Pub Date : 2019-01-23DOI: 10.5772/INTECHOPEN.79170
Shobit Omar
Lower valent cation-doped CeO 2 materials have attracted remarkable research interest for the electrolyte application in solid oxide fuel cells operating in the intermediate temperature range (500–700°C). At these temperatures, the oxygen-ion conductivity of gad- olinium-doped ceria is about an order of magnitude higher than that of yttria-stabilized zirconia. The oxygen-ion diffusion in the cubic fluorite structure of CeO 2 is dependent on several factors such as charge valence and size of dopant cation, doping amount, etc. In the literature, several conductivity trends have been reported as a function of these parameters and are explained by the atomistic computational models. This chapter describes the highlights of the various activities that have been done in this regard to provide insights into the mechanisms underlying the oxygen-ion conduction process in acceptor-doped ceria. the concept of critical ionic radius alone cannot explain the maximum oxygen-ion conductivity observed in Pm 3+ -doped CeO 2 as found by the first-principles density functional theory calculations. Particular attention has been to a more recent atomistic simulations study on rare-earth-doped ceria which calculates the migration energies for all the possible jump configu rations that may present in rare-earth-doped CeO 2 . This study explains the importance of the shape of migration energy barrier and its impact on the ionic conductivity.
{"title":"Doped Ceria for Solid Oxide Fuel Cells","authors":"Shobit Omar","doi":"10.5772/INTECHOPEN.79170","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.79170","url":null,"abstract":"Lower valent cation-doped CeO 2 materials have attracted remarkable research interest for the electrolyte application in solid oxide fuel cells operating in the intermediate temperature range (500–700°C). At these temperatures, the oxygen-ion conductivity of gad- olinium-doped ceria is about an order of magnitude higher than that of yttria-stabilized zirconia. The oxygen-ion diffusion in the cubic fluorite structure of CeO 2 is dependent on several factors such as charge valence and size of dopant cation, doping amount, etc. In the literature, several conductivity trends have been reported as a function of these parameters and are explained by the atomistic computational models. This chapter describes the highlights of the various activities that have been done in this regard to provide insights into the mechanisms underlying the oxygen-ion conduction process in acceptor-doped ceria. the concept of critical ionic radius alone cannot explain the maximum oxygen-ion conductivity observed in Pm 3+ -doped CeO 2 as found by the first-principles density functional theory calculations. Particular attention has been to a more recent atomistic simulations study on rare-earth-doped ceria which calculates the migration energies for all the possible jump configu rations that may present in rare-earth-doped CeO 2 . This study explains the importance of the shape of migration energy barrier and its impact on the ionic conductivity.","PeriodicalId":9745,"journal":{"name":"Cerium Oxide - Applications and Attributes","volume":"92 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80459661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-28DOI: 10.5772/INTECHOPEN.82757
Sher Bahadar Khan, K. Akhtar
{"title":"Introductory Chapter: Cerium Oxide - Applications and Attributes","authors":"Sher Bahadar Khan, K. Akhtar","doi":"10.5772/INTECHOPEN.82757","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.82757","url":null,"abstract":"","PeriodicalId":9745,"journal":{"name":"Cerium Oxide - Applications and Attributes","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91278006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-05DOI: 10.5772/INTECHOPEN.79329
A. P. Loperena, I. L. Lehr, S. Saidman
Die-cast AZ91D magnesium alloy (8.9 wt.% Al, 0.6 wt.% Zn, 0.2 wt.% Mn, and balance Mg), as novel alternative biodegradable material, has received great attention due to their potential use in biomedical implants. However, their poor corrosion resistance in physiological fluids restricts practical applications. Cerium-based coatings have been studied as an environmental friendly option to enhance the corrosion resistance of magnesium alloys. In order to control the biodegradation rate of AZ91D magnesium alloy in simulated physiological solution, the formation of a coating from a solution containing cerium nitrate (Ce(NO 3 ) 3 ) was studied. The effect of different additives in the treatment solution (ascorbic acid, citric acid, and sodium citrate) on the anticorrosive properties of the coatings was evaluated. The characterization of the coatings was done using electrochemical techniques and SEM/EDS, XRD, and XPS analyses. The corrosion properties were examined in Ringer solution by polarization studies, open circuit measurements, and faradaic impedance spectroscopy. Results showed that the incorporation of additives improves the anticorrosive properties of the Ce-based film. The coating modified with ascorbic acid provides the best corrosion resistance. According to XPS results, the film is mainly composed by Mg oxides or hydroxides and Ce oxides.
