Displaying publications 101 - 120 of 598 in total

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  1. Effect of synthesis condition on the growth of SWCNTs via catalytic chemical vapour deposition
    Toussi SM, Fakhru’L-Razi A, Luqman Chuah A, Suraya A
    Sains Malaysiana, 2011;40.
    Single-walled carbon nanotubes (SWCNTs) were synthesized by catalytic chemical vapor deposition (CCVD) of ethanol (C2H5OH) over Fe-Mo-MgO catalyst by using argon as a carrier gas. The reaction conditions are important factors that influence the yield and quality of carbon nanotubes. The effects of temperature and flow rate of carrier gas were investigated to increase the yield of carbon nanotubes. The synthesized carbon nanotubes were characterized by scanning electron microscopy, transmission electron microscopy, X-Ray diffraction and thermo-gravimetric analysis. The results showed that the growth of carbon nanotubes was effectively influenced by the reaction ambience and the synthesis condition. The temperature and flow rate of carrier gas played a key role in the yield and quality of synthesized CNTs. The estimated yield of synthesized carbon nanotubes was almost over 70%.
    Matched MeSH terms: X-Ray Diffraction
  2. Effects of Rf power on structural properties of Nc-Si:h thin films deposited by layer-by-layer (LBL) deposition technique
    Goh BT, Muhamad Rasat Muhamad, Saadah Abdul Rahman
    Sains Malaysiana, 2012;41:993-1000.
    The effects of rf power on the structural properties of hydrogenated nanocrystalline silicon (nc-Si:H) thin films deposited using layer-by-layer (LbL) deposition technique in a home-built plasma enhanced chemical vapor deposition (PECVD) system were investigated. The properties of the films were characterized by X-ray diffraction (XRD), microRaman scattering spectroscopy, high resolution transmission electron microscope (HRTEM) and Fourier transform infrared (FTIR) spectroscopy. The results showed that the films consisted of different size of Si crystallites embedded within an amorphous matrix and the growth of these crystallites was suppressed at higher rf powers. The crystalline volume fraction of the films was optimum at the rf power of 60 W and contained both small and big crystallites
    with diameters of 3.7 nm and 120 nm, respectively. The hydrogen content increased with increasing rf power and enhanced the structural disorder of the amorphous matrix thus decreasing the crystalline volume fraction of the films. Correlation of crystalline volume fraction, hydrogen content and structure disorder of the films under the effect of rf
    power is discussed.
    Matched MeSH terms: X-Ray Diffraction
  3. Characterization of residue from EFB and kenaf core fibres in the liquefaction process
    Sarani Zakaria, Rasidi Roslan, Umar Adli Amran, Chia CH, Saiful Bahari Bakaruddin
    Sains Malaysiana, 2014;43:429-435.
    Different type of fibers which is EFB and KC were liquefied in phenol with the presence of sulphuric acid as a catalyst. The liquefied residue was characterized by using Fourier transform infrared (FTIR) to determine the functional groups presents in both residues, X-ray diffraction (XRD) to determine the degree of crystallinity in the residue, thermogravimetric analysis (TGA) to analyze the thermal properties of the residue and scanning electron microscope (SEM) to investigate the structure and morphology of the residue. Phenol-to-EFB/KC ratio shows great effect on the amount of residue in the liquefaction process. Peak appearance can be observed in the FTIR analysis at 810 and 750 cm-1 which is attributed to the para and meta benzene, respectively or to be specific its associated to the p-alkyl phenol and m-alkyl phenol. In the XRD analysis, CrI of lignocellulosic materials increased after liquefaction process. Liquefaction process caused chemical penetration across the grain of the fiber, thus the fiber bundles started to separate into individual fibers shown in the SEM micrograph and the weights lost curve for both liquefied EFB and KC experienced three region decompositions.
    Matched MeSH terms: X-Ray Diffraction
  4. Dentine collagen cross-linking using tiopronin-protected Au/EDC nanoparticles formulations
    Daood U, Akram Z, Matinlinna JP, Fawzy AS
    Dent Mater, 2019 07;35(7):1017-1030.
