Peter Hing - Academia.edu (original) (raw)
Papers by Peter Hing
Walailak Journal of Science and Technology (WJST), Jul 31, 2014
Ba 0.95 FeY 0.05 O 2.81 was prepared by solid state reaction method to study its structure, condu... more Ba 0.95 FeY 0.05 O 2.81 was prepared by solid state reaction method to study its structure, conductivity and thermal expansion coefficients. X-ray powder diffraction at elevated temperatures showed the pure phase at 100-600 °C, then the phase changed at 700-800 °C. Electrical conductivity measurements at different temperatures showed that the conductivity increased with an increasing amount of Co 2 O 3. The highest conductivity was observed for 10 wt%Ba 0.95 FeY 0.05 O 2.81 + 90 wt%Co 2 O 3. Thermal expansion coefficients were measured for different compositions to determine the compatibility with Ce 0.9 Gd 0.1 O 1.95 electrolyte. Results showed that the conductivity and thermal expansion coefficient were sensitive to the composition. The optimum composition was 10 wt%BFY532 + 90 wt%Co 2 O 3 , which gave the highest conductivity at 600-800 °C. The thermal expansion coefficient was 12.79×10-6 o C-1 at 40-800 °C, which is compatible with the Ce 0.9 Gd 0.1 O 1.95 electrolyte.
Ionics, Apr 10, 2017
Single phase polycrystalline BaZr0.3Ce0.5Y0.1Yb0.1O3-δ electrolyte material was prepared by solid... more Single phase polycrystalline BaZr0.3Ce0.5Y0.1Yb0.1O3-δ electrolyte material was prepared by solid state reaction route. Rietveld analysis of the XRD data confirms the tetragonal symmetry in the I4/mcm space group with unit cell parameters of a = b = 6.0567(3) Å and c = 8.5831(5) Å. The addition of ZnO as a sintering additive was found to reduce the sintering temperature and enhance both overall sinterability and grain growth. Sintering temperature was reduced by 200-300ºC and a very high relative density of about 98% was achieved at 1400 o C. Impedance spectroscopy in humidified 5% H2/Ar atmosphere shows that the protonic conductivity at 600 o C was 8.60 x 10-3 S cm-1. Thermal analysis performed in pure CO2 atmosphere shows very good chemical stability up to 1200 o C. Good biaxial flexure strength of 100-200 MPa was reported which makes this material a promising electrolyte material for intermediate temperature solid oxide fuel cells (IT-SOFCs).
Solid State Ionics, May 1, 2017
Ba0.5Sr0.5Ce0.6Zr0.2Gd0.1Y0.1O3-δ (BSCZGY) proton conducting electrolyte material for intermediat... more Ba0.5Sr0.5Ce0.6Zr0.2Gd0.1Y0.1O3-δ (BSCZGY) proton conducting electrolyte material for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been synthesized by a sol-gel modified Pechini process and its sinterability, thermal expansion, microstructure, ionic conductivity and chemical stability have been investigated. Ionic conductivity at 700 ºC was measured to be ~ 8 x 10-3 S cm-1 in wet 5 vol% H2/Ar atmospheres. Chemical stability test in pure CO2 up to 1200 ºC shows that the material is highly stable; better than the stability of BaZr0.3Ce0.5Y0.1Yb0.1O3-δ.
Ionics, 2017
Single phase polycrystalline BaZr0.3Ce0.5Y0.1Yb0.1O3-δ electrolyte material was prepared by solid... more Single phase polycrystalline BaZr0.3Ce0.5Y0.1Yb0.1O3-δ electrolyte material was prepared by solid state reaction route. Rietveld analysis of the XRD data confirms the tetragonal symmetry in the I4/mcm space group with unit cell parameters of a = b = 6.0567(3) Å and c = 8.5831(5) Å. The addition of ZnO as a sintering additive was found to reduce the sintering temperature and enhance both overall sinterability and grain growth. Sintering temperature was reduced by 200-300ºC and a very high relative density of about 98% was achieved at 1400 o C. Impedance spectroscopy in humidified 5% H2/Ar atmosphere shows that the protonic conductivity at 600 o C was 8.60 x 10-3 S cm-1. Thermal analysis performed in pure CO2 atmosphere shows very good chemical stability up to 1200 o C. Good biaxial flexure strength of 100-200 MPa was reported which makes this material a promising electrolyte material for intermediate temperature solid oxide fuel cells (IT-SOFCs).
