Peculiarities of the Ni2+ ions in the crystal lattice of Bi12SiO20:Ni

► The Urbach's energy of the undoped BSO is not a constant. ► The strength of electron-phonon interaction decreases for Bi12SiO20:Ni in comparison with undoped BSO. ► The energetic diagram of the complex [NiO4]6− contains six electron transitions. ► In the case of BSO:Ni, Jahn-Teller effect is significant in comparison with the appearance of the spin-orbit interaction. ► In the region of frequencies 1000-2000 cm−1, Ni dopant increases the oscillator strength.