- FeSiGe exhibits insignificant oxide growth and microstructural changes at temperatures up to 900°C, as shown by oxidation studies using SEM, EDS, and weight measurements.
- Germanium in FeSiGe is preferentially oxidized, forming a thin SiO2 oxide layer, as demonstrated by EDS mapping.
- Oxidation is minimal for ribbon FeSiGe at 600°C but increases slightly for bulk FeSiGe at the same temperature, indicating Germanium oxidation. Significant oxidation occurs for bulk FeSiGe at 900°C.
- The findings suggest FeSiGe is suitable for high-temperature thermoelectric applications due to its oxidation resistance at operating temperatures.
Stability of expanded austenite, generated by ion carburizing and ion nitridi...Javier García Molleja
Authors: J. García Molleja, M. Milanese, M. Piccoli, R. Moroso, J. Niedbalski, L. Nosei, J. Bürgi, E. Bemporad, J. Feugeas
Surface and Coatings Technology 218 (2013) 142-151 (March 15th 2013)
Only the first page is uploaded because Elsevier's copyrigth policy. Available at: http://dx.doi.org/10.1016/j.surfcoat.2012.12.043
Surfactant Assisted Growth and Optical Studies of NiCo2O4 Nanostructures thro...Editor IJCATR
A fast and facile method has been imposed for the preparation of NiCo2O4 nanostructures using metal nitrate as a precursor
material and CTAB as a surfactant. The prepared samples were characterized by Powder X-ray diffraction (XRD), Fourier transform
infrared (FT-IR), Scanning electron microscopy (SEM), Raman and PL spectroscopy. It was found that the synthesis route proposed in this
work favored the formation of NiCo2O4 spinel phase at low temperature. The surfactant CTAB was chosen to control over the nucleation,
growth and agglomeration nature of observed NiCo2O4 nanocrystalline products. With the effect of surfactant, the obtained NiCo2O4 has
been used for various promising potential applications. Based on the observed experimental observations and analysis, a possible
microwave reaction mechanism is proposed to synthesis NiCo2O4 nanostructured materials to enrich the structural, morphological and
optical properties of NiCo2O4 nanostructures
Dendritic Electroless Deposits of Lead From Lead Acetate Solutioninventionjournals
Electroless deposition of lead from lead acetate is studied in a planar cell geometry. Dendritic patterns are grown using electroless deposition in planar cell geometry. Electroless deposition cell is designed and constructed and the depositions obtained are analysed for self similarity and fractal characterization. Details and findings are presented
Stability of expanded austenite, generated by ion carburizing and ion nitridi...Javier García Molleja
Authors: J. García Molleja, M. Milanese, M. Piccoli, R. Moroso, J. Niedbalski, L. Nosei, J. Bürgi, E. Bemporad, J. Feugeas
Surface and Coatings Technology 218 (2013) 142-151 (March 15th 2013)
Only the first page is uploaded because Elsevier's copyrigth policy. Available at: http://dx.doi.org/10.1016/j.surfcoat.2012.12.043
Surfactant Assisted Growth and Optical Studies of NiCo2O4 Nanostructures thro...Editor IJCATR
A fast and facile method has been imposed for the preparation of NiCo2O4 nanostructures using metal nitrate as a precursor
material and CTAB as a surfactant. The prepared samples were characterized by Powder X-ray diffraction (XRD), Fourier transform
infrared (FT-IR), Scanning electron microscopy (SEM), Raman and PL spectroscopy. It was found that the synthesis route proposed in this
work favored the formation of NiCo2O4 spinel phase at low temperature. The surfactant CTAB was chosen to control over the nucleation,
growth and agglomeration nature of observed NiCo2O4 nanocrystalline products. With the effect of surfactant, the obtained NiCo2O4 has
been used for various promising potential applications. Based on the observed experimental observations and analysis, a possible
microwave reaction mechanism is proposed to synthesis NiCo2O4 nanostructured materials to enrich the structural, morphological and
optical properties of NiCo2O4 nanostructures
Dendritic Electroless Deposits of Lead From Lead Acetate Solutioninventionjournals
Electroless deposition of lead from lead acetate is studied in a planar cell geometry. Dendritic patterns are grown using electroless deposition in planar cell geometry. Electroless deposition cell is designed and constructed and the depositions obtained are analysed for self similarity and fractal characterization. Details and findings are presented
Study of Crystallization Process of Fe78Tm2B20 and Fe76Tm4B20 AlloysIJERA Editor
The amorphous to crystalline transformation in Fe78Tm2B20 (Sample S1) and Fe76Tm4B20 (Sample S2) alloys has been carried out using Differential Scanning Calorimetry (DSC). Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) of the samples are also discussed to confirm the complete crystallization after heating. DSC analysis of the samples S1 and S2 showed that on heating the samples upto 10000C, a sharp peak was observed at 5450C and 7910C respectively, indicating a primary crystalline phase appearing in the amorphous matrix. In sample S2 another sharp peak was observed at 8960C, indicating further crystallization in the sample. Both the samples are completely crystallized when temperature is above 9290C. In sample S2, the crystallization is a multi stage process where different crystalline phases grow in the amorphous matrix. SEM patterns of these samples showed that as cast samples are amorphous and the sample are completely crystallized when heated to 10000C. EDS patterns also confirmed the complete crystallization of the samples after heating to 10000C. Thus increase of Tm concentration in Fe-Tm-B alloy changes the process of crystallization.
