Transparent Er³⁺-Doped Y₂O₃ Ceramics with Long Optical Coherence Lifetime.

Current research on transparent ceramics focuses on achieving high optical transmission and low structural disorder in rare-earth-doped systems. Prior studies have demonstrated that nanoparticle size influences ceramic transparency and optical properties. However, the specific impact of nanoparticle size on Er³⁺ doping in Y₂O₃ remains unclear. Established knowledge shows that smaller particles can improve densification and optical clarity. Yet, the relationship between particle size and ion site homogeneity is not fully understood. This paper addresses that uncertainty by comparing two NP sizes. The study aims to clarify how particle size affects optical coherence and structural disorder. It also seeks to quantify the optical transmission and spectral line widths in the material. No prior work had resolved the interplay between NP size and Er³⁺ site occupancy. This gap motivated the experimental approach described in the abstract.

The goal of this work is to evaluate the effect of nanoparticle size on the optical and structural properties of Er³⁺-doped Y₂O₃ ceramics. The specific problem is to determine whether smaller or larger NPs yield better optical coherence and transparency. The motivation stems from the need to optimize materials for applications requiring high optical quality and low spectral broadening. The study compares 200 nm and 40 nm NPs in ceramic synthesis. It measures optical transmission and spectral line widths as key indicators. The researchers propose that smaller NPs may lead to fewer structural defects. This hypothesis is tested through hot isostatic pressing and optical analysis. The study also aims to quantify the inhomogeneous and homogeneous broadening of Er³⁺ transitions. The ultimate goal is to identify the optimal NP size for high-performance ceramics.

The study uses hot isostatic pressing to fabricate transparent ceramics from Er³⁺-doped Y₂O₃ nanoparticles. Two NP sizes—200 nm and 40 nm—are analyzed for their impact on ceramic properties. Optical transmission is measured across the 1000–2000 nm wavelength range. Spectral line widths are determined using high-resolution spectroscopy at 2.5 K and 0.65 T magnetic field. The inhomogeneous broadening of the ⁴I_15/2 to ⁴I_13/2 transition is quantified for the C₂ site. Homogeneous line width is calculated from the spectral data. The Er³⁺ concentration is fixed at 11.5 ppm for all samples. The structural disorder is inferred from the measured spectral widths and transmission data.

The 40 nm NPs produced ceramics with 80% optical transmission in the 1000–2000 nm range. This is higher than the transmission observed for 200 nm NPs. The inhomogeneous broadening of the ⁴I_15/2 to ⁴I_13/2 transition is 0.42 GHz for the C₂ site. The homogeneous line width is 11.2 kHz at 2.5 K and 0.65 T magnetic field. These values suggest minimal structural disorder in the Er³⁺ sites. The low broadening indicates high site homogeneity in the 40 nm NP-derived ceramics. The results show that smaller NPs lead to better optical coherence. The optical transmission and spectral line widths are consistent with low structural defects.

The authors conclude that 40 nm NPs yield higher optical transmission and lower spectral broadening than 200 nm NPs. This suggests that smaller particles improve the structural homogeneity of Er³⁺ sites. The low inhomogeneous and homogeneous line widths indicate minimal site disorder. The 80% transmission in the 1000–2000 nm range supports the use of 40 nm NPs for transparent ceramics. The results suggest that NP size is a critical factor in determining material quality. The study does not claim that 40 nm NPs are the only viable option. However, they propose that this size offers superior optical coherence. The findings are specific to Er³⁺-doped Y₂O₃ and do not generalize to other dopants or materials.