Credit: Badri Narayanan, Argonne National Laboratory
Saltwater helps a reversible phase transition occur in samarium nickelate (SNO). Under electrical bias, protons (H+) enter and diffuse into the SNO lattice (forming HSNO) with electron (e-) transfer from the counter electrode happening at the same time. This voltage-bias induced phase change results in exceptional changes in electrical resistivity and enables detection of sub-volt electric potentials in water. The samarium, nickel, hydrogen, and oxygen atoms are shown as purple, green, blue, and red spheres, respectively.