Khor Shing Fhan
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Preferred name
Khor Shing Fhan
Official Name
Shing Fhan, Khor
Alternative Name
Khor, S. F.
Fhan, Khor Shing
Shing, Fhan Khor
Khor, Shing F.
Shing Fhan, Khor
Main Affiliation
Scopus Author ID
35242874900
Researcher ID
W-7216-2019

Research Output
Now showing 1 - 7 of 7
  • Publication
    Formation of bio-based derived dicalcium silicate ceramics via mechanochemical treatment: physical, XRD, SEM and FTIR analyses
    ( 2023-07)
    Siti Nur Hazwani Yunus
    ;
    Khor Shing Fhan
    ;
    Banjuraizah Johar
    ;
    Nur Maizatul Shima Adzali
    ;
    Nur Hazlinda Jakfar
    ;
    Cheng Ee Meng
    ;
    Emma Ziezie Mohd Tarmizi
    ;
    Zainal Abidin Talib
    Beta-dicalcium silicate plays an important role in modern technology, but its tendency for polymorphic transformation results in the dusting phenomenon, is a major challenge. Therefore, mechanochemical treatment is used to reduce the particle size to retain the stability of the polymorph. In this study, pure dicalcium silicate ceramics of β-monoclinic structure with P 121/c1 space group were synthesized using calcium oxide and silicate powders derived from calcined eggshells and rice husks, respectively. The powders were mixed in a 2:1 molar ratio by mechanochemical treatment and heat-treated in the air at temperatures ranging from 900°C to 1100°C for 2 h. The results reveal that pure betadicalcium silicate formed at 1100°C without adding stabilizers. The properties of the pristine and sintered bodies were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). SEM revealed that the grain and pore sizes increase with rising sintering temperatures. FTIR spectra indicate the existence of Si-O bonds in -4 4 SiO tetrahedrons on all the samples. The sample sintered at 1000°C attains the lowest bulk density (1.2463 g/cm3), whereas the apparent porosity is the highest (62.5%). The reason for this trend is due to the decomposition of carbonate into CO2 gas. The densification onset for the sample sintered at 1100°C as the bulk density rises and grain size achieves 6.06 μm. This study further explains the effect of sintering temperatures on the physical, structural, and morphological properties of Ca2SiO4 which would also be useful for further optimization of its use.
  • Publication
    Synthesis of sustainable binary Calcium monosilicate ceramics from bio-waste: effect of sintering temperature on microstructure and electrical properties
    (Universiti Malaysia Perlis (UniMAP), 2023-01)
    N. H. Jakfar
    ;
    Khor Shing Fhan
    ;
    Banjuraizah Johar
    ;
    Nur Maizatul Shima Adzali
    ;
    S. N. H. Mohd. Yunus
    ;
    Cheng Ee Meng
    ;
    E. Z. M. Tarmizi
    ;
    Z. A. Talib
    This study was conducted to synthesise calcium monosilicate ceramics using rice husks and raw eggshells and investigated the effect of sintering temperature on the physical, microstructure and electrical properties of the final product. The high content of calcium and silicon in eggshells and rice husks, respectively promote the use of waste materials in the production of calcium monosilicates by mixing in a molar ratio 1CaO:1SiO2 and fired at different sintering temperatures for 2 hours with a heating rate of 10°C/min. A good correlation between sintering temperature, structural, microstructure, and electrical properties of calcium silicate was observed. The structural and morphological evolutions were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with electron dispersive X-ray analysis (EDX). XRD analysis showed that the main crystalline phases of synthesised calcium monosilicate are pseudowollastonite (ICSD 98- 005-2598) at 1250°C, and the phases of SiO2 also exist in different types of minerals. Besides, a small amount of larnite, Ca2SiO4 was traced at 1100°C and 1200°C. Fourier Transforms Infrared (FTIR) spectra showed the presence of characteristic functional groups in the precursor powder. In Nyquist plots, the summit frequency of the dominant arc decreases with increasing sintering temperatures. It may be attributed to the co-effect of the grain size and pore. A larger value of impedance at a lower frequency suggests an essential role of boundaries in governing the electrical properties of the sintered ceramics. As the sintering temperature increases, the microstructure of the sintered samples becomes denser while conductivity performance decreases. This is due to the reduction of particle interfaces and charge transfer.
