Pub Date : 2002-12-01DOI: 10.2320/MATERTRANS.43.3146
Y. Takada, Shi-Duk Lim, K. Asami, K. Kim, O. Okuno
Galvanic corrosion between dental amalgams and titanium was examined in terms of released ions. The ions released from the dental amalgams in contact with titanium at surface area ratios of titanium/amalgam in a range of 1/10-10/1 were quantitatively analyzed after being immersed in 0.9mass% sodium chloride solution at 310K for 6.05 x 10 5 s. The potentials and the anodic polarization curves were also measured under the same conditions. Furthermore, the amalgam surfaces after immersion were analyzed using WDS. Each potential of the conventional amalgams was always lower than that of titanium, though each potential of the high-copper amalgam was reversed in the early stage of immersion and was also lower. When the surface area ratio did not increase to over 1/1, each total amount of ions released from the amalgams in contact with titanium was a little larger or smaller than that released from amalgams not in contact with titanium. However, tin and copper ions released from the conventional amalgams and the high-copper amalgam, respectively, increased greatly when the ratio grew to 10/1. Each amount of released ions with titanium, except mercury ions, was approximated by the equation W with = a x (W without ) b , where the coefficients a and b are constant and W with and W without mean each amount of the released ions with and without titanium, respectively. The coefficient b probably relied on the surface area ratio and immersion time. When the ratio grew to 10/1, the amount of released ions with titanium, except mercury ions, could be shown by the equation W with = a x (W without ) at a = 4.202-9.982. Since the contact with titanium seemed to drastically make the amount of mercury ions decrease, the mercury ions did not fit this equation. These results indicated a risk of galvanic corrosion between dental amalgams and titanium with a large surface area ratio.
从释放离子的角度研究了牙科汞合金与钛之间的电偶腐蚀。在质量分数为0.9 %的氯化钠溶液中浸泡6.05 x 10.5 s后，定量分析钛与牙汞合金在钛/汞合金表面积比为1/10 ~ 10/1范围内接触钛时所释放的离子。测定了在相同条件下的电势和阳极极化曲线。此外，用WDS对浸渍后的汞合金表面进行了分析。常规汞合金的各电势始终低于钛合金，而高铜汞合金的各电势在浸渍初期相反，也低于钛合金。当表面积比未增加到1/1以上时，与钛接触的汞合金释放的各离子总量均略大于或小于未与钛接触的汞合金释放的离子总量。而当比例增加到10/1时，普通汞合金和高铜汞合金释放的锡离子和铜离子均显著增加。除汞离子外，各含钛离子的释放量均近似为公式W with = a x (W without) b，其中系数a和b为常数，W with和W without分别表示含钛离子和不含钛离子的释放量。系数b可能取决于表面积比和浸泡时间。当比例增大到10/1时，在a = 4.202 ~ 9.982时，除汞离子外，有钛的离子的释放量可以用方程W with = a x (W without)表示。由于与钛的接触似乎使汞离子的数量急剧减少，所以汞离子不符合这个方程。这些结果表明，大表面积比的牙科汞合金与钛之间存在电偶腐蚀的风险。
{"title":"Galvanic corrosion of dental amalgams in contact with titanium in terms of released ions : Biomaterials and bioengineering","authors":"Y. Takada, Shi-Duk Lim, K. Asami, K. Kim, O. Okuno","doi":"10.2320/MATERTRANS.43.3146","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.3146","url":null,"abstract":"Galvanic corrosion between dental amalgams and titanium was examined in terms of released ions. The ions released from the dental amalgams in contact with titanium at surface area ratios of titanium/amalgam in a range of 1/10-10/1 were quantitatively analyzed after being immersed in 0.9mass% sodium chloride solution at 310K for 6.05 x 10 5 s. The potentials and the anodic polarization curves were also measured under the same conditions. Furthermore, the amalgam surfaces after immersion were analyzed using WDS. Each potential of the conventional amalgams was always lower than that of titanium, though each potential of the high-copper amalgam was reversed in the early stage of immersion and was also lower. When the surface area ratio did not increase to over 1/1, each total amount of ions released from the amalgams in contact with titanium was a little larger or smaller than that released from amalgams not in contact with titanium. However, tin and copper ions released from the conventional amalgams and the high-copper amalgam, respectively, increased greatly when the ratio grew to 10/1. Each amount of released ions with titanium, except mercury ions, was approximated by the equation W with = a x (W without ) b , where the coefficients a and b are constant and W with and W without mean each amount of the released ions with and without titanium, respectively. The coefficient b probably relied on the surface area ratio and immersion time. When the ratio grew to 10/1, the amount of released ions with titanium, except mercury ions, could be shown by the equation W with = a x (W without ) at a = 4.202-9.982. Since the contact with titanium seemed to drastically make the amount of mercury ions decrease, the mercury ions did not fit this equation. These results indicated a risk of galvanic corrosion between dental amalgams and titanium with a large surface area ratio.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"11 1","pages":"3146-3154"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82591632","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 : 2002-12-01DOI: 10.2320/MATERTRANS.43.3010