    PMID: 31064669 DOI: 10.1016/j.dental.2019.04.005
    OBJECTIVE: The aim of this study was to investigate EDC-assisted collagen crosslinking effect with different concentrations of tiopronin-protected gold (TPAu) nanoparticles on demineralized dentine.

    METHODS: TPAu nanoparticles were fabricated from 0.31-g tetrachloroauric acid and 0.38-g of N-(2-mercaptopropionyl) glycine (2.4-mmol). Then co-dissolved using 35-mL of 6:1 methanol/acetic acid and mixed using NaBH4. EDC (0.3-M) was conjugated to TPAu nanoparticles at TPAU/EDC-0.25:1, and TPAU/EDC-0.5:1 treatment formulations ratios. Dentin specimens treated with 0.3-M EDC solution alone or left untreated were used as control. Nanoparticles formulations were characterized in term of particles morphology and size, Zeta potential, thermogravimetric analysis and small-angle X-ray scattering. Dentin substrates were characterized in term of TEM investigation, dentin proteases characterization, hydroxyproline liberation, elastic modulus measurement, Raman analysis and confocal microscopy viewing.

    RESULTS: TEM evaluation of tiopronin protected gold nanoparticles dispersion revealed nano-clusters formations in both groups. However, based on our TEM measurements, the particle-size was ranging from ˜20 to 50 nm with spherical core-shape which were almost similar for both TPAu/EDC ratios (0.5:1 and 0.25:1). Zeta potential measurements indicate negative nanoparticles surface charge. SAXS profiles for both formulations, suggest a typical profile for uni-lamellar nanoparticles. Superior dentin collagen cross-linking effect was found with the TPAu/EDC nanoparticles formulations compared to the control and EDC treated groups.

    SIGNIFICANCE: Cross-linking of dentin collagen using TPAu coupled with EDC through TPAu/EDC nanoparticles formulations is of potential significance in improving the biodegradation resistance, proteases inhibition, mechanical and structural stability of demineralized dentin substrates. In addition, the cross-linking effect is dependent on TPAu/EDC ratio, whereas higher cross-linking effect was found at TPAu/EDC ratio of 0.5:1.

    Matched MeSH terms: X-Ray Diffraction
  5. Catalytic study on TiO2 photocatalyst synthesised via microemulsion method on atrazine
    Ruslimie C, Hasmizam Razali, Wan M. Khairul
    Sains Malaysiana, 2011;40:1179-1186.
    Titanium dioxide photocatalyst was synthesised by microemulsions method under controlled hydrolysis of titanium butoxide, Ti(O(CH2)3)CH3. The synthesised TiO2 photocatalyst was compared with Sigma-commercial TiO2 by carrying out the investigation on its properties using scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis and thermal gravimetric analysis (TGA). The photocatalytic activities for both photocatalysts were studied for atrazine photodegradation.
    Matched MeSH terms: X-Ray Diffraction
  6. Properties enhancement of TPNR-MWNTS-OMMT hybrid nanocomposites by using ultrasonic treatment
    Mou‘ad A.Tarawneh, Sahrim Hj. Ahmad, Ku Zarina K, Ibrahim N. Hassan, Yu Lih jiun, Moayad Husein Flaifel, et al.
    Sains Malaysiana, 2013;42:503-507.
    The main goal of this paper was to study the effect of ultrasonic treatment time on the mechanical properties of thermoplastic natural rubber(TPNR) reinforced with hybrid MWNTs-OMMT. The intercalation of TPNR enhancement into layers of clay by increasing the d-spacing was found using X-ray diffraction. The tensile properties of nanocomposites treated with ultrasonic increased when compared with untreated nanocomposites. The optimum ultrasonic treatment time was obtained at 3 h. The transmission electron microscope micrograph showed a combination of intercalated-exfoliated structure of the TPNR composites with organic clay and dispersion of MWNTs. The ultrasonic treatment can promote the dispersion of MWNTs-OMMT in TPNR and also improved the compatibility of hybrid filler and the TPNR matrix.
