K₃Nb₃Ti₂O₁₁F₄

The asymmetric unit of K₃Nb₃Ti₂O₁₁F₄ contains two STX₆ octahedra where X = O, F or OF (= 1/4 F + 3/4 O) and ST = (3/5 Nb + 2/5 Ti). The K-atom environment is similar to that in ferroelectric phases, but the weak distortion of the octahedra and the occupation of their centres by Nb⁵⁺ and Ti⁴⁺ cations result in paraelectric behaviour.

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