## 1 Introduction  
UV light can be generated as a consequence of electronic transitions of light sources through an Hg discharge. In low-pressure Hg discharge, the main emission line is located at a wavelength of 254 nm. This light is invisible and harmful to human bodies, so it has to be converted into visible light, which can be done with a combination of luminescent materials. These luminescent materials can strongly absorb light of that wavelength and efficiently convert it into visible light. Recently, white light emitting diodes (LEDs) have become popular because they have several advantages, including high efficiency, long lifetime, and low power consumption. Red phosphors are also helpful for generating white light when they are excited by blue or near-UV lights. To obtain phosphors with highly efficient emissions, it is important to choose the right compound materials and ensure they have outstanding physical and chemical stability. Numerous studies have explored different luminescent materials to enable the development of suitable phosphors. When lanthanide contraction ions are introduced into host materials, unfilled 4\(t^{\mathrm{N}}\) electron orbitals result, and these have attracted considerable attention. The resulting phosphors emit very luminescent emissions with specific light wavelengths because of variations in the energy level of some free electrons [1; 2; 3; 4]. These phosphors have been the most promising candidates for applications in fluorescent lamps and flat panel display devices, such as electroluminescence panels, plasma display panels, and field emission displays. A large number of isotropic compounds with perovskite structures, such as double perovskite oxides, have the general formula \(A_{2}BB^{\prime}\)O\({}_{6}\), in which \(B\)O\({}_{6}\) and \(B^{\prime}\)O\({}_{6}\) octahedra are corner-shared, alternately. The great flexibility of \(A\) and \(B\)(\(B^{\prime}\)) sites in \(A_{2}BB^{\prime}\)O\({}_{6}\) allows very rich substitutions, and this framework forms cube-octahedral cavities filled by A-site cations [5; 6]. Double perovskites with the formula \(A_{2}BB^{\prime}\)O\({}_{6}\), where \(A\) uses an alkaline earth, \(B\) and \(B^{\prime}\) are metal transition magnetic and nonmagnetic ions, and O is oxygen, have been investigated as magnetic materials for many years. For example, Sr\({}_{2}\)CrMoO\({}_{6}\) has been studied as a half-metallic system [7]. [PERSON] et al. recently reported room-temperature low-field magnetic resistance in the ordered double perovskite Sr\({}_{2}\)FeMoO\({}_{6}\)[8]. Complete ordering of Fe and Mo on the \(B\) and \(B^{\prime}\) sites of this metallic \(A_{2}BB^{\prime}\)O\({}_{6}\) double perovskite is predicted to give half-metallic ferromagnetism with localized majority-spin electrons on the Fe atoms [9; 10]. Recently, the study of \(A_{2}BB^{\prime}\)O\({}_{6}\)-based materials has increased due to various technological applications, such as inorganic oxide luminescent materials. The emitting materials are usually composed of activators and a host lattice. Some host lattice materials can produce light themselves, and some can produce light when doped with rare-earth activators (ions). Rare-earth ions are known to exist in various valence states, although the trivalent state is the most prevalent. Rare-earth ions can be applied in lighting devices and display panels due to their abundant energy levels across a wide spectrum range, from ultraviolet to near infrared. Sm- and Eu-based ions are the most commonly used dopants because they are stable in trivalent (Sm\({}^{3+}\) and Eu\({}^{3+}\)), as well as divalent (Eu\({}^{2+}\)), states. The luminescence of rare-earth ions doped in perovskite-type ceramics was actively investigated in the 1960s and 1970s because of interest in their ferroelectricity, phase transitions, and semiconducting properties [11].