    Matched MeSH terms: X-Ray Diffraction
  7. Structural properties of zinc oxide thin films deposited on various substrates
    Ching C, Om P, Ng S, Hassan Z, Abu Hassan H, Abdullah M
    Sains Malaysiana, 2014;43:923-927.
    In this work, the structural properties of radio frequency sputtering-grown zinc oxide (ZnO) thin films on sapphire (Al203), gallium arsenide (GaAs) and n-type silicon (Si) substrates were characterized. Scanning electron microscopy was employed to study the surface morphology of the samples. X-ray diffraction (xRD) measurements were also performed to obtain the structural information of the samples. The xRD results showed that the ZnO layers grown on different substrates have similar lattice constant (c) values, which were used to calculate the strain percentages of the ZnO thin films. The surface morphologies of the ZnO thin films indicated the formation of a granular surface when ZnO is deposited on n-type Si(100) and Si( 111 ) substrates. Meanwhile, a leaf-like surface is obtained when ZnO is deposited on GaAs and Al203 substrates. The results showed that the ZnO thin film grown on n-type Si(100) has the best quality among all the samples.
    Matched MeSH terms: X-Ray Diffraction
  8. Characterizations of cupric oxide thin films on glass and silicon substrates by radio frequency magnetron sputtering
    Ooi P, Ching C, Ahmad M, Ng S, Abdullah M, Abu Hassan H, et al.
    Sains Malaysiana, 2014;43:617-621.
    Cupric oxide (CuO) thin films were prepared on a glass and silicon (Si) substrates by radio frequency magnetron sputtering system. The structural, optical and electrical properties of CuO films were characterized by X-ray diffraction (xRD), atomic force microscopy (AFM), Fourier transform infrared spectrometer, ultra-violet visible spectrophotometer, respectively, four point probe techniques and Keithley 4200 semiconductor characterization system. The xRD result showed that single phase CuO thin films with monoclinic structure were obtained. AFM showed well organized nano-pillar morphology with root mean square surface roughness for CuO thin films on glass and Si substrates were 3.64 and 1.91 nm, respectively. Infrared reflectance spectra shown a single reflection peak which is corresponding to CuO optical phonon mode and it confirmed that only existence of CuO composition on both substrates. The optical direct band gap energy of the CuO film grown on glass substrate, which is calculated from the optical transmission measurement was 1.37 eV. Finally, it was found that the deposited CuO films are resistive and the palladium formed ohmic contact for CuO on glass and schottky contact for CuO on Si.
    Matched MeSH terms: X-Ray Diffraction
  9. Characterization of the feedstock properties of metal injection-molded WC-Co with palm stearin binder system
    Sri Yulis M. Amin, Norhamidi Muhamad, Khairur Rijal Jamaludin, Fayyaz A, Heng SY
    Sains Malaysiana, 2014;43:123-128.
    Feedstock preparation, as well as its characterization, is crucial in the production of highly sintered parts with minimal defect. The hard metal powder - particularly, cemented carbide (wc-co) used in this study was investigated both physically and thermally to determine its properties before the mixing and injection molding stage. Several analyses were conducted, such as scanning electron microscopy, energy dispersive X-ray diffraction, pycnometer density, critical powder volume percentage (cPvP), as well as thermal tests, such as thermogravimetric analysis and differential scanning calorimetry. On the basis of the CPVP value, the feedstock, consisting of wc-co powder, was mixed with 60% palm stearin and 40% polyethylene at an optimal powder loading, within 2 to 5% lower than the CPVP value. The CPVP spotted value was 65%. The feedstock optimal value at 61% showed good rheological properties (pseudoplastic behavior) with an n value lower than 1, considerably low activation energy and high moldability index. These preliminary properties of the feedstock serve as a benchmark in designing the schedule for the next whole steps (i.e. injection, debinding and sintering processes).
    Matched MeSH terms: X-Ray Diffraction
  10. Fulltext Amino Anthraquinone: Synthesis, Characterization, and Its Application as an Active Material in Environmental Sensors
    Ali S, Tahir M, Mehboob N, Wahab F, J Langford S, Mohd Said S, et al.
