scholarly journals Effect of argon annealing method on structural and ferromagnetic properties in Fe-doped SnO2 powders

2021 ◽  
Vol 2145 (1) ◽  
pp. 012031
Author(s):  
S Nongkae ◽  
K Tangphanit ◽  
S Teeta ◽  
E Swatsitang ◽  
K Wongsaprom
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Ferromagnetic State ◽  
Nanocrystalline Powders ◽  
Ferromagnetic Behavior ◽  
Ferromagnetic Coupling ◽  
Calcination Process ◽  
Fe Content ◽  
F Center ◽  
Annealing Method

Abstract Nanocrystalline powders of Fe-doped SnO2 (Sn1-xFexO2) (x = 0.00, 0.01, 0.03, 0.05) were prepared by a hydrothermal method. The powders were calcined in argon atmosphere at 600 °C for 2 h, causing phase transition from diamagnetic and weak ferromagnetic behavior to a ferromagnetic state. No trace and other magnetic impurity phases was detected in the samples with Fe content up to 3%. The calcined samples of Fe-doped SnO2 revealed the room temperature ferromagnetism with highest magnetization values of 434.07 memu/g at 15 kOe for x = 0.05. The room temperature ferromagnetism of samples originated from oxygen vacancies that occurred in the argon calcination process. In particular, oxygen vacancy shows a significant role in ferromagnetic coupling corresponding to F-center interaction.

Room-temperature ferromagnetism in MgO nanocrystalline powders

2008 ◽  
Vol 93 (19) ◽  
pp. 192503 ◽  
Author(s):  
Jifan Hu ◽  
Zhongli Zhang ◽  
Ming Zhao ◽  
Hongwei Qin ◽  
Minhua Jiang
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Nanocrystalline Powders

Structural and Magnetic Properties of Cobalt and Aluminum Co-Doped ZnO Powders

2008 ◽  
Vol 47-50 ◽  
pp. 600-603
Author(s):  
Yan Yan Wei ◽  
Deng Lu Hou ◽  
Rui Bin Zhao ◽  
Zhen Zhen Zhou ◽  
Cong Mian Zhen ◽  
...  
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Sol Gel ◽  
Ferromagnetic Behavior ◽  
Infrared Transmission ◽  
X Ray Diffraction ◽  
Al Content ◽  
Infrared Reflection ◽  
Zno Powders ◽  
Ft Ir

A series of Zn0.95-xCo0.05AlxO (x=0, 0.01, 0.02, 0.05, 0.08, 0.10) powders with different percentages of aluminum was fabricated using the sol-gel method. X-ray diffraction (XRD) revealed that the Co ions and Al ions substitute for Zn2+ ions without changing the wurtzite structure. No impurity phases were found. No clusters or precipitates of cobalt or aluminum were found using scanning electron microscope analysis. Fourier transform-infrared reflection (FT-IR) spectrometry was used to examine the infrared transmission properties and revealed that Co ions were incorporated into the lattice as Co2+ substituting for Zn2+. Ferromagnetic behavior in the samples was obtained at room temperature. As the Al content x increased, the room temperature ferromagnetism of the samples was reduced, and when x increased to 0.08, the room temperature ferromagnetism disappeared.

Hydrothermal Synthesis and Room Temperature Ferromagnetism of Ni-Doped Rod-Like ZnO Particles

2014 ◽  
Vol 934 ◽  
pp. 71-74
Author(s):  
Lian Mao Hang ◽  
Zhao Ji Zhang ◽  
Zhi Yong Zhang
Keyword(s):  
Quantum Interference ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Hexagonal Wurtzite Structure ◽  
Ferromagnetic Behavior ◽  
Secondary Phases ◽  
Superconducting Quantum Interference Device ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zno Particles

Ni-doped rod-like ZnO particles with doping concentration of 1 at.% were synthesized at 200°C by hydrothermal method and characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and superconducting quantum interference device (SQUID). The results show that the as-synthesized samples are pure hexagonal wurtzite structure without metallic Ni or other secondary phases and display rod-like shape with smooth surface. The magnetization measurements reveal that the Ni-doped rod-like ZnO particles show ferromagnetic behavior at room temperature. The saturation magnetization and coercive field are 0.0046 emu/g and 15 Oe, respectively.