Walailak Journal of Science and Technology (WJST), Jul 31, 2014
Ba 0.95 FeY 0.05 O 2.81 was prepared by solid state reaction method to study its structure, condu... more Ba 0.95 FeY 0.05 O 2.81 was prepared by solid state reaction method to study its structure, conductivity and thermal expansion coefficients. X-ray powder diffraction at elevated temperatures showed the pure phase at 100-600 °C, then the phase changed at 700-800 °C. Electrical conductivity measurements at different temperatures showed that the conductivity increased with an increasing amount of Co 2 O 3. The highest conductivity was observed for 10 wt%Ba 0.95 FeY 0.05 O 2.81 + 90 wt%Co 2 O 3. Thermal expansion coefficients were measured for different compositions to determine the compatibility with Ce 0.9 Gd 0.1 O 1.95 electrolyte. Results showed that the conductivity and thermal expansion coefficient were sensitive to the composition. The optimum composition was 10 wt%BFY532 + 90 wt%Co 2 O 3 , which gave the highest conductivity at 600-800 °C. The thermal expansion coefficient was 12.79×10-6 o C-1 at 40-800 °C, which is compatible with the Ce 0.9 Gd 0.1 O 1.95 electrolyte.
Journal of Materials Science Letters
BioTechniques, 1993
AutoAnalysis is a new method for detecting and quantitating the trityl cation released each cycle... more AutoAnalysis is a new method for detecting and quantitating the trityl cation released each cycle on automated DNA synthesizers. The trityl (dimethoxytrityl) cation is removed from the growing oligonucleotide after each base addition and is a useful measure of synthesis efficiency. The traditional absorbance method of collecting each trityl effluent with a fraction collector, followed by dilution with an acid solution and careful quantitation by UV/VIS spectroscopy is costly, tedious and prone to error. The absorbance method for trityl cation analysis must usually wait until the synthesis is complete. Interruption of a failed operation, for a variety of reasons, such as an empty reagent reservoir, is thus not possible. Taking advantage of the conductive properties of the trityl cation, immediate and real-time quantitation is now possible by integrating the total conductance of the flowing stream during the detritylation step after each nucleoside addition in DNA synthesis. A conduct...
International Journal of Modern Physics B, 2000
Amorphous carbon coatings (a-C, a-C:H) of less than 100 nm thick were deposited on KBr pellets an... more Amorphous carbon coatings (a-C, a-C:H) of less than 100 nm thick were deposited on KBr pellets and silicon wafer substrate via magnetron sputtering of graphite target in argon, argon/hydrogen and argon/nitrogen atmosphere. Parallel electron energy loss spectroscopy (PEELS) analysis was used to quantify the sp 2/ sp 3 bonding in carbon films. Stand-alone films of amorphous carbon were produced by sputtering onto compressed KBr pellets and then floating off is distilled water for PEELS study. Raman spectroscopy was used to measure the peak intensity ratio of D-band to that of the G-band (IdIg). It shows that higher sp 3 fraction often associates with lower Raman peak ratio (IdIg). At the same time, G-band peak position P g decreases while sp 3 fraction increases.
