Ceramic Nanopowders Research Articles

Nanoceramic NiMn2O4 Powder-Based Resistance Thermometer for Soil Temperature Measurement Application

The objective of this study is to construct a thermometer for soil temperature measurement application using sol-gel derived nanoceramic NiMn2O4 powder. The nanoceramic NiMn2O4 powder has been prepared using wet chemical method and characterized by FESEM/EDS and XRD. FESEM results confirmed its uniform morphology and the formation of the nanopowder. EDS confirmed that the powder consists of Ni, Mn, and O2. Based on the XRD analysis results and Scherrer’s formula the average crystallite size became 34nm. The powder then compressed in electrically insulator but thermally conductor tube manually to make the thermistor based thermometer. Two pieces of folded and rolled Aluminum foils as electrical contacts followed by two Aluminum lead wires were connected to the two opposite terminals of the tube. The thermometer is calibrated and characterized using LM35 IC temperature sensor integrated with Arduino Atmega328. The thermometer can measure a soil temperature up to 42℃. The embedded system for the thermometer is done using Arduino microcontroller and Arduino software with signal conditioning circuits. This is the first kind of thermometer which is based on nanomaterials for soil temperature measurement application in Agriculture. Keywords: NiMn2O4; nanoceramic powder; thermometer; thermistor; soil temperature; calibration Figure 1

Structural changes and magnetism in Bi1−xBa x FeO3 (x = 0, 0.1, 0.2, 0.3) nanopowders

Bi1−xBa x FeO3 (x = 0, 0.1, 0.2 and 0.3) ceramic nanopowders were prepared by the ethylene glycol-based sol–gel method followed by heat treatment at 800 °C for 1 h. The effect of Ba2+ ions substitution on the structural and magnetic properties of the BiFeO3 (BFO) has been investigated. X-ray diffraction along with Rietveld refinement of Ba-substituted samples showed the presence of both rhombohedral (R3c) and pseudocubic (Pm3m) phases. Microstructural analysis confirmed the formation of homogeneous and nearly cubic nanoparticles. Result shows a reasonable enhancement in saturation magnetization of the substituted samples. Bi0.9Ba0.1FeO3 having 30% R3c and 70% Pm3m phases, show maximum saturation magnetization, i.e., 0.32 emu/g at room temperature. The magnetic properties of synthesized ceramics have been discussed in terms of FeO6 octahedra tilting with respect to body diagonal of the pseudocubic system. By combining magnetic measurements with thermal analysis, it is shown that the substitution of Ba for Bi site causes an enhancement in magnetic transition temperature (TN).

Evaluation of La0.6Sr0.4Co0.2Fe0.8O3-δ as a potential cathode for proton-conducting solid oxide fuel cell

The application of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) as a potential cathode working on a BaCe0.54Zr0.36Y0.1O2.95 (BCZY) electrolyte for proton conducting solid oxide fuel cell was investigated. LSCF nanoceramic powders were synthesized by an activated carbon-assisted sol-gel process using metal nitrate-based chemicals. The LSCF powder was transformed to a slurry and spin-coated onto both surfaces of BCZY pellet to form a symmetrical cell with the configuration of LSCF|BCZY|LSCF. The symmetrical cell was subsequently sintered at 950°C for 2 h to allow a good contact formation between electrode/ electrolyte layers. The phase structural verification of the calcined powders was investigated by X-Ray diffractometer (XRD). Field-emission scanning electron microscopy (FESEM) was employed to examine the morphology of the sintered cell. The electrochemical behaviour of the symmetrical cell was studied by an electrochemical impedance spectroscopy. The formation of a single perovskite LSCF phase with a crystallite size of 20 nm was obtained at 700°C as corroborated by XRD analysis. The FESEM images showed a good contact between LSCF cathode and BCZY electrolyte at electrode/ electrolyte interfacial layer. The ASR obtained for LSCF symmetrical cell measured at 700°C with and without Pt current collector is 0.87 and 31.25 Ωcm2, respectively.

