusch, Matthew S. [School of Mechanical and Mining Engineering, University of Queensland, Brisbane, QLD (Australia); Gibson, Mark A. [CSIRO Process Science and Engineering, Melbourne, VIC (Australia); Jia, Shusheng [Key Laboratory of Automobile Materials, Ministry of Education, Department of Materials Science and Engineering Jilin University, Changchun (China)

2012-02-15

The die casting defects and tensile properties of high pressure die cast (HPDC) Mg-Zn-Al-RE alloys with various combinations of Zn and Al were studied. The results show that die casting defects in Mg-Zn-Al-RE alloys are affected by the percentage of Zn and Al contents. The hot tearing susceptibility (HTS) of Mg-Zn-Al-RE alloys tends to increase with increasing Zn content up to 6 wt%, while a further increase of Al and/or Zn content reduces the HTS. In tensile tests, the yield strength (YS) is generally improved by increasing Zn or Al content, whereas the tensile strength (TS) and ductility appear to depend largely on the presence of casting defects. Compared with Mg-Zn-Al alloys, the mechanical properties of the Mg-Zn-Al-RE alloy are significantly improved. The Mg-4Zn-4Al-4RE alloy is found to have few casting defects and the optimal tensile properties. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Control of interfacial intermetallic compounds in Fe–Al joining by Zn addition

Energy Technology Data Exchange (ETDEWEB)

Yang, J. [Key Laboratory of Robot and Welding Automation of Jiangxi Province, School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Center for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Li, Y.L., E-mail: liyulong1112ster@gmail.com [Key Laboratory of Robot and Welding Automation of Jiangxi Province, School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Zhang, H. [Key Laboratory of Robot and Welding Automation of Jiangxi Province, School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Guo, W. [Center for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); School of Mechanical Engineering and Automation, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Zhou, Y. [Center for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada)

2015-10-01

By Zn addition to the fusion zone, the interfacial intermetallic compounds (IMCs) of laser Al/steel joint changed from layered Fe{sub 2}Al{sub 5} and needle-like FeAl{sub 3} to layered Fe{sub 2}Al{sub 5−x}Zn{sub x} and dispersed FeZn{sub 10} with minor Al-rich amorphous phase. This resulted in an improvement in the joint strength and the change of failure mode.

Effect of ZnO nanoparticles to mechanical properties of thixoformed Mg-Al-Zn alloy

Science.gov (United States)

Kusharjanto; Soepriyanto, Syoni; Ardian Korda, Akhmad; Adi Dwiwanto, Supono

2018-03-01

Magnesium alloys are lightweight metallic materials with low mechanical properties. Therefore, in order to meet the requirements in various industrial sector applications such as automotive, aerospace and electronic frame, improvement strength and ductility is required. The purpose of this research is to investigate the effect of adding ZnO nanoparticles to changes in microstructure, hardness, mechanical properties regarding with yield and ultimate strength. In this research, the molten Mg-Al-Zn alloy is added ZnO nanoparticles with a various range of 0, 1; 3 and 5 wt% and then cooling in the room temperature. Futhermore, Mg-Al-Zn-ZnO is heated at a temperature of 530 °C (in the semi-solid temperature range 470 °C–595 °C or 53% solid fraction) and then thixoforming process is performed. The characterization results of the thixoforming product show that, the microstructure is globular in shape with maximum hardness value of 107.14 VHN, the yield strength of 214.87 MPa, and the ultimate tensile strength of 311.25 MPa in 5 wt% ZnO nanoparticles.

Performance assessment of the catalyst ZnAl2O4 and Cu/ZnAl2O4 esterification reaction fatty acid in biodiesel

International Nuclear Information System (INIS)

Feitosa, A.C.; Dantas, J.; Costa, A.C.M.F.; Barbosa, D.C.; Meneghetti, S.M.P.

2012-01-01

This study aims to evaluate the performance of the Cu/ZnAl 2 O 4 and ZnAl 2 O 4 methyl esterification of fatty acids of soybean oil into biodiesel. The ZnAl 2 O 4 was synthesized by combustion reaction and then the sample was wet impregnated with a copper source. The samples were characterized by XRD, SEM, textural analysis and catalytic tests bench. The characterization results showed that the samples showed characteristic diffraction peaks spinel, with the characteristic of mesoporous material (10-250 Å), particles in the form of blocks and slabs of hard point. The results showed that the conversion impregnation of copper has increased by 17% conversion to biodiesel. (author)

Effect of cumulative strain on texture characteristics during wire drawing of eutectoid steels

International Nuclear Information System (INIS)

Yang, F.; Ma, C.; Jiang, J.Q.; Feng, H.P.; Zhai, S.Y.

2008-01-01

The texture characteristics associated with plastic deformation of Fe-C steels near-eutectoid composition during a continuous cold drawing process were thoroughly investigated by orientation distribution function analysis based on X-ray diffraction. The effect of cumulative drawing strains on the fiber texture in drawn hypereutectoid and hypoeutectoid steel wires was discussed

Preparation and inhibition properties of molybdate intercalated ZnAlCe layered double hydroxide

Energy Technology Data Exchange (ETDEWEB)

Yan, Huajie; Wang, Jihui, E-mail: jhwang@tju.edu.cn; Zhang, Yu; Hu, Wenbin

2016-09-05

ZnAlCe layered double hydroxide intercalated by molybdate (ZnAlCe−MoO{sub 4} LDH) was successfully synthesized by using co-precipitation method, and the morphology, structure of ZnAlCe−MoO{sub 4} LDH were observed and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) techniques. The inhibition behavior of ZnAlCe−MoO{sub 4} LDH for Q235 steel in 3.5%NaCl solution was determined by polarization curves, electrochemical impedance spectroscopy (EIS), inductively coupled plasma mass spectrometer (ICP-MS) and X-ray photoelectron spectrometer (XPS) methods. The results shows that the synthesized ZnAlCe−MoO{sub 4} LDH has a lamellar structure with a particle size of 0.1–2.0 μm, an average thickness of 30 nm, and a basal plane spacing of 0.898 nm. Compared with the addition of ZnAl layered double hydroxide intercalated by nitrate (ZnAl−NO{sub 3} LDH) and ZnAl layered double hydroxide intercalated by molybdate (ZnAl−MoO{sub 4} LDH) in 3.5% NaCl solution, Q235 steel in 3.5%NaCl + ZnAlCe−MoO{sub 4} LDH solution has a lower corrosion current density, larger polarization resistance and a higher inhibition efficiency. The addition of ZnAlCe−MoO{sub 4} LDH will reduce the chloride concentration in 3.5% NaCl solution by the anion exchanged with molybdate, and improve the corrosion resistance of Q235 steel owing to the formation of passive film with the composition of ferrous or iron molybdate and deposition film with zinc and cerium hydroxides. - Highlights: • ZnAlCe−MoO{sub 4} LDH compound was successfully synthesized by co-precipitation method. • ZnAlCe−MoO{sub 4} LDH has a better inhibition effect to Q235 steel in 3.5%NaCl solution. • The Cl{sup −} ions in solution was partially exchanged with MoO{sub 4}{sup 2−} ions in host layers. • The passive film and deposition film were formed by the release of LDH compound.

The Effect of Grain-refinement on Zn-10Al Alloy Damping Properties

Directory of Open Access Journals (Sweden)

Piwowarski G.

2014-12-01

Full Text Available The paper is devoted to grain-refinement of the medium-aluminium zinc based alloys (MAl-Zn. The system examined was sand cast Zn- 10 wt. %. Al binary alloy (Zn-10Al doped with commercial Al-3 wt. % Ti - 0.15 wt. % C grain refiner (Al-3Ti-0.15C GR. Basing on the measured attenuation coefficient of ultrasonic wave it was stated that together with significantly increased structure fineness damping decreases only by about 10 - 20%. The following examinations should establish the influence of the mentioned grain-refinement on strength and ductility of MAl-Zn cast alloys.

The crystallization and physical properties of Al-doped ZnO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Chen, K.J. [Institute of Microelectronics and Department of Electrical Engineering, Center for Micro/Nano Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Fang, T.H. [Institute of Mechanical and Electromechanical Engineering, National Formosa University, Yunlin 632, Taiwan (China); Hung, F.Y. [Institute of Nanotechnology and Microsystems Engineering, Center for Micro/Nano Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)], E-mail: fyhung@mail.mse.ncku.edu.tw; Ji, L.W. [Institute of Mechanical and Electromechanical Engineering, National Formosa University, Yunlin 632, Taiwan (China); Chang, S.J.; Young, S.J. [Institute of Microelectronics and Department of Electrical Engineering, Center for Micro/Nano Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Hsiao, Y.J. [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)

2008-07-15

Un-doped Al (0-9 at.%) nanoparticles and doped ZnO powders were prepared by the sol-gel method. The nanoparticles were heated at 700-800 deg. C for 1 h in air and then analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectra and photoluminescence (PL). The results of un-doped (ZnO) and Al-doped ZnO (AZO) nanoparticles were also compared to investigate the structural characteristics and physical properties. XRD patterns of AZO powders were similar to those of ZnO powders, indicating that micro-Al ions were substituted for Zn atoms and there were no variations in the structure of the ZnO nanoparticles. From the XRD and SEM data, the grain size of the AZO nanoparticles increased from 34.41 to 40.14 nm when the annealing temperature was increased. The Raman intensity of the AZO nanoparticles (Al = 5 at.%) increased when the annealing temperature was increased. Increasing the degree of crystalline not only reduced the residual stress, but also improved the physical properties of the nanoparticles.

The crystallization and physical properties of Al-doped ZnO nanoparticles

International Nuclear Information System (INIS)

Chen, K.J.; Fang, T.H.; Hung, F.Y.; Ji, L.W.; Chang, S.J.; Young, S.J.; Hsiao, Y.J.

2008-01-01

Un-doped Al (0-9 at.%) nanoparticles and doped ZnO powders were prepared by the sol-gel method. The nanoparticles were heated at 700-800 deg. C for 1 h in air and then analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectra and photoluminescence (PL). The results of un-doped (ZnO) and Al-doped ZnO (AZO) nanoparticles were also compared to investigate the structural characteristics and physical properties. XRD patterns of AZO powders were similar to those of ZnO powders, indicating that micro-Al ions were substituted for Zn atoms and there were no variations in the structure of the ZnO nanoparticles. From the XRD and SEM data, the grain size of the AZO nanoparticles increased from 34.41 to 40.14 nm when the annealing temperature was increased. The Raman intensity of the AZO nanoparticles (Al = 5 at.%) increased when the annealing temperature was increased. Increasing the degree of crystalline not only reduced the residual stress, but also improved the physical properties of the nanoparticles

Mechanical Properties of Discontinuous Precipitated Al-Zn Alloys after Drawing at Room and Cryogenic Temperatures

Energy Technology Data Exchange (ETDEWEB)

Kim, Min Soo; Lee, Jehyun [Changwon National University, Changwon (Korea, Republic of); Han, Seung Zeon; Ahn, Jee Hyuk [Korea Institute of Materials Science, Changwon (Korea, Republic of); Lim, Sung Hwan [Kangwon National University, Chuncheon (Korea, Republic of); Kim, Kwang Ho [Pusan National University, Pusan (Korea, Republic of); Kim, Sang sik [Gyeongsang National University, Jinju (Korea, Republic of)

2017-02-15

In order to study the effect of microstructural change on the tensile properties of discontinuous precipitated Al-Zn binary alloy, four different Al-Zn alloys(25, 30, 35, 45 wt%Zn) were aged at 160 ℃ for different aging times(0, 5, 15, 30, 60, 120, 360 min) after being solution treated at 400 ℃, and successively drawn at room and cryogenic temperatures(-197 ℃). Discontinuous precipitation was formed during aging in the Al matrix(which contained more than 30 wt%Zn) in Al alloys containing more than 30 wt%Zn. The tensile strength of continuous precipitated Al-35Zn alloy decreased with increasing drawing ratio, however, the tensile strength of discontinuous precipitated Al-35Zn alloy increased with further drawing. The strength and ductility combination, 350 MPa-36%was achieved by drawning discontinuous precipitated Al-Zn alloy at room temperature. The discontinuous precipitated Al-Zn alloy drawn at cryogenic temperature showed a higher value of tensile strength, over 500 MPa, although ductility decreased.

Mechanical Properties of Discontinuous Precipitated Al-Zn Alloys after Drawing at Room and Cryogenic Temperatures

International Nuclear Information System (INIS)

Kim, Min Soo; Lee, Jehyun; Han, Seung Zeon; Ahn, Jee Hyuk; Lim, Sung Hwan; Kim, Kwang Ho; Kim, Sang sik

2017-01-01

In order to study the effect of microstructural change on the tensile properties of discontinuous precipitated Al-Zn binary alloy, four different Al-Zn alloys(25, 30, 35, 45 wt%Zn) were aged at 160 ℃ for different aging times(0, 5, 15, 30, 60, 120, 360 min) after being solution treated at 400 ℃, and successively drawn at room and cryogenic temperatures(-197 ℃). Discontinuous precipitation was formed during aging in the Al matrix(which contained more than 30 wt%Zn) in Al alloys containing more than 30 wt%Zn. The tensile strength of continuous precipitated Al-35Zn alloy decreased with increasing drawing ratio, however, the tensile strength of discontinuous precipitated Al-35Zn alloy increased with further drawing. The strength and ductility combination, 350 MPa-36%was achieved by drawning discontinuous precipitated Al-Zn alloy at room temperature. The discontinuous precipitated Al-Zn alloy drawn at cryogenic temperature showed a higher value of tensile strength, over 500 MPa, although ductility decreased.

Mechanical and wear behaviour of steel chips reinforced Zn27Al composites

Directory of Open Access Journals (Sweden)

Kenneth Kanayo ALANEME

2016-12-01

Full Text Available The mechanical and wear behaviour of Zn27Al alloy reinforced with steel machining chips (an industrial waste was investigated. Two step stir casting process was used to produce the Zn27Al based composites consisting of 5, 7.5 and 10 wt.% of the steel machining chips while unreinforced Zn27Al alloy and a composition consisting of 5 wt.% alumina were also prepared as control samples. Microstrutural analysis; mechanical and wear behaviour were assessed for these composites. The results show that the hardness and wear resistance of the composites increased with increase in weight percent of the steel chips from 5 to 10 wt.%. The UTS, strain to fracture, and the fracture toughness were however highest for the 5 wt.% steel chips reinforced composite grade; and decreased with increase in the weight percent of the steel chips from 5 to 10 wt.%. Generally the Zn27Al alloy based composites reinforced with steel machining chips, exhibited superior mechanical and wear properties in comparison to the unreinforced Zn27Al alloy and the 5 wt.% alumina reinforced Zn27Al alloy composite.

Structural, luminescence and photophysical properties of novel trimetallic nanocomposite CeO2·ZnO·ZnAl2O4

International Nuclear Information System (INIS)

Subhan, Md Abdus; Ahmed, Tanzir; Sarker, Prosenjit; Pakkanen, Tuula T.; Suvanto, Mika; Horimoto, Masahiro; Nakata, Hiroyasu

2014-01-01

A novel trimetallic nanocomposite was prepared at a temperature of around 220 °C using co-precipitation of their carbonates from aqueous solutions of the metal nitrates. The morphology of the composite was investigated with scanning electron microscopy (SEM). The X-ray, FTIR and SEM/EDS analyses data indicate that as-synthesized composite which was heated at around 220 °C exists in a nanosized form consisting of crystalline Zn 6 Al 2 (OH) 16 CO 3 ·4H 2 O and CeO 2 . Annealing at temperatures between 400 and 920 °C converts the as-synthesized composite to CeO 2 ·ZnO·ZnAl 2 O 4 multi-metal oxide consisting of crystalline CeO 2 , ZnO and semicrystalline ZnAl 2 O 4 . Photoluminescence (PL) spectra of the as-synthesized sample showed emissions at 440 and 590 nm. PL spectra of CeO 2 ·ZnO·ZnAl 2 O 4 annealed at 920 °C was recorded and three sharp lines were observed at 627 nm (1.98 eV), 530 nm (2.34 eV) and 465 nm (2.67 eV) with broad peaks at 540 nm (2.3 eV) and 400 nm (3.1 eV). These sharp lines resemble to those of CeO 2 and the broad peaks originate from ZnO. The indirect band gap of the as-synthesized composite was found to be 2.44 eV. The luminescence lifetime at 4 K was measured to be 38 μs. -- Highlights: • A novel trimetallic nanocomposite, CeO 2 ·ZnO·ZnAl 2 O 4 has been synthesized and characterized. • At around 220 °C as-synthesized samples exist in crystalline Zn 6 Al 2 (OH) 16 CO 3 ·4H 2 O and CeO 2 . • Annealing at temperatures between 400 and 920 °C converts the composite to CeO 2 ·ZnO·ZnAl 2 O 4 . • The luminescence lifetime of the composite at 4 K was measured to be 38 μs. • PL of CeO 2 ·ZnO·ZnAl 2 O 4 shows three sharp peaks at 627 nm, 530 nm and 465 nm

Low Temperature Mechanical Properties of Scandium-Modified Al-Zn-Mg-Cu Alloys

National Research Council Canada - National Science Library

Senkov, O

2002-01-01

Tensile properties of three wrought alloys, (1) Al-10Zn-3Mg-1.2Cu-0.15Zr, (2) Al-10Zn-3Mg-1.2Cu-0.15Zr-0.39Mn-0.49Sc, and (3) Al-12Zn-3Mg-1.2Cu-0.15Zr-0.39Mn-0.49Sc were studied in T6 and T7 conditions at 298K and 77K...

Structural, optical, and LED characteristics of ZnO and Al doped ZnO thin films

Science.gov (United States)

Sandeep, K. M.; Bhat, Shreesha; Dharmaprakash, S. M.

2017-05-01

ZnO (pristine) and Al doped ZnO (AZO) films were prepared using sol-gel spin coating method. The XRD analysis showed the enhanced compressive stress in AZO film. The presence of extended states below the conduction band edge in AZO accounts for the redshift in optical bandgap. The PL spectra of AZO showed significant blue emission due to the carrier recombination from defect states. The TRPL curves showed the dominant DAP recombination in ZnO film, whereas defect related recombination in Al doped ZnO film. Color parameters viz: the dominant wavelength, color coordinates (x,y), color purity, luminous efficiency and correlated color temperature (CCT) of ZnO and AZO films are calculated using 1931 (CIE) diagram. Further, a strong blue emission with color purity more than 96% is observed in both the films. The enhanced blue emission in AZO significantly increased the luminous efficiency (22.8%) compared to ZnO film (10.8%). The prepared films may be used as blue phosphors in white light generation.

Al-doped ZnO nanofilms: Synthesis and characterization

Energy Technology Data Exchange (ETDEWEB)

Huczko, A.; Dabrowska, A. [Department of Chemistry, Warsaw University, Warsaw (Poland); Madhup, D.K. [Department of Physics, Kathmandu University, Dhulikhel (Nepal); College of Biomedical Engineering and Applied Sciences, Hadigaun, Kathmandu (Nepal); Subedi, D.P.; Chimouriya, S.P. [Department of Physics, Kathmandu University, Dhulikhel (Nepal)

2010-12-15

Al-doped and un-doped ZnO nanofilms on quartz substrate were obtained by ultrasonic spray pyrolysis of salt solutions (mole concentration of Al within 0-10%). The films were characterized by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Atomic force microscopy (AFM) and UV spectroscopy to study the morphology and optical properties. The optical studies showed that the increase in Al within ZnO thin layer increases its band gap energy. The obtained value of band gap energy is very close to the determined oscillation energy. However, the dispersion energy is nearly half of band gap energy value. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Dependences of the Al thickness and annealing temperature on the structural, optical and electrical properties in ZnO/Al multilayers

International Nuclear Information System (INIS)

Hu, Y.M.; Lin, C.W.; Huang, J.C.A.

2006-01-01

High-quality (0001) oriented ZnO (300 A) film and [ZnO(100 A)/Al(t Al )] 3 (t Al = 0.6, 1.7, 2.8 A) multilayers have been established at room temperature on Al 2 O 3 (0001) substrates by ion-beam sputtering. The structural, optical and electrical properties of multilayers as functions of both the Al thickness and annealing temperature are reported. We have verified that Al thickness and annealing temperature are the key factors to optimize transparency-conducting property in ZnO/Al multilayers. The optimum Al thickness and annealing temperature for ZnO/Al multilayer of 300 A thin is 1.7 A (about one Al atomic layer) and 400 deg. C, respectively, leading to the relatively lower resistivity (2.8 x 10 -3 Ω cm) and higher Hall mobility (10 cm 2 /V.s) without suppression of the visible transmittance (above 85%)

Synthesis and structural transformations of hydrotalcite-like materials Mg-Al and Zn-Al

NARCIS (Netherlands)

Prihod'ko, R.V.; Sychev, M.V.; Astrelin, I.M.; Erdmann, K.; Mangel, A.; Santen, van R.A.

2001-01-01

Mg-Al and Zn-Al hydrotalcite-like layered double hydroxides of various compositions were synthesized and characterized. A detailed comparative analysis of the structure and composition of starting and reconstructed layered double hydroxides was made

Intercalation of diclofenac in modified Zn/Al hydrotalcite-like preparation

Science.gov (United States)

Heraldy, E.; Suprihatin, R. W.; Pranoto

2016-02-01

The intercalation of a pharmaceutically active material diclofenac into modified Zn/Al Hydrotalcite-like (Zn/Al HTlc) preparation has been investigated by the coprecipitation and ion exchange method, respectively. The synthetic materials were characterized using X- Ray Diffraction (XRD); Fourier transforms infrared spectroscopy (FTIR); Scanning Electron Microscope (SEM); X-Ray Fluorescence (XRF) and surface area analyzer. The results show that the basal spacing of the product was expanded to 11.03 A for direct synthesis and 10.68 A for indirect synthesis, suggesting that diclofenac anion was intercalated into Zn/Al HTlc and arranged in a tilted bilayer fashion and the specific surface area of material increased after the intercalation of diclofenac.

Detecting the Extent of Cellular Decomposition after Sub-Eutectoid Annealing in Rolled UMo Foils

Energy Technology Data Exchange (ETDEWEB)

Kautz, Elizabeth J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jana, Saumyadeep [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Devaraj, Arun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sweet, Lucas E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2017-07-31

This report presents an automated image processing approach to quantifying microstructure image data, specifically the extent of eutectoid (cellular) decomposition in rolled U-10Mo foils. An image processing approach is used here to be able to quantitatively describe microstructure image data in order to relate microstructure to processing parameters (time, temperature, deformation).

Corrosion prevention of the rail by thermal spray coating of Zn-Al alloy; Zn-Al gokin yosha hifuku ni yoru reru no boshoku

Energy Technology Data Exchange (ETDEWEB)

Mizoguchi, S. [Nippon Steel Corp., Kitakyushu (Japan)] Urashima, C. [Kyushu Techno Research Corp., Fukuoka (Japan); Itai, K. [Nippon Steel Corp., Kitakyushu, Fukuoka (Japan). Technical Research Inst. of Yawata Works; Ichiriki, T.; Nishiki, M. [Kyushu Rail way comdany, Fukuoka (Japan)

1997-03-30

Replacement of the rail in under-sea tunnel such as the Kammon Tunnel is carried out very five years because of the severe corrosion caused by the humid state due to the leakage of sea water or the mist of sea water swept up by the passing trains. In this study, salt water spraying or sea water spraying test is carried out using Zn-Al alloy with the corrosion resistance and thermal spray efficiency even higher than those of Zn or Al. A rail coated by thermal spray of Zn-15mass%Al alloy has been laid by trial in the practical rail road of Kammon Tunnel for 5 years and 3 months, the deterioration degree of the coating, pitting depth, actual fatigue strength, etc. are evaluated. Further, these factors of a rail re-coated by Zincrich Primer+Tar Epoxy and a bare rail laid at the same time are evaluated for comparison. It is presumed by the results of the examination about the service life of a rail coated by the thermal spray of Zn-Al alloy based on the pitting depth in the rail base that the service life of such coated rail is more than twice as that of the bare rails used currently. 5 refs., 14 figs., 3 tabs.

First-principle Calculations of Mechanical Properties of Al2Cu, Al2CuMg and MgZn2 Intermetallics in High Strength Aluminum Alloys

Directory of Open Access Journals (Sweden)

LIAO Fei

2016-12-01

Full Text Available Structural stabilities, mechanical properties and electronic structures of Al2Cu, Al2CuMg and MgZn2 intermetallics in Al-Zn-Mg-Cu aluminum alloys were determined from the first-principle calculations by VASP based on the density functional theory. The results show that the cohesive energy (Ecoh decreases in the order MgZn2 > Al2CuMg > Al2Cu, whereas the formation enthalpy (ΔH decreases in the order MgZn2 > Al2Cu > Al2CuMg. Al2Cu can act as a strengthening phase for its ductile and high Young's modulus. The Al2CuMg phase exhibits elastic anisotropy and may act as a crack initiation point. MgZn2 has good plasticity and low melting point, which is the main strengthening phase in the Al-Zn-Mg-Cu aluminum alloys. Metallic bonding mode coexists with a fractional ionic interaction in Al2Cu, Al2CuMg and MgZn2, and that improves the structural stability. In order to improve the alloys' performance further, the generation of MgZn2 phase should be promoted by increasing Zn content while Mg and Cu contents are decreased properly.

Magnetism and magnetoresistance from different origins in Co/ZnO:Al granular films

Energy Technology Data Exchange (ETDEWEB)

Quan, Zhiyong, E-mail: quanzy@sxnu.edu.cn; Liu, Xia; Song, Zhilin; Xu, Xiaohong, E-mail: xuxh@dns.sxnu.edu.cn

2016-12-01

Co/ZnO:Al granular films were made on glass substrates by sequential magnetron sputter deposition of ultrathin Co layer and ZnO:Al layer at room temperature. The as-deposited films consist of superparamagnetic Co particles dispersed in ZnO:Al (~2% Al) semiconductor matrix. Distinguished magnetoresistance effect at room temperature was obtained in the as-deposited films, which obviously reduced after annealing due to the growth of Co particles. The size of important magnetic particles was analyzed by Langevin function for hysteresis loops and magnetoresistance curves at room temperature. It was found that small magnetic particle contribute to magnetoresistance behavior and large particles dominate the room temperature magnetism in Co/ZnO:Al granular films.

Al-Doped ZnO Monolayer as a Promising Transparent Electrode Material: A First-Principles Study

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Mingyang Wu

2017-03-01

Full Text Available Al-doped ZnO has attracted much attention as a transparent electrode. The graphene-like ZnO monolayer as a two-dimensional nanostructure material shows exceptional properties compared to bulk ZnO. Here, through first-principle calculations, we found that the transparency in the visible light region of Al-doped ZnO monolayer is significantly enhanced compared to the bulk counterpart. In particular, the 12.5 at% Al-doped ZnO monolayer exhibits the highest visible transmittance of above 99%. Further, the electrical conductivity of the ZnO monolayer is enhanced as a result of Al doping, which also occurred in the bulk system. Our results suggest that Al-doped ZnO monolayer is a promising transparent conducting electrode for nanoscale optoelectronic device applications.

A Comparative Study of Carbon Nanotubes Synthesized from Co/Zn/Al and Fe/Ni/Al Catalyst

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Ezekiel Dixon Dikio

2011-01-01

Full Text Available The catalyst systems Fe/Ni/Al and Co/Zn/Al were synthesized and used in the synthesis of carbon nanotubes. The carbon nanotubes produced were characterized by Field Emission Scanning Electron Microscope (FE-SEM, Energy Dispersive x-ray Spectroscopy (EDS, Raman spectroscopy, Thermogravimetric Analysis (TGA and Transmission Electron Microscope (TEM. A comparison of the morphological profile of the carbon nanotubes produced from these catalysts indicates the catalyst system Fe/Ni/Al to have produced higher quality carbon nanotubes than the catalyst system Co/Zn/Al.

Plasmonic enhancement of UV emission from ZnO thin films induced by Al nano-concave arrays

International Nuclear Information System (INIS)

Norek, Małgorzata; Łuka, Grzegorz; Włodarski, Maksymilian

2016-01-01

Highlights: • Al nano-concave arrays with different interpore distance (D c ) were prepared. • PL of ZnO thin films deposited directly on the Al nano-concaves were studied. • The effect of 10 nm Al 2 O 3 spacer on PL emission from ZnO thin films was analyzed. • Plasmonic enhancement of the PL emission was dependent on the D c and the spacer. • The highest 9-fold enhancement was obtained for the Al/ZnO sample with D c ∼333 nm. - Abstract: Surface plasmons (SPs) supported by Al nano-concave arrays with increasing interpore distance (D c ) were used to enhance the ultraviolet light emission from ZnO thin films. Two sets of samples were prepared: in the first set the thin ZnO films were deposited directly on Al nanoconcaves (the Al/ZnO samples) and in the second set a 10 nm − Al 2 O 3 spacer was placed between the textured Al and the ZnO films (the Al/Al 2 O 3 -ALD/ZnO samples). In the Al/ZnO samples the enhancement was limited by a nonradiative energy dissipation due to the Ohmic loss in the Al metal. However, for the ZnO layer deposited directly on Al nanopits synthesized at 150 V (D c = 333 ± 18 nm), the largest 9-fold enhancement was obtained by achieving the best energy fit between the near band-edge (NBE) emission from ZnO and the λ (0,1) SPP resonance mode. In the Al/Al 2 O 3 -ALD/ZnO samples the amplification of the UV emission was smaller than in the Al/ZnO samples due to a big energy mismatch between the NBE emission and the λ (0,1) plasmonic mode. The results obtained in this work indicate that better tuning of the NBE − λ (0,1) SPP resonance mode coupling is possible through a proper modification of geometrical parameters in the Al/Al 2 O 3 -ALD/ZnO system such as Al nano-concave spacing and the thickness of the corresponding layer. This approach will reduce the negative influence of the non-radiative plasmonic modes and most likely will lead to further enhancement of the SP-modulated UV emission from ZnO thin films.

Plasmonic enhancement of UV emission from ZnO thin films induced by Al nano-concave arrays

Energy Technology Data Exchange (ETDEWEB)

Norek, Małgorzata, E-mail: mnorek@wat.edu.pl [Department of Advanced Materials and Technologies, Faculty of Advanced Technologies and Chemistry, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); Łuka, Grzegorz [Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw (Poland); Włodarski, Maksymilian [Institute of Optoelectronics, Military University of Technology, Str. Kaliskiego 2, 00-908 Warszawa (Poland)

2016-10-30

Highlights: • Al nano-concave arrays with different interpore distance (D{sub c}) were prepared. • PL of ZnO thin films deposited directly on the Al nano-concaves were studied. • The effect of 10 nm Al{sub 2}O{sub 3} spacer on PL emission from ZnO thin films was analyzed. • Plasmonic enhancement of the PL emission was dependent on the D{sub c} and the spacer. • The highest 9-fold enhancement was obtained for the Al/ZnO sample with D{sub c} ∼333 nm. - Abstract: Surface plasmons (SPs) supported by Al nano-concave arrays with increasing interpore distance (D{sub c}) were used to enhance the ultraviolet light emission from ZnO thin films. Two sets of samples were prepared: in the first set the thin ZnO films were deposited directly on Al nanoconcaves (the Al/ZnO samples) and in the second set a 10 nm − Al{sub 2}O{sub 3} spacer was placed between the textured Al and the ZnO films (the Al/Al{sub 2}O{sub 3}-ALD/ZnO samples). In the Al/ZnO samples the enhancement was limited by a nonradiative energy dissipation due to the Ohmic loss in the Al metal. However, for the ZnO layer deposited directly on Al nanopits synthesized at 150 V (D{sub c} = 333 ± 18 nm), the largest 9-fold enhancement was obtained by achieving the best energy fit between the near band-edge (NBE) emission from ZnO and the λ{sub (0,1)} SPP resonance mode. In the Al/Al{sub 2}O{sub 3}-ALD/ZnO samples the amplification of the UV emission was smaller than in the Al/ZnO samples due to a big energy mismatch between the NBE emission and the λ{sub (0,1)} plasmonic mode. The results obtained in this work indicate that better tuning of the NBE − λ{sub (0,1)} SPP resonance mode coupling is possible through a proper modification of geometrical parameters in the Al/Al{sub 2}O{sub 3}-ALD/ZnO system such as Al nano-concave spacing and the thickness of the corresponding layer. This approach will reduce the negative influence of the non-radiative plasmonic modes and most likely will lead to further

Degradability Enhancement of Poly(Lactic Acid) by Stearate-Zn3Al LDH Nanolayers

Science.gov (United States)

Eili, Mahboobeh; Shameli, Kamyar; Ibrahim, Nor Azowa; Yunus, Wan Md Zin Wan

2012-01-01

Recent environmental problems and societal concerns associated with the disposal of petroleum based plastics throughout the world have triggered renewed efforts to develop new biodegradable products compatible with our environment. This article describes the preparation, characterization and biodegradation study of poly(lactic acid)/layered double hydroxide (PLA/LDH) nanocomposites from PLA and stearate-Zn3Al LDH. A solution casting method was used to prepare PLA/stearate-Zn3Al LDH nanocomposites. The anionic clay Zn3Al LDH was firstly prepared by co-precipitation method from a nitrate salt solution at pH 7.0 and then modified by stearate anions through an ion exchange reaction. This modification increased the basal spacing of the synthetic clay from 8.83 Å to 40.10 Å. The morphology and properties of the prepared PLA/stearate-Zn3Al LDH nanocomposites were studied by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), thermogravimetric analysis (TGA), tensile tests as well as biodegradation studies. From the XRD analysis and TEM observation, the stearate-Zn3Al LDH lost its ordered stacking-structure and was greatly exfoliated in the PLA matrix. Tensile test results of PLA/stearate-Zn3Al LDH nanocomposites showed that the presence of around 1.0–3.0 wt % of the stearate-Zn3Al LDH in the PLA drastically improved its elongation at break. The biodegradation studies demonstrated a significant biodegradation rate improvement of PLA in the presence of stearate-Zn3Al LDH nanolayers. This effect can be caused by the catalytic role of the stearate groups in the biodegradation mechanism leading to much faster disintegration of nanocomposites than pure PLA. PMID:22942682

Preparation and characterization of chitosan/ZnAl2O4 films

International Nuclear Information System (INIS)

Araujo, P.M.A.G.; Santos, P.T.A.; Rodrigues, P.A.; Costa, A.C.F.M.; Araujo, E.M.

2012-01-01

Chitosan films have been explored for biomedical application, as the chitosan to be, low toxicity, abundant in nature, show affinity for dispersion loads and high mechanical strength. On the other hand, ZnAl 2 O 4 has energy gap of approximately 3.8 eV, which makes it useful for use as photoelectric device ultraviolet. Thus, this work has as objective to prepare films of quitosana/ZnAl 2 O 4 in proportions of 5:1, 5:2, 5:3, 5:4 and evaluate the structural, morphological and thermals characteristics. To this end, ZnAl2O4 first nanoparticles (NPs) was deagglomerated and 325 mesh sieve and added to chitosan diluted in 1% acetic acid, and dried at 60°C. After drying, a solution of 1M sodium hydroxide was added to obtain a film with neutral pH. The films were characterized by XRD, SEM and TG. For all proportions evaluated it was verified the presence of ZnAl 2 O)4 and chitosan phases. By micrographs, it was observed that there was formation of agglomerates of ZnAl 2 O 4 NPs both on the surface of the films, the encapsulated in chitosan. In all samples the ratio 5:4 showed the greatest consistency both in relation to the film surface of the nanoparticles in the chitosan matrix. TG/DTA curves of quitosana/ZnAl 2 O 4 film for all the samples showed that for the concentration of 5:1 to 5:3 occurred three mass loss while for concentration of 5:2 to 5:4 were only two stages decomposition. (author)

Microstructural characteristics and aging response of Zn-containing Al-Mg-Si-Cu alloy

Science.gov (United States)

Cai, Yuan-hua; Wang, Cong; Zhang, Ji-shan

2013-07-01

Al-Mg-Si-Cu alloys with and without Zn addition were fabricated by conventional ingot metallurgy method. The microstructures and properties were investigated using optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), tensile test, hardness test, and electrical conductivity measurement. It is found that the as-cast Al-Mg-Si-Cu-Zn alloy is composed of coarse dendritic grains, long needle-like β/δ-AlFeSi white intermetallics, and Chinese script-like α-AlFeSi compounds. During high temperature homogenization treatment, only harmful needle-like β-AlFeSi phase undergoes fragmentation and spheroidizing at its tips, and the destructive needle-like δ-phase does not show any morphological and size changes. Phase transitions from β-AlFeSi to α-AlFeSi and from δ-AlFeSi to β-AlFeSi are also not found. Zn addition improves the aging hardening response during the former aging stage and postpones the peak-aged hardness to a long aging time. In T4 condition, Zn addition does not obviously increase the yield strength and decrease the elongation, but it markedly improves paint-bake hardening response during paint-bake cycle. The addition of 0.5wt% Zn can lead to an increment of 99 MPa in yield strength compared with the value of 69 MPa for the alloy without Zn after paint-bake cycle.

Ultrasonic spray pyrolysis growth of ZnO and ZnO:Al nanostructured films: Application to photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Kenanakis, G., E-mail: gkenanak@iesl.forth.gr [Institute of Electronic Structure and Laser, Foundation for Research and Technology – Hellas, P.O. Box 1385, Vassilika Vouton, 711 10 Heraklion, Crete (Greece); Center of Materials Technology and Photonics, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Katsarakis, N. [Institute of Electronic Structure and Laser, Foundation for Research and Technology – Hellas, P.O. Box 1385, Vassilika Vouton, 711 10 Heraklion, Crete (Greece); Center of Materials Technology and Photonics, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece)

2014-12-15

Highlights: • Al–ZnO thin films and nanostructures were obtained by ultrasonic spray pyrolysis. • The texture and morphology of the samples depend on the deposition parameters. • The photocatalytic degradation of stearic acid was studied upon UV-A irradiation. - Abstract: Pure and Al-doped ZnO (Al = 1, 3, 5%) nanostructured thin films were grown at 400 °C on glass substrates by ultrasonic spray pyrolysis, a simple, environmental-friendly and inexpensive method, using aqueous solutions as precursors. The structural and morphological characteristics of the samples depend drastically on deposition parameters; ZnO nanostructured films, nanopetals and nanorods were systematically obtained by simply varying the precursor solution and/or the spraying time. Transmittance measurements have shown that all samples are transparent in the visible wavelength region. Finally, the photocatalytic properties of the samples were investigated against the degradation of stearic acid under UV-A light illumination (365 nm); both pure and Al-doped ZnO nanostructured thin films show good photocatalytic activity regarding the degradation of stearic acid, due to their good crystallinity and large surface area.

Al-doped ZnO mechanical milled powders for dye sensitized cells

International Nuclear Information System (INIS)

Damonte, L.C.; Donderis, V.; Ferrari, S.; Orozco, J.; Hernandez-Fenollosa, M.A.

2010-01-01

Mixtures of Al 2 O 3 and ZnO powders were prepared by mechanical milling. The resulting samples were analyzed and characterized by X-ray diffraction (XRD), positron annihilation lifetime spectroscopy (PALS), scanning electron microscopy (SEM) and optical reflection spectroscopy (OPS). XRD and PALS measurements confirm Al incorporation into ZnO wurtzite structure. Powders obtained from Al 2 O 3 precursors display better reflectivity than those prepared from Al metal so they might be better materials for implementation in photovoltaic solar devices.

Amplified spontaneous emission from ZnO in n-ZnO/ZnO nanodots-SiO(2) composite/p-AlGaN heterojunction light-emitting diodes.

Science.gov (United States)

Shih, Ying Tsang; Wu, Mong Kai; Li, Wei Chih; Kuan, Hon; Yang, Jer Ren; Shiojiri, Makoto; Chen, Miin Jang

2009-04-22

This study demonstrates amplified spontaneous emission (ASE) of the ultraviolet (UV) electroluminescence (EL) from ZnO at lambda~380 nm in the n-ZnO/ZnO nanodots-SiO(2) composite/p- Al(0.12)Ga(0.88)N heterojunction light-emitting diode. A SiO(2) layer embedded with ZnO nanodots was prepared on the p-type Al(0.12)Ga(0.88)N using spin-on coating of SiO(2) nanoparticles followed by atomic layer deposition (ALD) of ZnO. An n-type Al-doped ZnO layer was deposited upon the ZnO nanodots-SiO(2) composite layer also by the ALD technique. High-resolution transmission electron microscopy (HRTEM) reveals that the ZnO nanodots embedded in the SiO(2) matrix have diameters of 3-8 nm and the wurtzite crystal structure, which allows the transport of carriers through the thick ZnO nanodots-SiO(2) composite layer. The high quality of the n-ZnO layer was manifested by the well crystallized lattice image in the HRTEM picture and the low-threshold optically pumped stimulated emission. The low refractive index of the ZnO nanodots-SiO(2) composite layer results in the increase in the light extraction efficiency from n-ZnO and the internal optical feedback of UV EL into n-ZnO layer. Consequently, significant enhancement of the UV EL intensity and super-linear increase in the EL intensity, as well as the spectral narrowing, with injection current were observed owing to ASE in the n-ZnO layer.

Air permeability of the artificially synthesized Zn-Al-Mg alloy rusts

International Nuclear Information System (INIS)

Ishikawa, Tatsuo; Ueda, Masato; Kandori, Kazuhiko; Nakayama, Takenori

2007-01-01

The rust particles of Zn-Al-Mg alloys were synthesized from aqueous solutions dissolving ZnCl 2 , AlCl 3 , and MgCl 2 at different atomic ratios of the metal ions. The crystal phase and particle morphology of the products depended on the composition of the starting solutions. The compactness of the layers of the products was estimated by measuring their air permeability. The layer of mixed metal hydroxide chloride formed at Zn:Al:Mg = 1:1:1 showed a highest compactness, that was ascribed to the preferred orientation of the fine plate particles. The addition of Mg(II) made plate particles smaller to give more compact layers

Hydrodeoxygenation of furfuryl alcohol over Cu/MgAl and Cu/ZnAl catalysts derived from hydrotalcite-like precursors

Directory of Open Access Journals (Sweden)

Natalia Andrea Pino

2017-01-01

Full Text Available The aqueous phase hydrodeoxygenation (HDO of furfuryl alcohol over Cu/MgAl and Cu/ZnAl catalysts with different Mg/Al and Zn/Al molar ratios, were investigated. Mg-Al and Zn-Al mixed oxides derived from hydrotalcites precursors were used as supports, which were impregnated with an aqueous solution of copper nitrate by incipient wetness impregnation. The HDO reaction was carried out in a typical batch reactor at 5 MPa of H2 and 200 °C for 4 h. Among the catalysts studied, the Cu/MgAl-0.5 catalyst exhibited the higher furfuryl alcohol conversion (86% and yield of cyclopentanol (35%, which is the reaction product with the highest hydrogen-carbon (H/C ratio. With the Cu/MgAl-3 catalyst a high cyclopentanone yield (67% was achieved. The results obtained, showed that copper supported on mixed oxides catalysts derived from hydrotalcite precursors are a promising alternative to improve the bio-oil quality.

Performance assessment of the catalyst ZnAl{sub 2}O{sub 4} and Cu/ZnAl{sub 2}O{sub 4} esterification reaction fatty acid in biodiesel; Avaliacao do desempenho do catalisador ZnAl{sub 2}O{sub 4} e Cu/ZnAl{sub 2}O{sub 4} na reacao de estereficacao de acidos graxos em biodiesel

Energy Technology Data Exchange (ETDEWEB)

Feitosa, A.C.; Dantas, J.; Costa, A.C.M.F., E-mail: alexcaval2@hotmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Departamento de Engenharia de Materiais; Barbosa, D.C.; Meneghetti, S.M.P. [Universidade Federal de Alagoas (UFAL), Maceio, AL (Brazil). Dept. de Quimica

2012-07-01

This study aims to evaluate the performance of the Cu/ZnAl{sub 2}O{sub 4} and ZnAl{sub 2}O{sub 4} methyl esterification of fatty acids of soybean oil into biodiesel. The ZnAl{sub 2}O{sub 4} was synthesized by combustion reaction and then the sample was wet impregnated with a copper source. The samples were characterized by XRD, SEM, textural analysis and catalytic tests bench. The characterization results showed that the samples showed characteristic diffraction peaks spinel, with the characteristic of mesoporous material (10-250 Å), particles in the form of blocks and slabs of hard point. The results showed that the conversion impregnation of copper has increased by 17% conversion to biodiesel. (author)

The Influence of α- and γ-Al2O3 Phases on the Thermoelectric Properties of Al-doped ZnO

DEFF Research Database (Denmark)

Han, Li; Van Nong, Ngo; Le, Thanh Hung

2013-01-01

A systematic investigation on the microstructure and thermoelectric properties of Al-doped ZnO using α- and γ-Al2O3 as dopants was conducted in order to understand the doping effect and its mechanism. The samples were prepared by the spark plasma sintering technique from precursors calcined...... at various temperatures. Clear differences in microstructure and thermoelectric properties were observed between the samples doped with α- and γ-Al2O3. At any given calcination temperature, γ-Al2O3 resulted in the formation of a larger amount of the ZnAl2O4 phase in the Al-doped ZnO samples. The average...... grain size was found to be smaller for the γ-Al2O3-doped samples than that for the α-Al2O3-doped ones under the same sintering condition. It is proposed that the ZnAl2O4 phase is the reason for the observed suppression of grain growth and also for the slightly reduced lattice thermal conductivity...

Al-doped ZnO mechanical milled powders for dye sensitized cells

Energy Technology Data Exchange (ETDEWEB)

Damonte, L.C., E-mail: damonte@fisica.unlp.edu.a [Departamento de Fisica, UNLP, IFLP-CCT-CONICET, C.C.67(1900), La Plata (Argentina); Dto. de Fisica Aplicada, Universidad Politecnica de Valencia, Cami de Vera s/n, 46022 Valencia (Spain); Donderis, V. [Dto. de Ingenieria Electrica, Universidad Politecnica de Valencia, Cami de Vera s/n, 46022 Valencia (Spain); Ferrari, S. [Departamento de Fisica, UNLP, IFLP-CCT-CONICET, C.C.67(1900), La Plata (Argentina); Orozco, J. [ITM, Universidad Politecnica de Valencia, Cami de Vera s/n, 46022 Valencia (Spain); Hernandez-Fenollosa, M.A. [Dto. de Fisica Aplicada, Universidad Politecnica de Valencia, Cami de Vera s/n, 46022 Valencia (Spain)

2010-04-16

Mixtures of Al{sub 2}O{sub 3} and ZnO powders were prepared by mechanical milling. The resulting samples were analyzed and characterized by X-ray diffraction (XRD), positron annihilation lifetime spectroscopy (PALS), scanning electron microscopy (SEM) and optical reflection spectroscopy (OPS). XRD and PALS measurements confirm Al incorporation into ZnO wurtzite structure. Powders obtained from Al{sub 2}O{sub 3} precursors display better reflectivity than those prepared from Al metal so they might be better materials for implementation in photovoltaic solar devices.

DC-magnetron sputtering of ZnO:Al films on (00.1)Al2O3 substrates from slip-casting sintered ceramic targets

International Nuclear Information System (INIS)

Miccoli, I.; Spampinato, R.; Marzo, F.; Prete, P.; Lovergine, N.

2014-01-01

Highlights: • ZnO:Al was DC-sputtered on sapphire >350 °C by slip-casting sintered AZO target. • Films are highly (00.1)-oriented, smooth and transparent in the NIR–visible range. • Films growth rate decreases with temperature, while their grain size increases. • A high temperature reduction for sticking coefficients of impinging species is proved. • We prove that Thornton model does not apply to high-temperature DC-sputtered ZnO. - Abstract: High (>350 °C) temperature DC-sputtering deposition of ZnO:Al thin films onto single-crystal (00.1) oriented Al 2 O 3 (sapphire) substrates is reported, using a ultrahigh-density, low-resistivity and low-cost composite ceramic target produced by slip-casting (pressureless) sintering of ZnO–Al 2 O 3 (AZO) powders. The original combination of high-angle θ–2θ (Bragg–Brentano geometry) X-ray diffraction with low angle θ–2θ X-ray reflectivity (XRR) techniques allows us to define the AZO target composition and investigate the structural properties and surface/interface roughness of as-sputtered ZnO:Al films; besides, the growth dynamics of ZnO:Al is unambiguously determined. The target turned out composed of the sole wurtzite ZnO and spinel ZnAl 2 O 4 phases. X-ray diffraction analyses revealed highly (00.1)-oriented (epitaxial) ZnO:Al films, the material mean crystallite size being in the 13–20 nm range and increasing with temperature between 350 °C and 450 °C, while the film growth rate (determined via XRR measurements) decreases appreciably. XRR spectra also allowed to determine rms surface roughness <1 nm for present films and showed ZnO:Al density changes by only a few percent between 350 °C and 450 °C. The latter result disproves the often-adopted Thornton model for the description of the sputter-grown ZnO films and instead points out toward a reduction of the sticking coefficients of impinging species, as the main origin of film growth rate and grain size dependence with temperature. ZnO:Al

Functional Performances of CuZnAl Shape Memory Alloy Open-Cell Foams

Science.gov (United States)

Biffi, C. A.; Casati, R.; Bassani, P.; Tuissi, A.

2018-01-01

Shape memory alloys (SMAs) with cellular structure offer a unique mixture of thermo-physical-mechanical properties. These characteristics can be tuned by changing the pore size and make the shape memory metallic foams very attractive for developing new devices for structural and functional applications. In this work, CuZnAl SMA foams were produced through the liquid infiltration of space holder method. In comparison, a conventional CuZn brass alloy was foamed trough the same method. Functional performances were studied on both bulk and foamed SMA specimens. Calorimetric response shows similar martensitic transformation (MT) below 0 °C. Compressive response of CuZnAl revealed that mechanical behavior is strongly affected by sample morphology and that damping capacity of metallic foam is increased above the MT temperatures. The shape memory effect was detected in the CuZnAl foams. The conventional brass shows a compressive response similar to that of the martensitic CuZnAl, in which plastic deformation accumulation occurs up to the cellular structure densification after few thermal cycles.

Effect of impurities on microstructure and structural propertiesof the as-cast and treated Al-Zn alloys

Directory of Open Access Journals (Sweden)

Douniazed Lamrous

2014-03-01

Full Text Available The microstructure of two Al-Zn alloys (with 10 and 30 wt.%Zn content produced by melting in the high frequency induction furnace were investigated by means of scanning electron microscopy (SEM, energy dispersive X-ray (EDX spectroscopy, X-ray diffraction (XRD analysis and the microhardness tests. The results indicate that the presence of iron impurity causes the formation of eutectic (Al,Zn3Fe in both alloys. The presence of the silicon impurity results in the formation of the phase separation in the Al-10%Zn as-cast alloy. The columnar to equiaxed transition was produced only in the Al-30%Zn as-cast alloy. The Vickers microhardness is higher in the equiaxed zone than in the columnar to equiaxed transition (CET zone. The presence of iron causes intermetallic phase formation (Al, Fe, Si3,6Zn in the Al-30%Zn as-cast alloy enabling an increase in the lattice parameter. After a homogenization treatment, the microstructure of Al-Zn treated alloys consists only of α dendrites and stable eutectic phase.

Effect of ageing time 200 °C on microstructure behaviour of Al-Zn-Cu-Mg cast alloys

Directory of Open Access Journals (Sweden)

Pratiwi Diah Kusuma

2017-01-01

Full Text Available Al-Zn-Cu-Mg is heat treatable alloy that can be used in many hightech applications, such as aerospace and military. The main objective of this study is to investigate the influence of ageing process in microstrucure behaviour of Al-9Zn-5Cu-4Mg cast alloy by performing SEM analysis and its correlation with hardness tests of as-cast Al-9Zn-5Cu-4Mg alloy and heat treated Al-9Zn-5Cu-4Mg cast alloy. The results show the deployment of precipitation spread over the dendrite and also the presence of second phases Mg3Zn3Al2 , Cu2FeAl7 , CuAl2, and CuMgAl2 in as-cast Al-9Zn-5Cu-4Mg alloy. The presence of all these second phases are affecting to the toughness of aluminium alloy and the presence of MgZn2 leads the impairment of hardness value of heat-treated Al-9Zn-5Cu-5Mg cast alloy.

Synthesis of nanocomposite coating based on TiO2/ZnAl layer double hydroxides; Síntesis de un revestimiento nanocompuesto basado en TiO2 / ZnAl hidróxidos dobles en capas

Energy Technology Data Exchange (ETDEWEB)

Jovanov, V.; Rudic, O.; Ranogajec, J.; Fidanchevska, E.

2017-07-01

The aim of this investigation was the synthesis of nanocomposite coatings based on Zn-Al layered double hydroxides (Zn-Al LDH) and TiO2. The Zn-Al LDH material, which acted as the catalyst support of the active TiO2 component (in the content of 3 and 10 wt. %), was synthesized by a low super saturation co-precipitation method. The interaction between the Zn-Al LDH and the active TiO2 component was accomplished by using vacuum evaporation prior to the mechanical activation and only by mechanical activation. The final suspension based on Zn-Al LDH and 10wt. % TiO2, impregnated only by mechanical activation, showed the optimal characteristics from the aspect of particle size distribution and XRD analysis. These properties had a positive effect on the functional properties of the coatings (photocatalytic activity and self-cleaning efficiency) after the water rinsing procedure. [Spanish] El objetivo de esta investigación fue la preparación de recubrimientos de nanocompuestos basados en Zn-Al hidróxidos dobles en capas (Zn-Al LDH) y TiO2. El material de LDH Zn-Al, que actuaba como catalizador del componente activo TiO2 (en el contenido de 3 y 10 en peso.%), se sintetizó por un método de co-precipitación con baja sobresaturación. La interacción entre el Zn-Al LDH y el componente activo TiO2 se llevó a cabo mediante el uso de la evaporación al vacío antes de la activación mecánica y sólo por activación mecánica. La suspensión final basada en Zn-Al LDH y 10wt. % TiO2, impregnada solamente por la activación mecánica, mostró las características óptimas desde el aspecto de la distribución de tamaño de partícula y análisis de XRD. Estas propiedades tenían un efecto positivo sobre las propiedades funcionales de los revestimientos (actividad fotocatalítica y eficiencia de auto-limpieza) después del procedimiento de aclarado de agua.

Microstructure and heat resistance of Mg-Al-Zn alloys containing metastable phase

International Nuclear Information System (INIS)

Kim, Jeong-Min; Park, Bong-Koo; Jun, Joong-Hwan; Shin, Keesam; Kim, Ki-Tae; Jung, Woon-Jae

2007-01-01

In this research microstructural studies have been made on cast specimens of AZ91 base alloys containing various amounts of Zn. As the amount of Zn addition increased up to 2%, any new Zn-containing phase did not appear while the Zn content in Mg 17 Al 12 phase continuously increased. A quasi-crystalline phase started to form at Mg 17 Al 12 phase when the added Zn content was about 3 wt.%. The tensile strength and elongation of the alloys at 175 deg. C were observed to increase significantly with increasing Zn content. The quasi-crystalline phase was found to be stable up to 300 deg. C, based on scanning electron microscopy examinations of the specimens heated at different temperatures for 24 h

Electrochemical deposition and characterization of Zn-Al layered double hydroxides (LDHs) films on magnesium alloy

Energy Technology Data Exchange (ETDEWEB)

Wu, Fengxia; Liang, Jun, E-mail: jliang@licp.cas.cn; Peng, Zhenjun; Liu, Baixing

2014-09-15

Highlights: • Zn-Al LDHs film was prepared on AZ91D Mg alloy by electrochemical deposition. • The Zn-Al LDHs film was uniform and dense with some small flaws and cracks. • The Zn-Al LDHs film had high adhesion and good corrosion protection to Mg alloy. - Abstract: A zinc-aluminum layered double hydroxides (Zn-Al LDHs) film was prepared on AZ91D magnesium (Mg) alloy substrate by electrochemical deposition method. The characteristics of the film were investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and scanning electronic microscope (SEM). It was found that the electrodeposited film was composed of crystalline Zn-Al LDHs with nitrate intercalation. The Zn-Al LDHs film was uniform and dense though there also presented some small flaws and cracks. The cross cut tape test showed that the film adhered well to the substrate. Polarization and EIS measurements revealed that the LDHs coated Mg alloy had better corrosion resistance compared to that of the uncoated one in 3.5 wt.% NaCl solution, indicating that the Zn-Al LDHs film could effectively protect Mg alloy from corrosion.

