scholarly journals Hydrothermal redox synthesis of cobalt and manganese spinels using metal nitrates

2019 ◽  
Vol 60 (10) ◽  
pp. 116-123
Author(s):  
Aygul A. Mammadova ◽  
◽  
Sevinj N. Osmanova ◽  
Sabira A. Agayeva ◽  
Aydar A. Mejidov ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Manganese Oxide ◽  
Spinel Phase ◽  
Manganese Carbonate ◽  
Average Particle ◽  
Particle Sizes ◽  
Reaction Products ◽  
X Ray ◽  
Temperature Range ◽  
Hydrothermal Reduction

The hydrothermal reduction of cobalt, manganese and lithium nitrates with ethylene glycol was studied in the temperature range 100-270 оС in order to obtain nanostructured spinels. The phase composition, particle sizes of the reaction products, and their morphology studied by using IR spectroscopy, X-ray diffractometry, and scanning electron microscopy. We found that the nature of the reaction product of manganese and cobalt nitrates with ethylene glycol (EG) depends on the reaction temperature, the ratio of metal nitrate: ethylene glycol and reaction time. In excess of the reducing agent at temperatures up to 140 оС, observed the formation of metal oxalates. The main product of hydrothermal reduction of manganese nitrate with ethylene glycol at temperatures of 150 оC and 180 оC is manganese oxide Mn3O4 (Hausmanite). At 200 оС obtained the mixture of manganese oxide (Mn3O4) and carbonate (MnCO3). In accordance with the data of X-ray phase analysis at 220 оС and 240 оС, the only reaction product in both cases is manganese carbonate. It was obtained two types of structures on electron-microscopic images of the non-calcined sample at 200 оC: needle-shaped and spherical clusters. It can be assumed that these structures belong to the phases Mn3O4 (Hausmanite) and manganese carbonate MnCO3, respectively. When reduced cobalt nitrate with ethylene glycol in the temperature range 120-220 оC, gives a main amorphous phase, and on X-ray diffraction patterns are observed weak reflections corresponding to cobalt oxide Co3O4. It was shown that upon calcination (at 750 оС) of the samples during the reduction of the mixture of cobalt and manganese nitrates, was obtained the spinel phase of the composition (Co,Mn)(Co,Mn)2O4. In a similar way were obtained Li2CoMn3O8 and LiCoO2 phases (with average particle sizes of 42 nm and 30 nm), which can be used as cathodes in lithium batteries.

Effect of Crystal Orientation Agents on Morphology of Nano-CaCO3

2015 ◽  
Vol 723 ◽  
pp. 544-547
Author(s):  
Xiang Wei Cheng ◽  
Da Jin Xiong ◽  
Chao Huo
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Crystal Orientation ◽  
Average Particle ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
Calcite Crystal ◽  
X Ray ◽  
Different Shapes ◽  
Scanning Electron

Using intermittent bubbling carbonation method to prepare nanoCaCO3, the effect of crystal orientation agents on the morphology of nanoCaCO3 was studied. The nanoCaCO3 was characterized by means of field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), Laser particle analyzer. The results showed that the different shapes nanoCaCO3 was synthesized by adding different crystal orientation agents to control the shape of the product. The as-prepared CaCO3 were pure calcite crystal and the average particle sizes were within the range of 25.7 to 60.9 nm.

Nanostructured OMO type Manganese Oxide – as Novel Support for Palladium towards Electrooxidation of Methanol and Ethylene Glycol

2012 ◽  
Vol 15 (4) ◽  
pp. 249-254 ◽  
Author(s):  
Ramanujam Kannan ◽  
Kulandaivelu Karunakaran ◽  
Samuel Vasanthkumar
Keyword(s):  
Catalytic Activity ◽  
Ethylene Glycol ◽  
Manganese Oxide ◽  
Reduction Method ◽  
Pd Nanoparticles ◽  
Active Oxygen ◽  
Electrolytic Solution ◽  
X Ray ◽  
Supporting Material ◽  
Electrooxidation Of Methanol

Octahedral molecular sieve type manganese oxide (OMO) was synthesized by the ultra sonic assisted hydrothermal method, and was subsequently used as supportive material for palladium (Pd) metal towards the electrooxidation of methanol and ethylene glycol. The Pd nanoparticles were coated on the OMO by insitu reduction method. Low quantity of 5% Pd metal was used and the electrocatalytic activity was studied. The prepared OMO and the OMO/Pd nanocomposite were characterized by powder X–ray diffractogram (XRD), Scanning Electron Microscopy (SEM), Energy dispersive X–ray spectroscopy (EDS) and electrochemical methods. These studies demonstrated that the OMO can act as a good catalyst supporting material. The OMO helps to enhance the catalytic activity of Pd metal by supplying the active oxygen, which is extracted from the electrolytic solution. The electrooxidation of EG shows improved catalytic activity.

