The Influence of CeO2-Doping of Nanosized Cadmium Ferrite on Catalytic Conversion of Ethanol

Background: The role of CeO2-doping (0.75-3 mol%) and calcination temperature on solid-solid interaction between ferric and cadmium oxides yielding cadmium ferrites was examined. Methods and Results: The results exposed that ceria improves the ferrite formation by heating at 600-700ºC via the dissolution of some dopant cation in the lattice of CdO with the subsequent creation of anionic vacancies and/or formation of higher valency cadmium cation (Cd(2+δ)+). SBET of solids calcined at 500oC increased by CeO2-doping, while opposite trend for solids calcined at 600 and 700oC. The magnetic hysteresis loops of all samples showed room-temperature ferromagnetism with different hysteresis loop shapes. Conclusion: Magnetization increased by CeO2-doping that might be due to the enhancement of cadmium ferrite formation. Ethanol conversion increased by increasing CeO2-doping. Dehydrogenation product (acetaldehyde) was mainly the yield of ethanol conversion. The maximum yield of acetaldehyde (92.97%) carried out for solids doped with 3 mol% CeO2.

Download Full-text

Ferroelectric and Magnetic Properties of Hot-Pressed BiFeO3-PVDF Composite Films

ISRN Materials Science ◽

10.5402/2011/142968 ◽

2011 ◽

Vol 2011 ◽

pp. 1-5 ◽

Cited By ~ 10

Author(s):

Annapu V. Reddy ◽

K. C. Sekhar ◽

Navneet Dabra ◽

A. Nautiyal ◽

Jasbir S. Hundal ◽

...

Keyword(s):

Magnetic Properties ◽

Coercive Field ◽

Polyvinylidene Fluoride ◽

Room Temperature ◽

Magnetic Hysteresis ◽

Composite Films ◽

Hysteresis Loops ◽

Liquid Phase Sintering ◽

Magnetic Hysteresis Loops ◽

Ferroelectric Hysteresis

The ferroelectric and magnetic properties of hot-pressed BiFeO3- (BFO) polyvinylidene fluoride (PVDF) composite films have been studied. The BiFeO3 (BFO) ceramics have been synthesized by a rapid liquid phase sintering technique. The X-ray diffraction (XRD) studies revealed that the impure phase observed in pure BFO ceramics was significantly reduced in the composite films. The presence of both ferroelectric and magnetic hysteresis loops confirms the multiferroic nature of the composite films at room temperature. A well-saturated ferroelectric hysteresis loop with a remanent polarization (Pr)∼4.8 μC-cm-2 and coercive field (Ec)∼1.55 kV/cm has been observed in composite thin films at room temperature. The magnetic hysteresis loops were traced at room temperature with SQUID. The remanent magnetization (Mr)∼3.0×10−3 emu/gm and coercive field (Hc)∼0.99 kOe was observed in the composite film. The magnetic polarization of the composite films has found to be enhanced as compared to pure BFO and correlated to reduction in BFO impure peak intensity.

Download Full-text

Structural and Magnetic Properties of the Rapid Cooled Alloys: Fe60Co10Y5+xZr5-xB20 (Where: x = 0 or 2)

Revista de Chimie ◽

10.37358/rc.19.1.6887 ◽

2019 ◽

Vol 70 (1) ◽

pp. 224-227

Author(s):

Marcin Nabialek ◽

Bartlomiej Jez ◽

Kinga Jez ◽

Katarzyna Bloch

Keyword(s):

Room Temperature ◽

Nanocrystalline Material ◽

Magnetic Hysteresis ◽

Hysteresis Loops ◽

Single Step ◽

Magnetic Polarization ◽

X Ray ◽

High Temperature Alloys ◽

Magnetic Hysteresis Loops ◽

Vibration Magnetometer

This article presents the results of tests on high-temperature alloys, produced on the basis of the FeCoB matrix. The nanocrystalline material was produced in a single-step process of rapid cooling of liquid alloy that was injected into a copper mould. Alloy samples were obtained in the form of 10mm x 5mm x 0.5mm tiles. Studies of the structure of the manufactured alloys were undertaken using Bruker X-ray analysis equipment (featuring a CuKa lamp). The magnetic polarization of saturation was measured, as a function of temperature, using a Faraday magnetic balance; the measurements ranged from room temperature up to 850K. Through numerical analysis of the curves, the Curie temperature of the investigated alloys was determined. Using a vibration magnetometer, static magnetic hysteresis loops were measured. The magnetization of saturation of the tested alloys was greater than 1 T, while the coercive field values were 400 and 16600 A/m. The stiffness parameter of the spin wave Dspf was determined.

