Ferromagnetism, Raman Spectra and Photoluminescence of Sn0.91Co0.05Ce0.04O2 and Sn0.91Fe0.05Ce0.04O2 Nanorods

2012 ◽  
Vol 488-489 ◽  
pp. 226-229
Author(s):  
Jasneet Kaur ◽  
R.K. Kotnala ◽  
Vinay Gupta ◽  
Kuldeep Chand Verma
Keyword(s):  
Raman Spectroscopy ◽  
Magnetic Measurements ◽  
Room Temperature Ferromagnetism ◽  
Sol Gel ◽  
Stoichiometric Ratio ◽  
Chemical Route ◽  
Structural Modifications ◽  
Co Doping ◽  
Transmission Electron ◽  
20 Nm

In the present work, we have fabricated Sn0.91Co0.05Ce0.04O2 (SCC54) and Sn0.91Fe0.05Ce0.04O2 (SFC54) nanorods by a chemical route similar to sol-gel method. X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, photoluminescence (PL) and magnetic measurements are used to characterize these nanorods. XRD pattern shows the polycrystalline nature of rods and TEM confirms that the diameter of rods lie in the range of 15-20 nm and length 100-200 nm. It is observed that on Ce3+ co-doping, nanoparticles assembled themselves into rod like structures. The SCC54 and SFC54 specimens exhibit room temperature ferromagnetism. Their saturated magnetic moment and phase transition temperature is sensitive to their size and stoichiometric ratio. Raman spectroscopy shows an intensity loss of classical cassiterite SnO2 vibration lines, which is indication of significant structural modifications like crystallinity and nano metric size effects on the vibrational properties. From PL spectra, an intense blue luminescence centred at a wavelength of 532 nm is observed in the prepared SnO2 nanostructures, attributed to oxygen-related defects, introduced during the growth process.

Cr-Doping-Induced Ferromagnetism in CeO2-δ Nanopowders

2014 ◽  
Vol 975 ◽  
pp. 42-49
Author(s):  
Nilson S. Ferreira ◽  
Marcelo Andrade Macedo
Keyword(s):  
Raman Spectroscopy ◽  
Saturation Magnetization ◽  
Calcination Temperature ◽  
Room Temperature ◽  
Magnetic Measurements ◽  
Room Temperature Ferromagnetism ◽  
Sol Gel ◽  
Fluorite Structure ◽  
Sol Gel Process ◽  
Cr Doping

The room-temperature ferromagnetism of Cr-doped cerium oxide (Ce0.96Cr0.04O2δ) nanopowders synthesized using a sol-gel process is reported in this paper. XRD and Raman spectroscopy confirm that the Cr atoms successfully displaced some of the Ce atoms in the CeO2lattice without forming any impure phases. The results also confirmed that all calcined samples exhibited a single-phase fluorite structure. The crystallite size (as confirmed by XRD) and the particle size (as confirmed by Raman spectroscopy) increased as the calcination temperature increased. Magnetic measurements indicated that the room-temperature ferromagnetism of the sample was sensitive to the calcination temperature. When the calcination temperature increased, the saturation magnetization decreased while the coercivity increased, which corresponds to less dense and larger particles. The calcined sample at 400°C exhibited superior magnetic properties with the highest saturation magnetization (Ms) of 2.5 × 10-2emu/g (Hc~ 1.27 kOe). The results of the Raman and X-ray photoelectron spectroscopies suggest that the nature of the observed room temperature ferromagnetism in the samples are likely a result of the oxygen vacancies induced by Cr-doping in CeO2.

Synthesis and Thermal Stability of Nontransformable Tetragonal (ZrO2)0.96(REO1.5)0.04 (Re=Sc3+, Y3+) Nanocrystals

2013 ◽  
Vol 334-335 ◽  
pp. 60-64 ◽  
Author(s):  
Mohammad Reza Loghman-Estark ◽  
Reza Shoja Razavi ◽  
Hossein Edris
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Scanning Electron Microscopy ◽  
Sol Gel ◽  
Average Diameter ◽  
X Ray ◽  
Transmission Electron ◽  
20 Nm ◽  
Thermal Stability Of ◽  
Scanning Electron

Scandia, yttria doped zirconia ((ZrO2)0.96(REO1.5)0.04(RE=Sc3+, Y3+)) nanoparticles were prepared by the modified sol-gel method. The microstructure of the products was characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. Thermal stabillity of SYSZ nanocrystals were also investigated. The SYSZ nanocrystals synthesized with EGM:Zr+4mole ratio 4:1, calcined at 700°C, have average diameter of ~20 nm.

