X-ray diffraction in the pulsed laser heated diamond anvil cell.

Area of Science:

• High-pressure physics
• Materials science
• Synchrotron science

Background:

• In situ X-ray diffraction is crucial for studying materials under extreme conditions.
• Previous methods for laser heating in diamond anvil cells had limitations in temperature control and uniformity.

Purpose of the Study:

• To develop a novel pulsed laser heating technique for in situ X-ray diffraction.
• To achieve precise temperature control and uniformity in microsecond timescales at high pressures.
• To enable accurate measurements of melting curves, phase transitions, and thermal equations of state.

Main Methods:

• Utilized a pulsed fiber laser (1064-1075 nm, 2-10 kHz repetition rate, 1-100 μs pulse width) synchronized with a gated X-ray detector (Pilatus).
• Performed in situ X-ray synchrotron diffraction measurements on samples within a diamond anvil cell up to 60 GPa.
• Employed time-resolved radiometric temperature measurements and finite element calculations.

Main Results:

• Demonstrated microsecond timescale temperature monitoring up to 3000 K with excellent axial and radial temperature uniformity.
• Showcased the ability to fine-tune maximum sample temperature by adjusting laser pulse width.
• Validated the technique through comparison with finite element calculations.

Conclusions:

• The developed pulsed laser heating technique offers a convenient and accurate method for studying materials under extreme conditions.
• This technique facilitates precise measurements of melting curves, phase changes, and thermal equations of state.
• The fine temperature control minimizes chemical reactivity and diffusion, enhancing data reliability.