Ahmad Azmin Mohamad | Universiti Sains Malaysia (original) (raw)
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Papers by Ahmad Azmin Mohamad
Materials Research Express, 2020
This work aims to provide deep morphological observation on the incorporated TiO2 nanoparticles w... more This work aims to provide deep morphological observation on the incorporated TiO2 nanoparticles
within the SAC305 by selective electrochemical etching. Cyclic voltammetry and chronoamperometry
were used to investigate the selective etching performances. The removal of β-Sn matrix was
conducted at a fixed potential of−350 mV. Average performances of 2.19 and 2.30 mAwere attained
from the chronoamperometry. The efficiency of β-Sn removal was approved according to the
reduction of the intensities on the phase analysis. Successful observation of the TiO2 near the Cu6Sn5
layer was attained for an optimum duration of 120 s. Clusters of TiO2 nanoparticles were entrapped by
Cu6Sn5 and Ag3Sn intermetallic compound (IMC) layer network and at the solder/substrate interface.
The presence of TiO2 nanoparticles at the solder interface suppresses the growth of the Cu6Sn5 IMC
layer. The absence of a β-Sn matrix also allowed in-depth morphological observations to be made of
the shape and size of the Cu6Sn5 and Ag3Sn. It was found that TiO2 content facilitates the β-Sn
removal, which allows better observation of the IMC phases as well as the TiO2 reinforcement
particles.
Materials Research Express, 2020
This work aims to provide deep morphological observation on the incorporated TiO 2 nanoparticles ... more This work aims to provide deep morphological observation on the incorporated TiO 2 nanoparticles within the SAC305 by selective electrochemical etching. Cyclic voltammetry and chronoamperometry were used to investigate the selective etching performances. The removal of β-Sn matrix was conducted at a fixed potential of −350 mV. Average performances of 2.19 and 2.30 mA were attained from the chronoamperometry. The efficiency of β-Sn removal was approved according to the reduction of the intensities on the phase analysis. Successful observation of the TiO 2 near the Cu 6 Sn 5 layer was attained for an optimum duration of 120 s. Clusters of TiO 2 nanoparticles were entrapped by Cu 6 Sn 5 and Ag 3 Sn intermetallic compound (IMC) layer network and at the solder/substrate interface. The presence of TiO 2 nanoparticles at the solder interface suppresses the growth of the Cu 6 Sn 5 IMC layer. The absence of a β-Sn matrix also allowed in-depth morphological observations to be made of the shape and size of the Cu 6 Sn 5 and Ag 3 Sn. It was found that TiO 2 content facilitates the β-Sn removal, which allows better observation of the IMC phases as well as the TiO 2 reinforcement particles.
This review aims to briefly outline the Hubbard-U scheme and to investigate the effect of its inc... more This review aims to briefly outline the Hubbard-U scheme and to investigate the effect of its inclusion in standard Density Functional Theory on electronic, structural, and optical properties of ZnO wurtzite structure. To remedy the miscalculation of optimized lattice parameters determined by Local Density Approximation and Generalized Gradient Approximation approximations to experimental values, the effect of the implementation of Hubbard-U correction for only d state or for both d and p states was investigated for theoretical data collected from previous works. Further effort was devoted to studying the incorporation of U d,Zn and U p,O to reproduce correct band gap, to exploring various regions composed of valence and conduction bands and their origin, and to revealing the nature of chemical bonding. This review also provides graphical and tabulated values extracted from earlier works on optical properties of ZnO wurtzite structure. It summarizes the effect of U d,Zn and U p,O in several exchange-correlation functionals on the intensity and location of major peaks composed real and imaginary part of dielectric function as well as on the shift of main absorption peak and optical absorption edge. A comparison was made, wherever possible, between theoretical and experimental results.
The application of quasi-solid state electrolytes for dye-sensitized solar cells opens up an inte... more The application of quasi-solid state electrolytes for dye-sensitized solar cells opens up an interesting research field to explore, which is evident from the increasing amount of publications on this topic. Since 2010, significant progress has been made with new and more complicated quasi-solid-states materials being produced. The optimization of new materials requires specific characterizations. This review presents a comprehensive overview and recent progress of characterization methods for studying quasi- solid-state electrolytes. Emphasis is then placed on the absorbency and conductivity characterizations. Each characterization will be reviewed according to the objective, experimental set-up, summary of important outcomes, and a few case studies worth discussing. Finally, strategies for future characterizations and developments are described.
The electrolyte is a critical component of dye-sensitised solar cells (DSSCs). Among them, quasi-... more The electrolyte is a critical component of dye-sensitised solar cells (DSSCs). Among them, quasi-solid state (QSS) electrolytes are considered as one of the most prospective substitutes for liquid electrolytes to DSSCs. To entirely understand and optimise the performance and stability of QSS, comprehensive characterisation is needed to design new materials, comprehend and optimise the QSS. This review summarises the characterisations of QSS beginning from 2010. Emphasis is placed on the physical characterisations such as viscosity, morphology, thermal, infrared spectroscopy, nuclear magnetic resonance, Raman, ultraviolet-visible, and X-ray diffraction. All parts of the characterisation process are divided into the introduction, the objective of testing, main outcomes and finally, the selected examples. A summary of recent and important measurements on QSS are mentioned at the end.
