Pub Date : 2021-05-18DOI: 10.1080/17436753.2021.1927443
G. Paściak, J. Chmielowiec
ABSTRACT The electrolyte supported intermediate temperature solid oxide fuel cell (IT-SOFC) based on Bi4V2O11 (BIVOX) ceramic stabilised by doping with La was investigated. By adding La to the initial composition of BIVOX, stabilisation of the good oxygen ion-conductive γ phase has been achieved. La addition has significantly increased the lifetime of SOFC due to the improved thermodynamic stability of BIVOX electrolyte in reducing (H2 – fuel) atmosphere. Such fuel cell parameters as: open circuit voltage (OCV), maximum power density (P) and current density (J) in the temperature range 500–800°C and operating time under constant electronic load were determined. Results of the measurements of these electrical parameters for BILAVOX based single cell in function of the operation time and cyclic load changes were also shown. This is the first report on the construction and electrical properties of fuel cells based on BIMEVOX (BIVOX doped with MEtal) ceramics.
{"title":"Novel intermediate temperature solid oxide fuel cell based on La-doped Bi4V2O11 electrolyte","authors":"G. Paściak, J. Chmielowiec","doi":"10.1080/17436753.2021.1927443","DOIUrl":"https://doi.org/10.1080/17436753.2021.1927443","url":null,"abstract":"ABSTRACT The electrolyte supported intermediate temperature solid oxide fuel cell (IT-SOFC) based on Bi4V2O11 (BIVOX) ceramic stabilised by doping with La was investigated. By adding La to the initial composition of BIVOX, stabilisation of the good oxygen ion-conductive γ phase has been achieved. La addition has significantly increased the lifetime of SOFC due to the improved thermodynamic stability of BIVOX electrolyte in reducing (H2 – fuel) atmosphere. Such fuel cell parameters as: open circuit voltage (OCV), maximum power density (P) and current density (J) in the temperature range 500–800°C and operating time under constant electronic load were determined. Results of the measurements of these electrical parameters for BILAVOX based single cell in function of the operation time and cyclic load changes were also shown. This is the first report on the construction and electrical properties of fuel cells based on BIMEVOX (BIVOX doped with MEtal) ceramics.","PeriodicalId":7224,"journal":{"name":"Advances in Applied Ceramics","volume":"138 1","pages":"215 - 221"},"PeriodicalIF":2.2,"publicationDate":"2021-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77423946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-03DOI: 10.1080/17436753.2021.1919361
Jian Dong, M. Biesuz, V. Sglavo, M. Kermani, Xiaojia Su, T. Saunders, Chunfeng Hu, S. Grasso
ABSTRACT We propose an innovative methodology to quantify the dependence of grain growth with respect to current density during flash sintering of zirconia (3YSZ) (field set under a nominal current limit of 150 mA mm−2. This was achieved by using a notch (0.5 mm deep and 1.5 mm wide) located in the middle of a dog-bone specimen, allowing an uneven current distribution (ranging from 3 to 670 mA mm−2) while maintaining a fairly homogeneous temperature (1420–1500 °C). Microstructure observations nearby the notch tip confirmed localised overheating. The modelling approach decoupled thermal and electrical field effects identifying the long questioned athermal electric field effects in flash sintering. Increased current density seems to weakly restrain grain growth, to accelerate densification, to promote defects healing (i.e. notch, cracks and pores) and inter-particle bond formation. These results could rationalise the athermal effects occurring during FS and flash joining.
