Production of BaTiO2 Nanocrystalline Powders by High Energy Milling and Piezoelectric Properties of Corresponding Ceramics

2013 ◽  
Vol 547 ◽  
pp. 133-138
Author(s):  
K. Chandramani Singh ◽  
Chongtham Jiten
Keyword(s):  
Particle Size ◽  
Piezoelectric Properties ◽  
Average Particle Size ◽  
Hysteresis Loops ◽  
Functional Materials ◽  
High Energy ◽  
Nanocrystalline Powders ◽  
Average Particle ◽  
Ceramic Samples ◽  
Energy Ball

Barium titanate (BaTiO3 or BT) has become one of the most studied functional materials due to its potential application as multilayer ceramic capacitors, PTC thermistors, electromechanical devices, piezoelectric transducers, actuators, dynamic RAM or logic circuitry as well as a great variety of electro-optical devices. In the present study, high energy ball milling has been used to produce nanocrystalline powders of BT. Two categories of powders having average particle size of 35 nm and 25 nm were prepared by setting the milling speed at 250 rpm and 300 rpm respectively, fixing the milling time at 30 hours. Four ceramic samples, BT35-1350, BT25-1350, BT35-1400 and BT25-1400, were formed by sintering the two types of powders at 1350oC and 1400oC for 3 hours. The ferroelectric and piezoelectric properties of the ceramic samples were studied and found to be dependent on the size of the starting nanopowders. The bulk density and piezoelectric constant (d33) of B25-1350 were found to be less than those of BT35-1350, while the reverse was true in case of BT25-1400 and BT35-1400. Well saturated P-E hysteresis loops were observed for all the ceramics with the size and shape of the loops appearing different for the four samples. For both the pairs of ceramics sintered at 1350oC and 1400oC, the remnant polarization (Pr) decreases with starting particle size, that is, as we go from BT35-1350 to BT25-1350 as well as from BT35-1400 to BT25-1400. However, with decreasing particle size of the starting powders, the coercive field (Ec) increases for the ceramics sintered at 1350oC and decreases for the ceramics sintered at 1400oC. The study reveals the importance of an optimized combination of the size of the starting nanopowders and sintering temperature for obtaining BT ceramics with the desired properties.

Effect of VC/Cr3C2 Additions on Microstructure and Mechanical Properties of WC-16TiC-XTaC-10Co Ultrafine Cemented Carbides

2012 ◽  
Vol 476-478 ◽  
pp. 1214-1217 ◽  
Author(s):  
Chong Cai Zhang ◽  
Quan Wang ◽  
Qun Qun Yuan ◽  
Long Wang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Ball Milling ◽  
Rupture Strength ◽  
Average Particle Size ◽  
High Energy ◽  
Cemented Carbides ◽  
Average Particle ◽  
Hardness Increase ◽  
Energy Ball

In this paper, the WC-16TiC-xTaC-10Co mixture mixed by WC 0.52μm, (W, Ti, Ta)C 2.9μm and Co1.36μm and prepared by high-energy ball milling, changed the VC and Cr3C2 adding amount. After ball milling for 60 hours, an average particle size of 220nm powder was prepared and it was cold isostatic pressed at 300MPa and vacuum sintered at 1410°C. The physical properties and the micrographs of samples were detected. The main conclusions are as follow: the coercivity and hardness increase and Cobalt magnetic decreases with the content of Cr3C2 increasing, the transverse rupture strength (TRS) does not vary. The VC and Cr3C2 inhibit the growth of WC grain, but can’t inhibite the (W, Ti, Ta)C grain growth effectively.

Low Temperature Hydrothermal Synthesis of Nanophase BaTiO3 and BaFe12O19 Powders

1996 ◽  
Vol 457 ◽  
Author(s):  
Fatih Dogan ◽  
Shawn O'rourke ◽  
Mao-Xu Qian ◽  
Mehmet Sarikaya
Keyword(s):  
Particle Size ◽  
Hydrothermal Reaction ◽  
Average Particle Size ◽  
Reaction Times ◽  
Nanocrystalline Powders ◽  
Molar Ratio ◽  
Average Particle ◽  
Hydrothermal Conditions ◽  
Processing Variables ◽  
Xrd And Tem