M. Okido, K. Nishikawa, K. Kuroda, R. Ichino, Zhongwei Zhao, O. Takai
A titanium substrate was coated with a hydroxyapatite (HA) film under a cathodic potential in aqueous solutions containing calcium and phosphate ions and hydrogen peroxide at pH 5.5 and a temperature of 309.5 K. The deposition process was monitored using the current density change, and the mass change was measured using the electrochemical quartz crystal microbalance (QCM) technique at cathodic potentials, and compared with deposition on a gold substrate. The deposits were analyzed using X-ray diffraction and scanning electron microscopy. HA films were obtained at different cathodic potentials, and the film morphology changed with the potential. With electrolysis at -557 mV, HA was deposited and accumulated after 800 s, when the mass gain increased significantly, as determined using QCM. After 800 s, the cathodic current increased and then decreased with HA growth. The HA film was porous, with pores several hundred nanometers in size, and formed a network of aggregates with walls about 50 nm thick. The filling factor was about 59 vol%, as evaluated from the mass gain using QCM and microscopic observation.
{"title":"Evaluation of the hydroxyapatite film coating on titanium cathode by QCM : Biomaterials and bioengineering","authors":"M. Okido, K. Nishikawa, K. Kuroda, R. Ichino, Zhongwei Zhao, O. Takai","doi":"10.2320/MATERTRANS.43.3010","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.3010","url":null,"abstract":"A titanium substrate was coated with a hydroxyapatite (HA) film under a cathodic potential in aqueous solutions containing calcium and phosphate ions and hydrogen peroxide at pH 5.5 and a temperature of 309.5 K. The deposition process was monitored using the current density change, and the mass change was measured using the electrochemical quartz crystal microbalance (QCM) technique at cathodic potentials, and compared with deposition on a gold substrate. The deposits were analyzed using X-ray diffraction and scanning electron microscopy. HA films were obtained at different cathodic potentials, and the film morphology changed with the potential. With electrolysis at -557 mV, HA was deposited and accumulated after 800 s, when the mass gain increased significantly, as determined using QCM. After 800 s, the cathodic current increased and then decreased with HA growth. The HA film was porous, with pores several hundred nanometers in size, and formed a network of aggregates with walls about 50 nm thick. The filling factor was about 59 vol%, as evaluated from the mass gain using QCM and microscopic observation.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"5 1","pages":"3010-3014"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82552981","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 : 2002-10-01DOI: 10.2320/MATERTRANS.43.2455
T. Furuhara, E. Sato, T. Mizoguchi, Shuji Furimoto, T. Maki
The characteristics and superplasticity of the (a + θ) microduplex structures formed by various thermomechanical processings were studied in an ultra-high carbon steel (Fe-1.4Cr-1.0C). After heavy warm rolling of pearlite, an (a + θ) microduplex structure with equi-axed a grains of 0.4 pm in diameter and spheroidized θ particles of 0.2 μm in diameter is obtained. The a matrix exhibits a recovered structure in which most of a grain boundaries are low-angle boundaries, resulting in rather smaller elongation at 973 K. Heavy cold rolling and annealing of pearlite produces an (a + θ) microduplex structure which consists of the coarse-grain region (d α ∼ 0.4 μm) with high-angle a boundaries and the fine-grain region (d α ∼ 0.2 μm) with low-angle a boundaries. Superplasticity in this specimen is slightly better than the warm-rolled specimen. When pearlite was austenitized in the (y + θ) region, quenched and tempered at the temperature below A 1 , an (a + θ) microduplex structure in which a and θ grain sizes are nearly the same as in the warm-rolled