The thermal behaviour (viscosity variation, dilatometric and crystallization trends) of several i... more The thermal behaviour (viscosity variation, dilatometric and crystallization trends) of several iron aluminium magnesium phosphate glasses that contain significant amounts (6–19 wt%) of uranium oxide (UO2·67) is presented as well as new data related to the densification of powder compacts prepared from such compositions. The sintering study of such vitreous powders can help to assess the relative capability for the immobilization and stability of the uranium oxide in these glassy or glass-ceramic matrices.
Chemical reactivity between Ln2NiO4+δ (Ln: La, Nd) electrodes and Y0.08Zr0.92O1.96 (YSZ) and Ce0.... more Chemical reactivity between Ln2NiO4+δ (Ln: La, Nd) electrodes and Y0.08Zr0.92O1.96 (YSZ) and Ce0.9Gd0.1O1.95 (CGO) electrolytes was analyzed by Electrochemical Impedance Spectroscopy (EIS) and Focused Ion Beam-Transmission Electron Microscopy (FIB-TEM) techniques. Ln2NiO4+δ electrodes were deposited onto CGO and YSZ electrolytes by aerography and treated at 900 °C during 1 h in order to promote electrode adhesion. EIS spectra were collected between 500 and 800 °C in dry air. The Polarization Resistances (PR) values for La2NiO4/CGO/La2NiO4 cell are higher than those of La2NiO4/YSZ/La2NiO4. The PR for both cells and its evolution in time suggest that chemical reactivity is developed at 900 °C during the adhesion treatment and at T higher than 650 °C during the EIS measurements. The PR for Nd2NiO4/CGO/Nd2NiO4 and Nd2NiO4/YSZ/Nd2NiO4 are much lower than those of La2NiO4/CGO/La2NiO4 and La2NiO4/YSZ/La2NiO4 cells. These values and the slight increase of PR with time for Nd2NiO4 (NNO) elec...
Focused-ion-beam (FIB) milling has been employed to structure magnetic nanoelements from 20 nm th... more Focused-ion-beam (FIB) milling has been employed to structure magnetic nanoelements from 20 nm thick films of permalloy (Ni 81 Fe 19 ). As permalloy is a soft magnetic material, the magnetic properties are controlled by structural engineering on the nanoscale and novel magnetic phenomena may be exhibited on the nanoscale [1,2]. However, the fabrication of nanostructures in magnetic systems is hampered by the sensitivity of magnetic materials to the resulting structure of the sample edges which plays an important role for the formation of magnetic domains. However, for magnetically soft materials, such as those used in the emerging technology of magneto-electronic devices, the degree to which the magnetic properties of the structured devices suffer due to FIB milling remains unclear. Ion implantation, the introduction of magnetic pinning defects, and nanometer-scale displacements are all ion-induced mechanisms which have recently been shown to strongly influence soft magnetic properties. Therefore, permalloy structures are commonly prepared using electron-beam lithography (EBL), while FIB milling is described in the literature to produce irregular sample edges .
A new technique that allows direct three-dimensional~3D! investigations of mesopores in carbon ma... more A new technique that allows direct three-dimensional~3D! investigations of mesopores in carbon materials and quantitative characterization of their physical properties is reported. Focused ion beam nano-tomography~FIB-nt! is performed by a serial sectioning procedure with a dual beam FIB-scanning electron microscopy instrument. Mesoporous carbons~MPCs! with tailored mesopore size are produced by carbonization of resorcinol-formaldehyde gels in the presence of a cationic surfactant as a pore stabilizer. A visual 3D morphology representation of disordered porous carbon is shown. Pore size distribution of MPCs is determined by the FIB-nt technique and nitrogen sorption isotherm methods to compare both results. The obtained MPCs exhibit pore sizes of 4.7, 7.2, and 18.3 nm, and a specific surface area of ca. 560 m 2 /g.
