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Updated: Jan 6, 2026
12:30
High-pressure, High-temperature Deformation Experiment Using the New Generation Griggs-type Apparatus
Published on: April 3, 2018
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Do SnI4 molecules deform on heating and pressurization in the low-pressure crystalline phase?
Hiroki Naruta1, Kazuhiro Fuchizaki1, Daisuke Wakabayashi2
1Department of Physics, Ehime University, Matsuyama 790-8577, Japan.
Summary
Tin(IV) iodide (SnI4) molecules maintain their symmetry in crystalline phases, even under high pressure and temperature. This molecular incompressibility significantly exceeds that of the crystal lattice.
Area of Science:
- Solid-state chemistry
- Materials science
- High-pressure physics
Background:
- The SnI4 molecule exhibits a symmetry change from Td to a lower symmetry upon transitioning from liquid to liquid states.
- Investigating molecular symmetry changes within crystalline phases is crucial, especially when crystalline symmetry is not violated.
Purpose of the Study:
- To investigate potential symmetry changes in SnI4 molecules within the crystalline phase under varying pressures and temperatures.
- To understand the structural behavior of SnI4 during phase transitions and its implications for molecular and lattice incompressibility.
Main Methods:
- Extended X-ray Absorption Fine Structure (EXAFS) measurements were performed on crystalline SnI4.
- Experiments were conducted across a range of high pressures and temperatures, including near melting points and in high-pressure crystalline phases.
Main Results:
- No clear evidence of molecular symmetry change was observed in the crystalline phase, even near the melting curve.
- Coordination number around the Sn atom remained constant within the examined temperature and pressure ranges.
- The SnI4 molecule was found to be over an order of magnitude more incompressible than the surrounding lattice.
Conclusions:
- SnI4 molecules retain their symmetry in crystalline phases under investigated conditions.
- A consistent structural model for phase transformation in SnI4 is proposed.
- The study quantifies the significant incompressibility of the SnI4 molecule relative to its lattice.
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