An investigation on the synthesis of nickel aluminate

2019 ◽  
Vol 48 (6) ◽  
pp. 487-492
Author(s):  
Liliya Frolova
Keyword(s):  
Electrical Conductivity ◽  
Single Phase ◽  
Molar Ratio ◽  
Precipitation Process ◽  
Complex Method ◽  
Nickel Aluminate ◽  
Content Type ◽  
Wide Range ◽  
Co Precipitation ◽  
Derivatographic Analysis

Purpose The purpose of this paper is to study the process of coprecipitation of polyhydroxocomplexes of nickel and aluminum from solutions of nickel (Ni) (II) sulfate and aluminum (Al) (III) sulfate with caustic soda and to study the conversion process to nickel aluminate and to check its properties. Design/methodology/approach For the thermodynamic analysis of the precipitation process, the software package MEDUSA was used. The dependences of the electrical conductivity, pH and residual concentrations as functions of the OH/Me ratio were obtained. Using X-ray phase analysis, spectroscopic analysis and derivatographic analysis, the properties of the products obtained were studied. The effects of OH/Me ratio and molar ratio cation of reagents on the physicochemical properties of the products were analyzed. Findings The paper deals with the results of theoretical and experimental research on the synthesis pigments of blue and green colors based on Ni-Al spinel. The influence of the molar ratio cation content on optical and color characterise of pigments were studied. Originality/value The original complex method of studying the processes of co-precipitation of cations in the form of hydroxides is proposed. pH precipitation of aluminum hydroxide and nickel are different. It is interesting to study their co-precipitation. The resulting single-phase product is a precursor of nickel aluminate over a wide range of cation ratios. The dependences of the electrical conductivity, pH and residual concentrations as functions of the OH/Me ratio were obtained.

scholarly journals Development of Radar Absorbing Nano Crystals under Thermal Irradiation

2008 ◽  
Vol 2 ◽  
pp. 91-104 ◽  
Author(s):  
Rahul Sharma ◽  
Ramesh Chandra Agarwala ◽  
Vijaya Agarwala
Keyword(s):  
Single Phase ◽  
Ostwald Ripening ◽  
Barium Hexaferrite ◽  
Uniform Structure ◽  
Precipitation Process ◽  
Vacuum Furnace ◽  
Morphological Transformation ◽  
Radar Absorbing Material ◽  
Wide Range ◽  
Co Precipitation

Single phase W-type barium hexaferrite nano crystals of radar absorbing material (RAM) i.e., BaMe2Fe16O27 (Me2+=Fe2+) were synthesized by a modified flux method that combines the controlled chemical co-precipitation process for nucleation and complete uniform growth during in-situ annealing with NaCl flux under vacuum furnace. Uniform structure morphological transformation of nano crystals from spherical to prism faces were noticed after annealing with increasing temperatures from 200 to 1200 oC for 4 h in vacuum. XRD results showed the single phase nanocrystals of BaFe18O27 with increasing crystallanity and size from 10 to 90 nm during annealing. FESEM and TEM were used to investigate the systematic growth processes of various morphologies of nano crystals. The effect of such systematic morphological transformation of nanocrystals was observed in dielectric, dynamic magnetic and refection loss (RL) properties in Kuband (12.4 -18.0 GHz). A significant increment from -15.23 dB to -43.65 dB with wide range of bandwidth in RL loss is noticed due to the symmetric morphological growth of single phase nano crystals of RAM during annealing. This process of crystal growth, morphology evolution and RL enhancement with respect to increasing temperature were also explained in terms of ostwald ripening and quantum size effect.

EFFECT OF NANOSIZED TiO2 POWDER ON PREPARATION AND PROPERTIES OF Ag-BASED ELECTRODE MATERIALS

2004 ◽  
Vol 03 (06) ◽  
pp. 829-837
Author(s):  
SOON-JONG JEONG ◽  
JUNG-HYUK KOH ◽  
DONG-YOON LEE ◽  
JAE-SEOK LEE ◽  
MUN-SU HA ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Bonding Strength ◽  
Electrode Materials ◽  
Precipitation Process ◽  
Nano Oxide ◽  
Diffusion Controlled ◽  
State Diffusion ◽  
Acid Reaction ◽  
Co Precipitation ◽  
Mechanical Bonding