Experimental Characterization of Meso-Micro Fractals from Nanoparticle Seeded Resin in Lifting Plate Hele-Shaw Cell

Various processes are developed to fabricate meso and micro size fractal structures for wide variety of engineering applications. Various types of fluid flows are studied and are deployed to develop meso and micro fractal structures. Lift Plate Hele-Shaw fluid flow also termed as Saffman-Taylor instability is one of the fluid phenomenon’s which can be easily used to fabricate such structures. In this process, fractals are formed by capturing the fluid droplet between thin gaps of two flat parallel plates and moving the upper plate in controlled manner. The formation of the fractal depends on process parameters; viz velocity of plate, fluid property and gap between the plates. This paper presents the exhaustive characterization of fluid composed of photopolymer seeded with the nanopowder in lifting plate Hele-Shaw cell. The prepared resin is mixture of monomer Hexanediol Diacrylate (HDDA) and photoinitiator Benzoyl Ethyl Ether (BEE) seeded with ceramic nanopowder. The fractal growth is observed from the prepared resin under lifting plate Hele Shaw cell through designed of experiments. The parameters; fluid separation velocity and gap between the plates are varied through developed system and effect of viscosity is observed by varying the loading of the ceramic nanopowder. The exhaustive characterization of the process has presented the effect of parameters and its interactions on the formation of the fractal. Further the fractal growth is presented in the dimensionless manner for its generalization. The experimental characterization has given a generalised methodology for the formation of controlled fractals or to mimic various meso and micro fractals available in the nature.

New Soft Magnetic Material Bonding Approach Using Ceramic Precursors and Ceramic Nanopowder

In this paper, we propose a new metal bonding method using a ceramic precursor (zirconium butoxide or titanium tetraisopropoxide) or a ceramic nano powder. Magnetic hysteresis curves of the bonded specimen did not change significantly after bonding in terms of the maximum magnetic field strength, the coercive force, and the residual magnetization. Iron loss of the specimen bonded using titanium tetraisopropoxide at 50 Hz increased by just 2.5%. The maximum shear strength per unit area was 0.29 N/mm2.

Performance of nanoceramic powder on the chemical and physical properties of bitumen

Approximately 30% of industrially produced ceramic materials worldwide are dumped as waste in landfills. Thus, these materials are a major environmental concern. Reusing or recycling these ceramic wastes for constructive purposes remains challenging. In this work, we evaluated for the first time the modified chemical and physical properties of bitumen incorporated with inorganic nanoceramic powder (NCP) produced from the ceramic wastes. Chemical and morphological properties of bitumen with NCP were determined. Bitumen specimens were characterized using transmission electron microscopy, X-ray fluorescence spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and atomic force microscopy (AFM). Physical and rheological properties of the specimens were also examined by penetration, softening point, and dynamic shear rheometer tests. Morphological analysis revealed the formation of an interaction between the SiOSi stretching vibration and hydrocarbon molecules. This interaction resulted from the incorporation of NCP into the unmodified bitumen matrix. The interaction increased the viscosity and reassembled the asphaltene particles. Thus, a new asphaltene sheet was generated, and the aromatic bonds (CC) were strengthened. AFM results reaffirmed the structural improvement of bitumen. Furthermore, the elasticity of bitumen and viscoelasticity of its matrix increased. These improvements can be attributed to the formation of the polyaromatic structure.

Synthesis of Nb2O5 and Ta2O5 nanopowders by means of an endo-templating method

Finding efficient templates for the nanostructuring of materials is a key point. Here, the niobium (V) - and tantalum (V) oxide ceramics nanopowders have been synthesized by a hard-templating approach by using the tricalcium phosphate biomaterial (Ca3(PO4)2.xH2O) as template agent. The oxide ceramics were investigated by X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, nitrogen physisorption and Scanning Electron Microscopy (SEM). It was observed that the surface properties (specific surface areas, pore volumes) of the Nb2O5 and Ta2O5 powders were strongly dependent of the amount of the Ca3(PO4)2.xH2O template previously used in the preparation of the [oxide ceramics/template] composites. For instance, with a Ca3(PO4)2.xH2O/ceramic salt weight ratio ranging from 0 to 1, the specific surface areas of Nb2O5 and Ta2O5 were gradually enhanced of 48–166m2/g and 5–84m2/g, respectively. The pore volumes were increased as well. The use of the eco-friendly tricalcium phosphate material (Ca3(PO4)2.xH2O) as template in the hard-templating approach may be suitable and efficient in the aim of synthesizing materials with enhanced surface properties.

Drawability and size effects for micro-arrayed deep drawing of Ni-Co/GO nanocomposite foils

For the first time, three different male dies (a rigid male die, an aluminum male die, and a nanoceramic powder male die) are used for a micro-arrayed deep drawing process using graphene oxide (GO) reinforced Ni-Co nanocomposite. Micro-parts with different shapes can be formed using the different male dies, and models to predict crack positions are established. The nanocomposite size effect leads to an increased depth-diameter ratio for decreasing female die diameters, and the conservation of volume leads to higher depth-diameter ratios and thinning rates. The reinforcing GO phase not only is able to improve the micro formability of the composite, but also inhibits grain growth at high temperature.