This work presents microstructural, chemical and mechanical characterization of two alloys (Ru 70... more This work presents microstructural, chemical and mechanical characterization of two alloys (Ru 70 Al 30 and Ru 75 Al 25 (at.%)), which lie close to eutectic point in Ru-Al system. According to the microstructure and chemical analysis, eutectic composition of Ru 76 Al 24 (at.%) has been proposed. RuAl lamellae showed intrinsic deformability when compared with a-Ru lamellae. However, due to high interface density (u=0.6 mm) of fine eutectic structure a joint action of individual phases produces the effect which results in good overall mechanical properties (R 0.2 = 883 MPa, R max = 3178 MPa and A f = 23%). The fracture appearance of both lamellar and rod-like eutectics is fine and fibrous in nature, which is consistent with good ductility and toughness. RuAl dendrites failed in transgranular manner or interface decohesion occurred between RuAl dendrites and Ru halos.
Six new glasses having 45-65wt.% P 2 O 5 , 18-42% Fe 2 O 3 , 6.2-18.7%UO 2.67 and about 6% (Na 2 ... more Six new glasses having 45-65wt.% P 2 O 5 , 18-42% Fe 2 O 3 , 6.2-18.7%UO 2.67 and about 6% (Na 2 O+Al 2 O 3 +MgO) were finally obtained after melting the batches in Al 2 O 3 /MgO crucibles. The higher Tg-T SOFT values were obtained for glasses AR6 (main components: 57.3%P 2 O 5 . 18.4%Fe 2 O 3 . 18.9%UO 2.67 ) and AR7 (mc: 65%P 2 O 5 , 19%Fe 2 O 3 , 9.5%UO 2.67 ) and were the most stable glasses against crystallization. The lowest thermal expansion α was measured for AR1 (mc: 54%P 2 O 5 , 27%Fe 2 O 3 , 13.5%UO 2.67 ). AR7 was the least chemically durable composition, whereas the most durable glasses were those containing the highest percentages of UO 2.67 (AR6, AR1 and AR5). The least stable glasses against crystallization were AR4 (mc: 45.8% ); their DTA crystallization (Tc) peaks were met at 560°C (AR4), 600°C (AR5) and 620°C (AR2). For these glasses Tc increased with UO 2.67 increasing. The highest internal crystallizations were met for AR2 and AR5. Dendritic crystal growth mode was detected for slowly heat treated (up to 650°C) AR5 glass. The dendrite arms were clearly seen by SEM and the EBSD (electron back scattered diffraction) patterns (fitted to phase FePO 4 ) remained unaltered upon moving slightly the detection position throughout those arms.
Analysis of presolar silicate grains provides new knowledge on interstellar and circumstellar env... more Analysis of presolar silicate grains provides new knowledge on interstellar and circumstellar environments and can be used to test models of the Galactic chemical evolution. However, structural information of these grains is rare because sample preparation for transmission electron microscopy is very difficult due to the small dimensions of these grains (<0.5 mum). With the use of the focused ion beam technique thin foils from these grains for transmission electron microscopy analysis can be prepared. Nevertheless, reaching the required precision of some tens of nanometres for the preparation of the transmission electron microscopy foil in the place of interest is not trivial. Furthermore, in the current samples, the grain of interest can only be identified by its different isotopic composition; i.e. there is no contrast difference in scanning electron microscopy or transmission electron microscopy images which allow the identification of the grain. Therefore, the grain has to be marked in some way before preparing the transmission electron microscopy foil. In the present paper, a method for transmission electron microscopy foil preparation of grains about 200 to 400 nm in diameter is presented. The method utilizes marking of the grain by Pt deposition and milling of holes to aid in the exact orientation of the transmission electron microscopy foil with respect to the grain. The proposed method will be explained in detail by using an example grain.
