Table 2.

A comparison of several O-containing materials

Parent compound	M	Involved orbitals	Eorb (eV)60	dO-M (pm)59	rM (pm)b	λ (pm)	Tcmax (K)
La2CuO4a	La	O 2s – La 5p	−26.36	255	115	0	35
Sr2RuO457	Sr	O 2s – Sr 4p	−27.69	270	113	17	1.5
Sr2IrO4	Sr	O 2s – Sr 4p	−27.69	277	113	24	N/A

“M” represents the neighboring atom of O. E_orb is the energy level of the involved orbital in M. d_O-M is the bond length. r_O and r_M are ionic radii of O and M, respectively (r_O = 140 pm). λ = d − r_O – r_M is a characteristic parameter for the O–M bond.

^aChu et al.⁶²

^bPauling ionic radii.