Electrochemical deposition and characterization of Zn-Al layered double hydroxides (LDHs) films on magnesium alloy

International Nuclear Information System (INIS)

Wu, Fengxia; Liang, Jun; Peng, Zhenjun; Liu, Baixing

2014-01-01

Highlights: • Zn-Al LDHs film was prepared on AZ91D Mg alloy by electrochemical deposition. • The Zn-Al LDHs film was uniform and dense with some small flaws and cracks. • The Zn-Al LDHs film had high adhesion and good corrosion protection to Mg alloy. - Abstract: A zinc-aluminum layered double hydroxides (Zn-Al LDHs) film was prepared on AZ91D magnesium (Mg) alloy substrate by electrochemical deposition method. The characteristics of the film were investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and scanning electronic microscope (SEM). It was found that the electrodeposited film was composed of crystalline Zn-Al LDHs with nitrate intercalation. The Zn-Al LDHs film was uniform and dense though there also presented some small flaws and cracks. The cross cut tape test showed that the film adhered well to the substrate. Polarization and EIS measurements revealed that the LDHs coated Mg alloy had better corrosion resistance compared to that of the uncoated one in 3.5 wt.% NaCl solution, indicating that the Zn-Al LDHs film could effectively protect Mg alloy from corrosion

Thermodynamic analysis and experimental study on the oxidation of the Zn-Al-Mg coating baths

Energy Technology Data Exchange (ETDEWEB)

Su, Xuping, E-mail: sxping@cczu.edu.cn [Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, 213164 Jiangsu (China); Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Changzhou University, 213164 Jiangsu (China); Zhou, Jie; Wang, Jianhua; Wu, Changjun; Liu, Ya; Tu, Hao; Peng, Haoping [Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, 213164 Jiangsu (China)

2017-02-28

Highlights: • The surface oxidation products of the Zn-Al-Mg melt were analyzed with XPS. • Certain Al must be added in bath containing Mg to get stable galvanizing melts. • The oxidation products vary with the bath composition. • Oxidation can be predicted in galvanizing by using the calculated phase diagrams. • The thermodynamic analysis can be used to design the practical bath melts. - Abstract: Surface oxidation of molten Zn-6Al baths containing 0.0, 3.0 and 6.0 wt. % Mg were analyzed using X-ray photoelectron spectroscopy. γ-Al{sub 2}O{sub 3} is formed on the surface of the Zn-6Al bath, while MgAl{sub 2}O{sub 4} and MgO occur at 460 °C in the Zn-6Al-3Mg and Zn-6Al-6Mg baths, respectively. Thermodynamic analysis on the oxidation of the Zn-Al-Mg baths was performed. Calculated phase diagrams at 460 °C and 560 °C show good agreements with the experimental results. MgO or MgAl{sub 2}O{sub 4} exists in almost the entire composition range of the calculated oxidation diagrams. According to the calculation, oxidation products depend on the composition and temperature of the baths. The primary and secondary oxidation products of the Zn-Al-Mg baths can be reasonably explained by oxidation phase diagrams. Utilizing these results, the favorable practical bath melts and operating conditions can be designed.

Fatigue crack behavior on a Cu-Zn-Al SMA

Directory of Open Access Journals (Sweden)

V. Di Cocco

2014-10-01

Full Text Available In recent years, mechanical property of many SMA has improved in order to introduce these alloys in specific field of industry. Main examples of these alloys are the NiTi, Cu-Zn-Al and Cu-Al-Ni which are used in many fields of engineering such as aerospace or mechanical systems. Cu-Zn-Al alloys are characterized by good shape memory properties due to a bcc disordered structure stable at high temperature called β-phase, which is able to change by means of a reversible transition to a B2 structure after appropriate cooling, and reversible transition from B2 secondary to DO3 order, under other types of cooling. In β-Cu-Zn-Al shape memory alloys, the martensitic transformation is not in equilibrium at room temperature. It is therefore often necessary to obtain the martensitic structure, using a thermal treatment at high temperature followed by quenching. The martensitic phases can be either thermally-induced spontaneous transformation, or stressinduced, or cooling, or stressing the β- phase. Direct quenching from high temperatures to the martensite phase is the most effective because of the non-diffusive character of the transformation. The martensite inherits the atomic order from the β-phase. Precipitation of many kinds of intermetallic phases is the main problem of treatment on cu-based shape memory alloy. For instance, a precipitation of α-phase occurs in many low aluminum copper based SMA alloy and presence of α-phase implies a strong degradation of shape recovery. However, Cu-Zn-Al SMA alloys characterized by aluminum contents less than 5% cover a good cold machining and cost is lower than traditional NiTi SMA alloys. In order to improve the SMA performance, it is always necessary to identify the microstructural changing in mechanical and thermal conditions, using X-Ray analyses. In this work a Cu-Zn-Al SMA alloy obtained in laboratory has been microstructurally and metallographically characterized by means of X-Ray diffraction and Light

Synthesis of nanocomposite coating based on TiO2/ZnAl layer double hydroxides

International Nuclear Information System (INIS)

Jovanov, V.; Rudic, O.; Ranogajec, J.; Fidanchevska, E.

2017-01-01

The aim of this investigation was the synthesis of nanocomposite coatings based on Zn-Al layered double hydroxides (Zn-Al LDH) and TiO2. The Zn-Al LDH material, which acted as the catalyst support of the active TiO2 component (in the content of 3 and 10 wt. %), was synthesized by a low super saturation co-precipitation method. The interaction between the Zn-Al LDH and the active TiO2 component was accomplished by using vacuum evaporation prior to the mechanical activation and only by mechanical activation. The final suspension based on Zn-Al LDH and 10wt. % TiO2, impregnated only by mechanical activation, showed the optimal characteristics from the aspect of particle size distribution and XRD analysis. These properties had a positive effect on the functional properties of the coatings (photocatalytic activity and self-cleaning efficiency) after the water rinsing procedure. [es

Soldering of Mg Joints Using Zn-Al Solders

Science.gov (United States)

Gancarz, Tomasz; Berent, Katarzyna; Skuza, Wojciech; Janik, Katarzyna

2018-04-01

Magnesium has applications in the automotive and aerospace industries that can significantly contribute to greater fuel economy and environmental conservation. The Mg alloys used in the automotive industry could reduce mass by up to 70 pct, providing energy savings. However, alongside the advantages there are limitations and technological barriers to use Mg alloys. One of the advantages concerns phenomena occurring at the interface when joining materials investigated in this study, in regard to the effect of temperature and soldering time for pure Mg joints. Eutectic Zn-Al and Zn-Al alloys with 0.05 (wt pct) Li and 0.2 (wt pct) Na were used in the soldering process. The process was performed for 3, 5, and 8 minutes of contact, at temperatures of 425 °C, 450 °C, 475 °C, and 500 °C. Selected, solidified solder-substrate couples were cross-sectioned, and their interfacial microstructures were investigated by scanning electron microscopy. The experiment was designed to demonstrate the effect of time, temperature, and the addition of Li and Na on the kinetics of the dissolving Mg substrate. The addition of Li and Na to eutectic Zn-Al caused to improve mechanical properties. Higher temperatures led to reduced joint strength, which is caused by increased interfacial reaction.

On the role of Al in ultrasonically sprayed ZnO films

Energy Technology Data Exchange (ETDEWEB)

Kurtaran, S., E-mail: skurtaran@ogu.edu.tr; Aldag, S.; Ofofoglu, G.; Akyuz, I.; Atay, F.

2017-01-01

In this work, Al incorporated ZnO films have been deposited by Ultrasonic Spray Pyrolysis technique. Behavior of Al element in the structure has been tried to be clarified by investigating the structural, optical, surface and electrical properties. Compositional analysis has been performed by EDX and Al contents in the coatings have been determined as 1.1, 2.8 and 3.1 at %. X-ray diffraction patterns have shown that all films are polycrystalline with hexagonal wurtzite structure and the dominant peak is (002) ZnO for films except the one containing the highest amount of Al. Above the Al content of 2.8 at %, appearance of new phases such as Al{sub 2}O{sub 3} and ZnAl{sub 2}O{sub 4} in XRD patterns refers a solubility limit at this doping rate. Thicknesses and optical constants (refractive index and extinction coefficient) have been determined by spectroscopic ellipsometry technique using Cauchy-Urbach model. Al doping above the solubility limit has caused ZnO films to have lower refractive index values. Also, AFM images have shown that surface morphologies of the films lose their spherical and granular texture and transform to a randomly clustered formation with sharper upper edges above the solubility limit. Transmittance and electrical resistivity measurements have shown that Al incorporation below solubility limit (1.1 and 2.8 at %) allows maintaining the transparency together with low resistivity values. These films have value to work on and may be promising materials for optoelectronic applications. - Highlights: • Resistivity was evaluated in terms of solubility limit using different mechanisms. • Spectroscopic ellipsometry was used to determine the optical constants. • Samples with 1.1–3.1 at %Al were obtained to express the behavior of Al.

Estructura y textura de la fase Al₃CaZn en una chapa laminada de la aleación superplástica Al-5 % Ca-5 % Zn

Directory of Open Access Journals (Sweden)

Pérez-Pardo, M. T.

1998-05-01

Full Text Available The structure of the intermetallic phase Al₃CaZn present in the superplastic sheet alloy Al-5 % Ca-5 % Zn has been determined by means of x-ray diffraction (XRD and electrón diffraction (TEM. Also, the texture of this phase has been studied by means of pole figures and the orientation distribution function (ODF. The Al-5 % Ca-5 % Zn alloy is formed by a fine grained aluminum matrix (d ≈ 2-3 μm and 20 % vol. of Al₃CaZn in the form of round-shaped particles with 0.2-0.5 μm diameter. This alloy undergoes superplastic behavior in a wide range of strain rates and temperatures. It has been found in this work that the structure of the second phase is body-centered tetragonal, with lattice parameters a = b = 0.422 nm and c = 1.131 nm. The texture of the alloy is formed by the fiber <001>, i.e., the crystallites are oriented preferentially with the c-axis perpendicular to the rolling plane. The texture sharpens after severe annealings.

En este trabajo se ha determinado la estructura de la fase Al₃CaZn, presente en una chapa laminada de la aleación Al-5 % Ca-5 % Zn, mediante técnicas de difracción de rayos X (DRX y difracción de electrones (MET. Además, se ha estudiado su textura mediante figuras de polos y la función de distribución de orientaciones (FDO. La aleación Al-5 % Ca-5 % Zn objeto de este estudio consta de una matriz de aluminio de grano fino (d ≈ 2-3 μm y un 20 % vol. de la fase Al₃CaZn. Esta segunda fase está presente en el material de partida en forma de partículas esferoidales de 0,2 - 0,5 μm de diámetro. La aleación presenta un comportamiento superplástico en un amplio intervalo tanto de velocidades de deformación como de temperaturas. Se ha encontrado que la fase Al₃CaZn posee una estructura tetragonal centrada, con parámetros de red a = b= 0,422 nm y c = 1,131 nm. Presenta, además, una textura de fibra <001>, en la

Characteristics of hydrogen co-doped ZnO : Al thin films

International Nuclear Information System (INIS)

Lee, S H; Lee, T S; Lee, K S; Cheong, B; Kim, W M; Kim, Y D

2008-01-01

ZnO films co-doped with H and Al (HAZO) were prepared by sputtering ZnO targets containing 1 wt% Al 2 O 3 on Corning glass at a substrate temperature of 150 deg. C with Ar and H 2 /Ar gas mixtures. The effects of hydrogen addition to Al-doped ZnO (AZO) films with low Al content on the electrical, the optical and the structural properties of the as-grown films as well as the vacuum- and air-annealed films were examined. Secondary ion mass spectroscopy analysis showed that the hydrogen concentration increased with increasing H 2 in sputter gas. For the as-deposited films, the free carrier number increased with increasing H 2 . The Hall mobility increased at low hydrogen content, reaching a maximum before decreasing with a further increase of H 2 content in sputter gas. Annealing at 300 deg. C resulted in the removal of hydrogen, causing a decrease in the carrier concentration. It was shown that hydrogen might exist as single isolated interstitial hydrogen bound with oxygen, thereby acting like an anionic dopant. Also, it was shown that the addition of hydrogen to ZnO films doped with low metallic dopant concentration could yield transparent conducting films with very low absorption loss as well as with proper electrical properties, which is suitable for thin film solar cell applications

In situ corrosion analysis of Al-Zn-In-Mg-Ti-Ce sacrificial anode alloy

International Nuclear Information System (INIS)

Ma Jingling; Wen Jiuba; Zhai Wenxia; Li Quanan

2012-01-01

The corrosion behaviour of Al-5Zn-0.02In-1Mg-0.05Ti-0.5Ce (wt.%) alloy has been investigated by immersion test, scanning electron microscopy, energy dispersive X-ray detector, electrochemical impedance spectroscopy and electrochemical noise. The results show that there exist different corrosion types of the alloy in 3.5% NaCl solution with the immersion time. At the initial stage of immersion, pitting due to the precipitates predominates the corrosion with a typical inductive loop at low frequencies in electrochemical impedance spectroscopy. The major precipitates of the alloy are MgZn 2 and Al 2 CeZn 2 particles. The corrosion potentials of the bulk MgZn 2 and Al 2 CeZn 2 alloys are negative with respect to that of α-Al, so the MgZn 2 and Al 2 CeZn 2 precipitates can act as activation centre and cause the pitting. In the late corrosion, a relative uniform corrosion predominates the corrosion process controlled by the dissolution/precipitation of the In ions and characterized by a capacitive loop at medium-high frequencies in electrochemical impedance spectroscopy. The potential noise of the pitting shows larger amplitude fluctuation and lower frequency, but the potential noise of the uniform corrosion occurs with smaller amplitude fluctuation and higher frequency.

Effect of Al and Fe doping in ZnO on magnetic and magneto-transport properties

International Nuclear Information System (INIS)

Kumar, Santosh; Deepika; Tripathi, Malvika; Vaibhav, Pratyush; Kumar, Aman; Kumar, Ritesh; Choudhary, R.J.; Phase, D.M.

2016-01-01

The structural, magnetic and magneto-transport of undoped ZnO, Zn_0_._9_7Al_0_._0_3O, Zn_0_._9_5Fe_0_._0_5O and Zn_0_._9_2Al_0_._0_3Fe_0_._0_5O thin films grown on Si(100) substrate using pulsed laser deposition were investigated. The single phase nature of the films is confirmed by X-ray diffraction and Raman spectroscopy measurements. The possibility of Fe metal cluster in Fe doped/co-doped films is ruled out by Fe 2p core level photoelectron spectra. From O 1s core level spectra it is observed that oxygen vacancy is present in all the films. The undoped ZnO film shows magnetic ordering below ∼175 K, whereas Fe doped/codoped samples show magnetic ordering even at 300 K. The Al doped sample reveals paramagnetic behavior. The magneto-transport measurements suggest that the mobile carriers undergo exchange interaction with local magnetic moments. - Highlights: • Al, Fe, Al–Fe co-doped and undoped films of ZnO are deposited on Si by PLD. • Single phase (002) oriented Wurtzite ZnO phase is formed for all films. • Fe doped and Fe–Al co-doped ZnO films reveal magnetic hysteresis at 300 K. • Negative magnetoresistance is observed in undoped and Fe–Al co-doped ZnO film. • It is apparent that charge carriers are coupled with the local magnetic moment.

Effect of Al and Fe doping in ZnO on magnetic and magneto-transport properties

Energy Technology Data Exchange (ETDEWEB)

Kumar, Santosh, E-mail: skphysics@yahoo.co.in [Department of Physics, College of Commerce, Arts & Science, Patna 800020, Bihar (India); Deepika [Department of Physics, College of Commerce, Arts & Science, Patna 800020, Bihar (India); Tripathi, Malvika [UGC DAE, Consortium for scientific research, Indore 452001, Madhya Pradesh (India); Vaibhav, Pratyush [Jaypee University of Engineering and Technology, Guna 473226, Madhya Pradesh (India); Kumar, Aman [Indian Institute of Technology, Roorkee (India); Kumar, Ritesh [Department of Physics, College of Commerce, Arts & Science, Patna 800020, Bihar (India); Choudhary, R.J., E-mail: ram@csr.res.in [UGC DAE, Consortium for scientific research, Indore 452001, Madhya Pradesh (India); Phase, D.M. [UGC DAE, Consortium for scientific research, Indore 452001, Madhya Pradesh (India)

2016-12-01

The structural, magnetic and magneto-transport of undoped ZnO, Zn{sub 0.97}Al{sub 0.03}O, Zn{sub 0.95}Fe{sub 0.05}O and Zn{sub 0.92}Al{sub 0.03}Fe{sub 0.05}O thin films grown on Si(100) substrate using pulsed laser deposition were investigated. The single phase nature of the films is confirmed by X-ray diffraction and Raman spectroscopy measurements. The possibility of Fe metal cluster in Fe doped/co-doped films is ruled out by Fe 2p core level photoelectron spectra. From O 1s core level spectra it is observed that oxygen vacancy is present in all the films. The undoped ZnO film shows magnetic ordering below ∼175 K, whereas Fe doped/codoped samples show magnetic ordering even at 300 K. The Al doped sample reveals paramagnetic behavior. The magneto-transport measurements suggest that the mobile carriers undergo exchange interaction with local magnetic moments. - Highlights: • Al, Fe, Al–Fe co-doped and undoped films of ZnO are deposited on Si by PLD. • Single phase (002) oriented Wurtzite ZnO phase is formed for all films. • Fe doped and Fe–Al co-doped ZnO films reveal magnetic hysteresis at 300 K. • Negative magnetoresistance is observed in undoped and Fe–Al co-doped ZnO film. • It is apparent that charge carriers are coupled with the local magnetic moment.

Alizarin red S dye removal from contaminated water on calcined [Mg/Al, Zn/Al and MgZn/Al]-LDH

Science.gov (United States)

Aissat, Miloud; Hamouda, Sara; Benhadria, Naceur; Chellali, Rachid; Bettahar, Noureddine

2018-05-01

The waste water rejected by the textile industries is loaded with organic dyes, responsible for the high color present in the effluents. Some dyes and / or their degradation products could be carcinogenic and may have mutagenic properties. The rapid growth of the global economy has caused many environmental problems with a huge pollution problem. The abuse use of chemicals product is an environmental toxicological problem. The consequences can be serious for water resources. In this perspective, our study comes to participate with new means of depollution using new materials with interesting properties in the treatment of pollution. Among these materials, LDHs whose synthesis is easy and inexpensive can be a tool in the treatment of water Polluted [1]. Our contribution consists in using HDL as a means of sorption of dyes which are considered as polluting agents of waters especially for the industry textile. This study considers the removal of the Alizarine Red S (AR) from water on calcined MgAl,ZnAL and MgZnAL-layered double hydroxides. The different LDH was prepared by copreprecipation method. The materials was obtained for molar ratios R =2 for the different LDH. The carbonated layered Calcination of these solids leads to the formation of mixed oxides which have the property of being able to be regenerated by adsorbing new anionic entities. Adsorbents and adsorption products were characterized by physicochemical techniques. The structural characterization of the material was carried out by X-ray diffraction, infrared spectroscopy (FTIR). Dosages of the polluted solutions were monitored by UV-Visible spectrometry.

Converting hcp Mg-Al-Zn alloy into bcc Mg-Li-Al-Zn alloy by electrolytic deposition and diffusion of reduced lithium atoms in a molten salt electrolyte LiCl-KCl

International Nuclear Information System (INIS)

Lin, M.C.; Tsai, C.Y.; Uan, J.Y.

2007-01-01

A body-centered cubic (bcc) Mg-12Li-9Al-1Zn (wt.%) alloy was fabricated in air by electrolysis from LiCl-KCl molten salt at 500 deg. C. Electrolytic deposition of Li atoms on cathode (Mg-Al-Zn alloy) and diffusion of the Li atoms formed the bcc Mg-Li-Al-Zn alloy with 12 wt.% Li and only 0.264 wt.% K. Low K concentration in the bcc Mg alloy strip after the electrolysis process resulted from 47% atomic size misfit between K and Mg atoms and low solubility of K in Mg matrix

Chitosan/ZnAl_2O_4 films: structural evaluation and photoluminescent

International Nuclear Information System (INIS)

Araujo, P.M.A.G.; Costa, A.C.F.M.

2014-01-01

The photoluminescent materials have been the focus of intense research and applications in optics, electronics and biological areas. This work reports obtaining chitosan/ZnAl_2O_4 film in proportions of 1: 1, 1: 2, 1: 3, 1:4 to 1:5 by weight, and assess the structural properties of the films and photoluminescence. The samples were characterized by XRD, FTIR, emission and excitation. By XRD was found that all samples showed characteristic peaks of chitosan and ZnAl_2O_4. The FTIR spectra for all concentrations of Qs/NPs films exhibit characteristic bands of Qs and trend banding of ions ZnAl_2O_4. The emission and excitation spectra revealed the presence of a broadband processes associated with charge transfer to the Al"3"+ O"2"-, all samples showed good photoluminescent properties being that higher intensities of photoluminescence gave to the film concentration 1:4 being promising for photoelectronic applications. (author)

The effects of lanthanum on microstructure and electrochemical properties of Al-Zn-In based sacrificial anode alloys

International Nuclear Information System (INIS)

Ma Jingling; Wen Jiuba

2009-01-01

In order to improve the non-uniform corrosion of Al-0.5Zn-0.03In-1Mg-0.05Ti alloys, Al-5Zn-0.03In-1Mg-0.05Ti-xLa (x = 0.3, 0.5 and 0.7 wt.%) alloys were developed. Microstructures and electrochemical properties of the alloys were investigated. The results show that the optimal microstructures and electrochemical properties are obtained in Al-5Zn-0.03In-1Mg-0.05Ti-0.5La alloy. The main precipitate phase is Al 2 LaZn 2 particles. The excellent electrochemical properties of Al-5Zn-0.03In-1Mg-0.05Ti-0.5La alloy is mainly attributed to fine grains and grain boundaries containing fine Al 2 LaZn 2 precipitates. At the same time the fine grains can improve the non-uniform corrosion of Al-0.5Zn-0.03In-1Mg-0.05Ti alloy.

Solid-phase crystallization of amorphous silicon on ZnO:Al for thin-film solar cells

Energy Technology Data Exchange (ETDEWEB)

Becker, C.; Conrad, E.; Dogan, P.; Fenske, F.; Gorka, B.; Haenel, T.; Lee, K.Y.; Rau, B.; Ruske, F.; Weber, T.; Gall, S.; Rech, B. [Helmholtz-Zentrum Berlin fuer Materialien und Energie (formerly Hahn-Meitner-Institut Berlin), Kekulestr. 5, D-12489 Berlin (Germany); Berginski, M.; Huepkes, J. [Institute of Photovoltaics, Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany)

2009-06-15

The suitability of ZnO:Al thin films for polycrystalline silicon (poly-Si) thin-film solar cell fabrication was investigated. The electrical and optical properties of 700 -nm-thick ZnO:Al films on glass were analyzed after typical annealing steps occurring during poly-Si film preparation. If the ZnO:Al layer is covered by a 30 nm thin silicon film, the initial sheet resistance of ZnO:Al drops from 4.2 to 2.2 {omega} after 22 h annealing at 600 C and only slightly increases for a 200 s heat treatment at 900 C. A thin-film solar cell concept consisting of poly-Si films on ZnO:Al coated glass is introduced. First solar cell results will be presented using absorber layers either prepared by solid-phase crystallization (SPC) or by direct deposition at 600 C. (author)

Highly conductive Al-doped tetra-needle-like ZnO whiskers prepared by a solid state method

International Nuclear Information System (INIS)

Wan Cuifeng; Tan Hairen; Jin Shengming; Yang Huaming; Tang Motang; He Jing

2008-01-01

Tetra-needle-like zinc oxide whiskers (T-ZnO W ) were doped with Al 3+ by a solid state method. In this study, modification conditions were thoroughly investigated to obtain low resistivity T-ZnO W , without destroying the tetra-needle-like structure. The Al-doped T-ZnO W was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transition infrared (FT-IR) spectra and electrical resistance measurement. The SEM and XRD results indicated that the tetra-needle-like structure of ZnO whiskers could be well maintained after modification and the doped (0 0 2) face was preferred. FT-IR results showed that the decrease of resistivity of Al-doped T-ZnO W resulted from formation of [AlO 4 ] configuration in T-ZnO W bulk. Experiment results showed that the annealing temperature, doping concentration and type of Al sources affected the resistivity of T-ZnO W considerably. The optimum Al-doped concentration was 7.0 at.% and the resistivity of T-ZnO W could be considerably decreased from 10 8 to 10 2 Ω cm

Friction Stir Welding-assisted Diffusion Bond of Al/Zn/Mg Lap Joint

Directory of Open Access Journals (Sweden)

JIN Yu-hua

2018-03-01

Full Text Available Dissimilar materials welding between 2mm-thick AZ31B Mg alloy and 6061 Al alloy plates in overlap form was performed using the friction stir-induced diffusion bond with zinc foil as the interlayer. The microstructure and mechanical properties of the Al/Zn/Mg lap joints were analyzed by means of SEM, EPMA, XRD, tensile experiment and Vickers hardness test. The results show that diffusion layer consists of Al enrichment zone, Al5Mg11Zn4 layer and Mg-Zn eutectic zone at proper rotation speed; however, when rotation speed is low, the residual zinc interlayer remains in the diffusion layer; when rotation speed is high, the Al-Mg intermetallic compounds are present again. Due to the existence of intermetallic compounds in diffusion layer, its microhardness is significantly higher than that of base metal. The addition of zinc foil can improve the mechanical properties of Al/Mg lap joints. According to analysis on the fracture, joint failure occurs in the diffusion layer near to Al side.

Fabrication of hierarchical porous ZnO-Al2O3 microspheres with enhanced adsorption performance

Science.gov (United States)

Lei, Chunsheng; Pi, Meng; Xu, Difa; Jiang, Chuanjia; Cheng, Bei

2017-12-01

Hierarchical porous ZnO-Al2O3 microspheres were fabricated through a simple hydrothermal route. The as-prepared hierarchical porous ZnO-Al2O3 composites were utilized as adsorbents to remove organic dye Congo red (CR) from water. The ZnO-Al2O3 composites had morphology of microspheres with diameters in the range of 12-16 μm, which were assembled by nanosheets with thicknesses of approximately 60 nm. The adsorption kinetics of CR onto the ZnO-Al2O3 composites was properly fitted by the pseudo-second-order kinetic model. The equilibrium adsorption data were perfectly described by the Langmuir isotherm and had a maximum adsorption capacity that reached 397 mg/g, which was significantly higher than the value of the pure alumina (Al2O3) and zinc oxide (ZnO) samples. The superior CR removal efficiency of the ZnO-Al2O3 composites was attributed to its well-developed hierarchical porous structures and larger specific surface area (201 m2/g), which were conducive to the diffusion and adsorption of CR molecules. Moreover, the regeneration study reveals that the ZnO-Al2O3 composites have suitable stability and reusability. The results also indicate that the as-prepared sample can act as a highly effective adsorbent in anionic dye removal from wastewater.

A Study on Development of High Strength Al-Zn Based alloy for Die Casting Ⅲ

Energy Technology Data Exchange (ETDEWEB)

Shin, Sang-Soo; Park, Ik-Min [Pusan National University, Busan (Korea, Republic of); Yeom, Gil-Young; Lim, Kyoung-Mook [Korea Institute of Industrial Technology, Incheon (Korea, Republic of); Son, Hyun-Jin [Oh-Sung Co. Ltd., Siheung (Korea, Republic of)

2015-09-15

In this study, the microstructural evolution and various characteristics of Al-20⁓45wt%Zn alloys were investigated. In terms of microstructure, as the amount of Zn addition to the alloys increased, the α-phase size decreased and the α+η non-equilibrium solidification phase fraction increased. Also, increasing Zn content improved the wear resistance of the alloys, but reduced the damping capacity and toughness of the alloys. Their physical properties of the Al-Zn alloy with high Zn content, specifically the wear resistance and toughness, were superior to those of commercial ALDC12 alloys for die-casting. Based on these results, we considered the possibility of application of the developed Al-Zn alloy as a structural material.

A Study on Development of High Strength Al-Zn Based alloy for Die Casting Ⅲ

International Nuclear Information System (INIS)

Shin, Sang-Soo; Park, Ik-Min; Yeom, Gil-Young; Lim, Kyoung-Mook; Son, Hyun-Jin

2015-01-01

In this study, the microstructural evolution and various characteristics of Al-20⁓45wt%Zn alloys were investigated. In terms of microstructure, as the amount of Zn addition to the alloys increased, the α-phase size decreased and the α+η non-equilibrium solidification phase fraction increased. Also, increasing Zn content improved the wear resistance of the alloys, but reduced the damping capacity and toughness of the alloys. Their physical properties of the Al-Zn alloy with high Zn content, specifically the wear resistance and toughness, were superior to those of commercial ALDC12 alloys for die-casting. Based on these results, we considered the possibility of application of the developed Al-Zn alloy as a structural material.

Formation of crystalline Zn-Al layered double hydroxide precipitates on γ-alumina: the role of mineral dissolution.

Science.gov (United States)

Li, Wei; Livi, Kenneth J T; Xu, Wenqian; Siebecker, Matthew G; Wang, Yujun; Phillips, Brian L; Sparks, Donald L

2012-11-06

To better understand the sequestration of toxic metals such as nickel (Ni), zinc (Zn), and cobalt (Co) as layered double hydroxide (LDH) phases in soils, we systematically examined the presence of Al and the role of mineral dissolution during Zn sorption/precipitation on γ-Al(2)O(3) (γ-alumina) at pH 7.5 using extended X-ray absorption fine structure spectroscopy (EXAFS), high-resolution transmission electron microscopy (HR-TEM), synchrotron-radiation powder X-ray diffraction (SR-XRD), and (27)Al solid-state NMR. The EXAFS analysis indicates the formation of Zn-Al LDH precipitates at Zn concentration ≥0.4 mM, and both HR-TEM and SR-XRD reveal that these precipitates are crystalline. These precipitates yield a small shoulder at δ(Al-27) = +12.5 ppm in the (27)Al solid-state NMR spectra, consistent with the mixed octahedral Al/Zn chemical environment in typical Zn-Al LDHs. The NMR analysis provides direct evidence for the existence of Al in the precipitates and the migration from the dissolution of γ-alumina substrate. To further address this issue, we compared the Zn sorption mechanism on a series of Al (hydr)oxides with similar chemical composition but differing dissolubility using EXAFS and TEM. These results suggest that, under the same experimental conditions, Zn-Al LDH precipitates formed on γ-alumina and corundum but not on less soluble minerals such as bayerite, boehmite, and gibbsite, which point outs that substrate mineral surface dissolution plays an important role in the formation of Zn-Al LDH precipitates.

Structural investigation of ZnO:Al films deposited on the Si substrates by radio frequency magnetron sputtering

International Nuclear Information System (INIS)

Chen, Y.Y.; Yang, J.R.; Cheng, S.L.; Shiojiri, M.

2013-01-01

ZnO:Al films 400 nm thick were prepared on (100) Si substrates by magnetron sputtering. Energy dispersive X-ray spectroscopy and transmission electron microscopy (TEM) revealed that in the initial stage of the deposition, an amorphous silicon oxide layer about 4 nm thick formed from damage to the Si substrate due to sputtered particle bombardment and the incorporation of Si atoms with oxygen. Subsequently, a crystalline Si (Zn) layer about 30 nm thick grew on the silicon oxide layer by co-deposition of Si atoms sputtered away from the substrate with Zn atoms from the target. Finally, a ZnO:Al film with columnar grains was deposited on the Si (Zn) layer. The sputtered particle bombardment greatly influenced the structure of the object films. The (0001) lattice fringes of the ZnO:Al film were observed in high-resolution TEM images, and the forbidden 0001 reflection spots in electron diffraction patterns were attributed to double diffraction. Therefore, the appearance of the forbidden reflection did not imply any ordering of Al atoms and/or O vacancies in the ZnO:Al film. - Highlights: • ZnO:Al films were deposited on (100) Si substrate using magnetron sputtering. • An amorphous silicon oxide layer with a thickness of 4 nm was formed on Si substrate. • Crystalline Si (Zn) layer about 30 nm thick grew on amorphous silicon oxide layer. • ZnO:Al film comprising columnar grains was deposited on the Si(Zn) layer. • Lattice image of the ZnO:Al film has been interpreted

Characterization of nanocrystalline ZnO:Al films by sol-gel spin coating method

Energy Technology Data Exchange (ETDEWEB)

Gareso, P. L., E-mail: pgareso@gmail.com; Rauf, N., E-mail: pgareso@gmail.com; Juarlin, E., E-mail: pgareso@gmail.com [Department of Physics, Faculty of Mathematics and Natural Sciences, Hasanuddin University, Makassar 90245 (Indonesia); Sugianto,; Maddu, A. [Department of Physics, Faculty of Mathematics and Natural Sciences, Bogor Institute of Culture, IPB Bogor (Indonesia)

2014-09-25

Nanocrystalline ZnO films doped with aluminium by sol-gel spin coating method have been investigated using optical transmittance UV-Vis and X-ray diffraction (X-RD) measurements. ZnO films were prepared using zinc acetate dehydrate (Zn(CH{sub 3}COO){sub 2}@@‡2H{sub 2}O), ethanol, and diethanolamine (DEA) as a starting material, solvent, and stabilizer, respectively. For doped films, AlCl{sub 3} was added to the mixture. The ZnO:Al films were deposited on a transparent conductive oxide (TCO) substrate using spin coating technique at room temperature with a rate of 3000 rpm in 30 sec. The deposited films were annealed at various temperatures from 400°C to 600°C during 60 minutes. The transmittance UV-Vis measurement results showed that after annealing at 400°C, the energy band gap profile of nanocrystalline ZnO:Al film was a blue shift. This indicated that the band gap of ZnO:Al increased after annealing due to the increase of crystalline size. As the annealing temperature increased the bandgap energy was a constant. In addition to this, there was a small oscillation occurring after annealing compared to the as–grown samples. In the case of X-RD measurements, the crystalinity of the films were amorphous before annealing, and after annealing the crystalinity became enhance. Also, X-RD results showed that structure of nanocrystalline ZnO:Al films were hexagonal polycrystalline with lattice parameters are a = 3.290 Å and c = 5.2531 Å.

Effect of Ce on Casting Structure of Near-rapidly Solidified Al-Zn-Mg-Cu Alloy

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HUANG Gao-ren

2017-11-01

Full Text Available Through using XRD,DSC,SEM,EDS and other modern analysis methods, the effects of rare earth element Ce on microstructure and solidification temperature of Al-Zn-Mg-Cu under different cooling rates were studied, the principle of Ce on grain refining and melt cleaning of alloys was analyzed and discussed. The results show that MgZn2 phase and α-Al matrix are the main precipitations, Al,Cu,Mg and other elements dissolve in MgZn2 phase, a new phase Mg(Zn, Cu, Al2 is formed, solute elements in the grain boundary have higher concentration, eutectic reaction takes place between MgZn2 and α-Al, lamellar eutectic structure is generated. The addition of Ce decreases the dendritic arm spacing,reduces the layer spacing between eutectic phases and refines the eutectic structure and the grain significantly, and inhibits the appearance of the impurity phase Al7Cu2Fe in aluminum alloys. The addition of Ce also reduces the precipitation temperature of α-Al matrix and eutectic phase by 6.4℃ and 5.6℃ respectively.

Plasmonics effect of Ag nanoislands covered n-Al:ZnO/p-Si heterostructure

Energy Technology Data Exchange (ETDEWEB)

Venugopal, N., E-mail: venu369@gmail.com; Kaur, Gurpreet, E-mail: gkaurdnt@iitr.ernet.in; Mitra, Anirban, E-mail: mitrafph@iitr.ernet.in

2014-11-30

Highlights: • Effect of Ag plasmonic nanoislands on n-aluminum doped zinc oxide (Al:ZnO)/p-silicon (p-Si) heterostructure device. • Morphology of Ag nanoisland in consequence with the optical (absorbance and photoluminescence) and electrical properties of the device. • Ag nanoisland/Al:ZnO heterostructure shows remarkable improvement of absorbance in both visible and UV region compare to the bare silicon. • Near band edge emission in photoluminescence has been enhanced with the deposition of Ag nanoisland. • Dark and illumination current density also increases with the deposition of Ag nanoisland. - Abstract: A plasmonic heterostructure of Ag (nanoisland)/n-Al:ZnO/p-Si is fabricated using pulsed laser deposition and thermal evaporation method. In this structure Al:ZnO plays an important role of transparent conductive oxide (spacer layer) as well as the rectifying junction with silicon. By introducing the silver nanoislands on Al:ZnO, light harvesting has been enhanced because of plasmonic and light scattering effect. Morphology of Ag nanoparticles in consequence with the optical and electrical properties of the device has been studied. Optical reflection measurement of the device with Ag nanoisland shows remarkable improvement in both visible and UV regions compared to the bare n-Al:ZnO/p-Si heterostructure. Near band edge emission in photoluminescence has been enhanced with the deposition of Ag nanoislands. Dark and illumination current density has also been increased with the deposition of Ag nanoisland. Our experimental results suggest that integration of Ag nanoislands may help to improve the efficiency of hybrid silicon based photonic devices.

Determination of chemical state of Al doping element in ZnO layer

International Nuclear Information System (INIS)

Csik, A.; Toth, J.; Lovics, R.; Takats, V.; Hakl, J.; Vad, K.

2011-01-01

Complete text of publication follows. Transparent and conducting oxides (TCO) thin films are very important from the scientific and technological point of view. The coexistence of electrical conductivity and optical transparency in these materials makes it possible to use them in modern technologies: transparent electrodes for flat panel displays and photovoltaic cells, low emissivity windows, transparent thin films transistors, light emitting diodes. One of the important TCO semiconductors is the impurity-doped zinc-oxide (ZnO) layer, for example aluminium doped zinc-oxide layer (AZO), due to its unique physical and chemical properties. It has wide band gap (3.44 eV) and large exciton binding energy (60 meV). ZnO thin layers have a great interest for potential applications in optical and optoelectronic devices. Furthermore, high quality single crystal ZnO wafers has already been available as a result of new developments in ZnO growth technologies with the capability to scale up wafer size, which is an important factor for increasing efficiency of solar cells. Nonetheless, in order to enable the use of ZnO layers with enhanced electrical properties, higher conductivities can be obtained by doping with donor elements such as aluminium, gallium, indium, boron or fluorine. Investigation of p-type doping possibilities, diffusion processes and thermal stability of these layers are in the focus of interest in the interpretation of their optical and electrical properties, and the prediction of their lifetime. In our SNMS/SIMS-XPS laboratory, experiments on TCO layered structures were carried on. Depth profile and chemical state analyses of ZnO/AlO/ZnO layered structures were performed by Secondary Neutral Mass Spectrometry (SNMS) and X-ray photoelectron spectroscopy (XPS). The samples were produced by atomic layer deposition technique with the following layered structure: between a few hundred atomic layers of ZnO was an AlO atomic layer. The SNMS was used for depth

Photocatalytic Performance of ZnO: Al Films under Different Light Sources

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Prashant Pradhan

2012-01-01

Full Text Available ZnO and Al doped ZnO films were produced by spray pyrolysis. The films were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, UV-vis spectroscopy, and photoluminescence. Their photocatalytic activity was evaluated by the decomposition of the methyl orange dye using different light sources: ultraviolet light, artificial white light, and direct sunlight. The films were also tested under darkness for comparison. The ZnO films were able to degrade the test pollutant under UV and sunlight in more than a 60% after 180 min of irradiation and a scarce degradation was obtained using white light. However, the Al doped ZnO films presented a very high degradation rate not only under UV and sunlight (100% degradation, but also under white light (90% degradation after the same irradiation time. An unexpected high degradation was also obtained in the dark, which indicates that a nonphotonic process is taking place parallel to the photocatalytic process. This can be due to the extra electrons—provided by the aluminum atoms—that migrate to the surface and produce radicals favoring the decomposition process even in the dark. The high activity achieved by the ZnO: Al films under natural conditions can be potentially applied to water treatment processes.

Electronic and atomic structure of complex defects in Al- and Ga-highly doped ZnO films

Energy Technology Data Exchange (ETDEWEB)

Menéndez-Proupin, Eduardo [Instituto de Energía Solar, Universidad Politécnica de Madrid (UPM), Ciudad Universitaria, 28040 Madrid (Spain); Departamento de Física, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 780-0003 Ñuñoa, Santiago (Chile); Palacios, Pablo, E-mail: pablo.palacios@upm.es [Instituto de Energía Solar, Universidad Politécnica de Madrid (UPM), Ciudad Universitaria, 28040 Madrid (Spain); Dpt. FAIAN, E.T.S.I. Aeronáutica y del Espacio, UPM, Pz. Cardenal Cisneros 3, 28040 Madrid (Spain); Wahnón, Perla [Instituto de Energía Solar, Universidad Politécnica de Madrid (UPM), Ciudad Universitaria, 28040 Madrid (Spain); Dpt. TFO, E.T.S.I. Telecomunicación, UPM, Ciudad Universitaria, 28040 Madrid (Spain)

2015-06-15

Point defects in Ga- and Al-doped ZnO thin films are studied by means of first principles electronic structure calculations. Candidate defects are identified to explain recently observed differences in electrical and spectroscopic behavior of both systems. Substitutional doping in Ga–ZnO explain the metallic behavior of the electrical properties. Complexes of interstitial oxygen with substitutional Ga can behave as acceptor and cause partial compensation, as well as gap states below the conduction band minimum as observed in photoemission experiments. Zn vacancies can also act as compensating acceptors. On the other hand, the semiconducting behavior of Al–ZnO and the small variation in the optical gap compared with pure ZnO, can be explained by almost complete compensation between acceptor Zn vacancies and substitutional Al donors. Interstitial Al can also be donor levels and can be the origin of the small band observed in photoemission experiments below the Fermi level. Combinations of substitutional Al with interstitial oxygen can act simultaneously as compensating acceptor and generator of the mentioned photoemission band. The theoretical calculations have been done using density functional theory (DFT) within the generalized gradient approximation with on-site Coulomb interaction. In selected cases, DFT calculations with semilocal-exact exchange hybrid functionals have been performed. Results explain photoelectron spectra of Ga–ZnO and Al–ZnO at the corresponding doping levels. - Highlights: • Defects in Ga- and Al-heavy-doped ZnO films are studied by quantum calculations. • Defects compatible with electrical, optical, and HAXPES spectra are proposed. • Doping efficiency is reduced by Zn vacancies and O interstitials. • HAXPES bands near the Fermi level are induced by Al{sub i}, and complexes Ga{sub Zn}-O{sub i}, and Al{sub Zn}-O{sub i}.

Fabrication of ZnAl mixed metal-oxides/RGO nanohybrid composites with enhanced photocatalytic activity under visible light

Science.gov (United States)

Ni, Jie; Xue, Jinjuan; Shen, Jing; He, Guangyu; Chen, Haiqun

2018-05-01

The ZnAl mixed metal-oxides (MMOs)/graphene nanocomposites were successfully fabricated by a facile hydrothermal method combined with a calcination process. The thermal treatment enables simultaneously the formation of ZnO/ZnAl2O4 heterogeneous structure, which are uniformly decorated on the surface of graphene, accompanying with the reduction of graphene oxide. The as-prepared heterostructure photocatalysts were well characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectroscopy (DRS) to conduct investigations into the phase structures, microstructure and optical capability. The ZnAl MMO/RGO20 composite displayed favorable adsorption property and photo-degradation efficiency for Ciprofloxacin (CIP) aqueous solution under visible light. The photo-degradation efficiency of the as-prepared ZnAl MMO/RGO20 was 3.0 and even 4.6 times higher than that of ZnAl MMO and pure ZnAl LDH, respectively. The improvement of photocatalytic performance is ascribed to the synergistic effect of heterogeneous structure coupled with graphene, which realizes efficient charge separation efficiency, enlarged visible light adsorption range, and chemical stability of hybrid nanocomposite. The results of EIS, PL and photocurrent response also explained the best performance of ZnAl MMO/RGO20 nanocomposite. Besides, the mechanism of ZnAl MMO/RGO20 photocatalytic system was proposed and analyzed in detail.

Stability and band offsets between c-plane ZnO semiconductor and LaAlO3 gate dielectric

Science.gov (United States)

Wang, Jianli; Chen, Xinfeng; Wu, Shuyin; Tang, Gang; Zhang, Junting; Stampfl, C.

2018-03-01

Wurtzite-perovskite heterostructures composed of a high dielectric constant oxide and a wide bandgap semiconductor envision promising applications in field-effect transistors. In the present paper, the structural and electronic properties of LaAlO3/ZnO heterojunctions are investigated by first-principles calculations. We study the initial adsorption of La, Al, and oxygen atoms on ZnO (0001) and (000 1 ¯ ) surfaces and find that La atoms may occupy interstitial sites during the growth of stoichiometric ZnO (0001). The band gap of the stoichiometric ZnO (0001) surface is smaller than that of the stoichiometric ZnO (000 1 ¯ ) surface. The surface formation energy indicates that La or Al atoms may substitute Zn atoms at the nonstoichiometric ZnO (0001) surface. The atomic charges, electronic density of states, and band offsets are analyzed for the optimized LaAlO3/ZnO heterojunctions. There is a band gap for the LaAlO3/ZnO (000 1 ¯ ) heterostructures, and the largest variation in charge occurs at the surface or interface. Our results suggest that the Al-terminated LaAlO3/ZnO (000 1 ¯ ) interfaces are suitable for the design of metal oxide semiconductor devices because the valence and conduction band offsets are both larger than 1 eV and the interface does not produce any in-gap states.

Zn-Al Layered Double Hydroxide: Synthesis and Optical Properties

International Nuclear Information System (INIS)

Abdullah Ahmed Ali Ahmed; Zainal Abidin Talib

2011-01-01

Zn-Al-NO 3 -LDH was prepared by co-precipitation method at constant pH 7 and ratio of Zn/ Al=4. Thermal treatment was performed for LDH at various temperatures. The Powder XRD patterns showed stability in structure of LDH samples below 200 degree Celsius. Infrared spectra of samples showed the characteristic peaks of LDH and the changes of these peaks after thermal treatment above 150 degree Celsius. The energy gaps of the samples were found by diffuse reflectance spectroscopy which showed more than one energy gaps at sintered temperatures less than 200 degree Celsius. These energy gaps were assigned to the presence of NO 3 - in interlayer of LDH. At sintered temperature of 200 degree Celsius and above, the LDH samples have one energy gap which was around 3.3 eV. The photo catalytic activity increased due to ZnO crystal size increases by increasing of the sintered temperature of samples.(author)

Improvement of High-Temperature Stability of Al2O3/Pt/ZnO/Al2O3 Film Electrode for SAW Devices by Using Al2O3 Barrier Layer

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Xingpeng Liu

2017-12-01

Full Text Available In order to develop film electrodes for the surface acoustic wave (SAW devices operating in harsh high-temperature environments, novel Al2O3/Pt/ZnO/Al2O3 multilayered film electrodes were prepared by laser molecular beam epitaxy (LMBE at 150 °C. The first Al2O3 layer was used as a barrier layer to prevent the diffusion of Ga, La, and Si atoms from the La3Ga5SiO14 (LGS substrate to the film electrode and thus improved the crystalline quality of ZnO and Pt films. It was found that the resistance of the Al2O3/Pt/ZnO/Al2O3 electrode did not vary up to a temperature of 1150 °C, suggesting a high reliability of electrode under harsh high-temperature environments. The mechanism of the stable resistance of the Al2O3/Pt/ZnO/Al2O3 film electrodes at high temperature was investigated by analyzing its microstructure. The proposed Al2O3/Pt/ZnO/Al2O3 film electrode has great potential for application in high-temperature SAW devices.

Growth, etching, and stability of sputtered ZnO:Al for thin-film silicon solar cells

Energy Technology Data Exchange (ETDEWEB)

Owen, Jorj Ian

2011-07-01

Aluminum-doped zinc oxide (ZnO:Al) can fulfill many requirements in thin-film solar cells, acting as (1) a transparent contact through which the incident light is transmitted, (2) part of the back reflector, and (3) a source of light scattering. Magnetron sputtered ZnO:Al thin-films are highly transparent, conductive, and are typically texturized by post-deposition etching in a dilute hydrochloric acid (HCl) solution to achieve light scattering. The ZnO:Al thin-film electronic and optical properties, as well as the surface texture after etching, depend on the deposition conditions and the post-deposition treatments. Despite having been used in thin-film solar cells for more than a decade, many aspects regarding the growth, effects of heat treatments, environmental stability, and etching of sputtered ZnO:Al are not fully understood. This work endeavors to further the understanding of ZnO:Al for the purpose improving silicon thin-film solar cell efficiency and reducing ZnO:Al production costs. With regard to the growth of ZnO:Al, the influence of various deposition conditions on the resultant electrical and structural properties and their evolution with film thickness were studied. The surface electrical properties extracted from a multilayer model show that while carrier concentration of the surface layer saturates already at film thickness of 100 nm, the surface mobility continues to increases with film thickness, and it is concluded that electronic transport across grain boundaries limits mobility in ZnO:Al thin films. ZnO:Al deposited onto a previously etched ZnO:Al surface grows epitaxially, preserving both the original orientation and grain structure. Further, it is determined that a typical ZnO:Al used in thin-film silicon solar cells grows Zn-terminated on glass substrates. Concerning the affects of heat treatments and stability, it is demonstrated that a layer of amorphous silicon can protect ZnO:Al from degradation during annealing, and the mobility of ZnO:Al

Degradability Enhancement of Poly(Lactic Acid by Stearate-Zn₃Al LDH Nanolayers

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Mahboobeh Eili

2012-06-01

Full Text Available Recent environmental problems and societal concerns associated with the disposal of petroleum based plastics throughout the world have triggered renewed efforts to develop new biodegradable products compatible with our environment. This article describes the preparation, characterization and biodegradation study of poly(lactic acid/layered double hydroxide (PLA/LDH nanocomposites from PLA and stearate-Zn₃Al LDH. A solution casting method was used to prepare PLA/stearate-Zn₃Al LDH nanocomposites. The anionic clay Zn₃Al LDH was firstly prepared by co-precipitation method from a nitrate salt solution at pH 7.0 and then modified by stearate anions through an ion exchange reaction. This modification increased the basal spacing of the synthetic clay from 8.83 Å to 40.10 Å. The morphology and properties of the prepared PLA/stearate-Zn₃Al LDH nanocomposites were studied by X-ray diffraction (XRD, transmission electron microscope (TEM, scanning electron microscope (SEM, thermogravimetric analysis (TGA, tensile tests as well as biodegradation studies. From the XRD analysis and TEM observation, the stearate-Zn₃Al LDH lost its ordered stacking-structure and was greatly exfoliated in the PLA matrix. Tensile test results of PLA/stearate-Zn₃Al LDH nanocomposites showed that the presence of around 1.0–3.0 wt % of the stearate-Zn₃Al LDH in the PLA drastically improved its elongation at break. The biodegradation studies demonstrated a significant biodegradation rate improvement of PLA in the presence of stearate-Zn₃Al LDH nanolayers. This effect can be caused by the catalytic role of the stearate groups in the biodegradation mechanism leading to much faster disintegration of nanocomposites than pure PLA.

Immobilization of kojic acid in ZnAl-hydrotalcite like compounds

Science.gov (United States)

Ambrogi, Valeria; Perioli, Luana; Nocchetti, Morena; Latterini, Loredana; Pagano, Cinzia; Massetti, Elena; Rossi, Carlo

2012-01-01

Kojic acid (KOJ) is a melanin synthesis inhibitor widely used as skin lightening agent in topical preparations. Unfortunately it is easily susceptible to photo-oxidation, phenomenon responsible for chemical and organoleptic modifications. The aim of this work was the intercalation of KOJ in hydrotalcite-like compounds (HTlc) in order to stabilize KOJ and to reduce its photolability. Hydrotalcite containing Zn and Al (ZnAl-HTlc) was used as host to obtain the final compound ZnAl-HTlc-KOJ. The intercalation was carried out, after many attempts, by ionic exchange mechanism by means of the strong base EtO- in anhydrous ethanol/dimethylsulfoxide (DMSO) mixture as solvent in order to generate KOJ- anions. The final product was characterized by the X-ray powder diffraction (XRPD), FT-IR spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and elemental analysis. The intercalated compound was formulated in a siliconic water free self-emulsifying ointment and the in vitro release profile was evaluated. All samples (intercalation compound and its formulation) were submitted also to spectrophotometric assays in order to evaluate the matrix protective effect towards ultraviolet rays.

Non-isothermal precipitation behaviors of Al-Mg-Si-Cu alloys with different Zn contents

International Nuclear Information System (INIS)

Guo, M.X.; Zhang, Y.; Zhang, X.K.; Zhang, J.S.; Zhuang, L.Z.

2016-01-01

The non-isothermal precipitation behaviors of Al–Mg–Si–Cu alloys with different Zn contents were investigated by differential scanning calorimetry (DSC) analysis, hardness measurement and high resolution transmission electron microscope characterization. The results show that Zn addition has a significant effect on the GP zone dissolution and precipitation of Al-Mg-Si-Cu alloys. And their activation energies change with the changes of Zn content and aging conditions. Precipitation kinetics can be improved by adding 0.5 wt% or 3.0 wt%Zn, while be suppressed after adding 1.5 wt%Zn. The Mg-Si precipitates (GP zones and β″) are still the main precipitates in the Al-Mg-Si-Cu alloys after heated up to 250 °C, and no Mg-Zn precipitates are observed in the Zn-added alloy due to the occurrence of Mg-Zn precipitates reversion. The measured age-hardening responses of the alloys are corresponding to the predicted results by the established precipitation kinetic equations. Additionally, a double-hump phenomenon of hardness appears in the artificial aging of pre-aged alloy with 3.0 wt% Zn addition, which resulted from the formation of pre-β″ and β″ precipitates. Finally, the precipitation mechanism of Al-Mg-Si-Cu alloys with different Zn contents was proposed based on the microstructure evolution and interaction forces between Mg, Si and Zn atoms.

Influence of Al concentration and annealing temperature on structural, optical, and electrical properties of Al co-doped ZnO thin films

International Nuclear Information System (INIS)

Gürbüz, Osman; Kurt, İsmail; Çalışkan, Serkan; Güner, Sadık

2015-01-01

Highlights: • RF magnetron sputtering technique seems to be very efficient method for fabrication of Al doped ZnO (AZO) films. • Long range single crystalline structure improves with annealing process. • Optical properties became much better after annealing process especially for the AZO films that include high Al concentration. • Much greater conductivity with increasing Al concentration and annealing process. • AZO films have potential applicability in spintronic devices. - Abstract: The pure ZnO and Al-doped ZnO (AZO) thin films (thickness: 200 nm) were prepared on both side polished silica (SiO 2 ) substrates via RF magnetron sputtering at room temperature by using 2.5 inches high-purity ZnO (99.9%) and Al (99.9%) targets. The samples were annealed at 300 °C, 400 °C and 500 °C for 45 min in N 2 ambient in quartz annealing furnace system, respectively. We investigated the effects of various Al concentrations and annealing treatment on the structural, electrical, and optical properties of films. The preferred crystallization was observed along c axis (single (0 0 2) diffraction peak) from substrate surface assigning the single crystalline Würtzite lattice for pure ZnO and AZO thin films. Although increasing Al concentration decreases the order of crystallization of as-grown films, annealing process increases the long range crystal order. The crystallite sizes vary between minimum 12.98 nm and maximum 20.79 nm for as-grown and annealed samples. The crystallite sizes decrease with increasing Al concentration but increase with increasing annealing temperature as general trend. The grain size and porosity of films change with annealing treatment. The smaller grains coalesce together to form larger grains for many films. However, a reverse behavior is seen for Al 2.23 ZnO and Al 12.30 ZnO samples. That is, Al concentration plays critical role as well as temperature on grain size. Low percent optical transmittance (T%) is observed due to higher Al

Effect of tellurium on machinability and mechanical property of CuAlMnZn shape memory alloy

International Nuclear Information System (INIS)

Liu Na; Li Zhou; Xu Genying; Feng Ze; Gong Shu; Zhu Lilong; Liang Shuquan

2011-01-01

Highlights: → A novel free-machining Cu-7.5Al-9.7Mn-3.4Zn-0.3Te (wt.%) shape memory alloy has been developed. → The size of dispersed particles with richer Te is 2-5 μm. → The CuAlMnZnTe alloy has good machinability which approached that of BZn15-24-1.5 due to the addition of Te. → Its shape memory property keeps the same as that of CuAlMnZn alloy with free Te. → The CuAlMnZn shape memory alloy with and without Te both have good ductile as annealed at 700 deg. C for 15 min. - Abstract: The microstructure transition, shape memory effect, machinability and mechanical property of the CuAlMnZn alloy with and without Te have been studied using X-ray diffraction analysis, chips observation and scanning electron microscopy (SEM), tensile strength test and differential scanning calorimeter (DSC), and semi-quantitative shape memory effect (SME) test. The particles with richer Te dispersedly distributed in grain interior and boundary with size of 2-5 μm. After the addition of Te, the CuAlMnZnTe alloy machinability has been effectively increased to approach that of BZn15-24-1.5 and its shape memory property remains the same as the one of CuAlMnZn alloy. The CuAlMnZn shape memory alloys with and without Te both have good ductility as annealed at 700 deg. C for 15 min.