我们提出了一种创新的方法来量化氧化锆(3YSZ)闪烧过程中晶粒生长与电流密度的依赖关系(场设置在标称电流限制150 mA mm−2下)。这是通过使用位于狗骨标本中间的缺口(0.5 mm深，1.5 mm宽)来实现的，允许不均匀的电流分布(范围从3到670 mA mm−2)，同时保持相当均匀的温度(1420-1500°C)。缺口尖端附近的显微组织观察证实了局部过热。该建模方法解耦了热电场效应，确定了闪烧过程中长期存在的非热电场效应。电流密度的增加似乎对晶粒生长有微弱的抑制作用，加速致密化，促进缺陷愈合(即缺口、裂纹和孔隙)和颗粒间键的形成。这些结果可以合理地解释FS和闪蒸连接过程中出现的非热效应。
{"title":"Athermal electric field effects in flash sintered zirconia","authors":"Jian Dong, M. Biesuz, V. Sglavo, M. Kermani, Xiaojia Su, T. Saunders, Chunfeng Hu, S. Grasso","doi":"10.1080/17436753.2021.1919361","DOIUrl":"https://doi.org/10.1080/17436753.2021.1919361","url":null,"abstract":"ABSTRACT\u0000 We propose an innovative methodology to quantify the dependence of grain growth with respect to current density during flash sintering of zirconia (3YSZ) (field set under a nominal current limit of 150 mA mm−2. This was achieved by using a notch (0.5 mm deep and 1.5 mm wide) located in the middle of a dog-bone specimen, allowing an uneven current distribution (ranging from 3 to 670 mA mm−2) while maintaining a fairly homogeneous temperature (1420–1500 °C). Microstructure observations nearby the notch tip confirmed localised overheating. The modelling approach decoupled thermal and electrical field effects identifying the long questioned athermal electric field effects in flash sintering. Increased current density seems to weakly restrain grain growth, to accelerate densification, to promote defects healing (i.e. notch, cracks and pores) and inter-particle bond formation. These results could rationalise the athermal effects occurring during FS and flash joining.","PeriodicalId":7224,"journal":{"name":"Advances in Applied Ceramics","volume":"6 1","pages":"193 - 201"},"PeriodicalIF":2.2,"publicationDate":"2021-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79630593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-03DOI: 10.1080/17436753.2021.1919362
L. S. Ferreira, E. Muccillo
ABSTRACT Zirconia containing 12 mol-% cerium oxide ceramics were prepared by solid state reaction utilising the conventional, fast firing and two-step sintering methods. The sintering temperature and time were varied aiming to determine ideal sintering profile for these methods. The monoclinic and tetragonal phase contents, microstructure and electrical conductivity of dense specimens were investigated. The linear shrinkage was found negligible up to 1100°C and the maximum rate of shrinkage was achieved at 1150°C. Densification increased up to 2 h for conventional sintered specimens. Stabilisation of tetragonal phase in non-isothermally sintered specimens occurred at a high temperature (1500°C). Specimens sintered by the two-step method attained high density along with small grain sizes. Optimised sintering profiles were determined for all the sintering methods used.
{"title":"Influence of the sintering method on densification, microstructure and electrical conductivity of 12Ce-TZP","authors":"L. S. Ferreira, E. Muccillo","doi":"10.1080/17436753.2021.1919362","DOIUrl":"https://doi.org/10.1080/17436753.2021.1919362","url":null,"abstract":"ABSTRACT Zirconia containing 12 mol-% cerium oxide ceramics were prepared by solid state reaction utilising the conventional, fast firing and two-step sintering methods. The sintering temperature and time were varied aiming to determine ideal sintering profile for these methods. The monoclinic and tetragonal phase contents, microstructure and electrical conductivity of dense specimens were investigated. The linear shrinkage was found negligible up to 1100°C and the maximum rate of shrinkage was achieved at 1150°C. Densification increased up to 2 h for conventional sintered specimens. Stabilisation of tetragonal phase in non-isothermally sintered specimens occurred at a high temperature (1500°C). Specimens sintered by the two-step method attained high density along with small grain sizes. Optimised sintering profiles were determined for all the sintering methods used.","PeriodicalId":7224,"journal":{"name":"Advances in Applied Ceramics","volume":"105 1","pages":"202 - 208"},"PeriodicalIF":2.2,"publicationDate":"2021-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85344641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-28DOI: 10.1080/17436753.2021.1919363
Zongzheng Du, Yi-Xuan Liu, Wenqing Wei, Hong Liu, Shengqi Jiang, Jingzhong Fang
ABSTRACT Herein, Pb0.95Ba0.01Sr0.04(Zr0.53Ti0.47)O3 piezoelectric ceramics comprising 0.25 wt% MnCO3, 1 wt% LiBiO2 and 0.06 wt% CuO (PBSZT-LBCu-Mn ceramics, abbreviated as Mn0.25) were prepared via a conventional method at a low firing temperature of ∼900 °C. The phase structure and temperature-dependent electrical properties were systematically investigated. The product composition possesses the following properties: normalised strain (d 33*) ∼362 pm/V, Curie temperature (T c) ∼336 °C, mechanical quality factor (Q m) ∼568, loss factor (tan δ) ∼0.0058 and relative dielectric constant (ϵ r) ∼872. The remnant polarisation (P r), maximum polarisation (P max) and coercive field (E c) slightly decreased as a function of increasing temperature, while the strain (S pol) was observed to increase. Additionally, d 33* values of 362 and 411 pm/V were achieved at 25 °C and 120 °C, respectively, with a change ratio <14%. The Mn0.25 ceramics exhibit low ϵ r and tan δ values, leading to small average power dissipation, which is beneficial for high-frequency actuator applications.