{"title":"Cerium Oxides for Corrosion Protection of AZ91D Mg Alloy","authors":"A. P. Loperena, I. L. Lehr, S. Saidman","doi":"10.5772/INTECHOPEN.79329","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.79329","url":null,"abstract":"Die-cast AZ91D magnesium alloy (8.9 wt.% Al, 0.6 wt.% Zn, 0.2 wt.% Mn, and balance Mg), as novel alternative biodegradable material, has received great attention due to their potential use in biomedical implants. However, their poor corrosion resistance in physiological fluids restricts practical applications. Cerium-based coatings have been studied as an environmental friendly option to enhance the corrosion resistance of magnesium alloys. In order to control the biodegradation rate of AZ91D magnesium alloy in simulated physiological solution, the formation of a coating from a solution containing cerium nitrate (Ce(NO 3 ) 3 ) was studied. The effect of different additives in the treatment solution (ascorbic acid, citric acid, and sodium citrate) on the anticorrosive properties of the coatings was evaluated. The characterization of the coatings was done using electrochemical techniques and SEM/EDS, XRD, and XPS analyses. The corrosion properties were examined in Ringer solution by polarization studies, open circuit measurements, and faradaic impedance spectroscopy. Results showed that the incorporation of additives improves the anticorrosive properties of the Ce-based film. The coating modified with ascorbic acid provides the best corrosion resistance. According to XPS results, the film is mainly composed by Mg oxides or hydroxides and Ce oxides.","PeriodicalId":9745,"journal":{"name":"Cerium Oxide - Applications and Attributes","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72840183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-07DOI: 10.5772/INTECHOPEN.80801
L. Pîslaru-Dănescu, G. Ţelipan, I. Ion, VirgilMarinescu
In this chapter, two important aspects of using CeO2 in the field of gas sensors are presented. Firstly, for CO2 detection in the range of 0–5000 ppm, a binary semiconductor oxides CeO2-Y2O3 was used. Secondly, as a dopants, in oxide semiconductor systems, used to detect the NO2. In this case, CeO2 is used as a dopant in hybride composite, consisting of reduced graphene oxide/ZnO, in order to increase the sensibility in NO2 detection at low concentration in the range of 0–10 ppm. The structural and morphological characterization of sensitive materials by X-ray diffraction, SEM, adsorption desorption isotherms, thermal analysis and RAMAN spectroscopy are presented. Also, the sensing element of the sensor that detects the NO2 is achieved by depositing the nanocomposite material on the interdigital grid. The electronic conditioning signal from the sensing element is achieved by using a Wheatstone bridge together with an instrumentation operational amplifier.
{"title":"Prototyping a Gas Sensors Using CeO2 as a Matrix or Dopant in Oxide Semiconductor Systems","authors":"L. Pîslaru-Dănescu, G. Ţelipan, I. Ion, VirgilMarinescu","doi":"10.5772/INTECHOPEN.80801","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.80801","url":null,"abstract":"In this chapter, two important aspects of using CeO2 in the field of gas sensors are presented. Firstly, for CO2 detection in the range of 0–5000 ppm, a binary semiconductor oxides CeO2-Y2O3 was used. Secondly, as a dopants, in oxide semiconductor systems, used to detect the NO2. In this case, CeO2 is used as a dopant in hybride composite, consisting of reduced graphene oxide/ZnO, in order to increase the sensibility in NO2 detection at low concentration in the range of 0–10 ppm. The structural and morphological characterization of sensitive materials by X-ray diffraction, SEM, adsorption desorption isotherms, thermal analysis and RAMAN spectroscopy are presented. Also, the sensing element of the sensor that detects the NO2 is achieved by depositing the nanocomposite material on the interdigital grid. The electronic conditioning signal from the sensing element is achieved by using a Wheatstone bridge together with an instrumentation operational amplifier.","PeriodicalId":9745,"journal":{"name":"Cerium Oxide - Applications and Attributes","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88901114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-05DOI: 10.5772/INTECHOPEN.81332
Miren Aguirre, M. Paulis, J. R. Leiza
The encapsulation of inorganic nanoparticles into polymer particles opens the door to countless applications taking advantage of the properties of both phases. In this chapter the UV absorbing capacity of CeO 2 nanoparticles and the film forming capacity of acrylic polymers are combined. A synthetic route to produce waterborne acrylic/CeO 2 hybrid nanocomposites for UV absorbing coatings applications is presented. This strategy leads to encapsulated morphology of the CeO 2 nanoparticles into the polymer particles and therefore to the lack of agglomeration during film formation. A mathematical model developed for inorganic/organic hybrid systems is able to explain the morphology evolution from the initial monomer droplet to the polymer particles. The films cast from these latexes are transparent and show excellent UV absorption that increases with the amount of cerium oxide nanoparticles in the hybrid latex. Finally, the photoactivity behavior that the CeO 2 nanoparticles may have on the polymeric matrix is studied, discarding addi- tional effects on the acrylic polymer matrix.