ABSTRACTNanocrystalline powders with an average particle size of 50 nm has been synthesized in two materials systems under hydrothermal conditions below 100°C. Processing variables, such as temperature, concentration and molar ratio of reactants and reaction time were optimized to obtain particles of reduced size and stoichiometric compositions. Hydrothermal reaction takes place between Ba(OH)2 solution and titanium/iron precursors in sealed polyethylene bottles in the BaTiO3 and BaFe12O19 systems, respectively. While crystalline BaTiO3 forms relatively fast within a few hours, formation of fully crystalline and stoichiometric BaFei20i9 require considerably longer reaction times up to several weeks and strongly dependent on the Ba:Fe ratio of the precursors. The structural and compositional evaluation of the nanophase powders were studied by XRD and TEM techniques.

Nanostructured Al Powder Obtained by High Energy Ball Milling at Ambient and Cryogenic Temperatures

2014 ◽  
Vol 802 ◽  
pp. 125-129
Author(s):  
Heronilton Mendes de Lira ◽  
Pilar Rey Rodriguez ◽  
Oscar Olimpio de Araújo Filho ◽  
Cezar Henrique Gonzalez ◽  
Severino Leopoldino Urtiga Filho
Keyword(s):  
Particle Size ◽  
Ball Milling ◽  
High Performance ◽  
Pure Aluminum ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Nanocrystalline Powders ◽  
Protective Atmosphere ◽  
Energy Ball ◽  
Size And Morphology

High performance nanostructured light metals and alloys are very interesting for replacing conventional heavier materials in many industrial components. High Energy Ball Milling and Cryomilling are useful techniques to obtain nanocrystalline powders. In this work the effect of several milling conditions such as rotation speed, time, ball to powder ratio and temperature on the crystallite and particle size and morphology in pure aluminum are presented. X-Ray Diffraction, Laser Diffraction and Scanning Electron Microscopy are used. High energy ball milling at ambient and cryogenic temperature of Al powders rapidly leads to a nanometer size down to about 35 nm. High ball to powder ratio promotes both low crystallite and particle size. Small crystallite size like 18 nm and particle size as 4 μm were achieved in the most energetic conditions at ambient temperature. Isopropyl alcohol used as liquid media and protective atmosphere has a strong influence on the results depending on the milling temperature of Al.

scholarly journals The influence of powder particle size on properties of Cu-Al2O3 composites

2009 ◽  
Vol 41 (2) ◽  
pp. 185-192 ◽  
Author(s):  
V. Rajkovic ◽  
D. Bozic ◽  
M. Popovic ◽  
M.T. Jovanovic
Keyword(s):  
Thermal Stability ◽  
Particle Size ◽  
Grain Size ◽  
Copper Powder ◽  
Average Particle Size ◽  
High Energy ◽  
Average Particle ◽  
Size Refinement ◽  
Al2o3 Particles ◽  
Milled Powders

Inert gas atomized prealloyed copper powder containing 2 wt.% Al (average particle size ? 30 ?m) and a mixture consisting of copper (average particle sizes ? 15 ?m and 30 ?m) and 4 wt.% of commercial Al2O3 powder particles (average particle size ? 0.75 ?m) were milled separately in a high-energy planetary ball mill up to 20 h in air. Milling was performed in order to strengthen the copper matrix by grain size refinement and Al2O3 particles. Milling in air of prealloyed copper powder promoted formation of finely dispersed nano-sized Al2O3 particles by internal oxidation. On the other side, composite powders with commercial micro-sized Al2O3 particles were obtained by mechanical alloying. Following milling, powders were treated in hydrogen at 400 0C for 1h in order to eliminate copper oxides formed on their surface during milling. Hot-pressing (800 0C for 3 h in argon at pressure of 35 MPa) was used for compaction of milled powders. Hot-pressed composite compacts processed from 5 and 20 h milled powders were additionally subjected to high temperature exposure (800?C for 1 and 5h in argon) in order to examine their thermal stability. The results were discussed in terms of the effects of different size of starting powders, the grain size refinement and different size of Al2O3 particles on strengthening, thermal stability and electrical conductivity of copper-based composites.

