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

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Study of thermoelectric properties of Sr₀.₉₂A₀.₀₈TiO₃ (A=Yb / Tm) perovskite oxide using density functional theory method

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.

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Thermoelectric properties of Sm doped CaMnO₃ using density functional theory method

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.

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Revisiting the optoelectronic properties of graphene : a DFT approach

2024-01 , L.O Agbolade , Alaa Kamal Yousif Dafhalla , A.Wesam Al-Mufti , Zainal Abidin Arsat , Tijjani Adam , Abdullah Chik , Subash Chandra Bose Gopinath , Muhammad Nur Aiman Uda , Uda Hashim

Understanding the atomic behaviour of pure graphene is crucial in manipulating its properties for achieving optoelectronics with high absorption indexes and efficiencies. However, previous research employing the DFT approach emphasised its zero-band gap nature, not its unique optical properties. Therefore, this study employed ab initio calculations to revisit the electronic, magnetic, and optical properties of pristine graphene using the WIEN2K code. The results reveal that the PBE-GGA valence and conduction bands cross at -0.7 eV. Our calculations demonstrated that the absorption coefficient of graphene has the strongest light penetration in the parallel direction. Furthermore, our results not only present the best possible propagation of light in pure graphene but also reveal that the linear relationship between the formation of the free electron carriers and the energy absorption is responsible for the high optical conductivity observed in pure graphene, as indicated by the peaks. Lastly, the metallic properties of graphene are reflected by the variation in spin up and down that appears, as evidenced by the total and partial densities of states, and the large refractive index attributed to its high electron mobility confirms its metallic nature.

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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.

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Effect of sintering temperature on the preparation and characterization of green glass ceramic from rice husk ash as a matrix

2020 , Shahrizam Saad , Abdullah Chik , Khairel Rafezi Ahmad , Sharifah Shahnaz Syed Bakar

Powder metallurgy technique were proved successful net-shape technology which suitable for the production of green glass ceramic (GGC) from rice husk ash (RHA) and characterized by good physical and mechanical properties of glass ceramic. In this research, the glass sample was formed by mixing varying percentage of weight of silica, flux and additives. The aim of this work is to study the effect of the sintering temperature to the physical and mechanical properties of GGC. The samples were mixed in different volume fraction of additives which is 5%, 10% and 15% in constant composition of RHA and flux. The mixture was consolidated into rigid die compaction at 300MPa, then sintered at 450, 550 and 750°C. Vickers hardness test were investigated. The glass composite were then characterize by scanning electron microscopy (SEM). The GGC with 10% additives at sintering temperature 550°C shows highest hardness strength which is about 213.0 HV.

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First Principles Enhanced Electronic Band Structure of SrTiO₃ using DFT+U Method

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.

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Recent advances in density functional theory approach for optoelectronics properties of graphene

2023-03-01 , Olatomiwa A.L. , Tijjani Adam , Edet C.O. , Adewale A.A. , Abdullah Chik , Mohammed M. , Subash Chandra Bose Gopinath , Uda Hashim

Graphene has received tremendous attention among diverse 2D materials because of its remarkable properties. Its emergence over the last two decades gave a new and distinct dynamic to the study of materials, with several research projects focusing on exploiting its intrinsic properties for optoelectronic devices. This review provides a comprehensive overview of several published articles based on density functional theory and recently introduced machine learning approaches applied to study the electronic and optical properties of graphene. A comprehensive catalogue of the bond lengths, band gaps, and formation energies of various doped graphene systems that determine thermodynamic stability was reported in the literature. In these studies, the peculiarity of the obtained results reported is consequent on the nature and type of the dopants, the choice of the XC functionals, the basis set, and the wrong input parameters. The different density functional theory models, as well as the strengths and uncertainties of the ML potentials employed in the machine learning approach to enhance the prediction models for graphene, were elucidated. Lastly, the thermal properties, modelling of graphene heterostructures, the superconducting behaviour of graphene, and optimization of the DFT models are grey areas that future studies should explore in enhancing its unique potential. Therefore, the identified future trends and knowledge gaps have a prospect in both academia and industry to design future and reliable optoelectronic devices.

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Electronic properties of calcium and zirconium co-doped BaTiO₃

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.

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Pengenalan kepada Pemprosesan Fizikal Mineral

2013 , Shahrizam Saad , Faizul Che Pa , Abdullah Chik , Mohamed Faisal, Mohamed Noor

Umum mengetahui kepentingan mineral dan logam dalam kehidupan manusia seharian. Walau bagaimanapun, tidak ramai yang mempunyai pemahaman jelas berkaitan dengan pemprosesan peringkat awal bahan ini. Situasi ini mengilhamkan para penulis buku ini untuk menghasilkan buku Pengenalan Kepada Pemprosesan Fizikal Mineral. Objektif utama penulisan buku ini adalah untuk memperbanyakkan bahan rujukan berkaitan pemprosesan mineral dalam medium Bahasa Melayu bagi kegunaan para pelajar dan masyarakat secara amnya. Pemprosesan mineral adalah satu kaedah yang digunakan untuk pengekstrakan bijih bagi mendapatkan mineral atau logam berharga yang dikenali sebagai konsentrat. Bermula daripada aktiviti perlombongan, bijih yang dilombong seterusnya akan menjalani beberapa peringkat proses untuk memisahkan konsentrat daripada mineral reja. Antara proses-proses yang terlibat adalah proses pengurangan saiz atau kominusi yang melibatkan proses penghancuran dan pengisaran. Proses penyaringan dan pengelasan pula bertujuan untuk mendapatkan taburan saiz yang dikehendaki untuk proses-proses seterusnya. Proses pemisahan konsentrat pula bergantung kepada ciri-ciri fizikal mineral seperti garviti tentu, kekonduksian dan magnetik manakala pemisahan yang bergantung kepada ciri-ciri kimia permukaan mineral pula adalah melibatkan proses pengapungan. Konsentrat yang terhasil daripada proses yang melibatkan pemisahan menggunakan medium air seterusnya akan menjalani proses penyahairan bagi menyingkirkan kandungan kelembapan konsentrat sebelum dihantar kepada pelebur untuk tujuan peleburan.

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Structural, electronic and thermoelectric properties of SrTiO₃ ceramic doped by lanthanum using first principles

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.

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