Structural changes in Rochelle salt on phase transitions revisited in a multi-temperature single-crystal X-ray...

Area of Science:

• Solid-state chemistry
• Crystallography
• Materials science

Background:

• Rochelle salt exhibits complex phase transitions between paraelectric and ferroelectric states.
• Understanding these transitions is crucial for materials science applications.

Purpose of the Study:

• To re-examine phase transitions in Rochelle salt using multi-temperature single-crystal X-ray diffraction.
• To compare structural models and analyze atomic displacement parameters.

Main Methods:

• Single-crystal X-ray diffraction performed across a temperature range (100–308 K).
• Structure refinement using harmonic (with/without disorder) and anharmonic models.
• Analysis of anisotropic displacement parameters (ADPs) and Ueq.

Main Results:

• Dynamic disorder of K1 atoms in the low-temperature paraelectric phase was identified.
• The high-temperature and low-temperature paraelectric phases share structural similarities.
• First-time comparison of structures across multiple temperatures for both PE phases from the same crystal.

Conclusions:

• The high-temperature and low-temperature paraelectric phases of Rochelle salt are likely the same phase at different temperatures.
• This challenges previous assumptions of distinct phases.
• The dynamic disorder of K1 atoms is a key feature of the low-temperature PE phase.