This study presents the synthesis of nano-oxide-added Ag/Pd powders and its properties tolerable at temperatures above 1100°C for an electrode material utilized in multilayer ceramic devices. The powders of xAg/yPd powder around core cell TiO 2 were formed in a co-precipitation process of Ag and Pd in nano-oxide-dispersed solution, where Ag and Pd precursors are melted in HNO 3 acid. Reaction between ceramic and electrode layers with nanoparticle oxide powder allows internal stress to reduce and mechanical bonding strength to increase due to anchor effect. The densification of the nano-oxide-added electrode paste followed the TiO 2 solid state diffusion-controlled mechanism upon sintering process. The mechanical bonding strength and electrical conductivity were measured after sintering the electrode-printed sheets. As a result, very high adhesive strength over the piezoelectric ceramics' fracture strength and good electrical conductivity of more than 104/Ωcm could be obtained in the multilayer ferroelectric structure which is a form of stacking ceramics layer and electrode layer containing nanoparticles.

Structural, Thermal and Magnetic Analysis of Co2FeO4 Spinel Oxide Synthesized by Co-Precipitation Process

2014 ◽  
Vol 895 ◽  
pp. 287-290 ◽  
Author(s):  
Pradeep Reddy ◽  
Yesu Raja ◽  
M. Ashok
Keyword(s):  
Crystallite Size ◽  
Single Phase ◽  
Annealing Temperature ◽  
Precipitation Process ◽  
Spinel Oxide ◽  
Nano Powder ◽  
Magnetic Analysis ◽  
Phase Compound ◽  
Different Temperatures ◽  
Co Precipitation

Co2FeO4spinel oxide nano powder was synthesized by co-precipitation process. Samples were annealed at different temperatures of 500, 800 and 900oC and the phase purity were also analyzed. As-prepared sample has two spinel phases and on annealing at 900οC single phase compound formed. The crystallite size of as-prepared is found to be 11.9 nm. The crystallite size increased with increase in annealing temperature to a maximum of 17.4 nm for 900 °C. Samples were subjected to necessary characterization for finding thermal, magnetic and optical band gap.

The Effect of Preparation Method of Precursor on Synthesis of BiFeO3 by a Hydrothermal Method

2014 ◽  
Vol 906 ◽  
pp. 178-182
Author(s):  
Yang Xiao ◽  
Zhen Zhu Cao ◽  
Ru Yi Shao ◽  
Wei Yan He ◽  
Yan Fang Gao ◽  
...  
Keyword(s):  
Reaction Time ◽  
Hydrothermal Method ◽  
Influencing Factors ◽  
Preparation Method ◽  
Raw Materials ◽  
Bismuth Ferrite ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Precipitation Process ◽  
Co Precipitation

The precursor of bismuth ferrite BiFeO3 powders were prepared by the normal co-precipitation and reversed co-precipitation method. The key influencing factors including the reaction time, the concentration of mineralizer and the molar ratio of raw materials in the normal co-precipitation are systematically studied. Pure BiFeO3 powder has been obtained by adjusting the molar ratio of raw materials. Based on the results of the normal co-precipitation, a simple reversed co-precipitation process has been developed.

The wide range of output frequency regulation method for the inverter using the combination of PWM and DDS

2019 ◽  
Vol 38 (4) ◽  
pp. 1323-1333 ◽  
Author(s):  
Wojciech Pietrowski ◽  
Wojciech Ludowicz ◽  
Rafal Marek Wojciechowski
Keyword(s):  
Single Phase ◽  
Pulse Width Modulation ◽  
Harmonic Distortion ◽  
Low Frequency ◽  
Modulation Method ◽  
Frequency Regulation ◽  
Content Type ◽  
Output Waveform ◽  
Wide Range ◽  
Single Phase Inverter

Purpose The specific modulation methods are used to control different kind of single-phase, as well as three-phase, inverters to ensure flexibility and high quality of the output waveform. This paper aims to present a combination of two classical methods, namely, pulse width modulation method and direct digital synthesis modulation method. Design/methodology/approach The total harmonic distortion of output waveforms of single-phase inverter based on elaborated modulation method has been determined by means of fast Fourier transform analysis. Tests have been carried out by using standard low-frequency application and also a wireless resonant energy link system. Findings Applying appropriate timer parameters of microcontroller enables to obtain a waveform for given output parameters (amplitude, frequency, frequency modulation index, etc.). The only limitation is the computing power of a microcontroller. Originality/value The elaborated method can be successfully used in both low- and high-frequency application ensuring high level of output waveform quality. Additional signal generators and the control of amplitude modulation ratio are no longer indispensable, what simplify immensely a control system.

scholarly journals Preparation and characterization of iron-copper binary oxide and its effective removal of antimony(III) from aqueous solution

