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Sc (0, 1, 2, 3 mol%): Tm: LiNbO₃ crystals were prepared by the Czochralski method. The inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis test shows that, as the concentration of Sc${}^{3+}$ increases, the effective segregation coefficient of Sc${}^{3+}$ and Tm${}^{3+}$ decreases. The X-ray diffraction (XRD) analysis test shows that the lattice size increases first and then decreases. The optical homogeneity analysis test shows that the birefringence gradient of the Sc-3 sample is $4.7\times 10^{-}5$$\mathrm{\Delta }$R/cm${}^{-1}$, which is 1/3 of pure LiNbO₃. Research demonstrates that when the Sc${}^{3+}$ content reaches or exceeds the threshold value, ${\mathrm{\text{Nb}}}_{\mathrm{\text{Li}}}^{4+}$ is replaced completely, thus introducing non-intrinsic defects ${\mathrm{\text{Sc}}}_{\mathrm{\text{Li}}}^{2+}$ and ${\mathrm{\text{Sc}}}_{\mathrm{\text{Nb}}}^{2-}$. These defects are able to form ${\mathrm{\text{Sc}}}_{\mathrm{\text{Li}}}^{2+}-{\mathrm{\text{Sc}}}_{\mathrm{\text{Nb}}}^{2-}$ charge self-compensating defect groups, it will greatly increase optical homogeneity.

The reasons behind the fracture of the 220kV pipe busbar horizontal line clamp were analyzed. The fracture morphology, composition of chemical elements, metallographic examination and SEM of the fractured clamp were investigated by ICP-AES, SEM and metallurgical microscope. The test results show that many casting defects are found and that this batch of horizontal line clamp is substandard product. The horizontal line clamp structure design is unreasonable, which leads to the stress concentration in the location of the fracture. The corresponding suggestions are proposed.