Experimental and theoretical investigations on magnetic behavior of (Al,Co) co-doped ZnO nanoparticles.

Science.gov (United States)

Jayakumar, O D; Achary, S N; Sudakar, C; Naik, R; Salunke, H G; Rao, Rekha; Peng, X; Ahuja, R; Tyagi, A K

2010-08-01

We present the structural and magnetic properties of Zn(0.95-x)Co(0.05)Al(x)O (x = 0.0 to 0.1) nanoparticles, synthesized by a novel sol-gel route followed by pyrolysis. Powder X-ray diffraction data confirms the formation of a single phase wurtzite type ZnO structure for all the compositions. The Zn(0.95)Co(0.05)O nanoparticles show diamagnetic behavior at room temperature. However, when Al is co-doped with Co with x = 0.0 to 0.10 in Zn(0.95-x)Co(0.05)Al(x)O, a systematic increase in ferromagnetic moment is observed up to x = 0.07 at 300 K. Above x = 0.07 (e.g. for x = 0.10) a drastic decrease in ferromagnetic nature is observed which is concomitant with the segregation of poorly crystalline Al rich ZnO phase as evidenced from TEM studies. Theoretical studies using density functional calculations on Zn(0.95-x)Co(0.05)Al(x)O suggest that the partial occupancy of S2 states leads to an increased double exchange interaction favoring the ferromagnetic ground states. Such ferromagnetic interactions are favorable beyond a threshold limit. At a high level doping of Al, the exchange splitting is reduced, which suppresses the ferromagnetic ordering.

N2O Decomposition over Cu–Zn/γ–Al2O3 Catalysts

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Runhu Zhang

2016-12-01

Full Text Available Cu–Zn/γ–Al2O3 catalysts were prepared by the impregnation method. Catalytic activity was evaluated for N2O decomposition in a fixed bed reactor. The fresh and used catalysts were characterized by several techniques such as BET surface area, X-ray diffraction (XRD, and scanning electron microscopy (SEM. The Cu–Zn/γ–Al2O3 catalysts exhibit high activity and stability for N2O decomposition in mixtures simulating real gas from adipic acid production, containing N2O, O2, NO, CO2, and CO. Over the Cu–Zn/γ–Al2O3 catalysts, 100% of N2O conversion was obtained at about 601 °C at a gas hourly space velocity (GHSV of 7200 h−1. Cu–Zn/γ–Al2O3 catalysts also exhibited considerably good durability, and no obvious activity loss was observed in the 100 h stability test. The Cu–Zn/γ–Al2O3 catalysts are promising for the abatement of this powerful greenhouse gas in the chemical industry, particularly in adipic acid production.

Effect of Recrystallization and Natural Aging on Mechanical Properties of Al-Zn-Mg-Cu-Sc Alloys

International Nuclear Information System (INIS)

Yu, Min Kyu; Hong, Soon Hyung; Kwon, Oh Yeol; Lee, Yong Yeon

2015-01-01

In this study, the recrystallization volume fraction of the Al-Zn-Mg-Cu-Sc alloy after solid solution heat treatment varied with different temperatures (445℃ - 465℃). The highest elongation of the Al-Zn-Mg-Cu-Sc alloy was obtained at 465℃. Further, the hardness and strength of the solid solution heat treated Al-Zn-Mg-Cu-Sc alloy increased at room temperature due to G.P zone precipitates. The results confirmed that we can obtain advanced mechanical properties for the Al-Zn-Mg-Cu-Sc alloy from solid solution heat treatment and natural aging.

Origins of low resistivity in Al ion-implanted ZnO bulk single crystals

Science.gov (United States)

Oga, T.; Izawa, Y.; Kuriyama, K.; Kushida, K.; Kinomura, A.

2011-06-01

The origins of low resistivity in Al ion-implanted ZnO bulk single crystals are studied by combining Rutherford backscattering spectroscopy (RBS), nuclear reaction analysis (NRA), photoluminescence (PL), and Van der Pauw methods. The Al-ion implantation (peak concentration: 2.6 × 1020cm-3) into ZnO is performed using a multiple-step energy. The resistivity decreases from ˜104 Ω cm for un-implanted ZnO to 1.4 × 10-1 Ω cm for as-implanted, and reaches 6.0 × 10-4 Ω cm for samples annealed at 1000 °C. RBS and NRA measurements for as-implanted ZnO suggest the existence of the lattice displacement of Zn (Zni) and O (Oi), respectively. After annealing at 1000 °C, the Zni related defects remain and the Oi related defects disappear. The origin of the low resistivity in the as-implanted sample is attributed to the Zni (˜30 meV [Look et al., Phys. Rev. Lett. 82, 2552 (1999)]). In contrast, the origin of the low resistivity in the sample annealed at 1000 °C is assigned to both of the Zni related defects and the electrically activated Al donor. A new PL emission appears at around 3.32 eV after annealing at 1000 °C, suggesting electrically activated Al donors.

Microstructure and Mechanical Properties of Zn-Ni-Al2O3 Composite Coatings

Directory of Open Access Journals (Sweden)

Yang Bai

2018-05-01

Full Text Available Zn-Ni-Al2O3 composite coatings with different Ni contents were fabricated by low-pressure cold spray (LPCS technology. The effects of the Ni content on the microstructural and mechanical properties of the coatings were investigated. According to X-ray diffraction patterns, the composite coatings were primarily composed of metallic-phase Zn and Ni and ceramic-phase Al2O3. The energy-dispersive spectroscopy results show that the Al2O3 content of the composite coatings gradually decreased with increasing of Ni content. The cross-sectional morphology revealed thick, dense coatings with a wave-like stacking structure. The process of depositing Zn and Ni particles and Al2O3 particles by the LPCS method was examined, and the deposition mechanism was demonstrated to be mechanical interlocking. The bond strength, micro hardness and friction coefficient of the coatings did not obviously change when the Ni content varied. The presence of Al2O3 and Ni increased the wear resistance of the composite coatings, which was higher than that of pure Zn coatings, and the wear mechanism was abrasive and adhesive wear.

Surface modification of ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4} aiming to obtaining ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4}/SiO{sub 2} hybrid for use as a biosensor; Modificacao da superficie do ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4} visando a obtencao do hibrido ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4}/SiO{sub 2} para aplicacao como biossensor

Energy Technology Data Exchange (ETDEWEB)

Araujo, P.M.A.G.; Santos, P.T.A.; Costa, A.C.F.M., E-mail: pascally.guerra@gmail.com, E-mail: polyanaquimica@yahoo.com.br, E-mail: ana.costa@ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Junior, S.A.; Viana, R. S., E-mail: salvesjr@ufpe.br, E-mail: rodrigosilva.viana@yahoo.com.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

2017-01-15

This study aimed to investigate the influence of surface modification of ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4} nanoparticles for obtaining hybrid ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4}/SiO{sub 2} for application as a biosensor. Initially ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4} nanoparticles were synthesized by combustion reaction and, subsequently, their surfaces were modified with silane agent. The samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and excitation and emission spectroscopy. The results showed formation of ZnAl{sub 2}O{sub 4} as the major phase. By SEM, hard agglomerates, irregularly shaped in the form of plaques, with the presence of few irregular and variables pores were observed. The surface modification was confirmed by FTIR through the silanol and siloxane groups. The excitation and emission spectra revealed the presence of a broadband of ZnAl{sub 2} O{sub 4} matrix, and fine and intense transitions from europium ion arising from doping of non-stoichiometric ZnAl{sub 2}O{sub 4} with the europium. From the results of emission and excitation, it was observed that the luminescence of ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4}/SiO{sub 2} hybrid presented a small decrease in relation to the ZnAl{sub 1.9}Eu0.0{sub 5}O{sub 4} nanoparticles. This decrease was almost insignificant in relation to the benefits of silanization caused by the introduction of functional groups that promote combination of hybrid ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4}/SiO{sub 2} with biomolecules, being this promising for application as a biosensor used in the biomedical field for the diagnosis and treatment of diseases. (author)

Low Cycle Mechanical and Fatigue Properties of AlZnMgCu Alloy

Directory of Open Access Journals (Sweden)

Pysz S.

2016-03-01

Full Text Available The article presents the analysis of properties of the high-strength AlZnMgCu (abbr AlZn aluminium alloy and estimates possibilities of its application for responsible structures with reduced weight as an alternative to iron alloy castings. The aim of the conducted studies was to develop and select the best heat treatment regime for a 7xx casting alloy based on high-strength materials for plastic working from the 7xxx series. For analysis, wrought AlZnMgCu alloy (7075 was selected. Its potential of the estimated as-cast mechanical properties indicates a broad spectrum of possible applications for automotive parts and in the armaments industry. The resulting tensile and fatigue properties support the thesis adopted, while the design works further confirm these assumptions.

Evaluation of wrought Zn-Al alloys (1, 3, and 5 wt % Al) through mechanical and in vivo testing for stent applications.

Science.gov (United States)

Bowen, Patrick K; Seitz, Jan-Marten; Guillory, Roger J; Braykovich, Jacob P; Zhao, Shan; Goldman, Jeremy; Drelich, Jaroslaw W

2018-01-01

Special high grade zinc and wrought zinc-aluminum (Zn-Al) alloys containing up to 5.5 wt % Al were processed, characterized, and implanted in rats in search of a new family of alloys with possible applications as bioabsorbable endovascular stents. These materials retained roll-induced texture with an anisotropic distribution of the second-phase Al precipitates following hot-rolling, and changes in lattice parameters were observed with respect to Al content. Mechanical properties for the alloys fell roughly in line with strength (190-240 MPa yield strength; 220-300 MPa ultimate tensile strength) and elongation (15-30%) benchmarks, and favorable elastic ranges (0.19-0.27%) were observed. Intergranular corrosion was observed during residence of Zn-Al alloys in the murine aorta, suggesting a different corrosion mechanism than that of pure zinc. This mode of failure needs to be avoided for stent applications because the intergranular corrosion caused cracking and fragmentation of the implants, although the composition of corrosion products was roughly identical between non- and Al-containing materials. In spite of differences in corrosion mechanisms, the cross-sectional reduction of metals in murine aorta was nearly identical at 30-40% and 40-50% after 4.5 and 6 months, respectively, for pure Zn and Zn-Al alloys. Histopathological analysis and evaluation of arterial tissue compatibility around Zn-Al alloys failed to identify areas of necrosis, though both chronic and acute inflammatory indications were present. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 245-258, 2018. © 2017 Wiley Periodicals, Inc.

Study of structural and optical properties of ZnAlQ5 (zinc aluminum quinolate) organic phosphor for OLED applications

Science.gov (United States)

Nagpure, I. M.; Painuly, Deepshikha; Rabanal, Maria Eugenia

2016-05-01

The various composition of ZnAlQ5 such as Zn1.5A10.5Q5, Zn1Al1Q5, Zn0.5Al1.5Q5 organic phosphors were prepared via simple cost effective co-precipitation method. The FTIR, SEM, photoluminescence analysis of the prepared phosphors were reported. ZnQ2 and AlQ3 were also prepared by similar method and their properties were compared with different composition of ZnAlQ5. The structural elucidation in the form of stretching frequencies of chemical bonds of the prepared phosphor was carried out using Fourier Transform Infrared Spectroscopy (FTIR). The stretching frequency analysis confirms the formation of prepared phosphor materials. The SEM analysis shows the surface morphological behavior of prepared phosphor materials. Greenish photoluminescence were observed at 505 to 510 nm for the different composition of ZnAlQ5,in which Zn1.5Al0.5Q5 shows maximum luminescence intensity at 505 nm. PL emission of ZnQ2 was observed at 515 nm, while for AlQ3 at 520 nm. The blue shift of 10 nm was observed in Zn1.5A10.5Q5 due to modification of energy level due to presence of Zn2+ and Al3+. The enhancement in PL intensity was observed in Zn1.5A10.5Q5 compared to the other composition due to transfer of energy between Zn2+ and quinolate complex. Optical properties of the prepared materials were evaluated for possible applications in organic light emitting devices (OLED).

Corrosion resistance and protection mechanism of hot-dip Zn-Al-Mg alloy coated steel sheet under accelerated corrosion environment; Yoyu Zn-Al-Mg kei gokin mekki koban no sokushin fushoku kankyoka ni okeru taishokusei toi boshoku kiko

Energy Technology Data Exchange (ETDEWEB)

Komatsu, A.; Izutani, H.; Tsujimura, T.; Ando, A.; Kittaka, T. [NKK Corp., Tokyo (Japan)

2000-08-01

Corrosion behavior of hot-dip Zn-6%Al 0-3%Mg alloy coated steel sheets in cyclic corrosion test (CCT) has been investigated. The corrosion resistance was improved with increasing Mg content in the coating layer, and the highest corrosion resistance was observed at 3% Mg. In Zn-6%Al-3%Mg alloy coated steel sheet, the formations of zinc carbonate hydroxide and zinc oxide were suppressed for longer duration compared with Zn-0.2%Al and Zn-4.5%Al-0.l%Mg alloy coated steel sheets. As a result, zinc chloride hydroxide existed stable on the surface of the coating layer. From the polarization behaviors in 5% NaCl aqueous solution after CCT, it was found that the corrosion current density of Zn-6%At-3%Mg alloy coated steel sheet was much smaller than those of Zn-0.2%Al and Zn-4.5%Al-0.1%Mg alloy coated steel sheets. As zinc carbonate hydroxide and zinc oxide had poor adhesion to the coating layer and had porous structures, these corrosion products were considered to have little protective action for the coating layer. Therefore, it was concluded that Mg suppressed the formation of such nonprotective corrosion products. resulting in the remarkable improvement of corrosion resistance. (author)

Synthesis of highly conductive thin-walled Al-doped ZnO single-crystal microtubes by a solid state method

Science.gov (United States)

Hu, Shuopeng; Wang, Yue; Wang, Qiang; Xing, Cheng; Yan, Yinzhou; Jiang, Yijian

2018-06-01

ZnO has attracted considerable attention in fundamental studies and practical applications for the past decade due to its outstanding performance in gas sensing, photocatalytic degradation, light harvesting, UV-light emitting/lasing, etc. The large-sized thin-walled ZnO (TW-ZnO) microtube with stable and rich VZn-related acceptors grown by optical vapor supersaturated precipitation (OVSP) is a novel multifunctional optoelectronic material. Unfortunately, the OVSP cannot achieve doping due to the vapor growth process. To obtain doped TW-ZnO microtubes, a solid state method is introduced in this work to achieve thin-walled Al-doping ZnO (TW-ZnO:Al) microtubes with high electrical conductivity. The morphology and microstructures of ZnO:Al microtubes are similar to undoped ones. The Al3+ ions are confirmed to substitute Zn2+ sites and Zn(0/-1) vacancies in the lattice of ZnO by EDS, XRD, Raman and temperature-dependent photoluminescence analyses. The Al dopant acting as a donor level offers massive free electrons to increase the carrier concentrations. The resistivity of the ZnO:Al microtube is reduced down to ∼10-3 Ω·cm, which is one order of magnitude lower than that of the undoped microtube. The present work provides a simple way to achieve doped ZnO tubular components for potential device applications in optoelectronics.

Uniform distribution of TiCp in TiCp/Zn-Al composites prepared by XDTM

Institute of Scientific and Technical Information of China (English)

王香; 马旭梁; 李庆芬; 曾松岩

2002-01-01

The prefabricated Al/TiC alloy with high TiC particle content was prepared by XDTM process. The uniform distribution process of TiC particles in the stationary zinc melt was studied and analyzed using self-made experimental equipment, and the model of the uniform distribution process was built. The results show that zinc diffuses into the prepared Al/TiC alloy after it is placed in the zinc melt at temperatures below the melting point of aluminum, which leads to the decrease of the liquidus temperature of Al-Zn alloy in the surface layer of Al/TiC alloy. When the liquidus temperature of Al-Zn alloy is equal to or below the temperature of zinc melt, Al-Zn alloy melts and TiC particles drop with it from the Al/TiC alloy and then transfer into the zinc melt and finally distribute uniformly in it.

Superconducting properties of Zn and Al double-doped Mg1-x(Zn0.5Al0.5)xB2

DEFF Research Database (Denmark)

Xu, G.J.; Grivel, Jean-Claude; Abrahamsen, A.B.

2004-01-01

(XRD), ac susceptibility, magnetization and resistivity. The double doping leads to decreases in both the lattice parameters a and c, and the T-c decreases with increasing dopant content. A systematical comparison with Al doped- and Li, Al double doped MgB2 of structure, superconducting transition......A series of polycrystalline samples of Mg1-x(Zn0.5Al0.5)(x)B-2 (0less than or equal toxless than or equal to0.8) were prepared by solid state reaction method and their structure, superconducting transition temperature (T-c) and transport properties were investigated by means of X-ray diffraction...

Nanoparticles from Cu-Zn-Al shape memory alloys physically synthesized by ion milling deposition

Energy Technology Data Exchange (ETDEWEB)

Pavon, Luis Alberto Lopez [Universidad Autonoma de Nuevo Leon (UANL), Nuevo Leon (Mexico); Cuellara, Enrique Lopez; Castro, Alejandro Torres; Cruza, Azael Martinez de la [Universidad Autonoma de Nuevo Leon (CIIDIT/UANL), Nuevo Leon (Mexico). Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia; Ballesteros, Carmen [Universidad Carlos III de Madrid, Madrid (Spain). Departamento de Fisica; Araujo, Carlos Jose de [Universidade Federal de Campina Grande (UFCG), Campina Grande, PB (Brazil). Departamento de Engenharia Mecanica

2012-05-15

In this research, an ion milling equipment was used to elaborate nanoparticles from Cu-Zn-Al alloys with shape memory effect. Two different compositions were used, target A: 75.22Cu-17.12Zn-7.66Al at % with an Ms of -9 deg C and target B: 76.18Cu-15.84Zn-7.98Al with an Ms of 20 degree C. Nanoparticles were characterized by High Resolution Transmission Electron Microscopy, Electron Diffraction and Energy Dispersive X-ray Spectroscopy. The obtained nanoparticles showed a small dispersion, with a size range of 3.2-3.5 nm. Their crystal structure is in good agreement with the bulk martensitic structure of the targets. In this sense, results on morphology, composition and crystal structure have indicated that it is possible to produce nanoparticles of CuZnAl shape memory alloys with martensitic structure in a single process using Ion Milling. (author)

Nanoparticles from Cu-Zn-Al shape memory alloys physically synthesized by ion milling deposition

International Nuclear Information System (INIS)

Pavon, Luis Alberto Lopez; Cuellara, Enrique Lopez; Castro, Alejandro Torres; Cruza, Azael Martinez de la; Ballesteros, Carmen; Araujo, Carlos Jose de

2012-01-01

In this research, an ion milling equipment was used to elaborate nanoparticles from Cu-Zn-Al alloys with shape memory effect. Two different compositions were used, target A: 75.22Cu-17.12Zn-7.66Al at % with an Ms of -9 deg C and target B: 76.18Cu-15.84Zn-7.98Al with an Ms of 20 degree C. Nanoparticles were characterized by High Resolution Transmission Electron Microscopy, Electron Diffraction and Energy Dispersive X-ray Spectroscopy. The obtained nanoparticles showed a small dispersion, with a size range of 3.2-3.5 nm. Their crystal structure is in good agreement with the bulk martensitic structure of the targets. In this sense, results on morphology, composition and crystal structure have indicated that it is possible to produce nanoparticles of CuZnAl shape memory alloys with martensitic structure in a single process using Ion Milling. (author)

Preparation of ZnO-Al2O3 Particles in a Premixed Flame

DEFF Research Database (Denmark)

Jensen, Joakim Reimer; Johannessen, Tue; Wedel, Stig

2000-01-01

Zinc oxide (ZnO) and alumina (Al2O3) particles are synthesized by the combustion of their volatilized acetylacetonate precursors in a premixed air-methane flame reactor. The particles are characterized by XRD, transmission electron microscopy, scanning mobility particle sizing and by measurement...... temperature and a decreasing precursor vapour pressure. The combustion of precursor mixtures leads to composite particles consisting of zinc aluminate ZnAl2O4 intermixed with either ZnO or Al2O3 phases. The zinc aluminate particles are dendritic aggregates, resembling the alumina particles, and are evidently...... synthesized to the full extent allowed by the overall precursor composition. The addition of even small amounts of alumina to ZnO increases the specific surface area of the composites significantly, for e.g. zinc aluminate particles to approximately 150 m2/g. The gas-to-particle conversion is initiated...

Atomic layer deposition of Al-incorporated Zn(O,S) thin films with tunable electrical properties

International Nuclear Information System (INIS)

Park, Helen Hejin; Jayaraman, Ashwin; Heasley, Rachel; Yang, Chuanxi; Hartle, Lauren; Gordon, Roy G.; Mankad, Ravin; Haight, Richard; Gunawan, Oki; Mitzi, David B.

2014-01-01

Zinc oxysulfide, Zn(O,S), films grown by atomic layer deposition were incorporated with aluminum to adjust the carrier concentration. The electron carrier concentration increased up to one order of magnitude from 10 19 to 10 20 cm −3 with aluminum incorporation and sulfur content in the range of 0 ≤ S/(Zn+Al) ≤ 0.16. However, the carrier concentration decreased by five orders of magnitude from 10 19 to 10 14 cm −3 for S/(Zn+Al) = 0.34 and decreased even further when S/(Zn+Al) > 0.34. Such tunable electrical properties are potentially useful for graded buffer layers in thin-film photovoltaic applications

Design and fabrication of enhanced corrosion resistance Zn-Al layered double hydroxides films based anion-exchange mechanism on magnesium alloys

International Nuclear Information System (INIS)

Zhou, Meng; Yan, Luchun; Ling, Hao; Diao, Yupeng; Pang, Xiaolu; Wang, Yanlin; Gao, Kewei

2017-01-01

Highlights: • Zn-Al LDHs film loaded nitrate anions has been fabricated on a magnesium alloy substrate via a facile hydrothermal crystallization method. • The Zn-Al-Cl LDHs and Zn-Al-VO_x LDHs film were obtained based on anion-exchange mechanism. • The Zn-Al-Cl LDHs and Zn-Al-VO_x LDHs film could effectively protect magnesium alloy. - Abstract: Layered double hydroxides (LDHs) with brucite-like layer structure and the facile exchangeability of intercalated anions had attracted tremendous interest in many fields because of their great importance for both fundamental studies and practical applications. Herein zinc-aluminum layered double hydroxides (Zn-Al LDHs) films intercalated with nitrate anions on the magnesium alloy substrate were designed and fabricated via a facile hydrothermal crystallization method. In order to obtain better corrosion resistance, chloride and vanadate anions were intercalated into the LDHs interlayers via the anion-exchange reaction. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electronic microscopy (SEM) were used to examine structure, composition and morphology of the Zn-Al-NO_3 LDHs, Zn-Al-Cl LDHs and Zn-Al-VO_x LDHs films. The corrosion resistance of the Zn-Al LDHs with different anion films was estimated by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurement. EIS and polarization curves measurements revealed that the magnesium alloy could be effectively protected by the Zn-Al-Cl LDHs and Zn-Al-VO_x LDHs films due to the blocking effect of chloride anions and the control-release ability of vanadate anions.

Design and fabrication of enhanced corrosion resistance Zn-Al layered double hydroxides films based anion-exchange mechanism on magnesium alloys

Energy Technology Data Exchange (ETDEWEB)

Zhou, Meng; Yan, Luchun; Ling, Hao; Diao, Yupeng; Pang, Xiaolu; Wang, Yanlin; Gao, Kewei, E-mail: kwgao@yahoo.com

2017-05-15

Highlights: • Zn-Al LDHs film loaded nitrate anions has been fabricated on a magnesium alloy substrate via a facile hydrothermal crystallization method. • The Zn-Al-Cl LDHs and Zn-Al-VO{sub x} LDHs film were obtained based on anion-exchange mechanism. • The Zn-Al-Cl LDHs and Zn-Al-VO{sub x} LDHs film could effectively protect magnesium alloy. - Abstract: Layered double hydroxides (LDHs) with brucite-like layer structure and the facile exchangeability of intercalated anions had attracted tremendous interest in many fields because of their great importance for both fundamental studies and practical applications. Herein zinc-aluminum layered double hydroxides (Zn-Al LDHs) films intercalated with nitrate anions on the magnesium alloy substrate were designed and fabricated via a facile hydrothermal crystallization method. In order to obtain better corrosion resistance, chloride and vanadate anions were intercalated into the LDHs interlayers via the anion-exchange reaction. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electronic microscopy (SEM) were used to examine structure, composition and morphology of the Zn-Al-NO{sub 3} LDHs, Zn-Al-Cl LDHs and Zn-Al-VO{sub x} LDHs films. The corrosion resistance of the Zn-Al LDHs with different anion films was estimated by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurement. EIS and polarization curves measurements revealed that the magnesium alloy could be effectively protected by the Zn-Al-Cl LDHs and Zn-Al-VO{sub x} LDHs films due to the blocking effect of chloride anions and the control-release ability of vanadate anions.

Inverted Organic Solar Cells with Low-Temperature Al-Doped-ZnO Electron Transport Layer Processed from Aqueous Solution

Directory of Open Access Journals (Sweden)

Qianni Zhang

2018-01-01

Full Text Available The aqueous-based Zn-ammine complex solutions represent one of the most promising routes to obtain the ZnO electron transport layer (ETL at a low temperature in inverted organic solar cells (OSCs. However, to dope the ZnO film processed from the Zn-ammine complex solutions is difficult since the introduction of metal ions into the Zn-ammine complex is a nontrivial process as ammonium hydroxide tends to precipitate metal salts due to acid-base neutralization reactions. In this paper, we investigate the inverted OSCs with Al-doped-ZnO ETL made by immersion of metallic Al into the Zn-ammine precursor solution. The effects of ZnO layer with different immersion time of Al on film properties and solar cell performance have been studied. The results show that, with the Al-doped-ZnO ETL, an improvement of the device performance could be obtained compared with the device with the un-doped ZnO ETL. The improved device performance is attributed to the enhancement of charge carrier mobility leading to a decreased charge carrier recombination and improved charge collection efficiency. The fabricated thin film transistors with the same ZnO or AZO films confirm the improved electrical characteristics of the Al doped ZnO film.

Predictive calculation of phase formation in Al-rich Al-Zn-Mg-Cu-Sc-Zr alloys using a thermodynamic Mg-alloy database

International Nuclear Information System (INIS)

Groebner, J.; Rokhlin, L.L.; Dobatkina, T.V.; Schmid-Fetzer, R.

2007-01-01

Three series of Al-rich alloys in the system Al-Zn-Mg-Cu-Sc-Zr and the subsystems Al-Zn-Mg-Cu-Sc and Al-Zn-Mg-Sc were studied by thermodynamic calculations. Phase formation was compared with experimental data obtained by DTA and microstructural analysis. Calculated phase diagrams, phase amount charts and enthalpy charts together with non-equilibrium calculations under Scheil conditions reveal significant details of the complex phase formation. This enables consistent and correct interpretation of thermal analysis data. Especially the interpretation of liquidus temperature and primary phase is prone to be wrong without using this tool of computational thermodynamics. All data are predictions from a thermodynamic database developed for Mg-alloys and not a specialized Al-alloy database. That provides support for a reasonable application of this database for advanced Mg-alloys beyond the conventional composition ranges

Predictive calculation of phase formation in Al-rich Al-Zn-Mg-Cu-Sc-Zr alloys using a thermodynamic Mg-alloy database

Energy Technology Data Exchange (ETDEWEB)

Groebner, J. [Institute of Metallurgy, Clausthal University of Technology, Robert-Koch Strasse 42, D-38678 Clausthal-Zellerfeld (Germany); Rokhlin, L.L. [Baikov Institute of Metallurgy and Materials Science, Leninsky prosp. 49, 119991 GSP-1, Moscow (Russian Federation); Dobatkina, T.V. [Baikov Institute of Metallurgy and Materials Science, Leninsky prosp. 49, 119991 GSP-1, Moscow (Russian Federation); Schmid-Fetzer, R. [Institute of Metallurgy, Clausthal University of Technology, Robert-Koch Strasse 42, D-38678 Clausthal-Zellerfeld (Germany)]. E-mail: schmid-fetzer@tu-clausthal.de

2007-05-16

Three series of Al-rich alloys in the system Al-Zn-Mg-Cu-Sc-Zr and the subsystems Al-Zn-Mg-Cu-Sc and Al-Zn-Mg-Sc were studied by thermodynamic calculations. Phase formation was compared with experimental data obtained by DTA and microstructural analysis. Calculated phase diagrams, phase amount charts and enthalpy charts together with non-equilibrium calculations under Scheil conditions reveal significant details of the complex phase formation. This enables consistent and correct interpretation of thermal analysis data. Especially the interpretation of liquidus temperature and primary phase is prone to be wrong without using this tool of computational thermodynamics. All data are predictions from a thermodynamic database developed for Mg-alloys and not a specialized Al-alloy database. That provides support for a reasonable application of this database for advanced Mg-alloys beyond the conventional composition ranges.

Influence of Zn Interlayer on Interfacial Microstructure and Mechanical Properties of TIG Lap-Welded Mg/Al Joints

Science.gov (United States)

Gao, Qiong; Wang, Kehong

2016-03-01

This study explored 6061 Al alloy and AZ31B Mg alloy joined by TIG lap welding with Zn foils of varying thicknesses, with the additional Zn element being imported into the fusion zone to alloy the weld seam. The microstructures and chemical composition in the fusion zone near the Mg substrate were examined by SEM and EDS, and tensile shear strength tests were conducted to investigate the mechanical properties of the Al/Mg joints, as well as the fracture surfaces, and phase compositions. The results revealed that the introduction of an appropriate amount of Zn transition layer improves the microstructure of Mg/Al joints and effectively reduces the formation of Mg-Al intermetallic compounds (IMCs). The most common IMCs in the fusion zone near the Mg substrate were Mg-Zn and Mg-Al-Zn IMCs. The type and distribution of IMCs generated in the weld zone differed according to Zn additions; Zn interlayer thickness of 0.4 mm improved the sample's mechanical properties considerably compared to thicknesses of less than 0.4 mm; however, any further increase in Zn interlayer thickness of above 0.4 mm caused mechanical properties to deteriorate.

Viscosity of Industrially Important Zn-Al Alloys Part II: Alloys with Higher Contents of Al and Si

Science.gov (United States)

Nunes, V. M. B.; Queirós, C. S. G. P.; Lourenço, M. J. V.; Santos, F. J. V.; Nieto de Castro, C. A.

2018-05-01

The viscosity of Zn-Al alloys melts, with industrial interest, was measured for temperatures between 693 K and 915 K, with an oscillating cup viscometer, and estimated expanded uncertainties between 3 and 5 %, depending on the alloy. The influence of minor components, such as Si, Mg and Ce + La, on the viscosity of the alloys is discussed. An increase in the amount of Mg triggers complex melt/solidification processes while the addition of Ce and La renders alloys viscosity almost temperature independent. Furthermore, increases in Al and Si contents decrease melts viscosity and lead to an Arrhenius type behavior. This paper complements a previous study describing the viscosity of Zn-Al alloys with quasi-eutectic compositions.

Role of the preliminary heat treatment in anisothermic eutectoid change of the cast iron

Directory of Open Access Journals (Sweden)

T. Szykowny

2011-07-01

Full Text Available Preliminary heat treatment, preceding continuous cooling of the iron casting, assumed in the research, complies with the applied in prac- tice single normalization, double normalization or normalization with slow cooling. In each of these cases continuous cast iron cooling has been begun from the same temperature 925°C. CCT diagrams have been made with use of metallographic method. The mechanism, kinet- ics and the final structure of eutectoid change of the cast iron after such treatment have been traced.

Detecting the Extent of Eutectoid Transformation in U-10Mo

International Nuclear Information System (INIS)

Devaraj, Arun; Jana, Saumyadeep; McInnis, Colleen A.; Lombardo, Nicholas J.; Joshi, Vineet V.; Sweet, Lucas E.; Manandhar, Sandeep; Lavender, Curt A.

2016-01-01

During eutectoid transformation of U-10Mo alloy, uniform metastable ? UMo phase is expected to transform to a mixture of ?-U and ?'-U_2Mo phase. The presence of transformation products in final U-10Mo fuel, especially the ? phase is considered detrimental for fuel irradiation performance, so it is critical to accurately evaluate the extent of transformation in the final U-10Mo alloy. This phase transformation can cause a volume change that induces a density change in final alloy. To understand this density and volume change, we developed a theoretical model to calculate the volume expansion and resultant density change of U-10Mo alloy as a function of the extent of eutectoid transformation. Based on the theoretically calculated density change for 0 to 100% transformation, we conclude that an experimental density measurement system will be challenging to employ to reliably detect and quantify the extent of transformation. Subsequently, to assess the ability of various methods to detect the transformation in U-10Mo, we annealed U-10Mo alloy samples at 500°C for various times to achieve in low, medium, and high extent of transformation. After the heat treatment at 500°C, the samples were metallographically polished and subjected to optical microscopy and x-ray diffraction (XRD) methods. Based on our assessment, optical microscopy and image processing can be used to determine the transformed area fraction, which can then be correlated with the ? phase volume fraction measured by XRD analysis. XRD analysis of U-10Mo aged at 500°C detected only ? phase and no ?' was detected. To further validate the XRD results, atom probe tomography (APT) was used to understand the composition of transformed regions in U-10Mo alloys aged at 500°C for 10 hours. Based on the APT results, the lamellar transformation product was found to comprise ? phase with close to 0 at% Mo and ? phase with 28-32 at% Mo, and the Mo concentration was highest at the ?/? interface.

Hydrothermal synthesis and characterization of hybrid Al/ZnO-GO composite for significant photodegrdation of dyes

Energy Technology Data Exchange (ETDEWEB)

Lellala, Kashinath; Namratha, K.; Byrappa, K., E-mail: kashinathlellala@gmail.com, E-mail: kbyrappa@gmail.com [Centre for Materials Science and Technology, University of Mysore, Vijnana Bhavan, P.B.No.21, Manasagangothri, Mysore - 570006, India. (India); Sudhakar, K. [Lal Bhadur College, S.V.N. Road, Mulugu X-road, Kakatiya University, Warangal-560001, India. (India)

2016-05-06

In the present work, undoped and doped Aluminum/Zinc Oxide - graphene oxide (Al/ZnO-GO) nanocomposite have been successfully synthesized by hydrothermal method from zinc acetate and aluminum nitrate solutions without using of any surfactant/stabilizing agents. The results show that the composites of GO nanosheets are decorated densely by Al/ZnO nanoparticles, which displays a good morphology and blend between GO and Al/ZnO. Hybrid composites exhibit an enhanced photocatalytic performance in reduction of dyes under UV-Vis radiation better than bare ZnO-GO and GO for methylene blue dye. The hydrothermal method leads to particles with a higher crystalline due to ambient temperature of the reaction and autogenously pressure conditions, which alters the phases and crystallizations of the nanocomposite. The optical band gap is narrowed to lower energy values due to controlled addition of aluminum and GO in the composite. The improved optical property in Al-doped ZnO flower decorated on GO can be attributed to the decrease in oxygen deficiency after Al doping. XRD, FTIR, UV-Vis spectroscopy, Raman, and Field Emission Scanning Electron Microscopy characterized the effects of Al doping on the structural characteristics and optical properties on the ZnO-GO.

Atomic layer deposition of Al-incorporated Zn(O,S) thin films with tunable electrical properties

Energy Technology Data Exchange (ETDEWEB)

Park, Helen Hejin; Jayaraman, Ashwin; Heasley, Rachel; Yang, Chuanxi; Hartle, Lauren; Gordon, Roy G., E-mail: gordon@chemistry.harvard.edu [Harvard University, Cambridge, Massachusetts 02138 (United States); Mankad, Ravin; Haight, Richard; Gunawan, Oki [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Mitzi, David B. [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Duke University, Durham, North Carolina 27708 (United States)

2014-11-17

Zinc oxysulfide, Zn(O,S), films grown by atomic layer deposition were incorporated with aluminum to adjust the carrier concentration. The electron carrier concentration increased up to one order of magnitude from 10{sup 19} to 10{sup 20} cm{sup −3} with aluminum incorporation and sulfur content in the range of 0 ≤ S/(Zn+Al) ≤ 0.16. However, the carrier concentration decreased by five orders of magnitude from 10{sup 19} to 10{sup 14} cm{sup −3} for S/(Zn+Al) = 0.34 and decreased even further when S/(Zn+Al) > 0.34. Such tunable electrical properties are potentially useful for graded buffer layers in thin-film photovoltaic applications.

Grain boundary imaging, gallium diffusion and the fracture behavior of Al-Zn Alloy - An in situ study

CERN Document Server

Tsai, W L; Chen, C H; Chang, L W; Je, J H; Lin, H M; Margaritondo, G

2003-01-01

Phase contrast radiology using unmonochromatic synchrotron X-ray successfully imaged the grain boundaries of Al and AlZn alloy without contrast agent. Combining the high penetration of X-ray and the possibility of 3D reconstruction by tomorgraphy or stereography method, this approach can be very used for nondestructive characterization of polycrystalline materials. By examine the images with 3D perspective, we were able locate the observed void-like defects which lies exclusively on the grain boundary and identify their origin from last stage of the rolling process. We studied the Ga Liquid metal diffusion in the AlZn alloy, under different temperature and stress conditions. High resolution images, approx 2 mu m, of Ga liquid metal diffusion in AlZn were obtained in real time and diffusion paths alone grain boundaries and surfaces were clearly identified. Embrittled AlZn responses to the tensile stress and fractures in a drastic different manner than the pure AlZn. These results, although very much expected f...

Corrosion resistance of Zn-Al layered double hydroxide/poly(lactic acid) composite coating on magnesium alloy AZ31

Science.gov (United States)

Zeng, Rong-Chang; Li, Xiao-Ting; Liu, Zhen-Guo; Zhang, Fen; Li, Shuo-Qi; Cui, Hong-Zhi

2015-12-01

A Zn-Al layered double hydroxide (ZnAl-LDH) coating consisted of uniform hexagonal nano-plates was firstly synthesized by co-precipitation and hydrothermal treatment on the AZ31 alloy, and then a poly(lactic acid) (PLA) coating was sealed on the top layer of the ZnAl-LDH coating using vacuum freeze-drying. The characteristics of the ZnAl-LDH/PLA composite coatings were investigated by means of XRD, SEM, FTIR and EDS. The corrosion resistance of the coatings was assessed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the ZnAl-LDH coating contained a compact inner layer and a porous outer layer, and the PLA coating with a strong adhesion to the porous outer layer can prolong the service life of the ZnAl-LDH coating. The excellent corrosion resistance of this composite coating can be attributable to its barrier function, ion-exchange and self-healing ability.

Applications of ZnO:Al deposited by RF sputtering to InN low-cost technology

Energy Technology Data Exchange (ETDEWEB)

Fernandez, S. [Departamento de Energias Renovables, Energia Solar Fotovoltaica, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Madrid (Spain); Naranjo, F.B.; Valdueza-Felip, S. [Grupo de Ingenieria Fotonica, Departamento de Electronica, Escuela Politecnica Superior, Universidad de Alcala Campus Universitario, Madrid (Spain); Abril, O. de [ISOM y Departamento de Fisica Aplicada, Escuela Tecnica Superior de Ingenieros de Telecomunicacion, Universidad Politenica de Madrid (Spain)

2010-07-15

InN/ZnO:Al heterostructures deposited at low temperature on different substrates by radio-frequency sputtering were studied. Using ZnO:Al as buffer layer, an improvement in the InN structural properties was achieved. Evaluating ZnO:Al as contact on InN, an Ohmic behaviour for the as-deposited layer on InN was achieved. A specific contact resistance of 2 {omega} cm{sup 2} was measured without any post-deposition treatment. These properties could result very promising for optoelectronic device applications. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Investigation of thermal, mechanical and magnetic behaviors of the Cu-11%Al alloy with Ag and Mn additions

International Nuclear Information System (INIS)

Silva, R.A.G.; Paganotti, A.; Gama, S.; Adorno, A.T.; Carvalho, T.M.; Santos, C.M.A.

2013-01-01

The investigation of thermal, mechanical and magnetic behaviors of the Cu-11%Al, Cu-11%Al-3%Ag, Cu-11%Al-10%Mn and Cu-11%Al-10%Mn-3%Ag alloys was made using microhardness measurements, differential scanning calorimetry, X-ray diffractometry, scanning electron microscopy, energy dispersion X-ray spectroscopy and magnetic moment change with applied field measurement. The results indicated that the Mn addition changes the phase stability range, the microhardness values and makes undetectable the eutectoid reaction in annealed Cu-11%Al and Cu-11%Al-3%Ag alloys while the presence of Ag does not modify the phase transformation sequence neither microhardness values of the annealed Cu-11%Al and Cu-11%Al-10%Mn alloys, but it increases the magnetic moment of this latter at about 2.7 times and decreases the rates of eutectoid and peritectoid reactions of the former. - Highlights: ► The microstructure of Cu-Al alloy is modified in the Ag presence. ► (α + γ) phase is stabilized down to room temperature when Ag is added to Cu-Al alloy. ► Ag-rich phase modifies the magnetic characteristics of Cu–Al–Mn alloy.

Hardness and microstructure of Al-10.0 wt% Zn-4.0 wt% Mg alloy

International Nuclear Information System (INIS)

Iqbal, M.; Shaikh, M.A.; Ahmad, W.; Ali, K.L.

1996-01-01

Al-Zn-Mg alloys are widely used in industries as these have excellent physical and mechanical properties. However some aspects of the effect of heat treatment on these alloys are not yet clear. In order to understand the precipitation phenomena in these alloys, microstructure of a locally prepared alloy Al-10.0 wt% Zn-4.0 wt% Mg heat treated under different conditions has been examined in scanning electron microscope/electron probe micro analyser. Precipitates MgZn/sub 2/, MgZn/sub 4/ and Mg/sub 2/Zn/sub 11/ have been observed and these are caused by heat treatment. Correlation between these precipitates and Vickers's hardness has also been studied. In the present paper results of this investigation have been presented and discussed. (author)

Band Offset Measurements in Atomic-Layer-Deposited Al2O3/Zn0.8Al0.2O Heterojunction Studied by X-ray Photoelectron Spectroscopy.

Science.gov (United States)

Yan, Baojun; Liu, Shulin; Heng, Yuekun; Yang, Yuzhen; Yu, Yang; Wen, Kaile

2017-12-01

Pure aluminum oxide (Al 2 O 3 ) and zinc aluminum oxide (Zn x Al 1-x O) thin films were deposited by atomic layer deposition (ALD). The microstructure and optical band gaps (E g ) of the Zn x Al 1-x O (0.2 ≤ x ≤ 1) films were studied by X-ray diffractometer and Tauc method. The band offsets and alignment of atomic-layer-deposited Al 2 O 3 /Zn 0.8 Al 0.2 O heterojunction were investigated in detail using charge-corrected X-ray photoelectron spectroscopy. In this work, different methodologies were adopted to recover the actual position of the core levels in insulator materials which were easily affected by differential charging phenomena. Valence band offset (ΔE V ) and conduction band offset (ΔE C ) for the interface of the Al 2 O 3 /Zn 0.8 Al 0.2 O heterojunction have been constructed. An accurate value of ΔE V  = 0.82 ± 0.12 eV was obtained from various combinations of core levels of heterojunction with varied Al 2 O 3 thickness. Given the experimental E g of 6.8 eV for Al 2 O 3 and 5.29 eV for Zn 0.8 Al 0.2 O, a type-I heterojunction with a ΔE C of 0.69 ± 0.12 eV was found. The precise determination of the band alignment of Al 2 O 3 /Zn 0.8 Al 0.2 O heterojunction is of particular importance for gaining insight to the design of various electronic devices based on such heterointerface.

Role of vacancy defects in Al doped ZnO thin films for optoelectronic devices

Science.gov (United States)

Rotella, H.; Mazel, Y.; Brochen, S.; Valla, A.; Pautrat, A.; Licitra, C.; Rochat, N.; Sabbione, C.; Rodriguez, G.; Nolot, E.

2017-12-01

We report on the electrical, optical and photoluminescence properties of industry-ready Al doped ZnO thin films grown by physical vapor deposition, and their evolution after annealing under vacuum. Doping ZnO with Al atoms increases the carrier density but also favors the formation of Zn vacancies, thereby inducing a saturation of the conductivity mechanism at high aluminum content. The electrical and optical properties of these thin layered materials are both improved by annealing process which creates oxygen vacancies that releases charge carriers thus improving the conductivity. This study underlines the effect of the formation of extrinsic and intrinsic defects in Al doped ZnO compound during the fabrication process. The quality and the optoelectronic response of the produced films are increased (up to 1.52 mΩ \\cdotcm and 3.73 eV) and consistent with the industrial device requirements.

The Effect of Zn-Al-Hydrotalcites Composited with Calcium Stearate and β-Diketone on the Thermal Stability of PVC

Directory of Open Access Journals (Sweden)

Runjuan Wen

2011-03-01

Full Text Available A clean-route synthesis of Zn-Al-hydrotalcites (Zn-Al-LDHs using zinc oxide and sodium aluminate solution has been developed. The as-obtained materials were characterized by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR, and scanning electron microscopy (SEM. The effects of metal ions at different molar ratios on the performance of hydrotalcites were discussed. The results showed that the Zn-Al-hydrotalcites can be successfully synthesized at three different Zn/Al ratios of 3:1, 2:1 and 1:1. Thermal aging tests of polyvinyl chloride (PVC mixed with Zn-Al-LDHs, calcium stearate (CaSt2 and β-diketone were carried out in a thermal aging test box by observing the color change. The results showed that Zn-Al-LDHs can not only enhance the stability of PVC significantly due to the improved capacity of HCl-adsorption but also increase the initial stability and ensure good-initial coloring due to the presence of the Zn element. The effects of various amounts of Zn-Al-LDHs, CaSt2 and β-diketone on the thermal stability of PVC were discussed. The optimum composition was determined to be 0.1 g Zn-Al-LDHs, 0.15 g CaSt2 and 0.25 g β-diketone in 5 g PVC.

Low-Lying Electronic States of AlZn Calculated by MRCI+Q Method

Science.gov (United States)

Zhang, Shudong; Wang, Mingxu; Wang, Zifan; Hu, Kun; Dong, Jingping

2017-07-01

Some low-lying electronic states of AlZn have been studied by the ab initio calculation method of multireference configuration interaction (MRCI). The complete potential energy curves (PECs) of the three lowest doublet states (X2Π, A2Σ+, and B2Π) and the two lowest quartet states (a4Σ- and b4Π) are computed in the range of R = 0.1-0.9 nm and these states are correlated to three dissociation limits, X2Π and A2Σ+ to Zn(4s2,1S) + Al(3s23p1,2P), a4Σ- and b4Π to Zn(4s2,1S) + Al(3s13p2,4P), and B2Π to Zn(4s14p1,3P) + Al(3s23p1,2P). The calculated PECs indicate that the A2Σ+ state has a very shallow potential well and the other states show significant binding-state characteristics. The equilibrium internuclear distances Re, dissociation energies De, and term energies Te for the electronic excited states were obtained. All the possible vibrational levels, rotational constants, and spectral constants for the four bound states were computed by solving the radial Schrödinger equation of nuclear motion with the Level8.0 program provided by Le Roy.

Analysis of SAW properties in ZnO/AlxGa1-xN/c-Al2O3 structures.

Science.gov (United States)

Chen, Ying; Emanetoglu, Nuri William; Saraf, Gaurav; Wu, Pan; Lu, Yicheng; Parekh, Aniruddh; Merai, Vinod; Udovich, Eric; Lu, Dong; Lee, Dong S; Armour, Eric A; Pophristic, Milan

2005-07-01

Piezoelectric thin films on high acoustic velocity nonpiezoelectric substrates, such as ZnO, AlN, or GaN deposited on diamond or sapphire substrates, are attractive for high frequency and low-loss surface acoustic wave devices. In this work, ZnO films are deposited on AlxGa1-xN/c-Al2O3 (0 structure provides several advantages, including higher order wave modes with higher velocity and larger electromechanical coupling coefficient (K2). The surface acoustic wave (SAW) velocities and coupling coefficients of the ZnO/AlxGa1-xN/c-Al2O3 structure are tailored as a function of the Al mole percentage in AlxGa1-xN films, and as a function of the ZnO (h1) to AlxGa1-xN (h2) thickness ratio. It is found that a wide thickness-frequency product (hf) region in which coupling is close to its maximum value, K(2)max, can be obtained. The K(2)max of the second order wave mode (h1 = h2) is estimated to be 4.3% for ZnO/GaN/c-Al2O3, and 3.8% for ZnO/AlN/c-Al2O3. The bandwidth of second and third order wave modes, in which the coupling coefficient is within +/- 0.3% of K(2)max, is calculated to be 820 hf for ZnO/GaN/c-Al2O3, and 3620 hf for ZnO/AlN/c-Al2O3. Thus, the hf region in which the coupling coefficient is close to the maximum value broadens with increasing Al content, while K(2)max decreases slightly. When the thickness ratio of AlN to ZnO increases, the K(2)max and hf bandwidth of the second and third higher wave modes increases. The SAW test devices are fabricated and tested. The theoretical and experimental results of velocity dispersion in the ZnO/AlxGa1-xN/c-Al2O3 structures are found to be well matched.

On the transparent conducting oxide Al doped ZnO: First Principles and Boltzmann equations study

Energy Technology Data Exchange (ETDEWEB)

Slassi, A. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco); Naji, S. [LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco); Department of Physics, Faculty of Science, Ibb University, Ibb (Yemen); Benyoussef, A. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco); Hamedoun, M., E-mail: hamedoun@hotmail.com [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); El Kenz, A. [LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco)

2014-08-25

Highlights: • The incorporation of Al in ZnO increases the optical band edge absorption. • Incorporated Al creates shallow donor states of Al-3s around Fermi level. • Transmittance decreases in the visible and IR regions, while it increases in the UV region. • Electrical conductivity increases and reaches almost the saturation for high concentration of Al. - Abstract: We report, in this work, a theoretical study on the electronic, optical and electrical properties of pure and Al doped ZnO with different concentrations. In fact, we investigate these properties using both First Principles calculations within TB-mBJ approximation and Boltzmann equations under the constant relaxation time approximation for charge carriers. It is found out that, the calculated lattice parameters and the optical band gap of pure ZnO are close to the experimental values and in a good agreement with the other theoretical studies. It is also observed that, the incorporations of Al in ZnO increase the optical band edge absorption which leads to a blue shift and no deep impurities levels are induced in the band gap as well. More precisely, these incorporations create shallow donor states around Fermi level in the conduction band minimum from mainly Al-3s orbital. Beside this, it is found that, the transmittance is decreased in the visible and IR regions, while it is significantly improved in UV region. Finally, our calculations show that the electrical conductivity is enhanced as a result of Al doping and it reaches almost the saturation for high concentration of Al. These features make Al doped ZnO a transparent conducting electrode for optoelectronic device applications.

Theoretical study of ZnO adsorption and bonding on Al2O3 (0001) surface

Institute of Scientific and Technical Information of China (English)

LI Yanrong; YANG Chun; XUE Weidong; LI Jinshan; LIU Yonghua

2004-01-01

ZnO adsorption on sapphire (0001) surface is theoretically calculated by using a plane wave ultrasoft pseudo-potential method based on ab initio molecular dynamics. The results reveal that the surface relaxation in the first layer Al-O is reduced, even eliminated after the surface adsorption of ZnO, and the chemical bonding energy is 434.3(±38.6) kJ·mol-1. The chemical bond of ZnO (0.185 ± 0.01 nm) has a 30° angle away from the adjacent Al-O bond, and the stable chemical adsorption position of the Zn is deflected from the surface O-hexagonal symmetry with an angle of about 30°. The analysis of the atomic populations, density of state and bonding electronic density before and after the adsorption indicates that the chemical bond formed by the O2- of the ZnO and the surface Al3+ has a strong ionic bonding characteristic, while the chemical bond formed by the Zn2+ and the surface O2- has an obvious covalent characteristic, which comes mainly from the hybridization of the Zn 4s and the O 2p and partially from that of the Zn 3d and the O 2p.

Z-scan measurement for nonlinear absorption property of rGO/ZnO:Al thin film

Science.gov (United States)

Sreeja, V. G.; Anila, E. I.

2018-04-01

We report the fabrication of reduced graphene oxide integrated aluminium doped zinc oxide (rGO/ZnO:Al) composite thin film on a glass substrate by spin coating technique. The effect of rGO on structural and linear optical properties of rGO/ZnO:Al composite thin film was explored with the help of X-Ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-Vis absorption spectroscopy. Structural studies reveals that the composite film has hexagonal wurtzite structure with a strong bonding between rGO and ZnO:Al material. The band gap energy of ZnO:Al thin film was red shifted by the addition of rGO. The Nonlinear absorption property was investigated by open aperture Z-scan technique by using Q switched Nd-YAG laser at 532nm. The Z-scan results showed that the composite film demonstrates reverse saturable absorption property with a nonlinear absorption coefficient, β, of 12.75×10-7m/w. The results showed that investigated rGO/ZnO:Al thin film is a promising material suitable for the applications in absorbing type optical devices such as optical limiters, optical switches and protection of the optical sensors in the field of nonlinear optics.

Effect of Heat Treatment on the Microstructure and Wear Properties of Al-Zn-Mg-Cu/In-Situ Al-9Si-SiCp/Pure Al Composite by Powder Metallurgy

Science.gov (United States)

Yu, Byung Chul; Bae, Ki-Chang; Jung, Je Ki; Kim, Yong-Hwan; Park, Yong Ho

2018-03-01

This study examined the effects of heat treatment on the microstructure and wear properties of Al-Zn-Mg-Cu/in-situ Al-9Si-SiCp/pure Al composites. Pure Al powder was used to increase densification but it resulted in heterogeneous precipitation as well as differences in hardness among the grains. Heat treatment was conducted to solve this problem. The heat treatment process consisted of three stages: solution treatment, quenching, and aging treatment. After the solution treatment, the main dissolved phases were η'(Mg4Zn7), η(MgZn2), and Al2Cu phase. An aging treatment was conducted over the temperature range, 100-240 °C, for various times. The GP zone and η'(Mg4Zn7) phase precipitated at a low aging temperature of 100-160 °C, whereas the η(MgZn2) phase precipitated at a high aging temperature of 200-240 °C. The hardness of the sample aged at 100-160 °C was higher than that aged at 200-240 °C. The wear test was conducted under various linear speeds with a load of 100 N. The aged composite showed a lower wear rate than that of the as-sintered composite under all conditions. As the linear speed was increased to 1.0 m/s, the predominant wear behavior changed from abrasive to adhesive wear in all composites.

Effect of Heat Treatment on the Microstructure and Wear Properties of Al-Zn-Mg-Cu/In-Situ Al-9Si-SiCp/Pure Al Composite by Powder Metallurgy

Science.gov (United States)

Yu, Byung Chul; Bae, Ki-Chang; Jung, Je Ki; Kim, Yong-Hwan; Park, Yong Ho

2018-05-01

This study examined the effects of heat treatment on the microstructure and wear properties of Al-Zn-Mg-Cu/in-situ Al-9Si-SiCp/pure Al composites. Pure Al powder was used to increase densification but it resulted in heterogeneous precipitation as well as differences in hardness among the grains. Heat treatment was conducted to solve this problem. The heat treatment process consisted of three stages: solution treatment, quenching, and aging treatment. After the solution treatment, the main dissolved phases were η'(Mg4Zn7), η(MgZn2), and Al2Cu phase. An aging treatment was conducted over the temperature range, 100-240 °C, for various times. The GP zone and η'(Mg4Zn7) phase precipitated at a low aging temperature of 100-160 °C, whereas the η(MgZn2) phase precipitated at a high aging temperature of 200-240 °C. The hardness of the sample aged at 100-160 °C was higher than that aged at 200-240 °C. The wear test was conducted under various linear speeds with a load of 100 N. The aged composite showed a lower wear rate than that of the as-sintered composite under all conditions. As the linear speed was increased to 1.0 m/s, the predominant wear behavior changed from abrasive to adhesive wear in all composites.

