INFLUENCE OF Co DOPING ON STRUCTURAL, OPTICAL AND MAGNETIC STUDIES OF Co-DOPED CeO2 NANOPARTICLES

NANO ◽  
2010 ◽  
Vol 05 (06) ◽  
pp. 349-355 ◽  
Author(s):  
SHALENDRA KUMAR ◽  
B. H. KOO ◽  
S. K. SHARMA ◽  
M. KNOBEL ◽  
C. G. LEE
Keyword(s):  
Magnetic Measurements ◽  
Magnetic Semiconductors ◽  
Dilute Magnetic Semiconductors ◽  
Weak Ferromagnetism ◽  
Average Particle ◽  
Magnetic Studies ◽  
Co Doping ◽  
Diffraction Patterns ◽  
Co Precipitation ◽  
Co Doped

We have used the co-precipitation technique to synthesize nanocrystalline Co -doped CeO2 dilute magnetic semiconductors with Co concentrations ranging from 0.0–0.07. X-ray diffraction patterns (XRD) demonstrate that all the samples display single phase cubic structure without any impurity phase. Average particle sizes calculated from XRD and transmission electron microscopy (TEM) studies showed a gradual decrease with increase in Co ions concentration. UV–visible optical spectroscopy measurements reflect an energy band gap, which decreases with the increasing concentration of dopant (x ≤ 0.03). Raman spectra show an intensity loss of classical CeO2 vibration modes, which is an indication of considerable structural modifications and disorder in CeO2 lattice. Magnetic measurements revealed that all the samples exhibit a weak ferromagnetism at room temperature.

scholarly journals Increased room temperature ferromagnetism in Co-doped tetrahedral perovskite niobates

2021 ◽  
Vol 8 (10) ◽  
Author(s):  
Yi Zhou ◽  
Qing He ◽  
Fei Zhou ◽  
Xingqi Liao ◽  
Yong Liu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Magnetic Semiconductors ◽  
Room Temperature Ferromagnetism ◽  
Dilute Magnetic Semiconductors ◽  
Defect Band ◽  
Co Doping ◽  
Band Absorption ◽  
Local Spin Polarization ◽  
Curie Temperatures ◽  
Co Doped

Dilute magnetic semiconductors (DMSs), such as (In, Mn)As and (Ga, Mn)As prototypes, are limited to III–V semiconductors with Curie temperatures ( T c ) far from room temperature, thereby hindering their wide application. Here, one kind of DMS based on perovskite niobates is reported. BaM x Nb (1− x ) O 3− δ ( M = Fe, Co) powders are prepared by the composite-hydroxide-mediated method. The addition of M elements endows BaM x Nb (1− x ) O 3− δ with local ferromagnetism. The tetragonal BaCo x Nb (1− x ) O 3− δ nanocrystals can be obtained by Co doping, which shows strong saturation magnetization ( M sat ) of 2.22 emu g −1 , a remnant magnetization ( M r ) of 0.084 emu g −1 and a small coercive field ( H c ) of 167.02 Oe at room temperature. The ab initio calculations indicate that Co doping could lead to a 64% local spin polarization at the Fermi level ( E F ) with net spin DOS of 0.89 electrons eV −1 , this result shows the possibility of maintaining strong ferromagnetism at room temperature. In addition, the trade-off effect between the defect band absorption and ferromagnetic properties of BaM x Nb (1− x ) O 3− δ is verified experimentally and theoretically.

Preparation, Characterization, Electrical and Magnetic Properties of Mn-Doped Dilute Magnetic Semiconductors

2016 ◽  
Vol 15 (05n06) ◽  
pp. 1660004
Author(s):  
Samiksha Malik ◽  
Komal Mohite ◽  
Pranav Naik ◽  
R. B. Tangsali
Keyword(s):  
Magnetic Measurements ◽  
Magnetic Semiconductors ◽  
Average Particle Size ◽  
Dilute Magnetic Semiconductors ◽  
Synthesis Process ◽  
Average Particle ◽  
Temperature Dependent ◽  
Text Type ◽  
Electrical And Magnetic Properties ◽  
Mn Doped