{"title":"Thermally stable piezoelectric performance in low-temperature sintered Pb0.95Ba0.01Sr0.04(Zr0.53Ti0.47)O3 ceramics with a low loss factor","authors":"Zongzheng Du, Yi-Xuan Liu, Wenqing Wei, Hong Liu, Shengqi Jiang, Jingzhong Fang","doi":"10.1080/17436753.2021.1919363","DOIUrl":"https://doi.org/10.1080/17436753.2021.1919363","url":null,"abstract":"ABSTRACT Herein, Pb0.95Ba0.01Sr0.04(Zr0.53Ti0.47)O3 piezoelectric ceramics comprising 0.25 wt% MnCO3, 1 wt% LiBiO2 and 0.06 wt% CuO (PBSZT-LBCu-Mn ceramics, abbreviated as Mn0.25) were prepared via a conventional method at a low firing temperature of ∼900 °C. The phase structure and temperature-dependent electrical properties were systematically investigated. The product composition possesses the following properties: normalised strain (d 33*) ∼362 pm/V, Curie temperature (T c) ∼336 °C, mechanical quality factor (Q m) ∼568, loss factor (tan δ) ∼0.0058 and relative dielectric constant (ϵ r) ∼872. The remnant polarisation (P r), maximum polarisation (P max) and coercive field (E c) slightly decreased as a function of increasing temperature, while the strain (S pol) was observed to increase. Additionally, d 33* values of 362 and 411 pm/V were achieved at 25 °C and 120 °C, respectively, with a change ratio <14%. The Mn0.25 ceramics exhibit low ϵ r and tan δ values, leading to small average power dissipation, which is beneficial for high-frequency actuator applications.","PeriodicalId":7224,"journal":{"name":"Advances in Applied Ceramics","volume":"4629 2 1","pages":"209 - 214"},"PeriodicalIF":2.2,"publicationDate":"2021-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85311312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-03DOI: 10.1080/17436753.2021.1904767
Pengpeng Yu, Zijia Lin, Y. Mu, Jie Yu
ABSTRACT Silicon carbide (SiC) fibres are widely used as promising reinforcement in ceramic matrix composites due to their excellent mechanical and thermal properties. In this work, sub-micrometer SiC fibres were prepared by electrospinning using polycarbosilane as the precursor, followed by curing in air and pyrolysing at high temperatures. The effect of the microstructure of SiC fibres on mechanical properties was investigated and the SiC fibre mats prepared at 1300°C for 2 h exhibited a mechanical strength of 184.5 ± 19.4 MPa. Hot-drawing was conducted on as-spun fibres during the curing process and the strength, Young’s modulus, and flexibility of SiC fibre mats were improved. The strength with a drawing ratio of 200% reaches 243.0 ± 17.5 MPa. The enhancement of mechanical strength after hot-drawing is mainly attributed to the reduced defects in fibres, improvement in the orientation of the precursor fibres as well as the alignment of the molecular chains in the precursor fibres.