(Invited) Ion-Transport in Polymer-in-Ceramic Electrolytes

Solid electrolytes could revolutionize battery and supercapacitor technology because of their nontoxicity, stability during operation and enhanced safety. The major limitation of solid electrolytes is their low ionic conductivity at room temperature, and intricate ion transport complicated by grain-boundary phenomena. We have developed, and present here, novel polymer-in-ceramic composite electrolytes with high ion-conduction properties, prepared by electrophoretic deposition. Nanoparticles of LiAlO2, Li10SnP2S12, and some ion-conducting glasses were used as ceramic matrices. Polyethyleneimine (PEI) and polyethylene oxide (PEO) were tested as binders and lithium-ion-conducting media. Our recently developed simplified Poisson-Boltzmann model reveals that the adsorption of PEI on the surface of ceramic particles increases zeta potential, repulsion forces between the particles and their deposition rate. The electrophoretic deposition of PEO and nanoceramic powders occurs from the individual entities. We have succeeded in depositing films containing 5 to 40% PEO which are homogeneous in composition and uniform in thickness. XRD and DSC tests showed that the crystallinity of the polymer confined in the pores of ceramics, is suppressed. This was expected to improve the ionic conductivity of composite electrolytes saturated with LiI salt. However, on the basis of AC-impedance, NMR and high-resolution X-ray tomography data, we suggest that the high ionic conductivity (0.5mS/cm) at room temperature and low activation energy (2.3kJ/mole) are brought about by the grain-boundaries current path between the excess of LiI and ceramic nanoparticles, and not by the confined-in-ceramic polymer. The nanoarchitecturing of ordered, fast-ion-conduction paths and the elimination of perpendicular blocking grain boundaries is expected to reduce the effect of high-resistant grains.

Modeling the size distribution in a fluidized bed of nanopowder

The release of nanosized particles from fluidized beds of ceramic oxide nanopowders, namely, TiO2 (P25), Al2O3 (AluC) and SiO2 (A130) has been assessed for the first time.

Zirconia nano-powder – a useful precursor to dense polycrystals

The main problem of utilization of ceramic nanopowders consists in their tendency to form hard agglomerates. The inter-agglomerate space forms pores surrounded by numerous elementary particles (crystallites). Such pores cannot be easily removed from the system during pressureless sintering. So, the obvious strategy for a technologist is to eliminate such pores at the level of shaping operations. Dry pressing is a frequently applied shaping technique of ceramic materials. That is why mechanical strength of agglomerates should be as low as possible. It enables the elimination of inter-agglomerate pores to occur under moderate pressures, applied during the shaping process. This problem will be illustrated using the really nanometric (below 10nm) zirconia-yttria solid solution powder. The methods of effecting agglomerate strength will be shown. One of the elaborated powder preparation rout results in extremely soft agglomerates.

A study on the synthesis and magnetic properties of the cerium ferrite ceramic

This work is a short report on the synthesis of CeFeO3 ceramic nanopowder from a mixture of CeO2 and Fe2O3 powders via a high energy ball milling process and subsequent heat treatment. Investigation of the magnetic, photocatalytic and absorption properties of CeFeO3 and its potential for colossal dielectric constant (CDC) are the main objectives of the present study. The characterization tools were X-ray diffraction (XRD), transmission electron microscopy (TEM), Field emission scanning electron microscopy (FESEM), thermogravimetry (TG), differential thermal analysis (DTA), X-ray photoemission spectroscopy (XPS), ultraviolet–visible spectroscopy (UV–vis) and Image-J software. According to the obtained results, CeFeO3 nanopowder can be raised as a visible light-driven photocatalyst, a semiconductor material with a narrow bandgap and a weak ferromagnetic material. For the first time the CDC behavior of this ceramic was also assessed by XPS analysis which was indicative of a good colossal dielectric constant. The results were also confirmed by the measured dielectric properties.

Synthesis and Electrophysical Properties of Ceramic Nanocomposites Based on Potassium Polytitanate Modified by Chromium Compounds

The thermal behavior of potassium polytitanate modified in a water solution of CrCl3 in 4 and 18 h and characterized by different degree of uniformity of the chromium distribution in the particles is investigated. It is shown that even though the powder precursors have close chemical compositions their heat treatment (at 850°C for 2 h) leads to the formation of ceramic nanopowders with different phase compositions. It is shown by means of impedance spectroscopy that the product obtained on the basis the precursor powder with lower uniformity of the chromium distribution has much higher permittivity.