Nanoparticle dilute magnetic semiconductors (DMS) are becoming increasingly important due to their possible applications in spintronics, an emerging field where the conduction process in the materials is a spin-based process. Nanoparticles of Mn-doped ZnO (DMS) material with general formula Zn[Formula: see text]MnxO ([Formula: see text]) were prepared by opting single stage combustion synthesis process. The samples characterized, exhibited formation of monophasic nanoparticles of the sample with average particle size ranging between 17 nm to 23 nm. The calculations of energy bandgap made from UV absorption spectra showed variation of the bandgap from 2.18 eV to 2.32 eV. The magnetic measurements (VSM) made on the samples confirmed formation of a single diamagnetic (Zn[Formula: see text]Mn[Formula: see text]) and two namely (Zn[Formula: see text]Mn[Formula: see text]) (Zn[Formula: see text]Mn[Formula: see text]) paramagnetic samples. It is interesting to see that all the three magnetic profiles exhibit hysteresis type behavior both in diamagnetic form and paramagnetic form. The resistivity of the samples was of the order of 10[Formula: see text] Ohm-cm ([Formula: see text]-cm) at lower temperatures. Temperature-dependent resistivity curves exhibited peaking behavior for all the three samples which is very interesting. Temperature-dependent thermo-power profiles give an indication of [Formula: see text]-type semiconductor behavior with significantly deep and broad minima around 100[Formula: see text] which becomes sharper for sample with higher Mn concentration.

scholarly journals The Al Doping Effect on Epitaxial (In,Mn)As Dilute Magnetic Semiconductors Prepared by Ion Implantation and Pulsed Laser Melting

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4138
Author(s):  
Ye Yuan ◽  
Yufang Xie ◽  
Ning Yuan ◽  
Mao Wang ◽  
René Heller ◽  
...  
Keyword(s):  
Curie Temperature ◽  
Ion Implantation ◽  
Diluted Magnetic Semiconductors ◽  
Laser Annealing ◽  
Magnetic Semiconductors ◽  
Dilute Magnetic Semiconductors ◽  
Pulsed Laser ◽  
Laser Melting ◽  
Co Doping ◽  
Diluted Magnetic

One of the most attractive characteristics of diluted ferromagnetic semiconductors is the possibility to modulate their electronic and ferromagnetic properties, coupled by itinerant holes through various means. A prominent example is the modification of Curie temperature and magnetic anisotropy by ion implantation and pulsed laser melting in III–V diluted magnetic semiconductors. In this study, to the best of our knowledge, we performed, for the first time, the co-doping of (In,Mn)As diluted magnetic semiconductors by Al by co-implantation subsequently combined with a pulsed laser annealing technique. Additionally, the structural and magnetic properties were systematically investigated by gradually raising the Al implantation fluence. Unexpectedly, under a well-preserved epitaxial structure, all samples presented weaken Curie temperature, magnetization, as well as uniaxial magnetic anisotropies when more aluminum was involved. Such a phenomenon is probably due to enhanced carrier localization introduced by Al or the suppression of substitutional Mn atoms.

Structural, magnetic and optical investigations of Fe and Ni co-doped TiO2 dilute magnetic semiconductors

2018 ◽  
Vol 44 (15) ◽  
pp. 17767-17774 ◽  
Author(s):  
Salma Waseem ◽  
Safia Anjum ◽  
Lubna Mustafa ◽  
Tallat Zeeshan ◽  
Zohra Nazir Kayani ◽  
...  
Keyword(s):  
Magnetic Semiconductors ◽  
Dilute Magnetic Semiconductors ◽  
Doped Tio2 ◽  
Co Doped

STRUCTURAL, SURFACE MORPHOLOGICAL AND MAGNETIC STUDIES OF Zn1−xFexS (x=0.00–0.10) DILUTED MAGNETIC SEMICONDUCTORS GROWN BY CO-PRECIPITATION METHOD

2018 ◽  
Vol 25 (01) ◽  
pp. 1850044
Author(s):  
M. HASSAN ◽  
M. GHAZANFAR ◽  
N. AROOJ ◽  
S. RIAZ ◽  
S. SAJJAD HUSSAIN ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Diluted Magnetic Semiconductors ◽  
Magnetic Semiconductors ◽  
Hysteresis Loops ◽  
Secondary Phase ◽  
Precipitation Method ◽  
Ferromagnetic Behavior ◽  
Magnetic Studies ◽  
Diluted Magnetic ◽  
Co Precipitation

We have fabricated Zn[Formula: see text]FexS ([Formula: see text], 0.02, 0.04, 0.06, 0.08 and 0.10) diluted magnetic semiconductors using co-precipitation method. X-ray diffraction patterns depict that Zn[Formula: see text]FexS appears as a dominant phase with cubic zinc blende structure and nanoscale crystallite size. In addition, a secondary phase of rhombohedral ZnS also appears; however, no additional phase arises that primarily belongs to Fe dopant. Using Debye–Scherrer relation, the crystallite size is found to be in the range of 20–27[Formula: see text]nm, which is in good agreement with the crystallite size calculated using the Williamson–Hall (WH) plot method. The appearance of secondary phase provoked to study the residual strain using Stokes–Wilson equation, which is nearly consistent to that observed using WH plot method. The surface morphology, revealed using scanning electron microscopy, depicts non-uniform surface structure with a variety of grains and void dimensions. Hysteresis loops measured for Zn[Formula: see text]FexS at room temperature (RT) illustrate a paramagnetic behavior at higher fields; however, small ferromagnetic behavior is evident due to the small openings of the measured hysteresis loops around the origin. The measured RT ferromagnetism reveals the potential spintronic device applications of the studied diluted magnetic semiconductors.

