fig4

Figure 4. Color of Si₃N₄ ceramics. (A) Digital photo of Si₃N₄ ceramics with varying Eu₂O₃ mass rations: The orange color deepens with increasing Eu₂O₃ content. (B) L*, a* and b* parameters of Eu-doped Si₃N₄ ceramics: As the Eu₂O₃ content increases, the value of L* decreases, while the values of a* and b* increase. (C) Emission spectra of all samples by monitoring 465 nm excitation: As the Eu₂O₃ content increases, the emission spectra tend to redshift but the intensity of light emission is weakened. (D) Reflectance spectra of Eu-doped samples (the inset shows the reflected light of the samples is located in the wavelength range from 556 to 602 nm). (E) Plot of (αhν)²vs. hν of Eu-doped Si₃N₄ ceramics (the insert shows the enlarged image of sample SEu-9). (F) Eg values for Si₃N₄ ceramics with different content of Eu₂O₃: An augmentation in the Eu₂O₃ content results in a reduction of Eg values, transitioning from 2.24 to 2.04.