TY - JOUR
T1 - The strange case of enhancing the resistivity by extended sintering time in (Bi0.5Na0.5)TiO3–BaTiO3 solid solution
AU - Fan, Zhongming
AU - Randall, Clive A.
N1 - Publisher Copyright:
© 2023 Elsevier Ltd
PY - 2023/12/1
Y1 - 2023/12/1
N2 - With the presence of volatile elements in the composition of a ceramic material, longer sintering time presumably creates more vacancies. In the case of (Bi0.5Na0.5)TiO3–BaTiO3 lead-free piezoelectric ceramics and when batched and calcined with a Bi2O3 deficient stoichiometry, there can be a surprising increase in resistivity with increasing sintering time. It is deduced that the extended sintering time reduces the concentration of bismuth vacancies (and the ionically compensating oxygen vacancies). This is also associated with a decrease of depolarization temperature, Td, and possibly a change in dielectric polarization phenomena from normal to relaxor ferroelectric. These observations do not occur in pure (Bi0.5Na0.5)TiO3, suggesting that they are actually facilitated by the Ba2+ content in the solid solution BNT−BT. Microstructural observations indicate the formation of BaTi2O5 secondary phase which considerably grows as sintering goes on. With more Ti4+ being incorporated to the secondary phase, the stoichiometry of the solid solution can be restored, so is the resistivity and the observed trends in decreased Td.
AB - With the presence of volatile elements in the composition of a ceramic material, longer sintering time presumably creates more vacancies. In the case of (Bi0.5Na0.5)TiO3–BaTiO3 lead-free piezoelectric ceramics and when batched and calcined with a Bi2O3 deficient stoichiometry, there can be a surprising increase in resistivity with increasing sintering time. It is deduced that the extended sintering time reduces the concentration of bismuth vacancies (and the ionically compensating oxygen vacancies). This is also associated with a decrease of depolarization temperature, Td, and possibly a change in dielectric polarization phenomena from normal to relaxor ferroelectric. These observations do not occur in pure (Bi0.5Na0.5)TiO3, suggesting that they are actually facilitated by the Ba2+ content in the solid solution BNT−BT. Microstructural observations indicate the formation of BaTi2O5 secondary phase which considerably grows as sintering goes on. With more Ti4+ being incorporated to the secondary phase, the stoichiometry of the solid solution can be restored, so is the resistivity and the observed trends in decreased Td.
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U2 - 10.1016/j.ssc.2023.115355
DO - 10.1016/j.ssc.2023.115355
M3 - Article
AN - SCOPUS:85174705730
SN - 0038-1098
VL - 375
JO - Solid State Communications
JF - Solid State Communications
M1 - 115355
ER -