scholarly journals Synthesis and Characterization of Co2+ Ions Doped ZnS-CdS Composite Nanopowder

2020 ◽  
Author(s):  
Madhavi Jonnalagadda
Keyword(s):  
Average Particle Size ◽  
Exchange Interactions ◽  
Host Lattice ◽  
Material Surface ◽  
Precipitation Process ◽  
Average Particle ◽  
Magnetic Studies ◽  
Chemical Homogeneity ◽  
Ferromagnetic Nature ◽  
Co Precipitation

ZnS-CdS composite nano-powder doped with (0.01 mol %) Cobalt has been collected by a co-precipitation process at 300 K. The sample is characterized by structural, combined spectroscopic methods and magnetic studies. The prepared samples were belonging to cubic structure no impurity phases were observed. Doping of cobalt increase the neighborhood strain assessment and a decreases lattice constants decides from x-ray diffraction data. The crystallite size is 10.42nm. From UV-absorption and EPR studies revealed that the energy band gap of Co2+ doped ZnS-CdS composite nanopowder and extension of sp-d exchange interactions and common d-d transitions. The variation in the energy bandgap varies as a function of cobalt concentration is due to structural modification. Photoluminescence spectrum reveals the defect-related emissions and shows the formation of luminescence. FT-IR spectrum confirmed the feature vibrational manner of Zn, Cd, O–H and sulfide ions are in the host lattice. The doping-induced magnetic properties are studied by vibrating sample magnetometer which matches with the theoretical values besides ferromagnetic nature. Magnetic studies confirm the ferromagnetic nature of the material. Surface morphology and chemical homogeneity studies were carried out by using SEM with EDAX. Transmission electron microscope recommends the crystalline nature of nanoparticles, with average particle size is of the order of 20-100nm.

scholarly journals Physical Investigations of (Co, Mn) Co-Doped ZnO Nanocrystalline Films

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1507
Author(s):  
Bechir Yahmadi ◽  
Olfa Kamoun ◽  
Badriyah Alhalaili ◽  
Safia Alleg ◽  
Ruxandra Vidu ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Magnetic Measurements ◽  
Texture Coefficient ◽  
Room Temperature Ferromagnetism ◽  
Band Gap Energy ◽  
X Ray ◽  
Co Doping ◽  
Glass Substrates ◽  
Doped Zno ◽  
Co Doped

Undoped as well as (Co, Mn) co-doped Zinc oxides have been effectively developed on glass substrates, taking advantage of the spray pyrolysis procedure. The X-ray diffraction XRD as well as X-ray photoelectron spectroscopy (XPS) measurements have recognized a pure hexagonal wurtzite form of ZnO, and no other collateral phases such as MnO2 or CoO2 have been observed as a result of doping. The calculated values of the texture coefficient (TC) were between 0.15 and 5.14, indicating a dominant orientation along the (002) plane. The crystallite size (D) varies with the (Co, Mn) contents. The dislocation density (δ) as well as the residual microstrains increased after Co and Mn doping. Furthermore, the surface morphology of the films has been affected significantly by the Co and Mn incorporation, as shown by the scanning electron microscopy (SEM) investigation. The study of the optical properties exhibits a red shift of the band gap energy (Eg) with the (Co, Mn) co-doping. The magnetic measurements have shown that the undoped and (Co, Mn) co-doped ZnO thin films displayed room-temperature ferromagnetism (RTFM).

Optical Properties and Ferromagnetism of Fe and Ni Co-doped ZnO Dilute Magnetic Semiconductors

2014 ◽  
Vol 35 (2) ◽  
pp. 178-183
Author(s):  
魏智强 WEI Zhi-qiang ◽  
张玲玲 ZHANG Ling-ling ◽  
武晓娟 WU Xiao-juan ◽  
吴永富 WU Yong-fu ◽  
王璇 WANG Xuan
Keyword(s):  
Optical Properties ◽  
Magnetic Semiconductors ◽  
Dilute Magnetic Semiconductors ◽  
Doped Zno ◽  
Co Doped
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