KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/kmitl/1

Browse

Settings

Author: search.filters.author.Yotthuan, SuriratSubject: search.filters.subject.Rietveld refinement

Search Results

Now showing 1 - 3 of 3
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Effect of the Firing Temperatures on the Phase Evolution and Electrical Properties of 0.85[0.94Bi0.5Na0.5TiO3-0.06BaTiO3]-0.15[Na0.73Bi0.09NbO3] Ceramics Synthesized via the Solid-State Combustion Method
    (2023-01-01)
    Pattanakasem, Wiwat
    ;
    Yotthuan, Surirat
    ;
    Hongsamsibjed, Pakornkiat
    ;
    Suriwong, Tawat
    ;
    Prasertpalichat, Sasipohn
    In this research paper, we describe 0.85[0.94Bi<inf>0.5</inf>Na<inf>0.5</inf>TiO<inf>3</inf>-0.06BaTiO<inf>3</inf>]-0.15[Na<inf>0.73</inf>Bi<inf>0.09</inf>NbO<inf>3</inf>] (BNT-BT-NBN) ceramics fabricated by the solid-state combustion technique. The phase evolution, microstructure, dielectric, ferroelectric and energy storage properties were examined. The BNT-BT-NBN powders and ceramics were calcined and sintered between 650–900 °C and 1100–1175 °C, respectively, for 2 h. All samples showed a typical perovskite structure, as revealed by X-ray diffraction. The Rietveld refinement analysis of the ceramics suggested the samples sintered between 1100 and 1150 °C had coexisting R + T phases, while the R + T+C phases were observed in the ceramics sintered at 1175 °C. The average grain size of the samples increased from 0.52 to 1.39 μm with increased sintering temperature. The density of the ceramics increased from 5.12 to 5.45 g/cm<sup>3</sup> when the sintering temperature increased from 1100 to 1150 °C, and then decreased. Increasing the sintering temperature from 1100 to 1150 °C caused the dielectric constant at T <inf>s</inf> (ε <inf>s</inf>) and the dielectric constant at T <inf>m</inf> (ε <inf>m</inf>) to increase from 1727 to 1945 and 1564 to 1750, respectively, and then ε <inf>s</inf> and ε <inf>m</inf> declined. All BNT-BT-NBN ceramics had good dielectric temperature stability with only a±10% change when the temperature ranged from room temperature to ∼300 °C. The optimum energy-storage properties (W <inf>rec</inf> = 0.62 J/cm<sup>3</sup> and η = 83.2%) were obtained from the BNT-BT-NBN ceramics sintered at 1150 °C for 2 h. This data indicates that BNT-BT-NBN ceramics can be useful as lead-free materials for high density energy-storage capacitors.
      3
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Phase evolution, microstructure and electrical response of KNNT ceramics with Li+ substitution and doping
    (2022-01-01)
    Yotthuan, Surirat
    ;
    Udeye, Thanya
    ;
    Prasertpalichat, Sasiphon
    ;
    Pulphol, Phieraya
    ;
    Vittayakorn, Naratip
    Lead-free (K<inf>0.5</inf>Na<inf>0.5</inf>)(Nb<inf>0.7</inf>Ta<inf>0.3</inf>)O<inf>3</inf> (KNNT) ceramics with Li<sup>+</sup> substitution (KN<inf>0.5-x</inf>Li<inf>x</inf>NT) and direct (KNNT-xLi) doping at x = 0, 0.01, 0.02, 0.03 and 0.04 mol% were synthesized by the solid-state combustion route. The phase, microstructure, dielectric and ferroelectric properties of the ceramics were examined. The XRD pattern of the ceramics revealed orthorhombic and tetragonal phases in all specimens. The Rietveld refinement procedure showed that increasing either the Li<sup>+</sup> substitution or doping levels enhanced the amount of the tetragonal phase. It was found that Li<sup>+</sup> doping, either substitutional or additional, enhanced the Curie temperature (T <inf>C</inf>) by increasing the tetragonal distortion, while the dielectric constant (ε <inf>C</inf>) decreased. The good remanent P-E loops of the KN<inf>0.5-x</inf>Li<inf>x</inf>NT ceramics were found with x = 0.01 (P <inf>r</inf>∼10.89 µC/cm<sup>2</sup> and E <inf>C</inf>∼13.09 kV/cm), while for KNNT-xLi ceramics, it was obtained with x = 0.02 (P <inf>r</inf>∼15.65 µC/cm<sup>2</sup> and E <inf>C</inf>∼11.46 kV/cm), which were confirmed by remanent P-E hysteresis measurements.
      1
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    The influences of Cs+ substitution and direct doping on the phase evolution, microstructure and electrical properties of KNNT ceramics
    (2021-01-01)
    Yotthuan, Surirat
    ;
    Udeye, Thanya
    ;
    Vittayakorn, Naratip
    ;
    Eitssayeam, Sukum
    ;
    Pulphol, Phieraya
    The effects of Cs<sup>+</sup> substitution and direct doping in (K<inf>0.5</inf>Na<inf>0.5</inf>)(Nb<inf>0.7</inf>Ta<inf>0.3</inf>)O<inf>3</inf> (KNNT) ceramics, on the crystal structure, microstructure and electrical properties were investigated. Both the KNNT with Cs<sup>+</sup> substitution (K<inf>0.5-x</inf>Cs<inf>x</inf>NNT) and addition (KNNT-xCs) (x = 0, 0.01, 0.02, 0.03 and 0.04 mol%) were synthesized by the solid-state combustion technique using glycine as fuel. All samples were sintered at 1130–1150 °C for 4 h. The x-ray diffraction (XRD) analysis for the ceramics revealed the presence of orthorhombic (O) and tetragonal (T) phases in all samples. Increasing both the Cs<sup>+</sup> substitution and doping amounts, enhanced the content of orthorhombic phase, as verified by the Rietveld refinement technique. It was found that Cs<sup>+</sup> doping, either substitutional or additional, strongly decreased their density, dielectric and ferroelectric properties. The undoped KNNT ceramic exhibited well-saturated P-E hysteresis loop. With Cs<sup>+</sup> doping, the samples became unsaturated and a leakage current was produced. The KNNT-xCs ceramics demonstrated higher density and dielectric properties than the K<inf>0.5-x</inf>Cs<inf>x</inf>NNT ceramics.