We have prepared the oxyhydride perovskite EuTiO(3-x)H(x) (x ≤ 0.3) by a low temperature CaH2 reduction of pyrochlore Eu2Ti2O7 and perovskite EuTiO3. The reduced EuTiO(3-x)H(x) crystallizes in the ideal cubic perovskite (Pm3̅m), where O/H anions are randomly distributed. As a result of electron doping by the aliovalent anion exchange, the resistivity of EuTiO(3-x)H(x) shows metallic temperature dependence. Moreover, an antiferromagnetic-to-ferromagnetic transition is observed even when a small amount of hydride (x ∼ 0.07) is introduced. The Curie temperature TC of 12 K is higher than those of any other EuTiO3-derived ferromagnets. The ferromagnetism can be explained by the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between the Eu(2+) spins mediated by the itinerant Ti 3d electrons. The present study shows that controlling the oxide/hydride ratio is a versatile method to tune magnetic and transport properties.

Substitution. -EuTiO 3-xHx (x  0.3) is prepared by low temperature CaH2 reduction of Eu 2Ti2O7 and EuTiO3 (475-650 C, 2 d) and characterized by XRD and magnetic measurements. The samples crystallize with the ideal perovskite structure in the cubic space group Pm3m, where O/H anions are randomly distributed. EuTiO3-xHx shows metallic resistivity and an antiferromagnetic-to-ferromagnetic transition at the Curie temperature of 12 K. The Curie temperature of EuTiO 3-xHx is higher than that of any other EuTiO3-derived ferromagnet. -(YAMAMOTO, T.; YOSHII, R.; BOUILLY, G.; KOBAYASHI, Y.; FUJITA, K.; KUSUSE, Y.; MATSUSHITA, Y.; TANAKA, K.; KAGEYAMA*, H.; Inorg. Chem. 54 (2015) 4, 1501-1507, http://dx.doi.org/10.1021/ic502486e ; Dep. Energy Hydrocarbon Chem., Grad. Sch. Eng., Kyoto Univ., Nishikyo, Kyoto 615, Japan; Eng.) -W. Pewestorf 17-010