Download Full-text

Preparation and Properties of Zn1-XCoxO Magnetic Microspheres

Materials Science Forum ◽

10.4028/www.scientific.net/msf.663-665.1081 ◽

2010 ◽

Vol 663-665 ◽

pp. 1081-1084

Author(s):

Zhi Fu Liu ◽

Qing Hong Zhang ◽

Li Yun Chen ◽

Yao Gang Li ◽

Hong Zhi Wang

Keyword(s):

Electron Microscopy ◽

Room Temperature ◽

Magnetic Hysteresis ◽

Hysteresis Loops ◽

Magnetic Microspheres ◽

Diffraction Field ◽

Vibrating Sample Magnetometry ◽

X Ray ◽

Transmission Electron ◽

Magnetic Hysteresis Loops

Zn1-xCoxO magnetic microspheres have been synthesized by a simple solvothermal process. Different Co2+ dopant concentrations have been used as modifier and proved to be efficient at controlling the morphology and magnetic property of Zn1-xCoxO microspheres. The as-synthesized samples are characterized by X-ray powder diffraction, field-emission scanning electron microscopy, transmission electron microscopy, photoluminescence spectrophotometer and vibrating sample magnetometry. Magnetic hysteresis loops reveal the samples exhibit ferromagnetic loops at room temperature. The meta-saturation magnetization value and coercivity of Zn0.8Co0.2O reach 0.09 emu·g-1 and 15.0 Oe.

Download Full-text

Asymmetric Hysteresis Loops in Co Thin Films

Condensed Matter ◽

10.3390/condmat5040071 ◽

2020 ◽

Vol 5 (4) ◽

pp. 71

Author(s):

Andrea Ehrmann ◽

Tomasz Blachowicz

Keyword(s):

Exchange Bias ◽

Kerr Effect ◽

Room Temperature ◽

Magnetic Hysteresis ◽

Hysteresis Loops ◽

Blocking Temperature ◽

Optical Kerr Effect ◽

Thin Film System ◽

Magnetic Hysteresis Loops ◽

Magneto Optical Kerr Effect

Asymmetric magnetic hysteresis loops are usually found in exchange bias (EB) systems, typically after field cooling a system below the Néel temperature of an antiferromagnet exchange coupled to a ferromagnet. Alternatively, asymmetric hysteresis loops may occur due to undetected minor loops or in systems with a rotational anisotropy. Here, we report on an exchange bias thin film system MgO(100)/Co/CoO, examined at room temperature, which is far above the blocking temperature, by the magneto-optical Kerr effect (MOKE). While the longitudinal hysteresis loops partly show steps which are well-known from diverse purely ferromagnetic systems, the transverse hysteresis loops exhibit clear asymmetries, similar to exchange biased systems at low temperatures, and unusual transverse magnetization values at saturation. Since minor loops and a rotational anisotropy can be excluded in this case, this asymmetry can possibly be a residue of the exchange bias coupling at lower temperatures.

Download Full-text

OXIDATION PROCESS OF Fe NANOPARTICLES

Modern Physics Letters B ◽

10.1142/s0217984907013845 ◽

2007 ◽

Vol 21 (18) ◽

pp. 1143-1151 ◽

Cited By ~ 8

Author(s):

K. SIMEONIDIS ◽

S. MOURDIKOUDIS ◽

I. TSIAOUSSIS ◽

N. FRANGIS ◽

M. ANGELAKERIS ◽

...

Keyword(s):

Oxidation Process ◽

Magnetic Hysteresis ◽

Hysteresis Loops ◽

X Ray Diffraction ◽

X Ray ◽

Ft Ir ◽

Magnetic Hysteresis Loops ◽

Conventional Microscopy ◽

Ft Ir Spectroscopy

The natural oxidation process is studied in the case of 15 nm iron nanoparticles produced by the thermal decomposition of Fe(CO) 5. X-ray diffraction spectra of the nanoparticles at different timescales after exposure to air revealed the instant oxidation of iron and the formation of wüstite and magnetite. Wüstite mainly occupies the interior of nanoparticles, as evidenced by microscopy, but is slowly transformed to a spinel structure. The shape, the dispersion and the role of surfactant were investigated by conventional microscopy and Fourier Transformed-Infrared (FT-IR) spectroscopy. Magnetic hysteresis loops confirmed the expected variation of magnetic properties till the steady state.

