Thermal expansion behavior in the solid solution series BaMg2−xCoxSi2O7 (0≤x≤2), studied by dilatometry and in situ high-temperature X-ray diffraction

Thermal properties of (Gd0.6Sr0.4)0.99Fe1-xCoxO3-δ cathodes for intermediate temperature solid oxide fuel cells

“…Compared to other thermal properties, thermal expansion is an essential property for use of materials in SOFC devices since various crystalline phases coexist during their operation. Thermal expansion characterizes the directional dependence of the crystal structure by measuring the linear thermal expansion ∆ ⁄ and the thermal expansion coefficient (TEC) [30]. The TEC is an important thermal property, as any thermal expansion mismatch of the cell components is detrimental to the cyclic stability of SOFCs.…”

New Family of Materials with Negative Coefficients of Thermal Expansion: The Effect of MgO, CoO, MnO, NiO, or CuO on the Phase Stability and Thermal Expansion of Solid Solution Phases Derived from BaZn2Si2O7

“…Glasses, ceramics, and glass ceramics based on silicates with high concentrations of alkaline earth ions normally exhibit very high CTEs, caused by high CTE phases such as barium silicates. − In the case of BaZn 2 Si 2 O 7 , two phases are reported: an orthorhombic high temperature phase (HT-phase) and a monoclinic low temperature phase (LT-phase) with a phase transition temperature at around 280 °C . Both phases exhibit strongly different thermal expansion characteristics: i.e., BaZn 2 Si 2 O 7 shows high thermal expansion below 280 °C, and above this temperature, low and partly negative thermal expansion occurs .…”

“…The thermal expansion is then highly positive in the entire temperature range until the phase transition temperature is reached. Depending on the particular chemical composition, the coefficient of thermal expansion can be higher than 15 × 10 –6 K –1 and the phase transition temperature can be shifted to temperatures above 1000 °C . The increase in volume, which correlates with the phase transition, decreases if ZnO is partially or fully replaced by other divalent ions with similar ionic radii. , It should be mentioned that the phase BaZn 2 Si 2 O 7 and also solid solutions with the compositions BaZn 2– x M x Si 2 O 7 (M = Co, Ni) have already been crystallized from typical sealing glasses by an appropriate thermal treatment. , The as prepared glasses can be utilized as crystallizing seals with high CTEs for high-temperature applications.…”