Current Understanding of Structure–Processing–Property Relationships in BaTiO 3 –Bi( M )O 3 Dielectrics

Case Study on a Representative System we present a detailed structural study on the system BT-xBZT, which is a representative BT-Bi(M)O3 system.69

Michaela A. Beuerlein; Nitish Kumar; Tedi‐Marie Usher; Harlan James Brown‐Shaklee; Natthaphon Raengthon; Ian M. Reaney; David P. Cann; Jacob L. Jones; Geoff L. Brennecka

2016

Scholarcy highlights

  • In the continual quest for increased integration, efficiency, and process monitoring, electronics systems are being subjected to increasingly harsh operating conditions
  • Devices built around wide bandgap semiconductors such as SiC and GaN can operate with greater efficiency, higher frequencies, and higher powers than their Si-based counterparts, but even these more efficient devices dissipate sufficient heat that active cooling is often required in order to accommodate the operating temperature limitations of nearby passive components such as capacitors
  • The frequency- and temperature-dependent dielectric response of these materials can be described by the Curie-Weiss and polar nano-regions model applied to traditional relaxors, but Vogel-Fulcher analysis reveals activation energies that are roughly an order of magnitude higher than in traditional relaxors, related to the unusual temperature stability of permittivity above temperature of maximum permittivity
  • Raengthon et al saw very little difference in performance between 0.5BT0.25BZT-0.25BS pellets and multilayer cofired ceramic of the same composition cofired with 0.7Ag-0.3Pd electrodes at 1000 °C.15. To explore this phenomenon further, we report here the case study on the cofiring of physically large high voltage MLCCs consisting of 0.8BT0.2BZT dielectric layers with Pt electrodes
  • It has been argued that the PNRs form due to random fields generated as a result of structural and charge inhomogeneities driven by homogeneous or heterogeneous cation substitutions on the A-site or B-site in the parent normal ferroelectric, and that the random interaction between the PNRs is key to the destabilization of domains
  • Significant additions of Bi2O3 reduce the processing temperatures required for BaTiO3- and SrTiO3-based dielectrics, and impose severe restrictions on electrode compatibility for cofiring because Bi2O3 is thermodynamically incompatible with both metallic Ni and Cu, and Bi-based species are known to react aggressively with both Pt and Pd at common sintering temperatures
  • Multiple groups have successfully demonstrated the cofiring of BT-Bi(M)O3 dielectrics with Ag-Pd electrodes, and efforts to extend the temperature, atmosphere, and electrode compatibility of these dielectrics are ongoing

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