SBN60, strontium-barium niobate at 100 K

Area of Science:

• Materials Science
• Solid State Chemistry
• Crystallography

Background:

• Strontium barium niobates (Sr x Ba 1-x Nb 2 O 6) are a class of materials known for their ferroelectric properties below a specific Curie temperature (T c).
• The compound Sr 0.6 Ba 0.4 Nb 2 O 6 (SBN60) is investigated, with a reported Curie temperature of 346±0.5 K, confirming its ferroelectric phase at 100 K.

Purpose of the Study:

• To elucidate the crystallographic structure and cation/anion site occupancy of strontium barium niobate (Sr 0.6 Ba 0.4 Nb 2 O 6).
• To understand the disorder in ion distribution within the vacancy tunnels of this ferroelectric material.

Main Methods:

• Crystallographic analysis to determine the atomic positions and occupancies.
• Detailed examination of the packing along the z-axis and the nature of vacancy tunnels (pentagonal, square, triangular).

Main Results:

• Sr 2+ ions partially occupy two distinct sites within pentagonal and square tunnels, with specific positional and symmetry relationships.
• Significant disorder is observed, particularly for Ba 2+ and Sr 2+ ions in the pentagonal tunnels, and for oxygen anions in both general and mirror plane positions.
• Specific site occupancies and relative disorder ratios (e.g., 0.43:0.41:0.16 for Ba/Sr, 0.52:0.48 and 0.64:0.36 for O) were quantified.

Conclusions:

• The ferroelectric properties of Sr 0.6 Ba 0.4 Nb 2 O 6 are intrinsically linked to the complex structural arrangement and significant ionic disorder.
• Understanding this disorder is crucial for tailoring the properties of strontium barium niobates for potential applications in electronic devices.