scholarly journals Ferromagnetism from non-magnetic ions: Ag-doped ZnO

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Nasir Ali ◽  
Vijaya A. R. ◽  
Zaheer Ahmed Khan ◽  
Kartick Tarafder ◽  
Anuvesh Kumar ◽  
...  
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Magnetic Coupling ◽  
Ferromagnetic State ◽  
Coupling Energy ◽  
Unpaired Spin ◽  
Magnetic Ions ◽  
Doped Zno ◽  
Ferromagnetic Ordering ◽  
Magnetic Ion

AbstractTo develop suitable ferromagnetic oxides with Curie temperature (TC) at or above room temperature for spintronic applications, a great deal of research in doping ZnO with magnetic ions is being carried out over last decade. As the experimental results on magnetic ions doped ZnO are highly confused and controversial, we have investigated ferromagnetism in non-magnetic ion, Ag, doped ZnO. When Ag replaces Zn in ZnO, it adopts 4d9 configuration for Ag2+ which has single unpaired spin and suitable exchange interaction among these spins gives rise to ferromagnetism in ZnO with above room temperature TC. Experimentally, we have observed room temperature ferromagnetism (RTFM) in Ag-doped ZnO with Ag concentration varied from 0.03% to 10.0%. It is shown that zinc vacancy (VZn) enhances the ferromagnetic ordering (FMO) while oxygen vacancy (VO) retards the ferromagnetism in Ag-doped ZnO. Furthermore, the theoretical investigation revealed that VZn along with Ag2+ ions play a pivotal role for RTFM in Ag-doped ZnO. The Ag2+-Ag2+ interaction is ferromagnetic in the same Zn plane whereas anti-ferromagnetic in different Zn planes. The presence of VZn changes the anti-ferromagnetic to ferromagnetic state with a magnetic coupling energy of 37 meV. Finally, it has been established that the overlapping of bound magnetic polarons is responsible for RTFM in low doping concentration. However, anti-ferromagnetic coupling sets in at higher doping concentrations and hence weakens the FMO to a large extent.

Dopant Induced Room Temperature Ferromagnetism in Fe-Doped CdS Nanoparticles

2012 ◽  
Vol 584 ◽  
pp. 178-181
Author(s):  
G. Murali ◽  
D. Amaranatha Reddy ◽  
B. Poornaprakash ◽  
R.P. Vijayalakshmi ◽  
N. Madhusudhana Rao
Keyword(s):  
Room Temperature ◽  
Bulk Material ◽  
Room Temperature Ferromagnetism ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Cds Nanoparticles ◽  
Ferromagnetic Behavior ◽  
Magnetic Studies ◽  
Wet Chemical ◽  
Diamagnetic Behavior

Room temperature ferro-magnetism in Fe-doped CdS nanoparticles (NPs) synthesized by a wet chemical precipitation method is reported. Magnetic studies revealed that pure CdS NPs exhibit diamagnetic behavior as like bulk material, where as 3% Fe doped CdS NPs shows the ferromagnetic behavior. At room temperature, ESR signal characteristic of Fe3+ was observed in doped NPs.

Ferromagnetic Properties in Co-Substituted Titania Nanosheets

2008 ◽  
Vol 388 ◽  
pp. 119-122
Author(s):  
Minoru Osada ◽  
Yasuo Ebina ◽  
Kazunori Takada ◽  
Takayoshi Sasaki
Keyword(s):  
First Principles ◽  
Room Temperature ◽  
Magnetic Circular Dichroism ◽  
Room Temperature Ferromagnetism ◽  
Ferromagnetic State ◽  
Optical Measurements ◽  
Induced Anisotropy ◽  
2D System ◽  
Exhibit Room Temperature Ferromagnetism ◽  
Strong Spin

Two-dimensional (2D) Ti1-xCoxO2 nanosheet, a recently discovered ferromagnic nanomaterial, has been investigated by magnetic and magneto-optical measurements. The multilayer films of Ti0.8Co0.2O2 nanosheets exhibit room-temperature ferromagnetism with magnetic moment of 1.4 μ B/Co. We also observe robust magnetic circular dichroism near the absorption edge at 4 eV, indicating a strong spin polarization in this 2D system. The first-principles study of Ti1-xCoxO2 nanosheet characterizes the ferromagnetic state with a spin-orbit-induced anisotropy.

