TY - JOUR
T1 - Thermochemistry of (Ca xSr 1-x) TiO 3, (Ba xSr 1-x) TiO 3, and (Ba xCa 1-x) TiO 3 perovskite solid solutions
AU - Navi, Nissim U.
AU - Shneck, Roni Z.
AU - Shvareva, Tatiana Y.
AU - Kimmel, Giora
AU - Zabicky, Jacob
AU - Mintz, Moshe H.
AU - Navrotsky, Alexandra
PY - 2012/5/1
Y1 - 2012/5/1
N2 - High-temperature solution calorimetry in molten 3Na 2O• 4MoO 3 solvent at 975 K is used to measure the enthalpy of mixing of (Ca xSr 1-x)TiO 3 and (Ba xSr 1-x)TiO 3 solid solutions. Both solid solutions show positive enthalpy of mixing, however, the (Ba xSr 1-x) TiO 3 shows less deviation from ideality, with interaction parameter λ = 8.5 ± 3.8 kJ/mol, than (Ca xSr 1-x) TiO 3 with interaction parameter λ = 25.3 ± 2.0 kJ/mol. The smaller interaction parameter of the (Ba xSr 1-x) TiO 3 system is attributed to the volume mismatch of the end-members. The larger interaction parameter of (Ca xSr 1-x)TiO 3 may be related to larger ionic radius difference of Ca and Sr and may also reflect the additional energy needed to overcome the lattice distortion of the orthorhombic CaTiO 3 to incorporate it into the cubic perovskite SrTiO 3. (Ba xCa 1-x)TiO 3 has a large positive heat of mixing and limited solid solubility as derived from its phase diagram. This study indicates the tendency of SrTiO 3 and BaTiO 3 to separate from a CaTiO 3 host matrix, which may be significant in perovskite-bearing nuclear waste ceramics incorporating 90Sr and 137Ba.
AB - High-temperature solution calorimetry in molten 3Na 2O• 4MoO 3 solvent at 975 K is used to measure the enthalpy of mixing of (Ca xSr 1-x)TiO 3 and (Ba xSr 1-x)TiO 3 solid solutions. Both solid solutions show positive enthalpy of mixing, however, the (Ba xSr 1-x) TiO 3 shows less deviation from ideality, with interaction parameter λ = 8.5 ± 3.8 kJ/mol, than (Ca xSr 1-x) TiO 3 with interaction parameter λ = 25.3 ± 2.0 kJ/mol. The smaller interaction parameter of the (Ba xSr 1-x) TiO 3 system is attributed to the volume mismatch of the end-members. The larger interaction parameter of (Ca xSr 1-x)TiO 3 may be related to larger ionic radius difference of Ca and Sr and may also reflect the additional energy needed to overcome the lattice distortion of the orthorhombic CaTiO 3 to incorporate it into the cubic perovskite SrTiO 3. (Ba xCa 1-x)TiO 3 has a large positive heat of mixing and limited solid solubility as derived from its phase diagram. This study indicates the tendency of SrTiO 3 and BaTiO 3 to separate from a CaTiO 3 host matrix, which may be significant in perovskite-bearing nuclear waste ceramics incorporating 90Sr and 137Ba.
UR - http://www.scopus.com/inward/record.url?scp=84861100201&partnerID=8YFLogxK
U2 - https://doi.org/10.1111/j.1551-2916.2012.05137.x
DO - https://doi.org/10.1111/j.1551-2916.2012.05137.x
M3 - Article
SN - 0002-7820
VL - 95
SP - 1717
EP - 1726
JO - Journal of the American Ceramic Society
JF - Journal of the American Ceramic Society
IS - 5
ER -