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University of the Western Cape

1. Pepenene, Refuoe Donald. Macroscopic and Microscopic surface features of Hydrogenated silicon thin films .

Degree: 2018, University of the Western Cape

An increasing energy demand and growing environmental concerns regarding the use of fossil fuels in South Africa has led to the challenge to explore cheap, alternative sources of energy. The generation of electricity from Photovoltaic (PV) devices such as solar cells is currently seen as a viable alternative source of clean energy. As such, crystalline, amorphous and nanocrystalline silicon thin films are expected to play increasingly important roles as economically viable materials for PV development. Despite the growing interest shown in these materials, challenges such as the partial understanding of standardized measurement protocols, and the relationship between the structure and optoelectronic properties still need to be overcome. Advisors/Committee Members: Muller, Theo (advisor).

Subjects/Keywords: Hot-wire chemical vapour deposition (HWCVD); Hydrogenated amorphous silicon (a-Si: H); Hydrogenated nanocrystalline silicon (nc-Si: H); Hydrogen dilution; Nano-structural properties; Root mean square (rms) roughness; Dielectric functions; Band gap; Refractive index; Bruggeman Effective Medium Approximations (BEMA); Traceability; Optical modelling

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Pepenene, R. D. (2018). Macroscopic and Microscopic surface features of Hydrogenated silicon thin films . (Thesis). University of the Western Cape. Retrieved from http://hdl.handle.net/11394/6414

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Pepenene, Refuoe Donald. “Macroscopic and Microscopic surface features of Hydrogenated silicon thin films .” 2018. Thesis, University of the Western Cape. Accessed May 31, 2020. http://hdl.handle.net/11394/6414.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Pepenene, Refuoe Donald. “Macroscopic and Microscopic surface features of Hydrogenated silicon thin films .” 2018. Web. 31 May 2020.

Vancouver:

Pepenene RD. Macroscopic and Microscopic surface features of Hydrogenated silicon thin films . [Internet] [Thesis]. University of the Western Cape; 2018. [cited 2020 May 31]. Available from: http://hdl.handle.net/11394/6414.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Pepenene RD. Macroscopic and Microscopic surface features of Hydrogenated silicon thin films . [Thesis]. University of the Western Cape; 2018. Available from: http://hdl.handle.net/11394/6414

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

2. Hunnicutt, William. Characterization of calcium-silicate-hydrate and calcium-alumino-silicate-hydrate.

Degree: MS, 0106, 2013, University of Illinois – Urbana-Champaign

The primary objectives of this thesis were to synthesize calcium silicate hydrate (C-S-H) and calcium aluminosilicate hydrate (C-A-S-H) and characterize their structures with varying Ca/Si ratios and aluminum content. As a secondary objective, carbonation behavior in synthesized C-S-H was studied. C-S-H was synthesized in the lab using two different methods: the double decomposition of calcium nitrate and sodium silicate solutions, and the direct reaction between calcium oxide and fumed silica in water. In C-A-S-H the source of aluminum was sodium aluminate or aluminum nitrate. A variety of phases were present depending on the degree of carbonation of the C-S-H or C-A-S-H. C-S-H, C-A-S-H, alumina/silica gel, calcite, aragonite, and vaterite were all observed throughout the course of study. X-ray diffraction (XRD) was the technique used to identify these phases. XRD was also used to explore the changes in crystal structure with varying Ca/Si ratios and aluminum content. No significant changes to the crystal structure were found. The effect of Ca/Si ratio, aluminum content, and synthesis method were studied on the molecular scale using 29Si and 27Al nuclear magnetic resonance spectroscopy (NMR). An increasing Ca/Si ratio has the effect of a shorter alumino-silicate chain length and an increase in aluminum content increases the alumino-silicate chain length. Aluminum substitution occurred primarily in the bridging tetrahedron position, but also in the pairing tetrahedron position. Aluminum uptake was also examined with respect with Ca/Si ratio and was found to decrease with increasing Ca/Si ratio. The changes in chemical environment of the iii aluminum ion with varying Ca/(Si+Al) ratios was also observed by 27Al NMR. It was found that as the Ca/(Si+Al) ratio increased, the amount of chemical shielding of the 27Al nuclei decreased . Carbonation of C-S-H was also examined and it was found that the double decomposition synthesis method allows for more rapid carbonation of the CS- H. The source of increased carbonation rate is the high pH of the solutions. Advisors/Committee Members: Struble, Leslie J. (advisor).

Subjects/Keywords: calcium silicate hydrate (C-S-H); calcium aluminosilicate hydrate (C-A-S-H); nuclear magnetic resonance spectroscopy (NMR); Carbonation; Ca/Si

A-S-H was studied when varying these ratios. Additionally, the effect of Ca/Si ratio on… …spectroscopy, the molecular structure of C-S-H and C-A-S-H with varying Ca/Si and Al/Si ratios, and… …has been observed that C-S-H has a variable stoichiometry with Ca/Si ratio in the range of… …The crystal cell dimensions of the C-S-H varied with Ca/Si ratios. The ‘a’ dimension… …x28;1Al) 2 Sun et al. [2] synthesized C-A-S-H with Ca/(Al+Si) ratios… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Hunnicutt, W. (2013). Characterization of calcium-silicate-hydrate and calcium-alumino-silicate-hydrate. (Thesis). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/45395

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Hunnicutt, William. “Characterization of calcium-silicate-hydrate and calcium-alumino-silicate-hydrate.” 2013. Thesis, University of Illinois – Urbana-Champaign. Accessed May 31, 2020. http://hdl.handle.net/2142/45395.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Hunnicutt, William. “Characterization of calcium-silicate-hydrate and calcium-alumino-silicate-hydrate.” 2013. Web. 31 May 2020.

Vancouver:

Hunnicutt W. Characterization of calcium-silicate-hydrate and calcium-alumino-silicate-hydrate. [Internet] [Thesis]. University of Illinois – Urbana-Champaign; 2013. [cited 2020 May 31]. Available from: http://hdl.handle.net/2142/45395.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Hunnicutt W. Characterization of calcium-silicate-hydrate and calcium-alumino-silicate-hydrate. [Thesis]. University of Illinois – Urbana-Champaign; 2013. Available from: http://hdl.handle.net/2142/45395

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.