Characteristics of the PTCR in High-Curie-Point Lead-Free Barium Titanate Ceramics and Their Grain Structures

Abstract

The influences of Bi₄Ti₃O₁₂ (BIT) content on the electrical property and the microstructure of Ba_0.998La_0.002TiO₃-based materials have been studied. At a low dopant concentration the grain size is influenced significantly by the donor concentration. With an increase in BIT content the grain size decreases rapidly. All the prepared BIT doping Ba_0.998La_0.002TiO₃-based thermistors show a typical positive temperature coefficient (PTC) effect. As the amount of BIT added in Ba_0.998La_0.002TiO₃-based ceramics increases, the room temperature resistivity appears to exhibit a minimum value. At high BIT content (≥2.0), the room temperature resistivity increased again with increasing BIT content. At a given content of BIT, the influence of sintering temperature on the electrical properties of samples has been investigated.

Keywords:

• Ba_0.998La_0.002TiO₃
• Bi₄Ti₃O₁₂
• Dopant
• Electrical properties
• Lead-free
• Microstructure
• PTC
• Resistivity temperature

ACKNOWLEDGMENTS

We are thankful for support from the National Natural Science Foundation of China (50607013), China Talents Foundation of Ministry of personnel of China (2007), and the Special Scientific Research Fund of Shaanxi Education Bureau (08KJ222).