2016 ◽  
Vol 74 (2) ◽  
pp. 393-401 ◽  
Author(s):  
Yongchao Li ◽  
Bing Geng ◽  
Xiaoxian Hu ◽  
Bozhi Ren ◽  
Andrew S. Hursthouse
Keyword(s):  
Aqueous Solution ◽  
Photoelectron Spectroscopy ◽  
Binary Oxide ◽  
Molar Ratio ◽  
Precipitation Process ◽  
Maximum Adsorption Capacity ◽  
Solution Ph ◽  
X Ray ◽  
Freundlich Adsorption Isotherm ◽  
Co Precipitation

An Fe-Cu binary oxide was fabricated through a simple co-precipitation process, and was used to remove Sb(III) from aqueous solution. X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and N2 adsorption–desorption measurements demonstrated that the Fe-Cu binary oxide consisted of poorly ordered ferrihydrite and CuO, and its specific surface area was higher than both iron oxide and copper oxide. A comparative test indicated that Fe/Cu molar ratio of prepared binary oxide greatly influenced Sb(III) removal and the optimum Fe/Cu molar ratio was about 3/1. Moreover, a maximum adsorption capacity of 209.23 mg Sb(III)/g Fe-Cu binary oxide at pH 5.0 was obtained. The removal of Sb(III) by Fe-Cu binary oxide followed the Freundlich adsorption isotherm and the pseudo-second-order kinetics in the batch study. The removal of Sb(III) was not sensitive to solution pH. In addition, the release of Fe and Cu ions to water was very low when the pH was greater than 6.0. X-ray photoelectron spectroscopy analysis confirmed that the Sb(III) adsorbed on the surface was not oxidized to Sb(V).

Systematic Precipitation of Magnesium Hydroxide Using NH4OH to Preparing MgO-PSZ Precursor Powder

2014 ◽  
Vol 805 ◽  
pp. 712-717
Author(s):  
Chieko Yamagata ◽  
Jose O.A. Paschoal
Keyword(s):  
Magnesium Hydroxide ◽  
Room Temperature ◽  
Low Cost ◽  
Zirconium Oxychloride ◽  
Precursor Powder ◽  
Molar Ratio ◽  
Ceramic Processing ◽  
Wide Range ◽  
High Molar Ratio ◽  
Co Precipitation

The wide range of applications of zirconia based ceramics is due to stabilization of its tetragonal and cubic structures at room temperature, by controlled adding of dopants such as yttria, magnesia, calcia, ceria and some rare earth oxides. The advantage of the use of magnesia as dopant is not only due to its low cost, but fact that by controlling its ceramic processing, it is possible to control a specific microstructure for the specific application. The precipitation of magnesium hydroxides, using NH4OH as a precipitant, presents some difficulties due to the formation of a variety of soluble complexes of ammonia with magnesium, which inhibits the total precipitation of magnesium. In the present work, the influence of precipitant and metals concentrations and pH on the magnesium hydroxide precipitation was investigated. Magnesium chloride, zirconium oxychloride and NH4OH were used as starting materials. The precipitation of magnesium hydroxide depends on concentrations of OH-, Cl- and Mg2+. To achieve specific precipitation yield, lower the concentration of Mg2+ high molar ratio of [OH-]/[Cl-] is required. The pH measure is not enough to control Mg (OH)2 precipitation. The use of molar ratio of [OH-]/[Cl-] = 4.4, resulted in 95 % of Mg (OH)2 precipitation. The co-precipitation of Zr and Mg hydroxides, using the optimized molar ratio of [OH-]/[Cl-], the precipitation of Mg (OH)2 achieved in range of 97.6 to 98.3 %.

Synthesis and Properties of Superparamagnetic Fe3O4 Nanoparticles by Co-Precipitation Process

2013 ◽  
Vol 377 ◽  
pp. 173-179 ◽  
Author(s):  
Chan Yin ◽  
Xiao Yi Wei ◽  
Ji Hua Li ◽  
Fei Wang
Keyword(s):  
Particle Size ◽  
Saturation Magnetization ◽  
Single Phase ◽  
Average Particle Size ◽  
Particle Surface ◽  
Anhydrous Ethanol ◽  
Precipitation Process ◽  
Average Particle ◽  
Agglomeration Of Nanoparticles ◽  
Co Precipitation

