Prabakaran A/L Poopalan
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Prabakaran A/L Poopalan
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Prabakaran, A/L Poopalan
Alternative Name
Poopalan, P.
Poopalan, Prabakaran A.L.
Poopalan, Prabakaran
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Scopus Author ID
7003686974

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  • Publication
    Eu3+ activated non-crystalline BaTiO3 ultra-thin film phosphor with high purity, tailored red emission from n-UV excitation for WLEDs applications
    ( 2023-12-15)
    Lee K.T.
    ;
    Prabakaran A/L Poopalan
    As an alternative WLED red phosphor, BaTiO3 sol-gel based ultra-thin films were doped with various mol% of Eu3+ and annealed at 500 °C. The films were amorphous with short range ordered structure as seen via XRD and Raman analysis. Photoluminescence (PL) emission spectra enabled the determination of Eu3+ location asymmetry in the host via Judd-Ofelt (J-O) theory, from which Ω2=9.37×10−20cm2 and Ω4=1.55×10−20cm2 were derived, proving that the Eu3+ ions were non-centrosymmetrically located. This enhanced the Eu3+ 5D0 → 7F2 electric-dipole transition at 614.0 nm with the strongest emission from 30 mol% doping. 395 nm excited intense and narrow red spectral profiles which exhibited excellent colour coordinates (x = 0.657, y = 0.342), quantum efficiency (25.7% at a film thickness of ∼380 nm), and colour purity of (92.0%) whereby the red to orange ratio (R: O) enables colour tailoring with 5 mol% to 30 mol% Eu3+doping. This facilitates flexible control over the colour output, ensuring that it can be easily tailored to meet specific application requirements. The aforementioned results indicate that the red-emitting Eu3+ activated amorphous BaTiO3 ultra-thin film phosphors exhibit promising potential for application in n-UV excited WLEDs as a red phosphor with a branching ratio β0→2=81.43% making it a potential candidate for red laser materials too.
      1  12
  • Publication
    Ga 2 O 3 thin films by sol-gel method its optical properties
    ( 2020-01-08)
    Cheah L.
    ;
    Rozana Aina Maulat Osman
    ;
    Prabakaran A/L Poopalan
    Gallium (III) oxide Ga2O3 is emerging in the field of wide bandgap semiconductor for various applications such as solar-blind photodetectors et al. because of its wide bandgap. For this reason, the optical properties of Ga2O3 by sol-gel method are analyzed. Ga2O3 thin films are prepared by spin coating method. The annealing temperature to make α-Ga2O3 is in the range of 450°C-550°C, where after 550°C, β-Ga2O3 is obtained as reported in reviewed works. Therefore, annealing temperatures of samples are set at 500°C, 700°C and 900°C. X-ray diffraction is performed to characterize the structure of the sample. The optical bandgap of Ga2O3 is calculated based on the transmittance value measured from UV-Visible spectrophotometer, which range from 4.8eV to 5.0eV.
      2  22
  • Publication
    Effect of Sn Doping on the Curie Temperature, Structural, Dielectric and Piezoelectric Properties of Ba0.8Sr0.2Ti1−xSnxO3 Ceramics
    ( 2023-11-01)
    Nasir N.N.
    ;
    Rozana Aina Maulat Osman
    ;
    Mohd Sobri Idris
    ;
    Muhsen K.N.D.K.
    ;
    Prabakaran A/L Poopalan
    ;
    Nur Izzati Muhammad Nadzri
    ;
    Jumali M.H.H.
    ;
    Jamil N.H.B.
    Ba0.8Sr0.2Ti1−xSnxO3 material with varying Sn concentrations (x = 0, 0.02, 0.04, 0.06, 0.08, and 0.10) was synthesized using the conventional solid-state reaction method. X-ray diffraction (XRD) analysis reveals that as the Sn concentration increases from x = 0 to x = 0.10, the Ba0.8Sr0.2Ti1−xSnxO3 undergoes a structural phase change from tetragonal to cubic. Dielectric analysis of Ba0.8Sr0.2Ti1−xSnxO3 shows a significant drop in Tc, from 65 to 5°C, caused by the replacement of Sn4+ ions with larger ionic radii compared to Ti4+ ions at the B-sites. The composition with x = 0 exhibits the largest dielectric constant due to its enormous spontaneous dipole moments. Conversely, the substitution of Sn in Ba0.8Sr0.2Ti1−xSnxO3 reveals a decrease in the dielectric constant at the B-site structure of perovskite, resulting in a reduced tolerance factor and a decrease in the tetragonality of the sample. However, the pinching effect significantly enhances the dielectric constant of the sample with x = 0.10. Grain size measurements for x = 0 demonstrate a well-distributed grain structure. Additionally, the undoped sample exhibits a higher piezoelectric constant than the Ba0.8Sr0.2Ti1−xSnxO3 samples. According to the piezoelectric constant data, the composition with a tetragonal structure appears to have a greater piezoelectric constant than the cubic structure.
      1  39
  • Publication
    Automatic energy monitoring system
    ( 2020-01-08)
    Jawaduddin A.
    ;
    Airij A.
    ;
    Prabakaran A/L Poopalan
    The energy monitoring system is a system that measures utilization of power in normal interims and allows that data to be accessible to its partners by a system interface. The energy monitoring system allows the likelihood to give prompt feedback on an individual's power utilization which saves the work of reading the values from the meter, supports the introduction of time-based energy tariffs, increases the grid state awareness, and conceivably supports a fast access for turning the power flow on/off. The present energy monitoring systems have several problems just like problem of payment collection, energy thefts, quality of photographs that is printed on bill etc. because of which the current billing system is not reliable, expensive, and slower. The traditional billing system has odds of mistakes and it also takes a lot of time. To overcome these problems, the system consists of a current sensor, Atmega328 microcontroller, LCD module and a status LED. The entire system runs on a 9V battery supply. The nature of the sensor's output is analog which is then transformed into digital with the aid of pre-built analog to digital convertor in the microcontroller. The output of the entire system is displayed on the LCD display which is connected to the microcontroller. In order to measure the current of the desired device, the device is plugged in the extension that is connected with the sensor. The conclusion is drawn that the developed energy monitoring system in this research is capable of measuring current of appliances with the efficiency of 99% with the help of ACS712 hall-effect current sensor.
      2  14
  • Publication
    UV Modified Epoxy for LED Encapsulant
    ( 2020-06-16)
    Cheah L.B.
    ;
    Heng C.W.
    ;
    Ng S.Y.
    ;
    Teh Pei Leng
    ;
    Prabakaran A/L Poopalan
    Light Emitting Diode (LED) packaging is important for the protection and enhancement of light extraction efficiency in LED. The most commonly used encapsulant is epoxy resin, which is the annealing cured. Multilayer time delayed aging of the epoxy resin causes delamination during packaging process. Ultraviolet (UV) modification is introduced in the curing process of epoxy resin to enhance the curing process of the epoxy. In this paper, the samples tested are either modified with UV or vice versa. Differential Scanning Calorimeter (DSC) is used for the analysis of the sample. Six samples are tested. Data analysis is based on the heat of reactions between the mixed materials; either the process is exothermic or endothermic when the temperature changes. The reaction between the materials determines its ability to crosslink, viscosity and temperature control for the whole reaction.
      1  15