Study of structural and optical properties of ZnAlQ{sub 5} (zinc aluminum quinolate) organic phosphor for OLED applications

Energy Technology Data Exchange (ETDEWEB)

Nagpure, I. M., E-mail: indrajitnagpure@gmail.com; Painuly, Deepshikha [Physics, Department of Sciences and Humanities, National Institute of Technology,Uttarakhand-246174 (India); Rabanal, Maria Eugenia [Department of Materials Science and Engineering and Chemical Engineering,University Carlos III of Madrid, Avd. Universidad 30, 28911 Leganes, Madrid (Spain)

2016-05-06

The various composition of ZnAlQ{sub 5} such as Zn{sub 1.5}A{sub 10.5}Q{sub 5}, Zn{sub 1}Al{sub 1}Q{sub 5}, Zn{sub 0.5}Al{sub 1.5}Q{sub 5} organic phosphors were prepared via simple cost effective co-precipitation method. The FTIR, SEM, photoluminescence analysis of the prepared phosphors were reported. ZnQ{sub 2} and AlQ{sub 3} were also prepared by similar method and their properties were compared with different composition of ZnAlQ{sub 5}. The structural elucidation in the form of stretching frequencies of chemical bonds of the prepared phosphor was carried out using Fourier Transform Infrared Spectroscopy (FTIR). The stretching frequency analysis confirms the formation of prepared phosphor materials. The SEM analysis shows the surface morphological behavior of prepared phosphor materials. Greenish photoluminescence were observed at 505 to 510 nm for the different composition of ZnAlQ{sub 5},in which Zn{sub 1.5}Al{sub 0.5}Q{sub 5} shows maximum luminescence intensity at 505 nm. PL emission of ZnQ{sub 2} was observed at 515 nm, while for AlQ{sub 3} at 520 nm. The blue shift of 10 nm was observed in Zn{sub 1.5}A{sub 10.5}Q{sub 5} due to modification of energy level due to presence of Zn{sup 2+} and Al{sup 3+}. The enhancement in PL intensity was observed in Zn{sub 1.5}A{sub 10.5}Q{sub 5} compared to the other composition due to transfer of energy between Zn{sup 2+} and quinolate complex. Optical properties of the prepared materials were evaluated for possible applications in organic light emitting devices (OLED).

Expanding Thermal Plasma Chemical Vapour Deposition of ZnO:Al Layers for CIGS Solar Cells

Directory of Open Access Journals (Sweden)

K. Sharma

2014-01-01

Full Text Available Aluminium-doped zinc oxide (ZnO:Al grown by expanding thermal plasma chemical vapour deposition (ETP-CVD has demonstrated excellent electrical and optical properties, which make it an attractive candidate as a transparent conductive oxide for photovoltaic applications. However, when depositing ZnO:Al on CIGS solar cell stacks, one should be aware that high substrate temperature processing (i.e., >200°C can damage the crucial underlying layers/interfaces (such as CIGS/CdS and CdS/i-ZnO. In this paper, the potential of adopting ETP-CVD ZnO:Al in CIGS solar cells is assessed: the effect of substrate temperature during film deposition on both the electrical properties of the ZnO:Al and the eventual performance of the CIGS solar cells was investigated. For ZnO:Al films grown using the high thermal budget (HTB condition, lower resistivities, ρ, were achievable (~5 × 10−4 Ω·cm than those grown using the low thermal budget (LTB conditions (~2 × 10−3 Ω·cm, whereas higher CIGS conversion efficiencies were obtained for the LTB condition (up to 10.9% than for the HTB condition (up to 9.0%. Whereas such temperature-dependence of CIGS device parameters has previously been linked with chemical migration between individual layers, we demonstrate that in this case it is primarily attributed to the prevalence of shunt currents.

Electrical Crystallization Mechanism and Interface Characteristics of Nano wire Zn O/Al Structures Fabricated by the Solution Method

International Nuclear Information System (INIS)

Tseng, Y.W.; Hung, F.Y.; Lui, T.Sh.; Chen, Y.T.; Xiao, R.S.; Chen, K.J.

2012-01-01

Both solution nano wire Zn O and sputtered Al thin film on SiO 2 as the wire-film structure and the Al film were a conductive channel for electrical-induced crystallization (EIC). Direct current (DC) raised the temperature of the Al film and improved the crystallization of the nano structure. The effects of EIC not only induced Al atomic interface diffusion, but also doped Al on the roots of Zn O wires to form aluminum doped zinc oxide (AZO)/Zn O wires. The Al doping concentration and the distance of the Zn O wire increased with increasing the electrical duration. Also, the electrical current-induced temperature was ∼211 degree C (solid-state doped process) and so could be applied to low-temperature optoelectronic devices.

Solution derived ZnO:Al films with low resistivity

International Nuclear Information System (INIS)

Schellens, K.; Capon, B.; De Dobbelaere, C.; Detavernier, C.; Hardy, A.; Van Bael, M.K.

2012-01-01

ZnO:Al thin films were prepared via chemical solution deposition, using 2-butoxyethanol as an alternative for 2-methoxyethanol, which is more commonly used, but acutely toxic. The precursor solutions can be readily spin coated. The phase, morphology, electrical and optical properties of the deposited films are investigated, by XRD (X-ray diffraction), scanning electron microscopy, a two-point contact measurement and UV–vis spectrophotometry respectively. This way, the effect of this solvent is investigated. The films are deposited on borosilicate glass substrates and were found to be continuous and smooth. XRD measurements show a highly preferential c-axis orientation. The effects of the thermal treatment profile and Al dopant concentration are studied with respect to the obtained electrical properties. Optimally, the electrical resistivity was lowered to 6.5 × 10 −3 Ω cm after annealing at 450 °C in a 95% He/5% H 2 atmosphere. - Highlights: ► 2-Butoxyethanol as alternative for 2-methoxyethanol for precursor synthesis. ► Al:ZnO thin films with a strong preferential c-axis orientation are obtained. ► A forming gas anneal greatly improves the electrical properties. ► The addition of 1 at.% Al is found to improve the electrical properties.

Characterization of Optic Properties ZnO:Al Thin Film on Glass Substrate for Solar Cell Window

International Nuclear Information System (INIS)

Wiryoadi; Yunanto; Bambang Siswanto; Sri Sulamdari; Sudjatmoko

2002-01-01

It has been characterized a ZnO:Al thin film growth using sputtering technique for solar cell window. The aims of this research is to get a ZnO:Al thin film that can be used as a TCO (Transparent Conducting Oxide) on amorphous silicon solar cell. To get an optimum properties, deposition process has been done for various parameters, such as composition/concentration of Al, substrate temperature, gas pressure and deposition time. Based on experiments result, it is found that the optimum result was achieved at temperature 450 o C, gas pressure 6 x 10 -2 torr and time 1.5 hours. From optical properties (transmittance) measurements using UV-vis, it was found that the optimum results was achieved at temperature 450 o C. At this conditions, wave length (500 - 800) nm, the transmittance was (50 - 82) %, at pressure 6 x 10 -2 torr the transmittance was (50 - 80) % and at deposition time 1.5 hours was (49 - 81) %. For ZnO thin film, was at wave length (500 - 800) nm, the transmittance was (78 - 80) %. From micro structure analysis using SEM, it was found that the thickness layer of ZnO was 1.5 μm and 1.3 μm for ZnO: Al. While from surface morphology it was found that for ZnO thin layer the grains was distributed homogeneously, while for ZnO: Al the grains was distributed unhomogeneously. (author)

Low-temperature heteroepitaxial growth of InAlAs layers on ZnSnAs{sub 2}/InP(001)

Energy Technology Data Exchange (ETDEWEB)

Oomae, Hiroto; Suzuki, Akiko; Toyota, Hideyuki; Uchitomi, Naotaka [Department of Electrical Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188, Niigata (Japan); Nakamura, Shin' ichi [Center for Instrumental Analysis, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara 252-0206, Kanagawa (Japan)

2015-06-15

We studied the epitaxial growth of InAlAs on ZnSnAs{sub 2} thin films to establish magnetic heterostructures involving ferromagnetic Mn-doped ZnSnAs{sub 2} (ZnSnAs{sub 2}:Mn) thin films. These heterostructures were successfully grown at temperatures around 300 C to maintain room-temperature ferromagnetism in ZnSnAs{sub 2}:Mn. Reflection high-energy electron diffraction, X-ray diffraction measurements and cross-sectional transmission electron microscopy revealed that the InAlAs layers were pseudomorphically lattice-matched with ZnSnAs{sub 2,} even at the low temperature of 300 C. We attempted to prepare magnetic quantum well structures from the InAlAs/ZnSnAs{sub 2}:Mn magnetic multilayer structure. We found that InAlAs layers heteroepitaxially grown on ZnSnAs{sub 2} and ferromagnetic ZnSnAs{sub 2}:Mn films are suitable for preparing InP-based magnetic semiconductor quantum structures. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Differential Scanning Calorimetry and Thermodynamic Predictions—A Comparative Study of Al-Zn-Mg-Cu Alloys

Directory of Open Access Journals (Sweden)

Gernot K.-H. Kolb

2016-08-01

Full Text Available Al-Zn-Mg-Cu alloys are widely used in aircraft applications because of their superior mechanical properties and strength/weight ratios. Commercial Al-Zn-Mg-Cu alloys have been intensively studied over the last few decades. However, well-considered thermodynamic calculations, via the CALPHAD approach, on a variation of alloying elements can guide the fine-tuning of known alloy systems and the development of optimized heat treatments. In this study, a comparison was made of the solidus temperatures of different Al-Zn-Mg-Cu alloys determined from thermodynamic predictions and differential scanning calorimetry (DSC measurements. A variation of the main alloying elements Zn, Mg, and Cu generated 38 experimentally produced alloys. An experimental determination of the solidus temperature via DSC was carried out according to a user-defined method, because the broad melting interval present in Al-Zn-Mg-Cu alloys does not allow the use of the classical onset method for pure substances. The software algorithms implemented in FactSage®, Pandat™, and MatCalc with corresponding commercially available databases were deployed for thermodynamic predictions. Based on these investigations, the predictive power of the commercially available CALPHAD databases and software packages was critically reviewed.

Near white light emitting ZnAl2O4:Dy3+ nanocrystals: Sol–gel synthesis and luminescence studies

International Nuclear Information System (INIS)

Kumar, Mithlesh; Gupta, Santosh K.; Kadam, R.M.

2016-01-01

Highlights: • ZnAl 2 O 4 :Dy 3+ spinel synthesized using sol–gel method. • Characterized by XRD, SEM and PL spectroscopy. • Investigations of emission, excitation and lifetime properties. • Evaluation of defect centers and trap parameters of the system. • Evaluation of CIE indices of near white light emitting phosphor. - Abstract: ZnAl 2 O 4 :Dy 3+ nanoparticles were synthesized using citrate sol–gel method and characterized systematically using X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy. Emission spectrum of pure ZnAl 2 O 4 shows intense violet blue emission under ultra violet irradiation. Based on electron paramagnetic resonance (EPR) results; it was attributed to presence of singly ionized oxygen vacancy centres in ZnAl 2 O 4 . On doping Dy 3+ in ZnAl 2 O 4 , complete host–dopant energy transfer does not take place. Local structural investigation and lifetime measurements reveal that dysprosium ion is distributed between both Zn 2+ and Al 3+ sites. Near white light from ZnAl 2 O 4 :Dy 3+ is attributed to combined host and dopant luminescence. The trap parameters such as activation energy (E) and frequency factor (s) for TSL glow peak 165 °C were determined using different heating rate method. Thermally stimulated emission showed the presence of oxygen related defect centre.

Exploration of Al-Doped ZnO in Photovoltaic Thin Films

Science.gov (United States)

Ciccarino, Christopher; Sahiner, M. Alper

The electrical properties of Al doped ZnO-based thin films represent a potential advancement in the push for increasing solar cell efficiency. Doping with Aluminum will theoretically decrease resistivity of the film and therefore achieve this potential as a viable option in the P-N junction phase of photovoltaic cells. The n-type semi-conductive characteristics of the ZnO layer will theoretically be optimized with the addition of Aluminum carriers. In this study, Aluminum doping concentrations ranging from 1-3% by mass were produced, analyzed, and compared. Films were developed onto ITO coated glass using the Pulsed Laser Deposition technique. Target thickness was 250 nm and ellipsometry measurements showed uniformity and accuracy in this regard. Active dopant concentrations were determined using Hall Effect measurements. Efficiency measurements showed possible applications of this doped compound, with upwards of 7% efficiency measured, using a Keithley 2602 SourceMeter set-up. XRD scans showed highly crystalline structures, with effective Al intertwining of the hexagonal wurtzile ZnO molecular structure. This alone indicates a promising future of collaboration between these two materials.

Precipitation behavior and grain refinement of burnishing Al-Zn-Mg alloy

Directory of Open Access Journals (Sweden)

Ce Pang

2018-02-01

Full Text Available Burnishing is a unique strengthening approach to improve the strength of surface layer and remains the ductility of the interior of metallic materials. In this work, burnishing treatment was employed to improve the surface microstructure of naturally aged Al-Zn-Mg alloys after solid solution. Transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction and nano-indentation were used to characterize the effects of the burnishing on the microstructures of surface layer and Guinier-Preston (GP zones. It was indicated that GP zones uniformly distributed and dispersed in the matrix before burnishing, and the amount of GP zones decreased dramatically after burnishing processing. Additionally, the grains in the surficial layer were refined into nano-crystals with an average grain size of 78 nm. Burnishing treatment not only led to formation of large number of dislocation substructures in the sub-surface and near-matrix surface, but also promoted the precipitation of metastable η' phase at grain boundaries. The synergistic effects of the grain refinement, dislocation multiplication and the precipitation of η' phase strengthen the burnished layer of Al-Zn-Mg alloy. Keywords: Al-Zn-Mg alloy, Burnishing, Nano-crystal, Precipitation, Grain refinement

Structural, vibrational and morphological properties of layered double hydroxides containing Ni2+, Zn2+, Al3+ and Zr4+ cations

International Nuclear Information System (INIS)

Bezerra, Débora M.; Rodrigues, João E.F.S.; Assaf, Elisabete M.

2017-01-01

Layered double hydroxides are anionic clays with formula [M II 1−x M III x (OH) 2 ] q+ [A n− ] q/n ·mH 2 O, finding possible uses as catalyst support, adsorbents and so on. In this paper, we address the phase formation of layered double hydroxides containing Ni 2+ , Zn 2+ , Al 3+ and Zr 4+ cations, namely, NiZn-Al, NiZn-AlZr and NiZn-Zr compositions obtained by the coprecipitation method. Such systems were characterized by X-ray diffraction, confirming the phase formation for NiZn-Al and NiZn-AlZr samples. Infrared and Raman spectroscopies elucidated the anion and water molecules occurrence in the interlayer. Nitrogen physisorption (BET method) determined the presence of pores and specific surface area. The isotherm shapes were Type IV, according to the IUPAC, and represent a mesoporous structure. A morphological study was performed by means of scanning and transmission electron microscopies, and particle size values of 120, 131 and 235 nm for NiZn-Al, NiZn-AlZr and NiZn-Zr, respectively, were determined. Thermogravimetric analysis of the decomposition of the systems revealed that their complete disintegration occurred at ~ 450 °C and resulted in mixed oxides.

MICROSTRUCTURAL ANALYSIS OF Al-Mg-Si-Zn ALLOY

Directory of Open Access Journals (Sweden)

SERGIO VALADEZ

2010-01-01

Full Text Available En un esfuerzo por desarrollar una nueva aleación con aplicación estructural, se ha desarrollado una aleación base Aluminio aleada con magnesio, silicio y zinc. La investigación pretende correlacionar la microestructura y con el tratamiento térmico. La aleación AlMgSiZn, fue elegida para ese propósito debido a la presencia de precipitados tanto en la matriz del aAl, como en los límites de grano, los cuales permiten una excelente relación entre la dureza y la resistencia mecánica. En lo que respecta a la microestructura, esta fue caracterizada bajo condición de colada y después de ser tratada térmicamente por envejecimiento. Este tratamiento fue realizado en dos etapas, la primera a 450ºC durante 3 horas que corresponde al tratamiento de homogeneización: y la segunda al proceso de envejecimiento artificial llevado a cabo a 160ºC durante 1hr. Los resultados indican la presencia de dendritas de aAl, además un eutéctico binario y partículas de Mg7Zn3 adentro de las regiones interdendríticas. El eutéctico y las partículas fueron modificados por el tratamiento de envejecido. Las observaciones realizadas con el microscopio electrónico de transmisión en especímenes con y sin tratamientos térmicos, demostraron una distribución uniforme de precipitados con diversas morfologías, tales como cúbico, esférico y plaqueta: para la matriz de aAl, los cuales no fueron detectados durante las observaciones en el microscopio electrónico de barrido.

Formation and Corrosion Resistance of Mg-Al Hydrotalcite Film on Mg-Gd-Zn Alloy

Science.gov (United States)

Ba, Z. X.; Dong, Q. S.; Kong, S. X.; Zhang, X. B.; Xue, Y. J.; Chen, Y. J.

2017-06-01

An environment-friendly technique for depositing a Mg-Al hydrotalcite (HT) (Mg6Al2(OH)16-CO3ṡ4H2O) conversion film was developed to protect the Mg-Gd-Zn alloy from corrosion. The morphology and chemical compositions of the film were analyzed by scanning electronic microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Raman spectroscopy (RS), respectively. The electrochemical test and hydrogen evolution test were employed to evaluate the biocorrosion behavior of Mg-Gd-Zn alloy coated with the Mg-Al HT film in the simulated body fluid (SBF). It was found that the formation of Mg-Al HT film was a transition from amorphous precursor to a crystalline HT structure. The HT film can effectively improve the corrosion resistance of magnesium alloy. It indicates that the process provides a promising approach to modify Mg-Gd-Zn alloy.

A study of Eu incorporated ZnO thin films: An application of Al/ZnO:Eu/p-Si heterojunction diode

Energy Technology Data Exchange (ETDEWEB)

Turgut, G. [Department of Basic Sciences, Faculty of Science, Erzurum Technical University, Erzurum, 25240 (Turkey); Duman, S., E-mail: sduman@atauni.edu.tr [Department of Physics, Faculty of Science, Ataturk University, Erzurum, 25240 (Turkey); Sonmez, E. [Department of Physics, Faculty of K.K. Education, Ataturk University, Erzurum, 25240 (Turkey); Ozcelik, F.S. [Department of Physics, Faculty of Science, Ataturk University, Erzurum, 25240 (Turkey)

2016-04-15

Highlights: • Eu incorporated ZnO thin films were grown by sol–gel spin coating. • The influence of Eu contribution on features of ZnO was investigated. • Al/ZnO:Eu/p-Si heterojunction diodes were also fabricated. • The diode parameters were calculated from I–V measurements. - Abstract: In present work, the pure and europium (Eu) incorporated zinc oxide (ZnO) thin films were deposited with sol-gel spin coating by using zinc acetate dehydrate and Eu (III) chloride salts. The coated films were examined by means of XRD, AFM and UV/VIS spectrophotometer. The ZnO hexagonal wurtzite nanoparticles with (002) preferential direction were observed for all films. The values of crystallite size, micro-strain and surface roughness continuously increased from 21 nm, 1.10 × 10{sup −3} and 2.43 nm to the values of 35.56 nm, 1.98 × 10{sup −3} and 28.99 nm with Eu doping, respectively. The optical band gap value of the pure ZnO initially increased from 3.296 eV to 3.328 eV with Eu doping up to 2 at.% doping level, then it started to decrease with more Eu content. The electrical features of Al/n-ZnO:Eu/p-Si heterojunction diodes were inquired by current-voltage (I–V) measurements at the room temperature.

Size- and morphology-dependent optical properties of ZnS:Al one-dimensional structures

Energy Technology Data Exchange (ETDEWEB)

Zeng, Xianghua, E-mail: xhzeng@yzu.edu.cn; Yan, Shunjun; Cui, Jieya; Liu, Hongfei; Dong, Jing; Xia, Weiwei; Zhou, Min; Chen, Haitao [Yangzhou University, School of Physics Science and Technology & Institute of Optoelectronic Technology (China)

2015-04-15

Typical morphology substrates can improve the efficiency of surface-enhanced Raman scattering; the need for SERS substrates of controlled morphology requires an extensive study. In this paper, one-dimensional ZnS:Al nanostructures with the width of approximately 300 nm and the length of tens um, and micro-scale structures with the width of several um and the length of tens um were synthesized via thermal evaporation on Au-coated silicon substrates and were used to study their size effects on Raman scattering and photoluminescent spectra. The photoluminescence spectra reveal the strongest green emission at a 5 at% Al source, which originates from the Al-dopant emission. The Raman spectra reveal that the size and morphology of the ZnS:Al nanowires greatly influences the Raman scattering, whereas the Al-dopant concentration has a lesser effect on the Raman scattering. The observed Raman scattering intensity of the saw-like ZnS:Al nanowires with the width of tens nm was eight times larger than that of the bulk sample. The enhanced Raman scattering can be regarded as multiple scattering and weak exciton—phonon coupling. The branched one-dimensional nanostructure can be used as an ideal substrate to enhance Raman scattering.

Laser Brazing Characteristics of Al to Brass with Zn-Based Filler

Science.gov (United States)

Tan, Caiwang; Liu, Fuyun; Sun, Yiming; Chen, Bo; Song, Xiaoguo; Li, Liqun; Zhao, Hongyun; Feng, Jicai

2018-05-01

Laser brazing of Al to brass in lap configuration with Zn-based filler was performed in this work. The process parameters including laser power, defocused distance were found to have a significant influence on appearance, microstructure and mechanical properties. The process parameters were optimized to be laser power of 2700 W and defocusing distance of + 40 mm from brass surface. In addition, preheating exerted great influence on wetting and spreading ability of Zn filler on brass surface. The microstructure observation showed the thickness of reaction layer (CuZn phase) at the interface of the brass side would grow with the increase in laser power and the decrease in the laser defocusing distance. Moreover, preheating could increase the spreading area of the filler metal and induced the growth of the reaction layer. The highest tensile-shear load of the joint could reach 2100 N, which was 80% of that of Al alloy base metal. All the joints fractured along the CuZn reaction layer and brass interface. The fracture morphology displayed the characteristics of the cleavage fracture when without preheating before welding, while it displayed the characteristics of the quasi-cleavage fracture with preheating before welding.

Electrochemical oxidation of 4-chloro phenol over a carbon paste electrode modified with Zn Al layered double hydroxides

International Nuclear Information System (INIS)

Hernandez F, D.; Palomar P, M.; Licona S, T. de J.; Romero R, M.; Valente, Jaime S.

2014-01-01

A study is presented on the electrochemical oxidation of 4-chloro phenol (4cp) in aqueous solution using a bare carbon paste electrode, Cpe, and another one that was modified with Zn Al layered double hydroxides (Cpe/Zn Al-LDH). The electro-oxidation was effected at ph values ranging from 3 up to 11. It was found through cyclic voltammetry that this process was irreversible, namely, there were no reduction peaks, and that depending on the nature of the electrode, the anodic current was limited either by adsorption (Cpe) or diffusion (Cpe/Zn Al-LDH). The energy required and the oxidation reaction rate depended on the ph and on the nature of the electrode, such that the greater rates were obtained when the Cpe/Zn Al-LDH electrode and acid ph were used. The Zn Al-LDH was characterized by means of X-ray diffraction. (Author)

Electrochemical oxidation of 4-chloro phenol over a carbon paste electrode modified with Zn Al layered double hydroxides

Energy Technology Data Exchange (ETDEWEB)

Hernandez F, D.; Palomar P, M.; Licona S, T. de J.; Romero R, M. [Universidad Autonoma Metropolitana, Unidad Azcapotzalco, Departamento de Materiales, Av. San Pablo 180, Col. Reynosa-Tamaulipas, 02200 Mexico D. F. (Mexico); Valente, Jaime S., E-mail: mepp@correo.azc.uam.mx [Instituto Mexicano del Petroleo, Eje Central No. 152, 07730 Mexico D. F. (Mexico)

2014-07-01

A study is presented on the electrochemical oxidation of 4-chloro phenol (4cp) in aqueous solution using a bare carbon paste electrode, Cpe, and another one that was modified with Zn Al layered double hydroxides (Cpe/Zn Al-LDH). The electro-oxidation was effected at ph values ranging from 3 up to 11. It was found through cyclic voltammetry that this process was irreversible, namely, there were no reduction peaks, and that depending on the nature of the electrode, the anodic current was limited either by adsorption (Cpe) or diffusion (Cpe/Zn Al-LDH). The energy required and the oxidation reaction rate depended on the ph and on the nature of the electrode, such that the greater rates were obtained when the Cpe/Zn Al-LDH electrode and acid ph were used. The Zn Al-LDH was characterized by means of X-ray diffraction. (Author)

Massive spalling of Cu-Zn and Cu-Al intermetallic compounds at the interface between solders and Cu substrate during liquid state reaction

Science.gov (United States)

Kotadia, H. R.; Panneerselvam, A.; Mokhtari, O.; Green, M. A.; Mannan, S. H.

2012-04-01

The interfacial intermetallic compound (IMC) formation between Cu substrate and Sn-3.8Ag-0.7Cu-X (wt.%) solder alloys has been studied, where X consists of 0-5% Zn or 0-2% Al. The study has focused on the effect of solder volume as well as the Zn or Al concentration. With low solder volume, when the Zn and Al concentrations in the solder are also low, the initial Cu-Zn and Al-Cu IMC layers, which form at the solder/substrate interface, are not stable and spall off, displaced by a Cu6Sn5 IMC layer. As the total Zn or Al content in the system increases by increasing solder volume, stable CuZn or Al2Cu IMCs form on the substrate and are not displaced. Increasing concentration of Zn has a similar effect of stabilizing the Cu-Zn IMC layer and also of forming a stable Cu5Zn8 layer, but increasing Al concentration alone does not prevent spalling of Al2Cu. These results are explained using a combination of thermodynamic- and kinetics-based arguments.

Grain boundary imaging, gallium diffusion and the fracture behavior of Al-Zn Alloy - An in situ study

Science.gov (United States)

Tsai, W. L.; Hwu, Y.; Chen, C. H.; Chang, L. W.; Je, J. H.; Lin, H. M.; Margaritondo, G.

2003-01-01

Phase contrast radiology using unmonochromatic synchrotron X-ray successfully imaged the grain boundaries of Al and AlZn alloy without contrast agent. Combining the high penetration of X-ray and the possibility of 3D reconstruction by tomorgraphy or stereography method, this approach can be very used for nondestructive characterization of polycrystalline materials. By examine the images with 3D perspective, we were able locate the observed void-like defects which lies exclusively on the grain boundary and identify their origin from last stage of the rolling process. We studied the Ga Liquid metal diffusion in the AlZn alloy, under different temperature and stress conditions. High resolution images, ˜2 μm, of Ga liquid metal diffusion in AlZn were obtained in real time and diffusion paths alone grain boundaries and surfaces were clearly identified. Embrittled AlZn responses to the tensile stress and fractures in a drastic different manner than the pure AlZn. These results, although very much expected from the known weakening effect of the liquid metal embrittlement demonstrated, however, that this particular radiology method is fully capable of dynamic study in the micrometer scale.

Comparative investigation on cation-cation (Al-Sn) and cation-anion (Al-F) co-doping in RF sputtered ZnO thin films: Mechanistic insight

Energy Technology Data Exchange (ETDEWEB)

Mallick, Arindam; Basak, Durga, E-mail: sspdb@iacs.res.in

2017-07-15

Highlights: • Comparative study on Al, Al-Sn and Al-F doped ZnO films has been carried out. • High transparent Al-F co-doped film shows three times enhanced carrier density. • Al-F co-doped film shows larger carrier relaxation time. • Al-Sn co-doped films shows carrier transport dominated by impurity scattering. • Al-F co-doped ZnO film can be applied as transparent electrode. - Abstract: Herein, we report a comparative mechanistic study on cation-cation (Al-Sn) and cation-anion (Al-F) co-doped nanocrystalline ZnO thin films grown on glass substrate by RF sputtering technique. Through detailed analyses of crystal structure, surface morphology, microstructure, UV-VIS-NIR transmission-reflection and electrical transport property, the inherent characteristics of the co-doped films were revealed and compared. All the nanocrystalline films retain the hexagonal wurtzite structure of ZnO and show transparency above 90% in the visible and NIR region. As opposed to expectation, Al-Sn (ATZO) co-doped film show no enhanced carrier concentration consistent with the probable formation of SnO{sub 2} clusters supported by the X-ray photoelectron spectroscopy study. Most interestingly, it has been found that Al-F (AFZO) co-doped film shows three times enhanced carrier concentration as compared to Al doped and Al-Sn co-doped films attaining a value of ∼9 × 10{sup 20} cm{sup −3} due to the respective cation and anion substitution. The carrier relaxation time increases in AFZO while it decreases significantly for ATZO film consistent with the concurrence of the impurity scattering in the latter.

Detecting the Extent of Eutectoid Transformation in U-10Mo

Energy Technology Data Exchange (ETDEWEB)

Devaraj, Arun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jana, Saumyadeep [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McInnis, Colleen A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lombardo, Nicholas J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sweet, Lucas E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Manandhar, Sandeep [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2016-08-31

During eutectoid transformation of U-10Mo alloy, uniform metastable γ UMo phase is expected to transform to a mixture of α-U and γ’-U₂Mo phase. The presence of transformation products in final U-10Mo fuel, especially the α phase is considered detrimental for fuel irradiation performance, so it is critical to accurately evaluate the extent of transformation in the final U-10Mo alloy. This phase transformation can cause a volume change that induces a density change in final alloy. To understand this density and volume change, we developed a theoretical model to calculate the volume expansion and resultant density change of U-10Mo alloy as a function of the extent of eutectoid transformation. Based on the theoretically calculated density change for 0 to 100% transformation, we conclude that an experimental density measurement system will be challenging to employ to reliably detect and quantify the extent of transformation. Subsequently, to assess the ability of various methods to detect the transformation in U-10Mo, we annealed U-10Mo alloy samples at 500°C for various times to achieve in low, medium, and high extent of transformation. After the heat treatment at 500°C, the samples were metallographically polished and subjected to optical microscopy and x-ray diffraction (XRD) methods. Based on our assessment, optical microscopy and image processing can be used to determine the transformed area fraction, which can then be correlated with the α phase volume fraction measured by XRD analysis. XRD analysis of U-10Mo aged at 500°C detected only α phase and no γ’ was detected. To further validate the XRD results, atom probe tomography (APT) was used to understand the composition of transformed regions in U-10Mo alloys aged at 500°C for 10 hours. Based on the APT results, the lamellar transformation product was found to comprise α phase with close to 0 at% Mo and γ phase with 28–32 at% Mo, and the Mo concentration was highest at the �

Engineering of nearly strain-free ZnO films on Si(1 1 1) by tuning AlN buffer thickness

International Nuclear Information System (INIS)

Venkatachalapathy, Vishnukanthan; Galeckas, Augustinas; Lee, In-Hwan; Kuznetsov, Andrej Yu.

2012-01-01

ZnO properties were investigated as a function of AlN buffer layer thickness (0–100 nm) in ZnO/AlN/Si(1 1 1) structures grown by metal organic vapor phase epitaxy. A significant improvement of ZnO film crystallinity by tuning AlN buffer thickness was confirmed by x-ray diffraction, topography and photoluminescence measurements. An optimal AlN buffer layer thickness of 50 nm is defined, which allows for growth of nearly strain-free ZnO films. The presence of free excitons at 10 K suggests high crystal quality for all ZnO samples grown on AlN/Si(1 1 1) templates. The intensities of neutral and ionized donor bound exciton lines are found to correlate with the in-plane and out-of-plane strain in the films, respectively.

Engineering of nearly strain-free ZnO films on Si(1 1 1) by tuning AlN buffer thickness

Energy Technology Data Exchange (ETDEWEB)

Venkatachalapathy, Vishnukanthan, E-mail: vishnukanthan.venkatachalapathy@smn.uio.no [Department of Physics/Centre for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway); Galeckas, Augustinas [Department of Physics/Centre for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway); Lee, In-Hwan [School of Advanced Materials Engineering, Research Centre for Advanced Materials Development (RCAMD), Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Kuznetsov, Andrej Yu. [Department of Physics/Centre for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway)

2012-05-15

ZnO properties were investigated as a function of AlN buffer layer thickness (0-100 nm) in ZnO/AlN/Si(1 1 1) structures grown by metal organic vapor phase epitaxy. A significant improvement of ZnO film crystallinity by tuning AlN buffer thickness was confirmed by x-ray diffraction, topography and photoluminescence measurements. An optimal AlN buffer layer thickness of 50 nm is defined, which allows for growth of nearly strain-free ZnO films. The presence of free excitons at 10 K suggests high crystal quality for all ZnO samples grown on AlN/Si(1 1 1) templates. The intensities of neutral and ionized donor bound exciton lines are found to correlate with the in-plane and out-of-plane strain in the films, respectively.

Measurement of ZnO/Al2O3 Heterojunction Band Offsets by in situ X-Ray Photoelectron Spectroscopy

International Nuclear Information System (INIS)

Lei Hong-Wen; Zhang Hong; Wang Xue-Min; Zhao Yan; Yan Da-Wei; Jiang Zhong-Qian; Yao Gang; Zeng Ti-Xian; Wu Wei-Dong

2013-01-01

ZnO films are grown on c-sapphire substrates by laser molecular beam epitaxy. The band offsets of the ZnO/Al 2 O 3 heterojunction are studied by in situ x-ray photoelectron spectroscopy. The valence band of Al 2 O 3 is found to be 3.59±0.05eV below that of ZnO. Together with the resulting conduction band offset of 2.04±0.05eV, this indicates that a type-I staggered band line exists at the ZnO/Al 2 O 3 heterojunction

The influence of the UV irradiation intensity on photocatalytic activity of ZnAl layered double hydroxides and derived mixed oxides

Directory of Open Access Journals (Sweden)

Hadnađev-Kostić Milica S.

2012-01-01

Full Text Available Layered double hydroxides (LDHs have been studied to a great extent as environmental-friendly complex materials that can be used as photocatalysts or photocatalyst supports. ZnAl layered double hydroxides and their derived mixed oxides were chosen for the investigation of photocatalytic performances in correlation with the UV intensities measured in the South Pannonia region. Low supersaturation coprecipitation method was used for the ZnAl LDH synthesis. For the characterization of LDH and thermal treated samples powder X-ray diffraction (XRD, scanning electron microscopy (SEM, electron dispersive spectroscopy (EDS, nitrogen adsorption-desorption were used. The decomposition of azodye, methylene blue was chosen as photocatalytic test reaction. The study showed that the ZnAl mixed oxide obtained by thermal decomposition of ZnAl LDH has stable activity in the broader UV light irradiation range characterizing the selected region. Photocatalytic activity could be mainly attributed to the ZnO phase, detected both in LDH and thermally treated samples. The study showed that the ZnAl mixed oxide obtained by the calcination of ZnAl LDH has a stable activity within the measured UV light irradiation range; whereas the parent ZnAl LDH catalyst did not perform satisfactory when low UV irradiation intensity is implied.

Electrical characterization of Ni/n-ZnO/p-Si/Al heterostructure fabricated by pulsed laser deposition technique

International Nuclear Information System (INIS)

Chand, Subhash; Kumar, Rajender

2014-01-01

Highlights: • The Ni/n-ZnO/p-Si/Al heterojunction diodes are fabricated by pulsed laser deposition. • The band gap of the deposit ZnO films was found to be 3.43 eV. • Forward I–V data of Ni/n-ZnO/p-Si/Al hetrojunction are interpreted in terms of thermionic emission–diffusion mechanism. • The C–V characteristics of the Ni/n-ZnO/p-Si/Al hetrojunction diode are measured in the temperature range 80–300 K. • The barrier height of Ni/n-ZnO/p-Si/Al hetrojunction diode is also calculated from C–V measurements. - Abstract: The ZnO thin films are grown on the p-Si for the heterojunction fabrication by pulsed laser deposition method. X-ray diffraction study showed that the texture of the film is hexagonal with a strong (0 0 2) plane as preferred direction. High purity vacuum evaporated nickel and aluminum metals were used to make contacts to the n-ZnO and p-Si, respectively. The current–voltage characteristics of Ni/n-ZnO/p-Si(1 0 0)/Al hetero structure measured over the temperature range 80–300 K have been studied on the basis of thermionic emission diffusion mechanism. The equivalent Schottky barrier height and diode ideality factor are determined by fitting of measured current–voltage data in to thermionic diffusion equation. It is observed that the barrier height decreases and the ideality factor increases with decrease of temperature and the activation energy plot exhibit non-linear behavior. These characteristics are attributed to the Gaussian distribution of barrier heights. The capacitance–voltage characteristics of Ni/n-ZnO/p-Si(1 0 0)/Al heterojunction diode are also studied over wide temperature range. From the measured capacitance–voltage data the built in voltage and impurity concentration in n-type ZnO is estimated

Fabrication of p-Si/n-ZnO:Al heterojunction diode and determination of electrical parameters

Science.gov (United States)

Ilican, Saliha; Gorgun, Kamuran; Aksoy, Seval; Caglar, Yasemin; Caglar, Mujdat

2018-03-01

We present a fundamental experimental study of a microwave assisted chemical bath deposition (MW-CBD) method for Al doped ZnO films. Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) spectroscopy were used to analyze the microstructures and crystalline structures of these films, respectively. The p-Si/n-ZnO:Al heterojunction diodes were fabricated. The current-voltage (I-V) characteristics of these diodes were measured at room temperature. The important electrical parameters such as series resistance, the ideality factor and the barrier height were determined by performing plots from the forward bias I-V characteristics using different methods. The obtained results indicate that Al doping improve the electrical properties of the p-Si/n-ZnO diode. The best rectification properties were observed in the p-Si/n-ZnO:5%Al heterojunction diode, so only capacitance-voltage (C-V) measurements of this diode were taken. Electrical parameter values such as series resistance, the built-in potential and the acceptor concentration calculated for this heterojunction diode.

ANTS-anchored Zn-Al-CO3-LDH particles as fluorescent probe for sensing of folic acid

International Nuclear Information System (INIS)

Liu, Pengfei; Liu, Dan; Liu, Yanhuan; Li, Lei

2016-01-01

A novel fluorescent nanosensor for detecting folic acid (FA) in aqueous media has been developed based on 8-aminonaphthalene-1,3,6-trisulfonate (ANTS) anchored to the surface of Zn-Al-CO 3 -layered double hydroxides (LDH) particles. The nanosensor showed high fluorescence intensity and good photostability due to a strong coordination interaction between surface Zn 2+ ions of Zn-Al-CO 3 -LDH and N atoms of ANTS, which were verified by result of X-ray photoelectron spectroscopy (XPS). ANTS-anchored on the surface of Zn-Al-CO 3 -LDH restricted the intra-molecular rotation leading to ANTS-anchored J-type aggregation emission enhancement. ANTS-anchored Zn-Al-CO 3 -LDH particles exhibited highly sensitive and selective response to FA over other common metal ions and saccharides present in biological fluids. The proposed mechanism was that oxygen atoms of -SO 3 groups in ANTS-anchored on the surface of Zn-Al-CO 3 -LDH were easily collided by FA molecules to form potential hydrogen bonds between ANTS-anchored and FA molecules, which could effectively quench the ANTS-anchored fluorescence. Under the simulated physiological conditions (pH of 7.4), the fluorescence quenching was fitted to Stern-Volmer equation with a linear response in the concentration range of 1 μM to 200 μM with a limit of detection of 0.1 μM. The results indicate that ANTS-anchored Zn-Al-CO 3 -LDH particles can afford a very sensitive system for the sensing FA in aqueous solution. - Highlights: • A novel fluorescent nanosensor has been developed. • The sensor exhibited highly sensitive and selective response to FA. • The fluorescence quenching was fitted to Stern–Volmer equation. • The linear response range was 1–200 μM with a limit of detection of 0.1 μM.

Lattice dynamics of ZnAl{sub 2}O{sub 4} and ZnGa{sub 2}O{sub 4} under high pressure

Energy Technology Data Exchange (ETDEWEB)

Lopez-Moreno, S.; Rodriguez-Hernandez, P.; Munoz, A. [Departamento de Fisica Fundamental II, MALTA Consolider Team, Instituto de Materiales y Nanotecnologia Universidad de La Laguna, La Laguna 38205, Tenerife (Spain); Romero, A.H. [CINVESTAV-Queretaro Libramiento Norponiente No 2000 Real de Juriquilla 76230 Queretaro, Qro (Mexico); Manjon, F.J. [Instituto de Diseno para la Fabricacion y Produccion Automatizada, MALTA Consolider Team, Universitat Politecnica de Valencia, 46022 Valencia (Spain); Errandonea, D. [Fundacion General de la Universidad de Valencia ICMUV, MALTA Consolider Team, Edificio de Investigacion, C/Dr. Moliner 50, Burjassot, 46100 Valencia (Spain); Rusu, E.; Ursaki, V.V. [Institute of Applied Physics, Academy of Sciences of Moldova, 2028 Chisinau (Moldova)

2011-01-15

In this work we present a first-principles density functional study of the vibrational properties of ZnAl{sub 2}O{sub 4} and ZnGa{sub 2}O{sub 4} as function of hydrostatic pressure. Based on our previous structural characterization of these two compounds under pressure, herewith, we report the pressure dependence on both systems of the vibrational modes for the cubic spinel structure, for the CaFe{sub 2}O{sub 4}-type structure (Pnma) in ZnAl{sub 2}O{sub 4} and for marokite (Pbcm) ZnGa{sub 2}O{sub 4}. Additionally we report a second order phase transition in ZnGa{sub 2}O{sub 4} from the marokite towards the CaTi{sub 2}O{sub 4}-type structure (Cmcm), for which we also calculate the pressure dependence of the vibrational modes at the {gamma} point. Our calculations are complemented with Raman scattering measurements up to 12 GPa that show a good overall agreement between our calculated and measured mode frequencies. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Design and fabrication of enhanced corrosion resistance Zn-Al layered double hydroxides films based anion-exchange mechanism on magnesium alloys

Science.gov (United States)

Zhou, Meng; Yan, Luchun; Ling, Hao; Diao, Yupeng; Pang, Xiaolu; Wang, Yanlin; Gao, Kewei

2017-05-01

Layered double hydroxides (LDHs) with brucite-like layer structure and the facile exchangeability of intercalated anions had attracted tremendous interest in many fields because of their great importance for both fundamental studies and practical applications. Herein zinc-aluminum layered double hydroxides (Zn-Al LDHs) films intercalated with nitrate anions on the magnesium alloy substrate were designed and fabricated via a facile hydrothermal crystallization method. In order to obtain better corrosion resistance, chloride and vanadate anions were intercalated into the LDHs interlayers via the anion-exchange reaction. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electronic microscopy (SEM) were used to examine structure, composition and morphology of the Zn-Al-NO3 LDHs, Zn-Al-Cl LDHs and Zn-Al-VOx LDHs films. The corrosion resistance of the Zn-Al LDHs with different anion films was estimated by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurement. EIS and polarization curves measurements revealed that the magnesium alloy could be effectively protected by the Zn-Al-Cl LDHs and Zn-Al-VOx LDHs films due to the blocking effect of chloride anions and the control-release ability of vanadate anions.

Interfacial microstructures and solder joint strengths of the Sn-8Zn-3Bi and Sn-9Zn-lAl Pb-free solder pastes on OSP finished printed circuit boards

Energy Technology Data Exchange (ETDEWEB)

Lin, C.-T. [Department of Materials Science and Engineering, National United University, 1 Lein-Da, Kung-Ching Li, Miaoli 36003, Taiwan (China); Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, 195 Section 4, Chung-Hsing Road, Chutung, Hsinchu 31040, Taiwan (China); Hsi, C.-S. [Department of Materials Science and Engineering, National United University, 1 Lein-Da, Kung-Ching Li, Miaoli 36003, Taiwan (China); Wang, M.-C. [Faculty of Fragrance and Cosmetics, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China)], E-mail: mcwang@kmu.edu.tw; Chang, T.-C.; Liang, M.-K. [Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, 195 Section 4, Chung-Hsing Road, Chutung, Hsinchu 31040, Taiwan (China)

2008-07-14

Two kinds of lead-free solders, Sn-8Zn-3Bi and Sn-9Zn-lAl, were used to mount passive components onto printed circuit boards via a re-flow soldering process. The samples were stored at 150 deg. C for 200, 400, 600, 800, and 1100 h. The microstructures of the samples after aged at 150 deg. C for various times were characterized using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and the analyzed of solder joint shear strengths. The joint strength between Sn-8Zn-3Bi and Cu pad was about 4.0 {+-} 0.3 kg, while the strength between Sn-9Zn-lAl and Cu pad had values of 2.6 {+-} 0.1 kg. Both kinds of solder joints exhibited reduced strengths with increasing aging times. After aging at 150 deg. C for 1100 h, the joints strengths of Sn-8Zn-3Bi and Sn-9Zn-lAl were 1.8 {+-} 0.3 and 1.7 {+-} 0.3 kg, respectively. Both the Sn-8Zn-3Bi and Sn-9Zn-lAl joints showed brittle fracture behaviors. A flat layer of Cu{sub 5}Zn{sub 8} intermetallic compound (IMC) was formed between Sn-8Zn-3Bi solder and Cu pad after reflow. When the aging time was increased to 400 h, Zn-depletion and formation of Cu{sub 6}Sn{sub 5} IMC were observed in the solders due to the interaction between the tin and zinc compounds. The interaction between Sn-9Zn-lAl solder and Cu pad had similar behavior, however, Cu{sub 6}Sn{sub 5} IMC formed in Sn-9Zn-lAl solder when after aging at 150 deg. C for 600 h. As the aging time increased, both types of solders generated clear IMC spalling layers with large and continuous voids. Those voids substantially decreased the joint strength.

Solution derived ZnO:Al films with low resistivity

Energy Technology Data Exchange (ETDEWEB)

Schellens, K. [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, Agoralaan, Building D, 3590 Diepenbeek (Belgium); Capon, B. [Ghent University, Department of Solid State Sciences, Krijgslaan 281/S1, 9000 Ghent (Belgium); IMEC and SIM program SoPPoM, Kapeldreef 75, 3001 Leuven (Belgium); De Dobbelaere, C. [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, Agoralaan, Building D, 3590 Diepenbeek (Belgium); Detavernier, C. [Ghent University, Department of Solid State Sciences, Krijgslaan 281/S1, 9000 Ghent (Belgium); IMEC and SIM program SoPPoM, Kapeldreef 75, 3001 Leuven (Belgium); Hardy, A. [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, Agoralaan, Building D, 3590 Diepenbeek (Belgium); IMEC vzw, Division IMOMEC, Institute for Materials Research, Wetenschapspark 1, 3590 Diepenbeek (Belgium); IMEC and SIM program SoPPoM, Kapeldreef 75, 3001 Leuven (Belgium); Van Bael, M.K., E-mail: marlies.vanbael@uhasselt.be [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, Agoralaan, Building D, 3590 Diepenbeek (Belgium); IMEC vzw, Division IMOMEC, Institute for Materials Research, Wetenschapspark 1, 3590 Diepenbeek (Belgium); IMEC and SIM program SoPPoM, Kapeldreef 75, 3001 Leuven (Belgium)

2012-12-01

ZnO:Al thin films were prepared via chemical solution deposition, using 2-butoxyethanol as an alternative for 2-methoxyethanol, which is more commonly used, but acutely toxic. The precursor solutions can be readily spin coated. The phase, morphology, electrical and optical properties of the deposited films are investigated, by XRD (X-ray diffraction), scanning electron microscopy, a two-point contact measurement and UV-vis spectrophotometry respectively. This way, the effect of this solvent is investigated. The films are deposited on borosilicate glass substrates and were found to be continuous and smooth. XRD measurements show a highly preferential c-axis orientation. The effects of the thermal treatment profile and Al dopant concentration are studied with respect to the obtained electrical properties. Optimally, the electrical resistivity was lowered to 6.5 Multiplication-Sign 10{sup -3} {Omega} cm after annealing at 450 Degree-Sign C in a 95% He/5% H{sub 2} atmosphere. - Highlights: Black-Right-Pointing-Pointer 2-Butoxyethanol as alternative for 2-methoxyethanol for precursor synthesis. Black-Right-Pointing-Pointer Al:ZnO thin films with a strong preferential c-axis orientation are obtained. Black-Right-Pointing-Pointer A forming gas anneal greatly improves the electrical properties. Black-Right-Pointing-Pointer The addition of 1 at.% Al is found to improve the electrical properties.

ZnO:Al Thin Film Gas Sensor for Detection of Ethanol Vapor

Directory of Open Access Journals (Sweden)

Min Hsiung Hon

2006-10-01

Full Text Available The ZnO:Al thin films were prepared by RF magnetron sputtering on Si substrateusing Pt as interdigitated electrodes. The structure was characterized by XRD and SEManalyses, and the ethanol vapor gas sensing as well as electrical properties have beeninvestigated and discussed. The gas sensing results show that the sensitivity for detecting400 ppm ethanol vapor was ~20 at an operating temperature of 250°C. The high sensitivity,fast recovery, and reliability suggest that ZnO:Al thin film prepared by RF magnetronsputtering can be used for ethanol vapor gas sensing.

Mechano-luminescence studies of nano ZnMgAl10O17:Eu phosphor under UV irradiation

Science.gov (United States)

Verma, Akshkumar; Verma, Ashish; Panda, Maheswar

2018-05-01

ZnMgAl10O17:Eu nano phosphors were prepared successfully, using the combustion route by employing urea as a fuel. The structural, and Morphological, properties were measured using x-ray diffraction (XRD) Scanning electron microscopy (SEM) transition electron microscopy. The BET surface area of sample were found to be of ˜13.92 m2/g. The ML (Mechano-luminescence) were measured to the home made instrument. The phosphor showed more strong and high ML intensity to the without UV irradiated material. Therefore ZnMgAl10O17:Eu2+ phosphor may use as a damage sensor and dosimetry material. The ML emission spectra of the Zn0.99MgAl10O17:Eu0.01 phosphor showed the characteristic Eu2+ emission peaks ˜453nm (blue) originating from the transitions 4f65d1→4f7, Therefore ZnMgAl10O17:Eu2+ phosphor may use as a blue phosphor material.

Industrial high-rate (~14 nm/s) deposition of low resistive and transparent ZnOx:Al films on glass

NARCIS (Netherlands)

Illiberi, A.; Kniknie, B.; Deelen, J. van; Steijvers, H.L.A.H.; Habets, D.; Simons, P.J.P.M.; Janssen, A.C.; Beckers, E.H.A.

2011-01-01

Aluminum doped ZnOx (ZnOx:Al) films have been deposited on glass in an in-line industrial-type reactor by a metalorganic chemical vapor deposition process at atmospheric pressure. Tertiary-butanol has been used as oxidant for diethylzinc and trimethylaluminium as dopant gas. ZnOx:Al films can be

Thermal and Microstructure Characterization of Zn-Al-Si Alloys and Chemical Reaction with Cu Substrate During Spreading

Science.gov (United States)

Berent, Katarzyna; Pstruś, Janusz; Gancarz, Tomasz

2016-08-01

The problems associated with the corrosion of aluminum connections, the low mechanical properties of Al/Cu connections, and the introduction of EU directives have forced the potential of new materials to be investigated. Alloys based on eutectic Zn-Al are proposed, because they have a higher melting temperature (381 °C), good corrosion resistance, and high mechanical strength. The Zn-Al-Si cast alloys were characterized using differential scanning calorimetry (DSC) measurements, which were performed to determine the melting temperatures of the alloys. Thermal linear expansion and electrical resistivity measurements were performed at temperature ranges of -50 to 250 °C and 25 to 300 °C, respectively. The addition of Si to eutectic Zn-Al alloys not only limits the growth of phases at the interface of liquid solder and Cu substrate but also raises the mechanical properties of the solder. Spreading test on Cu substrate using eutectic Zn-Al alloys with 0.5, 1.0, 3.0, and 5.0 wt.% of Si was studied using the sessile drop method in the presence of QJ201 flux. Spreading tests were performed with contact times of 1, 8, 15, 30, and 60 min, and at temperatures of 475, 500, 525, and 550 °C. After cleaning the flux residue from solidified samples, the spreadability of Zn-Al-Si on Cu was determined. Selected, solidified solder/substrate couples were cross-sectioned, and the interfacial microstructures were studied using scanning electron microscopy and energy dispersive x-ray spectroscopy. The growth of the intermetallic phase layer was studied at the solder/substrate interface, and the activation energy of growth of Cu5Zn8, CuZn4, and CuZn phases were determined.

Insitu grown superhydrophobic Zn-Al layered double hydroxides films on magnesium alloy to improve corrosion properties

Science.gov (United States)

Zhou, Meng; Pang, Xiaolu; Wei, Liang; Gao, Kewei

2015-05-01

A hierarchical superhydrophobic zinc-aluminum layered double hydroxides (Zn-Al LDHs) film has been fabricated on a magnesium alloy substrate via a facile hydrothermal crystallization method following chemical modification. The characteristics of the films were investigated by X-ray diffraction (XRD), scanning electronic microscope (SEM), and energy dispersive spectroscopy (EDS). XRD patterns and SEM images showed that the micro/nanoscale hierarchical LDHs film surfaces composed of ZnO nanorods and Zn-Al LDHs nanowalls structures. The static contact angle (CA) for the prepared surfaces was observed at around 165.6°. The corrosion resistance of the superhydrophobic films was estimated by electrochemical impedance spectroscopy (EIS) and potentiondynamic polarization measurement. EIS and polarization measurements revealed that the superhydrophobic Zn-Al LDHs coated magnesium alloy had better corrosion resistance in neutral 3.5 wt.% NaCl solution.

Water-n-BuOH solvothermal synthesis of ZnAl-LDHs with different morphologies and its calcined product in efficient dyes removal.

Science.gov (United States)

Huang, Gailing; Sun, Yingying; Zhao, Chencong; Zhao, Yifei; Song, Zhaoyuan; Chen, Junli; Ma, Shulan; Du, Junping; Yin, Zhigang

2017-05-15

In this study, water-n-BuOH mixed solvents were used to synthesize the ZnAl-layered double hydroxides (ZnAl-LDHs) via hydrothermal method. The XRD, FT-IR, SEM, ICP and CHN analyses revealed that the type of intercalated anions, the layer Zn/Al ratios, and morphologies of the LDHs depended on the ratio of V(water)/V(n-BuOH) in the mixed solvents. When the ratio of V(water)/V(n-BuOH) is 3 or 0.3, the as-prepared LDHs had 3D "silk flowers" (ZnAl-LDH-3) or "Sedimentary rock" morphology (ZnAl-LDH-0.3). Adsorption properties of dyes on calcined LDHs were studied. Compared with ZnAl-LDO-0.3 and ZnAl-LDO-w (calcined from the LDHs obtained in pure water), ZnAl-LDO-3 showed much better adsorption efficiency for anionic dyes thanks to its much larger BET-specific surface area. The sorption kinetics for dyes was appropriately described by the pseudo-second-order model and sorption isotherms can be fitted more satisfactorily by the Langmuir model. With the increasing concentrations of dyes from 10mg/L to 400mg/L, the maximum absorption capacities of ZnAl-LDO-3 were 1540mg/g (2.21mmol/g) for congo red, 1153mg/g (3.52mmol/g) for methyl orange and 390mg/g (0.63mmol/g) for active red (X-3B), respectively. The adsorption dyes onto the external surface is still the main mechanism for LDO adsorbents. The ZnAl-LDO-3 was a potential adsorbent for dyeing wastewater treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

Synthesis, characterization and photocatalytic activity of mixed oxides derived from ZnAlTi ternary layered double hydroxides

Science.gov (United States)

Sahu, R. K.; Mohanta, B. S.; Das, N. N.

2013-09-01

A new series of Ti4+ containing ZnAl-LDHs with varying Zn:Al:Ti (~3:1:0-3:0.5:0.5) ratio were prepared by coprecipitation of homogeneous solution metal salts and characterized by various physicochemical methods. Powder XRD revealed the formation of well crystallized LDH even at the highest Ti4+ content. On thermal treatment at 450 °C, the well crystallized LDH precursors yielded mixed oxides with BET surface area in the range 92-118 m2/g. UV-vis diffuse reflection spectroscopy (DRS) showed a marginal decrease of band gap energy for calcined ZnAlTi-LDHs in comparison to either ZnO or TiO2-P25. The TEM analyses of a representative sample (as-synthesized and calcined) indicated more or less uniform distribution of titanium species. The derived mixed oxides from titanium containing LDH precursors demonstrated better activity toward photodegradation of methylene blue and rhodamine B than those of a physical mixture of ZnO and TiO2. Moreover, the present work not only provided a first hand understanding about semiconductor properties of ZnAlTi-LDHs but also demonstrated their potential as photocatalysts for degradation of organic pollutants.

Effects of pre-sputtered Al interlayer on the atomic layer deposition of Al{sub 2}O{sub 3} films on Mg–10Li–0.5Zn alloy

Energy Technology Data Exchange (ETDEWEB)

Wang, P.C.; Cheng, T.C. [Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan (China); Lin, H.C., E-mail: hclinntu@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan (China); Chen, M.J., E-mail: mjchen@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan (China); Lin, K.M. [Department of Materials Science and Engineering, Feng Chia University, Taichung, Taiwan (China); Yeh, M.T. [Amli Materials Technology Co. Ltd., New Taipei, Taiwan (China)

2013-04-01

In this study, a dual-layer of Al/Al{sub 2}O{sub 3} films was deposited on the Mg–10Li–0.5Zn substrate using both techniques of magnetron sputtering and atomic layer deposition (ALD). The pre-sputtered Al interlayer has a crystalline structure and the ALD-Al{sub 2}O{sub 3} film is amorphous. The Al interlayer could effectively obstruct the diffusion out of Li atoms from the Mg–10Li–0.5Zn substrate during the deposition of ALD-Al{sub 2}O{sub 3} film. The Mg–10Li–0.5Zn specimen with a dual-layer of Al/Al{sub 2}O{sub 3} films exhibits a much better corrosion resistance than those specimens with a single layer of sputtered Al or ALD-Al{sub 2}O{sub 3}.

