Pub Date : 1988-11-01DOI: 10.1088/0305-4608/18/11/005
J. H. Sanders, B. Tatarchuk
The use of FeTi as a hydrogen storage material is hindered by surface decomposition of the alloy when exposed to hydrogen charging gases containing PPM levels of O2/H2O impurities. This study investigates the application of palladium coatings as barrier materials against these impurities in order to increase the effective lifetime of the alloy over numerous charge-discharge cycles. Palladium was chosen because it has excellent hydrogen transport properties and it is impermeable to impurities containing oxygen at the temperatures and pressures of interest. Two 10 nm FeTi thin-film specimens were prepared, one coated with an additional 5 nm Pd overlayer, and both samples exposed to identical annealing and reduction treatments. Conversion electron Mossbauer spectroscopy (CEMS) was used along with other analytical techniques (i.e. XPS and SIMS) to obtain chemical, magnetic and electronic information at the buried and exposed interfaces. CEMS demonstrated that the Pd coating prevented subsurface decomposition of FeTi.
{"title":"Protection of FeTi thin films using palladium coatings","authors":"J. H. Sanders, B. Tatarchuk","doi":"10.1088/0305-4608/18/11/005","DOIUrl":"https://doi.org/10.1088/0305-4608/18/11/005","url":null,"abstract":"The use of FeTi as a hydrogen storage material is hindered by surface decomposition of the alloy when exposed to hydrogen charging gases containing PPM levels of O2/H2O impurities. This study investigates the application of palladium coatings as barrier materials against these impurities in order to increase the effective lifetime of the alloy over numerous charge-discharge cycles. Palladium was chosen because it has excellent hydrogen transport properties and it is impermeable to impurities containing oxygen at the temperatures and pressures of interest. Two 10 nm FeTi thin-film specimens were prepared, one coated with an additional 5 nm Pd overlayer, and both samples exposed to identical annealing and reduction treatments. Conversion electron Mossbauer spectroscopy (CEMS) was used along with other analytical techniques (i.e. XPS and SIMS) to obtain chemical, magnetic and electronic information at the buried and exposed interfaces. CEMS demonstrated that the Pd coating prevented subsurface decomposition of FeTi.","PeriodicalId":16828,"journal":{"name":"Journal of Physics F: Metal Physics","volume":"58 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75791483","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 : 1988-11-01DOI: 10.1088/0305-4608/18/11/006
C. Janot, J. Dubois
{"title":"REVIEW ARTICLE: Quasicrystals","authors":"C. Janot, J. Dubois","doi":"10.1088/0305-4608/18/11/006","DOIUrl":"https://doi.org/10.1088/0305-4608/18/11/006","url":null,"abstract":"","PeriodicalId":16828,"journal":{"name":"Journal of Physics F: Metal Physics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90591374","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 : 1988-11-01DOI: 10.1088/0305-4608/18/11/013
T. Itami, M. Shimoji, J. Meijer, W. Lugt
The electrical resistivity rho and the 7Li and 71Ga Knight shifts of liquid Li-Ga alloys were measured. The maximum value of rho on the isotherm at 775 K is 161.1 mu Omega cm at 32.6 at.% Ga. The temperature coefficient delta rho / delta T exhibits a negative minimum at this concentration. This value of rho for liquid Li-Ga alloys does not exceed values appropriate to the nearly free electron (NFE) model; resistivity values calculated by the Faber-Ziman formula are in fair agreement with experiment, though the peak position of the calculated isotherm of rho is shifted slightly to the Li-rich side. However, the experimental Knight shifts provide clear evidence of charge transfer from Li to Ga. The Knight shift KLi of 7Li decreases rapidly with the addition of Ga up to 30 at.% Ga where rho is maximum. Beyond this Ga concentration KLi becomes constant. On the other hand, the Knight shift of 71Ga, KGa, decreases almost linearly with the addition of Li up to 53 at.% Ga. This is attributed to increasing p character of the Ga conduction electrons if 7Li is added. For a more quantitative interpretation it will be necessary to incorporate charge transfer in the NFE model.