Microwave Assisted Preparation of YAG and Yb:YAG Transparent Ceramic Nanopowders for Laser Crystal

YAG and Yb:YAG transparent ceramic nanopowders for laser crystal were synthesized by microwave-assisted alkoxide hydrolysis precipitation method. The YAG and Yb:YAG nanopowders were characterized by differential thermal analysis and thermo gravimetric analysis (DTA-TG), infrared spectrum (IR), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and photoluminescence (PL) spectrum. The results show that the crystallizing temperature of the precursor of YAG and Yb:YAG is about 930 °C. The pure phase YAG and Yb:YAG nanopowders can be obtained at microwave radiation power of 385 W, microwave radiation time of 30 min and sintering temperature of 1100 °C. The average particle size of YAG is about 120 nm. Yb:YAG is uniform sphere and the average sizes is about 100 nm. The intensity of luminescence of Yb:YAG nanopowders decreased with the increasing of microware time. The maximum luminous intensity of the Yb:YAG nanopowders can be obtained when the microwave radiation is 30 min.

Preparation and Characterization of Al<sub>2</sub>O<sub>3</sub>/ZrO<sub>2</sub> Composite Ceramics

Alumina-zirconia (Al2O3-ZrO2) composite ceramics were prepared by means of cross spraying and hydrothermal method under atmospheric pressure with nanometer powders doped with ZrO2 as the raw material. Then, the prepared powders and ceramics were characterized by SEM, XRD and BET methods. The results showed that combining cross spraying with hydrothermal method under atmospheric pressure could improve the dispersity of the ZrO2 composite ceramics nanopowders, while adding Al2O3 accelerated the low temperature sintering for 3Y-ZrO2 and improved the bending strength, fracture toughness and density of ZrO2 composite ceramics. In addition, through optimization the bending strength and fracture toughnessof the obtained ceramic, were 1,150 MPa and 8.2 MPa∙m1/2 respectively.

Synthesis and Characterization of Nanocrystalline La0.65Sr0.3 MnO3 and La0.8Sr0.2MnO3 Cathode Powders by Auto-ignition Technique for Solid Oxide Fuel Cells (SOFC)

Solid Oxide fuel Cells (SOFCs) are considered to be one of the most promising energy conversion devices that have several advantages such as high efficiency, system compactness and low environmental pollution. In the present investigation La0.65Sr0.3MnO3 (LSM-1) and La0.8Sr0.2MnO3 (LSM-2) nanoceramic powders were prepared by citrate-nitrate route of auto-combustion with citrate to nitrate (c/n) ratio 0.50 to see the effect of these cathode powders on the performance of SOFC cells. The as prepared powder were calcined at 900oC for 4hrs using the Thermolyne 47900 furnace to remove carboneous residues and characterized them using SEM / EDS, XRD, TGA techniques and their results are presented . From calculations using Debye Scherrer’s equation, the average crystallite size of the powders were found to be around 16nm. The SEM indicates the particle sizes are within the range of around 200nm.The surface area of the calcined LSM-2 powder was found to be ~21m2/g. The TGA studies indicate the completion of combustion since there was no further weight loss after reaching temperature of ~ 650oC.
 Also, Electrochemical characterization of LSM cathode powders were carried out by coating these powders (as cathode functional layer CFL-Bottom and current collector layer CL- Top) using Screen printing on the SOFC half cells (NiO-YSZ+YSZ) procured from CGCRI, Kolkata, India with a cell size of 16mm dia x1.6mm and tested these cells with H2-O2 at 750-800oC with the flow rates of 100-200 sccm. The results of the performances of single cells are presented in this paper. The Current density and powder density values obtained are 0.80A/cm2 (at 0.7V) and 0.55 W/cm2 at 800oC with 200 sccm of hydrogen and oxygen respectively. The area surface resistance (ASR) values obtained were ~0.50 Ωcm2 at 0.7V at 800oC.

Synthesis and electric field-assisted sintering behavior of Al2O3–ZrO2 composite nanopowders by polyacrylamide gel method

Al2O3–ZrO2 composite ceramic nanopowders were synthesized using a polyacrylamide gel method. The mean particle size of the Al2O3–ZrO2 nanopowders was found to decrease with increasing mole ratio of monomer to the precursor salt. The Al2O3–ZrO2 nanopowders with mean particle size of 10 nm can be densified in 1 h at 965 °C, by application of a dc electrical field. Under a constant dc electrical field, the current density through the sample of Al2O3–ZrO2 rose rapidly when the temperature increased to a certain value. In the sintering process, the current density was restricted when a sharp increase occurred. It was found that current density had a great effect on the sintering process in electric field-assisted sintering. Joule heating was proposed to be the main mechanism of the electric field-assisted sintering process. The Al2O3–ZrO2 composite ceramic nanopowders were synthesized using a polyacrylamide gel method. The Al2O3–ZrO2 nanopowders can be densified in 1 h at low temperature, by the application of a dc electrical field. Under a constant dc electrical field, the current density through the sample of Al2O3–ZrO2 rose rapidly when the temperature increased to a certain value.