Adsorption of heavy metals from aqueous solutions by Mg-Al-Zn mingled oxides adsorbent.

Science.gov (United States)

El-Sayed, Mona; Eshaq, Gh; ElMetwally, A E

2016-10-01

In our study, Mg-Al-Zn mingled oxides were prepared by the co-precipitation method. The structure, composition, morphology and thermal stability of the synthesized Mg-Al-Zn mingled oxides were analyzed by powder X-ray diffraction, Fourier transform infrared spectrometry, N 2 physisorption, scanning electron microscopy, differential scanning calorimetry and thermogravimetry. Batch experiments were performed to study the adsorption behavior of cobalt(II) and nickel(II) as a function of pH, contact time, initial metal ion concentration, and adsorbent dose. The maximum adsorption capacity of Mg-Al-Zn mingled oxides for cobalt and nickel metal ions was 116.7 mg g -1 , and 70.4 mg g -1 , respectively. The experimental data were analyzed using pseudo-first- and pseudo-second-order kinetic models in linear and nonlinear regression analysis. The kinetic studies showed that the adsorption process could be described by the pseudo-second-order kinetic model. Experimental equilibrium data were well represented by Langmuir and Freundlich isotherm models. Also, the maximum monolayer capacity, q max , obtained was 113.8 mg g -1 , and 79.4 mg g -1 for Co(II), and Ni(II), respectively. Our results showed that Mg-Al-Zn mingled oxides can be used as an efficient adsorbent material for removal of heavy metals from industrial wastewater samples.

Transformaciones de fase en aleaciones Zn-22%Al-2%Cu y Zn-22%Al-2%Cu-X (X = 1, 2 y 3%Ag envejecidas isotérmicamente

Directory of Open Access Journals (Sweden)

Flores-Ramos, Alfredo

2014-12-01

Full Text Available The study of phase transformations that take place in Zn-22%Al-2%Cu and Zn-22%Al-2%Cu-X (X = 1, 2 and 3%Ag alloys was carried out using X-Ray Diffraction (XRD and Scanning Electron Microscopy (SEM. Alloys were homogenized at 350 °C during 10 days and quenched at ~2 °C. Subsequently, samples were aged at 200 °C for different times. The initial microstructure consists in a matrix of fine equiaxial grains of α and η phases for all the alloys. Besides isolated particles of ε and Φ were observed without and with Ag addition, respectively. During the aging, the four phase reaction, α + ε→η + τ’, takes place to obtain the equilibrium η, α and τ’ phases. However, the Ag addition promotes the formation of the Φ phase, which retards or inhibits the four phase reaction. The stability of the Φ phase is obtained with 3%Ag, which could improve the dimensional stability of the alloy for future industrial applications.En el presente estudio sobre las transformaciones de fase en las aleaciones Zn-22%Al-2%Cu y Zn-22%Al-2%Cu-X (X = 1, 2 y 3%Ag se utilizó Difracción de Rayos X (DRX y Microscopía Electrónica de Barrido (MEB. Las aleaciones fueron homogeneizadas a 350 °C durante 10 días, templadas a ~2 °C y posteriormente envejecidas a 200 °C durante diferentes tiempos. Todas las aleaciones ensayadas presentaron una microestructura inicial formada por una matriz de granos finos y equiaxiales de las fases α y η. Además, para las aleaciones sin Ag se observa la presencia de partículas de la fase ε (CuZn4 y de Φ ((Ag, Cu Zn4 en las que se adicionó Ag. Durante el envejecido, ocurre la reacción de cuatro fases, α + ε→η + τ’, para obtener las fases de equilibrio η, α y τ’. Sin embargo, la adición de Ag promueve la formación de la fase Φ, la cual retarda e incluso inhibe la reacción de cuatro fases. La estabilidad de la fase Φ se obtiene con 3%Ag, lo que podría mejorar la estabilidad dimensional de la aleación para

Microstructure evolution of Al/Mg butt joints welded by gas tungsten arc with Zn filler metal

International Nuclear Information System (INIS)

Liu Fei; Zhang Zhaodong; Liu Liming

2012-01-01

Based on the idea of alloying welding seam, Gas tungsten arc welding method with pure Zn filler metal was chosen to join Mg alloy and Al alloy. The microstructures, phases, element distribution and fracture morphology of welding seams were examined. The results indicate that there was a transitional zone in the width of 80–100 μm between the Mg alloy substrate and fusion zone. The fusion zone was mainly composed of MgZn 2 , Zn-based solid solution and Al-based solid solution. The welding seam presented distinct morphology in different location owning to the quite high cooling rate of the molten pool. The addition of Zn metal could prevent the formation of Mg–Al intermetallics and form the alloyed welding seam during welding. Therefore, the tensile strengths of joints have been significantly improved compared with those of gas tungsten arc welded joints without Zn metal added. Highlights: ► Mg alloy AZ31B and Al alloy 6061 are welded successfully. ► Zinc wire is employed as a filler metal to form the alloyed welding seam. ► An alloyed welding seam is benefit for improving of the joint tensile strength.

Laser Weldability of High-Strength Al-Zn Alloys and Its Improvement by the Use of an Appropriate Filler Material

Science.gov (United States)

Enz, Josephin; Riekehr, Stefan; Ventzke, Volker; Huber, Norbert; Kashaev, Nikolai

2016-06-01

Heat-treatable Al-Zn alloys are promising candidates for use as structural lightweight materials in automotive and aircraft applications. This is mainly due to their high strength-to-density ratio in comparison to conventionally employed Al alloys. Laser beam welding is an efficient method for producing joints with high weld quality and has been established in the industry for many years. However, it is well known that aluminum alloys with a high Zn content or, more precisely, with a high (Zn + Mg + Cu) content are difficult to fusion weld due to the formation of porosity and hot cracks. The present study concerns the laser weldability of these hard-to-weld Al-Zn alloys. In order to improve weldability, it was first necessary to understand the reasons for weldability problems and to identify crucial influencing factors. Based on this knowledge, it was finally possible to develop an appropriate approach. For this purpose, vanadium was selected as additional filler material. Vanadium exhibits favorable thermophysical properties and, thereby, can improve the weldability of Al-Zn alloys. The effectiveness of the approach was verified by its application to several Al-Zn alloys with differing amounts of (Zn + Mg + Cu).

Prediction of hardness of the Zn-Al-Cu alloys of agreement by composition in weight; Prediccion de la dureza de la aleacion Zn-Al-Cu de acuerdo a su composicion en peso

Energy Technology Data Exchange (ETDEWEB)

Villegas-Cardenas, Jose David; Camarillo-Villegas, Alejandra; Juanico-Loran, Antonio [Universidad Politecnica del Valle de Mexico, Tultitlan, Estado de Mexico (Mexico)]. E-mails: jdvc76@yahoo.com.mx; v_c_a_77@hotmail.com; ajuanico@yahoo.com.mx; Espinosa-Rojas, Raul [Universidad Autonoma Metropolitana, Unidad Azcapotzalco (Mexico)]. E-mail: rer21@hotmail.com; Camacho-Olguin, Carlos [Universidad Politecnica del Valle de Mexico, Tultitlan, Estado de Mexico (Mexico)]. E-mail: ccamacho@upvm.edu.mx

2013-07-15

Ten alloys Zn-Al-Cu were developed in two parts, in agreement to two zones presented in the isopleth diagrams (Villas et al., 1995). The percentage of Cu and Al was systematically varied. Subsequently, hardness measurements were performed. These measurements allowed establishing two equations that predict the hardness with an error lower than 5%. With these equations, it is possible to obtain alloys that replace Al base alloys by a Zn base alloy, having the same hardness. This implicates also the elimination of the volumetric change in the presence of e phase. [Spanish] Se desarrollaron diez aleaciones Zn-Al-Cu divididas en dos partes, de acuerdo a dos zonas presentadas en los diagramas isopleticos de Hans (Villas et al., 1995). Se incremento el porcentaje de Cu y Al paulatinamente. Posteriormente se desarrollaron pruebas de macrodureza y de ese analisis se obtuvieron dos ecuaciones que permiten pronosticar y disenar aleaciones de una dureza determinada de acuerdo a su porcentaje en peso de cada elemento, con un error menor que 5%. Como se demuestra en este trabajo, con estas ecuaciones es posible desarrollar aleaciones sustitutas base aluminio por una aleacion base zinc o viceversa, teniendo la misma dureza para cada tipo de aleacion y eliminando el problema del cambio volumetrico debido a la presencia de la fase e.

Phase-coherent electron transport in (Zn, Al)Ox thin films grown by atomic layer deposition

Science.gov (United States)

Saha, D.; Misra, P.; Ajimsha, R. S.; Joshi, M. P.; Kukreja, L. M.

2014-11-01

A clear signature of disorder induced quantum-interference phenomena leading to phase-coherent electron transport was observed in (Zn, Al)Ox thin films grown by atomic layer deposition. The degree of static-disorder was tuned by varying the Al concentration through periodic incorporation of Al2O3 sub-monolayer in ZnO. All the films showed small negative magnetoresistance due to magnetic field suppressed weak-localization effect. The temperature dependence of phase-coherence length ( l φ ∝ T - 3 / 4 ), as extracted from the magnetoresistance measurements, indicated electron-electron scattering as the dominant dephasing mechanism. The persistence of quantum-interference at relatively higher temperatures up to 200 K is promising for the realization of ZnO based phase-coherent electron transport devices.

OPTICAL PROPERTIES OF Al:ZnO THIN FILM DEPOSITED BY DIFFERENT SOL-GEL TECHNIQUES: ULTRASONIC SPRAY PYROLYSIS AND DIP-COATING

Directory of Open Access Journals (Sweden)

Ebru Gungor

2016-08-01

Full Text Available Undoped and Al-doped ZnO polycrystalline thin films have been fabricated on glass substrates by using a computer-controlled dip coating (DC and ultrasonic spray pyrolysis (USP systems. The film deposition parameters of DC process were optimized for the samples. In this technique, the substrate was exposed to temperature gradient using a tube furnace. In the study, the other solvent-based technique was conventional USP. The zinc salt and Al salt concentrations in the solution were kept constant as 0.1 M and 2% of Zn salt’s molarity, respectively. The optical properties were compared for the films deposited two different techniques. The optical transmission of Al:ZnO/Glass/Al:ZnO sample dip coated and  the optical transmission of Al:ZnO/Glass sample ultrasonically sprayed were determined higher than 80% in the visible and near infrared region. Experimental optical transmittance spectra of the films in the forms of FilmA/Glass/FilmA and FilmA/glass were used to determine the optical constants. It was observed that the optical band gaps of Al doped ZnO films onto glass substrate were increases with increase of Al content and the absorption edge shifted to the shorter wavelength (blue shift compared with the undoped ZnO thin film.

Effect of Cooling Rate on the Microstructure of Al-Zn Alloys with Addition of Silicon as Nanocomposite

Directory of Open Access Journals (Sweden)

S. García-Villarreal

2013-01-01

Full Text Available Al-43.5Zn-1.5Si (wt% alloys are widely used as coatings on steel substrates. This kind of coatings is manufactured by hot-dip process, in which Si is added as solid particles or master alloy. The role of Si during formation of the coating is to control the metallurgical reactions between solid steel and liquid Al-Zn-Si alloy initially forming an AlZnFeSi intermetallic layer and next the excess of Si forms intermetallic compounds, which grows over this alloy layer, segregates into the Zn rich interdendritic regions, and solidifies as eutectic reaction product as massive particles with needle like morphology. Therefore, during the experimental procedure is very difficult to control the final morphology and distribution of the silicon phase. The acicular morphology of this phase greatly affects the mechanical properties of the alloy because it acts as stress concentrators. When the coated steel sheet is subjected to bending, the coating presents huge cracks due to the presence of silicon phase. Therefore, the aim of the paper was to propose a new methodology to control the silicon phase through its addition to Al-Zn alloy as nanocomposite and additionally determine the effect of cooling rate (between 10 and 50°Cs−1 on the solidification microstructure and mechanical properties of Al-Zn alloy.

Influence of divalent metal on the decomposition products of hydrotalcite-like ternary systems M{sup II}-Al-Cr (M{sup II} = Zn, Cd)

Energy Technology Data Exchange (ETDEWEB)

Perez, M.R.; Crespo, I.; Ulibarri, M.A.; Barriga, C. [Departamento de Quimica Inorganica e Ingenieria Quimica, Campus de Rabanales, Universidad de Cordoba, Cordoba (Spain); Rives, V. [GIR-QUESCAT, Departamento de Quimica Inorganica, Universidad de Salamanca, Salamanca (Spain); Fernandez, J.M., E-mail: um1feroj@uco.es [Departamento de Quimica Inorganica e Ingenieria Quimica, Campus de Rabanales, Universidad de Cordoba, Cordoba (Spain)

2012-02-15

Highlights: Black-Right-Pointing-Pointer LDHs M{sup II}-Al-Cr (M = Zn, Cd) with Cr in the layer or interlayer have been prepared. Black-Right-Pointing-Pointer LDHs Zn-Al or Zn-Cr decompose by heating forming ZnO and ZnAl{sub 2}O{sub 4} or ZnO and ZnCr{sub 2}O{sub 4}. Black-Right-Pointing-Pointer LDHs Zn-Al-Cr give rise to the formation of ZnO and the mixed spinel ZnAl{sub 2-x}Cr{sub x}O{sub 4}. Black-Right-Pointing-Pointer LDH Cd-Al-Cr shows the formation of CdO, CdCr{sub 2-x}Al{sub x}O{sub 4}, and (Al, Cr){sub 2}O{sub 3} mixed oxide. Black-Right-Pointing-Pointer Calcination of the CdAl-CrO{sub 4} give rise to (Al, Cr){sub 2}O{sub 3} as the majority phase. - Abstract: Layered double hydroxides (LDHs) containing M{sup II}, Al{sup III}, and Cr{sup III} in the brucite-like layers (M = Cd, Zn) with different starting Al/Cr molar ratios and nitrate/carbonate as the interlayer anion have been prepared following the coprecipitation method at a constant pH: Zn{sup II}-Al{sup III}-Cr{sup III}-CO{sub 3}{sup 2-} at pH = 10, and Cd{sup II}-Al{sup III}-Cr{sup III}-NO{sub 3}{sup -} at pH = 8. Two additional M{sup II},Al{sup III}-LDH samples (M = Cd, Zn) with chromate ions (CrO{sub 4}{sup 2-}) in the interlayer have been prepared by ionic exchange at pH = 9 and 8, respectively, starting from M{sup II}-Al{sup III}-NO{sub 3}{sup -}. The samples have been characterised by absorption atomic spectrometry, powder X-ray diffraction (PXRD), FT-IR spectroscopy and transmission electron microscopy (TEM). Their thermal stability has been assessed by DTA-TG and mass spectrometric analysis of the evolved gases. The PXRD patterns of the solids calcined at 800 Degree-Sign C show diffraction lines corresponding to ZnO and ZnAl{sub 2-x}Cr{sub x}O{sub 4} for the Zn-containing samples, and diffraction lines attributed to CdO and CdCr{sub 2}O{sub 4} and (Al,Cr){sub 2}O{sub 3} for the Cd-containing ones. Additionally a minority oxide, Cd{sub 2}CrO{sub 5}, is observed to Cd{sup II}-Al{sup III

The influences of Al content on the microstructure and mechanical properties of as-cast Mg-6Zn magnesium alloys

International Nuclear Information System (INIS)

Zhang, Yu; Huang, Xiaofeng; Ma, Zhenduo; Li, Ya; Guo, Feng; Yang, Jianchang; Ma, Ying; Hao, Yuan

2017-01-01

Mg-6Zn magnesium alloys microalloyed with varying Al content (0, 1, 3, 5 and 7 wt%) were prepared by permanent mould casting. The effects of Al on the microstructure and mechanical properties of as-cast Mg-6Zn alloy were characterized with an optical microscope (OM), a scanning electron microscope (SEM) equipped with energy dispersive spectroscope (EDS), an X-ray diffractometer (XRD) and mechanical tests at room temperature, respectively. The experimental results indicate that the grain sizes do not decline obviously while the amount of eutectic phase and the secondary dendrite arm spacing (SDAS) of the alloys gradually increase when the Al content exceeds 3%. The main phases α-Mg, MgZn 2 , Mg 2 Zn 3 , Mg 7 Zn 3 , MgZn, Mg 32 (Al, Zn) 49 and Mg 17 Al 12 are found in these alloys. A higher addition of Al (≥5 wt%) causes the formation of the Mg 17 Al 12 , meanwhile, the partial morphology of some eutectic phases is modified into lamellar formation, which has an adverse effect on mechanical properties of the Al-containing alloys. The mechanical testing reveals that, the tensile properties are gradually improved within the range of 0 ~ 3%Al, and the maximum values of ultimate tensile strength (UTS, 214 MPa) and elongation (EL, 8.7%) are simultaneously obtained from the alloy with 3% Al, which increases by 21 MPa and 16.0% compared with that of the ZA60 alloy, respectively. Fracture analysis demonstrates that quasi-cleavage fracture, inter-granular and trans-granular fracture are dominant modes in the alloy with additions of 0, 1, 3 wt% Al. In contrast, the rupture mechanisms of the other investigated alloys belong to cleavage and inter-granular fracture modes.

The influences of Al content on the microstructure and mechanical properties of as-cast Mg-6Zn magnesium alloys

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yu; Huang, Xiaofeng, E-mail: huangxf_lut@163.com; Ma, Zhenduo; Li, Ya; Guo, Feng; Yang, Jianchang; Ma, Ying; Hao, Yuan

2017-02-16

Mg-6Zn magnesium alloys microalloyed with varying Al content (0, 1, 3, 5 and 7 wt%) were prepared by permanent mould casting. The effects of Al on the microstructure and mechanical properties of as-cast Mg-6Zn alloy were characterized with an optical microscope (OM), a scanning electron microscope (SEM) equipped with energy dispersive spectroscope (EDS), an X-ray diffractometer (XRD) and mechanical tests at room temperature, respectively. The experimental results indicate that the grain sizes do not decline obviously while the amount of eutectic phase and the secondary dendrite arm spacing (SDAS) of the alloys gradually increase when the Al content exceeds 3%. The main phases α-Mg, MgZn{sub 2}, Mg{sub 2}Zn{sub 3}, Mg{sub 7}Zn{sub 3}, MgZn, Mg{sub 32}(Al, Zn){sub 49} and Mg{sub 17}Al{sub 12} are found in these alloys. A higher addition of Al (≥5 wt%) causes the formation of the Mg{sub 17}Al{sub 12}, meanwhile, the partial morphology of some eutectic phases is modified into lamellar formation, which has an adverse effect on mechanical properties of the Al-containing alloys. The mechanical testing reveals that, the tensile properties are gradually improved within the range of 0 ~ 3%Al, and the maximum values of ultimate tensile strength (UTS, 214 MPa) and elongation (EL, 8.7%) are simultaneously obtained from the alloy with 3% Al, which increases by 21 MPa and 16.0% compared with that of the ZA60 alloy, respectively. Fracture analysis demonstrates that quasi-cleavage fracture, inter-granular and trans-granular fracture are dominant modes in the alloy with additions of 0, 1, 3 wt% Al. In contrast, the rupture mechanisms of the other investigated alloys belong to cleavage and inter-granular fracture modes.

Synthesis and characterization of Fullerene modified ZnAlTi-LDO in photo-degradation of Bisphenol A under simulated visible light irradiation

International Nuclear Information System (INIS)

Ju, Liting; Wu, Pingxiao; Lai, Xiaolin; Yang, Shanshan; Gong, Beini; Chen, Meiqing

2017-01-01

In this study, ZnAlTi layered double hydroxide (ZnAlTi-LDH) combined with fullerene (C 60 ) was fabricated by the urea method, and calcined under vacuum atmosphere to obtain nanocomposites of C 60 -modified ZnAlTi layered double oxide (ZnAlTi-LDO). The morphology, structure and composition of the nanocomposites were analyzed by Scanning Electron Microscopy, High-resolution transmission electron microscopy, X-ray diffraction patterns, Fourier transform infrared and specific surface area. The UV-vis diffuse reflectance spectra indicated that the incorporation of C 60 expanded the absorption of ZnAlTi-LDO to visible-light region. The photo-degradation experiment was conducted by using a series of C 60 modified ZnAlTi-LDO with different C 60 weight percentage to degrade Bisphenol A (BPA) under simulated visible light irradiation. In this experiment, the degradation rate of C 60 modified ZnAlTi-LDO in photo-degradation of BPA under simulated visible light irradiation was over 80%. The intermediates formed in the degradation of BPA process by using LDO/C 60 -5% were 4-hydroxyphenyl-2-propanol, 4-isopropenylphenol and Phenol. Photogenerated holes, superoxide radical species, ·OH and singlet oxygen were considered to be responsible for the photodegradation process, among which superoxide radical species and ·OH played a predominant role in the photocatalytic reaction system. C 60 modified ZnAlTi-LDO catalysts for photocatalytic reduction shows great potential in degradation of organic pollutants and environmental remediation. - Highlights: • C 60 modified ZnAlTi-LDO enhance the photocatalytic reduction of BPA. • C 60 modified ZnAlTi-LDO was an efficient photocatalytic in the degradation of BPA under visible light. • Superoxide radical species played a predominant role in the photocatalytic reaction system. • C 60 expanded the absorption of ZnAlTi-LDO to visible-light region with the increasing content of C 60 .

Effect of wrapped Zn plate on the densification of Al-MWCNTs composites produced by cold pressing and liquid phase sintering

Energy Technology Data Exchange (ETDEWEB)

Joo, M.R. [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Choi, H.J. [School of Advanced Materials Engineering, Kookmin University, Seoul 136-702 (Korea, Republic of); Shin, S.E. [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Bae, D.H., E-mail: donghyun@yonsei.ac.kr [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)

2016-09-30

To produce highly dense and cost-effective Al-multi-walled carbon nanotube (Al-MWCNT) composites, the composite powders are wrapped by a Zn plate and then cold-pressed. The green compacts are then sintered at 550 °C, which shows ~99%density after sintering for 24 h. During sintering, Zn atoms fill the voids at the powder boundaries by capillary action and are then dissolved into the Al matrix because of the high solubility of Zn in Al, thus assisting densification of the composite powder. The Al/Zn-based composites containing 4 vol% MWCNTs show compressive yield strength (~380 MPa) and high work hardening capacity.

A simple method to prepare ZnO and Al(OH)3 nanorods by the reaction of the metals with liquid water

International Nuclear Information System (INIS)

Panchakarla, L.S.; Shah, M.A.; Govindaraj, A.; Rao, C.N.R.

2007-01-01

Reaction of liquid water with Zn and Al powders and foils have been investigated in the 25-75 deg. C range. The reaction of Zn metal powder with water in this temperature range yields ZnO nanorods. The diameter of the nanorods decreases slightly with the increase in the reaction temperature, accompanied by an increase in the relative intensity of UV emission band. Zn metal foils also yield ZnO nanorods on reaction with water in the 25-75 deg. C range. Reaction of Al metal powder or foil with water in the 25-75 deg. C range yields Al(OH) 3 nanorods. The formation of ZnO and Al(OH) 3 nanorods by the reaction of the metals with water is suggested to occur because of the decomposition of water by the metal giving hydrogen. - Graphical abstract: The reaction of water at a temperature in the 25-27 deg. C range with zinc metal gives rise to ZnO nanorods; with Al metal water gives Al(OH) 3 nanorods

ANTS-anchored Zn-Al-CO{sub 3}-LDH particles as fluorescent probe for sensing of folic acid

Energy Technology Data Exchange (ETDEWEB)

Liu, Pengfei; Liu, Dan; Liu, Yanhuan [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Key Laboratory of Environmentally Harmful Chemical Analysis, Beijing University of Chemical Technology, Beijing 100029 (China); Li, Lei, E-mail: lilei@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Key Laboratory of Environmentally Harmful Chemical Analysis, Beijing University of Chemical Technology, Beijing 100029 (China)

2016-09-15

A novel fluorescent nanosensor for detecting folic acid (FA) in aqueous media has been developed based on 8-aminonaphthalene-1,3,6-trisulfonate (ANTS) anchored to the surface of Zn-Al-CO{sub 3}-layered double hydroxides (LDH) particles. The nanosensor showed high fluorescence intensity and good photostability due to a strong coordination interaction between surface Zn{sup 2+} ions of Zn-Al-CO{sub 3}-LDH and N atoms of ANTS, which were verified by result of X-ray photoelectron spectroscopy (XPS). ANTS-anchored on the surface of Zn-Al-CO{sub 3}-LDH restricted the intra-molecular rotation leading to ANTS-anchored J-type aggregation emission enhancement. ANTS-anchored Zn-Al-CO{sub 3}-LDH particles exhibited highly sensitive and selective response to FA over other common metal ions and saccharides present in biological fluids. The proposed mechanism was that oxygen atoms of -SO{sub 3} groups in ANTS-anchored on the surface of Zn-Al-CO{sub 3}-LDH were easily collided by FA molecules to form potential hydrogen bonds between ANTS-anchored and FA molecules, which could effectively quench the ANTS-anchored fluorescence. Under the simulated physiological conditions (pH of 7.4), the fluorescence quenching was fitted to Stern-Volmer equation with a linear response in the concentration range of 1 μM to 200 μM with a limit of detection of 0.1 μM. The results indicate that ANTS-anchored Zn-Al-CO{sub 3}-LDH particles can afford a very sensitive system for the sensing FA in aqueous solution. - Highlights: • A novel fluorescent nanosensor has been developed. • The sensor exhibited highly sensitive and selective response to FA. • The fluorescence quenching was fitted to Stern–Volmer equation. • The linear response range was 1–200 μM with a limit of detection of 0.1 μM.

Emergent ferromagnetism in ZnO/Al2O3 core-shell nanowires: Towards oxide spinterfaces

KAUST Repository

Xing, G. Z.; Wang, D. D.; Cheng, C.-J.; He, M.; Li, S.; Wu, Tao

2013-01-01

We report that room-temperature ferromagnetism emerges at the interface formed between ZnO nanowire core and Al2O3 shell although both constituents show mainly diamagnetism. The interface-based ferromagnetism can be further enhanced by annealing the ZnO/Al2O3 core-shell nanowires and activating the formation of ZnAl2O4 phase as a result of interfacial solid-state reaction. High-temperature measurements indicate that the magnetic order is thermally stable up to 750 K. Transmission electron microscopy studies reveal the annealing-induced jagged interfaces, and the extensive structural defects appear to be relevant to the emergent magnetism. Our study suggests that tailoring the spinterfaces in nanostructure-harnessed wide-band-gap oxides is an effective route towards engineered nanoscale architecture with enhanced magnetic properties.

Emergent ferromagnetism in ZnO/Al2O3 core-shell nanowires: Towards oxide spinterfaces

KAUST Repository

Xing, G. Z.

2013-07-08

We report that room-temperature ferromagnetism emerges at the interface formed between ZnO nanowire core and Al2O3 shell although both constituents show mainly diamagnetism. The interface-based ferromagnetism can be further enhanced by annealing the ZnO/Al2O3 core-shell nanowires and activating the formation of ZnAl2O4 phase as a result of interfacial solid-state reaction. High-temperature measurements indicate that the magnetic order is thermally stable up to 750 K. Transmission electron microscopy studies reveal the annealing-induced jagged interfaces, and the extensive structural defects appear to be relevant to the emergent magnetism. Our study suggests that tailoring the spinterfaces in nanostructure-harnessed wide-band-gap oxides is an effective route towards engineered nanoscale architecture with enhanced magnetic properties.

Zn-Al LAYERED DOUBLE HYDROXIDE PILLARED BY DIFFERENT DICARBOXYLATE ANIONS

Directory of Open Access Journals (Sweden)

S. Gago

2004-12-01

Full Text Available Zn-Al layered double hydroxides (LDHs intercalated by terephthalate (TPH and biphenyl-4,4'-dicarboxylate (BPH anions have been synthesized by direct co-precipitation from aqueous solution. The Zn/Al ratio in the final materials was 1.8. The products were characterized by powder X-ray diffraction, thermogravimetric analysis, FTIR and FT Raman spectroscopy, and MAS NMR spectroscopy. The basal spacing for the TPH-LDH intercalate was 14.62 Å, indicating that the guest anions stack to form a monolayer with the aromatic rings perpendicular to the host layers. For the LDH intercalate containing BPH anions, a basal spacing of at least 19.2 Å would be expected if the anions adopted an arrangement similar to that for the TPH anions. The observed spacing was 18.24 Å, suggesting that the anions are tilted slightly with respect to the host layers.

Growth and characterization of Ag/n-ZnO/p-Si/Al heterojunction diode by sol–gel spin technique

International Nuclear Information System (INIS)

Keskenler, E.F.; Tomakin, M.; Doğan, S.; Turgut, G.; Aydın, S.; Duman, S.; Gürbulak, B.

2013-01-01

Highlights: ► Ag/n-ZnO/p-Si/Al heterojunction diode was grown via sol–gel technique. ► The characterization of ZnO material was investigated. ► The heterojunction structure showed a rectification behavior. ► Ideality factor and barrier height were found to be 2.03 and 0.71 eV, respectively. - Abstract: Polycrystalline ZnO thin film was obtained on the p-Si for the heterojunction diode fabrication by sol–gel method. X-ray diffraction study showed that the texture of the film is hexagonal with a strong (0 0 2) preferred direction. Scanning electron microscope image of ZnO showed that the obtained ZnO thin films had more porous character. High purity vacuum evaporated silver (Ag) and aluminum (Al) metals were used to make Ohmic contacts to the n-ZnO/p-Si heterojunction structure. The electrical properties of Ag/n-ZnO/p-Si/Al diode were investigated by using current–voltage measurements. Ag/n-ZnO/p-Si/Al heterojunction diode showed a rectification behavior, and its ideality factor and barrier height values were found to be 2.03 and 0.71 eV by applying a thermionic emission theory, respectively. The values of series resistance from dV/d (ln I) versus I and H(I) versus I curves were found to be 42.1 and 198.3 Ω, respectively.

Zn/55Al coating microstructure and corrosion mechanism

International Nuclear Information System (INIS)

Moreira, A. Ramus; Panossian, Z.; Camargo, P.L.; Moreira, M. Ferreira; Silva, I.C. da; Ribeiro de Carvalho, J.E.

2006-01-01

In the present work Zn/55Al coatings from different suppliers were studied. The results revealed the presence of at least two different phases in the interdendritic and in the dendritic areas that compose the coating. Analyses done in the cross section of test panels exposed for five years in six different atmospheres showed that the corrosion process begins in the aluminium-rich phase present in the interdendritic area

Charge transfer-type fluorescence of Ti-doped Ca{sub 14}Al{sub 10}Zn{sub 6}O{sub 35}

Energy Technology Data Exchange (ETDEWEB)

Satoh, Yuta; Takemoto, Minoru, E-mail: takemoto@chem.kanagawa-it.ac.jp

2017-05-15

The calcium aluminum zincates Ca{sub 14}(Al{sub 1-2x}Ti{sub x}Zn{sub x}){sub 10}Zn{sub 6}O{sub 35}, in which Al{sup 3+} sites in the host material Ca{sub 14}Al{sub 10}Zn{sub 6}O{sub 35} are simultaneously substituted by Ti{sup 4+} and Zn{sup 2+}, were synthesized by a polymerized complex method. Al{sup 3+} ions could be replaced up to an x value of 0.1. The host material does not exhibit fluorescence, while the cation-substituted samples show an emission band centered at 383 nm under excitation by UV light at 243 nm. The emission intensity increases with x up to 0.1 and then gradually decreases as x is further increased. The emission wavelength also becomes longer with increasing temperature. Based on the properties of other Ti{sup 4+}-containing fluorescent materials, the emission of Ca{sub 14}(Al{sub 1-2x}Ti{sub x}Zn{sub x}){sub 10}Zn{sub 6}O{sub 35} is attributed to charge transfer-type fluorescence resulting from [TiO{sub 6}] octahedra.

Microstructure and characterization of Al-doped ZnO films prepared by RF power sputtering on Al and ZnO targets

Energy Technology Data Exchange (ETDEWEB)

Tseng, Chun-An [Department of Mechanical Engineering, National Central University, Taiwan (China); Lin, Jing-Chie, E-mail: jclincom@cc.ncu.edu.tw [Department of Mechanical Engineering, National Central University, Taiwan (China); Institute of Material Science and Engineering, National Central University, Taiwan (China); Chang, Yu-Fong [Department of Mechanical Engineering, National Central University, Taiwan (China); Chyou, San-Der [Power Research Institute, Taiwan Power Company, Taiwan (China); Peng, Kun-Cheng [Department of Materials Science and Engineering, Mingchi University of Technology, Taiwan (China)

2012-06-01

Al-doped zinc oxide (AZO) transparent conductive films were prepared on a glass substrate using a magnetron sputtering system with a pure zinc oxide (ZnO) target and a pure Al target sputtered using radio frequency (RF) power. The RF power was set at 100 W for the ZnO target and varied from 20 to 150 W for the Al target. The morphology of the thin films was examined by field-emission scanning electron microscope (FE-SEM), and their composition was analyzed by the equipped energy-dispersive X-ray spectroscopy (EDS). The cross section of the films determined through FE-SEM indicated that their thickness was around 650 nm. EDS analysis revealed that the Al-dopant concentration of the AZO films increased in the following order: 0.85 at.% (20 W) < 1.60 at.% (40 W) < 3.52 at.% (100 W) < 4.34 at.% (150 W). Analysis of the films using X-ray diffractometer (XRD) indicated that all films had a wurtzite structure with a texture of (0 0 2). High-resolution transmission electron microscopy (HRTEM) revealed a number of defects in the films, such as stacking faults and dislocations. Ultraviolet photoelectron spectroscopy (UPS) was used to estimate the optical energy gap (E{sub g}) for the AZO thin films. The energy gap increases from 3.39 to 3.58 eV as the RF power applied to the Al target increase. The electrical resistivity of the films decreased from 3.43 Multiplication-Sign 10{sup -2} {Omega} cm to 3.29 Multiplication-Sign 10{sup -3} {Omega} cm as the RF power increased from 20 to 150 W when a four-point probe was used to investigate. Atomic force microscope (AFM) revealed that the surface roughness of the films increased with increasing RF power. The average optical transmittance of the films was determined by UV-visible spectrometer. The films are suitable for use as transparent conductive oxide films in the optoelectronic industry. A decrease in the electrical resistivity of the film with increasing Al-dopant concentration was ascribed to an increase in the carrier

Ab-initio valence band spectra of Al, In doped ZnO

International Nuclear Information System (INIS)

Palacios, P.; Sanchez, K.; Wahnon, P.

2009-01-01

We present the structural and electronic characterization of n-doped (Aluminium or Indium) ZnO and the effect of the doping on the calculated photoelectron spectroscopy (PES) spectra. The fully-relaxed calculations have been made using the density functional theory, including a Hubbard correlation term that increases the Zn-3d states binding energy, and which matches the experimental values. The effect of Oxygen vacancies is also included in our study. Our results show that the new Al or In-donor levels appearing in the conduction band hybridize with the Oxygen-2p states and help decrease the resistivity of these doped systems as was found experimentally. The calculated PES spectra show a small enhancement in the intensity close to the chemical potential as a result of these new Al or In levels

A novel fabrication of MEH-PPV/Al:ZnO nanorod arrays based ordered bulk heterojunction hybrid solar cells

Energy Technology Data Exchange (ETDEWEB)

Malek, M.F., E-mail: firz_solarzelle@yahoo.com [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Sahdan, M.Z.; Mamat, M.H.; Musa, M.Z. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Khusaimi, Z.; Husairi, S.S. [NANO-SciTech Centre (NST), Institute of Science (IOS), Universiti Teknologi MARA -UiTM, 40450 Shah Alam, Selangor (Malaysia); Md Sin, N.D. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Rusop, M. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), Institute of Science (IOS), Universiti Teknologi MARA - UiTM, 40450 Shah Alam, Selangor (Malaysia)

2013-06-15

Vertically aligned Al:ZnO nanorod arrays has been used as window layer in the fabrication of ordered bulk heterojuction hybrid solar cells. The utilization of the nanorod arrays will enhance the electron transport in vertical direction and also for light harvesting applications for high performance devices. The performance of this hybrid polymer/metal oxide photovoltaic devices based on MEH-PPV [poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene)] and oriented Al:ZnO nanorod arrays is studied. The Al:ZnO nanorod arrays with a diameter of about 70–80 nm and thickness of approximately 500 nm were successfully grown on Al:ZnO-coated ITO substrate by sonicated sol–gel immersion technique. The photovoltaic performance of a short-circuit current density of 5.320 mA/cm{sup 2}, an open-circuit voltage of 195 mV and a fill factor of 27.71%, with a power conversion efficiency of about 0.287% under AM 1.5 illumination (100 mW/cm{sup 2}). To the best of our knowledge, preparation of aligned Al:ZnO nanorod arrays for this type of solar cell fabrication has not been reported by any research group.

Investigation on thermo physical characteristics of ethylene glycol based Al:ZnO nanofluids

International Nuclear Information System (INIS)

Kiruba, R.; George, Ritty; Gopalakrishnan, M.; Kingson Solomon Jeevaraj, A.

2015-01-01

The present work describes the experimental aspects of viscosity and thermal conductivity characteristics of nanofluids. Aluminium doped zinc oxide nanostructures were synthesized by chemical precipitation method. Ultrasonic technique is used to disperse the nanostructures in ethylene glycol. Structural and morphological properties of Al doped ZnO nanostructures are characterized using X-ray diffractometer and scanning electron microscopic technique. The effect of concentration and temperature on thermo-physical properties of Al/ZnO nanofluids is also investigated. The experimental results showed there is enhancement in thermal conductivity with rise in temperature which can be utilized for coolant application

Origin of intragranular crystallographic misorientations in hot-dip Al-Zn-Si coatings

International Nuclear Information System (INIS)

Niederberger, Ch.; Michler, J.; Jacot, A.

2008-01-01

The origin of intragranular variations of the crystallographic orientation in hot-dip Al-Zn-Si coatings is discussed based on new experimental results and modelling. The solidification microstructure in as-received 55Al-43.4Zn-1.6Si (in wt.%) coatings deposited on steel plates in an industrial production line was analyzed by electron backscattered diffraction, glow-discharge optical emission spectroscopy and atomic force microscopy (AFM). The results were compared with those obtained in coatings re-solidified under different cooling and mechanical loading conditions. Continuous variations of the crystallographic orientation as large as 35 deg. were observed within individual grains of Al-Zn-Si, consistent with previous studies. However, the mechanisms previously proposed for the origin of intragranular crystallographic misorientations had to be revisited. The new experimental data acquired during this study indicate that the solidification shrinkage accumulating in the area of the grain envelope is the driving force for the formation of intragranular misorientations. The solidification shrinkage leads to the development of tensile stresses in the oxide film covering the coating while it solidifies. Estimations based on AFM profiles and phase field simulations of the dendritic structure indicate that the stresses applied on the dendrite network are sufficient to deform plastically the dendrite arms during solidification

Urea biosensor based on Zn3Al-Urease layered double hydroxides nanohybrid coated on insulated silicon structures

International Nuclear Information System (INIS)

Barhoumi, H.; Maaref, A.; Rammah, M.; Martelet, C.; Jaffrezic, N.; Mousty, C.; Vial, S.; Forano, C.

2006-01-01

Urea biosensors for medical diagnostic monitoring were developed based on the immobilization of urease within layered double hydroxides (LDH). The urease-LDH material was obtained by a stepwise exchange reaction by urease of a Zn 3 Al-dodecyl sulphate (ZnAl-DS) colloidal suspension. XR diffraction and FTIR analysis show that this method gives rise to a Zn 3 Al-Urease LDH nanohybrid material with urease dispersion and textural properties. An aqueous suspension of this urease-LDH nanohybrid material was deposited on an insulated semiconductor (IS) structure. Biosensor responses to urea additions were obtained using capacitance (C vs. V) and impedance (Z vs. ω) measurements. An enhanced maximum limit of the dynamic range was observed in the case of the impedance measurements (110 mM) compared to (5.6 mM) the capacitive urea biosensor. The Michaelis-Menten constant was also calculated according to the Lineweaver-Burk plot. It was found that the K m value with immobilized enzymes was lower (K m = 0.67 mM) in comparison with free enzymes. This K m value obtained from the capacitance measurements indicates that the urea degradation is performed within any inhibition action on the IS/Zn 3 Al-Urease LDH electrode. A comparative study was carried out between these results and those obtained previously, using urease/ZnAl-Cl layered double hydroxides mixture coated on the pH-ISFET transducer

Hume-Rothery electron concentration rule across a whole solid solution range in a series of gamma-brasses in Cu-Zn, Cu-Cd, Cu-Al, Cu-Ga, Ni-Zn and Co-Zn alloy systems

Science.gov (United States)

Mizutani, U.; Noritake, T.; Ohsuna, T.; Takeuchi, T.

2010-05-01

The aim of the present work is to examine if the Hume-Rothery stabilisation mechanism holds across whole solid solution ranges in a series of gamma-brasses with especial attention to the role of vacancies introduced into the large unit cell. The concentration dependence of the number of atoms in the unit cell, N, for gamma-brasses in the Cu-Zn, Cu-Cd, Cu-Al, Cu-Ga, Ni-Zn and Co-Zn alloy systems was determined by measuring the density and lattice constants at room temperature. The number of itinerant electrons in the unit cell, e/uc, is evaluated by taking a product of N and the number of itinerant electrons per atom, e/a, for the transition metal element deduced earlier from the full-potential linearised augmented plane wave (FLAPW)-Fourier analysis. The results are discussed within the rigid-band model using as a host the density of states (DOS) derived earlier from the FLAPW band calculations for the stoichiometric gamma-brasses Cu5Zn8, Cu9Al4 and TM2Zn11 (TM = Co and Ni). A solid solution range of gamma-brasses in Cu-Zn, Cu-Cd, Cu-Al, Cu-Ga and Ni-Zn alloy systems is found to fall inside the existing pseudogap at the Fermi level. This is taken as confirmation of the validity of the Hume-Rothery stability mechanism for a whole solute concentration range of these gamma-brasses. An exception to this behaviour was found in the Co-Zn gamma-brasses, where orbital hybridisation effects are claimed to play a crucial role in stabilisation.

Transparent capacitors with hybrid ZnO:Al and Ag nanowires as electrodes

International Nuclear Information System (INIS)

Zhang, Guozhen; Wu, Hao; Wang, Xiao; Wang, Ti; Liu, Chang

2016-01-01

Transparent conducting films with a composite structure of AlZnO–Ag nanowires (AgNWs) have been prepared by atomic layer deposition. The sheet resistance was reduced from 120 to 9 Ω when the AgNW networks were involved. Transparent capacitors with Al_2O_3–TiO_2–Al_2O_3 dielectrics were fabricated on the composite electrodes and demonstrated a capacitance density of 10.1 fF μm"−"2, which was significantly higher than that of capacitors with AlZnO electrodes (8.8 fF μm"−"1). The capacitance density remained almost unchanged in a broad frequency range from 3 kHz to 1 MHz. Moreover, a low leakage current density of 2.4 × 10"−"7 A cm"−"2 at 1 V was achieved. Transparent and flexible capacitors were also fabricated using the composite electrodes, and demonstrated an improved bendability. The transparent capacitors showed an average optical transmittance over 70% in the visible range, and thus open the door to practical applications in transparent integrated circuits. (paper)

Precipitation in an Al-Zn-Mg-Cu alloy during isothermal aging: Atomic-scale HAADF-STEM investigation

Energy Technology Data Exchange (ETDEWEB)

Xu, Xuesong; Zheng, Jingxu; Li, Zhi; Luo, Ruichun [School of Materials Science and Engineering, Shanghai Jiao Tong University (China); Frontier Research Center for Materials Structure, Shanghai Jiao Tong University (China); Chen, Bin, E-mail: steelboy@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University (China); Frontier Research Center for Materials Structure, Shanghai Jiao Tong University (China)

2017-04-13

The present study, using advanced Cs-corrected high-angle annular dark field – scanning transmission electron microscopy (HAADF-STEM), reports on a comprehensive investigation into the precipitate structures in an Al-Zn-Mg-Cu alloy aged at 150 ℃, including GP zones, η’ and η precipitates. In the nucleation stage, Zn atoms enrich on the {111}{sub Al}-planes abutting spherical Mg clusters that are approximately 3–6 nm in diameter. In the subsequent growth, the as-nucleated structures extend with an increasing diameter and a constant width along [111]{sub Al} and grow into platelet precipitates. η’ is proved to be a group of metastable structures existing in the transition from FCC Al to HCP MgZn{sub 2} (η). Some metastable structures are assembled by local-ordered rhombohedral units and orthorhombic units as building blocks. Subsequently, the precipitates evolve into η phases with stacking faults.

The in vitro biocompatibility and macrophage phagocytosis of Mg17Al12 phase in Mg-Al-Zn alloys.

Science.gov (United States)

Liu, Chen; He, Peng; Wan, Peng; Li, Mei; Wang, Kehong; Tan, Lili; Zhang, Yu; Yang, Ke

2015-07-01

Mg alloys are gaining interest for applications as biodegradable medical implant, including Mg-Al-Zn series alloys with good combination of mechanical properties and reasonable corrosion resistance. However, whether the existence of second phase particles in the alloys exerts influence on the biocompatibility is still not clear. A deeper understanding of how the particles regulate specific biological responses is becoming a crucial requirement for their subsequent biomedical application. In this work, the in vitro biocompatibility of Mg17Al12 as a common second phase in biodegradable Mg-Al-Zn alloys was investigated via hemolysis, cytotoxicity, cell proliferation, and cell adhesion tests. Moreover, osteogenic differentiation was evaluated by the extracellular matrix mineralization assay. The Mg17Al12 particles were also prepared to simulate the real situation of second phase in the in vivo environment in order to estimate the cellular response in macrophages to the Mg17Al12 particles. The experimental results indicated that no hemolysis was found and an excellent cytocompatibility was also proved for the Mg17Al12 second phase when co-cultured with L929 cells, MC3T3-E1 cells and BMSCs. Macrophage phagocytosis co-culture test revealed that Mg17Al12 particles exerted no harmful effect on RAW264.7 macrophages and could be phagocytized by the RAW264.7 cells. Furthermore, the possible inflammatory reaction and metabolic way for Mg17Al12 phase were also discussed in detail. © 2014 Wiley Periodicals, Inc.

Corrosion mechanism of Al, Al–Zn and Al–Zn–Sn alloys in 3 wt.% NaCl solution

International Nuclear Information System (INIS)

Khireche, S.; Boughrara, D.; Kadri, A.; Hamadou, L.; Benbrahim, N.

2014-01-01

Highlights: • We elaborate Al–5Zn–xSn sacrificial anodes (x = 0.1%, 0.2% and 0.4%). • Increasing Sn amount does activate Al alloys. • The anode dissolution in NaCl initiates at precipitations where Sn is enriched. • Sn enhances uniform attack on the surface of the Al alloy. • Al–Zn–Sn anodes perform better than the Al–Zn anode. - Abstract: The effect of zinc and tin addition to pure aluminum was investigated in 3 wt.% NaCl solution. The corrosion behavior of the elaborated samples (Al, Al–Zn and Al–Zn–Sn) was studied by open circuit potential, Tafel plot and electrochemical impedance spectroscopy. For the microstructure characterization, Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy were used. The aluminum activation increases in the following order: Al < Al–5Zn < Al–5Zn–0.1Sn < Al–5Zn–0.2Sn < Al–5Zn–0.4Sn. The impedance measurements and the microscopic observations confirmed the great activity of Al–Zn and Al–Zn–Sn compared to pure Al. The segregation at the grain boundaries leads to intergranular corrosion

Directional solidification of Zn-Al-Cu eutectic alloy by the vertical Bridgman method

Directory of Open Access Journals (Sweden)

Büyük U.

2015-01-01

Full Text Available In the present work, the effect of growth rate and temperature gradient on microstructure and mechanical properties of Zn-7wt.%Al-4wt.%Cu eutectic alloy has been investigated. Alloys prepared under steady-state conditions by vacuumed hot filing furnace. Then, the alloys were directionally solidified upward with different growth rates (V=11.62-230.77 mm/s at a constant temperature gradient (G=7.17 K/mm and with different temperature gradients (G=7.17-11.04 K/mm at a constant growth rate (V=11.62 mm/s by a Bridgman furnace. The microstructures were observed to be lamellae of Zn, Al and broken lamellae CuZn4 phases from quenched samples. The values of eutectic spacing, microhardness and ultimate tensile strength of alloys were measured. The dependency of the microstructure and mechanical properties on growth rate and temperature gradient were investigated using regression analysis.

Effects of boron and aging on mechanical properties and martensitic temperatures in Cu-Zn-Al shape-memory alloys

International Nuclear Information System (INIS)

Han, Y.S.; Kim, Y.G.

1987-01-01

This work is concerned with the effects of added boron (0.1 w/o) on mechanical properties and martensitic transformation temperatures (Ms) of the Cu - 14.0 Zn - 8.5. Al shape memory alloy. The composition was designed to have Ms temperature in the vicinity of 100 0 C. The influence of applying step quenching on the variation in Ms temperatures has been studied in boron-free Cu - 14.0 Zn - 8.5 Al and boron-containing Cu - 14.0 Zn 8.5 Al - 0.1 B alloys. Aging kinetics and transformation temperatures have been determined by electrical resistivity measurements

Understanding corrosion via corrosion product characterization: II. Role of alloying elements in improving the corrosion resistance of Zn-Al-Mg coatings on steel

International Nuclear Information System (INIS)

Volovitch, P.; Vu, T.N.; Allely, C.; Abdel Aal, A.; Ogle, K.

2011-01-01

Highlights: → Origins of better corrosion resistance of ZnAlMg coatings than galvanized steel. → Comparative study of corrosion products formed on ZnAlMg, ZnMg and Zn coatings. → Modeling of dissolution and precipitation stages of corrosion. → At early stages Mg stabilizes protective zinc basic salts during dry-wet cycling. → At later stages Al dissolves at high pH forming protective layered double hydroxides. - Abstract: Corrosion products are identified on Zn, ZnMg and ZnAlMg coatings in cyclic corrosion tests with NaCl or Na 2 SO 4 containing atmospheres. For Mg-containing alloys the improved corrosion resistance is achieved by stabilization of protective simonkolleite and zinc hydroxysulfate. At later stages, the formation of layered double hydroxides (LDH) is observed for ZnAlMg. According to thermodynamic modeling, Mg 2+ ions bind the excess of carbonate or sulfate anions preventing the formation of soluble or less-protective products. A preferential dissolution of Zn and Mg at initial stages of corrosion is confirmed by in situ dissolution measurement. The physicochemical properties of different corrosion products are compared.

Genesis of flake-like morphology and dye-sensitized solar cell performance of Al-doped ZnO particles: a study

International Nuclear Information System (INIS)

Sengupta, D.; Mondal, B.; Mukherjee, K.

2017-01-01

In dye-sensitized solar cell (DSSC) application, the particulate morphologies of photo-anode facilitate efficient dye loading and thus lead to better photo-conversion efficiency than their thin film counterpart. However, till date, the electronic and optical properties as well as the DSSC application of Al-doped ZnO (AZO) particles as photo-anode material is studied less than thin films. Herein, phase formation behavior, morphology evolution, optical properties, and dye-sensitized solar cell performance of wet chemically prepared ZnO and AZO (dopant level: 1–4 mol%) particles are studied. It is found that Al doping modulates significantly the ZnO morphology which in turn results the maximum dye adsorption as well as best photo-conversion efficiency at optimum dopant concentration. Specifically, the nanoparticle of ZnO turns predominantly to flake-like morphology with a higher surface area when 2 mol% Al is doped. Such morphology modulation is expected, since the crystallinity, lattice parameters, and lattice strain of ZnO changes appreciably with Al doping. The variations of optical properties (absorbance, diffused reflectance, and band gap) of AZO materials as compared to primitive ZnO are also identified through UV-vis studies. An attempt is made here to correlate the structural features with the photovoltaic performances of ZnO and AZO.

Genesis of flake-like morphology and dye-sensitized solar cell performance of Al-doped ZnO particles: a study

Energy Technology Data Exchange (ETDEWEB)

Sengupta, D.; Mondal, B.; Mukherjee, K., E-mail: kalisadhanm@yahoo.com [CSIR-Central Mechanical Engineering Research Institute, Centre for Advanced Materials Processing (India)

2017-03-15

In dye-sensitized solar cell (DSSC) application, the particulate morphologies of photo-anode facilitate efficient dye loading and thus lead to better photo-conversion efficiency than their thin film counterpart. However, till date, the electronic and optical properties as well as the DSSC application of Al-doped ZnO (AZO) particles as photo-anode material is studied less than thin films. Herein, phase formation behavior, morphology evolution, optical properties, and dye-sensitized solar cell performance of wet chemically prepared ZnO and AZO (dopant level: 1–4 mol%) particles are studied. It is found that Al doping modulates significantly the ZnO morphology which in turn results the maximum dye adsorption as well as best photo-conversion efficiency at optimum dopant concentration. Specifically, the nanoparticle of ZnO turns predominantly to flake-like morphology with a higher surface area when 2 mol% Al is doped. Such morphology modulation is expected, since the crystallinity, lattice parameters, and lattice strain of ZnO changes appreciably with Al doping. The variations of optical properties (absorbance, diffused reflectance, and band gap) of AZO materials as compared to primitive ZnO are also identified through UV-vis studies. An attempt is made here to correlate the structural features with the photovoltaic performances of ZnO and AZO.

Sputtered of ZnO:Al thin Films for Application in Photovoltaic Solar Cells

Directory of Open Access Journals (Sweden)

Sona Flickyngerova

2008-01-01

Full Text Available High transparent and conductive, aluminium - doped zinc oxide thin films (ZnO:Al, were prepared by radio –frequency (RF diode sputtering from ZnO+2 wt. % Al2O3 target on Eutal glass substrates. Surfaces of the samples weretreated by various technological steps during preparation. The ion bombardment and the substrate temperature modified theirstructure, surface morphology, electrical and optical parameters. In this work we present changes between samples preparedat room temperature (RT and at 200°C, between samples on ion etched substrate and non-modified substrate, and effect ofion etching of the sample surface. We measured transmittance, resistivity and microroughness by AFM on all samples.

Dynamic magnetization of NiZn ferrite doped FeSiAl thin films fabricated by oblique sputtering

Energy Technology Data Exchange (ETDEWEB)

Zhong, Xiaoxi, E-mail: xiaoxi.zhong@gmail.com [Sichuan Province Key Laboratory of Information Materials and Devices Application, Chengdu University of Information Technology, Chengdu 610225 (China); Phuoc, Nguyen N. [Temasek Laboratories, National University of Singapore, 5A Engineering Drive 2, Singapore 117411 (Singapore); Soh, Wee Tee [Center for Superconducting and Magnetic Materials, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Ong, C.K. [Temasek Laboratories, National University of Singapore, 5A Engineering Drive 2, Singapore 117411 (Singapore); Center for Superconducting and Magnetic Materials, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Li, Lezhong [Sichuan Province Key Laboratory of Information Materials and Devices Application, Chengdu University of Information Technology, Chengdu 610225 (China)

2017-06-15

Highlights: • We prepared NiZn ferrite doped FeSiAl-based thin films using oblique deposition technique. • The magnetic properties of FeSiAl-based thin films were systematically studied. • Two ferromagnetic resonance peaks were observed in the permeability spectra. • The thermal stability of microwave properties of FeSiAl-based films was studied. • The thermal stability of properties we studied was relatively good. - Abstract: In this study, we comprehensively investigate the dynamic magnetic properties of FeSiAl-NiZnFeO thin films prepared by the oblique deposition method via a shorted microstrip perturbation technique. For the films with higher oblique angle and NiZn ferrite doping amount, there are two ferromagnetic resonance peaks observed in the permeability spectra, and both of the two peaks originate from FeSiAl. Furthermore, the magnetic anisotropy field H{sub K} of the ferromagnetic resonance peak at higher frequency is enhanced with increasing doping amount, which is interpreted in terms of the contribution of reinforced stress-induced anisotropy and shape anisotropy brought about by doping elements and oblique sputtering method. In addition, the thermal stability of the ferromagnetic resonance frequency f{sub FMR} of FeSiAl-NiZnFeO films with oblique angles of 35° and 45° with respect to temperature ranging from 300 K to 420 K is deteriorated with increasing ferrite doping amount, which is mainly ascribed to the influence of pair-ordering anisotropy and/or the reduction of the FeSiAl grain size.