specimen and most of a boundaries are of high-angle one is formed. Such ultra-fine a grains are formed through the recovery of the fine (a' lath martensite + θ) mixture during tempering. This microduplex structure exhibits superior superplasticity. Heavy warm rolling prior to the quenching and tempering improves total elongation further because the distribution of prior y grain size is more uniform. When cold-rolled pearlite was austenitized and air-cooled, an (a + θ) microduplex structure with high-angle a boundary is formed. However, since the a grain size was relatively large (ca. 2 μm), its superplastic performance is poor. Finally, more simplification of processing for superplasticity was attempted. Further improvement of superplasticity was achieved by omitting the tempering in the quenching and tempering treatment.
{"title":"Grain boundary character and superplasticity of fine-grained ultra-high carbon steel : Superplasticity and its applications","authors":"T. Furuhara, E. Sato, T. Mizoguchi, Shuji Furimoto, T. Maki","doi":"10.2320/MATERTRANS.43.2455","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.2455","url":null,"abstract":"The characteristics and superplasticity of the (a + θ) microduplex structures formed by various thermomechanical processings were studied in an ultra-high carbon steel (Fe-1.4Cr-1.0C). After heavy warm rolling of pearlite, an (a + θ) microduplex structure with equi-axed a grains of 0.4 pm in diameter and spheroidized θ particles of 0.2 μm in diameter is obtained. The a matrix exhibits a recovered structure in which most of a grain boundaries are low-angle boundaries, resulting in rather smaller elongation at 973 K. Heavy cold rolling and annealing of pearlite produces an (a + θ) microduplex structure which consists of the coarse-grain region (d α ∼ 0.4 μm) with high-angle a boundaries and the fine-grain region (d α ∼ 0.2 μm) with low-angle a boundaries. Superplasticity in this specimen is slightly better than the warm-rolled specimen. When pearlite was austenitized in the (y + θ) region, quenched and tempered at the temperature below A 1 , an (a + θ) microduplex structure in which a and θ grain sizes are nearly the same as in the warm-rolled specimen and most of a boundaries are of high-angle one is formed. Such ultra-fine a grains are formed through the recovery of the fine (a' lath martensite + θ) mixture during tempering. This microduplex structure exhibits superior superplasticity. Heavy warm rolling prior to the quenching and tempering improves total elongation further because the distribution of prior y grain size is more uniform. When cold-rolled pearlite was austenitized and air-cooled, an (a + θ) microduplex structure with high-angle a boundary is formed. However, since the a grain size was relatively large (ca. 2 μm), its superplastic performance is poor. Finally, more simplification of processing for superplasticity was attempted. Further improvement of superplasticity was achieved by omitting the tempering in the quenching and tempering treatment.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"16 1","pages":"2455-2462"},"PeriodicalIF":0.0,"publicationDate":"2002-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74470570","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 : 2002-08-01DOI: 10.2320/MATERTRANS.43.2050
K. Shimizu
Microstructures in martensites and effects of uniaxial stress, magnetic field and hydrostatic pressure on martensitic transformations, which were investigated by the author, are briefly summarized. Unsolved problems related to this investigation are pointed out and some ideas are proposed to solve the problems. Interactions between lattices and electrons should be clarified in order to establish the cause of martensitic transformation. In particular, the exact electronic band structure at Brillouin zone boundaries should be delineated, and whether martensitic nuclei are indeed grown from precursory strained regions in matrix phases should be clarified. How the precursory strained region is related to the lattice invariant strain considered in the phenomenological crystallographic theory for martensitic transformations and actually observed by TEM should also be clarified. Some other future research subjects, such as the effects of uniaxial stress, magnetic field and hydrostatic pressure on martensitic transformations, and various related functions, such as shape memory effect and superelasticity, are further pointed out.