Diffusion in Nanocrystalline Ion Conductors Studied by Solid State NMR and Impedance Spectroscopy

2009 ◽  
Vol 283-286 ◽  
pp. 705-715 ◽  
Author(s):  
Paul Heitjans ◽  
Martin Wilkening
Keyword(s):  
Dynamic Properties ◽  
Average Particle Size ◽  
High Energy ◽  
Average Particle ◽  
Ion Dynamics ◽  
Ionic Conductors ◽  
Present Contribution ◽  
Energy Ball ◽  
Phase Systems ◽  
Ion Conductors

Materials with an average particle size of less than about 50 nm often show new or at least enhanced physical properties. In many cases nanocrystalline ionic conductors exhibit a high increase of cation, e. g. Li+, or anion, e. g. F−, diffusivity. In the present contribution we review recent studies on ion dynamics in nanocrystalline ion conductors, both single-phase systems and composites, being prepared by high-energy ball milling. These include, e.g., LiTaO3, Li2O:Al2O3, LiF:Al2O3, BaF2, CaF2, BaF2:CaF2 and (BaF2:CaF2):Al2O3. Dynamic properties were probed by 7Li and/or 19F NMR line shape and relaxation as well as ion conductivity measurements.

Densification Process of WC-MgO Nanocomposite Based on Master Sintering Curve

2012 ◽  
Vol 152-154 ◽  
pp. 232-238
Author(s):  
Chen Xin Ouyang ◽  
Shi Gen Zhu
Keyword(s):  
Average Particle Size ◽  
High Energy ◽  
Average Particle ◽  
Densification Process ◽  
Heating Rates ◽  
Final Density ◽  
Energy Ball ◽  
Constant Heating ◽  
Heating Up ◽  
And Control

The master sintering curve (MSC) of nanocomposite WC-MgO was constructed based on the combined-stage sintering model. Nano-sized WC-4.3wt%MgO powder with average particle size of 35nm was synthesized by high-energy ball milling, and then uniaxially pressed at the pressure of 500MPa to fabricate green compacts. The shrinkage response of the compacts, used to construct the master sintering curve, were studied by dilatometric runs at two constant heating rates of 5°C/min and 10°C/min up to 1900°C. Using the estimated activation energy, the master sintering curves were established and compared to acquire an optimum value (Q=361.8 kJ/mol). The obtained MSC was validated by non-isothermal sintering with the identical green compacts. The results demonstrate that the MSC can be applied successfully to predict and control shrinkage level and final density during heating up regardless of heating rates.

Microstructural Characterization of 66%Co-28%Cr-6%Mo Dental Alloy Powder Obtained by High-Energy Ball Milling

2014 ◽  
Vol 802 ◽  
pp. 51-55 ◽  
Author(s):  
Claudinei dos Santos ◽  
Alexandre Fernandes Habibe ◽  
Durval Rodrigues ◽  
José C. Minatti ◽  
Jefferson Fabrício C. Lins ◽  
...  
Keyword(s):  
Ball Milling ◽  
Average Particle Size ◽  
Microstructural Characterization ◽  
High Energy ◽  
Inert Atmosphere ◽  
High Energy Ball Milling ◽  
Average Particle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Energy Ball

In this work, the microstructural features of the particles based on 66% Co-28% Cr-6% Mo alloy, were investigated by X-ray diffraction and Scanning electron microscopy (SEM). Powders obtained by high-energy ball milling in an inert atmosphere, and held in SPEX mill with times between 15min and 120min, about ball/powder ratio of 6:1, were characterized by X-ray diffraction indicating in all conditions, Co phase as the crystalline phase of the system. The powders have a morphology that indicate a continuous reduction in average particle size as a function of increasing time, however, the shape of the particles initially flat for times up to 30 minutes, becomes spherodized after 30 minutes of grinding.

scholarly journals Structure and piezoelectric properties of cazro3-modified (K,Na,Li)(Nb,Sb)O3 ceramics prepared from powders synthesized by microwave heating

2019 ◽  
Vol 13 (4) ◽  
pp. 368-375
Author(s):  
Xingrui Li ◽  
Bingbing Fan ◽  
Haowei Jia ◽  
Xuewen Shi ◽  
Yilin Zhang ◽  
...  
Keyword(s):  
Particle Size ◽  
Microwave Heating ◽  
Piezoelectric Properties ◽  
Average Particle Size ◽  
Average Particle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dense Microstructure ◽  
Good Crystallinity ◽  
Short Time