Para llogar una casa en España es muy difícil durante las vacaciones. Catalunya Casas es una agencia de lloguer de vacacional con sede en Barcelona que ofrece casas rural en forma temporal en Barcelona y Costa Brava.
This webinar covers the fundamentals of Value Pricing so that participants can:
Understand the relationship of pricing with the other elements of the marketing mix.
Achieve the value you deserve through optimal pricing strategies that maximize profits.
Ensure that marketing is more proactive to optimize value for new products and maintaining value over different life cycles.
Study of Crystallization Process of Fe78Tm2B20 and Fe76Tm4B20 AlloysIJERA Editor
The amorphous to crystalline transformation in Fe78Tm2B20 (Sample S1) and Fe76Tm4B20 (Sample S2) alloys has been carried out using Differential Scanning Calorimetry (DSC). Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) of the samples are also discussed to confirm the complete crystallization after heating. DSC analysis of the samples S1 and S2 showed that on heating the samples upto 10000C, a sharp peak was observed at 5450C and 7910C respectively, indicating a primary crystalline phase appearing in the amorphous matrix. In sample S2 another sharp peak was observed at 8960C, indicating further crystallization in the sample. Both the samples are completely crystallized when temperature is above 9290C. In sample S2, the crystallization is a multi stage process where different crystalline phases grow in the amorphous matrix. SEM patterns of these samples showed that as cast samples are amorphous and the sample are completely crystallized when heated to 10000C. EDS patterns also confirmed the complete crystallization of the samples after heating to 10000C. Thus increase of Tm concentration in Fe-Tm-B alloy changes the process of crystallization.
Para llogar una casa en España es muy difícil durante las vacaciones. Catalunya Casas es una agencia de lloguer de vacacional con sede en Barcelona que ofrece casas rural en forma temporal en Barcelona y Costa Brava.
This webinar covers the fundamentals of Value Pricing so that participants can:
Understand the relationship of pricing with the other elements of the marketing mix.
Achieve the value you deserve through optimal pricing strategies that maximize profits.
Ensure that marketing is more proactive to optimize value for new products and maintaining value over different life cycles.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Studies on Electrical and Sensing Properties of Polyaniline / Iron Oxide (-F...IJERA Editor
Polyaniline iron oxide nanocomposites were prepared by in-situ polymerization method. These
nanocomposites were characterized by employing Fourier Transform Infrared (FT-IR), Scanning Electron
Microscope (SEM),Thermal study by (TGA).The dc conductivity of prepared nanocomposites was measured as
a function of temperature which shows the strong interaction between Polyaniline and iron oxide nanoparticles
and exhibits semiconducting behavior.Finally, the sensing properties of these nanocomposites are also studied at
room temperature.
Electro-Thermal and Semiconductivity Behaviour of Natural Sintered Complex Ca...Al Baha University
The electrical
conductivity (휎), thermal conductivity (퐾) and thermoelectric power coefficient (훼) have been investigated as a function of applied
temperature for the sintered ore materials. The electrical conduction is mainly achieved by free electrons near or in conduction
band or n-type. As the sintering temperature (푇s) increases the conduction of the ore is also increased due to the recombination
process taking place between the electrons and holes. Electrons hopping between Fe2+ and Fe3+ are the main charge carriers.The
formation of Fe3O4 at high sintering temperature acts as an active mineralizer, thus inducing an increased degree of crystallinity
and a more ordered crystal structure is produced.
