## 2 Synthesis of Yttrium
### The Sol-Gel Method  
The Sol-gel method of yttrium preparation is a preferable technique used by several researchers. In this method, yttrium nitrate and yttrium chloride were used as precursors with methanol. To accelerate oxygen gaps, mAP-123 Poloxamer can be inserted [36]. The manufacturing set-up was heating at 700 and 900 \({}^{\circ}\)C with various molar ratios of (1:1 and 1:2). The characteristic absorption bond of Y-O vibration was shown to be the same as Y\({}_{2}\)O\({}_{3}\) matrix. XRD can analyze the structural phase. The crystalline obtained was determined by the Scherrer equation within the range (21 to 32) nm. Y\({}_{2}\)O\({}_{3}\) using the sol-gel method was reported by [PERSON] et al. [37]. In their experiment, a hybrid polymer glycol citrate polymer, glycerol citrate polymer (GCP), and Y\({}_{2}\)O\({}_{3}\) nanoparticles were synthesized. The antibacterial ability of citrate-based polymer nanoparticles is reportedly involved in biomedical applications, as citrate has been from a natural source. In 2003, [PERSON] et al. [35] synthesized Y\({}_{2}\)O\({}_{3}\) Eu-doped nanopowder using ethylene tetraacetic acid (EDTA) complex with a comparatively low temperature of 600-100 \({}^{\circ}\)C and using metal nitrate as precursors. EDTA and polyethylene glycol were acting as a chelating factor and polymerization activators, and from the mentioned solution system, Y\({}_{2}\)O\({}_{3}\) Eu nanopowder was extracted. EDTA was reported to be the best chelator to the cations and offered stable complex with good solubility. All materials with precursors were blended on a molecular basis in a solution, which helps regulate the composition and homogeneity. During the polymerization reac \begin{table}
\begin{tabular}{c c c c c} \hline \hline \# & **Precursors** & **Medium** & **Methods** & **Ref.** \\ \hline
1 & Yttrium, europium, chloride salts, HCL & Ammonia & Co-precipitation & [57] \\
2 & Yttrium nitrate, hafnium (IV) chloride, diammonium oxalate & Water & Co-precipitation & [56] \\
3 & Yttrium nitrate hexahydrate, Na\({}_{2}\)CO\({}_{3}\), KOH, and NaOH & Water & Co-precipitation & [58] \\
4 & Yttrium nitrate, nitric acid, ammonia & Water, alcohol & Precipitation & [41] \\
5 & Yttria powder, nitric acid, ammonia sulfate & Ammonia water & Precipitation & [59] \\
6 & yttrium nitrate and urea & Water & Precipitation & [60] \\
7 & Yttria, nitric acid, aluminum nitrate, urea & Water & Precipitation & [61] \\
8 & Y\({}_{2}\)O\({}_{3}\) (95 mol.\%) and Eu\({}_{2}\)O\({}_{3}\) (5 mol.\%) were dissolved in HNO\({}_{3}\), & Water & Precipitation & [62] \\
9 & Y\({}_{2}\)O\({}_{3}\) (95 mol.\%) and Eu\({}_{2}\)O\({}_{3}\) (5 mol.\%) were dissolved in AcOH & Ethylene glycol (EG), & Precipitation & [62] \\
10 & Y (NO\({}_{3}\))\({}_{3}\) (77 mL), Yb(NO\({}_{3}\))\({}_{3}\) (20 mL), Er(NO\({}_{3}\))\({}_{3}\) & EDTA & Precipitation & [63] \\
11 & (Y(NO)\({}_{3}\)-6H\({}_{2}\)O), Na\({}_{2}\)CO\({}_{3}\), KOH and NaOH & Ammonium hydroxide & Co-precipitation & [58] \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Synthesis of yttrium oxide by the precipitation method. tion, EDTA-stimulated PEG can provide an excellent suppressing cation assemblage, and homogenous gel Y\({}_{2}\)O\({}_{3}\): EU nanopowder with purity can be obtained. Particles seem to be spherical. It required no further milling or grinding. In addition, [PERSON] et al. [64] have postulated that Y\({}_{2}\)O\({}_{3}\) acts as a catalyst for the synthesis of pyrimidine in methanol media. Y\({}_{2}\)O\({}_{3}\) powders had been successfully synthesized through the sol-gel process using glycerol and polyethylene glycol as additives accompanied through low-temperature (550 \({}^{\circ}\)C) annealing, and the results show an intense bluish-white emission with a quantum yield as high as 64.6% under a wide range of UV-light excitation of (235-400) nm [65].