Structure and properties of nanocrystalline nickel prepared by selective leaching at different temperatures

2017 ◽  
Vol 89 (4) ◽  
pp. 545-552
Author(s):  
Alena Michalcová ◽  
Ivo Marek ◽  
Adél Len ◽  
Oleg Heczko ◽  
Jan Drahokoupil ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Water Solution ◽  
Structure And Properties ◽  
Selective Leaching ◽  
Nanocrystalline Nickel ◽  
Micro Particles ◽  
Nickel Particles ◽  
Nanocrystalline Particles ◽  
Different Temperatures

Abstract Nanocrystalline nickel is an interesting material for catalysis, and also, like all nanocrystalline metals, it has potential for structural application. Our aim was to develop a method for preparation of precursor materials for powder metallurgy. Because of this, selective leaching of binary alloy was chosen as it leads to production of nanocrystalline clustered (sub)micro particles. In this work, the preparation of Ni particles by selective leaching of Al matrix from Al-50 wt.% Ni in NaOH water solution is described. It was found that structure and magnetic properties were strongly dependent on leaching temperature, which was proven by characterization of Ni particles leached at −20, 0, 20, 40, 60 and 80°C. The microstructure of as-prepared particles was observed by HRTEM and also by small angle neutron scattering. Magnetic properties were characterized by measuring of saturation magnetization. It was proven that with increased leaching temperature the grain size of prepared nanocrystalline particles increased. Also the value of saturated magnetization follows the same trend. The amount of hydrogen stored in nickel particles is independent on leaching temperature.

scholarly journals Extraction and Characterization of Galactan from Seaweed Gracilaria verrucosa of Vietnam 

2021 ◽  
Vol 31 (1) ◽  
pp. 73-77
Keyword(s):  
Differential Scanning Calorimetry ◽  
Infrared Spectroscopy ◽  
Thermal Resistance ◽  
Gracilaria Verrucosa ◽  
Structure And Properties ◽  
Scanning Calorimetry ◽  
Different Temperatures ◽  
Kjeldahl Method ◽  
Viscosity Determination

In this study, we extracted galactan from the seaweed Gracilaria verrucosa of Vietnam and investigated its structure and properties. The seaweed was immersed in water in the different temperatures to obtain the solution of galactan. Thereafter, the solution was coagulated and purified to obtain galactan as a powder. Kjeldahl method, infrared spectroscopy, viscosity determination and differential scanning calorimetry (DSC) were used to characterize structure and properties of the resulting material. It was found that the obtained galactan had agar structure without sulfate as substitute group. The proteins content, the intrinsic viscosity and the thermal resistance of the galactan extracted in water at 40 oC were higher than those of the galactan extracted in water at 100 oC.

AEM analysis of crystallization in Ti-based amorphous alloys

1983 ◽  
Vol 41 ◽  
pp. 270-271
Author(s):  
A.R. Pelton ◽  
A.F. Marshall ◽  
Y.S. Lee
Keyword(s):  
Magnetic Properties ◽  
Amorphous Alloys ◽  
Amorphous Materials ◽  
Isothermal Annealing ◽  
Amorphous Matrix ◽  
Nucleation And Growth ◽  
Current Interest ◽  
Amorphous Films ◽  
Electrical And Magnetic Properties

Amorphous materials are of current interest due to their desirable mechanical, electrical and magnetic properties. Furthermore, crystallizing amorphous alloys provides an avenue for discerning sequential and competitive phases thus allowing access to otherwise inaccessible crystalline structures. Previous studies have shown the benefits of using AEM to determine crystal structures and compositions of partially crystallized alloys. The present paper will discuss the AEM characterization of crystallized Cu-Ti and Ni-Ti amorphous films.Cu60Ti40: The amorphous alloy Cu60Ti40, when continuously heated, forms a simple intermediate, macrocrystalline phase which then transforms to the ordered, equilibrium Cu3Ti2 phase. However, contrary to what one would expect from kinetic considerations, isothermal annealing below the isochronal crystallization temperature results in direct nucleation and growth of Cu3Ti2 from the amorphous matrix.

Synthesis and Characterization of Nanocrystalline ZnO Powders by a Direct Thermal Decomposition Route Using Zinc Nitrate Hexahydrate

2013 ◽  
Vol 770 ◽  
pp. 68-71 ◽  
Author(s):  
Supphadate Sujinnapram ◽  
Uraiphorn Termsuk ◽  
Atcharawan Charoentam ◽  
Sutthipoj Sutthana
Keyword(s):  
Thermal Decomposition ◽  
Crystallization Temperature ◽  
Zinc Nitrate ◽  
Zinc Nitrate Hexahydrate ◽  
Absorption Peak ◽  
Synthesis And Characterization ◽  
Nitrate Hexahydrate ◽  
Different Temperatures ◽  
Zno Powders