Surface Engineering, 2000
ABSTRACT During diamond deposition on a titanium substrate using a gas mixture of H2–CH4 (196 : 4... more ABSTRACT During diamond deposition on a titanium substrate using a gas mixture of H2–CH4 (196 : 4), hydrogen easily diffused into the substrate and led to significant microstructural coarsening and a severe loss in Charpy impact energy. In order to prevent the rapid diffusion of hydrogen into the substrate during diamond deposition, three techniques were studied. The first method was to use a post-vacuum annealing treatment to achieve dehydrogenation of a diamond coated titanium specimen. However, the Charpy impact energy could not be restored significantly even after a few hours of annealing. The second method was to apply a barrier interlayer between the diamond coating and titanium substrate. Results showed that even though the sputtered TiN coating and plasma nitrided layer could prevent the rapid diffusion of hydrogen and carbon into the titanium substrate, the deposited diamond coatings had poor adhesion to the substrate. A graded interlayer produced by plasma nitriding followed by plasma carbonitriding was effective in preventing the rapid diffusion of hydrogen and also improving the nucleation rate and adhesion of the diamond coating. The third method was to use a gas mixture of Ar–H2–CH4 instead of the conventional H2–CH4 . With the use of an Ar–H2–CH4 (180 : 16 : 4) mixture, a smooth and nanocrystalline diamond coating was deposited, and there was little change in the substrate microstructure or Charpy impact energy after diamond deposition.
Surface and Interface Analysis, 1999
Surface and Coatings Technology, 1999
Diamond coatings appear to be a promising solution for the improvement of tribological behavior o... more Diamond coatings appear to be a promising solution for the improvement of tribological behavior of titanium alloys. By means of microwave plasma assisted chemical vapor deposition (MW-PACVD), diamond coating has been deposited on pure titanium substrates using CH4/H2 mixtures at moderate temperature (550–600°C). The surface and interface characterization of deposition coating with increasing deposition duration up to 21h has been
Solid State Communications, 2003
ABSTRACT The effect of B-site substitution of Ce4+ on the microstructure of the Pb[Zr0.9(CexTi1−x... more ABSTRACT The effect of B-site substitution of Ce4+ on the microstructure of the Pb[Zr0.9(CexTi1−x)0.1]O3 (0≤x≤0.7) ceramics is studied by transmission electron microscopy (TEM). For x=0, only superlattice reflections are found in the selected area diffraction patterns (SADPs), which correspond to the anti-phase rotation of the oxygen octahedra. Small amount of Ce4+ substitution causes the in-phase tilting of the oxygen octahedra and results in the superlattice reflections. With 7 mol% addition of Ce4+ on the B-site, the superlattice reflections at the pseudocubic positions can be observed, indicative of the existence of the antiferroelectric (AFE) phase. The result conforms to the polarization–electric field (P–E) hysteresis loop measurements on the corresponding bulk ceramic samples.
Journal of Materials Science-materials in Electronics - J MATER SCI-MATER ELECTRON, 1999
FeSbO4-based semiconducting ceramics used as a promising candidate for sensing liquid-petroleum g... more FeSbO4-based semiconducting ceramics used as a promising candidate for sensing liquid-petroleum gas (LPG) are presented here for the first time. Precursor powders of FeSbO4 were prepared by two different methods (i.e., ball-milling and chemical coprecipitation). The solid-state reaction in the Fe2O3-Sb2O3 system was investigated by means of thermal gravimetric-differential thermal analysis (TG-DTA) and X-ray diffraction (XRD). Based on our experimental results and previous work, the diffusion of antimony oxide onto a-Fe2O3 is assumed to be a controlling step of the solid-state reaction. Scanning electron microscopy (SEM) and the BET method were used to characterize the samples calcined at 550 to 1000 °C. It was found that a sudden change in specific surface area, crystallite size and particle size takes place between 550 °C calcining and 600 °C calcining, which has an obvious influence on gas-sensing properties. FeSbO4-based sensors operating at 370 °C show a high sensitivity and se...
