X-Ray Absorption Spectroscopy of Strontium(II) Coordination

Area of Science:

• Materials Science
• Solid-State Chemistry
• Spectroscopy

Background:

• Understanding local atomic structure and disorder in strontium compounds is crucial for materials science.
• Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy is a powerful tool for probing local atomic environments.

Purpose of the Study:

• To quantify local thermal and static disorder in various strontium compounds using EXAFS.
• To characterize strontium coordination in different oxygen-ligated bonding environments.
• To analyze anharmonic vibrational disorder and its impact on EXAFS data.

Main Methods:

• Detailed EXAFS analyses of crystalline, hydrated, and precipitated strontium compounds and aqueous solutions.
• Quantification of local thermal and static disorder.
• Characterization of strontium coordination environments.
• Empirical parameterization of Debye-Waller factors.

Main Results:

• Anharmonic vibrational contributions were generally insignificant in solid strontium compounds.
• Aqueous strontium solutions showed significant anharmonic contributions and apparent distance decrease with temperature.
• Debye-Waller factors systematically increased with temperature and Sr-Z bond length.
• No significant local structure differences were observed between wet precipitated and dry strontianite (SrCO3).
• Strontium in Ca-zeolite substituted the Ca2 site, with backscattering from Al and Si observed.

Conclusions:

• Previous EXAFS studies on hydrated strontium may have underestimated distances and coordination numbers due to unaddressed phase-shift and amplitude contributions.
• Anharmonic disorder is primarily significant in aqueous strontium solutions.
• Debye-Waller factor parameterization provides insights into thermal and static disorder in strontium compounds.