Dopant-driven phase transitions in correlated metal oxides
Reversible phase transitions of exceptional magnitude may be induced in correlated metal oxides by altering their chemical compositions through reversible introduction of dopant ions and electronic carriers into the correlated metal oxides. One or more catalyst electrodes may be deposited onto a surface of a film of a correlated metal oxide such as a perovskite or a transition metal oxide. Dopant ions and electronic carriers may be electrochemically introduced into the catalyst-deposited correlated metal oxide, for example by annealing the catalyst-deposited film of correlated metal oxide in a chamber containing the dopant molecules. In this way, a reversible phase transition of about five to eight orders of magnitude may be induced.
1. A system comprising:
a film of samarium perovskite nickelate, the film of samarium perovskite nickelate having at least one catalyst electrode deposited onto a surface thereof;
the film of samarium perovskite nickelate including a plurality of dopant ions and a plurality of electronic carriers introduced therein so as to chemically induce a non-volatile increase in resistivity of the samarium perovskite nickelate;
wherein the non-volatile increase in resistivity is between three and eight orders of magnitude.
2. The system of claim 1 , wherein the catalyst electrode comprises a hydrogen catalyst electrode.
3. The system of claim 2 , wherein the hydrogen catalyst comprises one of; Pt (platinum); and Pd (palladium).
4. The system of claim 1 , wherein the dopant ions and the electronic carriers have been dissociated from one or more dopant molecules, and
wherein the dopant molecules comprise hydrogen, and the dopant ions comprise protons.
5. The system of claim 1 , wherein the catalyst electrode is non-porous.
6. The system of claim 1 , wherein the catalyst electrode is porous.
7. The system of claim 4 , wherein the dopant ions and the electronic carriers have been dissociated from the dopant molecules, upon annealing of the film of samarium perovskite nickelate in a chamber containing the dopant molecules.
8. The system of claim 7 , wherein the dopant molecules comprise lithium, and the dopant ions comprise lithium ions.
9. The system of claim 7 , further comprising:
a layer grown on top of the film of samarium perovskite nickelate, wherein the layer is conductive for the dopant ions but insulating for the electronic carriers;
a gate electrode that is permeable to the dopant ions, the gate electrode configured to dissociate the dopant molecules so as to cause the dopant ions to diffuse into the film of samarium perovskite nickelate and into the layer;
wherein the at least one catalyst electrode comprises a source and a drain; and
wherein the system is a transistor.
10. The system of claim 9 , wherein the dopant molecules comprise hydrogen, the dopant ions comprise protons, and the layer comprises a proton conductive layer that is also an electron insulator; and
wherein the gate electrode is a proton-permeable gate electrode.
11. The system of claim 10 , wherein the proton conductive layer comprises yttrium-doped barium zirconate (BYZ).
12. The system of claim 10 , wherein the proton-permeable gate electrode comprises evaporated Pd.
13. The system of claim 1 , wherein the chemical induction of the non-volatile increase in resistivity of the samarium perovskite nickelate includes a reduction of the valence state of Ni (nickel) in the samarium perovskite nickelate, from Ni 3+ to Ni 2+ .
14. The system of claim 13 , wherein the reduction of the valence state of Ni in the samarium perovskite nickelate occurs through a reversible electrochemical process given by:
Sm 3+ +Ni 3+ 3O 2− H + +e − ↔Sm 3+ +Ni 2+ 2O 2− +OH − .