title: Magnetic structure and properties of the Na2CoP2O7 pyrophosphate cathode for sodium-ion batteries: a supersuperexchange-driven non-collinear antiferromagnet.
abstract: The crystal and magnetic structure and properties of the Na(2)CoP(2)O(7) Na(+)-ion battery cathode material have been characterized by magnetic susceptibility, specific heat, and variable-temperature neutron powder diffraction measurements. Na(2)CoP(2)O(7) crystallizes in the orthorhombic space group Pna2(1) with a = 15.4061(3) Å, b = 10.28854(9) Å, and c = 7.70316(15) Å, having a layered structure with slabs of [CoP(2)O(7)](∞) separated by Na cations. The magnetic property measurements and neutron diffraction data analysis reveal that the material undergoes long-range ordering to a noncollinear antiferromagnetic G-type structure below T(N) ≈ 6.5 K. The magnetic structure is rationalized as a result of supersuperexchange between Co(2+) atoms linked by phosphate groups.
authors.affiliation: Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan. prabeer@chemsys.t.u-tokyo.ac.jp
authors.forename: Prabeer
authors.initials: P
authors.lastname: Barpanda
authors.forename: Maxim
authors.initials: M
authors.lastname: Avdeev
authors.forename: Chris D
authors.initials: CD
authors.lastname: Ling
authors.forename: Jiechen
authors.initials: J
authors.lastname: Lu
authors.forename: Atsuo
authors.initials: A
authors.lastname: Yamada