  Gold selenide (AuSe) is a multilayer compound yet to be thoroughly studied.
The colloidal synthesis and characterization of gold selenide nanoparticles are
described, emphasizing the effect of different gold-to-selenium precursor
ratios and temperatures on the crystal structure and form. The structural
characterization is done using an X-ray diffraction pattern. The coexistence of
the {\alpha}- and {\beta}-AuSe phases is observed in all synthesized samples.
The morphologies of the mainly {\alpha}-AuSe sample are nanobelts, whereas the
primarily {\beta}-AuSe phase sample has a nanoplate-like structure, according
to the TEM and SEM data. All of the samples had Raman vibrational modes with
mixed phases. The effect of high pressure on as-prepared AuSe samples has been
studied in this work. The introduction of external pressure and temperature
allows both phases to transition. Pressure lowers the existence of other phase
modes, and the corresponding dominating sample modes are entirely significant
in our sample. The phase transition pressure was observed using Raman
scattering. Our findings show that 2D AuSe has a lot of promise for
multifunctional applications, encouraging more research on these systems.