{"title":"Martensitic Transformations : Microstructures and Uniaxial Stress, Magnetic Field and Hydrostatic Pressure Effects","authors":"K. Shimizu","doi":"10.2320/MATERTRANS.43.2050","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.2050","url":null,"abstract":"Microstructures in martensites and effects of uniaxial stress, magnetic field and hydrostatic pressure on martensitic transformations, which were investigated by the author, are briefly summarized. Unsolved problems related to this investigation are pointed out and some ideas are proposed to solve the problems. Interactions between lattices and electrons should be clarified in order to establish the cause of martensitic transformation. In particular, the exact electronic band structure at Brillouin zone boundaries should be delineated, and whether martensitic nuclei are indeed grown from precursory strained regions in matrix phases should be clarified. How the precursory strained region is related to the lattice invariant strain considered in the phenomenological crystallographic theory for martensitic transformations and actually observed by TEM should also be clarified. Some other future research subjects, such as the effects of uniaxial stress, magnetic field and hydrostatic pressure on martensitic transformations, and various related functions, such as shape memory effect and superelasticity, are further pointed out.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"29 1","pages":"2050-2057"},"PeriodicalIF":0.0,"publicationDate":"2002-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89934799","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 : 2002-08-01DOI: 10.2320/MATERTRANS.43.1784
T. Takemoto, Tatsuya Funaki
The role of the electrochemical reaction between solder and copper base metal in soldering flux was investigated in relation to wetting. The research includes the contact polarization between solder and base metal in soldering flux of RA type. The difference of electrode potential between solder and base metal in soldering flux plays an important role in removing the oxide film by contact polarization. It is concluded that the electrode potential of Sn-based lead-free solders should be significantly lower than copper to obtain good wettability, because the accelerated anodic dissolution of tin by contacting with the copper base metal enhances the wettability by the removal of tin oxide which is one of the stable oxide on base metal and solder. Sn-Pb has the adequate electrode potential to be effectively dissolved when contacted by copper. On the other hand, the electrode potential of Sn-3.5Ag is very close to copper: the condition gives extremely small contact current. The addition of less noble elements that can lower the electrode potential is effective to enhance the wettability of Sn-3.5Ag. Sn-Zn solder has extremely low electrode potential than a copper base metal; the situation excessively accelerates the preferential anodic dissolution of zinc resulting in the no dissolution of tin. The addition of lead to Sn-3.5Ag solder lowered the electrode potential, which increased the potential difference between solder and copper base metal, as a result the contact current between them was increased. The improved wettability is confirmed by adding lead to Sn-3.5Ag; all lead added solders showed a larger spread area, i.e., a smaller contact angle than Sn-3.5Ag after the spreading test. This work proposed the role of electrochemistry in wetting based on the potential difference between base metal and solder including the degree of contact corrosion current between them.
