TY - JOUR
T1 - In situ doping of BaTiO3 and visualization of pressure solution in flux-assisted cold sintering
AU - Sada, Takao
AU - Fan, Zhongming
AU - Ndayishimiye, Arnaud
AU - Tsuji, Kosuke
AU - Bang, Sun Hwi
AU - Fujioka, Yoshihiro
AU - Randall, Clive A.
N1 - Funding Information:
T.S thanks the Kyocera Corporation for Funding his Fellowship enabling his time as a visiting scientist at Penn State University. A.N, Z.F and CAR were partially supported from the AFOSR grant (grant no. FA9550‐19‐1‐0372). We also wish to thank the staffs of the MCL for aid in sample preparation, and in maintaining electrical measurement facilities. The authors thank Joanne Aller for helping in proof reading and formatting this publication.
Publisher Copyright:
© 2020 The American Ceramic Society
PY - 2021/1
Y1 - 2021/1
N2 - 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 - Ba1-xSrxTiO3 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 Ba1-xSrxTiO3 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.
AB - 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 - Ba1-xSrxTiO3 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 Ba1-xSrxTiO3 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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U2 - 10.1111/jace.17461
DO - 10.1111/jace.17461
M3 - Article
AN - SCOPUS:85091011470
SN - 0002-7820
VL - 104
SP - 96
EP - 104
JO - Journal of the American Ceramic Society
JF - Journal of the American Ceramic Society
IS - 1
ER -