Study the effect of Mn2+ ions on the ac electrical properties of some iron do...IJRES Journal
Oxide glasses doped with transition metal ions are of high interest because of their variant applications in both science and technology fields. However, the normal melt quench method have used to prepared some iron doped phosphate glasses according the following molecular formula: (65-x) mol% P2O5 - 20 mol% Na2O - 15 mol% Fe2O3 - x mol% MnO, Where x= 0, 5,10, 20, 25. The room temperature Mössbauer Effect ME Spectra used to characterized the glassy state homogeneity of these glasses. ME spectra show, for all glasses, no magnetic field participate which mean good glassy state formation. The ac electrical transport properties were also measured, as function of temperature up to 500k. It was found that the ac conductivity increased with the gradual increase of Mn2+ cations, while the electrical activation energy decreased.
1. High Temperature Oxidation Studies of FeSiGe
Jonathan E. Valenzuela, Wade A. Jensen, Jerrold A. Floro, Elizabeth J. Opila
Department of Materials Science and Engineering
University of Virginia, Charlottesville, VA 22904
Objective
Characterize the oxidation behavior of FeSiGe at high temperatures.
Results: Oxidation Time Dependence
Oxidation studies were carried out in a box furnace for 48-120 hours at 600°C
(temperature at which thermoelectric phase β-FeSi2 has maximum thermoelectric
efficiency) for bulk and ribbon FeSiGe and 900°C (maximum temperature before β-
FeSi2 transforms to α-FeSi2), for bulk FeSiGe. No significant weight change detected. Results: Oxidation Temperature Dependence
5 oxidation tests were carried out by box furnace from 500- 900°C for 24 hours each
with the ribbon material. SEM, EDS, and weight change was monitored.
Summary
FeSiGe is a good candidate for high temperature thermoelectric use!
• Insignificant oxide growth and microstructural coarsening effects at
optimum and maximum thermoelectric use temperatures, as
demonstrated by EDS.
• We hypothesize that a SiO2 is the oxide being grown, as
demonstrated by EDS and interference colors produced from the
oxide.
• Ge in FeSiGe is preferentially oxidized, as demonstrated by EDS
mapping.
References: (1.) Snyder, G. Jeffrey, and Eric S. Toberer. “Complex Thermoelectric Materials.” (2.) Ware, R.M.; McNeill, D.J., "Iron disilicide as a
thermoelectric generator material" (3.) Birks, Neil, Gerald H. Meier, and Frederick S. Pettit. Introduction to the High Temperature Oxidation of
Metals.(4.) Deal, B. E.; A. S. Grove (December 1965). "General Relationship for the Thermal Oxidation of Silicon". (5.) Gesmundo, F., and B.
Gleeson. “Oxidation of Multicomponent Two-Phase Alloys.” (6.) Pujilaksono, Bagas et al. “Oxidation of Iron at 400–600 °C in Dry and Wet O2.”
(7.) Nanko, Makoto et al. “Isothermal Oxidation of Sintered Β-FeSi2 in Air.” (8.) F.K. LeGoues, R. Rosenburg, T. Nguyen, F. Himpsel, and
B.S.Meyerson. “Oxidation Studies of SiGe”. (9.) J. Henrie, S. Kellis, S. Schultz, A. Hawkins. “Electric color charts for dielectric films on silicon”.
Future Work
Further testing needed to confirm
oxidation behavior.
• X-ray photoelectron spectroscopy on
nanoscale oxide layer to confirm
oxide composition
• Additional sample cross-section SEM
characterization
• Thermoelectric property
measurements after oxidation
Acknowledgements
Many thanks to Jerry Floro and
Wade Jensen for providing the
material for testing and the National
Science Foundation (NSF Grant
#1157007) for the funding for this
research.
