Abdullah Chik
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Preferred name
Abdullah Chik
Official Name
Abdullah, Chik
Alternative Name
Chik, Abdullah
Chik, A
Chik, Abdullah bin
Main Affiliation
Scopus Author ID
15768692100
Researcher ID
EPX-6197-2022

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  • Publication
    Study of thermoelectric properties of Sr₀.₉₂A₀.₀₈TiO₃ (A=Yb / Tm) perovskite oxide using density functional theory method
    (IOP Publishing, 2020)
    Akeem Adekunle Adewale
    ;
    Abdullah Chik
    ;
    Ruhiyuddin Mohd Zaki
    The first principle methods have been employed to investigate electronic and thermoelectric properties of Sr₀.₉₂Yb₀.₀₈TiO₃ and Sr₀.₉₂Tm₀.₀₈TiO₃ perovskite-oxide based molded samples. Generalized gradient approximation (GGA) with Hubbard U parameter is used by WIEN2k code for the calculations. The straight band line was observed in the band structure of both studied samples. This was generated from 4f-orbitals as shown in partial density of state diagrams. It is also noticed that Yb and Tm doped in SrTiO₃ changed the perovskite-based oxide from a wideband insulator to metallic nature. A thermoelectric power factor of Sr₀.₉₂Tm₀.₀₈TiO₃ sample is higher than that of Sr₀.₉₂Yb₀.₀₈TiO₃, this is as a result of its huge electrical conductivity. The dependent of chemical potential to temperature was revealed in the study where high value of power factor was recorded for high temperature.
  • Publication
    Electronic properties of calcium and zirconium co-doped BaTiO₃
    (Trans Tech Publications Ltd., 2020)
    Akeem Adekunle Adewale
    ;
    Abdullah Chik
    ;
    Ruhiyuddin Mohd Zaki
    Barium titanate (BaTiO₃) is a perovskite based oxides with many potential application in electronic devices. From experimental report BaTiO₃ has wide energy band gap of about 3.4 eV which by doped with Ca and Zr at A-and B-sites respectively can enhance their piezoelectric properties. Using first principles method within the density functional theory (DFT) as implement in Quantum Espresso (QE) with the plane wave pseudo potential function, the influence of the Ca and Zr doping in BaTiO₃ are studied via electronic properties: band structure, total density of states (TDOS) and partial density of states (PDOS). The energy band gap calculated was underestimation which is similar to other DFT work. Two direct band gap where observed in Ba₀.₈₇₅Ca₀.₁₂₅Ti₀.₈₇₅Zr₀.₁₂₅O₃ sample at Γ-Γ (2.31 eV) and X-X (2.35 eV) symmetry point.
  • Publication
    Thermoelectric properties of Sm doped CaMnO₃ using density functional theory method
    (Trans Tech Publications Ltd., 2020-09)
    Abdullah Chik
    ;
    Ruhiyuddin Mohd Zaki
    ;
    Akeem Adekunle Adewale
    ;
    Faizul Che Pa
    ;
    Yeoh Cheow Keat
    The electronic structure and thermoelectric properties of CaMnO₃ doped with 8% and 17% f block element Sm using first principles calculations and semi-classic Boltzmann theory were presented in this paper. The G-type AFM phase is most stable among five phases for CaMnO3, however, with 8% and 17% Sm doping, these compounds became nonmagnetic phases. CaMnO₃ calculated electronic band structure shows an indirect band gap of 0.523 eV, which is underestimated by the density functional theory (DFT) calculations but the band gap explains the semiconducting behavior. However, with 8% and 17% Sm doping, the electronic bandstructure of these compounds exhibit metallic behavior, with Sm 4f and Mn 3d electrons contributing to conduction band, increasing the magnitude of conductivity for doped compounds. All temperature dependence Seebeck coefficient plots show n-typed conduction for all compound with reduced magnitude of Seebeck coefficient for doped compounds. The temperature dependence thermal conductivity plot shows overall thermal conductivity is reduced in Sm doped compound. CaMnO₃ with 17% Sm doping exhibit much higher ZT of 0.32 at 800 K showing enhanced thermoelectric properties at high temperature and suitability or high temperature energy conversion devices.
  • Publication
    First Principles Enhanced Electronic Band Structure of SrTiO₃ using DFT+U Method
    (Universiti Malaysia Perlis (UniMAP), 2019-01)
    Akeem Adekunle Adewale
    ;
    Abdullah Chik
    Density functional theory (DFT) technique was used to study the influence of Hubbard U on the calculated electronic properties of perovskite SrTiO₃. We used the Quantum Espresso (QE) software package with exchange-correction energy function within local density approximation for DFT and DFT+U calculations. The band structure, total and partial density of states (DOS and PDOS) were calculated. Three set of methods were adopted in the calculations: DFT without U, DFT+U with calculated U through linear response theory, and DFT+U with manually increment of U value. The calculated Hubbard U using linear response theory is 3.27 while selected U for manual increment method were chosen from 4.27 to 10.27 with an interval of 1. For DFT and DFT+U with calculated U, the calculated band gaps were 1.80 and 2.19 eV respectively. During increasing of U the calculated band gap were increasing from 2.43 eV (@U=4.27) and reaches peak of 3.06 eV (@U=8.27) which later reduce to 2.19 eV (@U=10.27). Therefore, DFT+U method with incremental Hubbard U resulted in better band gap value of 3.06 eV that is closer to the experimental result of 3.25 eV.
