Synthesis and magnetic properties of CuAlO2 from high-energy ball-milled Cu2O Al2O3 mixture (original) (raw)

The Investigation of Effect of Defects on the Structural, Optical, and Magnetic Properties of CuAlO2

Acta Physica Polonica A, 2022

Rapid synthesis of delafossite CuAlO2 was achieved by a solid-state reaction method. The synthesized sample was subjected to phase analysis by X-ray diffraction. The desired crystalline phase was obtained and all peaks in the X-ray diffraction phase investigation were found to belong to the CuAlO2 pattern. Morphological and stoichiometric properties were defined by a scanning electron microscope and insitu attachment of energy dispersive spectroscopy. X-ray photoelectron spectroscopy measurements were done to provide a detailed elemental composition analysis in the parts per thousand ranges. Xray photoelectron spectroscopy measurements revealed that the core level of the 4 electron species Cu 2p, Al 2p, and O 1s exists. The structural defects of CuAlO2 were investigated using the Agilent Cary Eclipse Fluorescence Spectrophotometer. The photoluminescence measurements showed that the near-band emission, cooper vacancy, and oxygen vacancy emission occurred. The nature of optical and magnetic properties of the CuAlO2 sample was defined by Quantum Design Physical Properties Measurement System and correlated with the X-ray photoelectron spectroscopy and photoluminescence results.

Critical Analysis on the Structural and Magnetic Properties of Bulk and Nanocrystalline Cu-Fe-O

Advances in Materials Science and Engineering, 2010

Nanocrystalline and bulk samples of “Fe”-doped CuO were prepared by coprecipitation and ceramic methods. Structural and compositional analyses were performed using X-ray diffraction, SEM, and EDAX. Traces of secondary phases such as CuFe2O4, Fe3O4, andα-Fe2O3having peaks very close to that of the host CuO were identified from the Rietveld profile analysis and the SAED pattern of bulk and nanocrystalline Cu0.98Fe0.02O samples. Vibrating Sample Magnetometer (VSM) measurements show hysteresis at 300 K for all the samples. The ferrimagnetic Neel transition temperature () was found to be around 465°C irrespective of the content of “Fe”, which is close to the value of cubic CuFe2O4. High-pressure X-Ray diffraction studies were performed on 2% “Fe”-doped bulk CuO using synchrotron radiation. From the absence of any strong new peaks at high pressure, it is evident that the secondary phases if present could be less than the level of detection. Cu2O, which is diamagnetic by nature, was also d...

Growth of Delafossite CuCr1−xMxO2 Systems and Their Anisotropic Magnetization

Jurnal Fisika dan Aplikasinya, 2011

The effort to obtain a good crystalline state of delafossite CuCrO2 phase is becoming important along with their potential application and scientific important results. In this paper we report the result of crystal growth and their Magnetic and Electric Capacitance Measurements. We focused on two methods i.e. flux decomposition (FD), and Bi2O3 Flux Growth (FB). The starting materials for FD growth were K2Cr2O7 and CuO taking the advantage of the potassium dichromate's decomposition. In case of FB flux growth, we should prepare the correct molar ratio for CuCrO2 pellet on the Bi2O3 powder in 1 : 6 ratio. It is found that both methods are possible to obtain crystalline phases along with their specific technical processes to be overcomed. We show that FB method resulted flaky shapes while FD method produced rather bulky morphology. The obtained samples were checked by CAD4 single crystal diffractometer for their lattices and MPMS-SQUID magnetometer for their magnetization for different orientation. We check also the electric capacitance at the range of 5 K to 300 K along c lattice direction. It is found that their single Neel temperature (TN) fall around 25 K. A distinct anisotropy of magnetization profiles shown by its crystal directions and planes. On the other hand the out of plane electric capacitance of Mn doped crystal did not show any transition at the range of 5 K to 300 K.

One Pot Synthesis, Surface and Magnetic Properties of Cu2O/Cu and Cu2O/CuO Nanocomposites

Crystals, 2021

A series of copper-based systems containing two different nanocomposites (Cu2O/CuO and Cu2O/Cu) was synthesized by the egg white assisted auto-combustion route. This method was distinguished by the simplicity of its steps, low cost, one-pot synthesis process at low temperature and, short time. The characterization of the as prepared nanocomposites was carried out by using X-ray diffraction (XRD), Fourier-transform infrared (FTIR), Scanning electron microscope (SEM) and transmission electron micrograph (TEM), Energy dispersive spectrometry (EDS) techniques. Surface and magnetic properties of the obtained systems were determined by using N2 adsorption/desorption isotherms at 77 K and the vibrating sample magnetometer (VSM) technique. XRD results confirmed the formation of Cu2O/CuO and Cu2O/Cu nanocomposites with different ratios of well crystalline CuO, Cu2O, and Cu phases. FTIR results of the combusted product displays the presence of both CuO and Cu2O, respectively. SEM/EDS and TEM ...