CaZrO3-modified (K0.48Na0.48Li0.04)(Nb0.95Sb0.05)O3 (CZ-KNLNS) lead-free piezoelectric powders were synthesized by microwave method followed by conventional solid state sintering. Different amounts of CaZrO3 were added (i.e. x = 0, 0.02, 0.03, 0.04, 0.06 mol) and their effects on the crystal structure, microstructure, as well as the electrical properties, were investigated. The results showed that CZ-KNLNS powders could be obtained by microwave heating at a relatively low temperature and short time of 650 ?C and 10min, respectively. The obtained CZ-KNLNS powders have cubic structure and good crystallinity with average particle size of 300-700 nm. The particle size gradually decreases with the increase of CaZrO3 amount, indicating that addition of CaZrO3 inhibits the growth of the particles. The powders were further sintered at 1120 ?C for 4 h and CZ-KNLNS ceramics with homogeneous and highly dense microstructure were obtained. X-ray diffraction showed that, with increasing CaZrO3 content, the phase structure gradually changed from orthorhombic to rhombohedral, which can be considered as the coexistence zone of orthorhombic-rhombohedral (O-R) phase in the range of 0.03 < x < 0.06. The optimized content of CaZrO3 is x = 0.04, at which the CZ-KNLNS piezoelectric ceramics show good properties and maximum d33 = 201.2 pC/N and Kp = 36.8%.

Characterization of Hematite Nanoparticles (Fe2O3) Produced by High Energy Milling for Dye Removal Catalyst

2015 ◽  
Vol 819 ◽  
pp. 423-428
Author(s):  
Roshaida Arbain ◽  
Norlia Baharun
Keyword(s):  
Particle Size ◽  
Textile Industry ◽  
Large Scale ◽  
Average Particle Size ◽  
Industrial Effluent ◽  
High Energy ◽  
Average Particle ◽  
Hematite Nanoparticles ◽  
Grinding Technique ◽  
Remazol Red

Hematite nanoparticles with average particle size of 75.6 and 93.4 nm were produced by mechanical grinding technique using planetary ball mill. The ground hematite were characterized by X-ray diffraction analysis technique, specific surface area analysis (BET), transmission microscope (TEM) and scanning electron microscope (SEM). The effects of different properties of hematite particles used as a catalyst for decolorization of synthetic dye, Remazol Red 3B (RR3B) were investigated. The experimental results show that smaller particle size of 75.6 nm decolourized at the rate of 95.8% within 10 min reaction while larger particle size of 93.4 nm decolorized at the rate of 95.9% within 60 min reaction. The decolorization of RR3B dye by both catalyst were achieved with minimum iron leached (<5 mgL-1) which fulfill the Malaysian Environmental Quality (Industrial Effluent) Regulations 2009. The continuous mode for decolorization of RR3B was carried out and complete decolorization was achieved with low iron dissolution which demonstrates the possibilities of using milled hematite as catalyst for large-scale textile industry wastewater treatment applications.

Physical Properties of Nanocrystalline MoS2 and WS2 Particles Produced by CO2 Laser Pyrolysis

1993 ◽  
Vol 327 ◽  
Author(s):  
Xiang-Xin Bi ◽  
Ying Wang ◽  
W. T. Lee ◽  
Kai-An Wang ◽  
S. Bandow ◽  
...  
Keyword(s):  
Particle Size ◽  
Structural Phase ◽  
Average Particle Size ◽  
Nanocrystalline Powders ◽  
Average Particle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Laser Pyrolysis ◽  
Transmission Electron ◽  
Size Crystallite

AbstractNanocrystalline powders of 2H-MoS2 and 2H-WS2 with average particle size 5 and 9 nm, respectively, have been produced using C02laser pyrolysis. Typical production rate for these nanoparticles is 2g/hr. Particle size, crystallite size, and the structural phase were determined using X-ray diffraction(XRD), transmission electron microscopy(TEM), and Raman scattering. Particle size effects may have been observed in the Raman-active modes (WS2 and MoS2) and in the band-edge excitons (MoS2).

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