A focused ion beam was employed for local target preparation for EBSD analysis. The volume of the... more A focused ion beam was employed for local target preparation for EBSD analysis. The volume of the ion-solid interaction is well below 50 nm at glancing incidence for metallic and transition metal oxide samples. Therefore, focused ion beam can successfully be used for electron backscatter diffraction (EBSD) sample preparation. The sample investigated consists of Ni covered with a NiO layer of approximately 5 microm thickness. Focused ion beam cross-sectioning of these layers and subsequent electron imaging in addition to EBSD maps shows a bimodal structure of the oxide layer. In order to test the potential of such oxidized samples as electrode materials, single spark erosion experiments were performed. The erosion craters have diameters up to 40 microm and have a depth corresponding to the thickness of the oxide layer. In addition, a deformation zone produced by thermoshock accompanies the formation of the crater. This deformation zone was further investigated by EBSD analysis using a new way of sample preparation employing the focused ion beam technology. This target preparation routine is called Volume of Interest Transfer and has the potential of providing a full three-dimensional characterization.
Study of near surface changes in yttria-doped tetragonal zirconia after low temperature degradati... more Study of near surface changes in yttria-doped tetragonal zirconia after low temperature degradation Full tetragonal 3 mol.% Y 2 O 3 doped zirconia has been subjected to hydrothermal ageing in water at 131 8C in order to study the change in microstructure just below the surface. The degraded layer was examined by scanning and transmission electron microscopy in a section perpendicular to the surface which was prepared by focus ion beam machining. The existence of microcracks and transformed grains in a thin surface layer of the hydrothermal degraded specimens is shown. Scratch damage in annealed and in thermally degraded specimens is compared.
The influence of the microstructure on the oxidation behavior of two-phase near stoichiometric Ru... more The influence of the microstructure on the oxidation behavior of two-phase near stoichiometric RuAl produced by arc melting was investigated. The oxidation was conducted at 1000 8C. The oxide scale growth and phase formation were studied using scanning electron microscopy, focused ion beam microscopy and in situ X-ray diffraction. The microstructure of the samples consisted of RuAl grains with continuous or isolated intergranular phase composed of Ru(Al) or Ru(Al)-RuAl eutectic. The Ru(Al) intergranular layer is prone to oxidation, which was not observed in samples with intergranular Ru(Al)-RuAl eutectic. Porous, poor-protective a-Al 2 O 3 scales were formed. A region with periodic Aluminum oxide/Ruthenium oxide banded layers was developed beneath the external a-Al 2 O 3 scale. Scale growth follows a linear rate law. q
The oxidation behaûior of single-phase RuAl produced by powder metallurgy combined with arc melti... more The oxidation behaûior of single-phase RuAl produced by powder metallurgy combined with arc melting was inûestigated. Oxidation was conducted at 1000°C; oxide scale growth and phase formation were studied using scanningelectron microscopy (SEM) and x-ray diffraction (XRD). A dense protectiûe scale with an Al-depleted sublayer was formed during oxidation. The oxide scale is the stable α-Al 2 O 3 . The oxide-scale morphology shows the presence of whiskers, with a needle-like form, which suggests that the growth of the oxide scale is produced by outward diffusion of Al. At the beginning, oxidation follows a parabolic law, but, after 100 hr of oxidation; the growth rate is slower than expected from a parabolic law.
... By Jochen Rager,* Alexander Flaig, Gerhard Schneider, Thomas Kaiser, Flavio Soldera, and Fran... more ... By Jochen Rager,* Alexander Flaig, Gerhard Schneider, Thomas Kaiser, Flavio Soldera, and Frank M¸cklich ... The discharge can be divided into three phases:[1] The breakdown phase, in which the conductive plasma channel is established, followed by the arc and the glow ...
... using FIB/SEM Dual Beam Techniques** By Nicolas Jeanvoine,* Christian Holzapfel, Flavio Solde... more ... using FIB/SEM Dual Beam Techniques** By Nicolas Jeanvoine,* Christian Holzapfel, Flavio Soldera, and Frank Mücklich ... The ignition discharge occurring in spark plugs can be divided into three different phases: the breakdown, the arc discharge and the glow discharge. ...