Materials Science and Engineering: A, 2000
Titanium alloys are widely used in aerospace and biomedical conditions, however, they are notorio... more Titanium alloys are widely used in aerospace and biomedical conditions, however, they are notorious for the poor tribological properties. The deposition of a well adherent diamond coating is a promising way to solve this problem. In this study, diamond coatings were deposited on pure titanium using microwave plasma assisted chemical vapour deposition (MW-PACVD). Characterisation of diamond coatings was performed using scanning electron microscopy (SEM), laser profilometry, Raman spectroscopy, grazing incidence X-ray diffraction (GIXD) and atomic force microscopy (AFM). Tribological properties of diamond coatings were evaluated using a ball-on-disk wear tester (sliding with Al 2 O 3 balls) and a scratch tester (sliding with diamond pin). Results showed that the friction and wear properties of polycrystalline diamond coatings as well as the wear of the counterface were dependent significantly on the surface roughness, the morphology and crystalline structure of diamond coatings as well as the counterface materials. For (111)-textured diamond coatings with rough surface and sharp asperities sliding with Al 2 O 3 balls, the coefficient of friction was much higher than that of (100)-textured coatings, and the wear of the counterface material was quite high. After polishing the diamond coating, the surface roughness, coefficient of friction and wear of counterface decreased significantly. If sliding with diamond pins, the coefficient of friction of diamond coating shows a quite low and stable value. To improve the tribological properties, a three-step deposition method was proposed to obtain a smooth and nano-crystalline diamond layer on bulk diamond coatings. The so-formed diamond coating showed the highest load bearing capacity, the lowest coefficient of friction and the lowest wear of the counterface.
Materials Letters, 2002
Mn-doped samples with atomic ratios equal to 0.5%, 1% and 3% were prepared by the conventional mi... more Mn-doped samples with atomic ratios equal to 0.5%, 1% and 3% were prepared by the conventional mixed-oxide method from commercial cerium oxide (CeO 2) and manganese oxide (MnO 2) powders. The effect of Mn doping on the densification behavior of CeO 2 was investigated by means of dilatometer and scanning electron microscopy (SEM). It was found that Mn doping reduced sintering temperature and promoted the grain growth dramatically. The sintering kinetics study indicated that under the isothermal sintering condition, the grain growth activation energy, Q, decreased from 731F61 kJ/mol for pure CeO 2 to 593F53 kJ/mol for 1% Mn-doped CeO 2 .
Materials Chemistry and Physics, 2002
The stress-and strain-relaxation behavior of lead zirconate titanate based ceramics is studied by... more The stress-and strain-relaxation behavior of lead zirconate titanate based ceramics is studied by using the three-point bending test. The relaxation behavior has been explained based on the domain reorientation mechanism. It is found that the stress relaxation behavior obeys a logarithmic time law. It has also been experimentally confirmed that above the Curie temperature where all the domains disappear, there is no relaxation in the ferroelectric ceramics.
Journal of Power Sources, 2004
Twenty percentage of Gd 2 O 3-doped ceria solid solution has been prepared as an electrolyte for ... more Twenty percentage of Gd 2 O 3-doped ceria solid solution has been prepared as an electrolyte for solid oxide fuel cells via the conventional mixed-oxide method from high-purity commercial CeO 2 and Gd 2 O 3. The solubility of Gd 2 O 3 in CeO 2 in the temperature range of 1300-1700 • C has been examined based on the measurements of the lattice parameter. It is found that the dissolution of Gd 2 O 3 in CeO 2 is completed at 1600 • C for 5 h. The addition of Gd 2 O 3 increases sintering temperature, retards densification, and also depresses grain growth as compared with undoped CeO 2. The sample sintered at 1550 • C for 5 h has the highest grain boundary conductivity, while the highest grain interior conductivity is achieved for the sample sintered at 1600 • C for 5 h. It is also observed that below 500 • C, the maximum total conductivity is exhibited by the former sample, but above 500 • C, for the latter one.