THE GROWTH AND CHARACTERIZATION OF ROOM TEMPERATURE FERROMAGNETIC WIDEBAND-GAP MATERIALS FOR SPINTRONIC APPLICATIONS

2006 ◽  
Vol 16 (02) ◽  
pp. 515-543
Author(s):  
MATTHEW H. KANE ◽  
MARTIN STRASSBURG ◽  
WILLIAM E. FENWICK ◽  
ALI ASGHAR ◽  
IAN T. FERGUSON
Keyword(s):  
Room Temperature ◽  
Magnetic Semiconductors ◽  
Room Temperature Ferromagnetism ◽  
Dilute Magnetic Semiconductors ◽  
Chemical Vapor ◽  
Wide Bandgap ◽  
Organic Chemical ◽  
Ferromagnetic Behavior ◽  
Spintronic Devices

Wide-bandgap dilute magnetic semiconductors (DMS), such as transition-metal doped ZnO and GaN , have gained attention for use in spintronic devices because of predictions and experimental reports of room temperature ferromagnetism which may enable their use in spintronic devices. However, there has been some debate over the source of ferromagnetism in these materials. This paper focuses on the high quality growth of wide bandgap DMS, and the characterization of Zn 1-x Mn x O produced by melt-growth techniques and Ga 1-x Mn x N grown by metal organic chemical vapor deposition (MOCVD). High resolution X-ray diffraction results revealed no second phases in either the ZnO crystals or the GaN films. Undoped as-grown, bulk crystals of Zn 1-x Mn x O and Zn 1-x Co x O crystals are shown to be paramagnetic at all temperatures. In contrast, the Ga 1-x Mn x N films showed ferromagnetic behavior at room temperature under optimum growth conditions. Experimental identification of the Mn ion charge state and the presence of bands in the bandgap of GaN are investigated by optical spectroscopy and electron spin paramagnetic resonance (EPR). It is shown that the broadening of states in the Mn 3d shell scaled with Mn concentration, and that optical transitions due to this band correlated with the strong ferromagnetism in these samples. However, this band disappeared with an increase in free electron concentration provided by either annealing or doping. Raman studies of Ga 1-x Mn x N revealed two predominant Mn -related modes featured with increasing concentration, a broad disorder related structure at 300cm-1 and a sharper peak at 669cm-1 This works show that the development of practical ferromagnetic wide bandgap DMS materials for spintronic applications will require both the lattice site introduction of Mn as well as careful control of the background defect concentration to optimize these materials.

Search for Room Temperature Ferromagnetism in Low-Concentration Transition Metal Doped ZnO Nanocrystalline Powders Using a Microscopic Technique

2010 ◽  
Vol 46 (6) ◽  
pp. 1780-1783 ◽  
Author(s):  
Rakesh Dogra ◽  
Artur W. Carbonari ◽  
Márcio E. Mercurio ◽  
Moacir R. Cordeiro ◽  
Juliana M. Ramos ◽  
...  
Keyword(s):  
Transition Metal ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Nanocrystalline Powders ◽  
Microscopic Technique ◽  
Low Concentration ◽  
Doped Zno ◽  
Metal Doped

scholarly journals Improving the Room-Temperature Ferromagnetism in ZnO and Low-Doped ZnO:Ag Films Using GLAD Sputtering

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5337
Author(s):  
Marcio A. Correa ◽  
Armando Ferreira ◽  
Raphael M. Tromer ◽  
Leonardo D. Machado ◽  
Matheus Gamino ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Ferromagnetic Metal ◽  
Zno Films ◽  
Ferromagnetic Behavior ◽  
Sensor Element ◽  
Promising Candidate ◽  
Doped Zno ◽  
Metal Doped

ZnO and doped ZnO films with non-ferromagnetic metal have been widely used as biosensor elements. In these studies, the electrochemical measurements are explored, though the electrical impedance of the system. In this sense, the ferromagnetic properties of the material can be used for multifunctionalization of the sensor element using external magnetic fields during the measurements. Within this context, we investigate the room-temperature ferromagnetism in pure ZnO and Ag-doped ZnO films presenting zigzag-like columnar geometry. Specifically, we focus on the films’ structural and quasi-static magnetic properties and disclose that they evolve with the doping of low-Ag concentrations and the columnar geometry employed during the deposition. The magnetic characterization reveals ferromagnetic behavior at room temperature for all studied samples, including the pure ZnO one. By considering computational simulations, we address the origin of ferromagnetism in ZnO and Ag-doped ZnO and interpret our results in terms of the Zn vacancy dynamics, its substitution by an Ag atom in the site, and the influence of the columnar geometry on the magnetic properties of the films. Our findings bring to light an exciting way to induce/explore the room-temperature ferromagnetism of a non-ferromagnetic metal-doped semiconductor as a promising candidate for biosensor applications.

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