Effects of Microstructure on Oxygen Permeation in Some Perovskite Oxides

1997 ◽  
Vol 496 ◽  
Author(s):  
K. Zhang ◽  
Y. L. Yang ◽  
A. J. Jacobson ◽  
K. Salama
Keyword(s):  
Grain Size ◽  
Boundary Diffusion ◽  
Sintering Temperature ◽  
Perovskite Oxides ◽  
Oxygen Permeation ◽  
Permeation Flux ◽  
Processing Conditions ◽  
Average Grain Size ◽  
Diffusion Paths ◽  
Oxygen Permeation Flux

ABSTRACTThe effects of microstructure on the oxygen permeation in SrCo0.8Fe0.2O3-δ(SCFO) and La0.2 Sr0.8 Fe0.8Cr0.2 O3 (LSFCO) was investigated using disc samples fabricated under different processing conditions. The microstructure of LSFCO remained unchanged when the sintering temperature was increased from 1300 to 1450 °C, but the average grain size of SCFO increased considerably when the sintering temperature was increased from 930 to 1200 °C. The change in grain size was found to have a strong effect on the oxygen permeation flux in SCFO, which increased considerably as the grain size was decreased. This indicates that the contribution of the grain boundary diffusion to the steady state oxygen flux in SCFO is substantial and grain boundaries provide faster diffusion paths in oxygen permeation through the samples.

scholarly journals A case study of the effect of grain size on the oxygen permeation flux of BSCF disk-shaped membrane fabricated by thermoplastic processing

2011 ◽  
Vol 382 (1-2) ◽  
pp. 186-193 ◽  
Author(s):  
Mehdi Salehi ◽  
Frank Clemens ◽  
Ewald M. Pfaff ◽  
Stefan Diethelm ◽  
Colin Leach ◽  
...  
Keyword(s):  
Grain Size ◽  
Oxygen Permeation ◽  
Permeation Flux ◽  
Oxygen Permeation Flux

Catalytic Partial Oxidation of Coke Oven Gas to Syngas over Ni/SiO2 Catalyst Modified by Rare Earth Metal Oxide in a Membrane Reactor

2010 ◽  
Vol 156-157 ◽  
pp. 1024-1028
Author(s):  
Da Hai Hu ◽  
Xiong Gang Lu ◽  
Hong Wei Cheng ◽  
Wei Zhong Ding
Keyword(s):  
Rare Earth ◽  
Partial Oxidation ◽  
Membrane Reactor ◽  
Coke Oven ◽  
Oxygen Permeation ◽  
Catalytic Partial Oxidation ◽  
Permeation Flux ◽  
Coke Oven Gas ◽  
Permeable Membrane ◽  
Oxygen Permeation Flux

The performance of Ni/SiO2 Catalysts modified by La2O3, ZrO2 and CeO2 were tested in a BaCo0.7Fe0.2Nb0.1O3-δ (BCFNO) membrane reactor by catalytic partial oxidation of coke oven gas (COG) under atmospheric pressure. The results show that the oxygen permeation flux increased dramatically with Ni/RxOy/SiO2 (R = La, Zr or Ce) catalysts by adding the element of rare earth especially the La during the reforming reaction. At optimized reaction conditions, the dense oxygen permeable membrane had an oxygen permeation flux around 16.4 ml/cm2•min and a CH4 conversion of 99.2% have been achieved at 900 oC.

scholarly journals Ultrahigh oxygen permeation flux through supported Ba0.5Sr0.5Co0.8Fe0.2O3−δ membranes

2011 ◽  
Vol 377 (1-2) ◽  
pp. 198-205 ◽  
Author(s):  
S. Baumann ◽  
J.M. Serra ◽  
M.P. Lobera ◽  
S. Escolástico ◽  
F. Schulze-Küppers ◽  
...  
Keyword(s):  
Oxygen Permeation ◽  
Permeation Flux ◽  
Oxygen Permeation Flux

