By varying ratios, red P (Sigma-Aldrich, ≥97.0%),
tin (Sigma-Aldrich,
99%, trace metal basis), and tin(IV) iodide (Sigma-Aldrich, 99.999%,
trace metals) were loaded in a glass ampule that was vacuum-sealed
using an oxygen burner. The glass ampule was thereafter placed in
a flange-fitted stainless-steel tube. The glass ampule in the stainless
tube was then heated to a specific temperature and retained at the
temperature for some period, and subsequently steadily cooled to room
temperature. To optimize the crystal formation time and the safest
crystal formation conditions, different patterns of heating and cooling
procedures were employed on glass ampules with varying dimensions.
The prepared BP crystals were characterized by XRD, Raman spectroscopy,
XPS, and scanning electron microscopy. The XRD measurements were conducted
at room temperature using a RINT 2200VF instrument. The Raman measurements
of BP were performed using a Nicolet Almega XR Raman spectrometer
with a 532 nm laser. The XPS data were obtained using an AXIS-NOVA
XPS system using an Al Kα X-ray source. The incident and emission
angles were 60 and 0° to the surface normal, respectively. The
analyzer pass energies for the wide range and high-resolution measurements
were set to 160 and 20 meV, respectively.
tin (Sigma-Aldrich,
99%, trace metal basis), and tin(IV) iodide (Sigma-Aldrich, 99.999%,
trace metals) were loaded in a glass ampule that was vacuum-sealed
using an oxygen burner. The glass ampule was thereafter placed in
a flange-fitted stainless-steel tube. The glass ampule in the stainless
tube was then heated to a specific temperature and retained at the
temperature for some period, and subsequently steadily cooled to room
temperature. To optimize the crystal formation time and the safest
crystal formation conditions, different patterns of heating and cooling
procedures were employed on glass ampules with varying dimensions.
The prepared BP crystals were characterized by XRD, Raman spectroscopy,
XPS, and scanning electron microscopy. The XRD measurements were conducted
at room temperature using a RINT 2200VF instrument. The Raman measurements
of BP were performed using a Nicolet Almega XR Raman spectrometer
with a 532 nm laser. The XPS data were obtained using an AXIS-NOVA
XPS system using an Al Kα X-ray source. The incident and emission
angles were 60 and 0° to the surface normal, respectively. The
analyzer pass energies for the wide range and high-resolution measurements
were set to 160 and 20 meV, respectively.