    Materials (Basel), 2020 Feb 21;13(4).
    PMID: 32098037 DOI: 10.3390/ma13040960
    This work reports synthesis, thin film characterizations, and study of an organic semiconductor 2-aminoanthraquinone (AAq) for humidity and temperature sensing applications. The morphological and phase studies of AAq thin films are carried out by scanning electron microscope (SEM), atomic force microscope (AFM), and X-ray diffraction (XRD) analysis. To study the sensing properties of AAq, a surface type Au/AAq/Au sensor is fabricated by thermally depositing a 60 nm layer of AAq at a pressure of ~10-5 mbar on a pre-patterned gold (Au) electrodes with inter-electrode gap of 45 µm. To measure sensing capability of the Au/AAq/Au device, the variations in its capacitance and resistance are studied as a function of humidity and temperature. The Au/AAq/Au device measures and exhibits a linear change in capacitance and resistance when relative humidity (%RH) and temperature are varied. The AAq is a hydrophobic material which makes it one of the best candidates to be used as an active material in humidity sensors; on the other hand, its high melting point (575 K) is another appealing property that enables it for its potential applications in temperature sensors.
    Matched MeSH terms: X-Ray Diffraction
  11. Fulltext Design of next-generation ceramic fuel cells and real-time characterization with synchrotron X-ray diffraction computed tomography
    Li T, Heenan TMM, Rabuni MF, Wang B, Farandos NM, Kelsall GH, et al.
    Nat Commun, 2019 04 02;10(1):1497.
    PMID: 30940801 DOI: 10.1038/s41467-019-09427-z
    Ceramic fuel cells offer a clean and efficient means of producing electricity through a variety of fuels. However, miniaturization of cell dimensions for portable device application remains a challenge, as volumetric power densities generated by readily-available planar/tubular ceramic cells are limited. Here, we demonstrate a concept of 'micro-monolithic' ceramic cell design. The mechanical robustness and structural integrity of this design is thoroughly investigated with real-time, synchrotron X-ray diffraction computed tomography, suggesting excellent thermal cycling stability. The successful miniaturization results in an exceptional power density of 1.27 W cm-2 at 800 °C, which is among the highest reported. This holistic design incorporates both mechanical integrity and electrochemical performance, leading to mechanical property enhancement and representing an important step toward commercial development of portable ceramic devices with high volumetric power (>10 W cm-3), fast thermal cycling and marked mechanical reliability.
    Matched MeSH terms: X-Ray Diffraction
  12. Synthesis of zinc selenide/graphene oxide composite via direct and indirect hydrothermal method
    Kee LH, Ying Chyi JL, Zainal Abidin Talib, Mohammad Shuhazlly Mamat, Hong Ngee JL, Fakhrurrazi Ashari, et al.
    Sains Malaysiana, 2016;45:1201-1206.
    Zinc selenide/graphene oxide (ZnSe/GO) composite is synthesized using hydrothermal method. Two different methods
    such as direct and indirect route have been investigated to form the ZnSe/GO composite. In this research, the graphene
    oxide used was in sheet and liquid form. The synthesized composite was then characterized using X-ray diffraction (XRD)
    for phase identification, field emission scanning electron microscopy (FESEM) for morphology analysis and ultravioletvisible
    spectroscopy (UV-Vis) for optical properties. ZnSe/GO composite showed absorption peak ranging from 460 to
    480 nm with the optical band gap obtained through Tauc equation. The optical band gap of the ZnSe/GO composite has
    been tuned down to a smaller value as compared to the bulk ZnSe compound. The optical band gap has been reduced
    to around 2.53 eV when liquid graphene oxide was used while around 2.23 to 2.32 eV when graphene oxide sheet was
    used. The purity of ZnSe/GO composite synthesis via indirect hydrothermal method is higher than those synthesized via
    direct hydrothermal method. The type of graphene oxide will affect the morphology of the composite where the ZnSe
    compound was either wrapped by tiny thorn-like substance or graphene oxide layer.
