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1.
Nanocrystalline Zn0.5Mn0.5Fe2O4 was synthesized through the pyrolysis of polyacrylate salt precursors prepared via in situ polymerization of the metal salts and acrylic acid. The pyrolysis behavior of the polymeric precursors was studied by use of thermal analysis. The as-obtained product was characterized by powder X-ray diffraction (XRD), transmission electron microscope (TEM), electron diffraction (ED) pattern, scanning electron microscopy (SEM) and electron dispersive X-ray (EDX) analysis. The results revealed that the particle size is in the range of 15–25 nm for Zn-Mn ferrites with good crystallinity. Magnetic properties of the sample at 300 K were measured using a vibrating sample magnetometer, which showed that the sample exhibited characteristics of superparamagnetism. 相似文献
2.
A simple sonochemical method was developed to synthesis uniform sphere-like Co3O4 and Mn3O4 nanocrystals. Epoxidation of styrene and cyclooctene by anhydrous tert-butyl hydroperoxide over the prepared Co3O4 and Mn3O4 nanocatalysts was investigated. The results of conversion activity were compared with bulk Co3O4 and Mn3O4. Under optimized reaction conditions, the nanocatalysts showed a superior catalytic performance as compared to the bulk catalysts. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and BET surface area, were used to characterize and investigate the nanocatalysts. 相似文献
3.
Layered manganate Ba6Mn5O16 was prepared by a traditional solid-state reaction method and its microstructure at atomic level was investigated in detail by means of high-resolution transmission electron microscopy (HRTEM). Although the sample shows, from the XRD data, a nearly single-phase n=5 layered Ba6Mn5O16 phase of the hexagonal Ban+1MnnO3n+1 homologous series, the presence of numerous structural defects, especially intergrowth faults of the hexagonal Ban+1MnnO3n+1 homologous series with different n in it, was revealed by HRTEM. Furthermore, a minor 2H BaMnO3 phase was also found to coexist with the layered Ba6Mn5O16 phase. These defects could have a correlation with the magnetic properties of the sample, i.e. the TN being very broad and the appearance of the Curie tail in the susceptibility. 相似文献
4.
Nataša Jovi? Vukoman Jokanovi? Dušan Brankovi? Darko Makovec 《Journal of magnetism and magnetic materials》2010,322(21):3271-3277
Nanocomposite made of 10 wt% of Co2.4Al0.6O4 particles dispersed in an amorphous SiO2 matrix has been synthesized by a sol-gel method. X-ray diffraction, transmission electron microscopy and magnetic measurements have been used to characterize the properties of nanocomposite. Most of the particles are well crystallized and have an average diameter below 100 nm. Smaller particles with size below 10 nm have also been observed. A large value of the effective magnetic moment per Co2+ ion of 5.08 μB and negative and the low Curie-Weiss paramagnetic temperature Θ∼−6 K, obtained from the high-temperature susceptibility data, indicate a possible mixing of Co2+ and Co3+ ions between tetrahedral and octahedral sites of the spinel crystal lattice. The measurements of static and dynamic magnetic susceptibilities have shown that Co2.4Al0.6O4 particles in SiO2 matrix display a spin glass behavior at low temperatures. 相似文献
5.
Single crystalline GaN nanoribbons were synthesized through nitriding Ga2O3 thin films deposited on sapphire (0001) substrates by radio frequency magnetron sputtering. The component and structure of nanoribbons were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The flat and smooth ribbon-like nanostructures are high quality single crystalline hexagonal wurtzite GaN. The thickness and width-to-thickness ratio of the grown GaN nanoribbons are in the range of 8-15 nm and ∼5-10, respectively. 相似文献
6.
Green emitting LiGa5O8:Mn powder phosphor has been prepared in a short time by solution combustion method. Powder X-ray diffraction pattern indicated a dominant phase of LiGa5O8 with another secondary LiGaO2 phase. Morphology aspects were studied by using field emission scanning electron microscopy. Upon UV light excitation (296 nm), the phosphor exhibits a strong green luminescence (510 nm), which corresponds to the 4T1→6A1 transition of Mn2+ ions in an environment close to tetrahedral symmetry. EPR spectrum exhibits resonance signals characteristic of Mn2+ ions. It is observed that the spin-Hamiltonian parameters g and A do not vary with temperature. The magnitude of the hyperfine splitting constant (A) in the present study indicates that there exists a moderately covalent bonding between Mn2+ ions and the surrounding ligands. The zero-field splitting parameter (D), spin concentration (N) and paramagnetic susceptibility (χ) have also been evaluated. 相似文献
7.
