In situ doping of BaTiO3 and visualization of pressure solution in flux-assisted cold sintering

Cold sintering process (CSP) has attracted great interest due to its extremely low processing temperatures, fast processing times, and simplicity to allow for the densification of ceramics and composites. Understanding the detailed mechanisms underlying low temperature densification is crucial to develop advanced materials and facilitate sustainable and cost-effective industrial implementation to come. Here, by taking BaTiO3 powder and Sr(OH)2·8H2O transient chemical flux as a model system, chemical transformation at solid/flux interfaces driving the dissolution-precipitation creep mechanism were investigated. We demonstrate that Sr(OH)2·8H2O acts both as a sintering flux and a solid solution doping additive, resulting in the formation of BaTiO3 - Ba(1-x)SrxTiO3 with lower Curie temperatures. Using strontium (Sr) as a tracer chemistry, transmission electron microscopy chemical mapping with energy-dispersive X-ray analysis indicates that there is a precipitation of a Ba(1-x)SrxTiO3 mainly at grain/grain interfaces, while grain cores remain undoped. In addition, the difference in the interfacial Sr concentration, which is influenced by the applied uniaxial pressure direction, was clearly observed. This successful visualization of compositional distribution after CSP underlines the significant role of the pressure solution creep in densification process.

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Work Title In situ doping of BaTiO3 and visualization of pressure solution in flux-assisted cold sintering
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Open Access
Creators
  1. Takao Sada
  2. Zhongming Fan
  3. Arnaud Ndayishimiye
  4. Kosuke Tsuji
  5. Sun Hwi Bang
  6. Yoshihiro Fujioka
  7. Clive A. Randall
License In Copyright (Rights Reserved)
Work Type Article
Publisher
  1. Journal of the American Ceramic Society
Publication Date September 7, 2020
Publisher Identifier (DOI)
  1. https://doi.org/10.1111/jace.17461
Deposited August 02, 2022

