Structural Features and Defect Equilibrium in Cubic PrBa_1-SrFe₂O_6-.

Area of Science:

• Materials Science
• Solid State Chemistry
• Crystallography

Background:

• Perovskite-type oxides are crucial for various applications due to their tunable properties.
• Understanding defect structures and oxygen non-stoichiometry is key to optimizing their performance.
• The PrBa$_{1-x}$Sr$_x$Fe$_2$O$_{6-δ}$ system presents a platform to study these phenomena.

Purpose of the Study:

• To investigate the structure, oxygen non-stoichiometry, and defect equilibrium in PrBa$_{1-x}$Sr$_x$Fe$_2$O$_{6-δ}$ (x = 0, 0.25, 0.50).
• To elucidate the influence of oxygen deficiency and strontium substitution on defect ordering.
• To model the defect equilibrium considering various reaction pathways.

Main Methods:

• Synthesis of perovskite-type oxides at 1350 °C.
• X-ray diffraction and electron diffraction for structural analysis.
• Coulometric titration for oxygen content measurement as a function of oxygen partial pressure and temperature.
• Modeling of defect equilibrium.

Main Results:

• Formation of a cubic structure (S.G. Pm3¯m) with evidence of short-range order and incommensurate modulation.
• Oxygen deficiency promotes ordering, while strontium substitution suppresses it.
• Coulometric titration data enabled defect equilibrium modeling, indicating oxygen vacancy ordering.
• Increased strontium content suppressed oxygen vacancy ordering and increased p-type carrier concentration.

Conclusions:

• The PrBa$_{1-x}$Sr$_x$Fe$_2$O$_{6-δ}$ system exhibits complex defect ordering influenced by composition.
• Oxygen vacancy ordering plays a significant role in the defect equilibrium of these oxides.
• Strontium substitution impacts defect behavior and electronic properties, offering avenues for material design.