Potassium sulfate crystals with a copper content of 1.7% were synthesized, and the dependence of their refractive indices n_i(λ) and birefringence Δn_i(λ) on their dispersion was studied. It was found that the dispersion n_i(λ) in the spectral range of 300–700 nm is normal while introduction of the impurity leads to a decrease of ni and of the electron polarizability. The band energy structure of potassium sulfate crystal doped with 1.7% of Cu²⁺ was calculated. Introduction of the impurity leads to a decrease in the forbidden band width (E_g = 5.3 and 4.9 eV for pure and doped crystals respectively). The optical functions of doped potassium sulfate crystals were calculated.

中文翻译：

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铜掺杂K 2 SO 4晶体的折射率和能带结构

用1.7％的铜含量硫酸钾晶体合成，并且它们的折射率的依赖性Ñ_我（λ）和双折射的Δn_我（λ它们的分散体）进行了研究。发现在300–700 nm光谱范围内的色散n _i（λ）是正常的，而引入杂质会导致ni和电子极化率降低。计算了1.7％的Cu ²⁺掺杂硫酸钾晶体的能带结构。引入杂质会导致禁带宽度（E _g对于纯晶体和掺杂晶体，分别为5.3和4.9 eV）。计算了掺杂硫酸钾晶体的光学功能。