{"title":"RESISTIVITY AND KNIGHT-SHIFT OF LIQUID LI-GA ALLOYS","authors":"T. Itami, M. Shimoji, J. Meijer, W. Lugt","doi":"10.1088/0305-4608/18/11/013","DOIUrl":"https://doi.org/10.1088/0305-4608/18/11/013","url":null,"abstract":"The electrical resistivity rho and the 7Li and 71Ga Knight shifts of liquid Li-Ga alloys were measured. The maximum value of rho on the isotherm at 775 K is 161.1 mu Omega cm at 32.6 at.% Ga. The temperature coefficient delta rho / delta T exhibits a negative minimum at this concentration. This value of rho for liquid Li-Ga alloys does not exceed values appropriate to the nearly free electron (NFE) model; resistivity values calculated by the Faber-Ziman formula are in fair agreement with experiment, though the peak position of the calculated isotherm of rho is shifted slightly to the Li-rich side. However, the experimental Knight shifts provide clear evidence of charge transfer from Li to Ga. The Knight shift KLi of 7Li decreases rapidly with the addition of Ga up to 30 at.% Ga where rho is maximum. Beyond this Ga concentration KLi becomes constant. On the other hand, the Knight shift of 71Ga, KGa, decreases almost linearly with the addition of Li up to 53 at.% Ga. This is attributed to increasing p character of the Ga conduction electrons if 7Li is added. For a more quantitative interpretation it will be necessary to incorporate charge transfer in the NFE model.","PeriodicalId":16828,"journal":{"name":"Journal of Physics F: Metal Physics","volume":"2007 1","pages":"2409-2419"},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86209022","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 : 1988-11-01DOI: 10.1088/0305-4608/18/11/004
C. Hidalgo, S. Linderoth
The recovery of Cd deformed at 77 K has been studied by means of positron lifetime measurements. The results are interpreted on the basis of positron trapping and annihilation at jogs.
用正电子寿命测量方法研究了77 K下变形Cd的恢复。这些结果是在正电子捕获和湮灭的基础上解释的。
{"title":"Dislocations in Cd studied by positron annihilation spectroscopy","authors":"C. Hidalgo, S. Linderoth","doi":"10.1088/0305-4608/18/11/004","DOIUrl":"https://doi.org/10.1088/0305-4608/18/11/004","url":null,"abstract":"The recovery of Cd deformed at 77 K has been studied by means of positron lifetime measurements. The results are interpreted on the basis of positron trapping and annihilation at jogs.","PeriodicalId":16828,"journal":{"name":"Journal of Physics F: Metal Physics","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77466978","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 : 1988-11-01DOI: 10.1088/0305-4608/18/11/009
Z. Moser, W. Ga̧sior, N. Gokcen
The partial structure factors of Bhatia and Thorton (BT) (1970), and Faber and Ziman (FZ) (1965), were calculated from critically evaluated thermodynamic equations based on the temperature dependence of enthalpies of formation from previous calorimetric data for liquid Cd-Ga alloys. These equations are compatible with the Cd-Ga phase diagram, and the calculated values of BT partial structure factors are in good agreement with the values obtained from X-ray scattering data.
{"title":"Partial structure factors from thermodynamics and from X-ray scattering for liquid Cd-Ga alloys","authors":"Z. Moser, W. Ga̧sior, N. Gokcen","doi":"10.1088/0305-4608/18/11/009","DOIUrl":"https://doi.org/10.1088/0305-4608/18/11/009","url":null,"abstract":"The partial structure factors of Bhatia and Thorton (BT) (1970), and Faber and Ziman (FZ) (1965), were calculated from critically evaluated thermodynamic equations based on the temperature dependence of enthalpies of formation from previous calorimetric data for liquid Cd-Ga alloys. These equations are compatible with the Cd-Ga phase diagram, and the calculated values of BT partial structure factors are in good agreement with the values obtained from X-ray scattering data.","PeriodicalId":16828,"journal":{"name":"Journal of Physics F: Metal Physics","volume":"142 1","pages":"2363-2369"},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78900012","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}
