Influence of Excess Bi2O3 and Na2Co3 on Crystal Structure and Microstructure of Bismuth Sodium Titanate Ceramics

2011 ◽  
Vol 474-476 ◽  
pp. 1711-1714 ◽  
Author(s):  
Panadda Sittiketkron ◽  
Arrak Klinbumrung ◽  
Theerachai Bongkarn
Keyword(s):  
Crystal Structure ◽  
Dielectric Properties ◽  
Perovskite Phase ◽  
Average Particle Size ◽  
Sodium Titanate ◽  
Solid State Reaction Method ◽  
Lattice Parameter ◽  
Rhombohedral Structure ◽  
Average Particle ◽  
Average Grain Size

This study investigated the influence of excess Bi2O3 and Na2CO3 on the crystal structure, microstructure and dielectric properties of (Bi0.5Na0.5)TiO3 (BNT) ceramics. The BNT ceramics were synthesized using the solid-state reaction method with various excess Bi2O3 and Na2CO3 levels (0, 1, 2, 3 and 4 mol%). The X-ray characterization revealed that all samples had a rhombohedral structure. A pure perovskite phase was obtained in all samples. The lattice parameter a tended to increase with increased excess Bi2O3 and Na2CO3 content in the calcined powders and sintered ceramics. The average particle size increased while, the average grain size tended to decreased with increased of excess Bi2O3 and Na2CO3 content. The depolarization temperature (Td) and the Curie temperature (Tc) were slightly decreased with the increase of excess Bi2O3 and Na2CO3 content. The dielectric properties were related to the density.

Influences of Firing Temperatures on Phase and Morphology Evolution of (Ba0.25Sr0.75)(Zr0.75Ti0.25)O3 Ceramics Synthesized via Solid-State Reaction Method

2009 ◽  
Vol 421-422 ◽  
pp. 247-250 ◽  
Author(s):  
Atthakorn Thongtha ◽  
Kritsana Angsukased ◽  
Theerachai Bongkarn
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
Perovskite Phase ◽  
Average Particle Size ◽  
Solid State Reaction Method ◽  
Lattice Parameter ◽  
Average Particle ◽  
Strontium Zirconate ◽  
Reaction Method ◽  
Average Grain Size

The effect of calcination (1000-1400 oC) and sintering temperatures (1400-1600 oC) on the phase formation and microstructure of barium strontium zirconate titanate [(Ba0.25Sr0.75)(Zr0.75Ti0.25)O3; BSZT] ceramics were investigated. BSZT powders were prepared by the solid-state reaction method. Higher calcination temperatures increased the percentage of the perovskite phase, but decreased the lattice parameter a of BSZT powders. The pure perovskite phase of BSZT powders was detected above the calcination temperature of 1350 oC. The microstructure of BSZT powders exhibited an almost-spherical morphology and had a porous agglomerated form. The average particle size and the average grain size of the ceramics were increased with the increase of calcination and sintering temperatures. The highest density of the samples was 5.42 g/cm3 which was obtained from ceramic sintered at 1550 oC for 2 h.

Preparation of Barium Strontium Titanate Ceramics via Combustion Method

2008 ◽  
Vol 55-57 ◽  
pp. 185-188
Author(s):  
Theerachai Bongkarn ◽  
C. Wicheanrat
Keyword(s):  
Crystal Structure ◽  
Perovskite Phase ◽  
Average Particle Size ◽  
Combustion Method ◽  
Cubic Phase ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Pure Perovskite Phase ◽  
Average Grain Size ◽  
Titanate Ceramics

This study concentrated on the crystal structure and microstructure of [(Ba0.75Sr0.25)TiO3; (BST)] ceramics at different firing temperatures. The BST powders were prepared by a combustion method. (CO(NH2)2) was used as a fuel. Crystallinity of the calcined powders was improved by increasing the calcining temperature, as indicated by the increase in intensity of the X-ray diffraction peak. The pure perovskite phase of BST powders was obtained with a calcinations condition of 1200 oC. The a axis lattice constant of BST calcined powders and sintered ceramics were calculated and it was found that the crystal structure is a cubic phase. The microstructure of BST calcined powders and sintered ceramics were analyzed by a scanning electron microscope (SEM). The SEM result indicated that the average particle size and average grain size increased with the increase of calcinations and sintering temperatures, respectively. The apparent density of the samples was measured by the Archimedes method.