Download Full-text

Dielectric and magnetic properties in Ta-substituted BiFeO3 ceramics

Journal of Materials Research ◽

10.1557/jmr.2007.0421 ◽

2007 ◽

Vol 22 (12) ◽

pp. 3397-3403 ◽

Cited By ~ 26

Author(s):

Youn-Ki Jun ◽

Sung Bo Lee ◽

Miyoung Kim ◽

Seong-Hyeon Hong ◽

Jae Wook Kim ◽

...

Keyword(s):

Dielectric Constant ◽

Magnetic Properties ◽

Room Temperature ◽

Magnetic Hysteresis ◽

Hysteresis Loops ◽

High Resistivity ◽

Magnetic Dipoles ◽

Low Dielectric ◽

Polycrystalline Ceramics ◽

Magnetic Hysteresis Loops

The dielectric and magnetic properties were investigated in Ta-substituted BiFeO3 polycrystalline ceramics synthesized by a solid-state reaction. The Ta substitution decreased the grain size by two orders of magnitude compared with that of unsubstituted ceramics and increased the electrical resistivity by 6 orders of magnitude. The high resistivity and low dielectric loss allowed the dielectric constant to be determined at room temperature. The magnetic hysteresis loops were observed in the Ta-substituted BiFeO3, and the appearance of ferromagnetism was closely associated with the distortion of the oxygen octahedra by the Ta substitution. The coupling between the electric and magnetic dipoles was examined by determining the changes of the dielectric constant with the external magnetic field.

Download Full-text

Nano PTFE Polymer Films as Organic Insulating Barrier for Tunneling Magneto-Resistive Fe/PTFE/Fe Devices

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.67.13 ◽

2009 ◽

Vol 67 ◽

pp. 13-17

Author(s):

S. Sundar Manoharan ◽

Vimlesh Chandra

Keyword(s):

Room Temperature ◽

Magnetic Hysteresis ◽

Hysteresis Loops ◽

Relative Dielectric Constant ◽

Tunneling Magnetoresistance ◽

Organic Layer ◽

Chemical Inertness ◽

Metal Organic ◽

Pulsed Electron Deposition ◽

Magnetic Hysteresis Loops

Nano films of polytetrafluoroethylene (PTFE; commercially coded as Teflon) shows advantage over inorganic spacer materials like Al2O3 and MgO in fabricating tunneling magneto resistive devices due to its relative dielectric constant and chemical inertness to provide a homogenous metal-organic interface. Pulsed electron deposition proves useful in fabricating such thin PTFE films (3-6 nm) for trilayer device such as Fe (100 nm)/ PTFE (3-6 nm) /Fe (100 nm) on Si (100). Characteristic magnetic hysteresis loops demonstrating the magnetic tunnel junctions were realized for a PTFE organic layer thickness >3 nm. The tunneling magnetoresistance measurement at room temperature shows a typical magneto resistive feature, increasing with increasing PTFE thickness.

Download Full-text

ROOM TEMPERATURE FERROMAGNETISM IN PURE AND Cu DOPED ZnO NANORODS: ROLE OF COPPER OR DEFECTS

Functional Materials Letters ◽

10.1142/s179360471100152x ◽

2011 ◽

Vol 04 (01) ◽

pp. 17-20 ◽

Cited By ~ 20

Author(s):

SHALENDRA KUMAR ◽

B. H. KOO ◽

C. G. LEE ◽

SANJEEV GAUTAM ◽

K. H. CHAE ◽

...

Keyword(s):

Room Temperature ◽

Room Temperature Ferromagnetism ◽

Zno Nanorods ◽

Magnetic Hysteresis ◽

Green Emission ◽

Secondary Phase ◽

Magnetic Hysteresis Loop ◽

Cu Doping ◽

Doped Zno

We report structural, magnetic and electronic structure studies of pure and Cu doped ZnO nanorods with the aim to understand the origin of ferromagnetism. A structural study indicates that all the samples exhibit single phase nature and rules out the formation of secondary phase. NEXAFS measurements reveal that Cu ions exist in Cu 2+ state. Magnetic hysteresis loop measurements reflect that the pure and Cu doped ZnO nanorods exhibit room temperature ferromagnetism. The increase in the intensity of green emission in photoluminescence study indicates that defects density increases with Cu doping.

Download Full-text