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Preparation, structure and dielectric properties of ceramic- polymer composites / Shaimaa Mohammad Mohammad Behery ; Supervised Ezeldain Shafee , Mamdooh Abdelfattah Eissa

By: Contributor(s): Material type: TextTextLanguage: English Publication details: Cairo : Shaimaa Mohammad Mohammad Behery , 2016Description: 116 P. : charts , facsimiles ; 25cmOther title:
  • تحضير وتركيب وخصائص العزل الكهربي لمخاليط البوليمر و السيراميك [Added title page title]
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Dissertation note: Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Physical Chemistry Summary: 0-3 ceramic-polymer composites using both micro-size and nano-size ceramic particles were studied. The micro-size ceramic particles with general formula Ba₀.95Ca₀.₀₅Ti₀.8Zr₀.₂O₃(BCZT) were prepared by solid state method. BCZT/P(VDF-TrFE) 0-3 composites with various BCTZ volume fractions were fabricated using the combined method of solvent casting and hot pressing. The structural, morphological, dielectric, ferroelectric, piezoelectric,and pyroelectric properties of BCZT/P(VDF-TrFE composites and their dependencies on the BCTZ volume fraction were investigated and discussed. It was found that the dielectric properties of these composites could be tuned by varying the volume fraction of the BCZT particles. A higher dielectric constant of up to 90 and a dielectric loss down to 0.024 could be obtained at 1 kHz for a BCZT volume fraction of 0.4. All composites show a higher Psat than the pure copolymer, which can be attributed to the contribution of BCZT. Composites with lower ceramic volume fraction (less than 0.2) show a little decrease in coercive field and obvious increase in remnant polarization. With an increase in ceramic volume fraction from 0.05 to 0.2, the remanent polarization increases from about 8.6 to 11.0 oC cm⁻² and the coercive field decreases from 0.41 to 0.32 MV cm-1. The composites with higher ceramic volume fractions showed a remanent polarization of ~ 12 oC cm⁻², but the coercive field reduced significantly (~ 0.125 MV cm-1 for the composite with {uF066}cer = 0.4). Under parallel poling, the pyroelectric contributions from the two phases reinforced while piezoelectric contribution partially canceled each other. Therefore the investigated composites are suitable for pyroelectric applications as the composite sensor will be less sensitive to mechanical vibrations. Sodium nobiate (NaNbO3) nanowire as nano-size ceramic fillers were synthesized by a hydrothermal synthesis assisted with P123 and their 0-3 NaNbO3/(PVDF-HFP) nanocomposite thin films were fabricated via a simple solution cast method
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Thesis Thesis قاعة الرسائل الجامعية - الدور الاول المكتبة المركزبة الجديدة - جامعة القاهرة Cai01.12.11.Ph.D.2016.Sh.P (Browse shelf(Opens below)) Not for loan 01010110070024000
CD - Rom CD - Rom مخـــزن الرســائل الجـــامعية - البدروم المكتبة المركزبة الجديدة - جامعة القاهرة Cai01.12.11.Ph.D.2016.Sh.P (Browse shelf(Opens below)) 70024.CD Not for loan 01020110070024000

Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Physical Chemistry

0-3 ceramic-polymer composites using both micro-size and nano-size ceramic particles were studied. The micro-size ceramic particles with general formula Ba₀.95Ca₀.₀₅Ti₀.8Zr₀.₂O₃(BCZT) were prepared by solid state method. BCZT/P(VDF-TrFE) 0-3 composites with various BCTZ volume fractions were fabricated using the combined method of solvent casting and hot pressing. The structural, morphological, dielectric, ferroelectric, piezoelectric,and pyroelectric properties of BCZT/P(VDF-TrFE composites and their dependencies on the BCTZ volume fraction were investigated and discussed. It was found that the dielectric properties of these composites could be tuned by varying the volume fraction of the BCZT particles. A higher dielectric constant of up to 90 and a dielectric loss down to 0.024 could be obtained at 1 kHz for a BCZT volume fraction of 0.4. All composites show a higher Psat than the pure copolymer, which can be attributed to the contribution of BCZT. Composites with lower ceramic volume fraction (less than 0.2) show a little decrease in coercive field and obvious increase in remnant polarization. With an increase in ceramic volume fraction from 0.05 to 0.2, the remanent polarization increases from about 8.6 to 11.0 oC cm⁻² and the coercive field decreases from 0.41 to 0.32 MV cm-1. The composites with higher ceramic volume fractions showed a remanent polarization of ~ 12 oC cm⁻², but the coercive field reduced significantly (~ 0.125 MV cm-1 for the composite with {uF066}cer = 0.4). Under parallel poling, the pyroelectric contributions from the two phases reinforced while piezoelectric contribution partially canceled each other. Therefore the investigated composites are suitable for pyroelectric applications as the composite sensor will be less sensitive to mechanical vibrations. Sodium nobiate (NaNbO3) nanowire as nano-size ceramic fillers were synthesized by a hydrothermal synthesis assisted with P123 and their 0-3 NaNbO3/(PVDF-HFP) nanocomposite thin films were fabricated via a simple solution cast method

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