Abstract
Abstract
The structural evolution of black arsenic-phosphorous (b-As
x
P1–x
) alloys with varying arsenic concentrations was investigated under hydrostatic pressure using in situ Raman spectroscopy. High-pressure experiments were conducted using a diamond anvil cell, which revealed pressure-induced shifts in vibrational modes associated with P–P bonds (A
1
g
, A
2
g
,
B
2
g
), As–As bonds (A
1
g
, A
2
g
,
B
2
g
), and As–P bonds in b-As
x
P1–x
alloys. Two distinct pressure regimes were observed. In the first regime (region I), all vibrational modes exhibited a monotonic upshift, indicating phonon hardening due to hydrostatic pressure. In the second regime (region II), As0.4P0.6 and As0.6P0.4 alloys displayed a linear blueshift (or negligible change in some modes) at a reduced rate, suggesting local structural reorganization with less compression on the bonds. Notably, the alloy with the highest As concentration, As0.8P0.2, exhibited anomalous behavior in the second pressure regime, with a downward shift observed in all As–As and As–P Raman modes (and some P–P modes). Interestingly, the emergence of new peaks corresponding to the Eg
mode and A
1g
mode of the gray-As phase was observed in this pressure range, indicating compressive strain-induced structural changes. The anomalous change in region II confirms the formation of a new local structure, characterized by elongation of the P–P, As–As, and As–P bonds along the zigzag direction within the b-As
x
P1–x
phase, possibly near the grain boundary. Additionally, a gray-As phase undergoes compressive structural changes. This study underscores the significance of pressure in inducing structural transformations and exploring novel phases in two-dimensional materials, including b-As
x
P1–x
alloys.
Funder
the U.S. Department of Energy, Office of Science, Basic Energy Sciences
Subject
Electrical and Electronic Engineering,Mechanical Engineering,Mechanics of Materials,General Materials Science,General Chemistry,Bioengineering