New Compounds In₃Ti₂AO₁₀, In₆Ti₆BO₂₂, and Their Solid Solutions (A: Al, Cr, Mn, Fe, or Ga; B: Mg, Mn, Co, Ni, Cu, or Zn): Synthesis and Crystal Structures

New compounds, In₃Ti₂AO₁₀ (A: Al, Cr, Mn, Fe, or Ga) and In₆Ti₆BO₂₂ (B: Mg, Mn, Co, Ni, Cu, or Zn) were synthesized at and above 1000°C in air through solid-state reactions among the constituent cation oxide powders. They are isostructural with the monoclinic and/or orthorhombic In₃Ti₂FeO₁₀ having a pyrochlore-related crystal structure with a commensurate or incommensurate modulated structure. The high-temperature phase is orthorhombic, and the low-temperature phase is monoclinic. The lattice constants of In₃Ti₂AO₁₀ are as follows: In₃Ti₂AlO₁₀ (1200°C): a(Å)=5.833(2), b(Å)=3.371(2), and c(Å)=12.060(6); In₃Ti₂AlO₁₀ (1100°C): a(Å)=5.8368(7), b(Å)=3.3721(4), c(Å)=6.3402(8), and β(°)=107.87(1); In₃Ti₂CrO₁₀ (1200°C): a(Å)=5.9246(8), b(Å)=3.3562(5), c(Å)=6.3546(9), and β(°)=108.10(1); In₃Ti₂GaO₁₀ (1200°C): a(Å)=5.861(2), b(Å)=3.385(1), and c(Å)=12.094(4); In₃Ti₂GaO₁₀ (1000°C): a(Å)=5.8742(9), b(Å)=3.3828(5), c(Å)=6.353(1), and β(°)=107.87(1). In₃Ti₂AlO₁₀ and In₃Ti₂GaO₁₀ are polymorphic. The lattice constants of In₆Ti₆BO₂₂ are as follows: In₆Ti₆MgO₂₂ (1200°C): a(Å)=5.9236(7), b(Å)=3.3862(4), c(Å)=6.3609(7), and β(°)=108.15(1); In₆Ti₆MnO₂₂ (1200°C): a(Å)=5.9361(9), b(Å)=3.4031(5), c(Å)=6.3435(10), and β(°)=108.26(1); In₆Ti₆CoO₂₂ (1200°C): a(Å)=5.9243(5), b(Å)=3.3841(3), c(Å)=6.3495(6), and β(°)=108.18(1); In₆Ti₆NiO₂₂ (1200°C): a(Å)=5.9191(6), b(Å)=3.3729(3), c(Å)=6.3568(6), and β(°)=108.13(1); In₆Ti₆CuO₂₂ (1000°C): a(Å)=5.916(2), b(Å)=3.379(1), and c(Å)=12.029(4); In₆Ti₆ZnO₂₂ (1200°C): a(Å)=5.9223(6), b(Å)=3.3830(3), c(Å)=6.3576(6), and β(°)=108.16(1). In₆Ti₆BO₂₂ (B: Mg, Mn, Co, Ni, or Zn) are monoclinic and In₆Ti₆CuO₂₂ is orthorhombic. Solid solutions were synthesized in between In₃Ti₂AO₁₀ (A: Al, Cr, Mn, Fe, or Ga) and In₆Ti₆BO₂₂ (B: Mg, Mn, Co, Ni, Cu or Zn), and their lattice constants were determined. Temperature in the parenthesis means synthesis temperature, and all the lattice constants were measured at room temperature. The relationship between the unit cells of In₃Ti₂AO₁₀, In₆Ti₆BO₂₂, their solid solutions, and the constituent cation elements of A and B are discussed in terms of their tendency for site preference.