Sol-gel processing of nanocrystalline haematite thin films

1997 ◽  
Vol 12 (6) ◽  
pp. 1441-1444 ◽  
Author(s):  
L. Armelao ◽  
A. Armigliato ◽  
R. Bozio ◽  
P. Colombo
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Single Particles ◽  
X Ray ◽  
Transmission Electron ◽  
Gel Processing

The microstructure of Fe2O3 sol-gel thin films, obtained from Fe(OCH2CH3)3, was investigated by x-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy. Samples were nanocrystalline from 400 °C to 1000 °C, and the crystallized phase was haematite. In the coatings, the α–Fe2O3 clusters were dispersed as single particles in a network of amorphous ferric oxide.

The Structural, Electrical, Magnetic Properties of (Cu, Co) Co-Doped ZnO Thin Film

2014 ◽  
Vol 556-562 ◽  
pp. 429-432
Author(s):  
Ping Cao ◽  
Yue Bai ◽  
Zhi Qu
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Sol Gel ◽  
Hall Effect Measurement ◽  
Ferromagnetic Semiconductors ◽  
Zno Thin Film ◽  
Zno Film ◽  
Co Doping ◽  
Doped Zno ◽  
Co Doped

Successful synthesis of room-temperature ferromagnetic semiconductors, (Cu, Co) co-doped ZnO film is obtained by sol-gel method. It is found that the essential ingredient in achieving room-temperature ferromagnetism is Cu co-doping. By Hall-effect measurement ap-type conductivity was observed for the Cu co-doped films, which induced the room-temperature ferromagnetism.

scholarly journals Microstructure, Mössbauer, and Optical Characterizations of Nanocrystalline α-Fe2O3 Synthesized by Chemical Route

ISRN Ceramics ◽  
2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Abhijit Banerjee ◽  
Soumitra Patra ◽  
Mahuya Chakrabarti ◽  
Dirtha Sanyal ◽  
Mrinal Pal ◽  
...  
Keyword(s):  
Annealing Temperature ◽  
Sol Gel ◽  
Rietveld Analysis ◽  
Ferromagnetic Behavior ◽  
Chemical Route ◽  
Perfect Lattice ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Type Semiconductor ◽  
Crystallite Sizes

Nanocrystalline α-Fe2O3 of crystallite sizes ranging from 18 nm to 54 nm has been prepared by sol gel process and postannealing the powder up to 500C∘. X-ray diffraction and transmission electron microscopy images have been used for determining the average crystallite sizes of the prepared samples. The Rietveld analysis reveals that the “as-prepared” α-Fe2O3 powders are not completely stoichiometric, and significant (~20%) oxygen vacancies are noticed in the α-Fe2O3 lattice. Oxygen atoms in as-prepared sample are significantly displaced and the lattice is heavily distorted. With increasing annealing temperature the lattice approaches towards the stoichiometric oxygen concentration and perfect lattice configuration. Mössbauer spectrum of the unannealed (as-prepared) α-Fe2O3 sample shows the superparamagnetic behavior at room temperature whereas all annealed samples show complete ferromagnetic behavior. Optical band gaps of these nanocrystalline α-Fe2O3 samples have been measured from UV-Vis spectroscopy and found to decrease from 2.65 eV to 2.50 eV, like an n-type semiconductor, with increasing annealing temperature up to 500C∘.

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).

Domain structures in Pb(Zr, Ti)O3 and PbTiO3 thin films

1997 ◽  
Vol 12 (10) ◽  
pp. 2612-2616 ◽  
Author(s):  
L. D. Madsen ◽  
E. M. Griswold ◽  
L. Weaver
Keyword(s):  
Thin Films ◽  
Classification Scheme ◽  
Sol Gel ◽  
Chemical Vapor ◽  
Nucleation And Growth ◽  
Grain Sizes ◽  
Domain Structures ◽  
Transmission Electron ◽  
20 Nm ◽  
Gel Processing

The microstructure of Pb(Zr, Ti)O3 (PZT) and PbTiO3 (PT) thin films deposited by the sol-gel method and chemical vapor deposition, respectively, were examined by transmission electron microscopy (TEM). Domains with ∼7 and ∼20 nm widths were found for the PZT and PT thin films, respectively. The traditional parallel twin or wedge-type structures found in bulk ceramics have been observed in thin films. Differences between observed grain sizes and previous studies of similar compounds (in bulk form) are accounted for by geometrical considerations related to crystallographic factors. Finally, a classification scheme for domains in PZT and PT thin films based on these and other published results of several researchers is presented. Domain sizes varied according to three categories: mono-domains (2–50 nm in diameter), domains in spherulite lamellae (28–130 nm wide), and twins in conventional large grains (5–150 nm wide). The mono-domains are related to small grain sizes, while the lamellae are a function of the nucleation and growth associated with sol-gel processing.