Single-crystalline Li2MnO3 nanoribbons have been synthesized via the precursor template Na0.44MnO2 nanoribbons in LiNO3-LiCl eutectic molten salt. The as-prepared Li2MnO3 nanoribbons are characterized by a range of methods including X-ray diffractometer, scanning electron microscope, transmission electron microscope, energy dispersive X-ray spectroscopy, and selected-area electron diffraction techniques. Magnetization measurements show that the Li2MnO3 nanoribbons present weak ferromagnetism, spin-glass-like behavior, and exchange bias effect at low temperature. The magnetic behaviors of Li2MnO3 nanoribbons can be interpreted based on a core-shell model. 相似文献
8.
Yong Su Xia Meng Yiqing Chen Qingtao Zhou Ling Li Yi Feng 《Journal of Physics and Chemistry of Solids》2009,70(7):1062-1065
In-doped Ga2O3 zigzag-shaped nanowires and undoped Ga2O3 nanowires have been synthesized on Si substrate by thermal evaporation of mixed powders of Ga, In2O3 and graphite at 1000 °C without using any catalyst via a vapor-solid growth mechanism. The morphologies and microstructures of the products were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and photoluminescence spectroscopy (PL). The nanowires range from 100 nm to several hundreds of nanometers in diameter and several tens of micrometers in length. A broad emission band from 400 to 700 nm is obtained in the PL spectrum of these nanowires at room temperature. There are two blue-emission peaks centering at 450 and 500 nm, which originate from the oxygen vacancies, gallium vacancies and gallium-oxygen vacancy pairs. 相似文献
9.
Fabrication of chain-like Mn2O3 nanostructures via thermal decomposition of manganese phthalate coordination polymers 总被引:1,自引:0,他引:1
Masoud Salavati-Niasari Fatemeh Mohandes Kamal Saberyan 《Applied Surface Science》2009,256(5):1476-1480
A novel manganese coordination polymer [Mn(Pht)(H2O)]n as a precursor was obtained by chemical precipitation involving an aqueous solution of anhydrous manganese acetate and phthalate anion as a potential O-banded ligand. Fourier transform infrared (FT-IR) results proved that phthalate anions coordinate to metal cations as a chelating bidentate ligand, making polymeric structure. The Mn2O3 nanostructures have been prepared via thermal decomposition of as-prepared manganese phthalate polymers as precursor in the presence of oleic acid (OA) and triphenylphosphine (TPP) as a stabilizer and capping. Different approaches such as FT-IR, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were applied to characterize the products. TEM images and XRD analysis indicated that the as-synthesized chain-like Mn2O3 has a crystal phase of cubic syngony with a mean size of ∼40 nm. 相似文献
10.
J.L. Gunjakar 《Applied Surface Science》2008,254(18):5844-5848
The present investigation is related to the deposition of single-phase nano-sheets spinel nickel ferrite (NiFe2O4) thin films onto glass substrates using a chemical method. Nano-sheets nickel ferrite films were deposited from an alkaline bath containing Ni2+ and Fe2+ ions. The films were characterized for their structural, surface morphological and electrical properties by means of X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and two-point probe electrical resistivity techniques. The X-ray diffraction pattern showed that NiFe2O4 nano-sheets are oriented along (3 1 1) plane. The FT-IR spectra of NiFe2O4 films showed strong absorption peaks around 600 and 400 cm−1 which are typical for cubic spinel crystal structure. Microstructural study of NiFe2O4 film revealed nano-sheet like morphology with average sheet thickness of 30 nm. The room temperature electrical resistivity of the NiFe2O4 nano-sheets was 107 Ω cm. 相似文献
11.
