GB2206571A - Barium cerate doped with gadolinium - Google Patents
Barium cerate doped with gadolinium Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
- G01N27/4073—Composition or fabrication of the solid electrolyte
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
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- C01F17/00—Compounds of rare earth metals
- C01F17/30—Compounds containing rare earth metals and at least one element other than a rare earth metal, oxygen or hydrogen, e.g. La4S3Br6
- C01F17/32—Compounds containing rare earth metals and at least one element other than a rare earth metal, oxygen or hydrogen, e.g. La4S3Br6 oxide or hydroxide being the only anion, e.g. NaCeO2 or MgxCayEuO
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M6/00—Primary cells; Manufacture thereof
- H01M6/14—Cells with non-aqueous electrolyte
- H01M6/18—Cells with non-aqueous electrolyte with solid electrolyte
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
- H01M8/124—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte
- H01M8/1246—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte the electrolyte consisting of oxides
- H01M8/126—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte the electrolyte consisting of oxides the electrolyte containing cerium oxide
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- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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- C01P2002/34—Three-dimensional structures perovskite-type (ABO3)
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- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
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Abstract
A doped barium cerate-based solid electrolyte for use in electrochemical devices wherein the dopant is gadolinium. The perovskite material is useful in electrochemical devices.
Description
PEROVSKITE COMPOUNDS
The present invention relates to rare earth doped barium cerates of the perovskite structure and the use thereof as ionic conductors in electrochemical devices in general and in fuel cells in particular.
Fuel cells are electrochemical devices in which the chemical energy of a conventional fuel is converted into low voltage, direct current electrical energy.
Fuel cells using liquid electrolytes normally operate at low temperatures and require relatively expensive fuels containing low levels of carbon monoxide, such as hydrogen, to generate electrical energy. Hence, attention has been turned to the use of solid, ceramic electrolytes which can be operated at higher temperatures thus exhibiting higher tolerance for carbon monoxide and enabling the use of relatively cheaper fuels such as fossil fuels. In order to be technically or commercially viable such solid electrolytes should essentially have: (a) good oxide ion conductivity and negligible electronic
conductivity at the operating conditions, (b) adequate mechanical strength, and (c) an easy fabrication process.
Several complex metal oxides when used as solid electrolytes possess one or more of the above desirable characteristics. Typical amongst these are the oxides having a fluorite structure, e.g.
ZrO2:Y or CeO2:Gd, or perovskite structure, e.g. CaTiO3:Mg or BaCeO3 :Y.
Takahashi et al in Energy Conversion, 11, pp 105-11 (1971), have measured the ionic conductivities of a number of doped perovskites. For example CaTiO3:Mg exhibited a specific ionic conductivity of approximately 4 x 10-3 ohm'lcm-l at 800*C. A fuel cell incorporating the above electrolyte and operating at 1000 C delivered a current density of 25 mA cm~2 at 0.7V.
Iwahara et al in Solid State Ionics, 3/4, pp 359-63, (1981) and in J. Power Sources, 7, pp 293-301 (1982) report the results of their studies on the use of strontium cerate, SrCeO3, doped with ytterbium, yttrium or magnesium as solid electrolytes in fuel cells. They concluded that such systems were protonic conductors on the basis of EMF measurements in oxygen and hydrogen concentration cells as well as in fuel cells. A fuel cell incorporating a
SrCeO3:Yb pellet approximately 0.5 mm thick achieved current densities of 20 mA cm~2 and 50 mA cm~2 at 800 and 10000C respectively at a terminal voltage of 0.7V.
Further investigations on solid electrolytes of the ceria based perovskites type are reported by Maiti et al in Solid State Ionics, 13, pp 285-292 (1984) and J. Power Sources, 14, pp 295-303 (1985).
These authors used systems containing barium cerate, BaCeO3, doped with each of yttrium, lanthanum, holmium and neodymium and found that these systems had high oxide ion conductivity; notably BaCeO3:Y had an oxide ion conductivity of 5 x 10-3 ohm~1 cm-l at 800~C. From a systematic study of the oxygen partial pressure dependence of the conductivity, these authors determined the ionic transport numbers for such systems to be about 0.5 in air at 800*C.
Thus, the reported specific ionic conductivities of perovskites indicate that these materials will only be suitable for use in solid state fuel cells operating at over 800 C. Consequently, the materials cost for constructing fuel cells based on the above electrolytes would render them commercially unattractive.
It is therefore the object of the present invention to develop solid electrolytes of the perovskite type which are capable of operation at temperatures significantly below 8000C without substantial loss of conductivity and performance of the fuel cell.
Accordingly, the present invention is a doped barium ceratebased solid electrolyte for use in electrochemical devices characterised in that the dopant is gadolinium.
According to another embodiment the present invention is a solid electrolyte for use in an electrochemical device, said electrolyte having the composition: BaCe l-XGdxo3-~ 2 where x represents the amount of the dopant gadolinium ions replacing the cerium ions in the BaCeO3 lattice.
