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<p>BiLaMnGdO₆ double perovskite ceramics were successfully synthesized by the solid-state reaction method and structurally characterized using Rietveld refinement of XRD data. The analysis confirmed an orthorhombic perovskite structure (space group <i>Pnma</i>) with refined lattice parameters <i>a</i> = 5.5552 Å, <i>b</i> = 7.8784 Å, <i>c</i> = 5.5543 Å, and unit cell volume of 243.0882 ų. The average crystallite size was estimated at ~ 413&#xa0;nm, with microstrain ε ≈ 0.0015 and dislocation density δ ≈ 1.32 × 10⁻⁷ m⁻², reflecting good crystallinity and low defect concentration. Dielectric spectroscopy revealed a strong frequency- and temperature-dependent response: ε′ decreased with frequency, saturating to ε′∞ at high frequencies, while ε′ exceeded 1000 above 300&#xa0;°C at low frequencies due to space charge and defect-driven polarization. AC conductivity followed Jonscher’s law, indicating hopping-dominated transport with a transition from correlated barrier hopping to long-range conduction as temperature increased. The complex electric modulus analysis (M′, M″) exhibited Debye-like but non-ideal relaxation, with relaxation peaks shifting from 10² Hz (300&#xa0;°C) to 10³ Hz (450&#xa0;°C) and activation energy of ~ 0.45&#xa0;eV attributed to small-polaron hopping between Mn³⁺/Mn⁴⁺ sites. Cole–Cole fitting yielded relaxation times in the 10⁻⁸ s range and cut-off frequencies of 2.4–3.3&#xa0;MHz (400–450&#xa0;°C). Importantly, the material exhibited a negative temperature coefficient of resistance (TCR ≈ − 1.53 × 10⁻³ °C⁻¹) and thermistor constants β ≈ 2466&#xa0;K (350–400&#xa0;°C) and 2113&#xa0;K (400–450&#xa0;°C), consistent with NTC thermistor behavior. These findings demonstrate that BiLaMnGdO₆ ceramics possess high dielectric constant, MHz-range relaxation dynamics, and semiconducting thermistor characteristics, making them promising candidates for high-frequency capacitors, RF sensors, and temperature-sensitive electronic devices.</p>

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Synthesis and Analysis of BiLaMnGdO6 Ceramic for Potential Industrial Applications

  • 期刊论文

  • 发表日期：

    2025年10月16日

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  • Pratiksha Agnihotri,
  • Shilpa Kumari,
  • Rahul Goel,
  • Radheshyam Rai,
  • Chander Prakash

摘要

BiLaMnGdO₆ double perovskite ceramics were successfully synthesized by the solid-state reaction method and structurally characterized using Rietveld refinement of XRD data. The analysis confirmed an orthorhombic perovskite structure (space group Pnma) with refined lattice parameters a = 5.5552 Å, b = 7.8784 Å, c = 5.5543 Å, and unit cell volume of 243.0882 ų. The average crystallite size was estimated at ~ 413 nm, with microstrain ε ≈ 0.0015 and dislocation density δ ≈ 1.32 × 10⁻⁷ m⁻², reflecting good crystallinity and low defect concentration. Dielectric spectroscopy revealed a strong frequency- and temperature-dependent response: ε′ decreased with frequency, saturating to ε′∞ at high frequencies, while ε′ exceeded 1000 above 300 °C at low frequencies due to space charge and defect-driven polarization. AC conductivity followed Jonscher’s law, indicating hopping-dominated transport with a transition from correlated barrier hopping to long-range conduction as temperature increased. The complex electric modulus analysis (M′, M″) exhibited Debye-like but non-ideal relaxation, with relaxation peaks shifting from 10² Hz (300 °C) to 10³ Hz (450 °C) and activation energy of ~ 0.45 eV attributed to small-polaron hopping between Mn³⁺/Mn⁴⁺ sites. Cole–Cole fitting yielded relaxation times in the 10⁻⁸ s range and cut-off frequencies of 2.4–3.3 MHz (400–450 °C). Importantly, the material exhibited a negative temperature coefficient of resistance (TCR ≈ − 1.53 × 10⁻³ °C⁻¹) and thermistor constants β ≈ 2466 K (350–400 °C) and 2113 K (400–450 °C), consistent with NTC thermistor behavior. These findings demonstrate that BiLaMnGdO₆ ceramics possess high dielectric constant, MHz-range relaxation dynamics, and semiconducting thermistor characteristics, making them promising candidates for high-frequency capacitors, RF sensors, and temperature-sensitive electronic devices.