1. A CPP magnetic read head, comprising:
a seed layer on a lower lead layer;
an antiferromagnetic layer on said seed layer;
a pinned layer on said antiferromagnetic layer;
a spacer layer on said pinned layer;
a free layer on said spacer layer;
a cap layer on said free layer;
said cap layer and said free layer together forming a first pedestal having a first maximum width;
said seed layer, said antiferromagnetic layer, said pinned layer, and said spacer layer together forming a second pedestal having a second maximum width that is greater than said first maximum width;
said first pedestal being precisely aligned relative to said second pedestal whereby said second pedestal overlaps said first pedestal by the same amount everywhere; and
said first pedestal having sidewalls that are steeper than those of said second pedestal.
2. The CPP read head described in claim 1 wherein said read head has a GMR ratio of at least 1% and a series resistance that is less than about 50 ohms.
3. The CPP read head described in claim 1 wherein said second maximum pedestal width is between about 1 and 12 times said first maximum pedestal width.
4. The CPP read head described in claim 1 wherein said first pedestal has an aspect ratio between about 1.5 and 30.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A process for converting a carbon containing fuel and water vapor into a reformate gas comprising hydrogen, carbon monoxide and carbon dioxide, using water molecules that diffuse through a membrane by steam permeation reforming, the process comprising:
(a) providing a ceramic membrane comprising an oxide ceramic having intrinsic and extrinsic oxygen ion vacancies, and having first and second surfaces; wherein the oxide ceramic capable of reacting with gaseous water molecules at the first surface by the reversible reaction, H2O(g)+VO\u2022\u2022+OxO2OH\u2022O; and the oxide ceramic capable of producing gaseous water molecules at the second surface by the reversible reaction, 2OH\u2022OH2O(g)+VO\u2022\u2022+OxO;
(b) contacting water vapor with the first surface;
(c) contacting the reformate gas with the second surface;
whereby solid state ambipolar diffusion of oxygen ion vacancies and protons across the membrane occurs; and the ambipolar diffusion produces a net diffusion flux of water molecules through the membrane from the first surface to the second surface; and,
whereby reaction of the water molecules with the carbon containing fuel generates the reformate gas;
whereby the chemical activity of water molecules at the first surface is maintained greater than or equal to the chemical activity of water molecules at the second surface.
2. The process of claim 1, wherein the carbon containing fuel comprises a solid carbon containing fuel.
3. The process of claim 2, wherein the solid carbon containing fuel is coal or pyrolized biomass.
4. The process of claim 1, wherein the carbon containing fuel comprises a solid, electrically conductive carbon fuel rod.
5. The process of claim 4, wherein the carbon fuel rod is an anode electrode in contact with the ceramic membrane.
6. The process of claim 1, wherein the ceramic membrane comprises a perovskite ceramic.
7. The process of claim 6, wherein the ceramic membrane has a nominal stoichiometry of BaCe0.9Y0.1O3-\u03b4, where \u03b4 is 0 to 0.05.
8. The process of claim 1, wherein the ceramic membrane is non-conducting with respect to electrons with an ionic transference number greater than 0.8.
9. The process of claim 1, wherein the ceramic membrane has a protonic conductivity of at least about 5 millisiemens per centimeter at a temperature of 700\xb0 C.
10. The process of claim 1, wherein the process occurs at a temperature of 650\xb0 C. to 850\xb0 C.
11. The process of claim 1, wherein the process occurs at a temperature of about 700\xb0 C. to about 750\xb0 C.
12. The process of claim 1, wherein the hydrocarbon fuel is selected from the group consisting of methane, methanol, propane, ethanol, liquid paraffin, kerosene, and diesel fuel.
13. The process of claim 1, wherein the hydrocarbon fuel is methane.
14. The process of claim 1, wherein the ceramic membrane has a thickness less than about 1 millimeter.
15. The process of claim 1, wherein the first surface is in contact with air.
16. The process of claim 1, wherein the ceramic membrane is a proton conducting ceramic electrolyte of a fuel cell.
17. The process of claim 16, wherein the fuel cell comprises a cathode in direct contact with at least a portion of the first surface of the ceramic membrane.
18. The process of claim 17, wherein the cathode is selected from the group consisting of metals, metallic alloys, metallic and oxide composites, and mixed conducting oxides.
19. The process of claim 17, wherein the cathode is selected from the group consisting of platinum, a nickel alloy, and a mixed protonicelectronic conducting ceramic cathode less than about 20 microns in thickness.
20. The process of claim 17, wherein the cathode is stable against oxidation and corrosion in moist, oxidizing atmospheres at temperatures less than about 850\xb0 C.
21. The process of claim 16, wherein the fuel cell comprises an anode in direct contact with at least a portion of the second surface of the ceramic membrane.
22. The process of claim 21, wherein the anode is selected from the group consisting of metals, metallic alloys, metallic and oxide composites, and mixed conducting oxides.
23. The process of claim 21, wherein the anode is selected from the group consisting of a metallic platinum, a nickelnickel alloy, and a mixture of nickel oxide and oxide ceramic.
24. A process for generating electricity, comprising:
contacting a reformate gas from a carbon containing fuel source with the anode of a fuel cell and contacting oxygen and water vapor with the cathode of a fuel cell, the fuel cell comprising:
an anode selected from the group consisting of a metallic anode, solid carbon-containing anode, and a mixed conducting anode;
a cathode selected from the group consisting of a metallic cathode and a mixed conducting cathode;
a proton-conducting ceramic electrolyte between the anode and the cathode, wherein the ceramic electrolyte comprises an oxide ceramic having intrinsic and extrinsic oxygen ion vacancies, and having first and second surfaces; wherein the oxide ceramic is capable of reacting with gaseous water molecules at the first surface by the reversible reaction, H2O(g)+VO\u2022\u2022+OxO2OH\u2022O; and the oxide ceramic is capable of producing gaseous water molecules at the second surface by the reversible reaction, 2OH\u2022OH2O(g)+VO\u2022\u2022+OxO; and
an external load connecting the anode and the cathode;
establishing a water vapor concentration gradient by having a first partial pressure of the water vapor at the cathode exceed a second partial pressure of water vapor at the anode, and passing water vapor through the electrolyte from the cathode side to the anode side by steam permeation;
converting chemical energy in the form of protons with high electrochemical potential into electrical energy by electrochemical oxidation.
25. The process of claim 24, wherein the carbon containing fuel comprises a solid carbon containing fuel.
26. The process of claim 25, wherein the solid carbon containing fuel is coal or pyrolized biomass.
27. The process of claim 24, wherein the carbon containing fuel is in contact with the anode.
28. The process of claim 24, wherein the anode comprises a solid, electrically conductive carbon fuel rod.
29. The process of claim 24, wherein the reformate gas comprises hydrogen, carbon monoxide and carbon dioxide.