{"title":"Correlated hyperfine interactions in amorphous Cr72-xFexC17Si8Al3 alloys","authors":"R. Dunlap, D. W. Lawther, P. Hargraves, P. Sinclair","doi":"10.1088/0305-4608/18/11/019","DOIUrl":"https://doi.org/10.1088/0305-4608/18/11/019","url":null,"abstract":"Fully amorphous Cr72-xFexC17Si8Al3 alloys, with 5<or=x<or=40, have been prepared by melt spinning. Room-temperature 57Fe Mossbauer effect spectra of all alloys shown an asymmetric quadrupole split doublet. These results are interpreted in terms of a distribution of Fe probe sites resulting from a distribution of near-neighbour configurations in a dense random packing model.","PeriodicalId":16828,"journal":{"name":"Journal of Physics F: Metal Physics","volume":"27 1","pages":"2479-2486"},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81580996","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 : 1988-11-01DOI: 10.1088/0305-4608/18/11/017
K. Lawniczak-Jablonska, M. Heinonen
The valence band spectra (VBS) of Mo, Ni and MoNi3 alloys were recorded after different surface treatments: (i) after sputtering by 1 keV and 3 keV Ar+ ions, (ii) after annealing at 673 K and (iii) after scraping in situ. In the case of Mo it has been found that contamination of the surface by up to 3 at.% oxygen is responsible for only a small intensity increase on the high energy side, while a carbon concentration of 0.6 at.% plus 3.5 at.% of oxygen smears the fine structure of Mo VBS. After Ar+ ion sputtering and scraping in situ the VBS are almost identical. This indicates that the surface of Mo after Ar+ ion bombardment still has some crystalline order. The photoemission from polycrystalline Mo is determined mainly by the electronic structure of the bulk material and is in good agreement with theoretical predictions. The final-state effect only slightly affected the calculated DOS. This is not valid for the XPVB spectrum of Ni. Sputtering of MoNi3 alloys changes the surface composition and the shape of the valence band. Annealing of the sputtered alloys at 673 K did not restore their initial composition.
{"title":"Influence of sputtering on the valence band of Mo, Ni and MoNi3 alloy","authors":"K. Lawniczak-Jablonska, M. Heinonen","doi":"10.1088/0305-4608/18/11/017","DOIUrl":"https://doi.org/10.1088/0305-4608/18/11/017","url":null,"abstract":"The valence band spectra (VBS) of Mo, Ni and MoNi3 alloys were recorded after different surface treatments: (i) after sputtering by 1 keV and 3 keV Ar+ ions, (ii) after annealing at 673 K and (iii) after scraping in situ. In the case of Mo it has been found that contamination of the surface by up to 3 at.% oxygen is responsible for only a small intensity increase on the high energy side, while a carbon concentration of 0.6 at.% plus 3.5 at.% of oxygen smears the fine structure of Mo VBS. After Ar+ ion sputtering and scraping in situ the VBS are almost identical. This indicates that the surface of Mo after Ar+ ion bombardment still has some crystalline order. The photoemission from polycrystalline Mo is determined mainly by the electronic structure of the bulk material and is in good agreement with theoretical predictions. The final-state effect only slightly affected the calculated DOS. This is not valid for the XPVB spectrum of Ni. Sputtering of MoNi3 alloys changes the surface composition and the shape of the valence band. Annealing of the sputtered alloys at 673 K did not restore their initial composition.","PeriodicalId":16828,"journal":{"name":"Journal of Physics F: Metal Physics","volume":"144 1","pages":"2451-2462"},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78166548","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 : 1988-11-01DOI: 10.1088/0305-4608/18/11/010
Cai Wei-ping
This paper examines the internal friction associated with grain boundaries in aluminium-rare-earth (Al-RE) alloys and develops mathematical expressions for the background and grain-boundary internal friction; suggestions are made as to how the parameters in the expressions can be determined by computer. It is shown that the expressions and computing methods developed are effective and reliable and the results obtained are also satisfactory. Processing the original experimental data on grain-boundary internal friction by the new method is of universal importance in some sense. In determining a series of parameters such as the activation energy, frequency factor, beta 0 and beta H-which are the measurements of the distribution widths of the logarithm of the frequency factor and the activation energy respectively-and the relaxation strength etc., only one original curve is required by the new method. Therefore, the number of times the measurement is repeated can be greatly reduced, saving time and effort, and full use can be made of the experimental data.