Functionalized Silicate Supported TiO2-ZnO Nanocomposite Film and its Application in Simultaneous Photocatalytic Degradation of Toxic Molecules

2013 ◽  
Vol 764 ◽  
pp. 255-265 ◽  
Author(s):  
R. Dhanalakshmi ◽  
A. Pandikumar ◽  
R. Ramaraj
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Xrd Analysis ◽  
Potential Candidate ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Chemical Route ◽  
Molar Ratios ◽  
Amine Functionalized ◽  
Transmission Electron

The TiO2-ZnO nanocomposite materials ((TiO2-ZnO)NCM) with different molar ratios (Ti:Zn) was synthesized by chemical route and dispersed in functionalized silicate sol-gel matrix (Silicate/(TiO2-ZnO)NCM)). The as prepared Silicate/(TiO2-ZnO)NCM were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The dispersion of the small amount of (TiO2-ZnO)NCM in silicate sol-gel matrix paves the way for the preparation of solid-state thin film photocatalyst which is advantageous for the separation of the catalyst from solution, the substrates and the reaction products. The simultaneous photoinduced oxidation of methylene blue (MB) dye and reduction of Cr (VI) to Cr (III) was examined at different amine functionalized silicate sol-gel embedded (TiO2-ZnO)NCM films. The (TiO2-ZnO)NCM dispersed into the amine functionalized silicate sol-gel matrix (TPDT) exhibited enhanced photocatalytic activity when compared to the (TiO2-ZnO)NCM without the silicate sol-gel. The functionalized silicate sol-gel supported (TiO2-ZnO)NCM is a potential candidate for energy conversion and environment remediation and cleaning applications.

Effect of fuel content on formation of zinc aluminate nano and micro-particles synthesised by high rate sol–gel autoignition of glycine-nitrates

2016 ◽  
Vol 70 (3) ◽  
Author(s):  
Shiva Salem
Keyword(s):  
Thermal Analyses ◽  
Sol Gel ◽  
High Rate ◽  
Zinc Aluminate ◽  
X Ray Diffraction ◽  
Micro Particles ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Average Size ◽  
20 Nm

AbstractThe autoignition technique using glycine as fuel and related nitrate salts as an oxidiser is able to produce zinc aluminate spinel. The precursors were synthesised with lean and rich fuel at pH of 7.0 and the materials so obtained were calcined at various temperatures ranging from 600-1200°C. The autoignition process of precursors was studied by the simultaneous thermo-gravimetric and differential thermal analyses to determine the ignition mechanism. The calcined powders were characterised by X-ray diffraction, Brunauer-Emmett-Teller technique and transmission electron microscopy. The product contains nano-sized particles with an average size of approximately 20 nm. The XRD patterns showed the formation of ZnO in the powder obtained by the fuel-rich precursor and calcined at 600°C which disappears at 800°C due to solid-state reaction and proper crystallisation after heat treatment. The results presented here can be useful in manufacturing nano and micro-sized ZnAl

scholarly journals Structural and Magnetic Properties of Microwave Assisted Sol-Gel Synthesized La0.9Sr0.1MnO3 Manganite Nanoparticles

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Mahin Eshraghi ◽  
Parviz Kameli
Keyword(s):  
Magnetic Properties ◽  
Magnetic Measurements ◽  
Sol Gel ◽  
Hysteretic Behavior ◽  
Rhombohedral Structure ◽  
Susceptibility Data ◽  
Slowing Down ◽  
Transmission Electron ◽  
Manganite Nanoparticles ◽  
Structural And Magnetic Properties

The structural and magnetic properties of nanoparticles of La0.9Sr0.1MnO3 (LSMO) were studied using powder X-ray diffraction (XRD), transmission electron microscope (TEM), and magnetic measurements. The XRD refinement result indicates that samples crystallize in the rhombohedral structure with R-3C space group. The dc magnetization measurements revealed that samples exhibit no hysteretic behavior at room temperature, symptomatic of the superparamagnetic (SPM) behavior. The results of ac magnetic susceptibility measurements show that the susceptibility data are not in accordance with the Néel-Brown model for SPM relaxation but fit well with conventional critical slowing down model which indicates that the dipole-dipole interactions are strong enough to cause superspin-glass-like phase in LSMO samples.

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