Materials Research Express, 2020
This work aims to provide deep morphological observation on the incorporated TiO2 nanoparticles w... more This work aims to provide deep morphological observation on the incorporated TiO2 nanoparticles
within the SAC305 by selective electrochemical etching. Cyclic voltammetry and chronoamperometry
were used to investigate the selective etching performances. The removal of β-Sn matrix was
conducted at a fixed potential of−350 mV. Average performances of 2.19 and 2.30 mAwere attained
from the chronoamperometry. The efficiency of β-Sn removal was approved according to the
reduction of the intensities on the phase analysis. Successful observation of the TiO2 near the Cu6Sn5
layer was attained for an optimum duration of 120 s. Clusters of TiO2 nanoparticles were entrapped by
Cu6Sn5 and Ag3Sn intermetallic compound (IMC) layer network and at the solder/substrate interface.
The presence of TiO2 nanoparticles at the solder interface suppresses the growth of the Cu6Sn5 IMC
layer. The absence of a β-Sn matrix also allowed in-depth morphological observations to be made of
the shape and size of the Cu6Sn5 and Ag3Sn. It was found that TiO2 content facilitates the β-Sn
removal, which allows better observation of the IMC phases as well as the TiO2 reinforcement
particles.
Materials Research Express, 2020
This work aims to provide deep morphological observation on the incorporated TiO 2 nanoparticles ... more This work aims to provide deep morphological observation on the incorporated TiO 2 nanoparticles within the SAC305 by selective electrochemical etching. Cyclic voltammetry and chronoamperometry were used to investigate the selective etching performances. The removal of β-Sn matrix was conducted at a fixed potential of −350 mV. Average performances of 2.19 and 2.30 mA were attained from the chronoamperometry. The efficiency of β-Sn removal was approved according to the reduction of the intensities on the phase analysis. Successful observation of the TiO 2 near the Cu 6 Sn 5 layer was attained for an optimum duration of 120 s. Clusters of TiO 2 nanoparticles were entrapped by Cu 6 Sn 5 and Ag 3 Sn intermetallic compound (IMC) layer network and at the solder/substrate interface. The presence of TiO 2 nanoparticles at the solder interface suppresses the growth of the Cu 6 Sn 5 IMC layer. The absence of a β-Sn matrix also allowed in-depth morphological observations to be made of the shape and size of the Cu 6 Sn 5 and Ag 3 Sn. It was found that TiO 2 content facilitates the β-Sn removal, which allows better observation of the IMC phases as well as the TiO 2 reinforcement particles.
This review aims to briefly outline the Hubbard-U scheme and to investigate the effect of its inc... more This review aims to briefly outline the Hubbard-U scheme and to investigate the effect of its inclusion in standard Density Functional Theory on electronic, structural, and optical properties of ZnO wurtzite structure. To remedy the miscalculation of optimized lattice parameters determined by Local Density Approximation and Generalized Gradient Approximation approximations to experimental values, the effect of the implementation of Hubbard-U correction for only d state or for both d and p states was investigated for theoretical data collected from previous works. Further effort was devoted to studying the incorporation of U d,Zn and U p,O to reproduce correct band gap, to exploring various regions composed of valence and conduction bands and their origin, and to revealing the nature of chemical bonding. This review also provides graphical and tabulated values extracted from earlier works on optical properties of ZnO wurtzite structure. It summarizes the effect of U d,Zn and U p,O in several exchange-correlation functionals on the intensity and location of major peaks composed real and imaginary part of dielectric function as well as on the shift of main absorption peak and optical absorption edge. A comparison was made, wherever possible, between theoretical and experimental results.
The application of quasi-solid state electrolytes for dye-sensitized solar cells opens up an inte... more The application of quasi-solid state electrolytes for dye-sensitized solar cells opens up an interesting research field to explore, which is evident from the increasing amount of publications on this topic. Since 2010, significant progress has been made with new and more complicated quasi-solid-states materials being produced. The optimization of new materials requires specific characterizations. This review presents a comprehensive overview and recent progress of characterization methods for studying quasi- solid-state electrolytes. Emphasis is then placed on the absorbency and conductivity characterizations. Each characterization will be reviewed according to the objective, experimental set-up, summary of important outcomes, and a few case studies worth discussing. Finally, strategies for future characterizations and developments are described.
The electrolyte is a critical component of dye-sensitised solar cells (DSSCs). Among them, quasi-... more The electrolyte is a critical component of dye-sensitised solar cells (DSSCs). Among them, quasi-solid state (QSS) electrolytes are considered as one of the most prospective substitutes for liquid electrolytes to DSSCs. To entirely understand and optimise the performance and stability of QSS, comprehensive characterisation is needed to design new materials, comprehend and optimise the QSS. This review summarises the characterisations of QSS beginning from 2010. Emphasis is placed on the physical characterisations such as viscosity, morphology, thermal, infrared spectroscopy, nuclear magnetic resonance, Raman, ultraviolet-visible, and X-ray diffraction. All parts of the characterisation process are divided into the introduction, the objective of testing, main outcomes and finally, the selected examples. A summary of recent and important measurements on QSS are mentioned at the end.