1) Room temperature electrochemical synthesis allows for uniform coatings of thermoelectric bismuth telluride (Bi2Te3) with tunable composition and stoichiometry in an inexpensive and scalable process.
2) The document details the electrochemical synthesis of Bi2Te3 from bismuth chloride and a tellurium glycolate precursor in an ionic liquid electrolyte.
3) Constant potential electrodeposition at different potentials produced Bi2Te3 coatings with nanoparticle or nanostructured morphologies and varying Bi:Te atomic ratios, demonstrating the ability to control composition through the electrochemical method.
Chapter17 section02 Measuring and Expresing Enthalpy Changes By Hamdy karimHamdy Karim
Students will learn about Heat Enthalpy during the Endothermic and Exothermic Reactions, also they will learn about the Thermochemical Reactions and how they can write their chemical equations!
The large amount of waste heat produced by power plants and automobile engines can be converted into electricity due to the thermoelectric effect, a physics effect that converts temperature differences into electrical energy. As long as you can maintain temperature difference, it will keep on generating electricity, for that one needs a material with low thermal conductivity. in the poster above, a method to reduce thermal conductivity is proposed which in turn increased the efficiency.
The impact of surface hydrogenation on the thermionic electron emission from ...PROMETHEUS Energy
In this work, thermionic electron emission (TEE) from hot
filament chemical vapour deposition polycrystalline diamond
films deposited on p-type silicon substrates was recorded in
the 25–650 8C temperature range. The studied surfaces were
as deposited, as well as hydrogenated by atomic hydrogen
under ultra-high vacuum conditions. The impact of substrate
temperature during hydrogenation, TH, on TEE was studied.
For TH ¼ 25 8C the TEE was found to display a broad maximum
at substrate temperature around 300 8C followed by an
exponential increase. Annealing at 700 8C results in irreversible
changes in surface conditioning, and drastic reduction of TEE
yield at low temperatures. For samples that underwent
hydrogenation at TH ¼ 300 and 500 8C, the TEE yield is
significant at higher temperatures only. The TEE from these
samples is stable also after 700 8C annealing treatment. We
associate these effects with irreversible thermal induced
physicochemical changes of the hydrogen bonding configuration
adsorbed on the polycrystalline diamond surface resulting
in changes in its surface electronic structure which occur upon
annealing to 300 8C.
Chapter17 section02 Measuring and Expresing Enthalpy Changes By Hamdy karimHamdy Karim
Students will learn about Heat Enthalpy during the Endothermic and Exothermic Reactions, also they will learn about the Thermochemical Reactions and how they can write their chemical equations!
The large amount of waste heat produced by power plants and automobile engines can be converted into electricity due to the thermoelectric effect, a physics effect that converts temperature differences into electrical energy. As long as you can maintain temperature difference, it will keep on generating electricity, for that one needs a material with low thermal conductivity. in the poster above, a method to reduce thermal conductivity is proposed which in turn increased the efficiency.
The impact of surface hydrogenation on the thermionic electron emission from ...PROMETHEUS Energy
In this work, thermionic electron emission (TEE) from hot
filament chemical vapour deposition polycrystalline diamond
films deposited on p-type silicon substrates was recorded in
the 25–650 8C temperature range. The studied surfaces were
as deposited, as well as hydrogenated by atomic hydrogen
under ultra-high vacuum conditions. The impact of substrate
temperature during hydrogenation, TH, on TEE was studied.
For TH ¼ 25 8C the TEE was found to display a broad maximum
at substrate temperature around 300 8C followed by an
exponential increase. Annealing at 700 8C results in irreversible
changes in surface conditioning, and drastic reduction of TEE
yield at low temperatures. For samples that underwent
hydrogenation at TH ¼ 300 and 500 8C, the TEE yield is
significant at higher temperatures only. The TEE from these
samples is stable also after 700 8C annealing treatment. We
associate these effects with irreversible thermal induced
physicochemical changes of the hydrogen bonding configuration
adsorbed on the polycrystalline diamond surface resulting
in changes in its surface electronic structure which occur upon
annealing to 300 8C.
SYNTHESIS AND DIELECTRIC CHARACTERIZATION OF BARIUM SUBSTITUTED STRONTIUM BIS...ijrap
The strontium bismuth niobate, SrBi2Nb2O9 (SBN) is a bismuth layered perovskite oxide
compound with potentially useful ferroelectric properties which offer several advantages such as fatigue
free, lead free, low operating voltages, relatively high Curie temperature; and most importantly, their
ferroelectric properties are independent of film thickness. These materials are also important for Fe-RAM
applications having large remanent polarization and low coercivity accompanied by high Curie
temperature for better performance and reliable operation. Present paper describes synthesis, dielectric
properties and impedance studies to reveal the important properties of barium substituted strontium
bismuth niobate, Sr0.85Ba0.15Bi2Nb2O9 in the system Sr1-xBaxBi2Nb2O9(x=0.15).
Synthesis and Dielectric Characterization of Barium Substituted Strontium Bis...ijrap
The strontium bismuth niobate, SrBi2Nb2O9 (SBN) is a bismuth layered perovskite oxide
compound with potentially useful ferroelectric properties which offer several advantages such as fatigue
free, lead free, low operating voltages, relatively high Curie temperature; and most importantly, their
ferroelectric properties are independent of film thickness. These materials are also important for Fe-RAM
applications having large remanent polarization and low coercivity accompanied by high Curie
temperature for better performance and reliable operation. Present paper describes synthesis, dielectric
properties and impedance studies to reveal the important properties of barium substituted strontium
bismuth niobate, Sr0.85Ba0.15Bi2Nb2O9 in the system Sr1-xBaxBi2Nb2O9(x=0.15).