Effects of size and surface on luminescence properties of submicron upconversion NaYF4:Yb,Er particles

2009 ◽  
Vol 24 (6) ◽  
pp. 2042-2050 ◽  
Author(s):  
Du Yuan ◽  
Guang Shun Yi ◽  
Gan Moog Chow
Keyword(s):  
Milling Time ◽  
Transition Probability ◽  
Emission Spectra ◽  
Average Particle ◽  
Particle Sizes ◽  
Surface Enrichment ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Dependent ◽  
Peak Broadening

Bulk NaYF4:Yb,Er particles (∼1.4 μm particle size) were synthesized using a hydrothermal method. As-synthesized particles were subsequently ball milled to three average particle sizes, namely, ∼260 nm, 160 nm, and 100 nm. The x-ray diffraction pattern showed an hcp phase for as-synthesized and ball-milled particles with a predominant (100) peak. Room temperature emission spectra showed no size dependent peak shifts or peak broadening. The intensities of both green and red emissions decreased with increasing milling time. Segregation of Er ions was detected on the surfaces of milled particle that reduced the sensitizer-activator transition probability, resulting in decreased emission intensities. The green-to-red emission ratio was correlated to the surface enrichment of Er, which affected the cross-relaxation of luminescence dynamics.

The Location of Tantalum Atoms in Ni3Al

1988 ◽  
Vol 133 ◽  
Author(s):  
Hui Lin ◽  
David P. Pope
Keyword(s):  
Diffraction Method ◽  
Average Particle ◽  
Grinding Process ◽  
Particle Sizes ◽  
X Ray ◽  
Fine Powders ◽  
Superlattice Peak ◽  
Melt Spun ◽  
Simple Substitution ◽  
Melt Spun Ribbons

ABSTRACTAn X-ray powder diffraction method was used to determine the location of tantalum atoms in Ni3Al. A series of Ni3 (Al,Ta) alloys were produced with tantalum content ranging from 0.1 to 3.0 at%. Fine powders with average particle sizes less than 80 pm were made from melt-spun ribbons by a grinding process. The values of the superlattice peak intensities normalized to the intensity of the (200) fundamental peak agreed with the calculated values assuming that tantalum atoms substitute on aluminum sites, not on nickel sites. Thus it is concluded from our experiments that tantalum atoms substitute for aluminum in Ni3Al, except for Ta contents around 0.2 at% where the data can not be interpreted in terms of a simple substitution scheme.

scholarly journals Sintesis Nanopartikel Mangan Oksida dengan Metode Sol Gel dan Uji Aktivitas Katalitik terhadap Degradasi Zat Warna Rhodamin B

2020 ◽  
Vol 21 (2) ◽  
pp. 190
Author(s):  
Sri Rahayu ◽  
Netti Herawati ◽  
Mohammad Wijaya
Keyword(s):  
Catalytic Activity ◽  
Ethylene Glycol ◽  
Manganese Oxide ◽  
Sol Gel ◽  
Degradation Process ◽  
Oxide Nanoparticles ◽  
X Ray Diffraction ◽  
Manganese Oxide Nanoparticles ◽  
X Ray ◽  
Rhodamin B

