| 1. |
- Rehnlund, David, 1986-, et al.
(författare)
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Lithium trapping in alloy forming electrodes and current collectors for lithium based batteries
- 2017
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Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 10:6, s. 1350-1357
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Tidskriftsartikel (refereegranskat)abstract
- Significant capacity losses are generally seen for batteries containing high-capacity lithium alloy forming anode materials such as silicon, tin and aluminium. These losses are generally ascribed to a combination of volume expansion effects and irreversible electrolyte reduction reactions. Here, it is shown, based on e.g. elemental analyses of cycled electrodes, that the capacity losses for tin nanorod and silicon composite electrodes in fact involve diffusion controlled trapping of lithium in the electrodes. While an analogous effect is also demonstrated for copper, nickel and titanium current collectors, boron-doped diamond is shown to function as an effective lithium diffusion barrier. The present findings indicate that the durability of lithium based batteries can be improved significantly via proper electrode design or regeneration of the used electrodes. © The Royal Society of Chemistry 2017.
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| 2. |
- Zou, Yiming, 1985-, et al.
(författare)
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Effect of Boron Doping on the CVD Growth Rate of Diamond
- 2016
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 120:19, s. 10658-10666
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Tidskriftsartikel (refereegranskat)abstract
- The purpose with the present study has been to theoretically investigate the effect of boron doping on the diamond growth rate. The most frequently observed diamond surface planes (100), (111) and (110) were thereby carefully investigated using density functional theory calculations under periodic boundary conditions. It was shown that both the thermodynamic and kinetic aspects of the diamond growth process will be severely affected by the B dopant (as compared with the non-doped situations). More specifically, the results showed that B (positioned within the 2nd atomic C layer) will cause an enhancement in the growth rate. On the other hand, the effect of B positioned in the other atomic C layers showed a decreased growth rate. These observations did not only correlate with experimental results but did also explain the anomalous variations in the diamond growth rate (i.e., either increase or decrease) with B doping.
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| 3. |
- Zou, Yiming, 1985-, et al.
(författare)
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Effect of Sulphur and Phosphorous Doping on the Growth Rate of CVD Diamond (111)
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731.
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Tidskriftsartikel (refereegranskat)abstract
- The purpose with the present study has been to theoretically investigate the effect of P (or S) doping on the diamond growth rate. The highly symmetric diamond (111) surface, terminated by H atoms, was thereby carefully investigated using density functional theory calculations under periodic boundary conditions. It was shown that both the thermodynamic and kinetic aspects of P (or S) doping during diamond growth will be severely affected by the dopants (as compared with the non-doped situations). More specifically, the results showed that P (positioned within the 2nd, 3rd or 4th layer), will cause an enhancement in the growth rate. On the other hand, any growth rate improvement do only occur when positioning S in the 4th atomic C layer. With S in atomic layers 1, 2 and 3, the growth rates were observed to decrease. These observations did correlate with experimental results.
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| 4. |
- Zou, Yiming, 1985-, et al.
(författare)
-
Effect of Sulphur and Phosphorous Doping on the Growth Rate of CVD Diamond (111)
-
Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731.
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose with the present study has been to theoretically investigate the effect of P (or S) doping on the diamond growth rate. The highly symmetric diamond (111) surface, terminated by H atoms, was thereby carefully investigated using density functional theory calculations under periodic boundary conditions. It was shown that both the thermodynamic and kinetic aspects of P (or S) doping during diamond growth will be severely affected by the dopants (as compared with the non-doped situations). More specifically, the results showed that P (positioned within the 2nd, 3rd or 4th layer), will cause an enhancement in the growth rate. On the other hand, any growth rate improvement do only occur when positioning S in the 4th atomic C layer. With S in atomic layers 1, 2 and 3, the growth rates were observed to decrease. These observations did correlate with experimental results.
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| 5. |
- Zou, Yiming, 1985-, et al.
(författare)
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Kinetic Study on the Growth of HFCVD B-doped Diamond
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The purpose with the present study has been to investigate the effect of trimethylborate on the diamond growth kinetics as a function of the boron carrier concentration in that diamond film. The kinetics of diamond hot filament CVD as a function of different gas compositions and various substrate temperatures were carefully studied. It was shown that the boron carrier concentration depended mainly on the boron concentration in the gas phase, but it is also various relative to the growth mechanism changes from surface kinetic to mass transport. However, trimethylborate did not alter the kinetics or HFCVD diamond growth mechanism at a measurable level. Moreover, Raman spectroscopy revealed that trimethylborate affected the quality of B-doped diamond films.
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| 6. |
- Zou, Yiming, 1985-
(författare)
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The Effect of Various Dopants on Diamond Growth : A Combined Experimental & Theoretical Approach
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diamond is a unique material with many exceptional properties. It has therefore been proven to be an important material for many applications. Moreover, the introduction of dopant species into the gas phase during the CVD growth process has been shown to strongly influence not only the properties and morphology of diamond, but also the growth rate. The purpose with the theoretical part of the present study has been to support and explain the experimental observations regarding the effect of various dopants (nitrogen, phosphorous, sulphur, and boron) on the diamond growth rate. Commonly observed H-terminated diamond surfaces [(111), (110) and (100)-2×1], were thereby carefully investigated using density functional theory under periodic boundary conditions. Based on the assumption that the hydrogen abstraction reaction is the growth rate-limiting step, both the thermodynamic and kinetic aspects of the diamond growth process were found to be severely affected by various dopants. More specifically, the results showed that nitrogen and phosphorous dopants (positioned within the 2nd, 3rd or 4th carbon layer) will cause an enhancement in the growth rate (as compared with non-doped situations). On the other hand, any growth rate improvement does only occur when positioning boron in the 2nd, and sulphur in the 4th, atomic carbon layer. With boron, and sulphur, positioned within the other atomic carbon layers, the growth rates were observed to decrease. In addition, the main purpose with the experimental part of the present study has been to investigate the effect of one specific dopant precursor (TMB) on the boron-doped diamond growth process. The result has shown that the increasing mass flow of TMB will not affect the mechanism of the HFCVD growth process of boron doped diamond. However, a linear boron carrier concentration in the diamond film vs. mass flow rate of TMB was observed.
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