Fabrication of Barium Stannate Tatanate Ceramics via Combustion Technique

2008 ◽  
Vol 55-57 ◽  
pp. 173-176 ◽  
Author(s):  
C. Wattanawikkam ◽  
Theerachai Bongkarn
Keyword(s):  
Perovskite Phase ◽  
Average Particle Size ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Average Particle ◽  
Calcination Temperatures ◽  
Grain Sizes ◽  
Barium Stannate ◽  
Calcined Temperature ◽  
Combustion Technique

The effect of firing temperatures on phase formation and microstructure of barium stannate titanate [Ba(Sn0.1Ti0.9)O3; BST10] ceramics were investigated. BST10 was synthesized via a combustion method, at various calcination and sintering temperatures. It was found that, a single perovskite of BST10 powders was obtained with a calcinations temperature of 1200 oC. The percent of the perovskite phase and the lattice parameter were increased with increasing calcination temperatures. The average particle size was increased from 0.48 to 1.69 µm by increasing the calcined temperature from 600 to 1200 oC. The average grain sizes were increased from 0.99 to 17.77 µm by increasing the sintering temperature from 1250 to 1450 oC. The maximum density and dielectric constant were observed in sintered samples at 1350 oC.

The Effect of Calcination Temperatures on the Phase Formation and Microstructure of (Pb1-xSrx)TiO3 Powders

2009 ◽  
Vol 421-422 ◽  
pp. 243-246 ◽  
Author(s):  
R. Sumang ◽  
Theerachai Bongkarn
Keyword(s):  
Single Phase ◽  
Average Particle Size ◽  
Solid State Reaction Method ◽  
Lattice Parameter ◽  
Average Particle ◽  
Reaction Method ◽  
X Ray ◽  
Calcination Temperatures ◽  
Powder Samples ◽  
Scanning Electron

(Pb1-xSrx)TiO3 (PST) (x=0.25, 0.50) powders were synthesized by a mixed oxide solid-state reaction method under various calcination temperatures (600-1100oC). Powder samples were characterized using thermogravimetric (TGA), differential thermal analysis (DTA), x–ray diffractrometer (XRD) and scanning electron microscopy (SEM). The results showed that a single-phase of PST for x=0.25 and 0.50 powders was successfully obtained with a calcination condition of 950 oC for 2 h with a heating/cooling rate of 5oC/min. The TGA-DTA results corresponded to the XRD investigation. The lattice parameter a increased whilst the lattice parameter c decreased with increasing calcination temperatures. The tetragonality of powders decreased with an increase of calcination temperatures. The average particle size of the powders increased with the increase of calcination temperature.

Effect of Calcination Temperatures on Microstructure and Phase Formation of Ba(Zr0.25Ti0.75)O3 Powders

2008 ◽  
Vol 55-57 ◽  
pp. 205-208 ◽  
Author(s):  
Theerachai Bongkarn ◽  
N. Phungjitt ◽  
Naratip Vittayakorn
Keyword(s):  
Phase Formation ◽  
Perovskite Phase ◽  
Solid State Reaction Method ◽  
Lattice Parameter ◽  
Average Particle ◽  
Particle Sizes ◽  
Reaction Method ◽  
Calcination Temperatures ◽  
Pure Perovskite Phase ◽  
Second Phases

In this work, the effect of calcination temperatures on the microstructure and phase formation of Ba(Zr0.25Ti0.75)O3 (BZT) powders were investigated. The BZT powders were prepared via the solid state reaction method under various calcination temperatures. It was found that the second phases such as BaCO3, ZrO2, BaZrO3 and Ba2ZrO4 existed in samples with calcination temperature below 1200 oC. Homogeneity and a highly pure perovskite phase of the BZT powders were obtained with calcination condition at 1300 oC for 4 h. Lattice parameter a and the percentage of cubic perovskite phase tended to increase with increasing calcination temperatures. The TG-DTA results corresponded to the XRD investigation. The microstructures of calcined powders exhibited an almost-spherical morphology and had a porous agglomerated form in all samples. The average particle sizes were increased from 0.2 to 1.1mµ when calcination temperatures were increased from 800 to 1350 oC.