Walailak Journal of Science and Technology (WJST), Jul 31, 2014
Ba 0.95 FeY 0.05 O 2.81 was prepared by solid state reaction method to study its structure, condu... more Ba 0.95 FeY 0.05 O 2.81 was prepared by solid state reaction method to study its structure, conductivity and thermal expansion coefficients. X-ray powder diffraction at elevated temperatures showed the pure phase at 100-600 °C, then the phase changed at 700-800 °C. Electrical conductivity measurements at different temperatures showed that the conductivity increased with an increasing amount of Co 2 O 3. The highest conductivity was observed for 10 wt%Ba 0.95 FeY 0.05 O 2.81 + 90 wt%Co 2 O 3. Thermal expansion coefficients were measured for different compositions to determine the compatibility with Ce 0.9 Gd 0.1 O 1.95 electrolyte. Results showed that the conductivity and thermal expansion coefficient were sensitive to the composition. The optimum composition was 10 wt%BFY532 + 90 wt%Co 2 O 3 , which gave the highest conductivity at 600-800 °C. The thermal expansion coefficient was 12.79×10-6 o C-1 at 40-800 °C, which is compatible with the Ce 0.9 Gd 0.1 O 1.95 electrolyte.
Ionics, Apr 10, 2017
Single phase polycrystalline BaZr0.3Ce0.5Y0.1Yb0.1O3-δ electrolyte material was prepared by solid... more Single phase polycrystalline BaZr0.3Ce0.5Y0.1Yb0.1O3-δ electrolyte material was prepared by solid state reaction route. Rietveld analysis of the XRD data confirms the tetragonal symmetry in the I4/mcm space group with unit cell parameters of a = b = 6.0567(3) Å and c = 8.5831(5) Å. The addition of ZnO as a sintering additive was found to reduce the sintering temperature and enhance both overall sinterability and grain growth. Sintering temperature was reduced by 200-300ºC and a very high relative density of about 98% was achieved at 1400 o C. Impedance spectroscopy in humidified 5% H2/Ar atmosphere shows that the protonic conductivity at 600 o C was 8.60 x 10-3 S cm-1. Thermal analysis performed in pure CO2 atmosphere shows very good chemical stability up to 1200 o C. Good biaxial flexure strength of 100-200 MPa was reported which makes this material a promising electrolyte material for intermediate temperature solid oxide fuel cells (IT-SOFCs).
Solid State Ionics, May 1, 2017
Ba0.5Sr0.5Ce0.6Zr0.2Gd0.1Y0.1O3-δ (BSCZGY) proton conducting electrolyte material for intermediat... more Ba0.5Sr0.5Ce0.6Zr0.2Gd0.1Y0.1O3-δ (BSCZGY) proton conducting electrolyte material for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been synthesized by a sol-gel modified Pechini process and its sinterability, thermal expansion, microstructure, ionic conductivity and chemical stability have been investigated. Ionic conductivity at 700 ºC was measured to be ~ 8 x 10-3 S cm-1 in wet 5 vol% H2/Ar atmospheres. Chemical stability test in pure CO2 up to 1200 ºC shows that the material is highly stable; better than the stability of BaZr0.3Ce0.5Y0.1Yb0.1O3-δ.
Ionics, 2017
Single phase polycrystalline BaZr0.3Ce0.5Y0.1Yb0.1O3-δ electrolyte material was prepared by solid... more Single phase polycrystalline BaZr0.3Ce0.5Y0.1Yb0.1O3-δ electrolyte material was prepared by solid state reaction route. Rietveld analysis of the XRD data confirms the tetragonal symmetry in the I4/mcm space group with unit cell parameters of a = b = 6.0567(3) Å and c = 8.5831(5) Å. The addition of ZnO as a sintering additive was found to reduce the sintering temperature and enhance both overall sinterability and grain growth. Sintering temperature was reduced by 200-300ºC and a very high relative density of about 98% was achieved at 1400 o C. Impedance spectroscopy in humidified 5% H2/Ar atmosphere shows that the protonic conductivity at 600 o C was 8.60 x 10-3 S cm-1. Thermal analysis performed in pure CO2 atmosphere shows very good chemical stability up to 1200 o C. Good biaxial flexure strength of 100-200 MPa was reported which makes this material a promising electrolyte material for intermediate temperature solid oxide fuel cells (IT-SOFCs).