A Li2O-B2O3-Al2O3 glass system, un-doped and doped with LiF, and/or TiO2 was synthesized by the fusion method and its physical properties were investigated by thermoluminescence (TL), X-ray diffraction (XRD), electron paramagnetic resonance (EPR), atomic force microscopy (AFM) and differential thermal analysis (DTA). The samples were subjected to γ-rays from a colbalt-60 (60Co) source. These techniques provided evidence of LiF and LiF doped with Ti crystal formation in the glass system. A TL glow peak at about 433 K was sensitive to 60Co γ-rays and showed good linearity with doses and consequently could be used to quantify radiation doses. 相似文献
12.
E. Savarimuthu A. Moses Ezhil Raj S. Ramamurthy C. Sanjeeviraja 《Journal of Physics and Chemistry of Solids》2007,68(7):1380-1389
Transparent conducting indium oxide (In2O3) thin films have been prepared on glass substrates by the simple sol-gel-spin coating technique. These films have been characterized by X-ray diffraction, resistivity and Hall effect measurements, optical transmission, scanning electron microscopy and atomic force microscopy for their structural, electrical, optical and morphological properties. The influence of spin parameters, number of coating, process temperature on the quality of In2O3 films are studied. In the operating range of deposition, 400-475 °C, all the films showed predominant (2 2 2) orientation. Films deposited at optimum process conditions exhibited a resistivity of 2×10−2 Ω cm along with the average transmittance of about 80% in the visible spectral range (400-700 nm). 相似文献
13.
Synthesis and characteristics of multifunctional Fe3O4-SiO2-CdS magnetic-fluorescent nanocomposites
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A luminescent superparamagnetic nanocomposite with an Fe 3 O 4-SiO 2-CdS structure is synthesized.Coated with a silica shell,Fe 3 O 4 nanoparticles and CdS quantum dots (QDs) are successfully assembled together.Analysed from the test results of X-ray diffraction (XRD),transmission electron microscopy (TEM),high resolution transmission electron microscopy (HRTEM),hysteresis loop,and photoluminescence (PL) spectrum,these nanocomposites exhibit superparamagnetic and photoluminescent properties. 相似文献
14.
A low-temperature chemical bath deposition (CBD) technique has been used for the preparation of Mn3O4 thin films onto glass substrates. The kinetic behavior and the formation mechanism of the solid thin films from the aqueous solution have been investigated. Structure (X-ray diffraction and Raman), morphological (atom force microscope), and optical (UV-vis-NIR) characterizations of the deposited films are presented. The results indicated that the deposited Mn3O4 thin films of smooth surface with nanosized grains were well crystalline and the optical bandgap of the film was estimated to be 2.54 eV. 相似文献
15.
Octahedral In2O3 crystals were synthesized by evaporation of a mixture of In2O3 and graphite in a horizontal double-tube system. By adjusting the experimental conditions, In2O3 nanowires and nanobelts were also obtained. The microstructures of the resultant In2O3 materials were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), X-ray diffraction. In addition, the growth mechanism of the octahedral In2O3 crystals was discussed in detail. 相似文献
16.
Saeed Choopani Neda Keyhan Ali Ghasemi Ali Sharbathi Iman Maghsoudi Mohammad Eghbali 《Journal of magnetism and magnetic materials》2009,321(13):1996-2000
The effect of Mn2+Co2+Ti4+ substitution on microwave absorption has been studied for BaCo0.5Mn0.5Ti1.0Fe10O19 ferrite-acrylic resin composites in frequency range from 12 to 20 GHz. X-ray diffraction (XRD), scanning electron microscope (SEM), vibrating sample magnetometer, AC susceptometer and vector network analyzer were used to analyze the structural, magnetic and microwave absorption properties. The results showed that the magnetoplumbite structures for all samples have been formed. Based on microwave measurement on reflectivity, BaCo0.5Mn0.5Ti1.0Fe10O19 may be a good candidate for electromagnetic compatibility and other practical applications at high frequency. 相似文献
17.
