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Pressure-Induced Stabilization of Terbium(IV) in CsTb(CrO4)2 Characterized by X-ray Absorption Spectroscopy
Tyler W Hines1, Lucia Amidani2,3, Nicholas B Beck1
1Department of Chemistry and Nuclear Science & Engineering Center, Colorado School of Mines, Golden, Colorado 80401, United States.
Journal of the American Chemical Society
|June 16, 2026
Summary
High pressure stabilizes the tetravalent terbium (Tb4+) state in CsTb(CrO4)2 and CsDy(CrO4)2 crystals. This pressure-induced transformation, observed via X-ray diffraction and spectroscopy, expands the known chemistry of terbium.
Area of Science:
- Materials Science
- Solid-State Chemistry
- High-Pressure Physics
Background:
- Lanthanide compounds exhibit diverse properties influenced by oxidation states.
- Investigating high-pressure effects on rare-earth materials is crucial for understanding their electronic and structural behavior.
- Terbium's tetravalent state (Tb4+) is rare and challenging to stabilize under ambient conditions.
Purpose of the Study:
- To investigate the structural and electronic changes in CsTb(CrO4)2 and CsDy(CrO4)2 under gigapascal pressures.
- To explore the possibility of stabilizing the tetravalent terbium state (Tb4+) using high pressure.
- To characterize the pressure-induced phase transitions and spectral changes in these materials.
Main Methods:
- Single-crystal X-ray diffraction (SCXRD) for structural analysis.
- High-pressure UV-vis-NIR spectroscopy to observe electronic transitions.
- Raman spectroscopy to probe vibrational modes.
- Terbium L3-edge high-energy-resolution fluorescence-detected X-ray absorption near-edge structure (HERFD-XANES) for detailed electronic state analysis.
Main Results:
- UV-vis-NIR spectra showed significant band broadening and a color change from yellow to dark red/black under pressure.
- High-energy-resolution fluorescence-detected X-ray absorption near-edge structure (HERFD-XANES) provided clear evidence for the stabilization of Tb4+ starting at 19.62 GPa.
- Single-crystal X-ray diffraction confirmed structural changes under high pressure.
Conclusions:
- High pressure effectively stabilizes the tetravalent terbium (Tb4+) state in CsTb(CrO4)2.
- This study presents the first instance of pressure-induced stabilization of Tb4+.
- The findings expand the understanding of terbium chemistry and high-pressure effects on lanthanide materials.
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