{"title":"Waterborne Acrylic/CeO2 Nanocomposites for UV Blocking Clear Coats","authors":"Miren Aguirre, M. Paulis, J. R. Leiza","doi":"10.5772/INTECHOPEN.81332","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.81332","url":null,"abstract":"The encapsulation of inorganic nanoparticles into polymer particles opens the door to countless applications taking advantage of the properties of both phases. In this chapter the UV absorbing capacity of CeO 2 nanoparticles and the film forming capacity of acrylic polymers are combined. A synthetic route to produce waterborne acrylic/CeO 2 hybrid nanocomposites for UV absorbing coatings applications is presented. This strategy leads to encapsulated morphology of the CeO 2 nanoparticles into the polymer particles and therefore to the lack of agglomeration during film formation. A mathematical model developed for inorganic/organic hybrid systems is able to explain the morphology evolution from the initial monomer droplet to the polymer particles. The films cast from these latexes are transparent and show excellent UV absorption that increases with the amount of cerium oxide nanoparticles in the hybrid latex. Finally, the photoactivity behavior that the CeO 2 nanoparticles may have on the polymeric matrix is studied, discarding addi- tional effects on the acrylic polymer matrix.","PeriodicalId":9745,"journal":{"name":"Cerium Oxide - Applications and Attributes","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81959678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-05DOI: 10.5772/INTECHOPEN.79225
Kai Li, Ji Chen, Dan Zou
Rare earth elements are widely found in many minerals, some of which, such as bastn- aesite, monazite, and xenotime, are of great commercial value. Cerium (Ce) is the rare earth element with the highest content in light rare earth ore. Solvent extraction is the most effective and efficient method to recover and separate Ce from other light rare earth elements. After acid leaching of rare earth minerals, leaching solution was obtained, and cerium oxide of products of high purity was obtained by extraction and stripping. It is well known that Ce(IV) can be easily separated from the other RE(III) by adopting the traditional solvent extraction. Based on this principle, the clean process of oxidation roast ing and Ce(IV) separation for Sichuan bastnaesite was developed. And then, a preliminary flow sheet of two-step oxidation and extraction of Ce(IV) for Bayan Obo mixed rare earth ores was further proposed. Sulfuric acid rare earth solution containing Ce(IV) → reduces Ce 4+ to form Ce 3+ → NaOH base decomposition → HCl solubilization → Oxalic acid precipitation → Calcination.
{"title":"Extraction and Recovery of Cerium from Rare Earth Ore by Solvent Extraction","authors":"Kai Li, Ji Chen, Dan Zou","doi":"10.5772/INTECHOPEN.79225","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.79225","url":null,"abstract":"Rare earth elements are widely found in many minerals, some of which, such as bastn- aesite, monazite, and xenotime, are of great commercial value. Cerium (Ce) is the rare earth element with the highest content in light rare earth ore. Solvent extraction is the most effective and efficient method to recover and separate Ce from other light rare earth elements. After acid leaching of rare earth minerals, leaching solution was obtained, and cerium oxide of products of high purity was obtained by extraction and stripping. It is well known that Ce(IV) can be easily separated from the other RE(III) by adopting the traditional solvent extraction. Based on this principle, the clean process of oxidation roast ing and Ce(IV) separation for Sichuan bastnaesite was developed. And then, a preliminary flow sheet of two-step oxidation and extraction of Ce(IV) for Bayan Obo mixed rare earth ores was further proposed. Sulfuric acid rare earth solution containing Ce(IV) → reduces Ce 4+ to form Ce 3+ → NaOH base decomposition → HCl solubilization → Oxalic acid precipitation → Calcination.","PeriodicalId":9745,"journal":{"name":"Cerium Oxide - Applications and Attributes","volume":"2016 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73755324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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