      1  17
  • Publication
    Regression analysis of the dielectric and morphological properties for porous Nanohydroxyapatite/Starch composites: a correlative study
    ( 2022)
    Chong You Beh
    ;
    Cheng Ee Meng
    ;
    Nashrul Fazli Mohd Nasir
    ;
    Mohd Shukry Abdul Majid
    ;
    Khor Shing Fhan
    ;
    Mohd Ridzuan Mohd Jamir
    ;
    Emma Ziezie Mohd Tarmizi
    ;
    Kim Yee Lee
    This paper aims to investigate the dielectric properties, i.e., dielectric constant (ε′), dielectric loss factor (ε″), dielectric tangent loss (tan δ), electrical conductivity (σ), and penetration depth (Dp), of the porous nanohydroxyapatite/starch composites in the function of starch proportion, pore size, and porosity over a broad band frequency range of 5 MHz–12 GHz. The porous nanohydroxyapatite/starch composites were fabricated using different starch proportions ranging from 30 to 90 wt%. The results reveal that the dielectric properties and the microstructural features of the porous nanohydroxyapatite/starch composites can be enhanced by the increment in the starch proportion. Nevertheless, the composite with 80 wt% of starch proportion exhibit low dielectric properties (ε′, ε″, tan δ, and σ) and a high penetration depth because of its highly interconnected porous microstructures. The dielectric properties of the porous nanohydroxyapatite/starch composites are highly dependent on starch proportion, average pore size, and porosity. The regression models are developed to express the dielectric properties of the porous nanohydroxyapatite/starch composites (R2 > 0.96) in the function of starch proportion, pore size, and porosity from 1 to 11 GHz. This dielectric study can facilitate the assessment of bone scaffold design in bone tissue engineering applications.
      1  18
  • Publication
    Nonlinear optical characterization of phosphate glasses based on ZnO using the Z-scan technique
    ( 2013-06-07)
    Masoumeh Shokati Mojdehi
    ;
    Wan Mahmood Mat Yunus
    ;
    Khor Shing Fhan
    ;
    Zainal Abidin Talib
    ;
    N. Tamchek
    The nonlinear optical properties of a phosphate vitreous system [(ZnO)x −(MgO)30−x −(P2O5)70], where x = 8, 10, 15, 18, and 20 mol% synthesized through the melt-quenching technique have been investigated by using the Z-scan technique. In the experiment, a continuous-wave laser with a wavelength of 405 nm was utilized to determine the sign and value of the nonlinear refractive (NLR) index and the absorption coefficient with closed and opened apertures of the Z-scan setup. The NLR index was found to increase with the ZnO concentration in the glass samples by an order of 10−10 cm2 ·W−1. The real and imaginary parts of the third-order nonlinear susceptibility were calculated by referring tothe NLR index (n2) and absorption coefficient (β) of the samples. The value of the third-order nonlinear susceptibility was presented by nonlinear refractive or absorptive behavior of phosphate glasses for proper utilization in nonlinear optical devices. Based on the measurement, the positive sign of the NLR index shows a self-focusing phenomenon. The figures of merit for each sample were calculated to judge the potential of phosphate glasses for application in optical switching.
      27  2
  • Publication
    Regression analysis of the dielectric and morphological properties for Porous Nanohydroxyapatite/Starch composites: a correlative study
    ( 2022)
    Chong You Beh
    ;
    Cheng Ee Meng
    ;
    Nashrul Fazli Mohd Nasir
    ;
    Mohd Shukry Abdul Majid
    ;
    Khor Shing Fhan
    ;
    Mohd Ridzuan Mohd Jamir
    ;
    Emma Ziezie Mohd Tarmizi
    ;
    Kim Yee Lee
    This paper aims to investigate the dielectric properties, i.e., dielectric constant (ε′), dielectric loss factor (ε″), dielectric tangent loss (tan δ), electrical conductivity (σ), and penetration depth (Dp), of the porous nanohydroxyapatite/starch composites in the function of starch proportion, pore size, and porosity over a broad band frequency range of 5 MHz–12 GHz. The porous nanohydroxyapatite/starch composites were fabricated using different starch proportions ranging from 30 to 90 wt%. The results reveal that the dielectric properties and the microstructural features of the porous nanohydroxyapatite/starch composites can be enhanced by the increment in the starch proportion. Nevertheless, the composite with 80 wt% of starch proportion exhibit low dielectric properties (ε′, ε″, tan δ, and σ) and a high penetration depth because of its highly interconnected porous microstructures. The dielectric properties of the porous nanohydroxyapatite/starch composites are highly dependent on starch proportion, average pore size, and porosity. The regression models are developed to express the dielectric properties of the porous nanohydroxyapatite/starch composites (R2 > 0.96) in the function of starch proportion, pore size, and porosity from 1 to 11 GHz. This dielectric study can facilitate the assessment of bone scaffold design in bone tissue engineering applications.
