The synthesis process employed solid-state reaction methods to produce phosphors with varying CaO contents, specifically at
x values of 0, 0.2, 0.4, 0.6, 0.8, and 1.0. As the CaO content (represented by the
x value) increases, the crystalline structure of Ca
2+x
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The synthesis process employed solid-state reaction methods to produce phosphors with varying CaO contents, specifically at
x values of 0, 0.2, 0.4, 0.6, 0.8, and 1.0. As the CaO content (represented by the
x value) increases, the crystalline structure of Ca
2+xGa
4O
8+x + 0.01 Bi
2O
3 + 0.07 ZnO compositions underwent notable transformations. X-ray diffraction was used to characterize these structural changes, and we found that CaGa
2O
4, CaO, Ga
2O
3, and Ca
3Ga
4O
9 were clearly identified. The diffraction intensities of CaGa
2O
4 and CaO phases increased and those of Ga
2O
3 and Ca
3Ga
4O
9 decreased with the
x value. Our findings revealed that the photoluminescence excitation (PLE) spectra consistently peak around 340 nm across all samples, while the photoluminescence emission (PL) spectra exhibited slight variations within the range of 474–477 nm. Most notably, the intensity of both PLE and PL spectra demonstrated a non-linear relationship with CaO content, initially increasing with higher CaO concentration, reaching maximum intensity at
x = 0.4, and subsequently decreasing as the
x value continued to rise. This research provides valuable insights into the relationship between composition, crystal structure, and luminescent behavior in Ca
2+xGa
4O
8+x phosphor systems, and the theoretical mechanisms underlying these observed trends were thoroughly discussed.
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