High-Pressure Thermodynamics of Solid Materials

High-pressure thermodynamics of solid materials examines how solids respond to extreme compression and temperature conditions, focusing on pressure–volume–temperature (P–V–T) relationships, phase stability, and transitions such as melting and solid–solid transformations. Central to this field are equations of state that relate thermodynamic variables, often informed by Grüneisen theory and first-principles calculations. Experimental platforms include diamond anvil cells and dynamic shock techniques, which enable in situ characterisation by X-ray diffraction, Raman spectroscopy and velocimetry. Advances in microstructural analysis after rapid quenching provide reliable melting criteria, while novel anvil designs push attainable pressures into the multi-megabar and terapascal regimes. Integration of static and dynamic data, alongside ab initio molecular dynamics, underpins models of planetary interiors, informs the synthesis of superhard and functional materials and refines pressure standards for energy and geoscience applications.

Research from Nature Portfolio

Innovative toroidal diamond anvil cells have been developed to extend static compression towards the terapascal range while preserving accurate measurement capabilities for metals and noble gases. This design overcomes strain-induced limits of conventional anvils, enabling precise determination of equations of state under unprecedented loads. Focused-ion-beam-machined single-crystal toroidal anvils with micrometre-scale culets have achieved pressures above 6 Mbar, stabilising gasket flow and facilitating studies relevant to planetary core conditions. Synchrotron X-ray diffraction in laser-heated diamond anvil cells, coupled with rapid quench techniques, has been applied to molybdenum. Analysis of post-melt microstructures up to 130 GPa reveals a steep melting curve and uncovers a high-temperature transition to textured bcc nanograins, offering a robust melting criterion and insight into defect-mediated phase behaviour.

High-Pressure Thermodynamics of Solid Materials publication trend

The graph below shows the total number of articles in high-pressure thermodynamics of solid materials across all publications each year (not limited to Nature Index journals).

Technical terms

Diamond anvil cell: A device that generates high static pressures by compressing a sample between two diamond tips.

Equation of state (EOS): A mathematical relationship linking pressure, volume and temperature of a material.

Grüneisen parameter: A dimensionless factor expressing the volume dependence of vibrational frequencies, used in thermal EOS models.

Laser-heating: A method to raise sample temperature inside a diamond anvil cell by focusing laser beams for in situ high-T measurements.

First-principles (ab initio) simulation: Computational techniques based on fundamental quantum mechanics to predict material properties without empirical parameters.

References

1. Melting Is Well-Known, but Is It Also Well-Understood?. Chemical Reviews (2023).
2. Toroidal diamond anvil cell for detailed measurements under extreme static pressures. Nature Communications (2018).
3. Single crystal toroidal diamond anvils for high pressure experiments beyond 5 megabar. Nature Communications (2018).
4. Microstructures define melting of molybdenum at high pressures. Nature Communications (2017).
5. Evaluation of thermodynamic equations of state across chemistry and structure in the materials project. npj Computational Materials (2018).
6. P–V–T Equation of State of Iridium Up to 80 GPa and 3100 K. Crystals (2021).