Preparation and electrical properties of inorganic electride [Y 2 Ti 2 O 6 ] 2+ (2e - ).

Oxygen-depleted samples [Y 2 Ti 2 O 7- x ] 2 x + (2 x e - ) (0 ≤ x ≤ 1.0) were prepared by reducing Y 2 TiO 7 powders at 500 °C to 650 °C using CaH 2 as a reductive agent, where x represents the content of , which was determined by thermogravimetric analysis. Powder X-ray diffraction patterns illustrate that the pure pyrochlore phase is kept for the samples with x ≤ 1.0, whereas the apparent x values surpass 1.0, and the impurity phase Y 2 O 3 appears. The electride [Y 2 Ti 2 O 7- x ] 2 x + (2 x e - ) ( x ≈ 1.0) can be obtained under a reductive condition, in which the concentration of V O is 7.75 × 10 21 cm -3 . The electron paramagnetic resonance measurements gave the concentration of unpaired electrons in the electride as 1.30 × 10 21 cm -3 , indicating that the degree of the ionization of is less than 10%. Conductivity measurements for a sintered pellet sample (relative density ∼ 70%) indicate that the electride has quite high conductivity (∼1.09 S cm -1 at 300 K). The conduction was interpreted by using the variable range hopping mechanisms.