{"title":"Accurate determination of the parameters of internal friction associated with a grain boundary","authors":"Cai Wei-ping","doi":"10.1088/0305-4608/18/11/010","DOIUrl":"https://doi.org/10.1088/0305-4608/18/11/010","url":null,"abstract":"This paper examines the internal friction associated with grain boundaries in aluminium-rare-earth (Al-RE) alloys and develops mathematical expressions for the background and grain-boundary internal friction; suggestions are made as to how the parameters in the expressions can be determined by computer. It is shown that the expressions and computing methods developed are effective and reliable and the results obtained are also satisfactory. Processing the original experimental data on grain-boundary internal friction by the new method is of universal importance in some sense. In determining a series of parameters such as the activation energy, frequency factor, beta 0 and beta H-which are the measurements of the distribution widths of the logarithm of the frequency factor and the activation energy respectively-and the relaxation strength etc., only one original curve is required by the new method. Therefore, the number of times the measurement is repeated can be greatly reduced, saving time and effort, and full use can be made of the experimental data.","PeriodicalId":16828,"journal":{"name":"Journal of Physics F: Metal Physics","volume":"87 1","pages":"2371-2380"},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85475706","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 : 1988-10-01DOI: 10.1088/0305-4608/18/10/009
Horst Rakel, C. Falter, W. Ludwig
A recently proposed theory of quasi-ions is demonstrated using sodium as an example. In this theory the total electronic charge density is decomposed in 'partial densities', which can unambiguously be assigned to individual atoms or sublattices. The partial densities together with the ion cores constitute the new building blocks (quasi-ions) into which the crystal can be decomposed. For the study of the dynamics of the crystal lattice the phonon-induced charge density variation is split up in one part that rigidly followed the motion of the ions and a second part which is due to distortions during that motion. The effects of both contributions on the phonon dispersion are investigated using special models for the distortions. Introducing small inhomegeneities to the spherical Na quasi-ions the authors further analyse the influence of such charge redistributions on the phonon dispersion. They show that the distortion part of the charge density variation leads to characteristic anomalous structures in the dispersion curves, which are rather similar to those occurring in d-electron metals.
{"title":"Partial density approach to lattice dynamics of metals","authors":"Horst Rakel, C. Falter, W. Ludwig","doi":"10.1088/0305-4608/18/10/009","DOIUrl":"https://doi.org/10.1088/0305-4608/18/10/009","url":null,"abstract":"A recently proposed theory of quasi-ions is demonstrated using sodium as an example. In this theory the total electronic charge density is decomposed in 'partial densities', which can unambiguously be assigned to individual atoms or sublattices. The partial densities together with the ion cores constitute the new building blocks (quasi-ions) into which the crystal can be decomposed. For the study of the dynamics of the crystal lattice the phonon-induced charge density variation is split up in one part that rigidly followed the motion of the ions and a second part which is due to distortions during that motion. The effects of both contributions on the phonon dispersion are investigated using special models for the distortions. Introducing small inhomegeneities to the spherical Na quasi-ions the authors further analyse the influence of such charge redistributions on the phonon dispersion. They show that the distortion part of the charge density variation leads to characteristic anomalous structures in the dispersion curves, which are rather similar to those occurring in d-electron metals.","PeriodicalId":16828,"journal":{"name":"Journal of Physics F: Metal Physics","volume":"50 1","pages":"2181-2193"},"PeriodicalIF":0.0,"publicationDate":"1988-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78955832","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 : 1988-10-01DOI: 10.1088/0305-4608/18/10/005
M. Krajčí, P. Mrafko
A simple approach to the computer simulation of the atomic structure and the calculation of the electronic structure of the amorphous metallic alloy Fe100-xBx is presented. The structural models are constructed by the classical thermodynamic simulation methods. The electronic states are described by a simple tight-binding Hamiltonian, with matrix elements calculated according to the Harrison parametrisation. The electronic structure is calculated by the recursion method. Problems in the use of the method are discussed. The results are compared with the results of more sophisticated approaches and with an experiment.
{"title":"Computer simulation of amorphous alloy Fe100-xBx, x=14-25","authors":"M. Krajčí, P. Mrafko","doi":"10.1088/0305-4608/18/10/005","DOIUrl":"https://doi.org/10.1088/0305-4608/18/10/005","url":null,"abstract":"A simple approach to the computer simulation of the atomic structure and the calculation of the electronic structure of the amorphous metallic alloy Fe100-xBx is presented. The structural models are constructed by the classical thermodynamic simulation methods. The electronic states are described by a simple tight-binding Hamiltonian, with matrix elements calculated according to the Harrison parametrisation. The electronic structure is calculated by the recursion method. Problems in the use of the method are discussed. The results are compared with the results of more sophisticated approaches and with an experiment.","PeriodicalId":16828,"journal":{"name":"Journal of Physics F: Metal Physics","volume":"38 1","pages":"2137-2147"},"PeriodicalIF":0.0,"publicationDate":"1988-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81294139","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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