Low-threshold pure UV electroluminescence from n-ZnO:Al/i-layer/n-GaN heterojunction

International Nuclear Information System (INIS)

Li Songzhan; Fang Guojia; Long Hao; Wang Haoning; Huang Huihui; Mo Xiaoming; Zhao Xingzhong

2012-01-01

Ultraviolet (UV) electroluminescence (EL) of n-ZnO:Al (AZO)/i-layer/n-GaN heterojunctions with different intrinsic layers has been obtained. Rectifying behavior and EL spectra of the heterojunctions are investigated at room temperature. Under positive voltage, a dominant UV emission peak around ∼370 nm is observed for both AZO/i-ZnO/n-GaN and AZO/i-MgO/n-GaN heterojunctions. Nevertheless, the UV emission peak intensity of AZO/i-MgO/n-GaN heterojunction is much stronger than that of AZO/i-ZnO/n-GaN heterojunction at the same voltage. The threshold voltage of AZO/i-MgO/n-GaN heterostructured device is as low as 2.3 V. The difference of EL spectra and the emission mechanism in these devices are discussed. - Highlights: ► UV electroluminescence of n-ZnO:Al/i-layer/n-GaN heterojunctions has been obtained. ► Under positive voltage, a dominant UV emission peak around ∼370 nm is observed for both heterojunctions. ► The UV emission peak intensity of the heterojunction with i-MgO layer is much stronger than that with i-ZnO layer at the same voltage. ► The threshold voltage of n-ZnO:Al/i-MgO/n-GaN heterostructured device is as low as 2.3 V.

Studies on morphology, electrical and optical characteristics of Al-doped ZnO thin films grown by atomic layer deposition

Science.gov (United States)

Chen, Li; Chen, Xinliang; Zhou, Zhongxin; Guo, Sheng; Zhao, Ying; Zhang, Xiaodan

2018-03-01

Al doped ZnO (AZO) films deposited on glass substrates through the atomic layer deposition (ALD) technique are investigated with various temperatures from 100 to 250 °C and different Zn : Al cycle ratios from 20 : 0 to 20 : 3. Surface morphology, structure, optical and electrical properties of obtained AZO films are studied in detail. The Al composition of the AZO films is varied by controlling the ratio of Zn : Al. We achieve an excellent AZO thin film with a resistivity of 2.14 × 10‑3 Ω·cm and high optical transmittance deposited at 150 °C with 20 : 2 Zn : Al cycle ratio. This kind of AZO thin films exhibit great potential for optoelectronics device application. Project supported by the State Key Development Program for Basic Research of China (Nos. 2011CBA00706, 2011CBA00707) and the Tianjin Applied Basic Research Project and Cutting-Edge Technology Research Plan (No. 13JCZDJC26900).

Characterization of corrosion products of Zn and Zn–Mg–Al coated steel in a marine atmosphere

International Nuclear Information System (INIS)

Diler, E.; Rouvellou, B.; Rioual, S.; Lescop, B.; Nguyen Vien, G.; Thierry, D.

2014-01-01

Highlights: • The corrosion behaviour of Zn–Mg–Al alloy in marine environment is characterized. • Zn–Mg–Al alloy shows a better corrosion resistance than Zn. • Strong enhancement of NaZn 4 Cl(OH) 6 SO 4 ·6H 2 O in the corrosion products is observed. • Al 3+ and Mg 2+ induced quenching effects in corrosion activity are described. - Abstract: The corrosion behaviour of pure zinc and zinc–magnesium–aluminium alloy (ZMA) has been studied during 6 months of exposure in marine environment (Brest, France). The composition of corrosion products is analysed using infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). An improved corrosion resistance of ZMA is observed. This improvement is found to be connected to Mg 2+ and Al 3+ induced quenching of corrosion activity and to the enhancement of NaZn 4 Cl(OH) 6 SO 4 ·6H 2 O in the formed corrosion product

Effect Of Compaction Pressure And Sintering Temperature On The Liquid Phase Sintering Behavior Of Al-Cu-Zn Alloy

Directory of Open Access Journals (Sweden)

Lee S.H.

2015-06-01

Full Text Available The liquid phase sintering characteristics of Al-Cu-Zn alloy were investigated with respect to various powder metallurgy processing conditions. Powders of each alloying elements were blended to form Al-6Cu-5Zn composition and compacted with pressures of 200, 400, and 600 MPa. The sintering process was performed at various temperatures of 410, 560, and 615°C in N2 gas atmosphere. Density and micro-Vickers hardness measurements were conducted at different processing stages, and transverse rupture strength of sintered materials was examined for each condition, respectively. The microstructure was characterized using optical microscope and scanning electron microscopy. The effect of Zn addition on the liquid phase sintering behavior during P/M process of the Al-Cu-Zn alloy was also discussed in detail.

Impact of thickness reduction of the ZnO:Al window layer on opto-electronical properties of CIGSSe solar cells

Energy Technology Data Exchange (ETDEWEB)

Keller, Jan; Knipper, M.; Parisi, J.; Riedel, I. [Thin Film Photovoltaics, University of Oldenburg, D-26111 Oldenburg (Germany); Dalibor, T.; Avellan, A. [AVANCIS GmbH and Co. KG, D-81739 Munich (Germany)

2011-07-01

The application of highly doped transparent conducting oxides in chalcopyrite solar cells requires an optimized trade-off between optical transmission and sheet-conductivity. In this respect we studied the thickness variation of ZnO:Al films used as window layer in Cu(In,Ga)(Se,S){sub 2} (CIGSSe) thin film solar cells. Thin ZnO:Al layers (200nm) on glass exhibit significantly enhanced transmission at wavelengths {lambda}<400nm while a considerable sub-bandgap absorption at {lambda}>800nm appears in thicker films which is attributed to free charge carrier absorption. The IV-characteristics of CIGSSe solar cells with d{sub ZnO:Al}=200nm exhibit a strong enhancement of the short-circuit current density J{sub SC} ({delta}J{sub SC}=3mA) as compared to samples with conventional ZnO:Al-film thickness. However, the reduced parallel (R{sub p}) and increased series (R{sub s}) resistance of samples with thin ZnO:Al-layer cause reduction of the fill factor, which has direct consequences for the series connection of cells in a CIGSSe-module. XRD-diffractograms suggest that the high R{sub s} in thin ZnO:Al is not only related to the thickness but also due to reduced (002)-texture that appears to be beneficial for lateral conductivity. By thermographic investigations we are able to directly locate the cell-regimes responsible for the decreased R{sub p}.

Aluminum anode for aluminum-air battery - Part II: Influence of In addition on the electrochemical characteristics of Al-Zn alloy in alkaline solution

Science.gov (United States)

Park, In-Jun; Choi, Seok-Ryul; Kim, Jung-Gu

2017-07-01

Effects of Zn and In additions on the aluminum anode for Al-air battery in alkaline solution are examined by the self-corrosion rate, cell voltage, current-voltage characteristics, anodic polarization, discharge performance and AC impedance measurements. The passivation behavior of Zn-added anode during anodic polarization decreases the discharge performance of Al-air battery. The addition of In to Al-Zn anode reduces the formation of Zn passivation film by repeated adsorption and desorption behavior of In ion onto anode surface. The attenuated Zn passive layer by In ion attack leads to the improvement of discharge performance of Al-air battery.

Comparative first-principles analysis of undoped and Co{sup 2+}-doped {alpha}-ZnAl{sub 2}S{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Brik, M.G., E-mail: brik@fi.tartu.ee [Institute of Physics, University of Tartu, Riia 142, Tartu 51014 (Estonia); Nazarov, M. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Institute of Applied Physics, Academiei Street 5, Chisinau MD-2028, Republic of Moldova (Moldova, Republic of); Ahmad Fauzi, M.N. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Kulyuk, L.; Anghel, S. [Institute of Applied Physics, Academiei Street 5, Chisinau MD-2028, Republic of Moldova (Moldova, Republic of); Sushkevich, K. [Moldova State University, Mateevici Street 60, Chisinau MD-2009, Republic of Moldova (Moldova, Republic of); Boulon, G. [Physical Chemistry of Luminescent Materials, Claude Bernard Lyon 1 University, UMR 5620 CNRS, La Doua, 69622 Villeurbanne (France)

2013-02-15

Highlights: Black-Right-Pointing-Pointer Structural, electronic, and optical properties of {alpha}-ZnAl{sub 2}S{sub 4}:Co{sup 2+} were calculated. Black-Right-Pointing-Pointer Ab initio and crystal field methods were used in all calculations. Black-Right-Pointing-Pointer Position of the Co{sup 2+} energy levels in the host band gap was estimated. - Abstract: The experimental and theoretical studies of the optical properties of pure {alpha}-ZnAl{sub 2}S{sub 4} and {alpha}-ZnAl{sub 2}S{sub 4}:Co{sup 2+} crystals were carried out. The ab initio and crystal field calculations of the structural and optical properties of {alpha}-ZnAl{sub 2}S{sub 4}:Co{sup 2+} were compared with the corresponding experimental data. It was shown that the lowest cobalt 3d states are located at about 0.5 eV above the valence band's top. The complete energy level scheme of the {alpha}-ZnAl{sub 2}S{sub 4}:Co{sup 2+} system, which includes the host's electronic band structure and impurity ion's energy levels, was suggested on the basis of the performed calculations.

SrZnO nanostructures grown on templated Al2O3 substrates by pulsed laser deposition

Science.gov (United States)

Labis, Joselito P.; Alanazi, Anwar Q.; Albrithen, Hamad A.; El-Toni, Ahmed Mohamed; Hezam, Mahmoud; Elafifi, Hussein Elsayed; Abaza, Osama M.

2017-09-01

The parameters of pulsed laser deposition (PLD) have been optimized to design different nanostructures of Strontium-alloyed zinc oxide (SrZnO). In this work, SrZnO nanostructures are grown on Al2O3 substrates via two-step templating/seeding approach. In the temperature range between 300 - 750 oC and O2 background pressures between 0.01 and 10 Torr, the growth conditions have been tailored to grow unique pointed leaf-like- and pitted olive-like nanostructures. Prior to the growth of the nanostructures, a thin SrZnO layer that serves as seed layer/template is first deposited on the Al2O3 substrates at ˜300oC and background oxygen pressure of 10 mTorr. The optical properties of the nanostructures were examined by UV/Vis spectroscopy and photoluminescence (PL), while the structures/morphologies were examined by SEM, TEM, and XRD. The alloyed SrZnO nanostructures, grown by ablating ZnO targets with 5, 10, 25% SrO contents, have in common a single-crystal hexagonal nanostructure with (0002) preferential orientation and have shown remarkable changes in the morphological and optical properties of the materials. To date, this is the only reported work on optimization of laser ablation parameters to design novel SrZnO nanostructures in the 5-25% alloying range, as most related Sr-doped ZnO studies were done below 7% doping. Although the physical properties of ZnO are modified via Sr doping, the mechanism remains unclear. The PLD-grown SrZnO nanostructures were directly grown onto the Al2O3 substrates; thus making these nanomaterials very promising for potential applications in biosensors, love-wave filters, solar cells, and ultrasonic oscillators.

SrZnO nanostructures grown on templated Al2O3 substrates by pulsed laser deposition

Directory of Open Access Journals (Sweden)

Joselito P. Labis

2017-09-01

Full Text Available The parameters of pulsed laser deposition (PLD have been optimized to design different nanostructures of Strontium-alloyed zinc oxide (SrZnO. In this work, SrZnO nanostructures are grown on Al2O3 substrates via two-step templating/seeding approach. In the temperature range between 300 - 750 oC and O2 background pressures between 0.01 and 10 Torr, the growth conditions have been tailored to grow unique pointed leaf-like- and pitted olive-like nanostructures. Prior to the growth of the nanostructures, a thin SrZnO layer that serves as seed layer/template is first deposited on the Al2O3 substrates at ∼300oC and background oxygen pressure of 10 mTorr. The optical properties of the nanostructures were examined by UV/Vis spectroscopy and photoluminescence (PL, while the structures/morphologies were examined by SEM, TEM, and XRD. The alloyed SrZnO nanostructures, grown by ablating ZnO targets with 5, 10, 25% SrO contents, have in common a single-crystal hexagonal nanostructure with (0002 preferential orientation and have shown remarkable changes in the morphological and optical properties of the materials. To date, this is the only reported work on optimization of laser ablation parameters to design novel SrZnO nanostructures in the 5-25% alloying range, as most related Sr-doped ZnO studies were done below 7% doping. Although the physical properties of ZnO are modified via Sr doping, the mechanism remains unclear. The PLD-grown SrZnO nanostructures were directly grown onto the Al2O3 substrates; thus making these nanomaterials very promising for potential applications in biosensors, love-wave filters, solar cells, and ultrasonic oscillators.

Enhanced photoluminescence and Raman properties of Al-Doped ZnO nanostructures prepared using thermal chemical vapor deposition of methanol assisted with heated brass.

Directory of Open Access Journals (Sweden)

Tamil Many K Thandavan

Full Text Available Vapor phase transport (VPT assisted by mixture of methanol and acetone via thermal evaporation of brass (CuZn was used to prepare un-doped and Al-doped zinc oxide (ZnO nanostructures (NSs. The structure and morphology were characterized by field emission scanning electron microscopy (FESEM and x-ray diffraction (XRD. Photoluminescence (PL properties of un-doped and Al-doped ZnO showed significant changes in the optical properties providing evidence for several types of defects such as zinc interstitials (Zni, oxygen interstitials (Oi, zinc vacancy (Vzn, singly charged zinc vacancy (VZn-, oxygen vacancy (Vo, singly charged oxygen vacancy (Vo+ and oxygen anti-site defects (OZn in the grown NSs. The Al-doped ZnO NSs have exhibited shifted PL peaks at near band edge (NBE and red luminescence compared to the un-doped ZnO. The Raman scattering results provided evidence of Al doping into the ZnO NSs due to peak shift from 145 cm-1 to an anomalous peak at 138 cm-1. Presence of enhanced Raman signal at around 274 and 743 cm-1 further confirmed Al in ZnO NSs. The enhanced D and G band in all Al-doped ZnO NSs shows possible functionalization and doping process in ZnO NSs.

Enhanced photoluminescence and Raman properties of Al-Doped ZnO nanostructures prepared using thermal chemical vapor deposition of methanol assisted with heated brass.

Science.gov (United States)

Thandavan, Tamil Many K; Gani, Siti Meriam Abdul; San Wong, Chiow; Md Nor, Roslan

2015-01-01

Vapor phase transport (VPT) assisted by mixture of methanol and acetone via thermal evaporation of brass (CuZn) was used to prepare un-doped and Al-doped zinc oxide (ZnO) nanostructures (NSs). The structure and morphology were characterized by field emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). Photoluminescence (PL) properties of un-doped and Al-doped ZnO showed significant changes in the optical properties providing evidence for several types of defects such as zinc interstitials (Zni), oxygen interstitials (Oi), zinc vacancy (Vzn), singly charged zinc vacancy (VZn-), oxygen vacancy (Vo), singly charged oxygen vacancy (Vo+) and oxygen anti-site defects (OZn) in the grown NSs. The Al-doped ZnO NSs have exhibited shifted PL peaks at near band edge (NBE) and red luminescence compared to the un-doped ZnO. The Raman scattering results provided evidence of Al doping into the ZnO NSs due to peak shift from 145 cm-1 to an anomalous peak at 138 cm-1. Presence of enhanced Raman signal at around 274 and 743 cm-1 further confirmed Al in ZnO NSs. The enhanced D and G band in all Al-doped ZnO NSs shows possible functionalization and doping process in ZnO NSs.

Reference Data for the Density, Viscosity, and Surface Tension of Liquid Al-Zn, Ag-Sn, Bi-Sn, Cu-Sn, and Sn-Zn Eutectic Alloys

Science.gov (United States)

Dobosz, Alexandra; Gancarz, Tomasz

2018-03-01

The data for the physicochemical properties viscosity, density, and surface tension obtained by different experimental techniques have been analyzed for liquid Al-Zn, Ag-Sn, Bi-Sn, Cu-Sn, and Sn-Zn eutectic alloys. All experimental data sets have been categorized and described by the year of publication, the technique used to obtain the data, the purity of the samples and their compositions, the quoted uncertainty, the number of data in the data set, the form of data, and the temperature range. The proposed standard deviations of liquid eutectic Al-Zn, Ag-Sn, Bi-Sn, Cu-Sn, and Sn-Zn alloys are 0.8%, 0.1%, 0.5%, 0.2%, and 0.1% for the density, 8.7%, 4.1%, 3.6%, 5.1%, and 4.0% for viscosity, and 1.0%, 0.5%, 0.3%, N/A, and 0.4% for surface tension, respectively, at a confidence level of 95%.

Thermomechanical cycling and two-way memory effect induced in Cu-Zn-Al

International Nuclear Information System (INIS)

Pons, J.

1999-01-01

The two-way shape memory effect (TWME) has been induced by thermomechanical cycling in Cu-Zn-Al alloys using a dedicated hydraulic mechanical testing soft machine with complete computer control of force, elongation and temperature. The results concerning single crystals (composition Cu-16.9 wt.% Zn-7.7 wt.% Al, nominal M s of 273 K) and polycrystals (Cu-15.8 wt.% Zn-8.3 wt.% Al, nominal M s of 230 K, mean grain size of 1 mm) are reported for two training protocols (sequence of one thermomechanical cycle of education followed by one stress free thermal cycle to check the TWME or twenty consecutive thermomechanical cycles followed by one or two checking thermal cycles). The capacity of the trained specimen for producing work under an antagonist compressive stress is also studied and the behaviour of the deformation of the specimen under such a condition at different temperatures is analysed in terms of a competition between the contributions of the different variants: trained variants with an intrinsic deformation in the direction of the tensile stress of the training process, trained variants with an intrinsic deformation which is not well orientated with respect to this direction (in the polycrystal) and new variants with an intrinsic deformation in the direction of the compressive stress which can replace the educated variants. (orig.)

Structure and electromagnetic properties of NiZn spinel ferrite with nano-sized ZnAl{sub 2}O{sub 4} additions

Energy Technology Data Exchange (ETDEWEB)

Zheng, Zongliang, E-mail: zzlma@163.com; Zhang, Huaiwu; Yang, Qinghui; Jia, Lijun

2015-11-05

In this study, nanocrystalline ZnAl{sub 2}O{sub 4} (ZA) (x = 0–20 wt%) were introduced into Ni{sub 0.4}Zn{sub 0.6}Fe{sub 2}O{sub 4} ferrite (NZ) by a solid-state reaction method combining a sol–gel auto-combustion method. The effects of ZA addition on the crystalline phase formation, microstructures, magnetic and dielectric properties were systematically investigated. X-ray diffraction and scanning electron microscope results reveal that the added ZA can fully solve into the NZ to form a ceramic with single-phase cubic spinel structure, and the grain size decreases obviously as x > 5 wt%. Meanwhile, the magnetic and dielectric properties exhibit significantly dependent on the ZA addition content. With the increasing addition level of ZA from 0 to 20 wt%, the initial permeability μ{sub i} is found increased initially and then decreased with the maximum 679 at x = 0.5 wt%. For the samples with x ≤ 5 wt%, permittivity ε′ is relatively higher at low frequencies (ε′ = 91–138 at 1 MHz) and dielectric loss tan δ{sub ε} shows distinct peak behavior. When x reaches 10 wt%, however, the ε′ and tan δ{sub ε} show very stable spectra from 1 MHz to 1 GHz. - Highlights: • Various amount of nanocrystalline ZnAl{sub 2}O{sub 4} (ZA) were introduced into NiZn ferrite. • NiZn ferrite can form single-phase spinel ceramic materials with ZA additives. • ZA has significant effects on magnetic and dielectric properties of the ceramics. • It provides a new method for fabricating NiZn ferrite with tunable properties.

Comparative first-principle analysis of un-doped and V{sup 3+}-doped {alpha}-ZnAl{sub 2}S{sub 4} spinel

Energy Technology Data Exchange (ETDEWEB)

Brik, M.G. [Institute of Physics, University of Tartu, Riia 142, Tartu 51014 (Estonia); Nazarov, M., E-mail: mvnazarov@mail.ru [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Institute of Applied Physics, Academiei Street 5, Chisinau MD-2028, Republic of Moldova (Moldova, Republic of); Ahmad-Fauzi, M.N. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Kulyuk, L.; Anghel, S. [Institute of Applied Physics, Academiei Street 5, Chisinau MD-2028, Republic of Moldova (Moldova, Republic of); Sushkevich, K. [Moldova State University, Mateevici Street 60, Chisinau, MD-2009, Republic of Moldova (Moldova, Republic of); Boulon, G. [Physical Chemistry of Luminescent Materials, Claude Bernard Lyon 1 University, UMR 5620 CNRS, La Doua, 69622 Villeurbanne (France)

2012-09-15

The experimental and theoretical studies of the optical properties of pure {alpha}-ZnAl{sub 2}S{sub 4} and {alpha}-ZnAl{sub 2}S{sub 4}:V{sup 3+} crystals were carried out. The ab initio and crystal field calculations of the structural and optical properties of {alpha}-ZnAl{sub 2}S{sub 4}:V{sup 3+} were compared with the corresponding experimental data. It was shown that the lowest vanadium 3d states are located at about 1.36 eV above the valence band's top. The complete energy level scheme of the {alpha}-ZnAl{sub 2}S{sub 4}:V{sup 3+} system, which includes the host's electronic band structure and impurity ion's energy levels, was suggested on the basis of the performed calculations. - Highlights: Black-Right-Pointing-Pointer Experimental and theoretical studies of {alpha}-ZnAl{sub 2}S{sub 4} and {alpha}-ZnAl{sub 2}S{sub 4}:V{sup 3+} crystals were carried out. Black-Right-Pointing-Pointer Ab inito and crystal field calculations were used in structural and spectroscopic analyses. Black-Right-Pointing-Pointer The complete energy level scheme of the {alpha}-ZnAl{sub 2}S{sub 4}:V{sup 3+} system was suggested. Black-Right-Pointing-Pointer The lowest vanadium 3d states are located at about 1.36 eV above the valence band's top.

ZnO:Al thin films deposited by RF-magnetron sputtering with tunable and uniform properties.

Science.gov (United States)

Miorin, E; Montagner, F; Battiston, S; Fiameni, S; Fabrizio, M

2011-03-01

Nanostructured, high quality and large area Al-doped ZnO (ZnO:Al) thin films were obtained by radiofrequency (RF) magnetron sputtering. The sample rotation during deposition has resulted in excellent spatial distribution of thickness and electro-optical properties compared to that obtained under static conditions. ZnO:Al thin films are employed in a large number of devices, including thin film solar cells, where the uniformity of the properties is a key factor for a possible up-scaling of the research results to industrially relevant substrate sizes. A chemical post etching treatment was employed achieving tunable surface nanotextures to generate light scattering at the desired wavelength for improved cell efficiency. Since the film resistivity is only slightly increased by the etching, this post-deposition step allows separating the optimization of electro-optical properties from light scattering behavior. The thin films were characterized by FE-SEM, XRD, UV-VIS spectroscopy, four probe and van der Paw techniques.

X-ray photoelectron spectroscopy study and thermoelectric properties of Al-doped ZnO thin films

International Nuclear Information System (INIS)

Li Li; Fang Liang; Zhou Xianju; Liu Ziyi; Zhao Liang; Jiang Sha

2009-01-01

In this paper, high quality Al-doped ZnO (AZO) thin films were prepared by direct current (DC) reactive magnetron sputtering using a Zn target (99.99%) containing Al of 1.5 wt.%. The films obtained were characterized by X-ray photoelectron spectroscopy (XPS) and thermoelectric measurements. The XPS results reveal that Zn and Al exist only in oxidized state, while there are dominant crystal lattice and rare adsorbed oxygen for O in the annealed AZO thin films. The studies of thermoelectric property show a striking thermoelectric effect in the AZO thin films. On the one hand, the thermoelectromotive and magnetothermoelectromotive forces increase linearly with increasing temperature difference (ΔT). On the other hand, the thermoelectric power (TEP) decreases with the electrical resistance of the sample. But the TEP increases with the increase of temperature below 300 K, and it nearly does not change around room temperature. The experimental results also demonstrate that the annealing treatment increases TEP, while the external magnetic field degrades TEP.

High deposition rate of low resistive and transparent ZnO:Al on glass with an industrial moving belt APCVD reactor

NARCIS (Netherlands)

Illiberi, A.; Kniknie, B.; Steijvers, H.L.A.H.; Habets, D.; Simons, P.J.P.M.; Beckers, E.H.A.; Deelen, J. van

2012-01-01

Aluminum doped ZnOx (ZnOx:Al) films have been deposited on glass in an in-line industrial-type reactor by a metalorganic chemical vapor deposition process at atmospheric pressure. ZnOx:Al films can be grown at very high deposition rates of ~ 14 nm/s for a substrate speed from 150 mm/min to 500

Properties of ZnO:Al Films Prepared by Spin Coating of Aged Precursor Solution

International Nuclear Information System (INIS)

Shrestha, Shankar Prasad; Ghimire, Rishi; Nakarmi, Jeevan Jyoti; Kim, Young Sung; Shrestha, Sabita; Park, Chong Yun; Boo, Jin Hyo

2010-01-01

Transparent conducting undoped and Al impurity doped ZnO films were deposited on glass substrate by spin coat technique using 24 days aged ZnO precursor solution with solution of ethanol and diethanolamine. The films were characterized by UV-Visible spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), electrical resistivity (ρ), carrier concentration (n), and hall mobility (μ) measurements. XRD data show that the deposited film shows polycrystalline nature with hexagonal wurtzite structure with preferential orientation along (002) crystal plane. The SEM images show that surface morphology, porosity and grain sizes are affected by doping concentration. The Al doped samples show high transmittance and better resistivity. With increasing Al concentration only mild change in optical band gap is observed. Optical properties are not affected by aging of parent solution. A lowest resistivity (8.5 x 10 -2 ohm cm) is observed at 2 atomic percent (at.%) Al. With further increase in Al concentration, the resistivity started to increase significantly. The decrease resistivity with increasing Al concentration can be attributed to increase in both carrier concentration and hall mobility

Kinetics of cellular transformation and competing precipitation mechanisms during sub-eutectoid annealing of U10Mo alloys

Energy Technology Data Exchange (ETDEWEB)

Jana, Saumyadeep; Devaraj, Arun; Kovarik, Libor; Arey, Bruce W.; Sweet, Lucas E.; Varga, Tamas; Lavender, Curt A.; Joshi, Vineet V.

2017-11-01

Transformation kinetics of metastable body-centered cubic γ-UMo phase in U-10 wt.percent Mo alloy during annealing at sub-eutectoid temperatures of 500C and 400C has been determined as a function of time using detailed microstructural characterization by scanning electron microscopy, X-ray diffraction analysis, scanning transmission electron microscopy, and atom probe tomography. Based on the results, we found that the phase transformation is initiated by cellular transformation at both the temperatures, which results in formation of a lamellar microstructure along prior γ-UMo grain boundaries.

Low resistivity of Ni–Al co-doped ZnO thin films deposited by DC magnetron sputtering at low sputtering power

Energy Technology Data Exchange (ETDEWEB)

Lee, JongWoo [Department of Materials Science and Engineering, Pusan National University, San 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Hui, K.N. [Department of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Hui, K.S., E-mail: kshui@hanyang.ac.kr [Department of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Cho, Y.R., E-mail: yescho@pusan.ac.kr [Department of Materials Science and Engineering, Pusan National University, San 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Chun, Ho-Hwan [Global Core Research Center for Ships and Offshore Plants (GCRC-SOP), Pusan National University, San 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of)

2014-02-28

Ni–Al co-doped ZnO (NiAl:ZnO) thin films were deposited on glass substrates by DC magnetron sputtering in Ar using a single ceramic, spark-plasma-sintered target with 2 wt% Al and 5 wt% Ni. The effects of the sputtering power and gas pressure on the NiAl:ZnO films were studied. The structural, electrical, and optical properties of the films were characterized by X-ray diffraction, field emission scanning electron microscopy, Hall effect measurements and UV–vis transmission spectroscopy. As the sputtering power and gas pressure increased, the crystallinity, electrical properties and optical band gap of the films were improved. The NiAl:ZnO film deposited at 40 W at 6.0 mTorr had the strongest (0 0 2) XRD peak and the lowest resistivity of approximately 2.19 × 10{sup −3} Ω cm with an optical transmittance of 90%.

Treatment of textile effluents by chloride-intercalated Zn-, Mg- and Ni-Al layered double hydroxides

Directory of Open Access Journals (Sweden)

F. Z. Mahjoubi

2017-09-01

Full Text Available This work involved the preparation, characterization and dyes removal ability of Zn-Al, Mg-Al and Ni-Al layered double hydroxide (LDH minerals intercalated by chloride ions. The materials were synthetized by the co-precipitation method. X-ray diffraction, Fourier transform infrared, thermogravimetric-differential thermal analysis and transmission electron microscopy characterization exhibited a typical hydrotalcite structure for all the samples. Adsorption experiments for methyl orange were performed in terms of solution pH, contact time and initial dye concentration. Experimental results indicate that the capacity of dye uptake augmented rapidly within the first 60 min and then stayed practically the same regardless of the concentration. Maximum adsorption occurred with acidic pH medium. Kinetic data were studied using pseudo-first-order and pseudo-second-order kinetic models. Suitable correlation was acquired with the pseudo-second-order kinetic model. Equilibrium data were fitted to Langmuir and Freundlich isotherm models. The maximum Langmuir monolayer adsorption capacities were 2,758, 1,622 and 800 mg/g, respectively, for Zn-Al-Cl, Mg-Al-Cl and Ni-Al-Cl. The materials were later examined for the elimination of color and chemical oxygen demand (COD from a real textile effluent wastewater. The results indicated that the suitable conditions for color and COD removal were acquired at pH of 5. The maximum COD removal efficiency from the effluent was noted as 92.84% for Zn-Al-Cl LDH.

Investigation on the Cathodic Protection Effect of Low Pressure Cold Sprayed AlZn Coating in Seawater via Numerical Simulation

Directory of Open Access Journals (Sweden)

Guosheng Huang

2017-07-01

Full Text Available Cold spray can deposit a composite coating simply by spraying mechanically-mixed Al and Zn powders, while no quantitative data has been reported on the anti-corrosion performance of different composite cold-sprayed coatings. In the present work, the finite element method was used to estimate the cathodic protection effect by simulating the potential distribution on a damaged cold-sprayed AlZn coating on Q235 steel. The results indicate that AlZn coating can only provide a limiting cathodic protection for substrate, because it can only polarize a very narrow zone negative to −0.78 V (vs. SCE, saturated calomel electrode. The remaining area of the steel substrate still has a very high residual corrosion rate. Computational methods can be used to predict the corrosion rate of AlZn coating, and the simulation results were validated by the results of a weight loss experiment.

Stress corrosion cracking and hydrogen embrittlement of an Al-Zn-Mg-Cu alloy

International Nuclear Information System (INIS)

Song, R.G.; Dietzel, W.; Zhang, B.J.; Liu, W.J.; Tseng, M.K.; Atrens, A.

2004-01-01

The age hardening, stress corrosion cracking (SCC) and hydrogen embrittlement (HE) of an Al-Zn-Mg-Cu 7175 alloy were investigated experimentally. There were two peak-aged states during ageing. For ageing at 413 K, the strength of the second peak-aged state was slightly higher than that of the first one, whereas the SCC susceptibility was lower, indicating that it is possible to heat treat 7175 to high strength and simultaneously to have high SCC resistance. The SCC susceptibility increased with increasing Mg segregation at the grain boundaries. Hydrogen embrittlement (HE) increased with increased hydrogen charging and decreased with increasing ageing time for the same hydrogen charging conditions. Computer simulations were carried out of (a) the Mg grain boundary segregation using the embedded atom method and (b) the effect of Mg and H segregation on the grain boundary strength using a quasi-chemical approach. The simulations showed that (a) Mg grain boundary segregation in Al-Zn-Mg-Cu alloys is spontaneous, (b) Mg segregation decreases the grain boundary strength, and (c) H embrittles the grain boundary more seriously than does Mg. Therefore, the SCC mechanism of Al-Zn-Mg-Cu alloys is attributed to the combination of HE and Mg segregation induced grain boundary embrittlement

The formation of tungsten doped Al_2O_3/ZnO coatings on aluminum by plasma electrolytic oxidation and their application in photocatalysis

International Nuclear Information System (INIS)

Stojadinović, Stevan; Vasilić, Rastko; Radić, Nenad; Tadić, Nenad; Stefanov, Plamen; Grbić, Boško

2016-01-01

Highlights: • Tungsten doped Al_2O_3/ZnO coatings are formed by plasma electrolytic oxidation (PEO). • Coatings are mainly composed of alpha alumina, ZnO and metallic tungsten. • Photocatalytic activity of doped Al_2O_3/ZnO coatings is higher than of undoped ones. • The increase of photoluminescence corresponds to decrease of photocatalytic activity. • Tungsten acts as a charge trap to reduce the recombination rate of electron/hole pairs. - Abstract: Tungsten doped Al_2O_3/ZnO coatings are formed by plasma electrolytic oxidation of aluminum substrate in supporting electrolyte (0.1 M boric acid + 0.05 M borax + 2 g/L ZnO) with addition of different concentrations of Na_2WO_4·2H_2O. The morphology, crystal structure, chemical composition, and light absorption characteristics of formed surface coatings are investigated. The X-ray diffraction and X-ray photoelectron spectroscopy results indicate that formed surface coatings consist of alpha and gamma phase of Al_2O_3, ZnO, metallic tungsten and WO_3. Obtained results showed that incorporated tungsten does not have any influence on the absorption spectra of Al_2O_3/ZnO coatings, which showed invariable band edge at about 385 nm. The photocatalytic activity of undoped and tungsten doped Al_2O_3/ZnO coatings is estimated by the photodegradation of methyl orange. The photocatalytic activity of tungsten doped Al_2O_3/ZnO coatings is higher thanof undoped Al_2O_3/ZnO coatings; the best photocatalytic activity is ascribed to coatings formed in supporting electrolyte with addition of 0.3 g/L Na_2WO_4·2H_2O. Tungsten in Al_2O_3/ZnO coatings acts as a charge trap, thus reducing the recombination rate of photogenerated electron-hole pairs. The results of PL measurements are in agreement with photocatalytic activity. Declining PL intensity corresponds to increasing photocatalytic activity of the coatings, indicating slower recombination of electron-hole pairs.

Structural, vibrational and morphological properties of layered double hydroxides containing Ni{sup 2+}, Zn{sup 2+}, Al{sup 3+} and Zr{sup 4+} cations

Energy Technology Data Exchange (ETDEWEB)

Bezerra, Débora M. [Instituto de Química de São Carlos, Universidade de São Paulo, CP 780, CEP 13566-590 São Carlos, SP (Brazil); Rodrigues, João E.F.S. [Instituto de Física de São Carlos, Universidade de São Paulo, CP 780, CEP 13560-970 São Carlos, SP (Brazil); Assaf, Elisabete M., E-mail: eassaf@iqsc.usp.br [Instituto de Química de São Carlos, Universidade de São Paulo, CP 780, CEP 13566-590 São Carlos, SP (Brazil)

2017-03-15

Layered double hydroxides are anionic clays with formula [M{sup II}{sub 1−x} M{sup III}{sub x}(OH){sub 2}]{sup q+}[A{sup n−}]{sub q/n}·mH{sub 2}O, finding possible uses as catalyst support, adsorbents and so on. In this paper, we address the phase formation of layered double hydroxides containing Ni{sup 2+}, Zn{sup 2+}, Al{sup 3+} and Zr{sup 4+} cations, namely, NiZn-Al, NiZn-AlZr and NiZn-Zr compositions obtained by the coprecipitation method. Such systems were characterized by X-ray diffraction, confirming the phase formation for NiZn-Al and NiZn-AlZr samples. Infrared and Raman spectroscopies elucidated the anion and water molecules occurrence in the interlayer. Nitrogen physisorption (BET method) determined the presence of pores and specific surface area. The isotherm shapes were Type IV, according to the IUPAC, and represent a mesoporous structure. A morphological study was performed by means of scanning and transmission electron microscopies, and particle size values of 120, 131 and 235 nm for NiZn-Al, NiZn-AlZr and NiZn-Zr, respectively, were determined. Thermogravimetric analysis of the decomposition of the systems revealed that their complete disintegration occurred at ~ 450 °C and resulted in mixed oxides.

Enhanced Al and Zn removal from coal-mine drainage during rapid oxidation and precipitation of Fe oxides at near-neutral pH

Science.gov (United States)

Burrows, Jill E.; Cravotta, Charles A.; Peters, Stephen C.

2017-01-01

Net-alkaline, anoxic coal-mine drainage containing ∼20 mg/L FeII and ∼0.05 mg/L Al and Zn was subjected to parallel batch experiments: control, aeration (Aer 1 12.6 mL/s; Aer 2 16.8 mL/s; Aer 3 25.0 mL/s), and hydrogen peroxide (H2O2) to test the hypothesis that aeration increases pH, FeII oxidation, hydrous FeIII oxide (HFO) formation, and trace-metal removal through adsorption and coprecipitation with HFO. During 5.5-hr field experiments, pH increased from 6.4 to 6.7, 7.1, 7.6, and 8.1 for the control, Aer 1, Aer 2, and Aer 3, respectively, but decreased to 6.3 for the H2O2 treatment. Aeration accelerated removal of dissolved CO2, Fe, Al, and Zn. In Aer 3, dissolved Al was completely removed within 1 h, but increased to ∼20% of the initial concentration after 2.5 h when pH exceeded 7.5. H2O2 promoted rapid removal of all dissolved Fe and Al, and 13% of dissolved Zn.Kinetic modeling with PHREEQC simulated effects of aeration on pH, CO2, Fe, Zn, and Al. Aeration enhanced Zn adsorption by increasing pH and HFO formation while decreasing aqueous CO2 available to form ZnCO30 and Zn(CO3)22− at high pH. Al concentrations were inconsistent with solubility control by Al minerals or Al-containing HFO, but could be simulated by adsorption on HFO at pH oxidation with pH adjustment to ∼7.5 could be effective for treating high-Fe and moderate-Zn concentrations, whereas chemical oxidation without pH adjustment may be effective for treating high-Fe and moderate-Al concentrations.

Effects of Surface Morphology ZnAl2O4 of Ceramic Materials on Osteoblastic Cells Responses

International Nuclear Information System (INIS)

Suarez-Franco, J.L.; Fernandez-Pedrero, J.A.; Ivarez-Perez, M.A.; Garcia-Hipolito, M.; Surarez-Rosales, M.; Fregoso, O.; Juarez-Islas, J.A.; Ivarez-Perez, M.A.

2013-01-01

Ceramic scaffolds are widely studied in the tissue engineering field due to their potential in medical applications as bone substitutes or as bone-filling materials. The purpose of this study was to investigate the effect of surface morphology of nano structure thin films of ZnAl 2 O 4 prepared by spray pyrolysis and bulk pellets of polycrystalline ZnAl 2 O 4 prepared by chemical coprecipitation reaction on the in vitro cell adhesion, viability, and cell-material interactions of osteoblastic cells. Our result showed that cell attachment was significantly enhanced from 60 to 80% on the ZnAl 2 O 4 nano structured material surface when compared with bulk ceramic surfaces. Moreover, our results showed that the balance of morphological properties of the thin film nano structure ceramic improves cell-material interaction with enhanced spreading and filopodia with multiple cellular extensions on the surface of the ceramic and enhancing cell viability/proliferation in comparison with bulk ceramic surfaces used as control. Altogether, these results suggest that zinc aluminate nano structured materials have a great potential to be used in dental implant and bone substitute applications.Ceramic scaffolds are widely studied in the tissue engineering field due to their potential in medical applications as bone substitutes or as bone-filling materials. The purpose of this study was to investigate the effect of surface morphology of nano structure thin films of ZnAl 2 O 4 prepared by spray pyrolysis and bulk pellets of polycrystalline ZnAl 2 O 4 prepared by chemical coprecipitation reaction on the in vitro cell adhesion, viability, and cell-material interactions of osteoblastic cells. Our result showed that cell attachment was significantly enhanced from 60 to 80% on the ZnAl 2 O 4 nano structured material surface when compared with bulk ceramic surfaces. Moreover, our results showed that the balance of morphological properties of the thin film nano structure ceramic improves

Grain Refinement of Al-Si-Fe-Cu-Zn-Mn Based Alloy by Al-Ti-B Alloy and Its Effect on Mechanical Properties.

Science.gov (United States)

Yoo, Hyo-Sang; Kim, Yong-Ho; Jung, Chang-Gi; Lee, Sang-Chan; Lee, Seong-Hee; Son, Hyeon-Taek

2018-03-01

We investigated the effects of Al-5.0wt%Ti-1.0wt%B addition on the microstructure and mechanical properties of the as-extruded Al-0.15wt%Si-0.2wt%Fe-0.3wt%Cu-0.15wt%Zn-0.9wt%Mn based alloys. The Aluminum alloy melt was held at 800 °C and then poured into a mould at 200 °C. Aluminum alloys were hot-extruded into a rod that was 12 mm in thickness with a reduction ratio of 38:1. AlTiB addition to Al-0.15Si-0.2Fe-0.3Cu-0.15Zn-0.9Mn based alloys resulted in the formation of Al3Ti and TiB2 intermetallic compounds and grain refinement. With increasing of addition AlTiB, ultimate tensile strength increased from 93.38 to 99.02 to 100.01 MPa. The tensile strength of the as-extruded alloys was improved due to the formation of intermetallic compounds and grain refinement.

Zr-based conversion layer on Zn-Al-Mg alloy coated steel sheets: insights into the formation mechanism

International Nuclear Information System (INIS)

Lostak, Thomas; Maljusch, Artjom; Klink, Björn; Krebs, Stefan; Kimpel, Matthias; Flock, Jörg; Schulz, Stephan; Schuhmann, Wolfgang

2014-01-01

Zr-based conversion layers are considered as environmentally friendly alternatives replacing trication phosphatation in the automotive industry. Based on excellent electronic barrier properties they provide an effective corrosion protection of the metallic substrate. In this work, thin protective layers were grown on novel Zn-Al-Mg alloy coated steel sheets by increasing the local pH-value at the sample surface leading to deposition of a Zr-based conversion layer. For this purpose Zn-Al-Mg alloy (ZM) coated steel sheets were treated in an aqueous model conversion solution containing well-defined amounts of hexafluorozirconic acid (H 2 ZrF 6 ) and characterized after different immersion times with SKPFM and field emission SEM (FE-SEM)/EDX techniques. A deposition mechanism of Zr-based conversion coatings on microstructural heterogeneous Zn-Al-Mg alloy surfaces was proposed

Phase-coherent electron transport in (Zn, Al)O{sub x} thin films 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; Ajimsha, R. S.; Joshi, M. P.; Kukreja, L. M. [Laser Materials Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India)

2014-11-24

A clear signature of disorder induced quantum-interference phenomena leading to phase-coherent electron transport was observed in (Zn, Al)O{sub x} thin films grown by atomic layer deposition. The degree of static-disorder was tuned by varying the Al concentration through periodic incorporation of Al{sub 2}O{sub 3} sub-monolayer in ZnO. All the films showed small negative magnetoresistance due to magnetic field suppressed weak-localization effect. The temperature dependence of phase-coherence length (l{sub φ}∝T{sup −3/4}), as extracted from the magnetoresistance measurements, indicated electron-electron scattering as the dominant dephasing mechanism. The persistence of quantum-interference at relatively higher temperatures up to 200 K is promising for the realization of ZnO based phase-coherent electron transport devices.

Probing the electrical properties of highly-doped Al:ZnO nanowire ensembles

KAUST Repository

Noriega, Rodrigo; Rivnay, Jonathan; Goris, Ludwig; Kälblein, Daniel; Klauk, Hagen; Kern, Klaus; Thompson, Linda M.; Palke, Aaron C.; Stebbins, Jonathan F.; Jokisaari, Jacob R.; Kusinski, Greg; Salleo, Alberto

2010-01-01

The analysis of transparent conducting oxide nanostructures suffers from a lack of high throughput yet quantitatively sensitive set of analytical techniques that can properly assess their electrical properties and serve both as characterization and diagnosis tools. This is addressed by applying a comprehensive set of characterization techniques to study the electrical properties of solution-grown Al-doped ZnO nanowires as a function of composition from 0 to 4 at. % Al:Zn. Carrier mobility and charge density extracted from sensitive optical absorption measurements are in agreement with those extracted from single-wire field-effect transistor devices. The mobility in undoped nanowires is 28 cm2 /V s and decreases to ∼14 cm2 /V s at the highest doping density, though the carrier density remains approximately constant (1020 cm-3) due to limited dopant activation or the creation of charge-compensating defects. Additionally, the local geometry of the Al dopant is studied by nuclear magnetic resonance, showing the occupation of a variety of dopant sites. © 2010 American Institute of Physics.

Structural reversibility of a ternary CuO–ZnO–Al2O3 ex hydrotalcite-containing material during wet Pd impregnation

NARCIS (Netherlands)

López Granados, M.; Melián-Cabrera, I.; Fierro, J.L.G.

2002-01-01

A Cu–Zn–Al precursor was synthesized by coprecipitation of the corresponding cations with sodium carbonate at constant pH and temperature. CuO–ZnO–Al2O3 composite oxide support was obtained by calcination (673 K) of the Cu–Zn–Al precursor. Two palladium-modified CuO–ZnO–Al2O3 samples were prepared

Tuning the field distribution and fabrication of an Al@ZnO core-shell nanostructure for a SPR-based fiber optic phenyl hydrazine sensor.

Science.gov (United States)

Tabassum, Rana; Kaur, Parvinder; Gupta, Banshi D

2016-05-27

We report the fabrication and characterization of a surface plasmon resonance (SPR)-based fiber optic sensor that uses coatings of silver and aluminum (Al)-zinc oxide (ZnO) core-shell nanostructure (Al@ZnO) for the detection of phenyl hydrazine (Ph-Hyd). To optimize the volume fraction (f) of Al in ZnO and the thickness of the core-shell nanostructure layer (d), the electric field intensity along the normal to the multilayer system is simulated using the two-dimensional multilayer matrix method. The Al@ZnO core-shell nanostructure is prepared using the laser ablation technique. Various probes are fabricated with different values of f and an optimized thickness of core-shell nanostructure for the characterization of the Ph-Hyd sensor. The performance of the Ph-Hyd sensor is evaluated in terms of sensitivity. It is found that the Ag/Al@ZnO nanostructure core-shell-coated SPR probe with f = 0.25 and d = 0.040 μm possesses the maximum sensitivity towards Ph-Hyd. These results are in agreement with the simulated ones obtained using electric field intensity. In addition, the performance of the proposed probe is compared with that of probes coated with (i) Al@ZnO nanocomposite, (ii) Al nanoparticles and (iii) ZnO nanoparticles. It is found that the probe coated with an Al@ZnO core-shell nanostructure shows the largest resonance wavelength shift. The detailed mechanism of the sensing (involving chemical reactions) is presented. The sensor also manifests optimum performance at pH 7.

Electronic structure of Al- and Ga-doped ZnO films studied by hard X-ray photoelectron spectroscopy

Directory of Open Access Journals (Sweden)

M. Gabás

2014-01-01

Full Text Available Al- and Ga-doped sputtered ZnO films (AZO, GZO are semiconducting and metallic, respectively, despite the same electronic valence structure of the dopants. Using hard X-ray photoelectron spectroscopy we observe that both dopants induce a band in the electronic structure near the Fermi level, accompanied by a narrowing of the Zn 3d/O 2p gap in the valence band and, in the case of GZO, a substantial shift in the Zn 3d. Ga occupies substitutional sites, whereas Al dopants are in both substitutional and interstitial sites. The latter could induce O and Zn defects, which act as acceptors explaining the semiconducting character of AZO and the lack of variation in the optical gap. By contrast, mainly substitutional doping is consistent with the metallic-like behavior of GZO.

Fatigue crack micromechanisms in a Cu-Zn-Al shape memory alloy with pseudo-elastic behavior

Directory of Open Access Journals (Sweden)

Vittorio Di Cocco

2015-10-01

Full Text Available Shape memory property characterizes the behavior of many Ti based and Cu based alloys (SMAs. In Cu-Zn-Al SMAs, the original shape recovering is due to a bcc phase that is stable at high temperature. After an appropriate cooling process, this phase (β-phase or austenitic phase transforms reversibly into a B2 structure (transition phase and, after a further cooling process or a plastic deformation, it transforms into a DO3 phase (martensitic phase. In β-Cu-Zn-Al SMAs, the martensitic transformation due to plastic deformation is not stable at room temperature: a high temperature “austenitization” process followed by a high speed cooling process allow to obtain a martensitic phase with a higher stability. In this work, a Cu-Zn-Al SMA in “as cast” conditions has been microstructurally and metallographically characterized by means of X-Ray diffraction and Light Optical Microscope (LOM observations. Fatigue crack propagation resistance and damaging micromechanisms have been investigated corresponding to three different load ratios (R=0.10, 0.50 and 0.75

Synthesis and thermal stability of the sodalite Na6Zn2[Al6Si6O24](SO4)2 and its reaction with hydrogen

DEFF Research Database (Denmark)

Heiden, Frank; Nielsen, Ulla Gro; Warner, Terence Edwin

2012-01-01

Ca2[Al6Si6O24](SO4)2. Na6Zn2[Al6Si6O24](SO4)2 was shown to be largely immiscible with nosean, Na8[Al6Si6O24]SO4 in the solid-state. Na6Zn2[Al6Si6O24](SO4)2 decomposes above 700 °C, yielding nosean, Na8[Al6Si6O24]SO4; willemite, Zn2SiO4; gahnite, ZnAl2O4; and presumably a glass phase, 2Na2O•9SiO2...

Improved Stress Corrosion Cracking Resistance and Strength of a Two-Step Aged Al-Zn-Mg-Cu Alloy Using Taguchi Method

Science.gov (United States)

Lin, Lianghua; Liu, Zhiyi; Ying, Puyou; Liu, Meng

2015-12-01

Multi-step heat treatment effectively enhances the stress corrosion cracking (SCC) resistance but usually degrades the mechanical properties of Al-Zn-Mg-Cu alloys. With the aim to enhance SCC resistance as well as strength of Al-Zn-Mg-Cu alloys, we have optimized the process parameters during two-step aging of Al-6.1Zn-2.8Mg-1.9Cu alloy by Taguchi's L9 orthogonal array. In this work, analysis of variance (ANOVA) was performed to find out the significant heat treatment parameters. The slow strain rate testing combined with scanning electron microscope and transmission electron microscope was employed to study the SCC behaviors of Al-Zn-Mg-Cu alloy. Results showed that the contour map produced by ANOVA offered a reliable reference for selection of optimum heat treatment parameters. By using this method, a desired combination of mechanical performances and SCC resistance was obtained.

Demonstration of Al:ZnO as a plasmonic component for near-infrared metamaterials

DEFF Research Database (Denmark)

Naik, Gururaj V.; Liu, Jingjing; Kildishev, Alexander V.

2012-01-01

Noble metals such as gold and silver are conventionally used as the primary plasmonic building blocks of optical metamaterials. Making subwavelength-scale structural elements from these metals not only seriously limits the optical performance of a device due to high absorption, it also substantia....... In this letter, we replace a metal with aluminum-doped zinc oxide as a new plasmonic material and experimentally demonstrate negative refraction in an Al:ZnO/ZnO metamaterial in the near-infrared range....

Anodic behavior of Al-Zn-In sacrificial anodes at different concentration of zinc and indium

Energy Technology Data Exchange (ETDEWEB)

Keyvani, Ahmad [Shahrekord Univ. (Iran, Islamic Republic of). Dept. of Materials Engineering; Tehran Univ. (Iran, Islamic Republic of). School of Metallurgy and Materials; Saremi, Mohsen [Tehran Univ. (Iran, Islamic Republic of). School of Metallurgy and Materials; Saeri, Mohammad Reza [Shahrekord Univ. (Iran, Islamic Republic of). Dept. of Materials Engineering

2012-12-15

Al-Zn-In anodes show better performance due to the beneficial effects of Zn and In on prevention of aluminum passivity and producing a homogeneous structure for uniform corrosion of the anodes. However, there are different views about the optimum concentration of each element in the anode. In this study, the anodic behavior of Al-Zn-In alloy with different concentrations of zinc from 1 to 6wt.% and indium from 0.01 to 0.05wt.% are studied. The NACE efficiency test and polarization are used in 3wt.% NaCl solution for corrosion characterization. The results showed that zinc and indium change the anode potential to more active potentials and improve the microstructure uniformity of anodes. The latter leads to more uniform corrosion. Optimum concentrations of zinc (5wt.%) and indium (0.02wt.%) were found in this respect. (orig.)

Toxicity of nanoparticulate and bulk ZnO, Al2O3 and TiO2 to the nematode Caenorhabditis elegans

International Nuclear Information System (INIS)

Wang Huanhua; Wick, Robert L.; Xing Baoshan

2009-01-01

Limited information is available on the environmental behavior and associated potential risk of manufactured oxide nanoparticles (NPs). In this research, toxicity of nanoparticulate and bulk ZnO, Al 2 O 3 and TiO 2 were examined to the nematode Caenorhabditis elegans with Escherichia coli as a food source. Parallel experiments with dissolved metal ions from NPs were also conducted. The 24-h median lethal concentration (LC 50 ) and sublethal endpoints were assessed. Both NPs and their bulk counterparts were toxic, inhibiting growth and especially the reproductive capability of the nematode. The 24-h LC 50 for ZnO NPs (2.3 mg L -1 ) and bulk ZnO was not significantly different, but significantly different between Al 2 O 3 NPs (82 mg L -1 ) and bulk Al 2 O 3 (153 mg L -1 ), and between TiO 2 NPs (80 mg L -1 ) and bulk TiO 2 (136 mg L -1 ). Oxide solubility influenced the toxicity of ZnO and Al 2 O 3 NPs, but nanoparticle-dependent toxicity was indeed observed for the investigated NPs. - ZnO, Al 2 O 3 and TiO 2 nanoparticles are more toxic than their bulk counterparts to the nematode, Caenorhabditis elegans

Structure and Properties of Al and Ga- Doped ZnO

Science.gov (United States)

Temizer, Namik Kemal

Recently there is tremendous interest in Transparent conducting oxide (TCO) research due to the unlimited and exciting application areas. Current research is mostly focused on finding alternative low cost and sustainable materials in order to replace indium tin oxide (ITO), which caused serious concern due to the increasing cost of indium and chemical stability issues of ITO. The primary aim of this research is to develop alternative TCO materials with superior properties in order to increase the efficiency in optoelectronic applications, as well as to study the properties of these materials to fully characterize them. We have grown Al and Ga-doped ZnO films with an optimized composition under different deposition conditions in order to understand the effect of processing parameters on the film properties. We report a detailed investigation on the structure-property correlations in Ga and Al codoped ZnO films on c-sapphire substrates where the thin film microstructure varies from nanocrystalline to single crystal. We have achieved highly epitaxial films with very high optical transmittance (close to 90%) and low resistivity (˜110muO-cm) values. The films grown in an ambient oxygen partial pressure (PO2 ) of 50 mTorr and at growth temperatures from room temperature to 600°C showed semiconducting behavior, whereas samples grown at a Po2 of 1 mTorr showed metallic nature. The most striking feature is the occurrence of resistivity minima at relatively high temperatures around 110 K in films deposited at high temperatures. The structure-property correlations reveal that point defects play an important role in modifying the structural, optical, electrical and magnetic properties and such changes in physical properties are controlled predominantly by the defect content. To gain a better understanding of the conduction processes in doped ZnO thin films, we have studied the temperature variation of resistivity of some selected samples that showed some interesting behavior

Corrosion behaviors of Zn/Al-Mn alloy composite coatings deposited on magnesium alloy AZ31B (Mg-Al-Zn)

International Nuclear Information System (INIS)

Zhang Jifu; Zhang Wei; Yan Chuanwei; Du Keqin; Wang Fuhui

2009-01-01

After being pre-plated a zinc layer, an amorphous Al-Mn alloy coating was applied onto the surface of AZ31B magnesium alloy with a bath of molten salts. Then the corrosion performance of the coated magnesium alloy was examined in 3.5% NaCl solution by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the single Zn layer was active in the test solution with a high corrosion rate while the Al-Mn alloy coating could effectively protect AZ31B magnesium alloy from corrosion in the solution. The high corrosion resistance of Al-Mn alloy coating was ascribed to an intact and stable passive film formed on the coating. The performances of the passive film on Al-Mn alloy were further investigated by Mott-Schottky curve and X-ray photoelectron spectroscopy (XPS) analysis. It was confirmed that the passive film exhibited n-type semiconducting behavior in 3.5% NaCl solution with a carrier density two orders of magnitude less than that formed on pure aluminum electrode. The XPS analysis indicated that the passive film was mainly composed of AlO(OH) after immersion for long time and the content of Mn was negligible in the outer part of the passive film. Based on the EIS measurement, electronic structure and composition analysis of the passive film, a double-layer structure, with a compact inner oxide and a porous outer layer, of the film was proposed for understanding the corrosion process of passive film, with which the experimental observations might be satisfactorily interpreted.