    Matched MeSH terms: X-Ray Diffraction
  13. Production and characterization of the defatted oil palm shell nanoparticles
    Abdul Khalil HPS, Md. Sohrab Hossain, Nur Amiranajwa AS, Nurul Fazita MR, Mohamad Haafiz MK, Suraya N, et al.
    Sains Malaysiana, 2016;45:833-839.
    This present study was conducted to produce defatted oil palm shell (OPS) nanoparticles. Wherein, the OPS nanoparticles
    were defatted by solvent extraction method. Several analytical methods including transmission electron microscope (TEM),
    X-ray diffraction (XRD), particle size analyzer, scanning electron microscope (SEM), SEM energy dispersive X-ray (SEM-EDX)
    and thermal gravimetric analyzer (TGA) were used to characterize the untreated and defatted OPS nanoparticles. It was
    found that 75.3% OPS particles were converted into nanoparticles during ball milling. The obtained OPS nanoparticles had
    smaller surface area with angular, irregular and crushed shapes under SEM view. The defatted OPS nanoparticles did not
    show any agglomeration during TEM observation. However, the untreated OPS nanoparticles had higher decomposition
    temperature as compared to the defatted OPS nanoparticles. Based on the characterization results of the OPS nanoparticles,
    it is evident that the defatted OPS nanoparticles has the potentiality to be used as filler in biocomposites
    Matched MeSH terms: X-Ray Diffraction
  14. Influence of hydrochloric acid volume on the growth of titanium dioxide (TiO2) nanostructures by hydrothermal method
    Noor Kamalia Abd Hamed, Noor Sakinah Khalid, Fatin Izyani Mohd Fazli, Muhammad Luqman Mohd Napi, Nafarizal Nayan, Mohd Khairul Ahmad
    Sains Malaysiana, 2016;45:1669-1673.
    Titanium dioxide (TiO2
    ) with various morphologies has been successfully synthesized by a simple hydrothermal method
    at 150o
    C for 10 h using titanium butoxide (TBOT) as a precursor, deionized (DI) water and hydrochloric acid (HCl) on
    a fluorine-doped tin oxide (FTO) substrate. The influences of HCl volume on structural and morphological properties
    of TiO2
    have been studied using x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM),
    respectively. The result showed that several morphologies such as microsphere, microrods, nanorods and nanoflowers
    were obtained by varying the volume of hydrochloric acid. The crystallinity of titanium dioxide enhanced with the
    increasing of hydrochloric acid volume.
    Matched MeSH terms: X-Ray Diffraction
  15. Facile synthesis of AgCl/BiYO3 composite for efficient photodegradation of RO16 under UV and visible light irradiation
    Sirimahachai R, Harome H, Wongnawa S
    Sains Malaysiana, 2017;46:1393-1399.
    AgCl/BiYO3
    composite was successfully synthesized via the aqueous precipitation method followed by calcination. The
    varied amount of AgCl (10, 20 and 30%) was mixed into BiYO3
    via sonochemical-assisted method. The structures and
    morphologies of the as-prepared AgCl/BiYO3
    composite were characterized by x-ray diffraction (XRD), scanning electron
    microscopy (SEM) and UV-vis diffused reflectance spectroscopy (UV-vis DRS). The optical absorption spectrum of AgCl/
    BiYO3
    composite showed strong absorption in visible region. The photocatalytic activity of AgCl/BiYO3
    composite was
    evaluated by the photodegradation of reactive orange16 (RO16), which was selected to represent the dye pollutants,
    under UV and visible light irradiation. The results indicated that 20% AgCl/BiYO3 photocatalyst was the most capable
    photocatalyst in this series in the degradation of RO16 under both UV and visible light illumination within 1 h. Moreover,
    the mechanism of photocatalytic degradation of AgCl/BiYO3
    was elucidated using three types of free radical scavengers.
    The significant enhancement was attributed to the formation of AgCl/BiYO3
    heterojunction resulting in the low electronhole
    pair recombination rate.