{"title":"Role of electrode potential difference between lead-free solder and copper base metal in wetting : Lead-free electronics packaging","authors":"T. Takemoto, Tatsuya Funaki","doi":"10.2320/MATERTRANS.43.1784","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.1784","url":null,"abstract":"The role of the electrochemical reaction between solder and copper base metal in soldering flux was investigated in relation to wetting. The research includes the contact polarization between solder and base metal in soldering flux of RA type. The difference of electrode potential between solder and base metal in soldering flux plays an important role in removing the oxide film by contact polarization. It is concluded that the electrode potential of Sn-based lead-free solders should be significantly lower than copper to obtain good wettability, because the accelerated anodic dissolution of tin by contacting with the copper base metal enhances the wettability by the removal of tin oxide which is one of the stable oxide on base metal and solder. Sn-Pb has the adequate electrode potential to be effectively dissolved when contacted by copper. On the other hand, the electrode potential of Sn-3.5Ag is very close to copper: the condition gives extremely small contact current. The addition of less noble elements that can lower the electrode potential is effective to enhance the wettability of Sn-3.5Ag. Sn-Zn solder has extremely low electrode potential than a copper base metal; the situation excessively accelerates the preferential anodic dissolution of zinc resulting in the no dissolution of tin. The addition of lead to Sn-3.5Ag solder lowered the electrode potential, which increased the potential difference between solder and copper base metal, as a result the contact current between them was increased. The improved wettability is confirmed by adding lead to Sn-3.5Ag; all lead added solders showed a larger spread area, i.e., a smaller contact angle than Sn-3.5Ag after the spreading test. This work proposed the role of electrochemistry in wetting based on the potential difference between base metal and solder including the degree of contact corrosion current between them.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"74 1","pages":"1784-1790"},"PeriodicalIF":0.0,"publicationDate":"2002-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85895977","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 : 2002-08-01DOI: 10.2320/MATERTRANS.43.1918
Takahiro Nakamura, H. Koshiba, M. Imafuku, A. Inoue, E. Matsubara
The primary metastable phase in the Fe 70 Nb 10 B 20 amorphous alloy is the complex fcc Fe 23 B 6 phase with a large lattice parameter. The atomic site of Nb atoms in this metastable phase was determined by the anomalous X-ray scattering (AXS) method. Nb atoms in the metastable phase located at the similar position expected in the local structural unit in the amorphous state. Thus, the precipitation of the metastable phase does not require long-distance diffusion of Nb atoms in the amorphous matrix.
{"title":"Determination of atomic sites of Nb dissolved in metastable Fe23B6 phase : Bulk amorphous, nano-crystalline and nano-quasicrystalline alloys IV","authors":"Takahiro Nakamura, H. Koshiba, M. Imafuku, A. Inoue, E. Matsubara","doi":"10.2320/MATERTRANS.43.1918","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.1918","url":null,"abstract":"The primary metastable phase in the Fe 70 Nb 10 B 20 amorphous alloy is the complex fcc Fe 23 B 6 phase with a large lattice parameter. The atomic site of Nb atoms in this metastable phase was determined by the anomalous X-ray scattering (AXS) method. Nb atoms in the metastable phase located at the similar position expected in the local structural unit in the amorphous state. Thus, the precipitation of the metastable phase does not require long-distance diffusion of Nb atoms in the amorphous matrix.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"27 1","pages":"1918-1920"},"PeriodicalIF":0.0,"publicationDate":"2002-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73389805","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 : 2002-07-01DOI: 10.2320/MATERTRANS.43.1624
S. Konishi, M. Moriyama, M. Murakami
In order to understand the void formation mechanism in electroplated Cu interconnects used in Si-semiconductor devices, microstructure of Cu/CuO/Cu layered films which were prepared on the Si 3 N 4 /Si substrates by the sputter-deposition technique was observed by transmission electron microscopy (TEM) and scanning ion microscopy (SIM). A high density of macro and micro voids were observed in the samples annealed in atmosphere containing hydrogen, whereas no voids were observed in the samples annealed in Ar atmosphere. TEM observation suggested that a small amount of oxygen contained in the Cu films (even a native oxide layer) formed water vapor at elevated temperatures, causing formation of the micro-voids when the samples were annealed in hydrogen atmosphere. The present result suggested that the void formation in the electroplated Cu films was induced by existence of impurities such as oxygen in the Cu films, and that the void growth was strongly enhanced by annealing in hydrogen atmosphere.