{"title":"Highly flexible and strong SiC fibre mats prepared by electrospinning and hot-drawing","authors":"Pengpeng Yu, Zijia Lin, Y. Mu, Jie Yu","doi":"10.1080/17436753.2021.1904767","DOIUrl":"https://doi.org/10.1080/17436753.2021.1904767","url":null,"abstract":"ABSTRACT Silicon carbide (SiC) fibres are widely used as promising reinforcement in ceramic matrix composites due to their excellent mechanical and thermal properties. In this work, sub-micrometer SiC fibres were prepared by electrospinning using polycarbosilane as the precursor, followed by curing in air and pyrolysing at high temperatures. The effect of the microstructure of SiC fibres on mechanical properties was investigated and the SiC fibre mats prepared at 1300°C for 2 h exhibited a mechanical strength of 184.5 ± 19.4 MPa. Hot-drawing was conducted on as-spun fibres during the curing process and the strength, Young’s modulus, and flexibility of SiC fibre mats were improved. The strength with a drawing ratio of 200% reaches 243.0 ± 17.5 MPa. The enhancement of mechanical strength after hot-drawing is mainly attributed to the reduced defects in fibres, improvement in the orientation of the precursor fibres as well as the alignment of the molecular chains in the precursor fibres.","PeriodicalId":7224,"journal":{"name":"Advances in Applied Ceramics","volume":"44 1","pages":"144 - 155"},"PeriodicalIF":2.2,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73406635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-03DOI: 10.1080/17436753.2021.1911583
Jiawei Zhong, J. Xue, Yong-Qiu Huang
ABSTRACT The R2O–CaO–MgO–Al2O3–SiO2–Fe2O3 glass ceramics was prepared using granite wastes and Fe2O3. The effect of Fe2O3 on crystallisation and properties of glass ceramics was studied. Results show that the crystalline phases were Fe2TiO5 and K(NaCa)Mg5Si8O22F2 when the content of Fe2O3 was low. The main crystalline phase was Fe1.5Ti0.5O3 when the content of Fe2O3 was high. With the increase of Fe2O3, the crystal size of K(NaCa)Mg5Si8O22F2 reduced and the atomic ratio of Si to Mg increased. The colour of sample varied from greyish green to black with different additions of Fe2O3. The flexural strength with a maxim (101.02 MPa) when the content of Fe2O3 was 4.7 mol-%. Given the low cost of granite wastes and Fe2O3, this new type of black glass ceramics is expected to meet the increasing demand from the market of building decoration due to its excellent properties.
{"title":"Effects of Fe2O3 on crystallisation and properties of R2O–CaO–MgO–Al2O3–SiO2–Fe2O3 glass ceramics","authors":"Jiawei Zhong, J. Xue, Yong-Qiu Huang","doi":"10.1080/17436753.2021.1911583","DOIUrl":"https://doi.org/10.1080/17436753.2021.1911583","url":null,"abstract":"ABSTRACT The R2O–CaO–MgO–Al2O3–SiO2–Fe2O3 glass ceramics was prepared using granite wastes and Fe2O3. The effect of Fe2O3 on crystallisation and properties of glass ceramics was studied. Results show that the crystalline phases were Fe2TiO5 and K(NaCa)Mg5Si8O22F2 when the content of Fe2O3 was low. The main crystalline phase was Fe1.5Ti0.5O3 when the content of Fe2O3 was high. With the increase of Fe2O3, the crystal size of K(NaCa)Mg5Si8O22F2 reduced and the atomic ratio of Si to Mg increased. The colour of sample varied from greyish green to black with different additions of Fe2O3. The flexural strength with a maxim (101.02 MPa) when the content of Fe2O3 was 4.7 mol-%. Given the low cost of granite wastes and Fe2O3, this new type of black glass ceramics is expected to meet the increasing demand from the market of building decoration due to its excellent properties.","PeriodicalId":7224,"journal":{"name":"Advances in Applied Ceramics","volume":"85 1","pages":"164 - 168"},"PeriodicalIF":2.2,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85614840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-03DOI: 10.1080/17436753.2021.1911582
H. A. Moghadam, M. H. Paydar
ABSTRACT In this study, paste backward extrusion is introduced for fabrication of sodium beta-alumina electrolyte closed-end tubes (with a wall thickness of 1 mm and external diameter of 8.0 mm). For this purpose, the two-piece extrusion die was designed and extrudable water-based paste was prepared by using sodium beta-alumina powder, polyvinyl pyrrolidone, as a binder, and ethylene glycol as a plasticizer. The effect of solvent content on the rheological parameters of the paste and the ram extrusion velocity on the liquid phase separation are investigated. The results indicate that the optimum solvent content for making the extrudable paste is in the range of 30–35 wt-%, and the liquid phase separation is obviously occurred when the ram velocity is lower than 1.2 mm s−1. It was also shown that by using backward extrusion, and by applying optimum conditions, closed-end tubes with high density (about 97%) and good surface quality could be fabricated successfully.