      2  20
  • Publication
    Dielectric and biodegradation properties of biodegradable nano-hydroxyapatite/starch bone scaffold
    ( 2022)
    Beh Chong You
    ;
    Cheng Ee Meng
    ;
    Nashrul Fazli Mohd Nasir
    ;
    Emma Ziezie Mohd Tarmizi
    ;
    Khor Shing Fhan
    ;
    Eng Swee Kheng
    ;
    Mohd Shukry Abdul Majid
    ;
    Mohd Ridzuan Mohd Jamir
    This study is aim to investigate the dielectric properties (dielectric constant, ε′ and loss factor, ε′′) and the biodegradation properties of the nano-hydroxyapatite/starch bone scaffold with various starch proportion in simulated body fluid. The nano-hydroxyapatite/starch bone scaffolds with starch proportions 30, 40, 50, 60, 70, 80, and 90 wt.% were fabricated. The ε′ and ε′′ of nano-hydroxyapatite/starch composite decrease when frequency increases. However, it increases when starch proportion and temperature increase. The biodegradation properties of the nano-hydroxyapatite/starch bone scaffold can be improved when the dielectric properties and porosity are enhanced. The enhancement of dielectric properties and porosity is due to the increment of starch proportion. The nano-hydroxyapatite/starch bone scaffold with the high starch proportion exhibits nano-hydroxyapatite/starch interfaces with strong intermolecular interactions that can stabilize biodegradation and biomineralization. The dielectric properties of the simulated body solutions are highly sensitive to the variation of the ion concentrations (calcium and phosphate). The nano-hydroxyapatite/starch bone scaffold with 80 wt.% starch proportion exhibits significant dielectric and biodegradation properties. It has potential to be a biodegradable inorganic/organic bone scaffold.
      1  8
  • Publication
    Dielectric properties of hydrothermally modified potato, corn, and rice starch
    ( 2022)
    Chong You Beh
    ;
    Cheng Ee Meng
    ;
    Nashrul Fazli Mohd Nasir
    ;
    Mohd Shukry Abdul Majid
    ;
    Khor Shing Fhan
    ;
    Mohd Ridzuan Mohd Jamir
    ;
    Emma Ziezie Mohd Tarmizi
    ;
    Kim Yee Lee
    The effect of starch granule sizes, shapes, composition, and frequency on the dielectric properties (dielectric constant, loss factor, and conductivity) of native and hydrothermally modified starches (potato, corn, and rice starch) are investigated in this work. Dielectric properties are determined from 5 Hz to 5 GHz. The modified starches exhibit lower dielectric properties than the native starches from 5 Hz to 5 GHz due to the disruption of the native polysaccharide’s molecular arrangement. The modified potato starch shows the highest loss factor (208.12 at 50 Hz and 19.95 at 500 Hz) and stable conductivity (~5.33 × 10−7 S/m at 50 Hz and 500 Hz) due to the larger continuous network structure after hydrothermal modification. The rice starch shows the largest difference in dielectric constant (47.30%) and loss factor (71.42%) between the modified form and native form in the frequency range of 5 MHz–5 GHz. This is due to the restriction of dipole motions in the closely packed structure after hydrothermal modification. The findings indicate that the quality of starch modification can be characterized by dielectric properties for assisting starch-based plastic production’s design.
      2  15