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38. Effects of varying Alxmoles on structure and luminescence properties of ZnAlxO1.5x+1:0.1 mol% Tb3+nanophosphors prepared using citrate sol–gel method

Author

Maphiri, V.M., Melato, L.T., Mhlongo, M.R., Hlatshwayo, T.T., Motaung, T.E., Koao, L.F., and Motloung, S.V.

Abstract

Un-doped and ZnAlxO1.5x+1:0.1 mol% Tb3+(ZAOT) nano-powders were synthesized via citrate sol-gel method. The Alxmoles were varied in the range of 0.25 ≤ x ≤ 5.0. The X-ray powder diffraction (XRD) data reveal that for x < 1.5, the prepared samples crystal structure consists of mixed phases of the cubic ZnAl2O4and hexagonal ZnO phases, while for x ≥ 1.5 the structure consists of single phase of cubic ZnAl2O4. The Raman and Fourier-transform infrared (FTIR) vibrational spectroscopy show the presence of vibrations emanating ZnAl2O4spinel. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show the presence of irregular sphere at x≥2.0 attributed to ZnAl2O4. The photoluminescence (PL) spectroscopy reveals emissions from both the host and Tb3+transitions. Emissions from Tb3+are observed at 382, 414, 439, 458 nm and 489, 545, 585, 621 nm, which were attributed to the 5D3→ 7F6,5,4,2and 5D4→ 7F6,5,4,3, respectively. The results confirm that the Tb3+occupation site depends on the Alxmoles. The International Commission on Illumination (CIE) colour chromaticity shows that the emission colour can be tuned from blue to green by varying the Alxmoles.

Published
2023
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43. Effect of mechanical treatment on properties of cellulose nanofibrils produced from bleached hardwood and softwood pulps

Author

Lekha, P., Mtibe, A., Motaung, T.E., Andrew, Jerome E., Sithole, B. Bruce, Gibril, M., Lekha, P., Mtibe, A., Motaung, T.E., Andrew, Jerome E., Sithole, B. Bruce, and Gibril, M.

Abstract

Bleached hardwood and softwood South African kraft pulps were passed through a commercially available micro grinder for varying number of passes and the properties of the resultant pulps were assessed periodically using microscopy, Fourier transform infrared spectroscopy (FTIR), X-ray crystallography (XRD) and Thermogravimetric analysis (TGA). The ultrastructural analysis of the pulp fibres revealed that after 120 passes both hardwood and softwood bleached fibres showed the presence of cellulose nanofibres (CNFs). The FTIR analysis showed no modification to the cellulose structure and side groups upon treatment with the supermasscolloider (SMC). Both hardwood and softwood pulp fibres showed a decline in crystallinity after SMC treatment. For the hardwood pulps there were no major differences between the untreated pulps and those passed through the SMC. In the case of the softwood pulps, the SMC treatment resulted in more thermally stable CNFs compared with the untreated bleached pulps. This was observed at several levels of treatment (40, 120 and 200 passes). After 200 passes both the hardwood and softwood kraft pulp fibres produced CNFs with an average width of 11 nm and lengths with several micrometers.

Published
2016

46. Investigating the effects of varying sulfur concentration on ZnSxSe1-x(0 ≤ x ≤ 1.0) thin films prepared by photo-assisted chemical bath method

Author

Hile, D.D., Swart, H.C., Motloung, S.V., Motaung, T.E., Ahemen, I., Jubu, P.R., Essien, K.E., and Koao, L.F.

Abstract

•ZnSxSe1-x(0 ≤ x ≤ 1.0) thin films were deposited on glass slide at 80 ℃ for 2 h.•Photo-assisted chemical bath technique was used for the deposition.•The films were annealed in air at temperatures of 250 ℃ for 3 h.•The films structure transformed from wurtizite ZnSe to Cubic ZnS as x varies from 0 to 1.0.•The thin films emission colour was tunable making them good candidates for luminescent devices applications.

Published
2024
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49. The effect of acid content on the poly(furfuryl) alcohol/cellulose composites.

Author

Motaung, T.E., Gqokoma, Z., Linganiso, L.Z., and Hato, M.J.

Subjects
*FURFURYL alcohol, *CELLULOSE fibers, *COMPOSITE materials, *SULFONIC acids, *POLYMERIZATION, *COTTON fibers, *THERMOGRAVIMETRY, *THERMAL stability
Abstract

Cellulose/poly(furfuryl alcohol) (PFA) composites were prepared via in situ polymerization process using p-toulene sulfonic acid as a catalyst. Cellulose was extracted from cotton fibers using chemical treatments with basic media of NaOH, NaClO2 and KOH. Acid hydrolysis at different concentrations (30, 40 and 50%) of sulphuric acid was used and the final suspended cellulose was incorporated in PFA. The treatments of the cotton fibers ensued to higher crystalline cellulose which was proportional to sulphuric acid contents. Scanning electron microscopy studies (SEM) results showed a poor interfacial interaction when 50% acid content was used for hydrolyses. The effect of fiber reinforcement on thermal and dynamic mechanical properties of the composites was investigated using thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMTA). The TGA results showed higher thermal stability of cellulose/PFA composites as compared to the neat PFA. The DMA results showed that the incorporation of the cellulose fibers imparts significant enhancement in the storage modulus of the PFA matrix. There was also the clear decrease in intensity of the tan peak of the composites compared to the neat PFA. POLYM. COMPOS., 37:2434-2441, 2016. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Published
2016
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