Nicotinic acid as a nontoxic corrosion inhibitor for hot dipped Zn and Zn-Al alloy coatings on steels in diluted hydrochloric acid

Energy Technology Data Exchange (ETDEWEB)

Ju Hong [Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China); Graduate School, Chinese Academy of Sciences, Beijing 100039 (China); Li Yan [Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China)], E-mail: yanlee@ms.qdio.ac.cn

2007-11-15

The inhibition effect of nicotinic acid for corrosion of hot dipped Zn and Zn-Al alloy coatings in diluted hydrochloric acid was investigated using quantum chemistry analysis, weight loss test, electrochemical measurement, and scanning electronic microscope (SEM) analysis. Quantum chemistry calculation results showed that nicotinic acid possessed planar structure with a number of active centers, and the populations of the Mulliken charge, the highest occupied molecular orbital (HOMO), and the lowest unoccupied molecular orbital (LUMO) were found mainly focused around oxygen and nitrogen atoms, and the cyclic of the benzene as well. The results of weight loss test and electrochemical measurement indicated that inhibition efficiency (IE%) increased with inhibitor concentration, and the highest inhibition efficiency was up to 96.7%. The corrosion inhibition of these coatings was discussed in terms of blocking the electrode reaction by adsorption of the molecules at the active centers on the electrode surface. It was found that the adsorption of nicotinic acid on coating surface followed Langmuir adsorption isotherm with single molecular layer, and nicotinic acid adsorbed on the coating surface probably by chemisorption. Nicotinic acid, therefore, can act as a good nontoxic corrosion inhibitor for hot dipped Zn and Zn-Al alloy coatings in diluted hydrochloric acid solution.

Influence of Al doping on structural and optical properties of Mg–Al co-doped ZnO thin films prepared by sol–gel method

International Nuclear Information System (INIS)

Fang, Dongyu; Lin, Kui; Xue, Tao; Cui, Can; Chen, Xiaoping; Yao, Pei; Li, Huijun

2014-01-01

Highlights: • Mg–Al co-doped ZnO thin films were prepared by sol–gel spin coating method. • The effects of Al doping on structural and optical properties of AMZO thin films were investigated. • The EDS spectra confirmed presence of Mg and Al elements in AMZO thin films. • The optical band gap of AMZO thin films increased with Al doping concentration increased. • The origin of the photoluminescence emissions was discussed. -- Abstract: Mg–Al co-doped ZnO (AMZO) thin films were successfully deposited onto quartz glass substrates by sol–gel spin coating method. The structure, surface morphology, composition, optical transmittance, and photoluminescence properties of AMZO thin films were characterized through X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy, UV–VIS–NIR spectrophotometry, and fluorescence spectrophotometry. The results indicated that AMZO thin films exhibited preferred orientation growth along the c-axis, and the full width at half maximum of the (0 0 2) diffraction peak decreased first and subsequently increased, reaching a minimum of approximately 0.275° at 3% Al content. The calculated crystallite size increased from 30.21 nm to 40.73 nm. Al doping content increased from 1% to 3% and subsequently reached 19.33 nm for Al doping content at 5%. The change in lattice parameters was demonstrated by the c/a ratio, residual stress, bond length, and volume per unit cell. EDS analysis confirmed the presence of Mg and Al elements in ZnO thin films. The atomic percentage of Mg and Al elements was nearly equal to their nominal stoichiometry within the experimental error. In addition, the optical transmittance of AMZO thin films was over 85% in the visible region, and the optical band gap increased with increasing Al doping concentration. Room temperature photoluminescence showed ultraviolet emission peak and defect emission peak. The defect emission peak of

ZnO/Al{sub 2}O{sub 3} coatings for the photoprotection of polycarbonate

Energy Technology Data Exchange (ETDEWEB)

Moustaghfir, A. [Laboratoire des Materiaux Inorganiques, UMR CNRS 6002, Universite Blaise Pascal (Clermont-Fd), 63177 Aubiere Cedex (France); Tomasella, E. [Laboratoire des Materiaux Inorganiques, UMR CNRS 6002, Universite Blaise Pascal (Clermont-Fd), 63177 Aubiere Cedex (France); Jacquet, M. [Laboratoire des Materiaux Inorganiques, UMR CNRS 6002, Universite Blaise Pascal (Clermont-Fd), 63177 Aubiere Cedex (France)]. E-mail: jacquet@chimie.univ-bpclermont.fr; Rivaton, A. [Laboratoire de Photochimie Moleculaire et Macromoleculaire, UMR CNRS 6505, Universite Blaise Pascal (Clermont-Fd), 63177 Aubiere Cedex (France); Mailhot, B. [Laboratoire de Photochimie Moleculaire et Macromoleculaire, UMR CNRS 6505, Universite Blaise Pascal (Clermont-Fd), 63177 Aubiere Cedex (France); Gardette, J.L. [Laboratoire de Photochimie Moleculaire et Macromoleculaire, UMR CNRS 6505, Universite Blaise Pascal (Clermont-Fd), 63177 Aubiere Cedex (France); Beche, E. [PROMES, Odeillo, 66125 Font-Romeu Cedex (France)

2006-10-25

ZnO and ZnO/Al{sub 2}O{sub 3} thin films were deposited by r.f. magnetron sputtering on polycarbonate (PC) films in order to protect this polymer against photodegradation. The composition, structure and optical properties of the ceramic coatings were characterised. CO{sub 2}-plasma treatments were applied to PC in order to improve the coating adhesion. The PC surface energy was characterised by wettability measurements and the chemical bonds were analysed by XPS. It was found that ZnO coatings improve the stability of PC to UV radiations and that an intermediate alumina coating inhibits the photocatalytic oxidation of PC at the PC/ZnO interface. Additionally an external alumina coating brings a high hardness to the coating.

Recombination luminescence and trap levels in undoped and Al-doped ZnO thin films on quartz and GaSe (0 0 0 1) substrates

Energy Technology Data Exchange (ETDEWEB)

Evtodiev, I. [Moldova State University, 60 A. Mateevici Str., Chisinau, MD 2009, Republic of Moldova (Moldova, Republic of); Caraman, I. [Vasile Alecsandri University of Bacau, 157 Calea Marasesti, RO 600115 Bacau (Romania); Leontie, L., E-mail: lleontie@uaic.ro [Alexandru Ioan Cuza University of Iasi, Bd. Carol I, Nr. 11, RO 700506 Iasi (Romania); Rusu, D.-I. [Vasile Alecsandri University of Bacau, 157 Calea Marasesti, RO 600115 Bacau (Romania); Dafinei, A. [Faculty of Physics, University of Bucharest, Platforma Magurele, Str. Fizicienilor nr. 1, CP Mg - 11, Bucharest-Magurele, RO 76900 (Romania); Nedeff, V.; Lazar, G. [Vasile Alecsandri University of Bacau, 157 Calea Marasesti, RO 600115 Bacau (Romania)

2012-03-15

Highlights: Black-Right-Pointing-Pointer ZnO films on GaSe create electron trapping states and PL recombination levels. Black-Right-Pointing-Pointer Zn and Al diffusion in GaSe produces low-energy widening of its PL emission. Black-Right-Pointing-Pointer ZnO:Al films on GaSe lamellas are suitable for gas-discharge lamp applications. -- Abstract: Photoluminescence spectra of ZnO and ZnO:Al (1.00, 2.00 and 5.00 at.%) films on GaSe (0 0 0 1) lamellas and amorphous quartz substrates, obtained by annealing, at 700 K, of undoped and Al-doped metal films, are investigated. For all samples, the nonequilibrium charge carriers recombine by radiative band-to-band transitions with energy of 3.27 eV, via recombination levels created by the monoionized oxygen atoms, forming the impurity band laying in the region 2.00 - 2.70 eV. Al doping induces an additional recombination level at 1.13 eV above the top of the valence band of ZnO films on GaSe substrates. As a result of thermal diffusion of Zn and Al into the GaSe interface layer from ZnO:Al/GaSe heterojunction, electron trap levels located at 0.22 eV and 0.26 eV below the conduction band edge of GaSe, as well as a deep recombination level, responsible for the luminescent emission in the region 1.10 - 1.40 eV, are created.

Spectrum designation and effect of Al substitution on the luminescence of Cr3+ doped ZnGa2O4 nano-sized phosphors

International Nuclear Information System (INIS)

Zhang Weiwei; Zhang Junying; Chen Ziyu; Wang Tianmin; Zheng Shukai

2010-01-01

Low-temperature photoluminescent spectra of ZnGa 2 O 4 :Cr 3+ nano-sized phosphors calcined at different temperatures were reported. The fine structure of the emission spectra has been designated to Cr 3+ ions in different sites including ideal octahedral, Zn-interstitial, Ga ZN 4 -Zn Ga 6 sites and Ga 2 O 3 impurity. The vibronic sidebands for both Stokes' and anti-Stokes' sides are related to the host lattice vibrations, which were confirmed by IR and Raman spectra. Al 3+ is substituted in Ga 3+ sites to form Zn(Ga 1-y Al y ) 2 O 4 :Cr 0.01 3+ (0≤y≤0.5). The blue shift and luminescent intensity variations of the charge transfer band and 3d-3d transitions in the spectra caused by Al substitution were related to larger band gap and stronger crystal field, respectively. The calculated crystal-field parameters indicated that Al incorporation enhanced the crystal field strength and induced more trigonal distortion due to different radii of Al 3+ and Ga 3+ .

Optimization of the heat and mechanical treatment of the Al-Zn-Mg-Li alloy

Directory of Open Access Journals (Sweden)

M. Stegliński

2010-07-01

Full Text Available In terms of high strength in relation to mass the alloys of aluminium – lithium find more and more use mainly in aircraft industry like inspacecraft. At present intensive investigations are carried out in aim of use of Al – Li in automotive industry in particular to components subject to fatigue wear. It could contribute to replace transmission’s elements made from traditional materials by aluminium - lithium alloys. However low resistance to wear due to forming of thin Al2O3 layer which is reproducing in friction contact disqualifies using aluminium alloys in friction contact. From this point of view first stage of investigation was to enhance hardness properties of the substrate by applying thermo-mechanical treatment.In this article the results of heat treatment of Al-Zn-Mg-Li alloy were presented. During investigations optimum parameters (timetemperature of the solution heat treatment were elaborated. Micro hardness on the cross-section were investigated. Phase, chemicalcomposition and morphology were determined. It was found that hardness after thermo-mechanical treatment of Al-Zn-Mg-Li is about20% higher than for AlCu4Mg1 (7075 –T6 alloy.

The influences of rare earth content on the microstructure and mechanical properties of Mg-7Zn-5Al alloy

International Nuclear Information System (INIS)

Xiao, Wenlong; Shen, Yusen; Wang, Lidong; Wu, Yaoming; Cao, Zhanyi; Jia, Shusheng; Wang, Limin

2010-01-01

The influences of rare earth (RE) on the microstructure and mechanical properties of Mg-7Zn-5Al alloy were studied. The results indicate that both the dendrite and grain size of the alloy can be refined by low RE addition. The Al 2 REZn 2 phase will be formed with increasing the RE content, however the high RE addition results in the grain coarsening in the alloy due to the decrease of the contribution of Al and Zn solutes on the grain refinement. The strengthening and weakening mechanisms caused by RE addition only lead to the obviously improve on the room temperature ultimate tensile strength. The mechanical properties of the studied alloys can be improved by aging treatment, and the aged Mg-7Zn-5Al-2RE alloy exhibits optimal mechanical properties at room temperature.

Synthesis and luminescence properties of ZnAl{sub 2}O{sub 4}:RE{sup 3+} (RE = Eu, Sm) phosphors

Energy Technology Data Exchange (ETDEWEB)

Lee, Seung Jin; Cho, Shin Ho [Silla University, Busan (Korea, Republic of)

2014-01-15

ZnAl{sub 2}O{sub 4}:RE{sup 3+} (RE = Eu or Sm) phosphor powders were synthesized with different concentrations of activator ions by using the conventional solid-state reaction method. The effects of the concentration of activator ions on the structural, morphological, and luminescent properties of zinc aluminate phosphors were investigated. The X-ray diffraction patterns revealed that the phosphors synthesized with different concentrations of activator ions showed mixed phases of ZnAl{sub 2}O{sub 4}, ZnO, and Al{sub 2}O{sub 3}. The crystallite size was estimated using the Scherrer formula, and the maximum size was obtained for 0.20 mol of Eu{sup 3+} ions. The emission spectra of of Eu{sup 3+}-doped ZnAl{sub 2}O{sub 4} phosphors under excitation at 303 nm exhibited one intense green band at approximately 520 nm and three weak bands centered at 590, 621, and 701 nm, respectively. The intensity of all the emission bands reached a maximum for 0.05 mol of Eu{sup 3+} ions. For the Sm{sup 3+}-doped ZnAl{sub 2}O{sub 4} phosphors, a broad emission band peak at 526 nm and several weak lines in the range 470 - 700 nm were observed. The results suggest that the luminescent intensity of the phosphors can be enhanced by controlling the amount of activator ions incorporated into the host lattice.

Enhanced magnetic properties in ZnCoAlO caused by exchange-coupling to Co nanoparticles

International Nuclear Information System (INIS)

Feng, Qi; Dizayee, Wala; Li, Xiaoli; Score, David S; Neal, James R; Behan, Anthony J; Mokhtari, Abbas; Alshammari, Marzook S; Al-Qahtani, Mohammed S; Blythe, Harry J; Fox, A Mark; Gehring, Gillian A; Chantrell, Roy W; Heald, Steve M; Xu, Xiao-Hong

2016-01-01

We report the results of a sequence of magnetisation and magneto-optical studies on laser ablated thin films of ZnCoAlO and ZnCoO that contain a small amount of metallic cobalt. The results are compared to those expected when all the magnetization is due to isolated metallic clusters of cobalt and with an oxide sample that is almost free from metallic inclusions. Using a variety of direct magnetic measurements and also magnetic circular dichroism we find that there is ferromagnetism within both the oxide and the metallic inclusions, and furthermore that these magnetic components are exchange-coupled when aluminium is included. This enhances both the coercive field and the remanence. Hence the presence of a controlled quantity of metallic nanoparticles in ZnAlO can improve the magnetic response of the oxide, thus giving great advantages for applications in spintronics. (paper)

Effect of annealing on silicon heterojunction solar cells with textured ZnO:Al as transparent conductive oxide

Directory of Open Access Journals (Sweden)

Roca i Cabarrocas P.

2012-07-01

Full Text Available We report on silicon heterojunction solar cells using textured aluminum doped zinc oxide (ZnO:Al as a transparent conductive oxide (TCO instead of flat indium tin oxide. Double side silicon heterojunction solar cell were fabricated by radio frequency plasma enhanced chemical vapor deposition on high life time N-type float zone crystalline silicon wafers. On both sides of these cells we have deposited by radio frequency magnetron sputtering ZnO:Al layers of thickness ranging from 800 nm to 1400 nm. These TCO layers were then textured by dipping the samples in a 0.5% hydrochloric acid. External quantum efficiency as well as I-V under 1 sun illumination measurements showed an increase of the current for the cells using textured ZnO:Al. The cells were then annealed at 150 °C, 175 °C and 200 °C during 30 min in ambient atmosphere and characterized at each annealing step. The results show that annealing has no impact on the open circuit voltage of the devices but that up to a 175 °C it enhances their short circuit current, consistent with an overall enhancement of their spectral response. Our results suggest that ZnO:Al is a promising material to increase the short circuit current (Jsc while avoiding texturing the c-Si substrate.

Evaluation of mechanical hardness and fracture toughness of Co and Al co-doped ZnO

International Nuclear Information System (INIS)

Siddheswaran, R.; Mangalaraja, R.V.; Avila, Ricardo E.; Manikandan, D.; Esther Jeyanthi, C.; Ananthakumar, S.

2012-01-01

Combustion synthesized nanocrystalline Co and Al co-doped ZnO powders [(Zn 1−x−y Co x Al y O; x=0.04, 0.03, 0.02; y=0.01, 0.02, 0.03)] were fabricated into cylindrical discs by uni-axial pressing and sintered intentionally at 1000 °C for 2 h to assess the mechanical performance. The crystallinity of the pure and doped ZnO was confirmed by X-ray diffraction analysis. The microstructures of the sintered samples were investigated by scanning electron microscopy (SEM) to examine the density, porosity, grain size and its distribution. Grains of 0.5–3 μm were observed for the samples sintered at 1000 °C. The mechanical properties such as micro-hardness, fracture toughness and strain hardening co-efficient were investigated by the Vickers indentation method. It was found that the crack mode observed during the indentation on the samples belongs to median cracks under a load of 19.6 N. Also, the hardness was enhanced with increasing mol% of Co, while the trend was reversed with the increase of Al content. In addition, the strain hardening coefficient and fracture toughness were calculated using the indentation data.

Co2+ adsorption in porous oxides Mg O, Al2O3 and Zn O

International Nuclear Information System (INIS)

Moreno M, J. E.; Granados C, F.; Bulbulian, S.

2009-01-01

The porous oxides Mg O, Al 2 O 3 and Zn O were synthesized by the chemical combustion in solution method and characterized be means of scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The adsorption behavior of Co 2+ ions present in aqueous solution were studied on the synthesized materials by means of experiments lots type to ambient temperature. It was found that the cobalt ions removal was of 90% in Mg O, 65% in Zn O and 72% in Al 2 O 3 respectively, indicating that the magnesium oxide is the best material to remove Co 2+ presents in aqueous solution. (Author)

Co-sequestration of Zn(II) and phosphate by γ-Al{sub 2}O{sub 3}: From macroscopic to microscopic investigation

Energy Technology Data Exchange (ETDEWEB)

Ren, Xuemei [School of Environment and Chemical Engineering, North China Electric Power University, Beijing 102206 (China); Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, 230031, Hefei (China); Tan, Xiaoli [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, 230031, Hefei (China); Hayat, Tasawar [Department of Mathematics, Quaid-I-Azam University, Islamabad 44000 (Pakistan); NAAM Research Group, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Alsaedi, Ahmed [NAAM Research Group, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Wang, Xiangke, E-mail: xkwang@ipp.ac.cn [School of Environment and Chemical Engineering, North China Electric Power University, Beijing 102206 (China); NAAM Research Group, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions (China)

2015-10-30

Highlights: • How the Zn and phosphate behave in each other’s presence is elucidated. • Surface speciation of Zn(II) is affected by the presence of phosphate. • Combining macroscopic study with EXAFS can determine the Zn(II) surface speciation. • The enhanced Zn(II) sorption is mainly due to ternary surface complexation at 0.19 mmol P/L and pH 6.5. • Phosphate ions prevent the formation of an Zn–Al LDH phase at pH 8.0. - Abstract: Little information is available concerning co-sorbing oxyanion and metal contaminants in the environment, yet in most metal-contaminated areas, co-contamination by phosphate is common. In this study, the mutual effects of phosphate and Zn(II) on their interaction with γ-Al{sub 2}O{sub 3} are investigated by batch experiments and X-ray absorption fine structure spectroscopy (XAFS) technique. The results show that the co-sorption of phosphate on γ-Al{sub 2}O{sub 3} modifies both the extent of Zn(II) sorption and the local atomic structures of sorbed Zn(II) ions. Multiple mechanisms are involved in Zn(II) retention in the presence of phosphate, including electrostatic interaction, binary and ternary surface complexation, and the formation of Zn(II)-phosphate polynuclear complexes. At pH 6.5, type III ternary surface complexation occurs concurrently with binary Zn-alumina surface complexation at low phosphate concentrations, whereas the formation of type III ternary surface complexes is promoted as the phosphate concentration increases. With further increasing phosphate concentration, Zn(II)-phosphate polynuclear complexes are formed. At pH 8.0, Zn dominantly forms type III ternary surface complexes in the presence of phosphate. The results of this study indicate the variability of Zn complexation on oxide surface and the importance of combining macroscopic observations with XAFS capable of determining metal complex formation mechanism for ternary system.

Ultra-precision machining induced phase decomposition at surface of Zn-Al based alloy

International Nuclear Information System (INIS)

To, S.; Zhu, Y.H.; Lee, W.B.

2006-01-01

The microstructural changes and phase transformation of an ultra-precision machined Zn-Al based alloy were examined using X-ray diffraction and back-scattered electron microscopy techniques. Decomposition of the Zn-rich η phase and the related changes in crystal orientation was detected at the surface of the ultra-precision machined alloy specimen. The effects of the machining parameters, such as cutting speed and depth of cut, on the phase decomposition were discussed in comparison with the tensile and rolling induced microstrucutural changes and phase decomposition

Decreased Charge Transport Barrier and Recombination of Organic Solar Cells by Constructing Interfacial Nanojunction with Annealing-Free ZnO and Al Layers.

Science.gov (United States)

Liu, Chunyu; Zhang, Dezhong; Li, Zhiqi; Zhang, Xinyuan; Guo, Wenbin; Zhang, Liu; Ruan, Shengping; Long, Yongbing

2017-07-05

To overcome drawbacks of the electron transport layer, such as complex surface defects and unmatched energy levels, we successfully employed a smart semiconductor-metal interfacial nanojunciton in organic solar cells by evaporating an ultrathin Al interlayer onto annealing-free ZnO electron transport layer, resulting in a high fill factor of 73.68% and power conversion efficiency of 9.81%. The construction of ZnO-Al nanojunction could effectively fill the surface defects of ZnO and reduce its work function because of the electron transfer from Al to ZnO by Fermi level equilibrium. The filling of surface defects decreased the interfacial carrier recombination in midgap trap states. The reduced surface work function of ZnO-Al remodulated the interfacial characteristics between ZnO and [6,6]-phenyl C71-butyric acid methyl ester (PC 71 BM), decreasing or even eliminating the interfacial barrier against the electron transport, which is beneficial to improve the electron extraction capacity. The filled surface defects and reduced interfacial barrier were realistically observed by photoluminescence measurements of ZnO film and the performance of electron injection devices, respectively. This work provides a simple and effective method to simultaneously solve the problems of surface defects and unmatched energy level for the annealing-free ZnO or other metal oxide semiconductors, paving a way for the future popularization in photovoltaic devices.

Effect of aging on the martensitic transformation temperature in Ag-Zn-Al alloys

International Nuclear Information System (INIS)

Takezawa, K.; Hoshi, H.; Marukawa, K.

2000-01-01

The relation between atomic ordering and martensitic transformation temperature, M s , in Ag-Zn-Al alloys was examined mainly by means of electrical resistivity measurements. Disordered bcc phase was frozen-in by quenching from a temperature above the critical temperature for ordering, T c . In a Ag-22.3at%Zn-8.9at%Al alloy, the M s temperature has been found to decrease by aging in the parent phase at temperatures between 253 and 293 K. The resistivity also decreased in accord with the M s temperature. This indicates that atomic ordering proceeds by aging. The relation between the decrease in the reverse transformation temperature, A f , and the degree of long range order was obtained. In a Ag-11.0at%Zn-15.5at%Al alloy, in which the M s temperature in the as-quenched state is higher and the T c temperature is lower than that of the former alloy, aging in the martensite phase was performed. In this case, the aging brought about the increase in the A f temperature. This is in contrast to the results of aging in the parent phase. Furthermore, the effect of aging in the parent phase at temperatures higher than T c was examined. Both the transformation temperature and the resistivity were found to become higher. These changes are due to lowering in the degree of short range order. (orig.)

Enhanced diffusion of Zn in Al under Ne irradiation

International Nuclear Information System (INIS)

Myers, S.M.

1975-01-01

The diffusion rate of Zn in Al has been enhanced by factors approximately 10 2 --10 4 under 80 keV Ne irradiation at 130 0 C. Diffusion couples were formed by ion implantation of Zn, and the concentration profiles were determined by ion backscattering. The data are analyzed by numerically solving the coupled diffusion equations for vacancies, interstitials and atoms, and by scaling the profiles of vacancy and interstitial production rates from the theoretical profile of Ne energy into atomic processes. The enhanced diffusion rate is linear in flux, indicating that the mobile point defects annihilate predominantly at fixed sinks. The average distance to annihilation is approximately 700 A, except for the first approximately 500 A of the solid where it is much less. Free vacancies and interstitials are found to be created by the Ne at a smaller rate than the atomic displacement rate, suggesting a high annihilation probability within the parent damage cascade

Temperature dependence of microstructure and strain evolution in strained ZnO films on Al2O3(0001)

International Nuclear Information System (INIS)

Kim, In-Woo; Lee, Kyu-Mann

2008-01-01

We have studied the temperature dependence of the growth mode and microstructure evolution in highly mismatched sputter-grown ZnO/Al 2 O 3 (0001) heteroepitaxial films. The growth mode was studied by real-time synchrotron x-ray scattering. We find that the growth mode changes from a two-dimensional (2D) layer to a 3D island in the early growth stage with temperature (300-600 deg. C), in sharp contrast to the reported transition from three dimensions to two dimensions in metal-organic vapor phase epitaxy. At around 400 deg. C intermediate 2D platelets nucleate in the early stage, which act as nucleation cores of 3D islands and transform to a misaligned state during further growth. Meanwhile, at high temperature (above 500 deg. C), the spinel structure of ZnAl 2 O 4 grows in the early stage, and it undergoes a transition to wurtzite-ZnO (w-ZnO) with thickness. The spinel formation is presumably driven by high temperature and large incident energy of impacting atoms during sputtering. The results of the strain evolution as functions of temperature and thickness during growth suggest that the surface diffusion is a major factor determining the microstructural properties in the strained ZnO/Al 2 O 3 (0001) heteroepitaxy

Hardening mechanisms of spray formed Al-Zn-Mg-Cu alloys with scandium and other elemental additions

International Nuclear Information System (INIS)

Sharma, M.M.; Amateau, M.F.; Eden, T.J.

2006-01-01

The hardening mechanisms in spray formed Al-Zn-Mg-Cu alloys with additions of chromium, zinc and scandium were studied. The microstructure of the spray formed alloys was analyzed by transmission electron microscopy. A range of tensile strengths were achieved, and varied based on elemental additions, and second phase particle strengthening. To explain the significantly higher strength in one alloy with scandium, theoretical results due to the yield stress of Al-Zn-Mg-Cu alloys as a function of volume fraction and precipitate particle size, were compared to experimental data. Both the possibilities of coherency and order strengthening are examined. The significant additional hardening achieved in the alloy with scandium is attributed to small ordered particles of Al 3 Sc, which precipitated during aging

Effect of Ce-rich rare earth on microstructure and mechanical properties of Mg-10Zn-5Al-0.1Sb magnesium alloy

Directory of Open Access Journals (Sweden)

You Zhiyong

2012-05-01

Full Text Available To improve the comprehensive mechanical properties of Mg-10Zn-5Al-0.1Sb magnesium alloy, different amount of Ce-rich rare earth (RE was added to the alloy, and the effect of RE addition on the microstructure and mechanical properties of Mg-10Zn-5Al-0.1Sb alloy was investigated by means of Brinell hardness measurement, scanning electron microscopy (SEM, energy dispersive spectroscope (EDS and X-ray diffraction (XRD. The results show that an appropriate amount of Ce-rich rare earth addition can make the Al4Ce phase particles and CeSb phase disperse more evenly in the alloy. These phases refine the alloy抯 matrix and make the secondary phases [t-Mg32(Al,Zn49 phase and f-Al2Mg5Zn2 phase] finer and more dispersive, therefore significantly improve the mechanical properties of the Mg-10Zn-5Al-0.1Sb alloy. When the RE addition is 1.0 wt.%, the tensile strengths of the alloy both at room temperature and 150 篊 reach the maximum values while the impact toughness is slightly lower than that of the matrix alloy. The hardness increases with the increase of RE addition.

Highly transparent and conductive Sn/F and Al co-doped ZnO thin films prepared by sol–gel method

International Nuclear Information System (INIS)

Pan, Zhanchang; Luo, Junming; Tian, Xinlong; Wu, Shoukun; Chen, Chun; Deng, Jianfeng; Xiao, Chumin; Hu, Guanghui; Wei, Zhigang

2014-01-01

Highlights: • F/Sn and Al co-doped ZnO thin films were synthesized by sol–gel method. • The co-doped nanocrystals exhibit good crystal quality. • The origin of the photoluminescence emissions was discussed. • The films showed high transmittance and low resistivity. -- Abstract: Al doped ZnO, Al–Sn co-doped ZnO and Al–F co-doped ZnO nanocrystals were successfully synthesized onto glass substrates by the sol–gel method. The structure and morphology of the films are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The results indicated that all the films were polycrystalline with a hexagonal wurtzite structure and exhibited a c-axis preferred orientation. The electrical and optical properties were also investigated by 4-point probe device and Uv–vis spectroscopy, room temperature photoluminescence (PL) and Raman spectrum (Raman), respectively. The PL and Raman results suggested that the co-doped films with a very low defect concentration and exhibit a better crystallinity than AZO thin films. The XPS study confirmed the incorporation of Al, Sn and F ions in the ZnO lattice

Advanced properties of Al-doped ZnO films with a seed layer approach for industrial thin film photovoltaic application

International Nuclear Information System (INIS)

Dewald, Wilma; Sittinger, Volker; Szyszka, Bernd; Säuberlich, Frank; Stannowski, Bernd; Köhl, Dominik; Ries, Patrick; Wuttig, Matthias

2013-01-01

Currently sputtered Al-doped ZnO films are transferred to industry for the application in thin film silicon solar modules. These films are known to easily form light trapping structures upon etching which are necessary for absorbers with low absorbance such as μc-Si. Up to now the best structures for high efficiency thin film silicon solar cells were obtained by low rate radio frequency (r.f.) sputtering of ceramic targets. However, for industrial application a high rate process is essential. Therefore a seed layer approach was developed to increase the deposition rate while keeping the desired etch morphology and electrical properties. Aluminum doped ZnO films were deposited dynamically by direct current (d.c.) magnetron sputtering from a ceramic ZnO:Al 2 O 3 target (1 wt.%) onto an additional seed layer prepared by r.f. sputtering. ZnO:Al films were investigated with respect to their optical and electrical properties as well as the morphology created after etching for a-Si/μc-Si solar cells. Additionally atomic force microscopy, scanning electron microscopy, X-ray diffraction and Hall measurements were performed, comparing purely r.f. or d.c. sputtered films with d.c. sputtered films on seed layers. With the seed layer approach it was possible to deposit ZnO:Al films with a visual transmittance of 83.5%, resistivity of 295 μΩ cm, electron mobility of 48.9 cm 2 /Vs and electron density of 4.3 · 10 20 cm −3 from a ceramic target at 330 °C. Etch morphologies with 1 μm lateral structure size were achieved. - Highlights: ► Seed layer approach for dynamic sputter deposition of enhanced quality ZnO:Al. ► A thin radio frequency sputtered ZnO:Al layer assists film nucleation on glass. ► Electron mobility was increased up to 49 cm 2 /Vs due to quasi-epitaxial film growth. ► Etch morphology exhibits 1 μm wide craters for light trapping in solar cells. ► The concept was transferred to a seed layer sputtered with direct current

Advanced properties of Al-doped ZnO films with a seed layer approach for industrial thin film photovoltaic application

Energy Technology Data Exchange (ETDEWEB)

Dewald, Wilma, E-mail: wilma.dewald@ist.fraunhofer.de [Fraunhofer Institute for Surface Engineering and Thin Films IST, Bienroder Weg 54E, 38108 Braunschweig (Germany); Sittinger, Volker; Szyszka, Bernd [Fraunhofer Institute for Surface Engineering and Thin Films IST, Bienroder Weg 54E, 38108 Braunschweig (Germany); Säuberlich, Frank; Stannowski, Bernd [Sontor GmbH, OT Thalheim, Sonnenallee 7-11, 06766 Bitterfeld-Wolfen (Germany); Köhl, Dominik; Ries, Patrick; Wuttig, Matthias [I. Physikalisches Institut (IA), RWTH Aachen, Sommerfeldstraße 14, 52074 Aachen (Germany)

2013-05-01

Currently sputtered Al-doped ZnO films are transferred to industry for the application in thin film silicon solar modules. These films are known to easily form light trapping structures upon etching which are necessary for absorbers with low absorbance such as μc-Si. Up to now the best structures for high efficiency thin film silicon solar cells were obtained by low rate radio frequency (r.f.) sputtering of ceramic targets. However, for industrial application a high rate process is essential. Therefore a seed layer approach was developed to increase the deposition rate while keeping the desired etch morphology and electrical properties. Aluminum doped ZnO films were deposited dynamically by direct current (d.c.) magnetron sputtering from a ceramic ZnO:Al{sub 2}O{sub 3} target (1 wt.%) onto an additional seed layer prepared by r.f. sputtering. ZnO:Al films were investigated with respect to their optical and electrical properties as well as the morphology created after etching for a-Si/μc-Si solar cells. Additionally atomic force microscopy, scanning electron microscopy, X-ray diffraction and Hall measurements were performed, comparing purely r.f. or d.c. sputtered films with d.c. sputtered films on seed layers. With the seed layer approach it was possible to deposit ZnO:Al films with a visual transmittance of 83.5%, resistivity of 295 μΩ cm, electron mobility of 48.9 cm{sup 2}/Vs and electron density of 4.3 · 10{sup 20} cm{sup −3} from a ceramic target at 330 °C. Etch morphologies with 1 μm lateral structure size were achieved. - Highlights: ► Seed layer approach for dynamic sputter deposition of enhanced quality ZnO:Al. ► A thin radio frequency sputtered ZnO:Al layer assists film nucleation on glass. ► Electron mobility was increased up to 49 cm{sup 2}/Vs due to quasi-epitaxial film growth. ► Etch morphology exhibits 1 μm wide craters for light trapping in solar cells. ► The concept was transferred to a seed layer sputtered with direct current.

Rapid ultrasound-induced transient-liquid-phase bonding of Al-50Si alloys with Zn interlayer in air for electrical packaging application.

Science.gov (United States)

Wang, Qian; Chen, Xiaoguang; Zhu, Lin; Yan, Jiuchun; Lai, Zhiwei; Zhao, Pizhi; Bao, Juncheng; Lv, Guicai; You, Chen; Zhou, Xiaoyu; Zhang, Jian; Li, Yuntao

2017-01-01

Al-50Si alloys were joined by rapid ultrasound-induced transient-liquid-phase bonding method using Zn foil as interlayer at 390°C in air, below the melt point of interlayer. The fracture of oxide films along the edge of Si particles led to contact and inter-diffusion between aluminum substrate and Zn interlayer, and liquefied Zn-Al alloys were developed. The width of Zn-Al alloys gradually decreased with increasing the ultrasonic vibration time due to liquid squeezing out and accelerated diffusion. A stage of isothermal solidification existed, and the completion time was significantly shortened. In the liquid metal, the acoustic streaming and ultrasonic cavitations were induced. As the process developed, much more Si particles, which were particulate-reinforced phases of Al-50Si, gradually migrated to the center of soldering seam. The highest average shear strength of joints reached to 94.2MPa, and the fracture mainly occurred at the base metal. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication of n-ZnO/ p-Si (100) and n-ZnO:Al/ p-Si (100) Heterostructures and Study of Current-Voltage, Capacitance-Voltage and Room-Temperature Photoluminescence

Science.gov (United States)

Shah, M. A. H.; Khan, M. K. R.; Tanveer Karim, A. M. M.; Rahman, M. M.; Kamruzzaman, M.

2018-01-01

Heterojunction diodes of n-ZnO/ p-Si (100) and n-ZnO:Al/ p-Si (100) were fabricated by spray pyrolysis technique. X-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDX), and field emission scanning electron microscopy (FESEM) were used to characterize the as-prepared samples. The XRD pattern indicates the hexagonal wurzite structure of zinc oxide (ZnO) and Al-doped ZnO (AZO) thin films grown on Si (100) substrate. The compositional analysis by EDX indicates the presence of Al in the AZO structure. The FESEM image indicates the smooth and compact surface of the heterostructures. The current-voltage characteristics of the heterojunction confirm the rectifying diode behavior at different temperatures and illumination intensities. For low forward bias voltage, the ideality factors were determined to be 1.24 and 1.38 for un-doped and Al-doped heterostructures at room temperature (RT), respectively, which indicates the good diode characteristics. The capacitance-voltage response of the heterojunctions was studied for different oscillation frequencies. From the 1/ C 2- V plot, the junction built-in potentials were found 0.30 V and 0.40 V for un-doped and Al-doped junctions at RT, respectively. The differences in built-in potential for different heterojunctions indicate the different interface state densities of the junctions. From the RT photoluminescence (PL) spectrum of the n-ZnO/ p-Si (100) heterostructure, an intense main peak at near band edge (NBE) 378 nm (3.28 eV) and weak deep-level emissions (DLE) centered at 436 nm (2.84 eV) and 412 nm (3.00 eV) were observed. The NBE emission is attributed to the radiative recombination of the free and bound excitons and the DLE results from the radiative recombination through deep level defects.

Effect Of SiC Particles On Sinterability Of Al-Zn-Mg-Cu P/M Alloy

Directory of Open Access Journals (Sweden)

Rudianto H.

2015-06-01

Full Text Available Premix Al-5.5Zn-2.5Mg-0.5Cu alloy powder was analyzed as matrix in this research. Gas atomized powder Al-9Si with 20% volume fraction of SiC particles was used as reinforcement and added into the alloy with varied concentration. Mix powders were compacted by dual action press with compaction pressure of 700 MPa. High volume fraction of SiC particles gave lower green density due to resistance of SiC particles to plastic deformation during compaction process and resulted voids between particles and this might reduce sinterability of this mix powder. Sintering was carried out under ultra high purity nitrogen gas from 565°-580°C for 1 hour. High content of premix Al-5.5Zn-2.5Mg-0.5Cu alloy powder gave better sintering density and reached up to 98% relative. Void between particles, oxide layer on aluminum powder and lower wettability between matrix and reinforcement particles lead to uncompleted liquid phase sintering, and resulted on lower sintering density and mechanical properties on powder with high content of SiC particles. Mix powder with wt90% of Alumix 431D and wt10% of Al-9Si-vf20SiC powder gave higher tensile strength compare to another mix powder for 270 MPa. From chemical compositions, sintering precipitates might form after sintering such as MgZn2, CuAl2 and Mg2Si. X-ray diffraction, DSC-TGA, and SEM were used to characterize these materials.

Early-stage precipitation in Al-Zn-Mg-Cu alloy (7050)

International Nuclear Information System (INIS)

Sha Gang; Cerezo, Alfred

2004-01-01

GP zone and metastable η ' formation during the early-stage precipitation of a 7050 Al alloy aged at 121 deg. C has been investigated using transmission electron microscopy, together with 3-dimensional atom probe analysis (of the chemistry and morphology) of individual precipitates. Small Mg-rich clusters (GPI zones) are found in the alloy after short ageing times at 121 deg. C, together with larger GPI zones (Zn/Mg=1.0). Zn-rich η ' platelets are seen to form mainly between 30 and 240 min ageing, coexisting with larger GPI zones. A significant fraction of elongated clusters have also been observed over this period of ageing. The dominant mechanism for η ' formation at this stage is shown to be by transformation of small GPI zones, via these elongated clusters and not by nucleation on larger zones

Phosgene-free synthesis of hexamethylene-1,6-diisocyanate by the catalytic decomposition of dimethylhexane-1,6-dicarbamate over zinc-incorporated berlinite (ZnAlPO{sub 4})

Energy Technology Data Exchange (ETDEWEB)

Sun, Da-Lei [Department of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China); College of Chemistry and Chemical Engineering, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Luo, Jun-Yin; Wen, Ru-Yu [Department of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China); Deng, Jian-Ru [College of Chemistry and Chemical Engineering, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Chao, Zi-Sheng, E-mail: zschao@yahoo.com [College of Chemistry and Chemical Engineering, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China)

2014-02-15

Highlights: • Synthesis of HDI via HDU decomposition over ZnAlPO{sub 4} heterogeneous catalyst. • Employment of self-designed reliable fixed bed reactor for HDU decomposition to HDI. • As high as 89.4% yield of HDI over ZnAlPO{sub 4} catalyst. • High stability and large ability for repeating usage of ZnAlPO{sub 4} catalyst. -- Abstract: The phosgene-free synthesis of hexamethylene-1,6-diisocyanate (HDI) by the decomposition of dimethylhexane-1,6-dicarbamate (HDU) was carried out on a self-designed fixed-bed catalytic reactor, using zinc-incorporated berlinite (ZnAlPO{sub 4}) as catalyst, dioctyl phthalate (DOP) as solvent and N{sub 2} as carrier gas. Factors influencing the yield of HDI, including the Zn/Al molar ratio, HDU concentration and liquid space velocity (LHSV), were investigated. Under the optimized reaction conditions, i.e., 4.8 wt.% concentration of HDU in DOP, 100 ml/min N{sub 2} flow rate, 0.09 MPa vacuum, 623 K reaction temperature, 1.2 h{sup −1} LHSV and catalyst usage 2.0 g, a 89.4% yield of HDI had been achieved over the ZnAlPO{sub 4} (molar ratio Zn/Al = 0.04) catalyst. The ZnAlPO{sub 4} catalyst was found to exhibit a considerable large on-stream stability and could be repeatedly used in the decomposition of HDU to HDI, after its regeneration.

Nano-ZnO Particles’ Effect in Improving the Mechanical Response of Mg-3Al-0.4Ce Alloy

Directory of Open Access Journals (Sweden)

Sravya Tekumalla

2016-11-01

Full Text Available Magnesium based nanocomposites, due to their excellent dimensional stability and mechanical integrity, have a lot of potential to replace the existing commercial Al alloys and steels used in aerospace and automotive applications. Mg-Al alloys are commercially used in the form of AZ (magnesium-aluminum-zinc and AM (magnesium-aluminum-manganese series in automobile components. However, the Mg17Al12 phase in Mg-Al alloys is a low melting phase which results in a poor creep and high temperature performance of the alloys. Rare earth additions modify the phase and hence improve the properties of the materials. In this paper, Ce and nano ZnO particles were added to Mg-Al alloys to attain a favorable effect on their properties. The developed materials exhibited promising properties in terms of thermal expansion coefficient (CTE, hardness, and tensile strength. Further, the ZnO addition refined the microstructure and helped in obtaining a uniform distribution, however without grain size refinement. The increased addition of ZnO and the improvement in the distribution led to an enhancement in the properties, rendering the materials suitable for a wide spectrum of engineering applications.

A comparative study on magnetism in Zn-doped AlN and GaN from first-principles

International Nuclear Information System (INIS)

Xu, Liang; Wang, Lingling; Huang, Weiqing; Xiao, Wenzhi; Xiao, Gang

2014-01-01

First-principles calculations have been used to comparatively investigate electronic and magnetic properties of Zn-doped AlN and GaN. A total magnetic moment of 1.0 μ B induced by Zn is found in AlN, but not in GaN. Analyses show that the origin of spontaneous polarization not only depend on the localized atomic orbitals of N and sufficient hole concentration, but also the relative intensity of the covalency of matrix. The relatively stronger covalent character of GaN with respect to AlN impedes forming local magnetic moment in GaN matrix. Our study offers a fresh sight of spontaneous spin polarization in d 0 magnetism. The much stronger ferromagnetic coupling in c-plane of AlN means that it is feasible to realize long-range ferromagnetic order via monolayer delta-doping. This can apply to other wide band-gap semiconductors in wurtzite structure.

The formation of tungsten doped Al{sub 2}O{sub 3}/ZnO coatings on aluminum by plasma electrolytic oxidation and their application in photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Stojadinović, Stevan, E-mail: sstevan@ff.bg.ac.rs [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Vasilić, Rastko [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Radić, Nenad [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia); Tadić, Nenad [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Stefanov, Plamen [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, 1113 Sofia (Bulgaria); Grbić, Boško [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia)

2016-07-30

Highlights: • Tungsten doped Al{sub 2}O{sub 3}/ZnO coatings are formed by plasma electrolytic oxidation (PEO). • Coatings are mainly composed of alpha alumina, ZnO and metallic tungsten. • Photocatalytic activity of doped Al{sub 2}O{sub 3}/ZnO coatings is higher than of undoped ones. • The increase of photoluminescence corresponds to decrease of photocatalytic activity. • Tungsten acts as a charge trap to reduce the recombination rate of electron/hole pairs. - Abstract: Tungsten doped Al{sub 2}O{sub 3}/ZnO coatings are formed by plasma electrolytic oxidation of aluminum substrate in supporting electrolyte (0.1 M boric acid + 0.05 M borax + 2 g/L ZnO) with addition of different concentrations of Na{sub 2}WO{sub 4}·2H{sub 2}O. The morphology, crystal structure, chemical composition, and light absorption characteristics of formed surface coatings are investigated. The X-ray diffraction and X-ray photoelectron spectroscopy results indicate that formed surface coatings consist of alpha and gamma phase of Al{sub 2}O{sub 3}, ZnO, metallic tungsten and WO{sub 3}. Obtained results showed that incorporated tungsten does not have any influence on the absorption spectra of Al{sub 2}O{sub 3}/ZnO coatings, which showed invariable band edge at about 385 nm. The photocatalytic activity of undoped and tungsten doped Al{sub 2}O{sub 3}/ZnO coatings is estimated by the photodegradation of methyl orange. The photocatalytic activity of tungsten doped Al{sub 2}O{sub 3}/ZnO coatings is higher thanof undoped Al{sub 2}O{sub 3}/ZnO coatings; the best photocatalytic activity is ascribed to coatings formed in supporting electrolyte with addition of 0.3 g/L Na{sub 2}WO{sub 4}·2H{sub 2}O. Tungsten in Al{sub 2}O{sub 3}/ZnO coatings acts as a charge trap, thus reducing the recombination rate of photogenerated electron-hole pairs. The results of PL measurements are in agreement with photocatalytic activity. Declining PL intensity corresponds to increasing photocatalytic activity of the

Angular distributions of fast neutrons scattered by Al, Si, P, S and Zn; Distributions angulaires des neutrons rapides diffuses par Al, Si, P, S et Zn; Usloviya raspredeleniya bystrykh nejtronov, rasseyannykh alyuminiem, kremniem, fosforom i tsinkom; Distribuciones angulares de neutrones rapidos dispersados por Al, Si, P, S y Zn

Energy Technology Data Exchange (ETDEWEB)

Tstjkaija, K; Tanaka, S; Maeuyama, M; Tomita, Y [Japan Atomic Energy Research Institute, Tokai-Mtjea (Japan)

1962-03-15

Differential scattering cross-sections of Al, Si, P, S and Zn for fast neutrons have been measured in an energy range of 3.4 to 4.6 MeV by using the time-of-flight method. Angular distributions of the inelastically scattered neutrons are nearly isotropic in all cases. These results are discussed on the basis of the Hauser-Feshbach theory. (author) [French] Les sections efficaces differentielles de diffusion de Al, Si, P, S et Zn pour des neutrons rapides ont ete mesurees dans la gamme d'energies de 3,4 a 4,6 MeV, en employant la methode du temps de vol. Les distributions angulaires des neutrons diffuses inelastiquement sont presque isotropes dans tous les cas. Les auteurs analysent ces resultats en se fondant sur la theorie de Hauser-Feshbach. (author) [Spanish] Los autores han medido por el metodo del tiempo de vuelo las secciones eficaces diferenciales de dispersion del Al, Si, P, S y Zn para neutrones rapidos de energia comprendida entre 3,4 y 4,6 MeV. Las distribuciones angulares de los neutrones dispersados inelasticamente son casi isotropicas en todos los casos. Los autores analizan los resultados obtenidos basandose en la teoria de Hauser-Feshbach . (author) [Russian] Differentsial'no e sechenie rasseyaniya alyuminiya, kremniya, fosfora, sery i tsinka dlya bystrykh nejtronov izmereno v diapazone ehnergii ot 3,4 do 4,6 Megaehlektronvol't ispol'zovanie m metoda vremeni proleta. Uglovye raspredeleniya neuprugo rasseyannykh nejtronov yavlyayutsya pochti vo vsekh sluchayakh izotropnymi. Jeti rezul'taty obsuzhdayutsya na osnove teorii Hauzera-Feshbakha. (author)

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.

INFLUENCE OF MICROSTRUCTURAL ANISOTROPY ON THE SPALLATION OF 1080 EUTECTOID STEEL

International Nuclear Information System (INIS)

GRAY, G.T.; LOPEZ, M.F.

2001-01-01

While the influence of crystallographic texture on elastic and plastic constitutive response has seen extensive investigation in recent years, the influence of texture on the dynamic fracture of engineering materials remains less extensively explored. In particular, the influence of anisotropy, both textural and morphological, on the spallation behavior of materials remains poorly quantified. In this study, the spallation response of 1080-steel has been studied as a function of microstructural morphological anisotropy. In this study the influence of elongated MnS stringers, resident within a crystallographically isotropic eutectoid steel, on the spallation response of 1080 steel was investigated. That of a fully-pearlitic 1080 steel loaded to 5 GPa was found to be dominated by the heterogeneous nucleation of damage normal and orthogonal to the MnS stringers. Delamination between the matrix pearlitic microstructure and the MnS stringers was seen to correlate to a significantly lower pull-back signal during transverse loading than to that parallel to the stringer axis. The ''pull-back'' signals and post-spallation metallographic observations are discussed with reference to the influence of microstructural anisotropy on void nucleation and growth

Thermodynamic reversibility and irreversibility of the reverse transformation in stabilized Cu-Zn-Al martensite

International Nuclear Information System (INIS)

Kustov, S.; Corro, M.; Pons, J.; Cesari, E.; Van Humbeeck, J.

2006-01-01

It has been shown that both pinning- (mechanical) and reordering-induced (chemical) stabilization components contribute to the overall stabilization effect. An algorithm has been developed for quantitative analysis of the chemical and mechanical stabilization components, using routine calorimetry results. The basic idea underlying this algorithm is that chemical and mechanical stabilization components stem, respectively, from the factors, affecting thermodynamically reversible and irreversible factors during the first reverse transformation of the stabilized martensite. On a thermodynamical level, application of the suggested algorithm has been illustrated using experimental calorimetry results for a Cu-Zn-Al alloy. Here we report analysis of pinning and reordering processes on a microscopic scale, using experimental data on non-linear anelasticity in the same Cu-Zn-Al alloy to track different spatial and temporal localization of these processes during martensite ageing

Synthesis and morphological modification of semiconducting Mg(Zn)Al(Ga)–LDH/ITO thin films

Energy Technology Data Exchange (ETDEWEB)

Valente, Jaime S., E-mail: jsanchez@imp.mx [Instituto Mexicano del Petróleo, Eje Central # 152, 07730 México D.F. (Mexico); López-Salinas, Esteban [Instituto Mexicano del Petróleo, Eje Central # 152, 07730 México D.F. (Mexico); Prince, Julia [Universidad Anáhuac México Norte, Av. Universidad Anáhuac # 46, Huixquilucan, Edo. de México 52786 (Mexico); González, Ignacio; Acevedo-Peña, Prospero [Universidad Autónoma Metropolitana-Iztapalapa, Departamento de Química, Apdo. Postal 55-534, 09340 México D.F. (Mexico); Ángel, Paz del [Instituto Mexicano del Petróleo, Eje Central # 152, 07730 México D.F. (Mexico)

2014-09-15

Layered double hydroxide (LDH) thin films with different chemical compositions (MgZnAl, MgZnGa, MgGaAl) and varying thicknesses were easily prepared by sol–gel method followed by dip-coating. Films were chemically uniform, transparent and well adhered to a conductive indium tin oxide (ITO) substrate. Structure, chemical composition and morphology of the thin films were characterized by XRD-GADDS, SEM-EDS and AFM. Additionally, the semiconducting properties of all the prepared films were studied through the Mott–Schottky relationship; such properties were closely related to the chemical compositions of the film. The films were characterized after electrochemical treatment and important modifications regarding surface morphology, particle and crystal sizes were observed. An in-depth study was conducted in order to investigate the effect of several different electrochemical treatments on the morphology, particle size distribution and crystal size of LDH thin films. Upon electrochemical treatment, the films' surface became smooth and the particles forming the films were transformed from flaky open LDH platelets to uniformly distributed close-packed LDH nanoparticles. - Highlights: • Semiconducting Mg(Zn)Al(Ga)–LDH/ITO thin films prepared by sol–gel. • LDH thin films show a turbostratic morphology made up of porous flakes. • Electrochemical treatments change the flaky structure into a nanoparticle array.

Catalysis over zinc-incorporated berlinite (ZnAlPO4 of the methoxycarbonylation of 1,6-hexanediamine with dimethyl carbonate to form dimethylhexane-1,6-dicarbamate

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Sun Da-Lei

2007-11-01

Full Text Available Abstract Background The alkoxycarbonylation of diamines with dialkyl carbonates presents promising route for the synthesis of dicarbamates, one that is potentially 'greener' owing to the lack of a reliance on phosgene. While a few homogeneous catalysts have been reported, no heterogeneous catalyst could be found in the literature for use in the synthesis of dicarbamates from diamines and dialkyl carbonates. Because heterogeneous catalysts are more manageable than homogeneous catalysts as regards separation and recycling, in our study, we hydrothermally synthesized and used pure berlinite (AlPO4 and zinc-incorporated berlinite (ZnAlPO4 as heterogeneous catalysts in the production of dimethylhexane-1,6-dicarbamate from 1,6-hexanediamine (HDA and dimethyl carbonate (DMC. The catalysts were characterized by means of XRD, FT-IR and XPS. Various influencing factors, such as the HDA/DMC molar ratio, reaction temperature, reaction time, and ZnAlPO4/HDA ratio, were investigated systematically. Results The XRD characterization identified a berlinite structure associated with both the AlPO4 and ZnAlPO4 catalysts. The FT-IR result confirmed the incorporation of zinc into the berlinite framework for ZnAlPO4. The XPS measurement revealed that the zinc ions in the ZnAlPO4 structure possessed a higher binding energy than those in ZnO, and as a result, a greater electron-attracting ability. It was found that ZnAlPO4 catalyzed the formation of dimethylhexane-1,6-dicarbamate from the methoxycarbonylation of HDA with DMC, while no activity was detected on using AlPO4. Under optimum reaction conditions (i.e. a DMC/HDA molar ratio of 8:1, reaction temperature of 349 K, reaction time of 8 h, and ZnAlPO4/HDA ratio of 5 (mg/mmol, a yield of up to 92.5% of dimethylhexane-1,6-dicarbamate (with almost 100% conversion of HDA was obtained. Based on these results, a possible mechanism for the methoxycarbonylation over ZnAlPO4 was also proposed. Conclusion As a heterogeneous

Preparation and characterisation of Al-doped Zn O thin films

International Nuclear Information System (INIS)

Saad, M.; Kassis, A.; Nounou, F.

2010-12-01

Al-doped Zn O thin films were prepared using RF magnetron sputtering under several preparation conditions (deposition pressure, RF power, substrate temperature). The films were optically and electrically characterized by measuring their transmission and resistance. Furthermore, x-ray diffraction spectroscopy was used in order to study the structural properties of these films. As a result of this study, the preparation conditions suitable for the highly conductive part of the window layer in solar cells were determined. (author)

Nanoscale formation of new solid-state compounds by topochemical effects: The interfacial reactions ZnO with Al2O3 as a model system

International Nuclear Information System (INIS)

Pin, Sonia; Ghigna, Paolo; Spinolo, Giorgio; Quartarone, Eliana; Mustarelli, Piercarlo; D'Acapito, Francesco; Migliori, Andrea; Calestani, Gianluca

2009-01-01

The chemical reactivity of thin layers (ca. 10 nm thick) of ZnO deposited onto differently oriented Al 2 O 3 single crystals has been investigated by means of atomic force microscopy inspections and X-ray absorption spectroscopy at the Zn-K edge. The (0001) ZnO -parallel (112-bar0) sapphire interface yields the ZnAl 2 O 4 spinel and a quite stable film morphology. Instead, the (112-bar0) ZnO -parallel (11-bar02) sapphire and (0001) ZnO -parallel (0001) sapphire interfaces give origin to a new compound (or, possibly, even two new compounds), whose chemical nature is most likely that of a ZnO/Al 2 O 3 phase, with still unknown composition and crystal structure. In addition, in the last two cases, films collapse into prismatic twins of ca. 1 μm in dimension. These experimental findings demonstrate that in a solid-state reaction, the topotactical relationships between the reacting solids are of crucial importance not only in determining the kinetic and mechanisms of the process in its early stages, but even the chemical nature of the product. - Graphical abstract: EXAFS Fourier transforms and morphology of different reactive interfaces between ZnO and Al 2 O 3 .

FT-Raman and FT-IR spectroscopy of synthetic Mg/Zn/Al-hydrotalcites

International Nuclear Information System (INIS)

Leishman, N.; Kloprogge, J.T.; Fry, R.; Frost, R.L.