本研究采用浆料反向挤压法制备了β -氧化铝钠电解质封端管(壁厚为1mm，外径为8.0 mm)。为此，设计了两片式挤出模具，以-氧化铝钠粉、聚乙烯醇吡咯烷酮为粘结剂，乙二醇为增塑剂，制备了可挤出的水基糊状物。考察了溶剂含量对膏体流变参数的影响，以及柱塞挤压速度对液相分离的影响。结果表明，制备可挤出糊状物的最佳溶剂含量为30 ~ 35 wt-%，当滑块速度小于1.2 mm s - 1时，会发生明显的液相分离。结果表明，采用反向挤压工艺，在适当的条件下，可以成功制备出高密度(约97%)、表面质量良好的封端管。
{"title":"Paste backward extrusion process as a suitable method for fabrication of sodium beta-alumina electrolyte closed-end tubes","authors":"H. A. Moghadam, M. H. Paydar","doi":"10.1080/17436753.2021.1911582","DOIUrl":"https://doi.org/10.1080/17436753.2021.1911582","url":null,"abstract":"ABSTRACT In this study, paste backward extrusion is introduced for fabrication of sodium beta-alumina electrolyte closed-end tubes (with a wall thickness of 1 mm and external diameter of 8.0 mm). For this purpose, the two-piece extrusion die was designed and extrudable water-based paste was prepared by using sodium beta-alumina powder, polyvinyl pyrrolidone, as a binder, and ethylene glycol as a plasticizer. The effect of solvent content on the rheological parameters of the paste and the ram extrusion velocity on the liquid phase separation are investigated. The results indicate that the optimum solvent content for making the extrudable paste is in the range of 30–35 wt-%, and the liquid phase separation is obviously occurred when the ram velocity is lower than 1.2 mm s−1. It was also shown that by using backward extrusion, and by applying optimum conditions, closed-end tubes with high density (about 97%) and good surface quality could be fabricated successfully.","PeriodicalId":7224,"journal":{"name":"Advances in Applied Ceramics","volume":"53 1","pages":"156 - 163"},"PeriodicalIF":2.2,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80644593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-03DOI: 10.1080/17436753.2021.1915086
Zhe Sun, Lifang Wu, Jing Zhao, Yuanna Zheng
ABSTRACT Tooth discolouration and the existence of metallic substrates increase the difficulty of restoration to reproduce natural and aesthetic appearance. The commonly used veneered zirconia restorations have a high risk of porcelain chipping, and the monolithic zirconia restorations cannot always achieve satisfying aesthetics. The newly developed self-glazed monolithic zirconia restorations digitally manufactured by additive technique have colour- and translucency-gradient characteristics. They could mask the different coloured substrates and achieve a natural look simultaneously. This clinical report describes the prosthodontic treatments of two patients with different coloured substrates in the anterior region. Both functional and aesthetic outcomes are satisfactory after 1–3 years of follow-up.
{"title":"Aesthetic restoration of anterior teeth with different coloured substrates using digital monolithic zirconia crowns: two case reports","authors":"Zhe Sun, Lifang Wu, Jing Zhao, Yuanna Zheng","doi":"10.1080/17436753.2021.1915086","DOIUrl":"https://doi.org/10.1080/17436753.2021.1915086","url":null,"abstract":"ABSTRACT Tooth discolouration and the existence of metallic substrates increase the difficulty of restoration to reproduce natural and aesthetic appearance. The commonly used veneered zirconia restorations have a high risk of porcelain chipping, and the monolithic zirconia restorations cannot always achieve satisfying aesthetics. The newly developed self-glazed monolithic zirconia restorations digitally manufactured by additive technique have colour- and translucency-gradient characteristics. They could mask the different coloured substrates and achieve a natural look simultaneously. This clinical report describes the prosthodontic treatments of two patients with different coloured substrates in the anterior region. Both functional and aesthetic outcomes are satisfactory after 1–3 years of follow-up.","PeriodicalId":7224,"journal":{"name":"Advances in Applied Ceramics","volume":"17 4","pages":"169 - 174"},"PeriodicalIF":2.2,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/17436753.2021.1915086","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72430968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-03DOI: 10.1080/17436753.2021.1919359
Alina Aftab, Katerina L. Chagoya, Alan Felix, R. Blair, N. Orlovskaya
ABSTRACT Porous Yb2O3 ceramic (55%) was pressureless sintered at 900°C for four hours in air. The crystal structure of Yb2O3 was confirmed to be cubic ( ) with c = 10.43731 Å by neutron diffraction. The spectral vibrational signature of Yb2O3 was also confirmed by micro-Raman spectroscopy. Yb2O3 is an amphoteric oxide with both acid and base character, which presents the potential for producing different hydrocarbons when used as a Fischer–Tropsch (FT) catalyst. It was found that Yb2O3 is indeed catalytically active and can be used to convert syngas (CO + H2) into useful hydrocarbons. Production of methane, ethene, and ethane was detected in the catalytic experiment performed at 500°C, but propane, propene, butane, and methanol were also detected in the experiment performed at 250°C. Hydrocarbons heavier than C4 were not observed. The limited data show deviation from a Flory–Schulz distribution suggesting additional surface processes are occurring beyond chain growth and termination.