Low temperature sintering of nano-SiC using a novel Al8B4C7 additive

2010 ◽  
Vol 25 (3) ◽  
pp. 471-475 ◽  
Author(s):  
Sea-Hoon Lee ◽  
Byung-Nam Kim ◽  
Hidehiko Tanaka
Keyword(s):  
Grain Size ◽  
Liquid Phase ◽  
Low Temperature ◽  
Sintering Temperature ◽  
Applied Pressure ◽  
Liquid Phase Sintering ◽  
Low Temperature Sintering ◽  
Densification Rate ◽  
Sintering Additive ◽  
Average Grain Size

Al8B4C7 was used as a sintering additive for the densification of nano-SiC powder. The average grain size was approximately 70 nm after sintering SiC-12.5wt% Al8B4C7 at 1550 °C. The densification rate strongly depended on the sintering temperature and the applied pressure. The rearrangement of SiC particles occurred at the initial shrinkage, while viscous flow and liquid phase sintering became important at the middle and final stage of densification.

Investigation of Isothermal Treatment on the Structural, Microstructure and Physical Properties of Li2O-Al2O3-SiO2 Glass-Ceramic

2020 ◽  
Author(s):  
Husniyah Aliyah Lutpi ◽  
Hasmaliza Mohamad ◽  
Tuti Katrina Abdullah
Keyword(s):  
Grain Size ◽  
Elevated Temperature ◽  
Physical Properties ◽  
Thermal Shock ◽  
Glass Ceramic ◽  
Crystalline Phase ◽  
Sintering Temperature ◽  
Isothermal Treatment ◽  
Crystalline Phases ◽  
Average Grain Size

Abstract The present work aims to investigate the effects of isothermal treatment on the structural, microstructure and physical properties of Li2O-Al2O3-SiO2 glass-ceramic. Sintering temperature plays a major role in producing the desired lithium aluminosilicate (LAS) glass-ceramic crystalline phases. This work also aims to achieve a low thermal expansion coefficient β-spodumene (LiAlSi2O6) crystalline phase with improved density and lower porosity, which can be useful for the applications with thermal shock properties. The LAS glass-ceramic was fabricated by the melt-quenching technique at 1550 °C for 5 h before being isothermally sintered at an elevated temperature of 900 to 1200 °C for 30 min. The evolution of LAS glass-ceramic crystalline phases was identified using differential thermal analysis and the β-spodumene exothermic peak appeared at 999 °C. Based on the X-ray diffraction results, the complete transformation of β-spodumene from high-quartz solid solution (β-quartz) occurred at 1000 °C. However, the sintering temperature did not change the crystalline phase when sintered above 1000 °C, but the lattice parameter of the crystal structure was slightly altered. Moreover, it was observed that the LAS glass-ceramic grain size increased with temperature, whereby the smallest average grain size recorded (0.61 µm) for LAS glass-ceramic sintered at 1100 °C. Meanwhile, the fully densified LAS glass-ceramic at 1100 ° C was measured at 2.47 g/cm3 with 0.52% porosity. The isothermal treatment at elevated temperature indicated that sintering at 1100 °C provided a denser, less porous, and small average grain size which is preferred for thermal shock resistance applications.

Improving Performance of BaCo0.7Fe0.2Nb0.1O3-δ Ceramic Membrane by a Surface-Coating Layer for Partial Oxidation of Coke Oven Gas

2010 ◽  
Vol 154-155 ◽  
pp. 877-881 ◽  
Author(s):  
Hong Wei Cheng ◽  
Xiong Gang Lu ◽  
Da Hai Hu ◽  
Yu Wen Zhang ◽  
Wei Zhong Ding ◽  
...  
Keyword(s):  
Partial Oxidation ◽  
Surface Coating ◽  
Ceramic Membrane ◽  
Coating Layer ◽  
Coke Oven ◽  
Oxygen Permeation ◽  
Permeation Flux ◽  
Coke Oven Gas ◽  
Oxygen Permeation Flux ◽  
Partial Oxidation Reforming

The BaCo0.7Fe0.2Nb0.1O3-δ (BCFNO) membranes combined with Ce0.8Re0.2O2-δ (Re=La, Y) layer on the permeation side were used for hydrogen production by partial oxidation reforming of coke oven gas (COG). The Ce0.8Re0.2O2-δ improved the oxygen permeation flux of the membrane by 11–28% at 750 oC. The high oxygen permeation flux achieved using the Ce0.8Re0.2O2-δ surface-coating layer in this work are quite encouraging with a maximum value reaching 19.7 ml/cm2•min at 900 oC, which will be promising surface modification materials in the catalytic partial oxidation reforming of COG.

