Mohd Sobri Idris
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Preferred name
Mohd Sobri Idris
Official Name
Mohd Sobri , Idris
Alternative Name
Idris, Mohd Sobri
Idris, M. Sobri
Idris, M. S.
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Scopus Author ID
55898869500
Researcher ID
G-2128-2010

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Electrical properties of Sn doped SrTiO₃

2020-01 , Muhammad Haniff Fisoldin , Mohd Sobri Idris , Rozana Aina Maulat Osman , Ku Noor Dhaniah Ku Muhsen , Zul Azhar Zahid Jamal

The crystal structure and electrical properties of SrTiO₃ with addition of 50 mol% SnO2 was studied. Samples were prepared using conventional solid-state reaction route. The results indicate that Sn doped SrTiO₃ was single phase with cubic phase and space group Pm-3m after final sintering temparture at 1400°C. Two semicircular arcs clearly observed in Z" versus Z' plots for SrTi0.5Sn0.5O3 semicircles associated with bulk relaxation processes and grain boundary effect. The heterogeneity of sample was observed form Z' and M" spectroscopic plot. The highest dielectric constant is observed at much higher temperature which nearly 2000 at low frequency measurement.

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Dielectric and structural analysis of hexagonal and tetragonal phase BaTiO3

2020-01-08 , Nurul Huda Yusoff , Rozana Aina Maulat Osman , Mohd Sobri Idris , Ku Noor Dhaniah Ku Muhsen , Nurul Izza Mohd Nor

Barium titanate (BaTiO3) has been synthesized using conventional solid state reaction method at sintering temperatures of 1150°C and 1400°C. A single phase tetragonal perovkite BaTiO3 was observed at 1150°C and changed to hexagonal phase at 1400a°C. The result was confimed by using X-ray diffraction analysis. Hexagonal BaTiO3 exhibits almost linear dielectric constant value between 60 to 120, however the tetragonal phase shows a phase transition from tetragonal to cubic at 120a°C. The tetragonal phase BaTiO3 has the highest dielectric constant 6000 at Tc and 4000 at room temperature.

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Colossal permittivity and dielectric behaviour of (Nb₀.₅Fe₀.₅)₀.₁Ti₀.₉O₂ and (Ta₀.₅Fe₀.₅)₀.₁Ti₀.₉O₂ ceramics

2023 , Ku Noor Dhaniah Ku Muhsen , Rozana Aina Maulat Osman , Mohd Sobri Idris

The influence of pentavalent elements (Nb⁵⁺, Ta⁵⁺) with Fe³⁺ on TiO₂ ceramic were investigated. The (Nb₀.₅Fe₀.₅)₀.₁Ti₀.₉O₂ and (Ta₀.₅Fe₀.₅)₀.₁Ti₀.₉O₂ ceramics have been synthesized and realized that the effect of Nb in the system has developed lattice expansion, although Nb and Ta exhibit similar ionic radii. The colossal permittivity value for (Nb₀.₅Fe₀.₅)₀.₁Ti₀.₉O₂ ceramic is about εr ≥ 104 which is slightly higher than the (Ta₀.₅Fe₀.₅)₀.₁Ti₀.₉O₂ ceramic. According to the dielectric analysis, both ceramics exhibit colossal permittivity below 10³ Hz which contributed by the electron-pinned defect-dipole (EPDD) model. However, the low εr values in the high-frequency region are associated with the internal barrier layer capacitor (IBLC) model. In addition, the grain boundary resistance is far greater than the grain resistivity (Rgb≫ Rg) which confirmed the existence of the IBLC effect by equivalent circuit analysis.

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Impedance and modulus spectroscopy of polycrystalline Ba0.9995La0.0005TiO3for multilayer ceramic capacitor

2021-07-21 , Tiong Yuan Tze , Rozana Aina Maulat Osman , Mohd Sobri Idris , Ku Noor Dhaniah Ku Muhsen , Nurul Izza Mohd Nor , Wahab Y.A. , Sagadevan S. , Sebastian T. , Arturo R.L.D.

Ba0.9995La0.0005TiO3 ceramics prepared via solid-state reaction route was found to be phase pure at the final sintering temperature of 1300°C for 16 hours. The dielectric constant was varied from 1900 to 2800 from 10 Hz to 100 kHz. Impedance spectroscopy is a powerful technique to study the complexities of ceramic materials such as homogeneity and inhomogeneity of materials that being process during production of most electronic materials. An electronic ceramic component can be visualized as a grain, grain boundary and electrode system. Impedance spectroscopy is being widely used to separate out contribution of the bulk and the grain boundary to the overall equivalent circuit models. Fixed frequency plots of dielectric constant versus temperature for Ba0.9995La0.0005TiO3 ceramics shows typical perovskite response with Curie temperature, Tc about 115 °C and fit with the equivalent circuit which contributed by bulk and grain boundary response.

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