Walailak Journal of Science and Technology (WJST), Jul 31, 2014
Ba 0.95 FeY 0.05 O 2.81 was prepared by solid state reaction method to study its structure, condu... more Ba 0.95 FeY 0.05 O 2.81 was prepared by solid state reaction method to study its structure, conductivity and thermal expansion coefficients. X-ray powder diffraction at elevated temperatures showed the pure phase at 100-600 °C, then the phase changed at 700-800 °C. Electrical conductivity measurements at different temperatures showed that the conductivity increased with an increasing amount of Co 2 O 3. The highest conductivity was observed for 10 wt%Ba 0.95 FeY 0.05 O 2.81 + 90 wt%Co 2 O 3. Thermal expansion coefficients were measured for different compositions to determine the compatibility with Ce 0.9 Gd 0.1 O 1.95 electrolyte. Results showed that the conductivity and thermal expansion coefficient were sensitive to the composition. The optimum composition was 10 wt%BFY532 + 90 wt%Co 2 O 3 , which gave the highest conductivity at 600-800 °C. The thermal expansion coefficient was 12.79×10-6 o C-1 at 40-800 °C, which is compatible with the Ce 0.9 Gd 0.1 O 1.95 electrolyte.
Journal of Materials Science Letters
BioTechniques, 1993
AutoAnalysis is a new method for detecting and quantitating the trityl cation released each cycle... more AutoAnalysis is a new method for detecting and quantitating the trityl cation released each cycle on automated DNA synthesizers. The trityl (dimethoxytrityl) cation is removed from the growing oligonucleotide after each base addition and is a useful measure of synthesis efficiency. The traditional absorbance method of collecting each trityl effluent with a fraction collector, followed by dilution with an acid solution and careful quantitation by UV/VIS spectroscopy is costly, tedious and prone to error. The absorbance method for trityl cation analysis must usually wait until the synthesis is complete. Interruption of a failed operation, for a variety of reasons, such as an empty reagent reservoir, is thus not possible. Taking advantage of the conductive properties of the trityl cation, immediate and real-time quantitation is now possible by integrating the total conductance of the flowing stream during the detritylation step after each nucleoside addition in DNA synthesis. A conduct...
International Journal of Modern Physics B, 2000
Amorphous carbon coatings (a-C, a-C:H) of less than 100 nm thick were deposited on KBr pellets an... more Amorphous carbon coatings (a-C, a-C:H) of less than 100 nm thick were deposited on KBr pellets and silicon wafer substrate via magnetron sputtering of graphite target in argon, argon/hydrogen and argon/nitrogen atmosphere. Parallel electron energy loss spectroscopy (PEELS) analysis was used to quantify the sp 2/ sp 3 bonding in carbon films. Stand-alone films of amorphous carbon were produced by sputtering onto compressed KBr pellets and then floating off is distilled water for PEELS study. Raman spectroscopy was used to measure the peak intensity ratio of D-band to that of the G-band (IdIg). It shows that higher sp 3 fraction often associates with lower Raman peak ratio (IdIg). At the same time, G-band peak position P g decreases while sp 3 fraction increases.