The thermal behaviour (viscosity variation, dilatometric and crystallization trends) of several i... more The thermal behaviour (viscosity variation, dilatometric and crystallization trends) of several iron aluminium magnesium phosphate glasses that contain significant amounts (6–19 wt%) of uranium oxide (UO2·67) is presented as well as new data related to the densification of powder compacts prepared from such compositions. The sintering study of such vitreous powders can help to assess the relative capability for the immobilization and stability of the uranium oxide in these glassy or glass-ceramic matrices.
Chemical reactivity between Ln2NiO4+δ (Ln: La, Nd) electrodes and Y0.08Zr0.92O1.96 (YSZ) and Ce0.... more Chemical reactivity between Ln2NiO4+δ (Ln: La, Nd) electrodes and Y0.08Zr0.92O1.96 (YSZ) and Ce0.9Gd0.1O1.95 (CGO) electrolytes was analyzed by Electrochemical Impedance Spectroscopy (EIS) and Focused Ion Beam-Transmission Electron Microscopy (FIB-TEM) techniques. Ln2NiO4+δ electrodes were deposited onto CGO and YSZ electrolytes by aerography and treated at 900 °C during 1 h in order to promote electrode adhesion. EIS spectra were collected between 500 and 800 °C in dry air. The Polarization Resistances (PR) values for La2NiO4/CGO/La2NiO4 cell are higher than those of La2NiO4/YSZ/La2NiO4. The PR for both cells and its evolution in time suggest that chemical reactivity is developed at 900 °C during the adhesion treatment and at T higher than 650 °C during the EIS measurements. The PR for Nd2NiO4/CGO/Nd2NiO4 and Nd2NiO4/YSZ/Nd2NiO4 are much lower than those of La2NiO4/CGO/La2NiO4 and La2NiO4/YSZ/La2NiO4 cells. These values and the slight increase of PR with time for Nd2NiO4 (NNO) elec...
Focused-ion-beam (FIB) milling has been employed to structure magnetic nanoelements from 20 nm th... more Focused-ion-beam (FIB) milling has been employed to structure magnetic nanoelements from 20 nm thick films of permalloy (Ni 81 Fe 19 ). As permalloy is a soft magnetic material, the magnetic properties are controlled by structural engineering on the nanoscale and novel magnetic phenomena may be exhibited on the nanoscale [1,2]. However, the fabrication of nanostructures in magnetic systems is hampered by the sensitivity of magnetic materials to the resulting structure of the sample edges which plays an important role for the formation of magnetic domains. However, for magnetically soft materials, such as those used in the emerging technology of magneto-electronic devices, the degree to which the magnetic properties of the structured devices suffer due to FIB milling remains unclear. Ion implantation, the introduction of magnetic pinning defects, and nanometer-scale displacements are all ion-induced mechanisms which have recently been shown to strongly influence soft magnetic properties. Therefore, permalloy structures are commonly prepared using electron-beam lithography (EBL), while FIB milling is described in the literature to produce irregular sample edges .
A new technique that allows direct three-dimensional~3D! investigations of mesopores in carbon ma... more A new technique that allows direct three-dimensional~3D! investigations of mesopores in carbon materials and quantitative characterization of their physical properties is reported. Focused ion beam nano-tomography~FIB-nt! is performed by a serial sectioning procedure with a dual beam FIB-scanning electron microscopy instrument. Mesoporous carbons~MPCs! with tailored mesopore size are produced by carbonization of resorcinol-formaldehyde gels in the presence of a cationic surfactant as a pore stabilizer. A visual 3D morphology representation of disordered porous carbon is shown. Pore size distribution of MPCs is determined by the FIB-nt technique and nitrogen sorption isotherm methods to compare both results. The obtained MPCs exhibit pore sizes of 4.7, 7.2, and 18.3 nm, and a specific surface area of ca. 560 m 2 /g.