  • Publication
    Structural, electronic and thermoelectric properties of SrTiO₃ ceramic doped by lanthanum using first principles
    (IOP Publishing Ltd., 2020)
    Akeem Adekunle Adewale
    ;
    Abdullah Chik
    ;
    Ruhiyuddin Mohd Zaki
    The Sr₀.9₂La₀.₀₈TiO₃ model compound was studied by means of the first-principles method grounded on the full-potential linearized augmented plane wave with the local orbital method as implement in WIEN2k. The structures, electronic and thermoelectric properties of the model compound are examined. Geometry optimization of Sr₀.9₂La₀.₀₈TiO₃ compound structure reveals the lattice constant of 3.9451 Å, which is the same as un-doped SrTiO₃. The direct bandgap of 2.48 eV (Γ-Γ) was measured from computed electronic band structure and its displayed density of states for Sr₀.9₂La₀.₀₈TiO₃ sample. Transport properties were calculated using BoltzTraP code as implemented in the WIEN2k code. The results were analyzed as a function of the variable temperatures, the density of state and chemical potential. Temperature and density of state variation with transport properties are in the same trend. Chemical potential proves material as n-type via Seebeck coefficient. The thermoelectric performance ZT of 0.05 was obtained at room temperature, while maximum value of 3.79 was recorded at 1200 K.
      26  1
  • Publication
    Optoelectronic behavior of ZnS compound and its alloy: A first principle approach
    ( 2021-06-01)
    Akeem Adekunle Adewale
    ;
    Abdullah Chik
    ;
    Tijjani Adam
    ;
    Joshua Tolulope Majekodunmi
    ;
    Durowoju M.O.
    First principles calculations were employed to study the structural, electronic and optical properties of pristine ZnS and its alloy compounds; Zn0.75Cr0.25S, Zn0.75Ti0.25S & Zn0.50Cr0.25Ti0.25S. To investigate these, full potential linear augmented plane wave (FPLAPW) based on density functional theory (DFT) was adopted as implement in WIEN2K code by employing generalized gradient approximation (GGA) of the revised Perdew-Burke Erzenhoff (PBE) as exchange correlation function. Lattice constant, volume, bulk modulus and other physical parameters were calculated for structural properties. Variation in these parameters in crystal structure is related to difference in ionic radius of host and replaced atom. The results of band structure and density of states were determined for electronic properties. The pristine ZnS and Zn0.75Ti0.25S compounds are semiconductor in nature while Zn0.75Cr0.25S and Zn0.50Cr0.25Ti0.25S displayed metallic character. Optical parameters including absorption coefficient, energy loss function, complex refractive index; refractive index and extinction coefficient, and optical conductivity have been computed from the dielectric function at energy range of 0–25 eV. Static dielectric constant for ε1(ω) are found to be 6.61, 1811.89, 155.46 and 1446.14 in ZnS, Zn0.75Cr0.25S, Zn0.75Ti0.25S and Zn0.50Cr0.25Ti0.25S respectively. The mean peaks of absorption are found at energy range of ∼5–10.5 eV for all studied compounds. We obtained noble performance of optical conductivity of doped at 0–7 eV which is due to presence of 3d – orbitals in the doped compounds. Our results are compared with available theoretical calculations and the experimental data.
      4  1
  • Publication
    DFT Study of Thermoelectric Performance of SrTiO₃ Doped by Tantalum
    (Universiti Malaysia Perlis (UniMAP), 2019-10)
    Akeem Adekunle Adewale
    ;
    Abdullah Chik
    ;
    Ruhiyuddin Mohd Zaki
    ;
    Faizul Che Pa
    ;
    Yeoh Cheow Keat
    ;
    Noorina Hidayu Jamil
    This paper deals with enhancement of thermoelectric performance of SrTiO₃ - a perovskite-based material by doping Ti-site with Ta. The electronic and the thermoelectric transport properties of doped SrTiO₃ were studied using the first principle calculation in full-potential of density functional theory. Spin-orbit coupling including Hubbard U parameter influences were observed in the investigation. Energy band structure and electron density of state were determined for electronic properties. The Seebeck coefficients, thermal conductivity, electrical conductivity as well as thermoelectric efficiency ZT were calculated for thermoelectric properties. The results of our calculations revealed that narrowing the bandgap of the material leads to the increase of thermoelectric efficiency ZT. At spin-orbit coupling with DFT+U method, ZT of 0.18 at 750 K were obtained and this is similar to the experimental data reported.
      1
  • Publication
    The effect of Sn doping on the thermoelectric properties of SiGe using first principle technique
    (Trans Tech Publications Ltd., 2020)
    Abdullah Chik
    ;
    Haw Wei Kheng
    ;
    Ruhiyuddin Mohd Zaki
    ;
    Akeem Adekunle Adewale
    ;
    Faizul Che Pa
    ;
    Yeoh Cheow Keat
    The thermoelectric properties of hexagonal SiGe doped with Sn with doping percentage of 12.5% and 25% were investigated using linearised augmented plane wave method using the WIEN2k package and semiclassical Boltztmann Transport equation using the BoltzTraP software for the purpose of understanding the role of Sn as a dopant in the SiGe. For temperature range of 300 to 1000 K, it can be seen that by doping with Sn, there is an improvement in overall thermal conductivity of the samples with the highest improvement is in the 25% doped sample. The conductivity vs temperature for 25% Sn doped SiGe also shows higher value through temperature range from 300 K to 1000 K, however the Seebeck coefficient decreases with Sn doping percentage for the same temperature range. Due to lower Seebeck coefficient and higher thermal conductivity values, the overall thermoelectric coefficient, ZT, of the doped compound is lower than the SiGe values with highest ZT equal to 0.29 and 0.17 at 650 K for 12.5% and 25% respectively while the ZT of simulated SiGe at 650 K is 0.35. Thus 25% Sn doping actually reduce the ZT but enhanced the thermal and electrical conductivity of SiGe for temperature range of 300 to 1000 K.
      1  13