Studying the Effect of Nano Additives and Coating on Some Properties of Cement Mortar Mixes

The experimental work is divided in two parts, in the first part was prepared the mortar samples and mixing proportions cementsand (1:3)they were mixing these samples with nano scale ceramic powders (ZrO2 and TiO2) respectively the percentages by weight are taken from cement ratio (0.1, 1, 2.5, 5, and 10%) at particle size (50nm) and curing time (28day). The second part has included the preparation of mortar samples and then coated with a mixture of methanol alcohol, cement and ceramic nano-powders by cold spray technique by using compressed air at room temperature with pressure (8bar) and the spray distance (20Cm) and heating of the samples at (75C°), and then study mechanical thermal physical and structural properties for prepared samples. The results of mechanical and physical tests showed large and significant improvement for all mixed and coated samples with nanoparticles, and that the highest value of the mechanical and physical properties obtained from cement coated samples with (%5ZrO2), reaching the rate of increase in values of Vickers hardness by (%54), and wear resistance increased by (%66), while reaching the rate of decrease in values of total water absorption by (%79), The porosity has decreased at a rate of (%65), With regard to the dry density has increased at a rate of (%2.3). The higher values for the mixed samples reaching the rate of increase in values of Vickers hardness by (%38), and wear resistance increased by (%58), while reaching the rate of decrease in values of total water absorption by (%67), The porosity has decreased at a rate of (%51.68), With regard to the dry density has increased at a rate of (%1.9). The thermal conductivity test results have shown that there is a marked decrease in values conductivity for all mixed and coated samples with nanoparticles and that the minimum value of conductivity obtained from coated and mixed samples with (%5TiO2) as the value decreases conductivity for coated samples by (%64), while the lowest value for conductivity to the mixed samples by (%49). Results of Characterizations tests showed images of all of (SEM and AFM) Mortar reference sample that a high roughness as well as having to structure Ca(OH)2 a needle shaped structures with the presence of large pores, while after adding and coating by nanoparticles shows the disappearance of structures needle and produce a homogeneous structure of compounds (C-S-H) and the disappearance of the pores and gaps further decrease in surface roughness this explains the clear improvement in the properties.

Impedance characterization of Cr3+, Y3+ and Zr4+ activated forsterite nanoceramics synthesized by sol–gel method

The synthesis of forsterite-based ceramic nanopowders using sol–gel method assisted by further thermal treatment has been performed. X-ray diffraction and SEM analysis of the obtained nanopowders are presented. Detailed impedance spectroscopy study of the forsterite nanoceramics doped with Cr3+, Y3+ and Zr4+ ions has been carried out. Impedance spectra are interpreted in terms of equivalent circuits. Peculiarities of the electrical properties for each of the materials under study are discussed.

Improved Electrochemical Performance of Lithium Oxygen Batteries with N-methyl-2-pyrrolidone Based Composite Polymer Electrolytes

The stability and reversibility of the electrolytes is a significant limitation for cycle life performance of Lithium oxygen (Li-O2) batteries. Therefore, the traditionally used ionic/liquid electrolytes need to be modified with ceramic or polymer fillers to reach stable and reversible polymer composite electrolytes. Here, to increase reversibility and stability of the N-methyl-2-pyrrodione (NMP) based electrolytes, which is known as an ideal candidate to overcome electrolyte difficulties due to its attractive properties such as low flammability, viscosity and comparatively low toxicity, polymer supported liquid composites were synthesized using poly(vinylidene fluoride) (PVDF) and polyethylene oxide (PEO) polymers and aluminum oxide (Al2O3) nano ceramic powders. By preparing a suitable composite polymer electrolyte using a NMP aprotic solvent, we demonstrate a Li-O2 battery which is capable of operating over 35 cycles with a capacity of 2.54 mAh. This study proved that ionic conductivity and over potential of the cell was greatly improved with the addition of polymer and ceramic additive in NMP based electrolyte. Moreover, our composite polymer electrolytes provided highly reversible Li-O2 reaction during charging/discharging and prevented clogging of the porous structure of the cathode which is beneficial to increase the cycle performance.