This work presents microstructural, chemical and mechanical characterization of two alloys (Ru 70... more This work presents microstructural, chemical and mechanical characterization of two alloys (Ru 70 Al 30 and Ru 75 Al 25 (at.%)), which lie close to eutectic point in Ru-Al system. According to the microstructure and chemical analysis, eutectic composition of Ru 76 Al 24 (at.%) has been proposed. RuAl lamellae showed intrinsic deformability when compared with a-Ru lamellae. However, due to high interface density (u=0.6 mm) of fine eutectic structure a joint action of individual phases produces the effect which results in good overall mechanical properties (R 0.2 = 883 MPa, R max = 3178 MPa and A f = 23%). The fracture appearance of both lamellar and rod-like eutectics is fine and fibrous in nature, which is consistent with good ductility and toughness. RuAl dendrites failed in transgranular manner or interface decohesion occurred between RuAl dendrites and Ru halos.
Six new glasses having 45-65wt.% P 2 O 5 , 18-42% Fe 2 O 3 , 6.2-18.7%UO 2.67 and about 6% (Na 2 ... more Six new glasses having 45-65wt.% P 2 O 5 , 18-42% Fe 2 O 3 , 6.2-18.7%UO 2.67 and about 6% (Na 2 O+Al 2 O 3 +MgO) were finally obtained after melting the batches in Al 2 O 3 /MgO crucibles. The higher Tg-T SOFT values were obtained for glasses AR6 (main components: 57.3%P 2 O 5 . 18.4%Fe 2 O 3 . 18.9%UO 2.67 ) and AR7 (mc: 65%P 2 O 5 , 19%Fe 2 O 3 , 9.5%UO 2.67 ) and were the most stable glasses against crystallization. The lowest thermal expansion α was measured for AR1 (mc: 54%P 2 O 5 , 27%Fe 2 O 3 , 13.5%UO 2.67 ). AR7 was the least chemically durable composition, whereas the most durable glasses were those containing the highest percentages of UO 2.67 (AR6, AR1 and AR5). The least stable glasses against crystallization were AR4 (mc: 45.8% ); their DTA crystallization (Tc) peaks were met at 560°C (AR4), 600°C (AR5) and 620°C (AR2). For these glasses Tc increased with UO 2.67 increasing. The highest internal crystallizations were met for AR2 and AR5. Dendritic crystal growth mode was detected for slowly heat treated (up to 650°C) AR5 glass. The dendrite arms were clearly seen by SEM and the EBSD (electron back scattered diffraction) patterns (fitted to phase FePO 4 ) remained unaltered upon moving slightly the detection position throughout those arms.
Analysis of presolar silicate grains provides new knowledge on interstellar and circumstellar env... more Analysis of presolar silicate grains provides new knowledge on interstellar and circumstellar environments and can be used to test models of the Galactic chemical evolution. However, structural information of these grains is rare because sample preparation for transmission electron microscopy is very difficult due to the small dimensions of these grains (<0.5 mum). With the use of the focused ion beam technique thin foils from these grains for transmission electron microscopy analysis can be prepared. Nevertheless, reaching the required precision of some tens of nanometres for the preparation of the transmission electron microscopy foil in the place of interest is not trivial. Furthermore, in the current samples, the grain of interest can only be identified by its different isotopic composition; i.e. there is no contrast difference in scanning electron microscopy or transmission electron microscopy images which allow the identification of the grain. Therefore, the grain has to be marked in some way before preparing the transmission electron microscopy foil. In the present paper, a method for transmission electron microscopy foil preparation of grains about 200 to 400 nm in diameter is presented. The method utilizes marking of the grain by Pt deposition and milling of holes to aid in the exact orientation of the transmission electron microscopy foil with respect to the grain. The proposed method will be explained in detail by using an example grain.