{"title":"Catalytic performance of porous Yb2O3 sesquioxide","authors":"Alina Aftab, Katerina L. Chagoya, Alan Felix, R. Blair, N. Orlovskaya","doi":"10.1080/17436753.2021.1919359","DOIUrl":"https://doi.org/10.1080/17436753.2021.1919359","url":null,"abstract":"ABSTRACT Porous Yb2O3 ceramic (55%) was pressureless sintered at 900°C for four hours in air. The crystal structure of Yb2O3 was confirmed to be cubic ( ) with c = 10.43731 Å by neutron diffraction. The spectral vibrational signature of Yb2O3 was also confirmed by micro-Raman spectroscopy. Yb2O3 is an amphoteric oxide with both acid and base character, which presents the potential for producing different hydrocarbons when used as a Fischer–Tropsch (FT) catalyst. It was found that Yb2O3 is indeed catalytically active and can be used to convert syngas (CO + H2) into useful hydrocarbons. Production of methane, ethene, and ethane was detected in the catalytic experiment performed at 500°C, but propane, propene, butane, and methanol were also detected in the experiment performed at 250°C. Hydrocarbons heavier than C4 were not observed. The limited data show deviation from a Flory–Schulz distribution suggesting additional surface processes are occurring beyond chain growth and termination.","PeriodicalId":7224,"journal":{"name":"Advances in Applied Ceramics","volume":"42 1","pages":"175 - 186"},"PeriodicalIF":2.2,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80101232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-03DOI: 10.1080/17436753.2021.1919360
Myung-Kun Kim, G. Park, Min-Chul Shin, Hong-Dae Kim, Dae-Seung Cho, Heesoo Lee
ABSTRACT The enhancement of surface acidity for tungsten-doped CeTiOx was investigated through electronic structure. Tungsten doping increased the ratio of Ce3+ from 12.0% to 29.6%, which was confirmed by XPS. The doped tungsten was present as W5+ in a ratio of 71.5%. In O K-edge XAS spectra, increase in indicated the formation of oxygen vacancies through tungsten doping. The decrease in W 5d-eg peak intensity demonstrated the occupation of the W 5d orbital by electrons formed at the oxygen vacancies. The enrichment of W5+ was owing to transfer of electrons to 5d-eg orbital of tungsten rather than to cerium ions. The acid sites were analysed using FTIR and NH3-TPD. The peak intensity of Brønsted acid sites and amount of NH3 desorption increased from 66.2 to 136.1 µmol g−1 with tungsten doping. The doped tungsten formed Brønsted acid sites and led to enhanced surface acidity and catalytic activity.
{"title":"Electron redistribution and acid site of tungsten-doped CeTiOx with oxygen vacancies","authors":"Myung-Kun Kim, G. Park, Min-Chul Shin, Hong-Dae Kim, Dae-Seung Cho, Heesoo Lee","doi":"10.1080/17436753.2021.1919360","DOIUrl":"https://doi.org/10.1080/17436753.2021.1919360","url":null,"abstract":"ABSTRACT The enhancement of surface acidity for tungsten-doped CeTiOx was investigated through electronic structure. Tungsten doping increased the ratio of Ce3+ from 12.0% to 29.6%, which was confirmed by XPS. The doped tungsten was present as W5+ in a ratio of 71.5%. In O K-edge XAS spectra, increase in indicated the formation of oxygen vacancies through tungsten doping. The decrease in W 5d-eg peak intensity demonstrated the occupation of the W 5d orbital by electrons formed at the oxygen vacancies. The enrichment of W5+ was owing to transfer of electrons to 5d-eg orbital of tungsten rather than to cerium ions. The acid sites were analysed using FTIR and NH3-TPD. The peak intensity of Brønsted acid sites and amount of NH3 desorption increased from 66.2 to 136.1 µmol g−1 with tungsten doping. The doped tungsten formed Brønsted acid sites and led to enhanced surface acidity and catalytic activity.","PeriodicalId":7224,"journal":{"name":"Advances in Applied Ceramics","volume":"47 11 1","pages":"187 - 191"},"PeriodicalIF":2.2,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87526761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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