    Matched MeSH terms: X-Ray Diffraction
  16. Fulltext Biophysical Evaluation of Water-Soluble Curcumin Encapsulated in β-Cyclodextrins on Colorectal Cancer Cells
    Low ZX, Teo MYM, Nordin FJ, Dewi FRP, Palanirajan VK, In LLA
    Int J Mol Sci, 2022 Oct 25;23(21).
    PMID: 36361655 DOI: 10.3390/ijms232112866
    Curcumin (CUR), a curcuminoid originating from turmeric root, possesses diverse pharmacological applications, including potent anticancer properties. However, the use of this efficacious agent in cancer therapy has been limited due to low water solubility and poor bioavailability. To overcome these problems, a drug delivery system was established as an excipient allowing improved dispersion in aqueous media coupled with enhanced in vitro anticancer effects. Different analyses such as UV-vis spectroscopy, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), solubility and dissolution assays were determined to monitor the successful encapsulation of CUR within the inner cavity of a β-cyclodextrin (β-CD) complex. The results indicated that water solubility was improved by 205.75-fold compared to pure CUR. Based on cytotoxicity data obtained from MTT assays, the inclusion complex exhibited a greater decrease in cancer cell viability compared to pure CUR. Moreover, cancer cell migration rates were decreased by 75.5% and 38.92%, invasion rates were decreased by 37.7% and 35.7%, while apoptosis rates were increased by 26.3% and 14.2%, and both caused caspase 3 activation toward colorectal cancer cells (SW480 and HCT116 cells). This efficacious formulation that enables improved aqueous dispersion is potentially useful and can be extended for various chemotherapeutic applications. Preliminary toxicity evaluation also indicated that its composition can be safely used in humans for cancer therapy.
    Matched MeSH terms: X-Ray Diffraction
  17. Size-Controlled and Optical Properties of Platinum Nanoparticles by Gamma Radiolytic Synthesis
    Gharibshahi E, Saion E, Ashraf A, Gharibshahi L
    Appl Radiat Isot, 2017 Dec;130:211-217.
    PMID: 29028581 DOI: 10.1016/j.apradiso.2017.09.012
    Gamma radiolytic synthesis was used to produce size-controlled spherical platinum nanoparticles from an aqueous solution containing platinum tetraammine and polyvinyl pyrrolidone. The structural characterizations were performed using X-ray diffraction, and transmission electron microscopy. The transmission electron microscopy was used to determine the average particle diameter, which decreased from 4.4nm at 80kGy to 2.8nm at 120kGy. The UV-visible absorption spectrum was measured and found that platinum nanoparticles exhibit two steady absorption maxima in UV regions due to plasmonic excitation of conduction electrons, which blue shifted to lower wavelengths with a decrease in particle size. We consider the conduction electrons of platinum nanoparticles to follow Thomas-Fermi-Dirac-Weizsacker atomic model that they are not entirely free but weakly bounded to particles at lower-energy states {n = 5, l = 2 or 5d} and {n = 6, l = 0 or 6s}, which upon receiving UV photon energy the electrons make intra-band quantum excitations to higher-energy states allowed by the principles of quantum number that results the absorption maxima. We found an excellent agreement between the experimental and theoretical results, which suggest that the optical absorption of metal nanoparticles could be fundamentally described by a quantum mechanical interpretation, which could be more relevant to photo-catalysis and heterogeneous catalysis.
    Matched MeSH terms: X-Ray Diffraction
  18. Effect of Milling Time on the Microstructure, Physical and Mechanical Properties of Al-Al₂O₃ Nanocomposite Synthesized by Ball Milling and Powder Metallurgy
    Toozandehjani M, Matori KA, Ostovan F, Abdul Aziz S, Mamat MS
    Materials (Basel), 2017 Oct 26;10(11).