ZnAl2O4:Mn green light emitting powder phosphors have been prepared by urea combustion technique involving furnace temperatures about 500 °C in a short time (<5 min). The prepared powders were characterized by X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectrometry and the surface area measurements by a Brunauer-Emmet-Teller (BET) adsorption isotherms. The EPR spectrum exhibits a resonance signal at g≈2.0, which shows a six-line hyperfine structure (hfs). From the EPR spectra the spin-Hamiltonian parameters have been evaluated at room temperature as well as at 110 K. EPR and photoluminescence (PL) studies revealed that manganese ions were present in divalent state and the site symmetry around Mn2+ ions is distorted tetrahedral. The spin concentration (N), the paramagnetic susceptibility (χ) and the zero-field splitting parameter (D) have been evaluated and discussed. The green emission at 511 nm in ZnAl2O4:Mn phosphor is assigned to a transition from the upper 4T1→6A1 ground state of Mn2+ ions. 相似文献
18.
Taher Yousefi Ahmad Nozad Golikand Mohammad Hossein MashhadizadehMustafa Aghazadeh 《Current Applied Physics》2012,12(2):544-549
Uniform and single-crystalline Mn3O4 nano-spheres were synthesized by cathodic electrodeposition at high temperature (80 °C) and low current density (0.25 mA cm−1) on steel electrode. Further the annealed samples were characterized for their structural and morphological properties by means of X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) studies. TEM and SEM images showed that particles have spherical shapes and the average diameter size was about 50 nm. Formation of Mn3O4 compound was confirmed from FTIR studies. The XRD pattern showed that the Mn3O4 exhibit tetragonal hausmannite structure. The results of N2 adsorption-desorption analysis indicated that Mn3O4 nano-sphere has BET surface area of about 177.6 m2 g−1 and average pore diameters of 3 and 4 nm. The possible formation mechanism of Mn3O4 nanostructures has been discussed. The supercapacitive properties of Mn3O4 sample in 0.5 M Na2SO4 electrolyte showed maximum supercapacitance of 235.4 Fg−1 at scan rate 10 mV s−1. Coulumbic efficiency could be kept about 90% during 1000 cycles at 10 mV s−1. 相似文献
19.
Mn3O4 thin films have been prepared by novel chemical successive ionic layer adsorption and reaction (SILAR) method. Further these films were characterized for their structural, morphological and optical properties by means of X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), field emission scanning electron microscopy (FESEM), wettability test and optical absorption studies. The XRD pattern showed that the Mn3O4 films exhibit tetragonal hausmannite structure. Formation of manganese oxide compound was confirmed from FTIR studies. The optical absorption showed existence of direct optical band gap of energy 2.30 eV. Mn3O4 film surface showed hydrophilic nature with water contact angle of 55°. The supercapacitive properties of Mn3O4 thin film investigated in 1 M Na2SO4 electrolyte showed maximum supercapacitance of 314 F g−1 at scan rate 5 mV s−1. 相似文献
20.
A. M. Hashem R. S. El-Taweel H. M. Abuzeid A. E. Abdel-Ghany A. E. Eid H. Groult A. Mauger C.M. Julien 《Ionics》2012,18(1-2):1-9
LiNi1/3Co1/3Mn1/3O2 (LNMCO) powders were formed by a two-step synthesis including preparation of an oxalate precursor by ??chimie douce?? followed by a solid-state reaction with lithium hydroxide. The product was characterized by TG-DTA, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), Raman spectroscopy, electron spin resonance (ESR), and SQUID magnetometry. XRD data revealed well-crystallized layered LNMCO with ??-NaFeO2-type structure (R-3?m space group). Morphology studied by SEM and TEM shows submicronic particles of 400?C800?nm with a tendency to agglomerate. The local structure investigated by vibrational spectroscopy (FTIR, Raman), ESR, and SQUID measurements confirms the well-crystallized lattice with a cation disorder of 2.6% Ni2+ ions in Li(3b) sites. Electrochemical tests were carried out in the potential range 2.5?C4.5?V vs. lithium metal on samples heated at 900?°C for 12?h. Initial discharge capacity is 154 mAh/g at C/5, while a capacity of 82 mAh/g is still delivered at 10 C by the two-step synthesized LiNi1/3Co1/3Mn1/3O2 as cathode material. 相似文献