ChemInform Abstract: La_8+xTi_8+yS₂₄O₄ Compounds Where x + y ≤ 2: A Series of Phases with Mixed‐Valent Titanium.

Abstract

La 8+x Ti 8+y S 24 O 4 Compounds Where x + y ≤ 2: A Series of Phases with Mixed-Valent Titanium.-Three new titanium oxysulfides, (V), (VIIa), and (VIIb) are prepared by thermal reactions of La 2 S 3 , Ti, S, and either La 2 O 3 or TiO 2 as oxygen source. All three compounds are tetragonal (space group P4/mmm; Z = 1) and are quite similar in structure to Sr 5.8 La 4.4 Ti 7.8 S 24 O 4 . They contain common 2 ∞ [(Ti 4 S 2 O 4 )(TiS 6 ) 4/2 ] (12 + δ)− oxysulfide layers and disordered/variable composition titanium sulfide layers that alternately stack along the c-axis of the unit cell. Moreover, they possess an unusual combination of solid solution formation, vacancies, and site disorders that allow for changes in structure, composition, and titanium oxidation state. -(TRANCHITELLA, L.