Charge compensation assisted enhancement of photoluminescence in combustion derived Li⁺ co-doped cubic ZrO₂:Eu³⁺ nanophosphors

Abstract

Red light emitting cubic ZrEuO:Li (0-9 mol%) nanoparticles are synthesized by a low temperature, self-propagating solution combustion method using oxalyl di-hydrazide (ODH) as fuel. In this study, we report systematic investigation of the effect of lithium ion (Li) concentration on the structural properties and the photoluminescence of zirconia. With increasing lithium concentration, the crystallinity of the samples increases and the lattice strain decreases. The higher crystallinity is likely due to charge compensation achieved by replacing one Zr ion by a Eu and a Li ion. Scanning electron micrographs (SEM) reveal a mesoporous structure characteristic of combustion derived nanomaterials. Photoluminescence (PL) spectra show that the intensity of the red emission (606 nm) is highly dependent on Li ion concentration. Furthermore there is a promising enhancement in the associated lifetime. Upon Li doping, the PL intensity of the samples is found to increase by two fold compared to the undoped sample. Variation of PL intensity with Li concentration is attributed to the differences in probability of non-radiative recombination (relaxing). Intensity parameters (Ω, Ω) and radiative properties such as transition rates (A), branching ratios (β), stimulated emission cross-section (σ), gain bandwidth (σ × Δλ) and optical gain (σ × τ) are calculated using the Judd-Ofelt theory. The calculated values suggest that in optimally co-doped samples, in addition to improved crystallinity and charge compensation, the lowering of Eu site symmetry and the increase in the covalency of Eu-O bonding due to interstitial Li are responsible for the observed enhancement in PL intensity.

Effect of Bi3+ and Li+ co-doping on the luminescence properties of Zn2TiO4:Eu3+ nanophosphor for display applications

“…Emission transitions (colour purity, intensity and efficiency) of the RE ions are mainly affected by the kind of host material, interaction between the host and RE ions, proportion of the dopants concentration and dopant ions distribution and the transfer of energy from the host or sensitizer to the dopant ions. One of the major challenge for the wider use of phosphors, is the suitable inorganic host material, which supports efficient 4f-4f transitions of RE ions [2][3][4].…”

“…Trivalent RE ions (Eu 3+ , Tb 3+ , Sm 3+ , Er 3+ , Tm 3+ , Ho 3+ ) serve as an brilliant luminescent centres in inorganic phosphors owing to their appropriateness of excitation in the ultraviolet, visible and near infrared regions. Among, red emitting Eu 3+ activated phosphors plays a vital role in photonic device applications [4]. Zn 2 TiO 4 belongs to ZnO-TiO 2 family, an important host material among inorganic phosphors due its unique characters such as good thermal and chemical stability, low cost, non toxicity, abundance in nature, suitability for doping [5].…”

Solvothermal synthesis of columnar Gd2O2S:Eu3+ and a comparative study with columnar Gd2O3:Eu3+

“…The analysis based on the Judd-Ofelt parameters can be used to calculate the parity-forbidden electric-dipole radiative transition rates between different energy levels of rare-earth ions. 9,34,37 In this section, J-O parameters include A 01 , A 02 , A 04 , Ω 2 , and Ω 4 were calculated and other radiative properties were predicted based on these parameters.…”

Tailoring the photoluminescent properties of samarium and dysprosium codoped calcium zirconate perovskites for WLED applications

“…Along with these properties CaZrO 3 had been reported to have excellent mechanical and chemical properties . The long lasting phosphorescence CaZrO 3 and photo‐stimulated luminescence phenomenon of rare earth doped CaZrO 3 make it an excellent host material in the luminescent studies .…”