Room-temperature mixed spin state of Co3+ in Sr2Co0.02Ga0.98NbO6 double perovskite: combined NMR and EPR studies in a potential inorganic pigment

Maneesha Varghese (1) , Struan Simpson (1, 2) , Gaynor Lawrence (1, 2) , Mathieu Duttine (1) , Paula Sanz Camacho (1) , Manuel Gaudon (1) , Olivier Toulemonde (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
2 The Chemistry Department

The structural and optical properties of the refractory oxides Sr2CoxGa1–xNbO6 (x = 0 and 0.02) were investigated using powder X-ray diffraction; 93Nb, 71Ga, and 59Co magic-angle spinning nuclear magnetic resonance; electron spin resonance; and UV–vis–NIR absorption. A flux using SrCl2 versus a ball milling strategy to stabilize rock salt-ordered Sr2CoxGa1–xNbO6 (x = 0 and 0.02) at low temperature was underlined. Sr2Co0.02Ga0.98NbO6 showed a tetragonal I4/m crystalline structure with a slight lattice distortion index in the range of 0.04. Combined spectroscopic studies, further supported by UV–vis–NIR absorption analysis, definitively indicate an unusual mixed spin state of Co3+ at room temperature in the Sr2Co0.02Ga0.98NbO6 double perovskite that might be of interest for pale-brown inorganic pigments.

Domaines: Matériaux

Maneesha Varghese, Struan Simpson, Gaynor Lawrence, Mathieu Duttine, Paula Sanz Camacho, et al.. Room-temperature mixed spin state of Co3+ in Sr2Co0.02Ga0.98NbO6 double perovskite: combined NMR and EPR studies in a potential inorganic pigment. Journal of Physical Chemistry C, 2022, 126 (19), pp.8450-8460. ⟨10.1021/acs.jpcc.2c00191⟩. ⟨hal-03693036⟩