A focused ion beam was employed for local target preparation for EBSD analysis. The volume of the... more A focused ion beam was employed for local target preparation for EBSD analysis. The volume of the ion-solid interaction is well below 50 nm at glancing incidence for metallic and transition metal oxide samples. Therefore, focused ion beam can successfully be used for electron backscatter diffraction (EBSD) sample preparation. The sample investigated consists of Ni covered with a NiO layer of approximately 5 microm thickness. Focused ion beam cross-sectioning of these layers and subsequent electron imaging in addition to EBSD maps shows a bimodal structure of the oxide layer. In order to test the potential of such oxidized samples as electrode materials, single spark erosion experiments were performed. The erosion craters have diameters up to 40 microm and have a depth corresponding to the thickness of the oxide layer. In addition, a deformation zone produced by thermoshock accompanies the formation of the crater. This deformation zone was further investigated by EBSD analysis using a new way of sample preparation employing the focused ion beam technology. This target preparation routine is called Volume of Interest Transfer and has the potential of providing a full three-dimensional characterization.
Study of near surface changes in yttria-doped tetragonal zirconia after low temperature degradati... more Study of near surface changes in yttria-doped tetragonal zirconia after low temperature degradation Full tetragonal 3 mol.% Y 2 O 3 doped zirconia has been subjected to hydrothermal ageing in water at 131 8C in order to study the change in microstructure just below the surface. The degraded layer was examined by scanning and transmission electron microscopy in a section perpendicular to the surface which was prepared by focus ion beam machining. The existence of microcracks and transformed grains in a thin surface layer of the hydrothermal degraded specimens is shown. Scratch damage in annealed and in thermally degraded specimens is compared.
The influence of the microstructure on the oxidation behavior of two-phase near stoichiometric Ru... more The influence of the microstructure on the oxidation behavior of two-phase near stoichiometric RuAl produced by arc melting was investigated. The oxidation was conducted at 1000 8C. The oxide scale growth and phase formation were studied using scanning electron microscopy, focused ion beam microscopy and in situ X-ray diffraction. The microstructure of the samples consisted of RuAl grains with continuous or isolated intergranular phase composed of Ru(Al) or Ru(Al)-RuAl eutectic. The Ru(Al) intergranular layer is prone to oxidation, which was not observed in samples with intergranular Ru(Al)-RuAl eutectic. Porous, poor-protective a-Al 2 O 3 scales were formed. A region with periodic Aluminum oxide/Ruthenium oxide banded layers was developed beneath the external a-Al 2 O 3 scale. Scale growth follows a linear rate law. q
The oxidation behaûior of single-phase RuAl produced by powder metallurgy combined with arc melti... more The oxidation behaûior of single-phase RuAl produced by powder metallurgy combined with arc melting was inûestigated. Oxidation was conducted at 1000°C; oxide scale growth and phase formation were studied using scanningelectron microscopy (SEM) and x-ray diffraction (XRD). A dense protectiûe scale with an Al-depleted sublayer was formed during oxidation. The oxide scale is the stable α-Al 2 O 3 . The oxide-scale morphology shows the presence of whiskers, with a needle-like form, which suggests that the growth of the oxide scale is produced by outward diffusion of Al. At the beginning, oxidation follows a parabolic law, but, after 100 hr of oxidation; the growth rate is slower than expected from a parabolic law.
... By Jochen Rager,* Alexander Flaig, Gerhard Schneider, Thomas Kaiser, Flavio Soldera, and Fran... more ... By Jochen Rager,* Alexander Flaig, Gerhard Schneider, Thomas Kaiser, Flavio Soldera, and Frank M¸cklich ... The discharge can be divided into three phases:[1] The breakdown phase, in which the conductive plasma channel is established, followed by the arc and the glow ...
... using FIB/SEM Dual Beam Techniques** By Nicolas Jeanvoine,* Christian Holzapfel, Flavio Solde... more ... using FIB/SEM Dual Beam Techniques** By Nicolas Jeanvoine,* Christian Holzapfel, Flavio Soldera, and Frank Mücklich ... The ignition discharge occurring in spark plugs can be divided into three different phases: the breakdown, the arc discharge and the glow discharge. ...
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