Blue or red photoluminescence emission in α‐Bi₂O₃ needles: Effect of synthesis method

Abstract

Monoclinic bismuth oxide (α-Bi O ) has attractive optical properties and, therefore, its photoluminescence (PL) behavior has been increasingly explored. Besides this fact, the influence of synthesis methods on PL properties of α-Bi O still requires research. This paper describes the influence of precipitation (PPT) and microwave-assisted hydrothermal (MAH) methods on PL properties of acicular α-Bi O microcrystals. The synthesis method promoted structural modifications on α-Bi O , in particular PPT increased the density of oxygen vacancies significantly. As a result, the PL properties of samples were different depending on the method of synthesis. PPT samples presented their maximum PL emission at 1.91 eV (red), while MAH samples had their maximum at 2.61 eV (blue). These results indicate the possibility of controlling PL properties of α-Bi O by simply choosing the adequate synthesis method.

Structural and Enhanced Optical Properties of Stabilized γ‒Bi2O3 Nanoparticles: Effect of Oxygen Ion Vacancies

“…The emission from Bi 2+ is attributed to 2 P 3/2 (1) → 2 P 1/2 transitions, giving rise to luminescence spectra that peak in the wavelength range 591–637 nm under UV excitation [ 48 , 49 ]. Recently, the low-energy red-band emission has been attributed to crystal defects or defect levels associated with V O or bismuth interstitials formed during the growth process [ 50 , 51 ]. Figure 4 a presents the RT PL spectra (open dots) of γ–Bi 2 O 3 showing a strong and broad emission from ~350 to 900 nm centered at around 700 nm.…”

“…Kumari et al also reported emission maxima between 660 and 770 nm from composite α/β–Bi 2 O 3 attributed to defect/impurity states induced by oxygen vacancies present in the nanostructures [ 47 ]. Recently, a schematic study carried out by Schmidt et al reported an enhanced red-band emission from a sample with a high density of V O in α–Bi 2 O 3 [ 51 ]. Wu et al affirmed that the higher PL emission intensity of red-band emission means a higher V O density.…”

Influences of Substrate Temperatures and Oxygen Partial Pressures on the Crystal Structure, Morphology and Luminescence Properties of Pulsed Laser Deposited Bi2O3:Ho3+ Thin Films

“…PL is also a very useful technique to investigate the structure, the electronic band transitions and the intrinsic and extrinsic defects of these deposited materials [12], and has extensively been used to study the optical variations of α-Bi 2 O 3 which can potentially be used in numerous applications [12][13][14]. Li et al [15] reported the layer-by-layer assembly preparation of thin-film Bi 2 O 3 .…”