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Author: search.filters.author.Bongkarn, TheerachaiSubject: search.filters.subject.Piezoelectric

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    Piezoelectric composite films for real-time foot strike detection and energy generation
    (2025-12-16)
    Panpho, Phakakorn
    ;
    Charoonsuk, Thitirat
    ;
    Vittayakorn, Naratip
    ;
    Charoenthai, Nipaphat
    ;
    Bongkarn, Theerachai
    Energy harvesting technology integrated into running shoes enables the conversion of mechanical energy from foot strikes into electrical signals for real-time monitoring. This approach enhances running efficiency, reduces injury risk, and eliminates the need for external power sources. In this study, composite films combining lead-free piezoelectric ceramics (KNNS-BNZ-xBF) with PDMS were developed for efficient energy harvesting and accurate detection of foot-strike patterns. XRD analysis revealed a broad R–O–T phase coexistence zone (0 ≤ x ≤ 0.006) and a transition to an R–T phase boundary for x > 0.006, with reduced grain size as xBF increased. The sample with xBF = 0.006 mol.% showed optimal electrical properties and was selected for composite film fabrication. Electrical output increased with ceramic loading, reaching maximum open-circuit voltage (V<inf>OC</inf>) and short-circuit current (I<inf>SC</inf>) at 18 wt% KBB due to enhanced piezoelectric response and uniform particle dispersion. The films, mounted on running shoe soles, successfully detected different foot-strike patterns (heel strike, midfoot, and forefoot). This system demonstrates strong potential for wearable sensors in athletic monitoring and injury prevention.
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    Physical and piezoelectric properties of ceramics in the (K0.5Na0.5)NbO3–Bi(Zn0.5Ti0.5)O3–PbTiO3 system
    (2018-01-01)
    Prasatkhetragarn, Anurak
    ;
    Phetphum, Natthaporn
    ;
    Bongkarn, Theerachai
    ;
    Vittayakorn, Naratip
    ;
    Maensiri, Santi
    Piezoelectric ceramic materials in xKNN–yBZT–(1-x-y)PT system, when both of x and y were varied from 0.05 to 0.20, were prepared by a solid state reaction technique. Phase formation, microstructure, density, ferroelectric and piezoelectric properties of the specimens were investigated. The powders were calcined and sintered at the temperature of 900 oC for 6 h and 1050 oC for 2 h, respectively, to obtain single phase perovskite structures. The results indicated that the crystal structure of xKNN–yBZT–(1-xy)PT ceramics system changed from tetragonal to monoclinic phase while the secondary phase of PbTi2O7 was present at the composition of point 5 (0.2KNN–0.1BZT–0.7PT). The densities of the specimens tended to decrease with increasing KNN content. However, the densities and average grain sizes of their ceramics increased with increasing BZT content. In addition, the maximum values of piezoelectric and ferroelectric properties were achieved in 0.05KNN–0.05BZT–0.9PT compound, likely caused by the grain size effects.
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    Structural, microstructure and electrical properties of La2O3-doped Bi0.5(Na0.68K0.22Li0.1)0.5TiO3 lead-free piezoelectric ceramics synthesized by the combustion technique
    (2015-07-01)
    Bhupaijit, Pamornnarumol
    ;
    Kornphom, Chittakorn
    ;
    Vittayakorn, Naratip
    ;
    Bongkarn, Theerachai
    The effect of firing temperatures on phase formation, microstructure and physical properties of [Bi<inf>0.5</inf>(Na<inf>0.68</inf>K<inf>0.22</inf>Li<inf>0.1</inf>)<inf>0.5</inf>TiO<inf>3</inf>] doped with La<inf>2</inf>O<inf>3</inf> at 0.1 wt% (BNKLLT) ceramics prepared by the combustion method was studied. Glycine was used as fuel and the ratio of raw material (corresponding oxidant metal nitrate) with fuel was about 1:0.56. The samples were calcined at 600-900 °C for 2 h and sintered at 1075-1150 °C for 2 h. The single rhombohedral peroveskite phase of BNKLLT powders was observed from the sample calcined at 750 °C for 2 h. The BNKLLT ceramics exhibited a pure peroveskite phase in all samples. The microstructures of the BNKLLT powders exhibited an agglomerated form while the grain ceramics exhibited a square shape. The average particle size and average grain size increased with increasing firing temperatures. The density, dielectric constant (ε<inf>r</inf> and ε<inf>m</inf>), P<inf>r</inf> and d<inf>33</inf> tended to increase with increasing sintering temperatures up to 1100 °C and then decreased. The maximum density (5.73 g/cm<sup>2</sup>), maximum dielectric constant (ε<inf>r</inf>~2572 and ε<inf>m</inf>~5536), good ferroelectric properties (P<inf>r</inf>~35.78 μC/cm<sup>2</sup> and E<inf>c</inf>~22.42 kV/cm) and highest d<inf>33</inf> (210 pC/N) were obtained by the sample sintered at 1100 °C for 2 h.