    PMID: 29072632 DOI: 10.3390/ma10111232
    The effect of milling time on the morphology, microstructure, physical and mechanical properties of pure Al-5 wt % Al₂O₃ (Al-5Al₂O₃) has been investigated. Al-5Al₂O₃ nanocomposites were fabricated using ball milling in a powder metallurgy route. The increase in the milling time resulted in the homogenous dispersion of 5 wt % Al₂O₃ nanoparticles, the reduction of particle clustering, and the reduction of distances between the composite particles. The significant grain refining during milling was revealed which showed as a reduction of particle size resulting from longer milling time. X-Ray diffraction (XRD) analysis of the nanocomposite powders also showed that designated ball milling contributes to the crystalline refining and accumulation of internal stress due to induced severe plastic deformation of the particles. It can be argued that these morphological and microstructural variations of nanocomposite powders induced by designated ball milling time was found to contribute to an improvement in the density, densification, micro-hardness (HV), nano-hardness (HN), and Young's modulus (E) of Al-5Al₂O₃ nanocomposites. HV, HN, and E values of nanocomposites were increased by ~48%, 46%, and 40%, after 12 h of milling, respectively.
    Matched MeSH terms: X-Ray Diffraction
  19. Fulltext Impact of Sulfuric Acid Treatment of Halloysite on Physico-Chemic Property Modification
    Gaaz TS, Sulong AB, Kadhum AAH, Nassir MH, Al-Amiery AA
    Materials (Basel), 2016 Jul 26;9(8).
    PMID: 28773741 DOI: 10.3390/ma9080620
    Halloysite (HNT) is treated with sulfuric acid and the physico-chemical properties of its morphology, surface activity, physical and chemical properties have been investigated when HNT is exposed to sulfuric acid with treatment periods of 1 h (H1), 3 h (H3), 8 h (H8), and 21 h (H21). The significance of this and similar work lies in the importance of using HNT as a functional material in nanocomposites. The chemical structure was characterized by Fourier transform infrared spectroscopy (FTIR). The spectrum demonstrates that the hydroxyl groups were active for grafting modification using sulfuric acid, promoting a promising potential use for halloysite in ceramic applications as filler for novel clay-polymer nanocomposites. From the X-ray diffraction (XRD) spectrum, it can be seen that the sulfuric acid breaks down the HNT crystal structure and alters it into amorphous silica. In addition, the FESEM images reveal that the sulfuric acid treatment dissolves the AlO₆ octahedral layers and induces the disintegration of SiO₄ tetrahedral layers, resulting in porous nanorods. The Bruncher-Emmett-Teller (BET) surface area and total pore volume of HNTs showed an increase. The reaction of the acid with both the outer and inner surfaces of the nanotubes causes the AlO₆ octahedral layers to dissolve, which leads to the breakdown and collapse of the tetrahedral layers of SiO₄. The multi-fold results presented in this paper serve as a guide for further HNT functional treatment for producing new and advanced nanocomposites.
    Matched MeSH terms: X-Ray Diffraction
  20. Fulltext Interfaces between hexagonal and cubic oxides and their structure alternatives
    Zhou H, Wu L, Wang HQ, Zheng JC, Zhang L, Kisslinger K, et al.
    Nat Commun, 2017 11 14;8(1):1474.
    PMID: 29133800 DOI: 10.1038/s41467-017-01655-5
    Multi-layer structure of functional materials often involves the integration of different crystalline phases. The film growth orientation thus frequently exhibits a transformation, owing to multiple possibilities caused by incompatible in-plane structural symmetry. Nevertheless, the detailed mechanism of the transformation has not yet been fully explored. Here we thoroughly probe the heteroepitaxially grown hexagonal zinc oxide (ZnO) films on cubic (001)-magnesium oxide (MgO) substrates using advanced scanning transition electron microscopy, X-ray diffraction and first principles calculations, revealing two distinct interface models of (001) ZnO/(001) MgO and (100) ZnO/(001) MgO. We have found that the structure alternatives are controlled thermodynamically by the nucleation, while kinetically by the enhanced Zn adsorption and O diffusion upon the phase transformation. This work not only provides a guideline for the interface fabrication with distinct crystalline phases but also shows how polar and non-polar hexagonal ZnO films might be manipulated on the same cubic substrate.
    Matched MeSH terms: X-Ray Diffraction
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