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High-Temperature Dielectric Relaxation and Electric Conduction Mechanisms in a LaCoO3-Modified Na0.5Bi0.5TiO3 System
Surinder Singh1, Anumeet Kaur1,2, Parwinder Kaur1
1Department of Physics, Guru Nanak Dev University, Amritsar 143005, Punjab, India.
ACS Omega
|July 24, 2023
Summary
This study investigates dielectric properties in LaCoO3-Na0.5Bi0.5TiO3 ceramics. Oxygen vacancies drive relaxation and conduction, influencing electrical behavior and magnetoelectric response.
Area of Science:
- Materials Science
- Solid State Physics
- Ceramic Engineering
Background:
- Perovskite titanates like Na0.5Bi0.5TiO3 exhibit ferroelectric properties.
- Doping with rare-earth cobaltates can modify dielectric and electrical characteristics.
- Understanding dielectric relaxation and conduction mechanisms is crucial for device applications.
Purpose of the Study:
- To investigate the high-temperature dielectric relaxation and electric conduction mechanisms in (x)LaCoO3-(1-x)Na0.5Bi0.5TiO3 ceramics.
- To determine the influence of LaCoO3 doping on the dielectric transitions and electrical transport in Na0.5Bi0.5TiO3.
- To explore the relationship between oxygen vacancies and the observed dielectric and conduction phenomena.
Main Methods:
- Synthesis of (x)LaCoO3-(1-x)Na0.5Bi0.5TiO3 ceramic samples with varying x values (0.05, 0.10, 0.15).
- High-temperature dielectric measurements as a function of frequency.
- Impedance spectroscopy and modulus spectroscopy for analyzing relaxation and conduction.
- Conductivity studies to understand charge transport phenomena.
Main Results:
- All samples showed two dielectric transitions: a low-temperature transition associated with polar nanoregions (PNRs) and a higher-temperature ferroelectric to paraelectric transition (Curie temperature, Tc).
- Impedance analysis indicated a negative temperature coefficient of resistance (NTCR) behavior.
- Modulus spectroscopy revealed broad, asymmetric relaxation peaks, suggesting non-Debye-type relaxation.
- Oxygen vacancies, introduced by LaCoO3 doping, were identified as the primary cause of relaxation and conduction, with doubly ionized oxygen vacancies acting as charge carriers.
- A negative magnetodielectric response was observed in most samples.
Conclusions:
- The addition of LaCoO3 to Na0.5Bi0.5TiO3 significantly influences its dielectric and electrical properties.
- Oxygen vacancies play a critical role in the observed dielectric relaxation, electrical conduction, and magnetoelectric effects.
- The materials exhibit complex relaxation dynamics and NTCR behavior, offering potential for advanced electronic applications.
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