Effect of mechanical treatment on properties of cellulose nanofibrils produced from bleached hardwood and softwood pulps

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

The structural, morphological and optical studies on BaAl2O4/MgAl2O4/MgO:x% Gd3+ (0 ≤ x ≤ 1.1) mixed phases synthesized by sol-gel method

DATA AVAILABILITY : Data will be made available on request.Please read abstract in the article.The South African National Research Foundation (NRF) Thuthuka programme, NRF incentive funding for rated researchers (IPRR), SMU Physics department research fund and SMU Electron Microscope Unit.https://www.elsevier.com/locate/physbhj2024PhysicsNon

Effects of varying Sm3+ concentration on the structure, morphology and photoluminescence properties of the BaAl2O4 /CaAl2O4/Ca4Al6O13/Ca3Al2O6:x% Sm3+ (0 ≤ x ≤ 1.9) mixed phases using citrate sol-gel method

DATA AVAILABILITY STATEMENT : Data will be made available on request.Please read abstract in the article.The South African National Research Foundation (NRF) Thuthuka programme, NRF incentive funding for rated researchers (IPRR).http://www.cell.com/heliyonhj2023PhysicsNon

Analysis of Nd3+ concentration on the structure, morphology and photoluminescence of sol-gel Sr3ZnAl2O7 nanophosphor

Neodymium activated strontium zinc aluminate (Sr3ZnAl2O7:x%Nd3+) nanophosphor was synthesized using the sol-gel technique whereby the Nd3+ concentration was varied in the range 0 ≤ x ≤ 2. The effect of Nd3+ concentration on the structure, particle morphology and photoluminescence properties of Sr3ZnAl2O7 were investigated. The X-ray diffraction (XRD) results revealed that all samples resembled the mixture of both ZnAl2O4 and Sr3Al2O6 cubic structures. Nd3+ doping influenced the crystallite sizes of the prepared phosphor materials. The energy dispersive X-ray spectroscopy (EDS) results confirmed the presence of all expected elements in the composition. Scanning electron microscopy (SEM) revealed that as the Nd3+ concentration increased the surface morphology changed to smooth mountain-like structures. The ultraviolet–visible (UV–Vis) diffuse reflection spectroscopy showed that the band gap of Sr3ZnAl2O7 can be tuned from 2.74 to 2.95 eV by increasing the Nd3+ concentration. When the host is excited above the bandgap (374 nm), broad emission attributed to defects occurs with the maximum near 585 nm. Doped samples excited in this manner do not exhibit additional luminescence due to the Nd3+ ions, but in contrast there is a small dip in the defect emission band near 585 nm due to absorption attributed to Nd3+ ions. Characteristic infrared emissions of Nd3+ ions at 885, 1064 and 1340 nm were observed by directly exciting the Nd3+ ions at 585 nm (4I9/2 → 5G5/2 + 2G7/2) and were attributed to 4F3/2 → 4I9/2, 4I11/2 and 4I13/2 transitions, respectively. The Commission Internationale de l’Eclairage (CIE) coordinates results showed that the orange emission colour is from the host. Keywords: Sol-gel, Nd3+ activated, Sr3ZnAl2O7, Photoluminescence, CI

Effect of mechanical treatment on properties of cellulose nanofibrils produced from bleached hardwood and softwood pulps

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