This work investigates the high-pressure structure of freestanding superconducting (Tc = 4.3\,K) boron doped diamond (BDD) and how it affects the electronic and vibrational properties using Raman spectroscopy and x-ray diffraction in the 0-30\,GPa range. High-pressure Raman scattering experiments revealed an abrupt change in the linear pressure coefficients and the grain boundary components undergo an irreversible phase change at 14\,GPa. We show that the blue shift in the pressure-dependent vibrational modes correlates with the negative pressure coefficient of Tc in BDD. The analysis of x-ray diffraction data determines the equation of state of the BDD film, revealing a high bulk modulus of B0=510±28\,GPa. The comparative analysis of high-pressure data clarified that the sp2 carbons in the grain boundaries transform into hexagonal diamond.
@article{arxiv.1709.07611,
title = {High-pressure behavior of superconducting boron-doped diamond},
author = {Mahmoud Abdel-Hafiez and Dinesh Kumar and R. Thiyagarajan and Q. Zhang and R. T. Howie and K. Sethupathi and O. Volkova and A. Vasiliev and W. Yang and H. K. Mao and M. S. Ramachandra Rao},
journal= {arXiv preprint arXiv:1709.07611},
year = {2017}
}