1998-01-01

Full text: Hydrotalcites, also known as layered double hydroxides, are less well known and more diffuse in nature than cationic clays. They can be visualised as positively charged hydroxide layers comparable to brucite in which a part of the Mg 2+ is substituted by a trivalent metal like Al 3+ or Fe 3+ separated by charge compensating mostly hydrated interlayer anions. In synthetic hydrotalcites a broad range of compositions are possible of the type [M 2+ 1-x M 3+ x (OH) 2 ][A n- ] x/n -yH 2 O, where M 2+ and M 3+ are the di- and trivalent cations in the octahedral positions within the hydroxide layers with x between 0.17 and 0.33. A n- is an exchangeable interlayer anion. The hydrotalcites with Mg/Zn/Al atomic ratios of 6/0/2, 4/2/2, 2/4/2 and 0/6/2 were synthesised by the slow simultaneous addition of a mixed aluminum-magnesium-zinc nitrate solution and a NaOH solution under vigorous stirring buffering the pH at ± 10. The products were washed to eliminate excess salt and dried at 60 deg C. The nature of the resulting material was checked by XRD and TEM. Both proved the materials to exist of only crystalline hydrotalcite except for the Zn 6 Al 2 (OH) 16 CO 3 .nH 2 O, which contained some unidentified products. The infrared and Raman spectra of synthetic hydrotalcites with different Mg/Zn ratios reveal complicated spectra. Based on the differences in the spectra between the various hydrotalcites and comparison to the comparable hydroxides and hydroxycarbonates a much more detailed band assignment can be made than has been published before

Three series of quaternary rare-earth transition-metal pnictides with CaAl{sub 2}Si{sub 2}-type structures: RECuZnAs{sub 2}, REAgZnP{sub 2}, and REAgZnAs{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Stoyko, Stanislav S.; Ramachandran, Krishna K.; Blanchard, Peter E.R. [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada); Rosmus, Kimberly A.; Aitken, Jennifer A. [Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282 (United States); Mar, Arthur, E-mail: arthur.mar@ualberta.ca [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada)

2014-05-01

Three series of quaternary rare-earth transition-metal pnictides REMM′Pn{sub 2} (M=Cu, Ag; M′=Zn; Pn=P, As) have been prepared by reaction of the elements at 800 °C, with crystal growth promoted through the addition of iodine. The extent of RE substitution is broad in these series: RECuZnAs{sub 2} (RE=Y, La-Nd, Sm, Gd–Lu), REAgZnP{sub 2} (RE=La–Nd, Sm, Gd–Dy), and REAgZnAs{sub 2} (RE=La-Nd, Sm, Gd-Dy). Powder and single-crystal X-ray diffraction analysis revealed that they adopt the trigonal CaAl{sub 2}Si{sub 2}-type structure (space group P3{sup ¯}m1, Z=1), in which Cu or Ag atoms are disordered with Zn atoms over the unique tetrahedrally coordinated transition-metal site. Magnetic measurements indicated Curie–Weiss behavior for several members of the RECuZnAs{sub 2} and REAgZnP{sub 2} series. Core-line X-ray photoelectron spectra (XPS) collected on some RECuZnAs{sub 2} members corroborate the charge assignment deduced by the Zintl concept for these compounds, (RE{sup 3+})(M{sup 1+})(Zn{sup 2+})(Pn{sup 3−}){sub 2}. Optical diffuse reflectance spectra and valence band XPS spectra established that these compounds are small band-gap semiconductors (up to ∼0.8 eV in REAgZnP{sub 2}) or semimetals (RECuZnAs{sub 2}). Band structure calculations also support this electronic structure and indicate that the band gap can be narrowed through appropriate chemical substitution (RE=smaller atoms, M=Cu, and Pn=As). - Graphical abstract: Cu or Ag atoms are disordered with Zn atoms over the tetrahedral site within relatively rigid [M{sub 2}Pn{sub 2}] slabs in three series of quaternary pnictides adopting the CaAl{sub 2}Si{sub 2}-type structure. - Highlights: • Three series (comprising 25 compounds) of pnictides REMM'Pn{sub 2} were prepared. • Cu or Ag atoms are disordered with Zn atoms within relatively rigid [M{sub 2}Pn{sub 2}] slabs. • They are semimetals or small band-gap semiconductors. • RECuZnAs{sub 2} and REAgZnP{sub 2} are generally

Hydroxyapatite coatings containing Zn and Si on Ti-6Al-4Valloy by plasma electrolytic oxidation

Science.gov (United States)

Hwang, In-Jo; Choe, Han-Cheol

2018-02-01

In this study, hydroxyapatite coatings containing Zn and Si on Ti-6Al-4Valloy by plasma electrolytic oxidation were researched using various experimental instruments. The pore size is depended on the electrolyte concentration and the particle size and number of pore increase on surface part and pore part. In the case of Zn/Si sample, pore size was larger than that of Zn samples. The maximum size of pores decreased and minimum size of pores increased up to 10Zn/Si and Zn and Si affect the formation of pore shapes. As Zn ion concentration increases, the size of the particle tends to increase, the number of particles on the surface part is reduced, whereas the size of the particles and the number of particles on pore part increased. Zn is mainly detected at pore part, and Si is mainly detected at surface part. The crystallite size of anatase increased as the Zn ion concentration, whereas, in the case of Si ion added, crystallite size of anatase decreased.

Synthesis, Characterization, and In Vitro Drug Delivery Capabilities of (Zn, Al-Based Layered Double Hydroxide Nanoparticles

Directory of Open Access Journals (Sweden)

Vinay J. Nagaraj

2015-01-01

Full Text Available There is an urgent need for the development of alternative strategies for effective drug delivery to improve the outcome of patients suffering from deadly diseases such as cancer. Nanoparticles, in particular layered double hydroxide (LDH nanoparticles, have great potential as nanocarriers of chemotherapeutic molecules. In this study, we synthesized (Zn, Al-LDH nanoparticles and report their enhanced pH-dependent stability in comparison to the commonly used (Mg, Al-LDH nanoparticles. Fluorescein isothiocyanate (FITC and valproate (VP were intercalated into (Zn, Al-LDH nanoparticles to study cellular uptake, biocompatibility, and drug delivery capabilities using cultured pancreatic adenocarcinoma BxPC3 cells. Fluorescence measurements indicated that FITC-intercalated LDH nanoparticles showed a greater degree of energy-dependent uptake rather than passive uptake by BxPC3 cells, especially at high concentrations of nanoparticles. Tetrazolium-based colorimetric assays indicated that BxPC3 cells treated with VP-intercalated LDH nanoparticles showed a significant reduction in cell viability along with about 30-fold reduction in IC50 compared to the drug alone. In contrast, the non-drug-intercalated LDH nanoparticles did not affect the cell viability indicating very low innate cytotoxicity. Our research indicates that the superior properties of (Zn, Al-LDH nanoparticles make them ideal candidates for further development as in vivo chemotherapy drug delivery agents.

RF and microwave noise suppression in a transmission line using Fe-Si-Al/Ni-Zn magnetic composite films

International Nuclear Information System (INIS)

Lee, J. W.; Hong, Y. K.; Kim, K.; Joo, J.; Yoon, Y. W.; Kim, S. W.; Kim, Y. B.; Kim, K. Y.

2006-01-01

Radio-frequency (RF) and microwave noise suppression by using magnetic composite films on a microstrip line (MSL) was studied in the frequency range from 50 MHz to 13.5 GHz. The MSL was composed of a Cu transmission line, dielectric materials, and a Cu substrate. The Fe-Si-Al/Ni-Zn magnetic composite films were placed on the MSL, and the reflection and the transmission characteristics were investigated. We observed that RF and microwave noise suppression caused by the Fe-Si-Al/Ni-Zn magnetic composite films varied with the concentration ratio of the sendust (Fe-Si-Al) and the Ni-Zn ferrite. The frequency dependence of the power loss due to the composite films on the MSL was measured and the power loss increased at higher frequencies with increasing concentration of the sendust in the composites. The electromagnetic interference shielding efficiencies of the magnetic composite films in the far-field region are also discussed.

Corrosion behaviour of powder metallurgical and cast Al-Zn-Mg base alloys

International Nuclear Information System (INIS)

Sameljuk, A.V.; Neikov, O.D.; Krajnikov, A.V.; Milman, Yu.V.; Thompson, G.E.

2004-01-01

The behaviour of Al-Zn-Mg base alloys produced by powder metallurgy and casting has been studied using potentiodynamic polarisation in 0.3% and 3% NaCl solutions. The influence of alloy production route on microstructure has been examined by scanning electron microscopy, Auger electron spectroscopy and secondary ion mass spectrometry. An improvement in performance of powder metallurgy (PM) materials, compared with the cast alloy, was evident in solutions of low chloride concentration; less striking differences were revealed in high chloride concentration. Both powder metallurgy and cast alloys show two main types of precipitates, which were identified as Zn-Mg and Zr-Sc base intermetallic phases. The microstructure of the PM alloys is refined compared with the cast material, which assists understanding of the corrosion performance. The corrosion process commences with dissolution of the Zn-Mg base phases, with the relatively coarse phases present in the cast alloy showing ready development of corrosion

Effect of Aluminum Doping on the Nanocrystalline ZnS:Al3+ Films Fabricated on Heavily-Doped p-type Si(100) Substrates by Chemical Bath Deposition Method

Science.gov (United States)

Zhu, He-Jie; Liang, Yan; Gao, Xiao-Yong; Guo, Rui-Fang; Ji, Qiang-Min

2015-06-01

Intrinsic ZnS and aluminum-doped nanocrystalline ZnS (ZnS:Al3+) films with zinc-blende structure were fabricated on heavily-doped p-type Si(100) substrates by chemical bath deposition method. Influence of aluminum doping on the microstructure, and photoluminescent and electrical properties of the films, were intensively investigated. The average crystallite size of the films varying in the range of about 9.0 ˜ 35.0 nm initially increases and then decreases with aluminum doping contents, indicating that the crystallization of the films are initially enhanced and then weakened. The incorporation of Al3+ was confirmed from energy dispersive spectrometry and the induced microstrain in the films. Strong and stable visible emission band resulting from the defect-related light emission were observed for the intrinsic ZnS and ZnS:Al3+ films at room temperature. The photoluminescence related to the aluminum can annihilate due to the self-absorption of ZnS:Al3+ when the Al3+ content surpasses certain value. The variation of the resistivity of the films that initially reduces and then increases is mainly caused by the partial substitute for Zn2+ by Al3+ as well as the enhanced crystallization, and by the enhanced crystal boundary scattering, respectively.

TiN/Al2O3/ZnO gate stack engineering for top-gate thin film transistors by combination of post oxidation and annealing

Science.gov (United States)

Kato, Kimihiko; Matsui, Hiroaki; Tabata, Hitoshi; Takenaka, Mitsuru; Takagi, Shinichi

2018-04-01

Control of fabrication processes for a gate stack structure with a ZnO thin channel layer and an Al2O3 gate insulator has been examined for enhancing the performance of a top-gate ZnO thin film transistor (TFT). The Al2O3/ZnO interface and the ZnO layer are defective just after the Al2O3 layer formation by atomic layer deposition. Post treatments such as plasma oxidation, annealing after the Al2O3 deposition, and gate metal formation (PMA) are promising to improve the interfacial and channel layer qualities drastically. Post-plasma oxidation effectively reduces the interfacial defect density and eliminates Fermi level pinning at the Al2O3/ZnO interface, which is essential for improving the cut-off of the drain current of TFTs. A thermal effect of post-Al2O3 deposition annealing at 350 °C can improve the crystalline quality of the ZnO layer, enhancing the mobility. On the other hand, impacts of post-Al2O3 deposition annealing and PMA need to be optimized because the annealing can also accompany the increase in the shallow-level defect density and the resulting electron concentration, in addition to the reduction in the deep-level defect density. The development of the interfacial control technique has realized the excellent TFT performance with a large ON/OFF ratio, steep subthreshold characteristics, and high field-effect mobility.

ETUDE DILATOMÉTRIQUE ET CALORIMÉTRIQUE DES ALLIAGES AL-5.8%MG-2.7%ZN ET AL-6.2%ZN-2.5%MG-1.7%CU

Directory of Open Access Journals (Sweden)

M Benabdoun

2010-06-01

Full Text Available Cet article présente une étude sur la détermination du coefficient linéaire de dilatation thermique et de la capacité calorifique, dans l’intervalle de température [25-400°C] de deux alliages d’aluminium, Al-Zn-Mg et Al-Zn-Mg-Cu dans trois différents états structuraux. Les principaux résultats obtenus dans ce travail montrent que la cinétique des phénomènes liés à la précipitation de la phase η ', dans les deux alliages, est accélérée dans le cas des échantillons ayant subi un traitement thermique d’homogénéisation (H et d’homogénéisation +déformation (H+D, et que le domaine de température correspondant à cette transformation de phase est décalé vers des températures plus basses que celles enregistrées dans le cas des échantillons restés à l’état brut (B. Cette étude montre aussi que le cuivre stabilise les zones de Guignier et Preston(G.P à des températures plus hautes.

Experiment and prediction on thermal conductivity of Al2O3/ZnO ...

Indian Academy of Sciences (India)

Administrator

Experiment and prediction on thermal conductivity of Al2O3/ZnO nano thin film interface structure. PING YANG*, LIQIANG ZHANG, HAIYING YANG†, DONGJING LIU and XIALONG LI. Laboratory of Advanced Manufacturing and Reliability for MEMS/NEMS/OEDS,. School of Mechanical Engineering, Jiangsu University, ...

Influence of heat treatment on corrosion behaviour of Al-Zn-Mg-Cu-Zr-Sc alloy

Energy Technology Data Exchange (ETDEWEB)

Xiao, Y.P.; Liu, X.Y.; He, Y.B. [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Pan, Q.L. [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Nonferrous Materials Science and Engineering, Ministry of Education, Changsha 410083 (China); Li, W.B. [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); School of Civil Engineering, Hunan City University, Yiyang 413000 (China)

2012-05-15

Corrosion behaviour of different tempers (namely NA, UA, PA and OA) of Al-Zn-Mg-Cu-Zr-Sc alloy was studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), optical microscopy (OM) and transmission electron microscopy (TEM). Over aged (OA) can decrease the susceptibility to exfoliation due to the discontinuous distribution of the {eta} precipitates at the grain boundaries, cause a negative shift of the corrosion potential (E{sub corr}), and lead to the prolonging of the time of the appearance of two time constants in impedance diagrams. In addition, Al-Zn-Mg-Cu-Zr-Sc alloy with over aged treatment has an enhanced resistance to exfoliation corrosion. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Influence of semiconductor surface preparation on photoelectric properties of Al-Zn{sub 3}P{sub 2} contacts

Energy Technology Data Exchange (ETDEWEB)

Mirowska, Nella [Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland)]. E-mail: nella.mirowska@pwr.wroc.pl; Misiewicz, Jan [Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland)

2006-06-15

The Schottky barriers formed by Al on Zn{sub 3}P{sub 2} p-type crystals have been studied. Three types of crystals (monocrystal, large-grain crystal and polycrystal) were used for device fabrication. The samples were separated in two groups according to the type of structure and the methods of surface preparation. The samples from the first group were different in structure (monocrystal, large-grain crystal and polycrystals) but prepared in the same way. Three polycrystals with differently prepared surfaces were collected in the second group. Two samples from this group were also annealed in open air at 523 K for 24 h. Measurements of photovoltaic effect at room temperature were carried out to test the impact of surface preparation on photoelectric properties of Al-Zn{sub 3}P{sub 2} contacts. Substantial differences in shape and intensity of PV signal were observed depending on whether the surface of semiconductor was mechanically polished, chemically etched or/and heat treated. The height of potential barrier, {phi} {sub B}, and optical transitions in semiconductor were determined. The value of {phi} {sub B} changed from 0.747 to 0.767 eV for unheated samples and from 0.724 to 0.755 eV for the heated ones. The quality of semiconductor surface seems to have an essential influence on spectral characteristics of Al-Zn{sub 3}P{sub 2} junctions, especially in the case of polycrystals. It appeared that thorough preliminary mechanical polishing of crystals surface provides quite good photoelectric properties of Al-Zn{sub 3}P{sub 2} junctions.

Luminescence of Cr{sup 3+} ions in ZnAl{sub 2}O{sub 4} and MgAl{sub 2}O{sub 4} spinels: correlation between experimental spectroscopic studies and crystal field calculations

Energy Technology Data Exchange (ETDEWEB)

Brik, M.G., E-mail: mikhail.brik@ut.ee [College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Institute of Physics, University of Tartu, W. Ostwald Str. 1, Tartu 50411 (Estonia); Institute of Physics, Jan Dlugosz University, Al. Armii Krajowej 13/15, Czestochowa PL-42200 (Poland); Papan, J.; Jovanović, D.J. [University of Belgrade, Vinča Institute of Nuclear Sciences, P.O. Box 522, Belgrade 11001 (Serbia); Dramićanin, M.D., E-mail: dramican@vinca.rs [University of Belgrade, Vinča Institute of Nuclear Sciences, P.O. Box 522, Belgrade 11001 (Serbia)

2016-09-15

Details of preparation, spectroscopic and structural studies along with crystal field calculations for two Cr{sup 3+} doped spinels MgAl{sub 2}O{sub 4} and ZnAl{sub 2}O{sub 4} are given in the present paper. Both compounds show efficient red emission at about 685 nm, which is due to the {sup 2}E{sub g} → {sup 4}A{sub 2g} spin-forbidden transition of Cr{sup 3+} ions located at the sites with D{sub 3d} local symmetry. Analysis of structure of the CrO{sub 6} clusters was performed; comparison of the crystal field effects in both compounds revealed that the low-symmetry splitting of the orbital triplet states is more pronounced in ZnAl{sub 2}O{sub 4}. Both compounds show potential for applications as red-emitting phosphors. - Highlights: • Cr{sup 3+}-doped MgAl{sub 2}O{sub 4} and ZnAl{sub 2}O{sub 4} spinels were synthesized. • Excitation/emission spectra were recorded and analyzed. • Symmetry properties of the Cr-sites were analyzed. • Cr{sup 3+} energy levels in trigonal crystal field were calculated. • Cr{sup 3+}-doped MgAl{sub 2}O{sub 4} and ZnAl{sub 2}O{sub 4} spinels can be used as red phosphors.

Work hardening characteristics in Al base alloys with 12.6 and 45 wt.% Zn

International Nuclear Information System (INIS)

Abd El-Salam, F.; Mostafa, M.M.; Wahab, L.A.; Mostafa, M.T.; Abd El-Aziz, Sh.M.

2008-01-01

The stress-strain curves were obtained for Al-Zn alloys of 12.6 wt.% Zn (alloy I) and 45 wt.% Zn (alloy II) with elements of purity (99.99). The monotonic shift of these curves towards lower flow stress and higher ductility was interrupted at the transformation temperatures 483 K (alloy I) and both 543, 603 K (alloy II). By increasing deformation temperature, Young's modulus, Y, yield and fracture stresses, σ y and σ f , respectively, fracture time, t f , the coefficient of parabolic work hardening, χ, decreased while fracture strain, ε f , and dislocation slip distance, L, increased. From the obtained X-rays diffraction patterns the lattice strain, ε, crystallite size, η, and dislocation density, ρ, were obtained at different deformation temperatures around transformation

Transparent and flexible heaters based on Al:ZnO degenerate semiconductor

Science.gov (United States)

Roul, Monee K.; Obasogie, Brandon; Kogo, Gilbert; Skuza, J. R.; Mundle, R. M.; Pradhan, A. K.

2017-10-01

We report on high performance transparent Al:ZnO (AZO) thin film heaters on flexible polymer (polyethylene terephthalate) and glass substrates which demonstrate low sheet resistivity. AZO thin films were grown by radio-frequency magnetron sputtering at low Ts (below 200 °C) on flexible, transparent polyethylene terephthalate substrates that show stable and reproducible results by applying low (pain/injury therapy smart windows, automobile window defrosters, and low-cost power electronics.

Wetting and premelting of triple junctions and grain boundaries in the Al-Zn alloys

International Nuclear Information System (INIS)

Straumal, B.; Kogtenkova, O.; Protasova, S.; Mazilkin, A.; Zieba, P.; Czeppe, T.; Wojewoda-Budka, J.; Faryna, M.

2008-01-01

Phase transitions in grain boundaries (GBs) and GB triple junctions (TJs) can change drastically the properties of polycrystals. The GB and TJ wetting phase transition can occur in the two-phase area of the bulk phase diagram where the liquid and solid phases are in equilibrium. The GB and TJ wetting tie-lines can continue in one-phase area of the bulk phase diagram as a GB or TJ solidus line. This line represents the GB or TJ premelting phase transition. The structure and composition of grain boundaries and GB triple junctions were studied by high-resolution electron microscopy and analytical transmission electron microscopy in the Al-5 at.% Zn polycrystals and by differential scanning calorimetry (DSC) in the Al-7.5 at.% Zn polycrystals. Between bulk solidus and GB or TJ solidus the metastable Zn-rich β m -phase was observed in the GB triple junctions of quenched samples. This phase appears neither in the samples annealed above the bulk solidus nor in those annealed below the GB solidus. Zn-content in this β m -phase corresponds to that of bulk liquidus. This is a structural indication that if the melt wets the GBs or TJs, the GB (or TJ) solidus line appears in the bulk phase diagram, and the liquid-like phase exists in GBs and TJs between bulk solidus and GB (or TJ) solidus lines. The structural observation of this phase is also supported by our data obtained by means of DSC

Acetyl salicylic acid–ZnAl layered double hydroxide functional nanohybrid for skin care application

CSIR Research Space (South Africa)

Mosangi, Damodar

2016-10-01

Full Text Available In this study, a pharmaceutically active ingredient, acetyl salicylic acid (ASA), was intercalated into ZnAl layered double hydroxide (LDH). The LDH–ASA nanohybrid material was characterized by XRD, FTIR, SEM, ICP-MS, TEM and TGA. Successful...

Evolution of voids in Al+-implanted ZnO probed by a slow positron beam

International Nuclear Information System (INIS)

Chen, Z.Q.; Maekawa, M.; Yamamoto, S.; Kawasuso, A.; Yuan, X.L.; Sekiguchi, T.; Suzuki, R.; Ohdaira, T.

2004-01-01

Undoped ZnO single crystals were implanted with aluminum ions up to a dose of 10 15 Al + /cm 2 . Vacancy defects in the implanted layers were detected using positron lifetime and Doppler broadening measurements with slow positron beams. It shows that vacancy clusters, which are close to the size of V 8 , are generated by implantation. Postimplantation annealing shows that the Doppler broadening S parameter increases in the temperature range from 200 deg. C to 600 deg. C suggesting further agglomeration of vacancy clusters to voids. Detailed analyses of Doppler broadening spectra show formation of positronium after 600 deg. C annealing of the implanted samples with doses higher than 10 14 Al + /cm 2 . Positron lifetime measurements further suggest that the void diameter is about 0.8 nm. The voids disappear and the vacancy concentration reaches the detection limit after annealing at 600-900 deg. C. Hall measurement shows that the implanted Al + ions are fully activated with improved carrier mobility after final annealing. Cathodoluminescence measurements show that the ultraviolet luminescence is much stronger than the unimplanted state. These findings also suggest that the electrical and optical properties of ZnO become much better by Al + implantation and subsequent annealing

Effect of Al and Mg Contents on Wettability and Reactivity of Molten Zn-Al-Mg Alloys on Steel Sheets Covered with MnO and SiO2 Layers

Science.gov (United States)

Huh, Joo-Youl; Hwang, Min-Je; Shim, Seung-Woo; Kim, Tae-Chul; Kim, Jong-Sang

2018-05-01

The reactive wetting behaviors of molten Zn-Al-Mg alloys on MnO- and amorphous (a-) SiO2-covered steel sheets were investigated by the sessile drop method, as a function of the Al and Mg contents in the alloys. The sessile drop tests were carried out at 460 °C and the variation in the contact angles (θc) of alloys containing 0.2-2.5 wt% Al and 0-3.0 wt% Mg was monitored for 20 s. For all the alloys, the MnO-covered steel substrate exhibited reactive wetting whereas the a-SiO2-covered steel exhibited nonreactive, nonwetting (θc > 90°) behavior. The MnO layer was rapidly removed by Al and Mg contained in the alloys. The wetting of the MnO-covered steel sheet significantly improved upon increasing the Mg content but decreased upon increasing the Al content, indicating that the surface tension of the alloy droplet is the main factor controlling its wettability. Although the reactions of Al and Mg in molten alloys with the a-SiO2 layer were found to be sluggish, the wettability of Zn-Al-Mg alloys on the a-SiO2 layer improved upon increasing the Al and Mg contents. These results suggest that the wetting of advanced high-strength steel sheets, the surface oxide layer of which consists of a mixture of MnO and SiO2, with Zn-Al-Mg alloys could be most effectively improved by increasing the Mg content of the alloys.

Al and Fe co-doped transparent conducting ZnO thin film for mediator-less biosensing application

Directory of Open Access Journals (Sweden)

Shibu Saha

2011-12-01

Full Text Available Highly c-axis oriented Al and Fe co-doped ZnO (ZAF thin film is prepared by pulsed laser deposition. Fe introduces redox centre along with shallow donor level while Al doping enhances conductivity of ZnO, thus removing the requirement of both mediator and bottom conducting layer in bioelectrode. Model enzyme (glucose oxidase, was immobilized on surface of ZAF matrix. Cyclic voltammetry and photometric assay show that prepared bio-electrode is sensitive to glucose concentration with enhanced response of 0.18 μAmM-1cm-2 and low Km ∼ 2.01 mM. The results illustrate that ZAF is an attractive matrix for realization of miniaturized mediator-less solid state biosensor.

A study of the Al-rich part of the Al-Re alloy system

International Nuclear Information System (INIS)

Balanetskyy, S.; Grushko, B.

2008-01-01

The Al-rich part of the Al-Re phase diagram was reinvestigated by scanning and transmission electron microscopy, powder X-ray diffraction and differential thermal analysis. The earlier reported Al 12 Re, Al 6 Re, and Al 11 Re 4 phases were confirmed. Close to the Al 4 Re composition a high-temperature h-Al 4 Re and a low-temperature l-Al 4 Re phase were found to be formed at slightly different compositions. Both exhibited compositional ranges. A new phase was revealed close to the Al 3 Re composition. The Al 11 Re 4 phase is formed congruently at 1650 deg. C, Al 3 Re peritectically at 1610 deg. C, h-Al 4 Re peritectically at 1410 deg. C, l-Al 4 Re peritectically at ∼1000 deg. C, Al 6 Re peritectically at 813 deg. C and Al 12 Re peritectically at 746 deg. C. Finally, the Al 12 Re-(Al) eutectic is formed at 658 deg. C. The Al 3 Re and h-Al 4 Re are decomposed by eutectoid reactions at ∼946 and 833 deg., respectively. The structure of the h-Al 4 Re phase has not yet been clarified, but it is distinctly different from the Al 4 W phase suggested earlier. The structure of l-Al 4 Re was confirmed. The Al 3 Re phase was found to have a monoclinic structure with a = 0.5180(4) nm, b = 3.97641(9) nm, c = 0.4955(3) nm and β = 99.55(7) o

Effect of heat treatment and artificial ageing on Al-5Mg-2Zn

CSIR Research Space (South Africa)

Chauke, Levy

2017-10-01

Full Text Available ageing of Al-5Mg-2Zn. The study showed intermetallic phases at the grain boundaries and a melting peak at about 476 °C for the F condition. Solution heat treatment at 440°C for 4 hours dissolved the intermetallic phase thus increasing the melting point...

Synthesis Al complex and investigating effect of doped ZnO nanoparticles in the electrical and optical efficiency of OLEDS

Science.gov (United States)

Shahedi, Zahra; Jafari, Mohammad Reza

2017-01-01

In this study, an organometallic complex based on aluminum ions is synthesized. And it is utilized as fluorescent material in the organic light-emitting diodes (OLEDs). The synthesized complex was characterized using XRD, UV-Vis, FT-IR as well as PL spectroscopy analyses. The energy levels of Al complex were determined by cyclic voltammetry measurements. Then, the effects of ZnO nanoparticles (NPs) of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), PEDOT:PSS, on the electrical and optical performance of the organic light-emitting diodes have been investigated. For this purpose, two samples containing ITO/PEDOT:PSS/PVK/Alq3/PBD/Al with two different concentration and two samples containing ITO/PEDOT:PSS:ZnO/PVK/Alq3/PBD/Al with two different concentration were prepared. Then, hole transport, electron transport and emissive layers were deposited by the spin coating method and the cathode layer (Al) was deposited by the thermal evaporation method. The OLED simulation was also done by constructing the model and choosing appropriate parameters. Then, the experimental data were collected and the results interpreted both qualitatively and quantitatively. The results of the simulations were compared with experimental data of the J-V spectra. Comparing experimental data and simulation results showed that the electrical and optical efficiency of the samples with ZnO NPs is appreciably higher than the samples without ZnO NPs.

APLIKASI PENGOLAHAN POLUTAN ANION KHROM(VI DENGAN MENGGUNAKAN AGEN PENUKAR ION HYDROTALCIT ZN-AI-SO4 (Synthesis of and its Application to Treat Chrom(VI Pollutant Using Hydrotalcite Zn-Al_SO4 as Anion Exchanger

Directory of Open Access Journals (Sweden)

Roto Roto

2009-03-01

Full Text Available ABSTRAK Keberadaan logam khrom di dalam sistem perairan bersifat polutan yang harus ditangani dengan baik, dan untuk khrom (Vl yang sering dijumpai dalam bentuk anion dapat diolah dengan menggunakan mekanisme pertukaran ion. Suatu agen penukar anion telah dibuat berupa senyawa hidrotalsit Zn-Al-SOa melalui proses sintesis, karakterisasi serta dilakukan pula pengujian aplikasinya untuk pengurangan polutant anion khrom (VI dalam bentuk ion dikromat. Sintesis hidrotalsit Zn-Al-SOa dilakukan dengan metode stoikiometri pada pH 8 dan perlakuan hidrotermal. Aplikasi pertukaran dikromat dengan anion sulfat dalam antar lapis hidrotalsit serta uji regenerasi bahan diamati dengan bantuan analisis struktur dan analisis kinetika reaksi pertukaran. Produk pertukaran ion dikarakterisasi dengan XRD, spektrofotometri IR dan spektrometri serapan atom. Rumus kimia hidrotalsit produk diketahui adalah Zn0,74Al0,26(OH1,74(SO40,13.0,52H2O. Anion dikromat dapat menukar sulfat dalam antarlapis hidrotalsit yang ditunjukkan dalam spektra IR dan pola XRD. Kapasitas pertukaran anion untuk dikromat diketahui 216,84 mek/100 g, sedangkan kinetika reaksi pertukaran ion mengikuti orde dua dengan k = 3 x 10-8 ppm-1.detik-1. Hasil menunjukkan Zn-Al-Cr2O7 dapat mudah diregenerasi.    ABSTRACT  Chrom as pollutant in aquatics system usually establishes as crom (VI and should be worked with special treatment and as an example is ion exchanger. Material Zn-Al-SO4 hydrotalcite product have been synthesized and its application as anion exchanger for dichromate have been studied. Synthesis of Zn-Al-SO4 hydrotalcite was carried out by stoichiometric method at pH 8 and hydrothermal treatment. Sulphate in hydrotalcite interlayer was exchanged by dichromate. Kinetics of ion exchange was also investigated. The product of ion exchange was characterized by XRD, IR spectrophotometry and atomic adsorption  spectrometry. The chemical formula of the  hydrotalcite is Zn0.74Al0.26(OH1.74(SO4 0

Fusion and characterization of an alloy Cu-Zn-Al-Ni of nuclear interest; Fusion y caracterizacion de una aleacion Cu-Zn-Al-Ni de interes nuclear

Energy Technology Data Exchange (ETDEWEB)

Santana M, J.S

2003-07-01

The present work is the result of the study of a non ferrous quatenary alloy of Cu-Zn-Al-Ni (Foundry 3), it was chosen of a series of alloys to obtain so much information of its microstructural properties like mechanical, evaluating them and comparing them with the previously obtained ternary alloys of Cu-AI-Ni (Foundry 1) and Cu-Zn-AI (Foundry 2) identified as alloys of memory effect and superalloys. These were carried out starting from the foundry of their pure elements of Cu, Zn, Al, Ni. When physically having the ingot of each alloy, different techniques were used for their characterization. The used techniques were through the metallographic analysis, by scanning electron microscopy (SEM), X-ray dispersive energy spectroscopy (EDS), X-ray diffraction (XRD), mechanical essays and Rockwell hardness. The non ferrous quaternary alloy Cu-Zn-AI-Ni by means of the metallographic analysis didn't show significant differences in their three sections (superficial, longitudinal and transverse) since result an homogeneous alloy at the same that the both ternaries. The grain size of the quaternary alloy is the finest while the ternary alloy of Cu-AI-Ni is the one that obtained the biggest grain size. Through MEB together with the analysis by EDS and the mapping of the elements that constitute each alloy, show that the three foundries were alloyed, moreover the presence of aggregates was also observed in the Foundries 2 and 3. These results by means of the analysis of XRD corroborate that these alloys have more of two elements. Relating the microstructural properties with those mechanical show us that as minor was the grain size, better they were his mechanical properties, in this case that of the quaternary alloy. With regard to the test of Rockwell hardness the Foundry 1 were the softest with the temper treatment, while that the Foundries 2 and 3 were the hardest with this same treatment, being still harder the Foundry 2 but with very little difference, for what great

Co{sup 2+} adsorption in porous oxides Mg O, Al{sub 2}O{sub 3} and Zn O;Adsorcion de Co{sup 2+} en oxidos porosos MgO, Al{sub 2}O{sub 3} y ZnO

Energy Technology Data Exchange (ETDEWEB)

Moreno M, J. E.; Granados C, F. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Bulbulian, S., E-mail: francisco.granados@inin.gob.m [UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

2009-07-01

The porous oxides Mg O, Al{sub 2}O{sub 3} and Zn O were synthesized by the chemical combustion in solution method and characterized be means of scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The adsorption behavior of Co{sup 2+} ions present in aqueous solution were studied on the synthesized materials by means of experiments lots type to ambient temperature. It was found that the cobalt ions removal was of 90% in Mg O, 65% in Zn O and 72% in Al{sub 2}O{sub 3} respectively, indicating that the magnesium oxide is the best material to remove Co{sup 2+} presents in aqueous solution. (Author)

Effect of atomic layer deposited Al2O3:ZnO alloys on thin-film silicon photovoltaic devices

Science.gov (United States)

Abdul Hadi, Sabina; Dushaq, Ghada; Nayfeh, Ammar

2017-12-01

In this work, we present the effects of the Al2O3:ZnO ratio on the optical and electrical properties of aluminum doped ZnO (AZO) layers deposited by atomic layer deposition, along with AZO application as the anti-reflective coating (ARC) layer and in heterojunction configurations. Here, we report complex refractive indices for AZO layers with different numbers of aluminum atomic cycles (ZnO:Al2O3 = 1:0, 39:1, 19:1, and 9:1) and we confirm their validity by fitting models to experimental data. Furthermore, the most conductive layer (ZnO:Al2O3 = 19:1, conductivity ˜4.6 mΩ cm) is used to fabricate AZO/n+/p-Si thin film solar cells and AZO/p-Si heterojunction devices. The impact of the AZO layer on the photovoltaic properties of these devices is studied by different characterization techniques, resulting in the extraction of recombination and energy band parameters related to the AZO layer. Our results confirm that AZO 19:1 can be used as a low cost and effective conductive ARC layer for solar cells. However, AZO/p-Si heterojunctions suffer from an insufficient depletion region width (˜100 nm) and recombination at the interface states, with an estimated potential barrier of ˜0.6-0.62 eV. The work function of AZO (ZnO:Al2O3 = 19:1) is estimated to be in the range between 4.36 and 4.57 eV. These material properties limit the use of AZO as an emitter in Si solar cells. However, the results imply that AZO based heterojunctions could have applications as low-cost photodetectors or photodiodes, operating under relatively low reverse bias.

Controllable synthesis and tunable luminescence of glass ceramic containing Mn2+:ZnAl2O4 and Pr3+:YF3 nano-crystals

International Nuclear Information System (INIS)

Yu, Yunlong; Li, Xiaoyan

2016-01-01

Highlights: • Glass ceramic containing ZnAl 2 O 4 and YF 3 nano-crystals is fabricated. • Mn 2+ and Pr 3+ are selectively incorporated into ZnAl 2 O 4 and YF 3 , respectively. • The luminescence color can be tuned by adjusting the excitation wavelength. - Abstract: Glass ceramic containing spinel ZnAl 2 O 4 :Mn 2+ and orthorhombic YF 3 :Pr 3+ nano-crystals has been successfully prepared by a melt-quenching technique. X-ray diffraction and transmission electron microscopy demonstrated that two nano-phases, i.e. ZnAl 2 O 4 and YF 3 , were homogeneously distributed among the glass matrix. Importantly, the selective incorporation of Pr 3+ ions into the Y 3+ nine-fold coordinated sites of YF 3 and the segregation of Mn 2+ dopants in the Zn 2+ tetrahedral sites of ZnAl 2 O 4 were confirmed based on the excitation/emission spectra and the crystal field calculation. Under blue light excitation, both Pr 3+ and Mn 2+ in the glass ceramic can be simultaneously excited, and emit red and green luminescence, respectively, owing to the suppression of energy transfer between them. The luminescence color of the obtained glass ceramic can be easily tuned by adjusting the excitation wavelength. These results indicate the potential application of the glass ceramic as converting phosphor to generate white-light after coupling with the blue LED chip.

Spatial structure of radio frequency ring-shaped magnetized discharge sputtering plasma using two facing ZnO/Al2O3 cylindrical targets for Al-doped ZnO thin film preparation

Directory of Open Access Journals (Sweden)

Takashi Sumiyama

2017-05-01

Full Text Available Spatial structure of high-density radio frequency ring-shaped magnetized discharge plasma sputtering with two facing ZnO/Al2O3 cylindrical targets mounted in ring-shaped hollow cathode has been measured and Al-doped ZnO (AZO thin film is deposited without substrate heating. The plasma density has a peak at ring-shaped hollow trench near the cathode. The radial profile becomes uniform with increasing the distance from the target cathode. A low ion current flowing to the substrate of 0.19 mA/cm2 is attained. Large area AZO films with a resistivity of 4.1 – 6.7×10-4 Ω cm can be prepared at a substrate room temperature. The transmittance is 84.5 % in a visible region. The surface roughnesses of AZO films are 0.86, 0.68, 0.64, 1.7 nm at radial positions of r = 0, 15, 30, 40 mm, respectively, while diffraction peak of AZO films is 34.26°. The grains exhibit a preferential orientation along (002 axis.

Assessment of retrogression and re-aging treatment on microstructural and mechanical properties of Al-Zn-Mg-Cu P/M alloy

Energy Technology Data Exchange (ETDEWEB)

Naeem, Haider T. [School of Materials Engineering, Universiti Malaysia Perlis, Taman Muhibbah, 02600 Jejawi, Perlis (Malaysia); College of Engineering, Al-Muthanna University, South Baghdad (Iraq); Mohammad, Kahtan S.; Hussin, Kamarudin; Tan, T. Qing; Idris, M. Sobri [School of Materials Engineering, Universiti Malaysia Perlis, Taman Muhibbah, 02600 Jejawi, Perlis (Malaysia)

2015-05-15

In order to understand the importance of the retrogression and re-aging as a heat treatment for improving microstructural and mechanical properties of the Al-Zn-Mg-Cu powder metallurgy alloys, Al-Zn-Mg-Cu-Fe-Cr alloys were fabricated from the elemental powders. Green compacts are compressed under compaction pressure about 370 MPa. The sintering process carried out for the samples of aluminum alloys at temperature was 650°C under argon atmosphere for two hours. The sintered compacts were subjected into homogenizing condition at 470°C for 1.5 hours and then aged at 120°C for 24 hours (T6 temper) after that it carried out the retrogressed at 180°C for 30 min., and then re-aged at 120°C for 24 hours (RRA). Observations microstructures were examined using optical, scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray diffraction. Density and porosity content was conducted for the samples of alloys. The result showing that the highest Vickers hardness exhibited for an Al-Zn-Mg-Cu alloy after underwent the retrogression and reaging treatment. Increasing in hardness was because of the precipitation hardening through precipitate the (Mg Zn) and (Mg{sub 2}Zn{sub 11}) phases during matrix of aluminum-alloy.

Assessment of retrogression and re-aging treatment on microstructural and mechanical properties of Al-Zn-Mg-Cu P/M alloy

International Nuclear Information System (INIS)

Naeem, Haider T.; Mohammad, Kahtan S.; Hussin, Kamarudin; Tan, T. Qing; Idris, M. Sobri

2015-01-01

In order to understand the importance of the retrogression and re-aging as a heat treatment for improving microstructural and mechanical properties of the Al-Zn-Mg-Cu powder metallurgy alloys, Al-Zn-Mg-Cu-Fe-Cr alloys were fabricated from the elemental powders. Green compacts are compressed under compaction pressure about 370 MPa. The sintering process carried out for the samples of aluminum alloys at temperature was 650°C under argon atmosphere for two hours. The sintered compacts were subjected into homogenizing condition at 470°C for 1.5 hours and then aged at 120°C for 24 hours (T6 temper) after that it carried out the retrogressed at 180°C for 30 min., and then re-aged at 120°C for 24 hours (RRA). Observations microstructures were examined using optical, scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray diffraction. Density and porosity content was conducted for the samples of alloys. The result showing that the highest Vickers hardness exhibited for an Al-Zn-Mg-Cu alloy after underwent the retrogression and reaging treatment. Increasing in hardness was because of the precipitation hardening through precipitate the (Mg Zn) and (Mg 2 Zn 11 ) phases during matrix of aluminum-alloy

Low-Waste Recycling of Spent CuO-ZnO-Al2O3 Catalysts

Directory of Open Access Journals (Sweden)

Stanisław Małecki

2018-03-01

Full Text Available CuO-ZnO-Al2O3 catalysts are designed for low-temperature conversion in the process of hydrogen and ammonia synthesis gas production. This paper presents the results of research into the recovery of copper and zinc from spent catalysts using pyrometallurgical and hydrometallurgical methods. Under reducing conditions, at high temperature, having appropriately selected the composition of the slag, more than 66% of the copper can be extracted in metallic form, and about 70% of zinc in the form of ZnO from this material. Hydrometallurgical processing of the catalysts was carried out using two leaching solutions: alkaline and acidic. Almost 62% of the zinc contained in the catalysts was leached to the alkaline solution, and about 98% of the copper was leached to the acidic solution. After the hydrometallurgical treatment of the catalysts, an insoluble residue was also obtained in the form of pure ZnAl2O4. This compound can be reused to produce catalysts, or it can be processed under reducing conditions at high temperature to recover zinc. The recovery of zinc and copper from such a material is consistent with the policy of sustainable development, and helps to reduce the environmental load of stored wastes.

A study of Cu/ZnO/Al2O3 methanol catalysts prepared by flame combustion synthesis

DEFF Research Database (Denmark)

Jensen, Joakim Reimer; Johannessen, Tue; Wedel, Stig

2003-01-01

The flame combustion synthesis of Cu/ZnO/Al2O3 catalysts for the synthesis of methanol from CO, CO2 and H2 is investigated. The oxides are generated in a premixed flame from the acetyl-acetonate vapours of Cu, Zn and Al mixed with the fuel and air prior to combustion. The flame-generated powder...... temperature and quench-cooling of the flame tend to increase the dispersion of the phases and the specific surface area of the particles. Properties of both the ternary composition, the three binary compositions and the pure oxides are discussed. The calculation of simultaneous phase and chemical equilibrium...

The anodic dissolution of zinc and zinc alloys in alkaline solution. II. Al and Zn partial dissolution from 5% Al–Zn coatings

International Nuclear Information System (INIS)

Vu, T.N.; Mokaddem, M.; Volovitch, P.; Ogle, K.

2012-01-01

Graphical abstract: - Abstract: The polarization behavior of a 5 wt% Al–Zn steel coating (Galfan™) has been investigated in alkaline solution using atomic emission spectroelectrochemistry (AESEC). The instantaneous Zn and Al dissolution rates were measured as a function of time during a linear scan and potential step transients. The formation rate of insoluble oxides was determined from the difference between the convoluted total current and the sum of the elemental dissolution currents. It was found that, over a wide potential range, the zinc and aluminum partial currents behaved in a similar way to pure zinc and pure aluminum independently. However, during the period in which zinc was active, aluminum dissolution was inhibited. This is attributed to the inhibitive effect of the first and/or the second states of zinc oxide that are formed during the active potential domain. The third form of zinc oxide, observed at higher potential and responsible for the passivation of zinc dissolution, does not have a measurable effect on the Al dissolution rate.

Effect of solution heat treatment time on a rheocast Al-Zn-Mg-Cu alloy

CSIR Research Space (South Africa)

Mazibuko, NE

2011-06-01

Full Text Available During rheo-high pressure die casting (R-HPDC) of Al-Zn-Mg-Cu alloys a coarse eutectic phase is formed. This eutectic phase is difficult to take into solution because of its size and it would require longer solution heat treatment times...

Effect of Al doping on the magnetic and electrical properties of Zn(Cu)O based diluted magnetic semiconductors

Science.gov (United States)

Chakraborti, D.; Trichy, G.; Narayan, J.; Prater, J. T.; Kumar, D.

2007-12-01

The effect of Al doping on the magnetic properties of Zn(Cu)O based dilute magnetic semiconducting thin films has been systematically investigated. Epitaxial thin films have been deposited onto sapphire c-plane single crystals using pulsed laser deposition technique. X-ray diffraction and high resolution transmission electron microscopy studies show that the Zn(Cu,Al)O films are epitaxially grown onto (0001) sapphire substrates with a 30°/90° rotation in the basal plane. The large lattice misfit of the order of 16% is accommodated by matching integral multiples of lattice and substrate planes. In these large mismatch systems, the resulting films are fully relaxed following deposition of the first complete monolayer of ZnO (consistent with a critical thickness that is less than one monolayer). Magnetic hysteresis measurements indicate that the pure Zn(Cu)O thin films are ferromagnetic at room temperature. Doping with up to 5% Al (n type) does not significantly affect the ferromagnetism even though it results in an increase in carrier densities of more than 3 orders of magnitude, rising from 1×1017 to 1.5×1020 cm-3. However, for Al additions above 5%, a drop in net magnetization is observed. Annealing the films in an oxygen atmosphere at 600 °C also resulted in a dramatic drop in magnetic moment of the samples. These results strongly suggest that carrier induced exchange is not directly responsible for the magnetic properties of these materials. Rather, a defect mediated exchange mechanism needs to be invoked for this system.

Study of Cu-Al-Zn alloys hardness temperature dependence

International Nuclear Information System (INIS)

Kurmanova, D.T.; Skakov, M.K.; Melikhov, V.D.

2001-01-01

In the paper the results of studies for the Cu-Al-Zn ternary alloys hardness temperature dependence are presented. The method of 'hot hardness' has been used during study of the solid state phase transformations and under determination of the hot stability boundaries. Due to the samples brittleness a hardness temperature dependence definition is possible only from 350-400 deg. C. Sensitivity of the 'hot hardness' method is decreasing within high plasticity range, so the measurements have been carried out only up to 700-800 deg. C. It is shown, that the alloys hardness dependence character from temperature is close to exponential one within the certain structure modification existence domain

Microstructure and Mechanical Properties of Al-10Zn-4.5Mg-xCu Turbine Impeller Produced by Investment Casting

Directory of Open Access Journals (Sweden)

Muhammad Syahid

2017-03-01

Full Text Available Aluminium alloy can be applied for a turbine impeller of Organic Rankine Cycle power plant that operates at temperatures below 150 oC. Aluminum turbine impeller can enhance efficiency of turbine due to light weight material. Al alloys was used for impeller due to good mechanical properties. Turbine impeller commonly produced by machining but which is time-consuming and less efficient because of material removal. . It can be replace by Investment casting to produce impeller turbine due to their complex geometry and precision. This study identifies effect Cu content of Al-9Zn-4Mg-xCu on the microstructure and mechanical properties of turbine impeller produce by investment casting. The study also identifies casting defect of turbine impeller. The structures consisted of α-Al, MgZn2, CuMgAl2 and CuAl2. Higher Cu content is the higher hardness value due to CuAl2 phase. Visual examination showed that the turbine impeller was free of macro defects and misruns

Effect of Various Retrogression Regimes on Aging Behavior and Precipitates Characterization of a High Zn-Containing Al-Zn-Mg-Cu Alloy

Science.gov (United States)

Wen, Kai; Xiong, Baiqing; Zhang, Yongan; Li, Zhihui; Li, Xiwu; Huang, Shuhui; Yan, Lizhen; Yan, Hongwei; Liu, Hongwei

2018-03-01

In the present work, the influence of various retrogression treatments on hardness, electrical conductivity and mechanical properties of a high Zn-containing Al-Zn-Mg-Cu alloy is investigated and several retrogression regimes subjected to a same strength level are proposed. The precipitates are qualitatively investigated by means of transmission electron microscopy (TEM) and high-resolution transmission electron microscopy techniques. Based on the matrix precipitate observations, the distributions of precipitate size and nearest inter-precipitate distance are extracted from bright-field TEM images projected along Al orientation with the aid of an imaging analysis and an arithmetic method. The results show that GP zones and η' precipitates are the major precipitates and the precipitate size and its distribution range continuously enlarge with the retrogression regime expands to an extent of high temperature. The nearest inter-precipitate distance ranges obtained are quite the same and the average distance of nearest inter-precipitates show a slight increase. The influence of precipitates on mechanical properties is discussed through the interaction relationship between precipitates and dislocations.

Effect of Various Retrogression Regimes on Aging Behavior and Precipitates Characterization of a High Zn-Containing Al-Zn-Mg-Cu Alloy

Science.gov (United States)

Wen, Kai; Xiong, Baiqing; Zhang, Yongan; Li, Zhihui; Li, Xiwu; Huang, Shuhui; Yan, Lizhen; Yan, Hongwei; Liu, Hongwei

2018-05-01

In the present work, the influence of various retrogression treatments on hardness, electrical conductivity and mechanical properties of a high Zn-containing Al-Zn-Mg-Cu alloy is investigated and several retrogression regimes subjected to a same strength level are proposed. The precipitates are qualitatively investigated by means of transmission electron microscopy (TEM) and high-resolution transmission electron microscopy techniques. Based on the matrix precipitate observations, the distributions of precipitate size and nearest inter-precipitate distance are extracted from bright-field TEM images projected along Al orientation with the aid of an imaging analysis and an arithmetic method. The results show that GP zones and η' precipitates are the major precipitates and the precipitate size and its distribution range continuously enlarge with the retrogression regime expands to an extent of high temperature. The nearest inter-precipitate distance ranges obtained are quite the same and the average distance of nearest inter-precipitates show a slight increase. The influence of precipitates on mechanical properties is discussed through the interaction relationship between precipitates and dislocations.

Effect of the Milling Time of the Precursors on the Physical Properties of Sprayed Aluminum-Doped Zinc Oxide (ZnO:Al Thin Films

Directory of Open Access Journals (Sweden)

María De La Luz Olvera

2012-08-01

Full Text Available Aluminum doped zinc oxide (ZnO:Al thin films were deposited on soda-lime glass substrates by the chemical spray technique. The atomization of the solution was carried out by ultrasonic excitation. Six different starting solutions from both unmilled and milled Zn and Al precursors, dissolved in a mix of methanol and acetic acid, were prepared. The milling process was carried out using a planetary ball mill at a speed of 300 rpm, and different milling times, namely, 15, 25, 35, 45, and 60 min. Molar concentration, [Al]/[Zn] atomic ratio, deposition temperature and time, were kept at constant values; 0.2 M, 3 at.%, 475 °C, and 10 min, respectively. Results show that, under the same deposition conditions, electrical resistivities of ZnO:Al thin films deposited from milled precursors are lower than those obtained for films deposited from unmilled precursors. X-ray diffraction analysis revealed that all films display a polycrystalline structure, fitting well with the hexagonal wurtzite structure. Changes in surface morphology were observed by scanning electron microscopy (SEM as well, since films deposited from unmilled precursors show triangular shaped grains, in contrast to films deposited from 15 and 35 min milled precursors that display thin slices with hexagonal shapes. The use of milled precursors to prepare starting solutions for depositing ZnO:Al thin films by ultrasonic pyrolysis influences their physical properties.

Toxicity of nanoparticulate and bulk ZnO, Al{sub 2}O{sub 3} and TiO{sub 2} to the nematode Caenorhabditis elegans

Energy Technology Data Exchange (ETDEWEB)

Wang Huanhua; Wick, Robert L. [Department of Plant, Soil and Insect Sciences, University of Massachusetts, Stockbridge Hall, Amherst, MA 01003 (United States); Xing Baoshan [Department of Plant, Soil and Insect Sciences, University of Massachusetts, Stockbridge Hall, Amherst, MA 01003 (United States)], E-mail: bx@pssci.umass.edu

2009-04-15

Limited information is available on the environmental behavior and associated potential risk of manufactured oxide nanoparticles (NPs). In this research, toxicity of nanoparticulate and bulk ZnO, Al{sub 2}O{sub 3} and TiO{sub 2} were examined to the nematode Caenorhabditis elegans with Escherichia coli as a food source. Parallel experiments with dissolved metal ions from NPs were also conducted. The 24-h median lethal concentration (LC{sub 50}) and sublethal endpoints were assessed. Both NPs and their bulk counterparts were toxic, inhibiting growth and especially the reproductive capability of the nematode. The 24-h LC{sub 50} for ZnO NPs (2.3 mg L{sup -1}) and bulk ZnO was not significantly different, but significantly different between Al{sub 2}O{sub 3} NPs (82 mg L{sup -1}) and bulk Al{sub 2}O{sub 3} (153 mg L{sup -1}), and between TiO{sub 2} NPs (80 mg L{sup -1}) and bulk TiO{sub 2} (136 mg L{sup -1}). Oxide solubility influenced the toxicity of ZnO and Al{sub 2}O{sub 3} NPs, but nanoparticle-dependent toxicity was indeed observed for the investigated NPs. - ZnO, Al{sub 2}O{sub 3} and TiO{sub 2} nanoparticles are more toxic than their bulk counterparts to the nematode, Caenorhabditis elegans.

Development of ZnO:Al-based transparent contacts deposited at low-temperature by RF-sputtering on InN layers

Energy Technology Data Exchange (ETDEWEB)

Fernandez, S. [Departamento de Energias Renovables, Energia Solar Fotovoltaica, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avda. Complutense 22, 28040 Madrid (Spain); Naranjo, F.B.; Valdueza-Felip, S. [Grupo de Ingenieria Fotonica, Departamento de Electronica, Escuela Politecnica Superior, Universidad de Alcala Campus Universitario, 28871 Alcala de Henares, Madrid (Spain); Abril, O. de [ISOM and Departamento de Fisica Aplicada, Escuela Tecnica Superior de Ingenieros de Telecomunicacion, Universidad Politenica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain)

2012-03-15

Nitride semiconductors (Al,Ga,In)N attain material properties that make them suitable for photovoltaic and optoelectronics devices to be used in hard environments. These properties include an energy gap continuously tuneable within the energy range of the solar spectrum, a high radiation resistance and thermal stability. The developing of efficient devices requires contacts with low resistivity and high transmittance in visible region. ZnO:Al (AZO) emerges as a feasible candidate for transparent contact to nitride semiconductors, taking advantage of its low resistivity, high transparency in visible wavelengths and a very low lattice mismatch with respect to nitride semiconductors. This work presents a study of the applications of AZO films deposited at low-temperature by RF magnetron sputtering as transparent contact for InN layers. The optimization of AZO conditions deposition lead to the obtaining of contacts which shows an ohmic behaviour for the as-deposited layer, regardless the thickness of the ZnO:Al contact layer. Specific contact resistances of 1.6 {omega}.cm{sup 2} were achieved for the contact with 90 nm thick ZnO:Al layer without any post-deposition treatment (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Structural, Morphological, and LPG Sensing Properties of Al-Doped ZnO Thin Film Prepared by SILAR

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Shampa Mondal

2013-01-01

Full Text Available Undoped and aluminum doped zinc oxide (AZO thin films were deposited on glass substrates by successive ion layer adsorption and reaction (SILAR technique from ammonium zincate complex. The thin films are characterized by X-ray diffraction (XRD and scanning electron microscopy (SEM for their structural and morphological studies. Both undoped and Al-doped film show strong preferred c-axis orientation. The texture coefficient (TC of the film along (002 direction increases due to Al incorporation. SEM micrograph shows round shaped particles for pure ZnO. However AZO films show particles with off spherical shape and compact interconnected grains. Sensitivity of the film in presence of 80% LEL (lower explosive limit of LPG increases with temperature and is maximum at 325°C. Significantly high sensitivity of 87% with reasonably fast response was observed for 1% Al-doped ZnO (AZO film in presence of 1.6 vol% LPG at 325°C.