Dissertation > Excellent graduate degree dissertation topics show

Structures and Giant Dielectric Response of Modified CaCu3Ti4O12 and Related Ceramics

Author: WangYing
Tutor: ChenXiangMing
School: Zhejiang University
Course: Materials Science and Engineering
Keywords: CaCu3Ti4O12 giant dielectric constant dielectric characteristics mixed-valent structure microstructures
CLC: TQ174.756
Type: Master's thesis
Year: 2011
Downloads: 68
Quote: 0
Read: Download Dissertation

Abstract


Giant dielectric constant materials show great potential in the applications for miniaturization of microelectronic devices. CaCu3Ti4O12 is one of the most typical giant dielectric materials. It indicates a giant dielectric constant which keeps temperature and frequency-independent. So far, intensive investigations have been focused on its giant dielectric characteristics. To investigate the origin of the giant dielectric response in CaCu3Ti4O12 and modify its dielectric characteristics, Nd-substituted CaCu3Ti4O12 and related ceramics were prepared and their structure, microstructure and dielectric characteristics were evaluated.First, Ca1-3x/2NdxCu3Ti4O12 (x=0,0.1,0.2) ceramics were prepared by a solid state reaction process and single-phase structures were obtained for all the compositions. Dielectric characteristics of the present ceramics were evaluated in a broad range of temperature and frequency. Two significant dielectric relaxations were observed in the low and high temperature ranges. The low temperature dielectric relaxation following Arrhenius law, should be ascribed to the more intrinsic mechanisms where the mixed-valent structures of Cu+/Cu2+ and Ti3+/Ti4+ might play important roles. Dielectric characteristics of the present ceramics were modified through modifying the mixed-valent structures by Nd-substitution.Dielectric characteristics of Ca1-3x/2NdxCu3Ti4O12 (x=0,0.1,0.2) ceramics sintered at various temperatures were also investigated. For samples with x=0.1, the processing dependence of dielectric characteristics was significant controlled. The samples with x=0.1 sintered at various temperatures maintained stable dielectric characteristics even though great changes took place in microstructures. Structure characteristics of the present ceramics were further investigated. Comparing with other compositions, TiO6 octahedron in the samples with x=0.1 tilted less. Correspondingly, Ti-O distance was the smallest. Such compact structure might be responsible for the controlled processing dependence of dielectric characteristics in such sample.SrCu3Ti4O12 ceramics were prepared by a solid state reaction process, and the SrCu3Ti4O12 major phase combined with minor amount of SrTiO3 and CuO secondary phase were observed in the present ceramics. A significant dielectric relaxation was observed at low temperature which should originate from some intrinsic mechanism. Comparing with Ca1-3x/2NdxCu3Ti4O12(x=0,0.1,0.2) ceramics, the conductivity of SrCu3Ti4O12 ceramics at room temperature was significantly decreased.

Related Dissertations

  1. Research on Welding Characteristics of CO2 Laser-GMA Hybrid Welding for Ultra-Low Carbon Bainitic Steel,TG456.7
  2. High Efficiency Embedded Processor IP Core,TP332
  3. Research on Microstructure and Properties of Ti(C, N)-based Cermets Coated by Multivariant Nitrides,TG174.4
  4. Packaging Light Extraction Efficiency Enhancement of LED Array Packaging with Various Micro-structures,TN312.8
  5. Ultra-deep with high strength and high toughness V150 Casing Heat Treatment Process,TG156.3
  6. Influence of Rolling and Cooling Processes on Microstructures and Mechanical Properties of 500MPa Steel Strip for Automobiles,TG335.5
  7. Heating system and hot deformation parameters on the microstructure and properties of X80 pipeline steel impact study,TG335.11
  8. Design of Grinding and Polishing System for Thin-Walled Microstructures and Study on Processing,TG580.6
  9. On Microstructures and Properties of Recycled Composites,TB331
  10. Study on the Aging Behavior of Al-Sc-Zr Alloys,TG146.21
  11. Study on Rolling Technology of Mg-9Li-2Zn Alloys and Their Microstructures and Mechanical Properties,TG39
  12. Formation and Magnetic Pulsing Effect of High Temperature Soft Magnetic Fe(Co)-Hf-B-Cu Alloys,TG139.8
  13. Controlled Synthesis, Characterization and Performce of Ceria or Yttria Micro/Nanostructures,TB383.1
  14. Synthesis and Dielectric Properties of Rare Earth Doped Calaium Copper Titanate,TQ174.12
  15. Deposition and Optical Properties of Doped Nano-Silicon Carbide Thin Films,O613.72
  16. Study on Damage Actions of Alkali-resistant Glass Fiber in Cement-based Materials,U414
  17. Influence of a Buffer Layer on the Properties of the ZnO Films Prepared on Si and Glass Substrates,O484.4
  18. Pulse Current Sintering and Formability of NiAl Alloy Powder,TG146.15
  19. Microstructure, Mechanical Properties and Heat Transfer on the Moulding of PP Tape,TQ325.14
  20. Micro- structure compound ultrasonic power processing technology,TG661
  21. Key Technology Study of Grinding and Polishing Equipment for Thin-Walled Microstructures,TG580.23

CLC: > Industrial Technology > Chemical Industry > Silicate > Ceramic Industry > Ceramics > Industrial ceramic > Electronic industrial ceramics
© 2012 www.DissertationTopic.Net  Mobile