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  • Created
  • Added Sada-JACERS-46252-Jan2019.pdf
  • Added Creator Takao Sada
  • Added Creator Zhongming Fan
  • Added Creator Arnaud Ndayishimiye
  • Added Creator Kosuke Tsuji
  • Added Creator Sun Hwi Bang
  • Added Creator Yoshihiro Fujioka
  • Added Creator Clive A. Randall
  • Published
  • Updated Work Title, Description Show Changes
    Work Title
    • In situ doping of BaTiO<sub>3</sub> and visualization of pressure solution in flux-assisted cold sintering
    • In situ doping of BaTiO3 and visualization of pressure solution in flux-assisted cold sintering
    Description
    • <p>Cold sintering process (CSP) has attracted great interest due to its extremely low processing temperatures, fast processing times, and simplicity to allow for the densification of ceramics and composites. Understanding the detailed mechanisms underlying low temperature densification is crucial to develop advanced materials and facilitate sustainable and cost-effective industrial implementation to come. Here, by taking BaTiO<sub>3</sub> powder and Sr(OH)<sub>2</sub>·8H<sub>2</sub>O transient chemical flux as a model system, chemical transformation at solid/flux interfaces driving the dissolution-precipitation creep mechanism were investigated. We demonstrate that Sr(OH)<sub>2</sub>·8H<sub>2</sub>O acts both as a sintering flux and a solid solution doping additive, resulting in the formation of BaTiO<sub>3</sub> - Ba<sub>1-</sub><sub>x</sub>Sr<sub>x</sub>TiO<sub>3</sub> with lower Curie temperatures. Using strontium (Sr) as a tracer chemistry, transmission electron microscopy chemical mapping with energy-dispersive X-ray analysis indicates that there is a precipitation of a Ba<sub>1-</sub><sub>x</sub>Sr<sub>x</sub>TiO<sub>3</sub> mainly at grain/grain interfaces, while grain cores remain undoped. In addition, the difference in the interfacial Sr concentration, which is influenced by the applied uniaxial pressure direction, was clearly observed. This successful visualization of compositional distribution after CSP underlines the significant role of the pressure solution creep in densification process.</p>
    • Cold sintering process (CSP) has attracted great interest due to its extremely low processing temperatures, fast processing times, and simplicity to allow for the densification of ceramics and composites. Understanding the detailed mechanisms underlying low temperature densification is crucial to develop advanced materials and facilitate sustainable and cost-effective industrial implementation to come. Here, by taking BaTiO3 powder and Sr(OH)<sub>2</sub>·8H<sub>2</sub>O transient chemical flux as a model system, chemical transformation at solid/flux interfaces driving the dissolution-precipitation creep mechanism were investigated. We demonstrate that Sr(OH)<sub>2</sub>·8H<sub>2</sub>O acts both as a sintering flux and a solid solution doping additive, resulting in the formation of BaTiO<sub>3</sub> - Ba<sub>1-</sub><sub>x</sub>Sr<sub>x</sub>TiO<sub>3</sub> with lower Curie temperatures. Using strontium (Sr) as a tracer chemistry, transmission electron microscopy chemical mapping with energy-dispersive X-ray analysis indicates that there is a precipitation of a Ba<sub>1-</sub><sub>x</sub>Sr<sub>x</sub>TiO<sub>3</sub> mainly at grain/grain interfaces, while grain cores remain undoped. In addition, the difference in the interfacial Sr concentration, which is influenced by the applied uniaxial pressure direction, was clearly observed. This successful visualization of compositional distribution after CSP underlines the significant role of the pressure solution creep in densification process.</p>
  • Updated Description, Publication Date Show Changes
    Description
    • Cold sintering process (CSP) has attracted great interest due to its extremely low processing temperatures, fast processing times, and simplicity to allow for the densification of ceramics and composites. Understanding the detailed mechanisms underlying low temperature densification is crucial to develop advanced materials and facilitate sustainable and cost-effective industrial implementation to come. Here, by taking BaTiO3 powder and Sr(OH)<sub>2</sub>·8H<sub>2</sub>O transient chemical flux as a model system, chemical transformation at solid/flux interfaces driving the dissolution-precipitation creep mechanism were investigated. We demonstrate that Sr(OH)<sub>2</sub>·8H<sub>2</sub>O acts both as a sintering flux and a solid solution doping additive, resulting in the formation of BaTiO<sub>3</sub> - Ba<sub>1-</sub><sub>x</sub>Sr<sub>x</sub>TiO<sub>3</sub> with lower Curie temperatures. Using strontium (Sr) as a tracer chemistry, transmission electron microscopy chemical mapping with energy-dispersive X-ray analysis indicates that there is a precipitation of a Ba<sub>1-</sub><sub>x</sub>Sr<sub>x</sub>TiO<sub>3</sub> mainly at grain/grain interfaces, while grain cores remain undoped. In addition, the difference in the interfacial Sr concentration, which is influenced by the applied uniaxial pressure direction, was clearly observed. This successful visualization of compositional distribution after CSP underlines the significant role of the pressure solution creep in densification process.</p>
    • Cold sintering process (CSP) has attracted great interest due to its extremely low processing temperatures, fast processing times, and simplicity to allow for the densification of ceramics and composites. Understanding the detailed mechanisms underlying low temperature densification is crucial to develop advanced materials and facilitate sustainable and cost-effective industrial implementation to come. Here, by taking BaTiO3 powder and Sr(OH)<sub>2</sub>·8H<sub>2</sub>O transient chemical flux as a model system, chemical transformation at solid/flux interfaces driving the dissolution-precipitation creep mechanism were investigated. We demonstrate that Sr(OH)<sub>2</sub>·8H<sub>2</sub>O acts both as a sintering flux and a solid solution doping additive, resulting in the formation of BaTiO<sub>3</sub> - Ba(1-x)Sr<sub>x</sub>TiO<sub>3</sub> with lower Curie temperatures. Using strontium (Sr) as a tracer chemistry, transmission electron microscopy chemical mapping with energy-dispersive X-ray analysis indicates that there is a precipitation of a Ba(1-x)Sr<sub>x</sub>TiO<sub>3</sub> mainly at grain/grain interfaces, while grain cores remain undoped. In addition, the difference in the interfacial Sr concentration, which is influenced by the applied uniaxial pressure direction, was clearly observed. This successful visualization of compositional distribution after CSP underlines the significant role of the pressure solution creep in densification process.</p>
    Publication Date
    • 2021-01-01
    • 2020-09-07
  • Updated