Superparamagnetic Fe3O4nanoparticle with single phase has been synthesized successfully by a co-precipitation process. On the other hand, the effect of additive anhydrous ethanol in synthesis procedure was investigated for the magnetic properties of nanoparticles in this paper. The structure properties of synthetic Fe3O4particle were measured through XRD, FT-IR and TG-DSC devices. The characteristic peaks of Fe3O4have been observed to testify Fe3O4with single phase. The particle size and shape were observed by SEM and TEM measurements. The addition of anhydrous ethanol could enhance the dispersion of Fe3O4nanoparticles and restrain the agglomeration of nanoparticles. Therefore, the average particle size was about 18.2 nm, smaller than that of Fe3O4particles prepared without anhydrous ethanol of 24.3 nm. Correspondingly, the saturation magnetization (Ms) of Fe3O4prepared with and without anhydrous ethanol was determined to be 53.28 emu/g and 65.28 emu/g, respectively, lower than bulk magnetite particles of 90 emu/g. That is because, synthetic Fe3O4with smaller particle size obtains the higher surface curvature, which could enhance the disordered crystal orientation on the particle surface, so the saturation magnetization was decreased.

Electrical Conductivity of Ionic and Electronic Mixture

2001 ◽  
Vol 699 ◽  
Author(s):  
Gyeong Man Choi ◽  
Joon Hee Kim ◽  
Young Min Park
Keyword(s):  
Electrical Conductivity ◽  
Single Phase ◽  
Electronic Conductivity ◽  
Charge Carriers ◽  
Electronic Charge ◽  
Total Conductivity ◽  
Mixed Conductivity ◽  
Emf Measurements ◽  
Wide Range ◽  
Mixed Ionic Electronic Conductors

AbstractMixed ionic-electronic conductors (MIECs) which have both ionic and electronic species as charge carriers have a wide range of applications, such as electrodes in fuel cells, electrocatalytic reactors, and gas separating membranes. They may have either electronic or ionic species as the majority charge carriers. In addition to the single-phase mixed conductors, they may be fabricated by mixing two different phases of materials. Although these composites have been less studied than the single phase MIECs, the combined properties are often superior to single phase MIECs, and properties not seen in an individual phase may appear in the composite phase.YSZ-based composite systems were chosen to test the effect of transition-metal-oxide (TMO) addition on the electronic conductivity of composite. To induce mixed conductivity, electronic-conducting TMOs such as NiO and Mn2O3 were added into YSZ above the solubility limit. While the solid solubility of NiO in YSZ is limited that of Mn2O3 is large.In this work, mixed conducting yttria (8 mol%) stabilized zirconia (YSZ) - TMO composites were prepared in full composition range and the electrical conductivity of the composites was measured by 4-probe d.c. conductivity. Electromotive force (emf) measurements of the galvanic cell, current-voltage (I-V) measurements in ion blocking condition and the oxygen-partial-pressure dependent conductivity have been used to determine the contribution of the ionic and electronic charge carriers on the conductivity. Thus the composition-dependent electrical properties were used to explain the percolation behavior of electronic charge carriers in ionic matrix.Although the total conductivity of dense YSZ-TMO composite was variable with TMO content, the partial-electronic conductivity increased and the ionic conductivity decreased. The composition-dependent conductivity was discussed.

Effect of MCl (M = Na, K) addition on microstructure and electrical conductivity of forsterite

2020 ◽  
Vol 92 (1) ◽  
pp. 10901
Author(s):  
Saloua El Asri ◽  
Hamid Ahamdane ◽  
Lahoucine Hajji ◽  
Mohamed El Hadri ◽  
Moulay Ahmed El Idrissi Raghni ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electrical Conductivity ◽  
Single Phase ◽  
Sol Gel ◽  
Complex Impedance ◽  
Transmission Spectra ◽  
Electrical Measurements ◽  
Cation Type ◽  
Edx Analyses ◽  
The Fourier Transform

Forsterite single phase powder Mg2SiO4 was synthesized by sol–gel method alongside with heat treatment, using two different cation alkaline salts MCl as mineralizers (M = Na, K) with various mass percentages (2.5, 5, 7.5, and 10 wt.%). In this work, we report on the effect of the cation type and the added amount of used mineralizer on microstructure and electrical conductivity of Mg2SiO4. The formation of forsterite started at 680–740  °C and at 630–700  °C with KCl and NaCl respectively, as shown by TG-DTA and confirmed by XRD. Furthermore, the Fourier transform infrared (FTIR) transmission spectra indicated bands corresponding to vibrations of forsterite structure. The morphology and elemental composition of sintered ceramics were examined by SEM-EDX analyses, while their densities, which were measured by Archimedes method, increased with addition of both alkaline salts. The electrical measurements were performed by Complex Impedance Spectroscopy. The results showed that electrical conductivity increased with the addition of both mineralizers, which was higher for samples prepared with NaCl than those prepared with KCl.

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