Fabrication and Characterization of Perovskite SrZrO3 Ceramics through a Combustion Technique

2009 ◽  
Vol 421-422 ◽  
pp. 223-226 ◽  
Author(s):  
Atthakorn Thongtha ◽  
Theerachai Bongkarn
Keyword(s):  
Perovskite Phase ◽  
Average Particle Size ◽  
Maximum Density ◽  
Average Particle ◽  
Morphology Evolution ◽  
Calcination Temperatures ◽  
Average Grain Size ◽  
Fabrication And Characterization ◽  
Combustion Technique

Perovskite SrZrO3 ceramics were successfully prepared via a combustion technique. The effect of calcination temperatures (900-1400oC) and sintering temperatures (1400-1650oC) on phase and morphology evolution of perovskite SrZrO3 ceramics were studied. The highest purity of perovskite phase powder was obtained at 1250 oC and the purity of the perovskite phase of SrZrO3 ceramics were detected in the samples sintered at 1550 oC for 6 h. The SEM results showed the average particle size (84-214 nm) and the average grain size (0.35-2.09 µm) of samples increased with the increase of firing temperatures. The shrinkage of the ceramics increased as the sintering temperatures increased. The maximum density was ~98.4% of the theoretical density for the sample sintered at 1550 oC for 6 h.

Effects of Calcination Temperatures on Phase and Morphology Evolution of (Ba0.25Sr0.75)(Zr0.75Ti0.25)O3 Powders Synthesized via Solid-State Reaction and Combustion Technique

2008 ◽  
Vol 55-57 ◽  
pp. 197-200 ◽  
Author(s):  
Atthakorn Thongtha ◽  
Kritsana Angsukased ◽  
Theerachai Bongkarn
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
Perovskite Phase ◽  
Solid State Reaction Method ◽  
Lattice Parameter ◽  
Average Particle ◽  
Strontium Zirconate ◽  
Reaction Method ◽  
Calcination Temperatures ◽  
Combustion Technique

The effect of calcination temperatures (1000-1400 oC) on the phase formation and microstructure of barium strontium zirconate titanate [(Ba0.25Sr0.75)(Zr0.75Ti0.25)O3 ; BSZT] powders were investigated. BSZT powders were prepared and compared by the solid state reaction method and the combustion technique. The higher calcination temperatures increased the percentage of the perovskite phase, but decreased the lattice parameter a. The same crystallographic pure perovskite phase of BSZT powders, which were prepared via the combustion technique were detected above 1300 oC ; which was lower than the calcinations temperature of mixed oxide method by 50 oC. The TGA-DTA results corresponded to XRD investigation. The microstructure of BSZT powders, which were prepared using both techniques, exhibited an almost-spherical morphology and had a porous agglomerated form. The average particle sizes of BSZT powders prepared via the combustion technique (0.13-0.30 µm) and the solid state reaction method (0.18-0.38 µm) were increased with the increase of calcinations temperatures

The Effect of Excess PbO on Crystal Structure and Microstructure of (Pb0.925Ba0.075)TiO3 Ceramics

2008 ◽  
Vol 55-57 ◽  
pp. 177-180 ◽  
Author(s):  
Theerachai Bongkarn ◽  
R. Sumang
Keyword(s):  
Crystal Structure ◽  
Barium Titanate ◽  
Lead Oxide ◽  
Lead Dioxide ◽  
Average Particle Size ◽  
Impurity Phase ◽  
Average Particle ◽  
Ceramic Samples ◽  
Average Grain Size ◽  
Structure And Microstructure