The nanocrystalline ZnO powders were synthesized by a direct thermal decomposition using zinc nitrate hexahydrate as starting materials. The precursor was characterized by TG-DTA to determine the thermal decomposition and crystallization temperature which was found to be at 325 oC. The precursors were calcined at different temperatures of 400, 500, and 600°C for 4 h. The structure of the prepared samples was studied by XRD, confirming the formation of wurtzite structure. The synthesized powders exhibited the UV absorption below 400 nm (3.10 eV) with a well defined absorption peak at around 285 nm (4.35 eV). The estimated direct bandgaps were obtained to be 3.19, 3.16, and 3.14 eV for the ZnO samples thermally decomposed at 400, 500, and 600°C, respectively.

scholarly journals Influence of Cu on the Improvement of Magnetic Properties and Structure of L10 FePt Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1097
Author(s):  
Luran Zhang ◽  
Xinchen Du ◽  
Hongjie Lu ◽  
Dandan Gao ◽  
Huan Liu ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Annealing Temperature ◽  
Reduction Method ◽  
Solid Phase ◽  
Average Particle Size ◽  
Fept Nanoparticles ◽  
Average Particle ◽  
Phase Reduction ◽  
Different Temperatures ◽  
One Step

L10 ordered FePt and FePtCu nanoparticles (NPs) with a good dispersion were successfully fabricated by a simple, green, one-step solid-phase reduction method. Fe (acac)3, Pt (acac)2, and CuO as the precursors were dispersed in NaCl and annealed at different temperatures with an H2-containing atmosphere. As the annealing temperature increased, the chemical order parameter (S), average particle size (D), coercivity (Hc), and saturation magnetization (Ms) of FePt and FePtCu NPs increased and the size distribution range of the particles became wider. The ordered degree, D, Hc, and Ms of FePt NPs were greatly improved by adding 5% Cu. The highest S, D, Hc, and Ms were obtained when FePtCu NPs annealed at 750 °C, which were 0.91, 4.87 nm, 12,200 Oe, and 23.38 emu/g, respectively. The structure and magnetic properties of FePt and FePtCu NPs at different annealing temperatures were investigated and the formation mechanism of FePt and FePtCu NPs were discussed in detail.

Optimizing the magnetic properties of Fe-based amorphous powder by adjusting atomic structures from vitrification at different temperatures

2019 ◽  
Vol 126 (16) ◽  
pp. 165109
Author(s):  
Song-Yi Kim ◽  
Hye-Ryeong Oh ◽  
Hyeon-Ah Kim ◽  
A-Young Lee ◽  
Hwi-Jun Kim ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Amorphous Powder ◽  
Atomic Structures ◽  
Different Temperatures

scholarly journals Green synthesis and characterization of hexaferrite strontium-perovskite strontium photocatalyst nanocomposites

2020 ◽  
Vol 43 (1) ◽  
pp. 26-42 ◽  
Author(s):  
Zahra Hajian Karahroudi ◽  
Kambiz Hedayati ◽  
Mojtaba Goodarzi
Keyword(s):  
Magnetic Properties ◽  
Green Synthesis ◽  
Sol Gel ◽  
Synthesis Method ◽  
Combustion Method ◽  
Lemon Juice ◽  
X Ray Diffraction ◽  
X Ray ◽  
Auto Combustion

AbstractThis study presents a preparation of SrFe12O19– SrTiO3 nanocomposite synthesis via the green auto-combustion method. At first, SrFe12O19 nanoparticles were synthesized as a core and then, SrTiO3 nanoparticles were prepared as a shell for it to manufacture SrFe12O19–SrTiO3 nanocomposite. A novel sol-gel auto-combustion green synthesis method has been used with lemon juice as a capping agent. The prepared SrFe12O19–SrTiO3 nanocomposites were characterized by using several techniques to characterize their structural, morphological and magnetic properties. The crystal structures of the nanocomposite were investigated via X-ray diffraction (XRD). The morphology of SrFe12O19– SrTiO3 nanocomposite was studied by using a scanning electron microscope (SEM). The elemental composition of the materials was analyzed by an energy-dispersive X-ray (EDX). Magnetic properties and hysteresis loop of nanopowder were characterized via vibrating sample magnetometer (VSM) in the room temperature. Fourier transform infrared spectroscopy (FTIR) spectra of the samples showed the molecular bands of nanoparticles. Also, the photocatalytic behavior of nanocomposites has been checked by the degradation of azo dyes under irradiation of ultraviolet light.

Synthesis and characterization of layered bismuth vanadates

1990 ◽  
Vol 5 (11) ◽  
pp. 2718-2722 ◽  
Author(s):  
K. B. R. Varma ◽  
G. N. Subbanna ◽  
T. N. Guru ◽  
C. N. R. Rao
Keyword(s):  
Curie Temperature ◽  
General Formula ◽  
Layered Structure ◽  
Synthesis And Characterization ◽  
Structure And Properties ◽  
Bismuth Vanadates

Bi2VO5.5 (Bi4O11), which is the vanadium analog of the first member of the Aurivillius family of oxides of the general formula Bi2An−1BnO3n+3, has been prepared and characterized. The vanadate has the expected layered structure and is ferroelectric with a Curie temperature of 720 K. While we have not been able to synthesize the vanadium analog of the n = 2 member of the Aurivillius family, we have examined the structure and properties of a vanadate of the composition Bi2V3O9.

Sign in / Sign up

Export Citation Format

Share Document