Surface Engineering, 2000
ABSTRACT During diamond deposition on a titanium substrate using a gas mixture of H2–CH4 (196 : 4... more ABSTRACT During diamond deposition on a titanium substrate using a gas mixture of H2–CH4 (196 : 4), hydrogen easily diffused into the substrate and led to significant microstructural coarsening and a severe loss in Charpy impact energy. In order to prevent the rapid diffusion of hydrogen into the substrate during diamond deposition, three techniques were studied. The first method was to use a post-vacuum annealing treatment to achieve dehydrogenation of a diamond coated titanium specimen. However, the Charpy impact energy could not be restored significantly even after a few hours of annealing. The second method was to apply a barrier interlayer between the diamond coating and titanium substrate. Results showed that even though the sputtered TiN coating and plasma nitrided layer could prevent the rapid diffusion of hydrogen and carbon into the titanium substrate, the deposited diamond coatings had poor adhesion to the substrate. A graded interlayer produced by plasma nitriding followed by plasma carbonitriding was effective in preventing the rapid diffusion of hydrogen and also improving the nucleation rate and adhesion of the diamond coating. The third method was to use a gas mixture of Ar–H2–CH4 instead of the conventional H2–CH4 . With the use of an Ar–H2–CH4 (180 : 16 : 4) mixture, a smooth and nanocrystalline diamond coating was deposited, and there was little change in the substrate microstructure or Charpy impact energy after diamond deposition.
Surface and Interface Analysis, 1999
Surface and Coatings Technology, 1999
Diamond coatings appear to be a promising solution for the improvement of tribological behavior o... more Diamond coatings appear to be a promising solution for the improvement of tribological behavior of titanium alloys. By means of microwave plasma assisted chemical vapor deposition (MW-PACVD), diamond coating has been deposited on pure titanium substrates using CH4/H2 mixtures at moderate temperature (550–600°C). The surface and interface characterization of deposition coating with increasing deposition duration up to 21h has been
Solid State Communications, 2003
ABSTRACT The effect of B-site substitution of Ce4+ on the microstructure of the Pb[Zr0.9(CexTi1−x... more ABSTRACT The effect of B-site substitution of Ce4+ on the microstructure of the Pb[Zr0.9(CexTi1−x)0.1]O3 (0≤x≤0.7) ceramics is studied by transmission electron microscopy (TEM). For x=0, only superlattice reflections are found in the selected area diffraction patterns (SADPs), which correspond to the anti-phase rotation of the oxygen octahedra. Small amount of Ce4+ substitution causes the in-phase tilting of the oxygen octahedra and results in the superlattice reflections. With 7 mol% addition of Ce4+ on the B-site, the superlattice reflections at the pseudocubic positions can be observed, indicative of the existence of the antiferroelectric (AFE) phase. The result conforms to the polarization–electric field (P–E) hysteresis loop measurements on the corresponding bulk ceramic samples.
Journal of Materials Science-materials in Electronics - J MATER SCI-MATER ELECTRON, 1999
FeSbO4-based semiconducting ceramics used as a promising candidate for sensing liquid-petroleum g... more FeSbO4-based semiconducting ceramics used as a promising candidate for sensing liquid-petroleum gas (LPG) are presented here for the first time. Precursor powders of FeSbO4 were prepared by two different methods (i.e., ball-milling and chemical coprecipitation). The solid-state reaction in the Fe2O3-Sb2O3 system was investigated by means of thermal gravimetric-differential thermal analysis (TG-DTA) and X-ray diffraction (XRD). Based on our experimental results and previous work, the diffusion of antimony oxide onto a-Fe2O3 is assumed to be a controlling step of the solid-state reaction. Scanning electron microscopy (SEM) and the BET method were used to characterize the samples calcined at 550 to 1000 °C. It was found that a sudden change in specific surface area, crystallite size and particle size takes place between 550 °C calcining and 600 °C calcining, which has an obvious influence on gas-sensing properties. FeSbO4-based sensors operating at 370 °C show a high sensitivity and se...