{"title":"Effect of annealing atmosphere on void formation in copper interconnects : Special issue on materials-related issues for Cu interconnects used in ultra high speed large scaled integrated Si devices","authors":"S. Konishi, M. Moriyama, M. Murakami","doi":"10.2320/MATERTRANS.43.1624","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.1624","url":null,"abstract":"In order to understand the void formation mechanism in electroplated Cu interconnects used in Si-semiconductor devices, microstructure of Cu/CuO/Cu layered films which were prepared on the Si 3 N 4 /Si substrates by the sputter-deposition technique was observed by transmission electron microscopy (TEM) and scanning ion microscopy (SIM). A high density of macro and micro voids were observed in the samples annealed in atmosphere containing hydrogen, whereas no voids were observed in the samples annealed in Ar atmosphere. TEM observation suggested that a small amount of oxygen contained in the Cu films (even a native oxide layer) formed water vapor at elevated temperatures, causing formation of the micro-voids when the samples were annealed in hydrogen atmosphere. The present result suggested that the void formation in the electroplated Cu films was induced by existence of impurities such as oxygen in the Cu films, and that the void growth was strongly enhanced by annealing in hydrogen atmosphere.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"28 1","pages":"1624-1628"},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83270632","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 : 2002-07-01DOI: 10.2320/MATERTRANS.43.1494
K. Sakaki, H. Araki, Y. Shirai
Lattice defects induced by initial hydriding and their effect on residual hydrogen content in LaNi 5 have been studied by means of positron lifetime spectroscopy and hydrogen thermal desorption measurement. Component analyses of positron lifetime spectra show that surprising amount of vacancies together with dislocations are generated by the initial hydriding. Vacancy migration in LaNi 5 after hydrogen desorption at room temperature is observed around 423-673 K, while dislocations in LaNi 5 are much more stable. Hydrogen thermal desorption measurement shows that the release of residual hydrogen occurs mainly in the temperature range from 450 to 650 K, and it ceases at about 800 K. The release temperature of residual hydrogen closely corresponds with the temperature of vacancy migration and annihilation in LaNi 5 . Residual hydrogen in LaNi 5 is most likely trapped by vacancies and vacancy clusters, which are induced by hydriding.
{"title":"Recovery of hydrogen induced defects and thermal desorption of residual hydrogen in LaNi5 : Special issue on grain boundaries, interfaces, defects and localized quantum structures in ceramics","authors":"K. Sakaki, H. Araki, Y. Shirai","doi":"10.2320/MATERTRANS.43.1494","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.1494","url":null,"abstract":"Lattice defects induced by initial hydriding and their effect on residual hydrogen content in LaNi 5 have been studied by means of positron lifetime spectroscopy and hydrogen thermal desorption measurement. Component analyses of positron lifetime spectra show that surprising amount of vacancies together with dislocations are generated by the initial hydriding. Vacancy migration in LaNi 5 after hydrogen desorption at room temperature is observed around 423-673 K, while dislocations in LaNi 5 are much more stable. Hydrogen thermal desorption measurement shows that the release of residual hydrogen occurs mainly in the temperature range from 450 to 650 K, and it ceases at about 800 K. The release temperature of residual hydrogen closely corresponds with the temperature of vacancy migration and annihilation in LaNi 5 . Residual hydrogen in LaNi 5 is most likely trapped by vacancies and vacancy clusters, which are induced by hydriding.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"18 1","pages":"1494-1497"},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86720522","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 : 2002-07-01DOI: 10.2320/MATERTRANS.43.1426
I. Tanaka, F. Oba, K. Tatsumi, M. Kunisu, M. Nakano, H. Adachi
Formation energies of neutral and charged oxygen vacancies in MgO, ZnO, Al 2 O 3 , In 2 O 3 and SnO 2 have been calculated by a first principles plane-wave pseudopotential method. Two kinds of polymorphs, i.e., an ordinary phase and a high-pressure or an hypothetical negative pressure phase, have been chosen in order to see the effects of crystal structure. Supercells composed of 54 to 96 atoms were employed, and structural relaxation around the vacancy within second nearest neighbor distances was taken into account. Defect levels were obtained from the difference in total energies of the neutral and charged supercells that contain a vacancy. Ionization energies of the vacancy were calculated as the difference in the bottom of the conduction band and the defect levels. They are found to be proportional to band-gaps with a factor of approximately 0.5, which are prohibitively large for the n-type conduction.
