Effect of Ga³⁺Doping on the Photoluminescence Properties of Y₃Al_5-xGa_xO₁₂:Bi³⁺Phosphor

Abstract

The structural and luminescence characteristics of a sol-gel combustion synthesized Y 3 Al 5-x Ga x O 12 :Bi 3+ phosphor with different concentration of Ga 3+ were investigated. The Rietveld refinement analysis and luminescence studies indicated that increasing the concentration of the Ga ions changed the bond lengths and lattice parameters of the dodecahedron bonds and as a result the Bi 3+ experienced a different anionic environment in the YAG host. A systematic shift of the photoluminescence excitation and emission spectra to higher wavelengths was observed with an increase of the Ga 3+ concentration. The shift is attributed to the distortion of the host lattice as observed from the changing parameter and the covalency of the host with an increase of the Ga 3+ concentration. Despite the potential hazards of ultraviolet light causing sunburn, the ultraviolet (UV) spectrum offers many benefits in a wide range of technical manufacturing and industrial processing applications. Standard visible wavelength light emitting diodes (LEDs) have impacted today's illumination, signage and display markets. The advanced deployment of UV LEDs is now offering a wide range of advantages to a diverse number of applications, especially in the technical and industrial markets. For many applications such as medical light therapy, water sterilization, and polymer curing wavelengths shorter than 365 nm are needed. Luminescent efficient materials that are emitting in the 300-340 nm range are therefore in great demand. It is essential to search for highly efficient phosphors that have broadly tunable emissions and minimal excitation in the visible range. Trivalent bismuth cations (Bi 3+ ) with outer 6s 2 electronic configuration have been doped into a variety of host lattices, and they been shown to exhibit interesting tunable emission 1 over a broad range of wavelengths. The literature shows that the absorption bands of Bi 3+ are usually attributed to the 1 S 0 -1 P 1 and the 1 S 0 -3 P 1 transitions, which are both allowed due to spin-orbit coupling. The energy level of the 3 P 1 excited state is lower than that of the 1 P 1 excited state, this leads to the emission of the Bi 3+ ions to be a single broad band from the 3 P 1 -1 S 0 transition. 1 The luminescence properties of Bi 3+ ions are strongly dependent on the conditions of the surrounding environment of the host lattice 2 such as the covalency, coordination number, site symmetry and the space group. This allows the luminescence of Bi 3+ ions to change from ultraviolet to red by changing the host lattice. 4 emission wavelengths ranging from UV to near infrared. The sol-gel combustion method is a novel method that uses a unique combination of the chemical sol-gel and combustion process. The modern research emphasizes the advantages of combustion synthesis because of its cost-effectiveness and environmental friendliness.5 Although combustion synthesis is considered one of the easy methods to synthesize nano-materials, yet a lot of improvement is still required especially in terms...

Luminescence Spectroscopy and Origin of Luminescence Centers in Bi-Doped Materials

“…This could mean that the triplet RES of Bi 3+ is located closer to the bottom of CB in Lu In Ref. [200], the effect of Ga 3+ doping on the photoluminescence properties of Y 3 Al 5-x Ga x O 12 :Bi was studied. It was shown that the incorporation of the Ga 3+ ions results in a strong reduction of the band gap edge (by 1 eV from Y 3 Al 5 O 12 :Bi to Y 3 Ga 5 O 12 :Bi).…”

Enhancing the Relative Sensitivity of V5+, V4+ and V3+ Based Luminescent Thermometer by the Optimization of the Stoichiometry of Y3Al5−xGaxO12 Nanocrystals

“…However, it was found that Ga 3+ ions preferentially occupy four-fold coordinated sites of Al 3+ rather than the octahedral counterpart. This phenomenon can be explained based on the stronger covalency of Ga 3+ -O 2− bonds with respect to the Al 3+ -O 2− ones and the lowering of repulsive forces between cations, providing stabilization of the crystal structure [31,32]. On the other hand, the slight shift of the XRD peaks with respect to the reference pattern arises from the implementation of V ions into Y 3 Al 5−x Ga x O 12 lattice.…”

Comparison of Y2O3:Bi3+ phosphor thin films fabricated by the spin coating and radio frequency magnetron techniques

“…The ground state of Bi 3 þ ions, with a 6s6s configuration, is 1 S 0 , whereas the excited state, with a 6s6p configuration, is the triplet state ( 3 P 0 , 3 P 1 , 3 P 2 ). The 1 P 1 singlet state has four energy levels that increase in energy [31]. The excitation and emission bands were assigned to the 1 S 0 -3 P 1 and 3 P 1 -1 S 0 transitions at room temperature [26].…”