Synthesis of Nanocrystalline 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 Powder by a Citrate Method

2008 ◽  
Vol 368-372 ◽  
pp. 103-105
Author(s):  
Zhi Bin Tian ◽  
Xiao Hui Wang ◽  
Ji Li ◽  
Wei Zhao ◽  
Long Tu Li
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Traditional Method ◽  
Sintering Temperature ◽  
Ph Value ◽  
Precursor Solution ◽  
Milling Process ◽  
Citrate Method ◽  
Nano Powder ◽  
Average Grain Size

A citrate method to synthesize 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 nano-powder was studied. The stable gel was obtained by the control of the pH value and temperature of the precursor solution. The BNBT nano-powder was produced after calcining the xerogel at 600°C~800°C. The average grain size of the powder calcined at 700°C for 3 h is 50 nm, and the grain size of the ceramic sintered at 1080°C is 0.7 μm. The sintering temperature used is 100°C lower than the BNBT ceramic prepared by traditional method, but the electrical properties were comparable. In addition, it was found that the ball-milling process has important effect on the morphology of the ceramics and the orientation crystals were eliminated due to the disintegration of agglomerates during milling.

The Effect of Sintering Temperature on the Crystal Structure and Luminescence Properties of Pr:LSO Polycrystalline Films

2016 ◽  
Vol 852 ◽  
pp. 1080-1086
Author(s):  
Xiao Xin Zhang ◽  
Jian Jun Xie ◽  
Ying Shi ◽  
Ling Cong Fan ◽  
De Bao Lin ◽  
...  
Keyword(s):  
Thin Film ◽  
Grain Size ◽  
Decay Time ◽  
Sintering Temperature ◽  
Coating Layer ◽  
Sol Gel ◽  
Characteristic Emission ◽  
Average Grain Size ◽  
Lutetium Oxyorthosilicate ◽  
Xrd Patterns

Lutetium oxyorthosilicate (Lu2SiO5, LSO) doped with Pr3+ was synthesized on cleaned silicon (111) substrates by sol-gel route with the spin-coating technique. XRD patterns indicated that the films were crystallized into A-type LSO phase at 1000 °C, followed by a phase transition to B-type LSO occurred at 1100 °C. SEM observations revealed that the surface of the films was smooth, homogeneous and crack-free. When the sintering temperature was 1000 °C, the average grain size of the crystal particles was 100-200 nm and the thickness of the thin film was about 380 nm when the coating layer number up to 10. While the sintering temperature was 1100 °C, the average grain size of the crystal particles was 200-300 nm and the thickness of the thin film was about 320 nm also 10 layers. PL spectra showed when under 1000 °C, the quenching concentration of Pr3+ was 0.3 mol%, the characteristic emission peaks was 289 nm and 340 nm and the dominant decay time was 4.64 ns; while under 1100 °C, the quenching concentration of Pr3+ was 0.4 mol%, the characteristic emission peaks was 280 nm and 320 nm and the dominant decay time was 2.61 ns.

Mixed conducting membranes - Macrostructure related oxygen permeation flux

AIChE Journal ◽  
2010 ◽  
Vol 56 (12) ◽  
pp. 3084-3090 ◽  
Author(s):  
Barbara Zydorczak ◽  
Kang Li ◽  
Xiaoyao Tan
Keyword(s):  
Oxygen Permeation ◽  
Permeation Flux ◽  
Oxygen Permeation Flux ◽  
Conducting Membranes
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