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<p>To develop lead-free dielectric ceramics with favorable dielectric temperature stability, lead-free ferroelectric ceramics with the composition of (1 − <i>x</i>)BaTiO<sub>3</sub> − <i>x</i>Bi[(Zn<sub>2/3</sub>Ta<sub>1/3</sub>)<sub>1−0.15<i>x</i></sub>Nb<sub>0.15<i>x</i></sub>]O<sub>3+0.15<i>x</i></sub> (<i>x</i> = 0–0.3) were successfully synthesized via the solid-state reaction method. The effects of BZTN doping content on the microstructural structure, dielectric properties and ferroelectric properties of the ceramics were systematically investigated. The results show that all samples exist as single-phase perovskite solid solutions and their crystalline structure transforms from tetragonal (P4mm) to pseudo-cubic-like (Pm <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\overline{3}\)</EquationSource> <EquationSource Format="MATHML"><math> <mover> <mn>3</mn> <mo>¯</mo> </mover> </math></EquationSource> </InlineEquation> m) symmetry when <i>x</i> ≥ 0.1. According to the microscopic analysis, BZTN doping can effectively suppress abnormal grain growth and decrease the average grain size. The ferroelectric-paraelectric phase transition temperature and maximum dielectric constant decrease with the increase of doping content. As the BZTN addition content increases, (1 − <i>x</i>)BT − <i>x</i>BZTN system transforms from normal ferroelectrics to relaxor ferroelectrics, which is characterized by pronounced diffuse phase transition and enhanced frequency dispersion. The phase transition exponent γ rises rapidly from 1.40892 at<i> x</i> = 0 to1.98575 at <i>x</i> = 0.10 and the frequency dispersion Δ<i>T</i><sub>rs</sub> increases from none for undoped BaTiO<sub>3</sub> samples to 58.5&#xa0;°C for those with <i>x</i> = 0.3. Based on the Vogel–Fulcher analysis, the attempt frequency ν₀ increases systematically with BZTN content and the activation energy <i>E</i>ₐ exhibits a pronounced increase from 0.0207&#xa0;eV at <i>x</i> = 0.10 to 0.1441&#xa0;eV at <i>x</i> = 0.3 with the freezing temperature <i>T</i><sub>VF</sub> decreasing monotonically from 263.7&#xa0;K at <i>x</i> = 0.1 to 165.7&#xa0;K at <i>x</i> = 0.3. The ferroelectric hysteresis loops after initial BZTN doping also confirm the intensified relaxor characteristics in terms of the decrease in remanent polarization (<i>P</i><sub>r</sub>), the maximum polarization (<i>P</i><sub>m</sub>) and coercive field (<i>E</i><sub>c</sub>). The 0.8BT–0.2BZTN ceramic exhibit comprehensive properties: practical permittivity (<i>ε</i>ᵣ<sub>RT</sub> = 899), low dielectric loss (tan<i>δ</i><sub>RT</sub> = 0.0112) and fine dielectric temperature stability (<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\Delta \varepsilon_{{\text{r}}} /\varepsilon_{{\text{r}}} = - 20.9\% \sim + 0.3\%\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="normal">Δ</mi> <msub> <mi>ε</mi> <mtext>r</mtext> </msub> <mo stretchy="false">/</mo> <msub> <mi>ε</mi> <mtext>r</mtext> </msub> <mo>=</mo> <mo>-</mo> <mn>20.9</mn> <mo>%</mo> <mo>∼</mo> <mo>+</mo> <mn>0.3</mn> <mo>%</mo> </mrow> </math></EquationSource> </InlineEquation>) in the wide temperature range of − 55 ~ 150&#xa0;°C meeting the EIA X8S standard, therefore, is expected to be applied in multilayer ceramic capacitors under wide temperature ranges.</p>

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Excellent dielectric temperature stability of BaTiO3-based lead-free ferroelectric ceramics with enhanced relaxor behavior

  • 期刊论文

  • 发表日期：

    2026年6月27日

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  • Chenglin Wang,
  • Vendish Kweku Ennin,
  • Ke Zhang,
  • Ruixuan Wang,
  • Abudulai Nancy Bawah,
  • Chen Zhang

摘要

To develop lead-free dielectric ceramics with favorable dielectric temperature stability, lead-free ferroelectric ceramics with the composition of (1 − x)BaTiO3 − xBi[(Zn2/3Ta1/3)1−0.15xNb0.15x]O3+0.15x (x = 0–0.3) were successfully synthesized via the solid-state reaction method. The effects of BZTN doping content on the microstructural structure, dielectric properties and ferroelectric properties of the ceramics were systematically investigated. The results show that all samples exist as single-phase perovskite solid solutions and their crystalline structure transforms from tetragonal (P4mm) to pseudo-cubic-like (Pm \(\overline{3}\) 3 ¯ m) symmetry when x ≥ 0.1. According to the microscopic analysis, BZTN doping can effectively suppress abnormal grain growth and decrease the average grain size. The ferroelectric-paraelectric phase transition temperature and maximum dielectric constant decrease with the increase of doping content. As the BZTN addition content increases, (1 − x)BT − xBZTN system transforms from normal ferroelectrics to relaxor ferroelectrics, which is characterized by pronounced diffuse phase transition and enhanced frequency dispersion. The phase transition exponent γ rises rapidly from 1.40892 at x = 0 to1.98575 at x = 0.10 and the frequency dispersion ΔTrs increases from none for undoped BaTiO3 samples to 58.5 °C for those with x = 0.3. Based on the Vogel–Fulcher analysis, the attempt frequency ν₀ increases systematically with BZTN content and the activation energy Eₐ exhibits a pronounced increase from 0.0207 eV at x = 0.10 to 0.1441 eV at x = 0.3 with the freezing temperature TVF decreasing monotonically from 263.7 K at x = 0.1 to 165.7 K at x = 0.3. The ferroelectric hysteresis loops after initial BZTN doping also confirm the intensified relaxor characteristics in terms of the decrease in remanent polarization (Pr), the maximum polarization (Pm) and coercive field (Ec). The 0.8BT–0.2BZTN ceramic exhibit comprehensive properties: practical permittivity (εᵣRT = 899), low dielectric loss (tanδRT = 0.0112) and fine dielectric temperature stability ( \(\Delta \varepsilon_{{\text{r}}} /\varepsilon_{{\text{r}}} = - 20.9\% \sim + 0.3\%\) Δ ε r / ε r = - 20.9 % ∼ + 0.3 % ) in the wide temperature range of − 55 ~ 150 °C meeting the EIA X8S standard, therefore, is expected to be applied in multilayer ceramic capacitors under wide temperature ranges.