In this work, we studied the effect of excess PbO doping on lead barium titanate [(Pb0.925Ba0.075)TiO3; (PBT)] ceramic. PBT was prepared via a mixed oxide method with various PbO levels (-3, 0, 1, 3, 5 and 10 wt.%). The excess PbO was added to compensate the loss from evaporation during calcination and sintering at 800 oC and 1150 oC. It was found that lead barium titanate powders indexed in a tetragonal structure. Impurity phases of lead oxide (PbO), titanium oxide (TiO), and lead dioxide (PbO2) were detected in the calcined powders with higher than 1 wt% of excess PbO. The impurity phase was not obtained in any ceramic samples. The c/a ratios decreased with an increasing excess of PbO in both calcined powders and sintered pellets. The average particle size and the average grain size of the PBT increased with the increase of PbO. The shrinkage plots showed a maximum peak for the 1 wt.% sample which was also the most dense sample.

Microstructure Characterization of Ag Nanoparticles Prepared by Hydrothermal Method

2012 ◽  
Vol 476-478 ◽  
pp. 1138-1141
Author(s):  
Zhi Qiang Wei ◽  
Qiang Wei ◽  
Li Gang Liu ◽  
Hua Yang ◽  
Xiao Juan Wu
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Hydrothermal Method ◽  
Ag Nanoparticles ◽  
Average Particle Size ◽  
Average Particle ◽  
Face Centered Cubic ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Face Centered

Ag nanoparticles were successfully synthesized by hydrothermal method under the polyol system combined with traces of sodium chloride, Silver nitrate(AgNO3) and polyvinylpyrrolidone (PVP) acted as the silver source and dispersant respectively. The samples by this process were characterized via X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET) adsorption equation, transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED) to determine the chemical composition, particle size, crystal structure and morphology. The experiment results indicate that the crystal structure of the samples is face centered cubic (FCC) structure as same as the bulk materials, The specific surface area is 24 m2/g, the particle size distribution ranging from10 to 50 nm, with an average particle size about 26 nm obtained by TEM and confirmed by XRD and BET results.

Evolution of microstructure, texture and inhibitor of medium temperature grain-oriented silicon steel

2020 ◽  
Vol 117 (5) ◽  
pp. 510
Author(s):  
Li-Feng Fan ◽  
Xing-Yuan Zhao ◽  
Li-Jun Xiao ◽  
Jiao Huang ◽  
Yuan Xiang Zhang
Keyword(s):  
Surface Layer ◽  
Cold Rolling ◽  
Average Particle Size ◽  
Fiber Texture ◽  
Average Particle ◽  
Central Layer ◽  
Medium Temperature ◽  
Goss Texture ◽  
Average Grain Size ◽  
Hot Rolled

The medium temperature reheating and two-stage cold rolling process were adopted to produce industrialized Grain-oriented silicon steel. Results showed there were three sections (surface layer, transition layer and central layer) along the thickness direction on hot rolled sheets. Surface layer was occupied by complete recrystallization grains with average grain size 42.81 µm, while the central layer mainly consisted of fibrous microstructure. The Goss texture appeared only on surface layer with content 3.44%∼3.65%. After the first cold rolling with 72% reduction and decarburization annealing, the primary recrystallization occurred and average grains size reached 19.0 µm, simultaneously accompanied with texture rotated to λ, γ fiber texture and Goss texture dropped to 2.89%. Adopting the second cold rolling with 58% reduction, the cold rolled sheet consisted of deformed fiber microstructure and the texture maintained γ fiber texture with a peak at {111} <112>. The precipitates in hot rolled sheets comprised Cu2S and few AlN, and the average particle size was ∼14 nm. The inhibitors in the decarburization annealing sheet were mainly AlN, Cu2S, MnS and their composite precipitation, which were spherical or massive with the average particle size ∼21 nm. The single Goss oriented grains with average grain size 9.41 mm were obtained after high temperature annealing, and the intensity reached 873.30. The final magnetic properties were: B8 = 1.865 T and P1.7/50 = 1.124 W/kg, which met the requirement of 27Q120.

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