Titanium boride equation of state determined by in-situ X-ray diffraction

Area of Science:

• Materials Science
• Geophysics
• High-Pressure Physics

Background:

• Titanium diboride (TiB2) is a crucial material in various industrial applications.
• Understanding its behavior under extreme conditions is vital for its effective utilization.
• Previous studies have explored its properties, but comprehensive equation of state data across a wide pressure-temperature range was lacking.

Purpose of the Study:

• To experimentally determine the equation of state (EOS) of titanium diboride (TiB2).
• To investigate the phase stability of TiB2 under high pressures and temperatures.
• To derive fundamental thermodynamic parameters such as the isothermal bulk modulus and its pressure derivative.

Main Methods:

• In situ X-ray diffraction experiments were conducted using diamond anvil cells (DAC) and multianvil high-pressure apparatus.
• Pressure-volume-temperature (P-V-T) data were collected up to 111 GPa at room temperature (DAC) and up to 15 GPa and 1300 K (multianvil).
• The Vinet equation of state was employed to fit the experimental data.

Main Results:

• No phase transitions were observed in TiB2 within the investigated experimental conditions.
• The isothermal bulk modulus (B) was determined to be 256.7 GPa.
• The pressure derivative of the bulk modulus (B') was found to be 3.83.
• Thermal expansion coefficient (α) and a related parameter were quantified.

Conclusions:

• Titanium diboride exhibits remarkable phase stability across a broad range of high pressures and temperatures.
• The derived equation of state parameters provide critical data for modeling TiB2 behavior in extreme environments.
• This research enhances the understanding of refractory materials under geophysically relevant conditions.