Telah dilakukan penelitian tentang sintesis nanopartikel mangan oksida menggunakan prekursor KMnO4 dengan metode sol gel, dengan menambahkan aditif etilendiamin dan etilen glikol yang berperan sebagai agen penstabil, selanjutnya menguji aktivitas katalitik dari mangan oksida tersebut terhadap proses degradasi warna rhodamin B. Penelitian ini bertujuan untuk mengetahui pengaruh penambahan zat aditif terhadap ukuran dan bentuk nanopartikel yang dihasilkan serta kemampuannya sebagai katalis dalam proses degradasi zat warna rhodamin B. Nanopartikel yang diperoleh, dikarakterisasi menggunakan XRD (X-Ray Diffraction) dan SEM (Scanning Elektron Microscope) serta penentuan aktivitas katalitik dalam proses degradasi terhadap zat warna rhodamin B dengan spektrofotometer UV-Vis. Hasil penelitian menunjukkan sintesis nanopartikel menggunakan aditif etilendiamin lebih baik dibandingkan dengan aditif etilen glikol karena ukuran nanopartikel berkisar antara 5,66-33,38 dalam bentuk tetragonal. Morfologi nanopartikel mangan oksida terlihat berbentuk bulat yang seragam. Nanopartikel mangan oksida hasil sintesis mampu mempercepat proses degradasi warna rhodamin B dengan persentase degradasi mencapai 85,6%. Kata kunci: Nanopartikel, Mangan Oksida , Sol gel dan Rhodamin B ABSTRACT Research has been carried out on the synthesis of manganese oxide nanoparticles using KMnO4 precursors with the sol gel method, by adding ethylenediamine and ethylene glycol additives which act as stabilizing agents, then tested the catalytic activity of the manganese oxide on the degradation process of Rhodamine B. This study aims to determine the effect of adding substances additives on the size and shape of the nanoparticles were produced and their ability as catalysts in the degradation process of Rhodamin B. Nanoparticles were obtained, characterized using XRD (X-Ray Diffraction)and SEM (Scanning Elektron Microscope)and determination of catalytic activity in the degradation process of rhodamine B dyes with UV-Vis spectrophotometer. The results showed that the synthesis of nanoparticles using ethylenediamine additives was better than ethylene glycol additives because the size of the nanoparticles ranged from 5.66 to 33.38 in the tetragonal form. The morphology of manganese oxide nanoparticles looks uniform in shape. Manganese oxide nanoparticles can accelerate the degradation process of Rhodamin B with a percentage of degradation reaching 85.6%. Keywords: Nanoparticles, Manganese Oxide, Sol gel and Rhodamin B

scholarly journals Study of dielectric behavior and electrical properties of hematite α-Fe2O3 doped with Zn

2012 ◽  
Vol 44 (3) ◽  
pp. 307-321 ◽  
Author(s):  
M.V. Nikolic ◽  
M.P. Slankamenac ◽  
N. Nikolic ◽  
D.L. Sekulic ◽  
O.S. Aleksic ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Spinel Phase ◽  
Dielectric Behavior ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Range ◽  
Zn Content ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Two Phases

The effects of Zn-doping on the dielectric behavior and electrical properties of bulk ?-Fe2O3 have been studied. X-ray diffraction analysis revealed the presence of two phases in all samples: hematite and spinel ZnFe2O4, with the amount of spinel phase increasing with increasing Zn content. Scanning electron microscopy analysis combined with energy dispersive X-ray spectroscopy showed that the Zn-bearing phase occurred in the form of individual spinel ZnFe2O4 grains in a hematite matrix. DC conductivity was measured in the temperature range 25-225oC (298-498 K). Impedance spectroscopy measurements in the same temperature range were carried out in the frequency range 100Hz to 10 MHz. Increase in the Zn content resulted in increased electrical conductivity and higher values of the dielectric constant. The resistance and capacitance of grains and grain boundaries were analyzed by modeling the experimental results using an equivalent circuit.

The location of tantalum atoms in Ni3(Al, Ta)

1990 ◽  
Vol 5 (4) ◽  
pp. 763-768 ◽  
Author(s):  
Hui Lin ◽  
David P. Pope
Keyword(s):  
Long Range ◽  
Diffraction Method ◽  
Range Order ◽  
Average Particle ◽  
Particle Sizes ◽  
Long Range Order ◽  
X Ray ◽  
Fee Structure ◽  
Fine Powders ◽  
Superlattice Peak

An x-ray powder diffraction method was used to determine the location of tantalum atoms in Ni3Al. A series of Ni3(Al, Ta) alloys were produced with tantalum contents ranging from 0.1 to 3.0 at.%. Fine powders with average particle sizes less than 80 μm were made from melt-spun ribbons by a grinding process. The values of the intensity of the (100) superlattice peak normalized to that of the (200) fundamental peak as a function of tantalum content agreed with the calculated values, assuming that tantalum atoms substitute on aluminum sites, not on nickel sites, and also assuming small amounts of anti-site defects exist in the ordered fee structure of Ni3(Al, Ta) alloys. It is concluded from our experiments that tantalum atoms substitute for aluminum in Ni3Al. The long-range order parameters thus calculated of the Ni3(Al, Ta) alloys are generally above 0.84 and below 0.95, except for Ni75Al24.8Ta0.2, at which composition the long-range order parameter is close to unity.

scholarly journals In-flight Synthesis of Nanosized ZrC Particles from Various Precursors in RF Thermal Plasma

