Introduction

Luminescent materials are the inorganic and organic materials which are the combination of host compound and dopant materials [1]. These materials produce light energy under the excitation of external source like light or electricity [1]. These materials are referred as phosphors. These materials are highly used in LEDs, lasers, displays, pharmaceuticals etc [2][3]. The rare-earth materials like Ce³⁺ and Eu²⁺ are very sensitive to around crystal field environment and produce broad emission under the excitation of particular wavelength [4][5]. The emission of Eu²⁺ doped inorganic phosphors is generally due to the parity allowed 4f-5d transitions. Also, persistent or broad emission inorganic phosphors always have strong quantum yield value and high storage capacity [6]. Thus, these materials show prominent applications in the field of energy storage.

Terraschke et al. [6] provide a detail review based on 321 research paper and suggest that Eu²⁺ ions have electron transition between 4f⁶ to 4f⁷ energy states which are strongly influenced by host lattice. Thus, Eu²⁺ based inorganic phosphors open for many applied applications. Wang et al. [7] studied LaSrAl₂O₃:Eu²⁺ inorganic phosphors and suggests the phosphor can be a good material for optical storage device. Li et al. [8] synthesized SrAl₂O₄:Eu²⁺, Dy³⁺ inorganic phosphors and study the effect of Pb²⁺ ions on them. The work suggests that the material can be a promising material for information storage applications.

In this work, we synthesized MgSiO₃:Eu²⁺ compound using modified solid state reaction method. The excitation and emission spectra for the sample have been studied. Further, the theoretical emission spectra are stimulated using Electronic-Vibrational Interacting parameters.

Method and Synthesis

All starting reactants for the preparation of MgSiO₃:Eu²⁺ inorganic phosphors were analytical reagent grade. The inorganic phosphor was prepared using modified solid-state reaction method. The phosphor was obtained using magnesium carbonate (MgCO₃), silicic acid (SiO₂.9H₂O) and Eu₂O₃ in HNO₃ as raw materials. All stoichiometrically weighed out materials were mixed together and crushed for

phono line position [11][12]. The parameters ultimately used to stimulate emission parameter using following equation [13] –

Here, m is the effective number of phonons occurred during emission transition. E₀ is the zero-phonon energy. S is Huang-Rhys coupling constant. ħ, w, k, T, and E are Plank’s constant, angular velocity, Boltzmann constant, temperature, and energy at a given wavelength respectively. The stimulated emission peak is shown in Figure 2.

Figure 2: Experimental and stimulated emission spectra for MgSiO₃:Eu²⁺ inorganic phosphor

The estimated value of S and ħw are 2.71 and 758 cm^-1, respectively. From figure it is clear that there is a good matched with experimental and stimulated data.

Conclusion

The synthesized MgSiSO₃:Eu²⁺ inorganic phosphors successfully made using modified solid state reaction method. The excitation and emission spectra confirmed the luminescence was due to Eu²⁺ rare-earth metal ions. The excitation spectrum was broad and was due to ⁸S_7/2 state → 4f⁶5d¹ state and emission spectrum was also broad which was due to 4f⁶5d¹ state → ⁸S_7/2 transition. This confirms the doping occurred in the phosphor successfully. Further, the electron-vibration interaction study showed that the experimental