{"title":"Theoretical formation energy of oxygen-vacancies in oxides : Special issue on grain boundaries, interfaces, defects and localized quantum structures in ceramics","authors":"I. Tanaka, F. Oba, K. Tatsumi, M. Kunisu, M. Nakano, H. Adachi","doi":"10.2320/MATERTRANS.43.1426","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.1426","url":null,"abstract":"Formation energies of neutral and charged oxygen vacancies in MgO, ZnO, Al 2 O 3 , In 2 O 3 and SnO 2 have been calculated by a first principles plane-wave pseudopotential method. Two kinds of polymorphs, i.e., an ordinary phase and a high-pressure or an hypothetical negative pressure phase, have been chosen in order to see the effects of crystal structure. Supercells composed of 54 to 96 atoms were employed, and structural relaxation around the vacancy within second nearest neighbor distances was taken into account. Defect levels were obtained from the difference in total energies of the neutral and charged supercells that contain a vacancy. Ionization energies of the vacancy were calculated as the difference in the bottom of the conduction band and the defect levels. They are found to be proportional to band-gaps with a factor of approximately 0.5, which are prohibitively large for the n-type conduction.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"94 1","pages":"1426-1429"},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83873518","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 : 2002-07-01DOI: 10.2320/MATERTRANS.43.1599
T. Saito, T. Hashimoto, N. Ohashi, T. Fujiwara, H. Yamaguchi
Copper sputtering method for fabrication of high performance logic LSI was studied. Extension of target to substrate distance is effective to improve step coverage of sputtered film combined with reduced operation pressure. Step coverage of low pressure long throw sputtering method also strongly depends upon the feature size of trenches and holes which are formed on silicon wafer. Sub-micron holes and trenches are successfully filled with copper by using this sputtering process followed by re-flow annealing process. Hydrogen annealing process prior to the sputtering deposition on via openings is also investigated to realize good conductivity through the via. This process results in the reduction of copper oxide at the surface of copper film. Using these newly developed processes, 0.2μm node BiCMOS LSI with 4 level copper interconnects was successfully fabricated and high performance of the copper interconnect system was clearly demonstrated.
{"title":"Copper wires for high speed logic LSI prepared by low pressure long throw sputtering method : Special issue on materials-related issues for Cu interconnects used in ultra high speed large scaled integrated Si devices","authors":"T. Saito, T. Hashimoto, N. Ohashi, T. Fujiwara, H. Yamaguchi","doi":"10.2320/MATERTRANS.43.1599","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.1599","url":null,"abstract":"Copper sputtering method for fabrication of high performance logic LSI was studied. Extension of target to substrate distance is effective to improve step coverage of sputtered film combined with reduced operation pressure. Step coverage of low pressure long throw sputtering method also strongly depends upon the feature size of trenches and holes which are formed on silicon wafer. Sub-micron holes and trenches are successfully filled with copper by using this sputtering process followed by re-flow annealing process. Hydrogen annealing process prior to the sputtering deposition on via openings is also investigated to realize good conductivity through the via. This process results in the reduction of copper oxide at the surface of copper film. Using these newly developed processes, 0.2μm node BiCMOS LSI with 4 level copper interconnects was successfully fabricated and high performance of the copper interconnect system was clearly demonstrated.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"40 1","pages":"1599-1604"},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76667192","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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