Abstract
Neighborite perovskite (NaMgF3) is a close analogue to Mg or Ca silicate perovskite. It experiences a second-order phase transition at high T that may have a significant effect on the acoustic velocities. Here we report the measurement of elastic wave velocities of neighborite perovskite using the multi-anvil high-pressure apparatus located in beamline 6-BM-B at the Advanced Photon Source. We use the newly installed ultrasonic interferometry equipment using pulse-echo-overlap method coupled with the D-DIA device. X- radiographic imaging is used to measure sample length at high P-T. X-ray diffraction spectrum is used to determine the pressure and sample conditions. Precise measurements of P and S wave velocities are at 60 and 35 MHz respectively and are nearly simultaneous. We use a double reflector method to enable measurement of elastic wave velocities of cold-pressed polycrystalline sample that is sintered in situ at high P-T. Experiments were carried out up to 3 GPa and 1000 °C. Our results indicated that MHz ultrasonic acoustic velocities experience a significant minimum at the phase transition, with the bulk modulus being more affected than the shear modulus. The shear modulus of the cubic phase appears unchanged from those of the orthorhombic phase, while the bulk modulus increases in transforming into the cubic phase.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.