Preparation and electrical properties of inorganic electride [Y₂Ti₂O₆]²⁺(2e^-)

Oxygen-depleted samples [Y₂Ti₂O_7- ]²(2xe^-) (0 ≤ x ≤ 1.0) were prepared by reducing Y₂TiO₇ powders at 500 °C to 650 °C using CaH₂ 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 Y₂O₃ appears. The electride [Y₂Ti₂O_7- ]²(2xe^-) (x ≈ 1.0) can be obtained under a reductive condition, in which the concentration of V_O is 7.75 × 10²¹ cm^-3. The electron paramagnetic resonance measurements gave the concentration of unpaired electrons in the electride as 1.30 × 10²¹ 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.