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<p>Lead-free perovskite ceramics Sr<sub>1-x</sub>Na<sub>x</sub>(Sn<sub>0.25</sub>Ti<sub>0.75</sub>)<sub>1-x</sub>Nb<sub>x</sub>O<sub>3</sub> (0.6 ≤ <i>x</i> ≤ 0.9), denoted SNSTNₓ, were synthesized by the conventional solid-state route and sintered at 1350&#xa0;°C. X-ray diffraction analysis confirms the formation of a single-phase perovskite structure with tetragonal symmetry (space group <i>P4mm</i>) for all compositions. Dielectric measurements performed as a function of temperature and frequency reveal two distinct electrical behaviors depending on composition. Samples with <i>x</i> ≥ 0.8 exhibit classical ferroelectric characteristics with a well-defined, frequency-independent Curie temperature, whereas compositions with <i>x</i> &lt; 0.8 show relaxor-like behavior characterized by diffuse phase transitions and strong frequency dispersion of the dielectric permittivity. The relaxor nature is further supported by deviation from the Curie–Weiss law and a diffuseness parameter <i>γ</i> ≈ 1.7. Ferroelectric hysteresis measurements performed for <i>x</i> = 0.9 confirm ferroelectricity, with a remanent polarization of 0.0125 µF mm⁻<sup>2</sup> and a coercive field of 5&#xa0;V&#xa0;mm⁻<sup>1</sup>. The observed evolution of dielectric behavior is attributed to structural disorder induced by simultaneous A-site (Sr<sup>2</sup>⁺/Na⁺) and B-site (Sn<sup>4</sup>⁺/Ti<sup>4</sup>⁺/Nb<sup>5</sup>⁺) substitutions, which modify lattice distortion and reduce the phase transition temperature. These results indicate that SNSTNₓ ceramics are promising lead-free materials for temperature-stable dielectric applications.</p>

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Effect of the addition of Sr(Sn0.25Ti0.75)O3 on the dielectric properties in NaNbO3

  • 期刊论文

  • 发表日期：

    2026年1月20日

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  • Imane Layaida,
  • Samia Aydi,
  • Souad Chkoundali,
  • Abdelhedi Aydi

摘要

Lead-free perovskite ceramics Sr1-xNax(Sn0.25Ti0.75)1-xNbxO3 (0.6 ≤ x ≤ 0.9), denoted SNSTNₓ, were synthesized by the conventional solid-state route and sintered at 1350 °C. X-ray diffraction analysis confirms the formation of a single-phase perovskite structure with tetragonal symmetry (space group P4mm) for all compositions. Dielectric measurements performed as a function of temperature and frequency reveal two distinct electrical behaviors depending on composition. Samples with x ≥ 0.8 exhibit classical ferroelectric characteristics with a well-defined, frequency-independent Curie temperature, whereas compositions with x < 0.8 show relaxor-like behavior characterized by diffuse phase transitions and strong frequency dispersion of the dielectric permittivity. The relaxor nature is further supported by deviation from the Curie–Weiss law and a diffuseness parameter γ ≈ 1.7. Ferroelectric hysteresis measurements performed for x = 0.9 confirm ferroelectricity, with a remanent polarization of 0.0125 µF mm⁻2 and a coercive field of 5 V mm⁻1. The observed evolution of dielectric behavior is attributed to structural disorder induced by simultaneous A-site (Sr2⁺/Na⁺) and B-site (Sn4⁺/Ti4⁺/Nb5⁺) substitutions, which modify lattice distortion and reduce the phase transition temperature. These results indicate that SNSTNₓ ceramics are promising lead-free materials for temperature-stable dielectric applications.