Effect of sintering time on the particle size and dielectric properties of La...ijceronline
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Engineering the Nature of Polarization dynamics in lead-free Relaxors .pptx
BiTe Deposition Poster Final
1. Why electrochemical synthesis?
Room temperature synthesis, friendly reactants, uniform coating, ability to tune –
composition, stoichiometry, producing large areas – inexpensively, easily adapted to
industrial production.
Electrodeposition of Bismuth Telluride (Bi2Te3) from EMIM-BF4
Tiger Yang, Daniel W. Redman, and Keith J. Stevenson
Department of Chemistry and Biochemistry, The University of Texas Austin
Motivation
Nature Materials. 2009, 8, 621 Electrochem. Commun. 2003, 5, 594 Chem. Mater. 2011, 23 (11), 2979
Synthesis of Tellurium Glycolate Precursor
Acknowledgements
Advantages of Ionic Liquids
Large electrochemical window (~3-6 V)
Air and Water Stable
High Thermal Stability
Low Vapor Pressure
Summary
EMIM TFSI
• Seebeck effect: thermoelectric devices convert a difference of
temperature directly into an electric current and create a
temperature difference when given an electric current
• This effect is strongly dependent on the composition of the
material
• Bi2Te3 has shown great promise as a thermoelectric material,
especially when confined to one dimension
• The creation of more efficient, cheaper, and easier methods to
make Bi2Te3 would be greatly beneficial to society
Tellurium dioxide was dissolved in 2 mol eq. of ethylene glycol and a catalytic amount of p-tolenesulfonic
acid was added. The reaction was heated at 120 0C for 4 hours under slightly reduced pressure.
Chlorobenzene was used to azeotropically distill any left over ethylene glycol. The product was washed
with chlorobenzene and the chlorobenzene was removed in vacuo, yielding a crystalline product.
Can. J. Chem. 1983, 61,2199
Electrochemistry and Deposition of Tellurium
5 mM Te(Gly)2 in EMIM-BF4
Working Electrode = Glassy Carbon
Counter Electrode = Pt
Reference Electrode = Pt
Electrochemical Reactions
Te4+ + 4e- → Te0
Te0 + 2e- → Te2-
Te4+ + 6e- → Te2-
Chemical Reactions
2Te2- + Te4+ → 3Te0
SEM of Te
deposit
Electrochemistry and Deposition of Bismuth
5 mM BiCl3 in EMIM-BF4
Working Electrode = Glassy Carbon
Counter Electrode = Pt
Reference Electrode = Pt
Electrochemical Reactions
Bi3+ + 3e- → Bi0
SEM of Bi deposit
Electrochemistry of 2:3 mole ratio BiCl3 + Te(Gly)2
4 mM BiCl3 + 6 mM Te(Gly)2
in EMIM-BF4
Working Electrode = Glassy Carbon
Counter Electrode = Pt
Reference Electrode = Pt
Deposition at E = -0.9 V
~1:1 Bi:Te by EDX
Deposition at E = -1.25 V
~2:1 Bi:Te by EDX
Electrochemistry of 1:1 mole ratio BiCl3 + Te(Gly)2
5 mM BiCl3 + 5 mM Te(Gly)2
in EMIM-BF4
Working Electrode = Glassy Carbon
Counter Electrode = Pt
Reference Electrode = Pt
Deposited at E = -0.85 V
~3:1 Bi:Te by EDX
Deposited at E = -1.1 V
~2:1 Bi:Te by EDX
Rotating Disk Voltammetry of Te(Gly)2 and BiCl3
5 mM BiCl3 in EMIM-BF4
Working Electrode = GC
Counter Electrode = Pt
Reference Electrode = Pt
5 mM Te(Gly)2 in EMIM-BF4
Working Electrode = GC
Counter Electrode = Pt
Reference Electrode = Pt
Rotating Disk Voltammetry of Te- and Bi- Coated
Electrodes
Te-coated GC in BiCl3 in EMIM-BF4
No real difference between Bi
electrochemistry.
Presence of Te reductive stripping
peak
Bi-coated GC in Te(Gly)2 in EMIM-BF4
Only two waves present – no
reductive stripping peak
Possible chemical reaction:
xBi0 + yTe0 → BixTey
Ratio of the diffusion limited current
of wave 1 to wave 2 is ~2/3, which is
consistent with:
Wave 1
Te4+ + 4e- → Te0
Wave 2
Te4+ + 6e- → Te2-
ω = 1000 rpm
ν = 10 mV/s
ω = 1000 rpm
ν = 10 mV/s
ν = 10 mV/s
ν = 10 mV/s
ν = 10 mV/s
ν = 10 mV/s
ω = 1000 rpm
ν = 10 mV/s
ω = 1000 rpm
ν = 10 mV/s
The electrochemical properties of Te(Gly)2 and BiCl3 were investigated using
cyclic voltammetry and hydrodynamic voltammetry. The electrodeposition was
investigated by constant potential deposition. The morphology and elemental
composition was investigated by scanning electron microscopy and energy
dispersive X-ray spectroscopy. Depositions at more negative potentials
resulted in nanoparticle films with ~2:1 atomic ratios of Bi:Te. Depositions at
less negative potentials had more nanostructured (nanowires, nanoflowers,
etc…) with varying atomic ratios depending on the solution composition.