Experimental: Processing
and Oxidation Tests
Preparation of Material
• Bulk: Arc melting, produces coarse
microstructure (Fig. 4)
• Ribbon : Arc melting and melt spinning for
rapid solidification, produces fine
microstructure (Fig. 5)
• All samples were encapsulated in Ar gas
and annealed at 567°C for 56 hours to
produce the thermoelectric β-FeSi2 phase7
Oxidation Time Dependence
• Oxidized for 48, 72, 96, and 120 hours at
600°C and 900°C in a box furnace (Fig. 6) in
ambient air
• 600°C for bulk and ribbon FeSiGe & 900°C
for bulk FeSiGe
Oxidation Temperature Dependence
• 5 samples of ribbon FeSiGe oxidized at
500, 600, 700, 800, 900°C for 24 hours in a
box furnace (Fig. 6) in ambient air
• 31 day oxidation for ribbon and bulk
FeSiGe at 700°C
Introduction
What is a thermoelectric material?
Material that converts a thermal gradient to electrical energy1, 2.
Material System
FeSiGe is a multiphase material composed of β-FeSi2 and SiGe formed by a
eutectoid decomposition of α-FeSi2 as shown in the binary phase diagram (Fig. 1). This
alloy is attractive for thermoelectric use because the raw materials used to create this
material are earth abundant, non-toxic and, presumably, oxidation resistant for waste
heat recovery.
Why are we doing this?
It is not known how this material will oxidize at higher temperatures. This is
especially important to know on the hot side of the thermoelectric device, in which
oxidation is most likely to happen. High temperature multiphase oxidation can
complicate the oxidation behavior of a material3. Three forms of oxide products4 (Fig. 2)
can form during the oxidation of multiphase materials like FeSiGe.
1. The two phases can oxidize independently to form non-uniform scale.
2. Two phases oxidize cooperatively to form uniform scale.
3. Solute rich second phase acts as reservoir for continued growth of solute scale.
(Oxidation of one phase dominates)
The particular oxidation product formed on a multiphase material is dominated
by the thermodynamics and kinetics of the possible oxidation reactions. Possible
oxidation reactions are listed in Fig. 35,6. Thermodynamic predictions on the oxide to be
formed indicate that SiO2 will be the oxide formed in these conditions.
High temperature thermal gradients could have various effects on the material.
Oxidation could consume the thermoelectric substrate at a higher rate, or the higher
temperature could transform the microstructure via coarsening, reducing the
effectiveness of the thermoelectric device. Therefore, it is important to learn the
behavior of this material to confirm that it is appropriate for high temperature use.
Fig. 8 Oxygen EDS maps to indicate oxidation on material. For oxidation at 600°C, little to no
oxidation was observed until 96 hours, where definitive oxygen gain on the surface of FeSiGe is seen.
Fig. 9 SEM images and oxygen EDS maps shown for oxidation exposures at 600°C. Some oxidations
occurs, increasing with time.
Fig. 10 SEM images and oxygen EDS maps of bulk FeSiGe after 900°C oxidation exposures. Oxygen
increases significantly compared to 600°C exposures. SiO2 growth hypothesized.
Fig. 12 Images of FeSiGe melt spun specimen before and after
oxidation at 900 C for 24 hours in air. Note the interference color on
the post-exposure due to formation of a thin oxide layer9.
Experimental: Characterization
Characterization
• Gravimetry: weight change measured for
oxidation kinetics
• Scanning Electron Microscopy (SEM): topography
and compositional data, secondary and
backscattered electrons measured
• Energy Dispersive Spectroscopy (EDS): elemental
and compositional data, x-rays analyzed Fig. 7 Electron interaction
volume. Electron/waves at
specific energies give different
info. on material.
