Table 1 Crystal-structural parameters of the catalysts from Rietveld refinement and the chemical titration method.

		BSCF (single perovskite)	NBSCF (double perovskite)	NBCFM (triple perovskite)
Space group		Pm3¯m	Pmmm	P4/mmm
Phase structure		Cubic	Orthorhombic	Tetragonal
Lattice parameter	a (Å)	3.979	3.856	3.871
	b (Å)	3.979	3.827	3.871
	c (Å)	3.979	7.737	11.676
Unit cell volume (Å³)		62.997	114.174	175.866
Oxygen deficiency, δ		0.234	0.379	0.495