Sol–gel synthesis and characterization of the delafossite CuAlO2

Journal of Sol-Gel Science and Technology, 2015

Nanocrystalline CuAlO 2 is synthesized by solgel method using ethylene glycol as solvent. The stages of formation are followed by thermal analysis. The X-ray diffraction pattern of the powder heat-treated at 1100°C shows a single phase, indexed in a rhombohedral symmetry (R 3 m). The apparent crystallite size (57 ± 8 nm) is determined from the Williamson-Hall plot. The direct optical transition (=3.69 eV), evaluated from the diffuse reflectance spectrum, is attributed to the charge transfer (O 2-: 2p ? Cu ? : 4s). The oxide is p-type semiconductor, and the conduction occurs predominantly by small polaron hopping between mixed valences Cu 2?/? , due to oxygen insertion in the layered crystal. The photoelectrochemical characterization gives a flat band of 0.20 V SCE and a hole density of 1.13 9 10 18 cm-3. The semicircle centered on the real axis, in the electrochemical impedance spectroscopy (EIS), is due to the absence of constant phase element with a pure capacitive behavior. The straight line at 35°at low frequencies is attributed to the diffusion in the layered structure. Graphical Abstract Temperature dependence of the electrical conductivity for CuAlO 2 synthesized by sol-gel method. Inset: the variable range hopping at low temperatures. The sol-gel method has been successfully employed 10 Hz

Magnetic properties and chemical state of nickel doped Cu FeO 2 delafossite oxide powders prepared by sol-gel method

Materials Today: Proceedings, 2018

Nickel doped CuFeO 2 were synthesized by using sol-gel method and two steps heat annealing. The first annealing was executed at 500ºC in air to transform the dried gels into spinel oxide phases and the second one was done at 800ºC in argon to transform the spinel oxide phase into the delafossite oxide phase. The crystal orientation and the morphology of nanostructure of annealed samples were investigated. Result revealed that CuFe 1-x Ni x O 2 samples are hexagonal delafossite structure and the average grain size is 0.258-0.760 µm. The CuFeO 2 sample exhibited the paramagnetic behavior. The CuFe 1-x Ni x O 2 (x = 0.01-0.05) samples exhibited a weak ferromagnetic behavior and a linear paramagnetic behavior upon hysteresis was observed. The maximum of coercivity, remanence and area of hysteresis loop were 26.06 mT, 1.84x10-4 a.u. and 39.63x10-3 , respectively. In addition, the valence states of delafossite oxide were also characterized. The results suggest that Cu oxidation state of mixture between Cu + and Cu 2+ ions, Fe oxidation state of Fe 3+ as majority ions and Ni oxidation state of Ni 2+ ions.

Magnetic properties of undoped Cu 2 O fine powders with magnetic impurities and/or cation vacancies

Fine powders of micron-and submicron-sized particles of undoped Cu 2 O semiconductor, with three different sizes and morphologies have been synthesized by different chemical processes. These samples include nanospheres 200 nm in diameter, octahedra of size 1 μm, and polyhedra of size 800 nm. They exhibit a wide spectrum of magnetic properties. At low temperature, T = 5 K, the octahedron sample is diamagnetic with the magnetic susceptibility, χ OH =-9.5×10-6 emu.g-1 .Oe-1. The nanosphere is paramagnetic with χ NS = 2.2×10-5 emu.g-1 .Oe-1. The other two polyhedron samples synthesized in different runs by the same process are found to show different magnetic properties. One of them exhibits weak ferromagnetism with T C ~ 455 K and saturation magnetization, M S a

Structural, Morphological and Ferromagnetic Properties of Pure and (Mn, Co) Codoped CuO Nanostructures

Ferromagnetic oxide semiconductor of pure and (Mn, Co) codoped CuO nanocrystals were synthesized by a chemical coprecipitation method. The phase structure , morphology and room temperature ferromagnetism were investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and vibrating sample magnetome-ter (VSM). Results of XRD demonstrated that both the undoped and (Mn, Co) codoped CuO samples have single phase of CuO monoclinic structure and no secondary phases were detected, suggesting the incorporation of Mn and Co dopants in CuO lattice. The FTIR spectra of all samples showed three main absorption bands attributed to stretching vibrations of Cu–O bond. The morphology of the pure CuO was found to change from nanoparticle to nanorod structure after codoping with Mn and Co ions. The diameter and length of the nanorods were nearly 28–60 and 130–550 nm, respectively. The obtained magnetic hysteresis loops at room temperature confirmed the ferromagnetic nature of all the prepared samples, which was enhanced after the incorporation of Mn and Co ions into CuO lattice. The effect of the codoped ions on the structure and ferromagnetism are discussed.

Synthesis and characterization of Cu2+ substituted magnetite

Hyperfine Interactions, 2011

Samples of magnetite, both pure and doped with divalent copper, Fe 3−x Cu x O 4 , with x = 0, 0.05, 0.10 and 0.20 atm.%, were synthesized hydrothermally. The samples were characterized by Atomic Absorption Spectroscopy, Mössbauer Spectroscopy, X-ray diffraction, Scanning Electron Microscopy and SQUID magnetometry. The analyses made by the above techniques showed that as the Cu 2+ concentration increases, a simultaneous reduction in the magnetic and structural parameters takes place, namely: magnetic hyperfine interactions at octahedral sites, particle size and lattice constant. Degradation in the particles morphology as well as a distribution of their size were also observed. Our study points two important effects of Cu 2+ in magnetite, the first one is its incorporation within the structure, replacing Fe 2+ ions and decreasing both the magnetic hyperfine interactions at octahedral sites and the bulk magnetization, the second one is the contraction of the crystalline lattice of magnetite, because incorporation of Cu 2+ within the structure, generation of vacancies or both simultaneous effects.

Metal transition doping effect on the structural and physical properties of delafossite-type oxide CuCrO2

Journal of Alloys and Compounds, 2011

In this paper we reported on the non magnetic substitution effects on the structural, spectroscopic, and magnetic properties of the CuCrO 2 delafossite. The incorporation of M 3+ generates very anisotropic microstrains in the structure beside a magnetic dilution. The temperature dependence of all samples exhibits paramagnetic behavior at high temperature. It is argued that non magnetic-substitution destabilizes the antiferromagnetic order of Cr 3+ ions and modulates the spin configuration leading to a weak ferromagnetism. The coupling between the magnetic order and ferroelectric order is also characterized.