Materials Science and Engineering: A, 2000
Titanium alloys are widely used in aerospace and biomedical conditions, however, they are notorio... more Titanium alloys are widely used in aerospace and biomedical conditions, however, they are notorious for the poor tribological properties. The deposition of a well adherent diamond coating is a promising way to solve this problem. In this study, diamond coatings were deposited on pure titanium using microwave plasma assisted chemical vapour deposition (MW-PACVD). Characterisation of diamond coatings was performed using scanning electron microscopy (SEM), laser profilometry, Raman spectroscopy, grazing incidence X-ray diffraction (GIXD) and atomic force microscopy (AFM). Tribological properties of diamond coatings were evaluated using a ball-on-disk wear tester (sliding with Al 2 O 3 balls) and a scratch tester (sliding with diamond pin). Results showed that the friction and wear properties of polycrystalline diamond coatings as well as the wear of the counterface were dependent significantly on the surface roughness, the morphology and crystalline structure of diamond coatings as well as the counterface materials. For (111)-textured diamond coatings with rough surface and sharp asperities sliding with Al 2 O 3 balls, the coefficient of friction was much higher than that of (100)-textured coatings, and the wear of the counterface material was quite high. After polishing the diamond coating, the surface roughness, coefficient of friction and wear of counterface decreased significantly. If sliding with diamond pins, the coefficient of friction of diamond coating shows a quite low and stable value. To improve the tribological properties, a three-step deposition method was proposed to obtain a smooth and nano-crystalline diamond layer on bulk diamond coatings. The so-formed diamond coating showed the highest load bearing capacity, the lowest coefficient of friction and the lowest wear of the counterface.
Materials Letters, 2002
Mn-doped samples with atomic ratios equal to 0.5%, 1% and 3% were prepared by the conventional mi... more Mn-doped samples with atomic ratios equal to 0.5%, 1% and 3% were prepared by the conventional mixed-oxide method from commercial cerium oxide (CeO 2) and manganese oxide (MnO 2) powders. The effect of Mn doping on the densification behavior of CeO 2 was investigated by means of dilatometer and scanning electron microscopy (SEM). It was found that Mn doping reduced sintering temperature and promoted the grain growth dramatically. The sintering kinetics study indicated that under the isothermal sintering condition, the grain growth activation energy, Q, decreased from 731F61 kJ/mol for pure CeO 2 to 593F53 kJ/mol for 1% Mn-doped CeO 2 .
Materials Chemistry and Physics, 2002
The stress-and strain-relaxation behavior of lead zirconate titanate based ceramics is studied by... more The stress-and strain-relaxation behavior of lead zirconate titanate based ceramics is studied by using the three-point bending test. The relaxation behavior has been explained based on the domain reorientation mechanism. It is found that the stress relaxation behavior obeys a logarithmic time law. It has also been experimentally confirmed that above the Curie temperature where all the domains disappear, there is no relaxation in the ferroelectric ceramics.
Journal of Power Sources, 2004
Twenty percentage of Gd 2 O 3-doped ceria solid solution has been prepared as an electrolyte for ... more Twenty percentage of Gd 2 O 3-doped ceria solid solution has been prepared as an electrolyte for solid oxide fuel cells via the conventional mixed-oxide method from high-purity commercial CeO 2 and Gd 2 O 3. The solubility of Gd 2 O 3 in CeO 2 in the temperature range of 1300-1700 • C has been examined based on the measurements of the lattice parameter. It is found that the dissolution of Gd 2 O 3 in CeO 2 is completed at 1600 • C for 5 h. The addition of Gd 2 O 3 increases sintering temperature, retards densification, and also depresses grain growth as compared with undoped CeO 2. The sample sintered at 1550 • C for 5 h has the highest grain boundary conductivity, while the highest grain interior conductivity is achieved for the sample sintered at 1600 • C for 5 h. It is also observed that below 500 • C, the maximum total conductivity is exhibited by the former sample, but above 500 • C, for the latter one.