2021 ◽  
Author(s):  
Alejandro Martiz ◽  
Zoltán Károly ◽  
Eszter Bódis ◽  
Péter Fazekas ◽  
Miklós Mohai ◽  
...  
Keyword(s):  
Thermal Plasma ◽  
Photoelectron Spectroscopy ◽  
Average Particle Size ◽  
Reaction System ◽  
Spherical Shape ◽  
Molar Ratio ◽  
Average Particle ◽  
X Ray ◽  
Temperature Range ◽  
Rf Thermal Plasma

Synthesis of zirconium carbide (ZrC) powder was investigated applying a non-conventional atmospheric radiofrequency (RF) thermal plasma process. In one case, zirconium dioxide (ZrO2) was reacted with solid carbon or with methane with varying molar ratio. In the other, zirconium-propoxide (NZP), containing both constituents, was thermally decomposed in the Ar plasma. Temperature-dependent thermodynamic analysis was performed in the 500-5500 K temperature range to estimate the formation of possible equilibrium products for each reaction stoichiometry. Broad temperature range exists for the stability of solid ZrC for each explored reaction system. In accordance with this prediction, X-ray diffraction studies detected the ZrC as the major phase in all the prepared powders. The yield of particular runs ranged from 39 % to 98 %. Practically, full conversion was typical for the case of NZP precursor, however only partial conversion could be detected in ZrO2 reactions. The average particle size of the powders falls between 10 nm and 100 nm depending on the type of the reaction systems (either calculated from the specific surface area or derived from broadening the XRD reflections). The transmission electron micrographs indicated mostly globular shape of the nanosize particles. Quantitative analysis of the surface of the powders by X-ray photoelectron spectroscopy revealed the presence of oxygen and carbon. Evaluating the spectra of the powders prepared from NZP, and taking in the account its spherical shape, a ZrC core covered by a very thin (≈1.0 nm) ZrO2 layer may be accounted for the measured oxygen and a thicker carbonaceous layer.

Rapid Preparation of V2O3 and VN Nanocrystals by Ammonolysis of the Precursor VOC2O4•H2O

2011 ◽  
Vol 194-196 ◽  
pp. 660-664 ◽  
Author(s):  
Hua Lin ◽  
Bo Wan Tao ◽  
Qing Li ◽  
Yan Rong Li
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Average Particle ◽  
Particle Sizes ◽  
Tubular Furnace ◽  
Rapid Preparation ◽  
X Ray ◽  
Transmission Electron ◽  
Thermal Ammonolysis

V2O3 and VN nanocrystals have been conveniently synthesized from thermal ammonolysis of the precursor VOC2O4•H2O in a resistance tubular furnace at 500°С and 780°С for 30 min, respectively. The products were characterized by X-ray diffractometer (XRD)、X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) techniques. The average particle sizes of V2O3 and VN are both in the ranges of 20~35 nm. The evolution from precursor to hexagonal V2O3 and then to cubic VN was explored. The crucial factors，such as the reaction temperature and time，have also been discussed.

Influences of Progressing Parameters on Flake BaBi4Ti4O15 Powder Synthesized by Molten Salt Synthesis Method

2011 ◽  
Vol 335-336 ◽  
pp. 704-707 ◽  
Author(s):  
Jin Liang Huang ◽  
Li Hua Li ◽  
Yong Jun Gu ◽  
Qian Li
Keyword(s):  
Molten Salt ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Molten Salt Synthesis ◽  
Average Particle ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Chloride Flux ◽  
X Ray ◽  
Sulfate Flux

Abstract. BaBi4Ti4O15 powder was synthesized by molten salt synthesis (MSS) method in NaCl-KCl and Na2SO4-K2SO4 fluxes. The phases of reaction products and the microstructures at different calcined temperatures were detected by X-ray diffraction (XRD) and scanning electron microscope (SEM). As a result, the flaky BaBi4Ti4O15 powder with anisotropy was synthesized by molten salt synthesis method in NaCl-KCl and Na2SO4-K2SO4 fluxes in the range of 850～1050°C. Compared with BaBi4Ti4O15 powder synthesized in the sulfate flux, the anisotropy level of BaBi4Ti4O15 powder which was synthesized in chloride flux increased, the average particle size(APS) of BaBi4Ti4O15 powder synthesized in the chloride flux is slight larger than in the sulfate flux. The thickness of BaBi4Ti4O15 powder was synthesized by molten salt synthesis method in the chloride flux decreased than in the sulfate.

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