oxidation oxide interference colors
600°C Ribbon: Insignificant oxidation
600°C Bulk: Minimal oxidation
900°C Bulk: Significant Oxidation
Preferential Oxidation of Germanium
Results: Oxidation Time Dependence (cont’d)
Ox. Time
(hours) Fe (at%) Si (at%)
Ge
(at%) O (at%)
72 22.9 54.5 8.8 13.8
Ox. Time
(hours) Fe (at%) Si (at%)
Ge
(at%) O (at%)
120 20.2 53.2 8.4 18.2
Ox. Time
(hours) Fe (at%) Si (at%)
Ge
(at%) O (at%)
96 21.6 54.2 7.4 16.8
Ox. Time
(hours) Fe (at%) Si (at%)
Ge
(at%) O (at%)
48 21.2 51.2 7.4 20.2
Ox. Time
(hours) Fe (at%) Si (at%)
Ge
(at%) O (at%)
96 22.3 47.7 7.5 22.5
Ox. Time
(hours) Fe (at%) Si (at%)
Ge
(at%) O (at%)
120 21.3 43.5 7.9 27.3
Ox. Time
(hours) Fe (at%) Si (at%)
Ge
(at%) O (at%)
48 16.1 40.6 6.2 37.1
Ox. Time
(hours) Fe (at%) Si (at%)
Ge
(at%) O (at%)
72 12.6 40.4 5.6 41.4
Ox. Time
(hours) Fe (at%) Si (at%) Ge (at%)O (at%)
120 12.7 39.3 4.8 43.2
Fig. 11 Electron image and EDS maps of ribbon FeSiGe after 600°C for 96 hours. Definitive oxygen gain
detected on the surface of FeSiGe favoring Ge-rich sites consistent with prior literature for SiGe8.
Hypothesized SiO2 Formation
β-
FeSi2 SiGe
Fig. 4 Pre Ox.
Bulk FeSiGe
SEM Image
SiGe
β-
FeSi2
Fig. 6 Model of furnace set up
Insulating material
Alumina boat
Fused silica slide
Fig. 5 Pre Ox.
Ribbon FeSiGe
SEM Image
Fig. 1 Phase diagram of Fe-Si. α-FeSi2
transforms to β-FeSi2 at 937ºC.
Oxygen Germanium
Silicon
Fe Si Ge
𝑭𝒆 𝒔 +
𝟏
𝟐
𝑶 𝟐(𝒈)
→ 𝑭𝒆𝑶(𝒔)
𝑺𝒊 𝒔 + 𝑶 𝟐(𝒈)
→ 𝑺𝒊𝑶 𝟐(𝒔)
𝐆𝒆 𝒔 + 𝑶 𝟐
→ 𝑮𝒆𝑶 𝟐
𝟒𝑭𝒆 𝒔 + 𝟑𝑶 𝟐(𝒈)
→ 𝟐𝑭𝒆 𝟐 𝑶 𝟑
𝟑𝑭𝒆 𝒔 + 𝟐𝑶 𝟐(𝒈)
→ 𝑭𝒆 𝟑 𝑶 𝟒(𝒔)
Iron
Minimal Microstructural Coarsening Effects
Fig. 13 Spacing between FeSi2 remains consistently around 7-10 microns, and 2-3 microns, for bulk and
ribbon respectively.
7 microns
7 microns
10 microns
8 microns
2 microns 2 microns 3 microns 2 micronsFig. 2 Multiphase oxidation modes.
Fig. 3 Possible oxidation reactions in FeSiGe.
Bulk
Ribbon
600 C, 72 hours 650 C, 72 hours 700 C, 72 hours 700 C, 31 days
20 μm
4 µm
Editor's Notes
10 min presentation, 5 min of questions
1. Statement of research problem/rationale:
2. Literature review:
3. Theoretical framework
4. Analysis of results
5. Conclusions/Discussions
6. Poster
7. Oral Presentation:
Opila mark up:
Differentiate the oxidation from thermoelectric material more clearly.
Describe advantages of FeSiGe as a thermoelectric material
earth abundant
presumably oxidation resistant for waste heat recovery
Figure numbers in text
Write some oxidation reactions. Which will happen? Fe oxide, Si oxide, Ge oxide?
Describe the length scales of the microstructures for arc melted and melt ribbons- relate to the figure on different oxide phases possible
Explain oxidation procedure - box furnace in stagnant ambient air, boats, inserting, removing
Does your audience know what SEM/EDS are? Explain more? Show interaction volume. Were all your EDS results obtained at the same accelerating voltage?
Do you have numbers for the measured oxygen content?
Discuss the preferential oxidation of Germanium before the conclusions. Cite literature.
Include your 31 day oxidation results?
Discuss any effects of microstructure length scale on oxidation bringing your discussion round to the figure in the introduction.
Your results address only one aspect of using FeSiGe for TE. Future work also involves TE characterization of material.
more comments on poster .pdf.
Note the margins
FeSiGe crappy thermoelectric
Intro: introduce material system, what am I doing to the material, why am I doing this
Change font to 24 pt?
Add oxidation reactions !!!