According to a further embodiment the present invention comprises an electrochemical device which has a solid electrolyte of the perovskite structure having an oxide ion conductivity from 0.13 x 10-3 at 2000C to 38 x 10-3 at 8000C characterised in that the solid electrolyte is a gadolinium doped barium cerate of the formula: BaCe 1 xGdxO3#x 2 wherein x is the amount of the dopant gadolinium ions replacing the cerium ions in the BaCeO3 lattice.
The value of x quoted herein is in terms of atom fraction, based on the combined number of gadolinium and cerium atoms in the mixed oxide composition.
The solid gadolinium doped barium cerates will hereafter be referred to as 'BCG" for convenience.
The amount of dopant gadolinium ion 'x' in the solid electrolyte is suitably from 0.01 to 0.30 atom fraction, preferably from 0.10 to 0.20 atom fraction.
The solid electrolytes of the present invention can be used in electrochemical devices such as fuel cells, oxygen gas monitor and electrosynthetic cells. The solid electrolytes can be used in a variety of shapes. In the present context, the performance of the electrolyte was tested in the shape of pellets in a fuel cell but is not intended to be limited either to such shapes or for use in fuel cells. With this proviso, the solid electrolyte doped with gadolinium may be prepared for instance as follows in a sequence of steps which include oxide preparation, ball milling, pressing and sintering.
(a) Oxide Preparation
In view of the difficulties in handling barium oxide which readily absorbs carbon dioxide and water from the atmosphere, the mixed oxides were prepared by heating a mixture of a barium compound, which readily decomposes into the oxide in situ, with the other oxides, enabling a reaction between the oxides.
The appropriate amounts of the starting materials (BaCO3, CeO2 and Gd2O3) are suitably ground together and heated e.g. in air at elevated temperature e.g. 1100C.
The composite powders so formed are preferably re-ground and heated e.g. at about 14000C in air for a further extended period to achieve completion of reaction. It is preferable to check the mixed powder at this stage e.g. by X-ray powder diffraction analysis to ensure that the products show a pure BaCeO3-type phase.
(b) Ball-milling
The powder product from step (a) is suitably ground again in a ball mill for a short period and sieved using an appropriate sieve.
The particle size distribution of the desired powder is suitably in the range of 5-40 micrometers.
(c) Pressing
The sieved powders from step (b) can be made into a uniform paste using a liquid medium well known for this purpose in the art, e.g. ethylene glycol, glycerine and the like, and pelletised e.g. by pressing in a pellet die. It is suitably pressed for about 1 minute at a pressure of 4 tons/cm2 so as to achieve a compactness (or relative density) of at least 90% and an inter-connected porosity value not greater than 15. Pellets so formed are dried e.g. for 2 hours under an infra-red lamp.
(d) Sintering
The pellets from step (c) are sintered e.g. for about 10 hours at elevated temperature e.g. 1475 C. The sintering may be carried out in an oxidising or a reducing atmosphere, suitably in a reducing atmosphere, preferably using 5Z hydrogen in nitrogen. Subsequently the sintered product is cooled gradually.
In the case where the final sintering step is carried out in an oxidising atmosphere, e.g. air, the final product has a darkish appearance. However, the product sintered in a reducing atmosphere is virtually white in colour.
The ionic conductivity and the ionic transport number of the solid electrolytes of the present invention may be measured by impedance spectroscopy carried out over a range of oxygen partial pressures.
The technique for impedance spectroscopy for the measurement of the ionic conductivity offers the advantage of enabling the bulk conductivity to be resolved from resistive and capacitive effects arising at grain boundaries within the material and at the electrode/material interface.
By contrast, two terminal measurements, performed using d.c. or fixed frequency a.c. will give misleading results regarding the bulk properties, as a result of these resistive and capacitive effects.
In practice, impedance spectroscopy involves measurement of the real and imaginary parts of the impedance over a range of frequencies, e.g. using an a.c. bridge, and plotting the results, e.g. as imaginary versus real impedance.
Although existing ceria-based electrolytes (e.g.
ceria-gadolinia) possess the required ionic conductivity for fuel cell applications, it is known that in the reducing environment encountered at the anode of a fuel cell, such electrolytes acquire partial electronic conductivity with consequent loss of fuel cell voltage. (cf. P.N. Ross and T.G. Benjamin, J. Electrochem Soc, 122, 255-9 (1975)). However, we have found that BCG-based electrolytes are highly resistant to reduction by hydrogen at 800 C and are thus very stable thereby underlining their suitability for use in hydrogen-oxygen fuel cells. The BCG pellets of the present invention are particularly suited for fuel cells operating at 550-650"C.
The present invention is further illustrated with reference to the following Examples.
Examples 1. Preparation and Characterisation of BCG Pellets
In the preparation of samples the following sequence of operations was followed to ensure that pellets were of the correct composition and phase purity, and of sufficiently low gas permeability.
(a) Oxide Preparation
Starting materials (BaCO3, CeO2 and Gd203) used in varying amounts as shown in Table 1 below were ground together in an agate mortar for a minimum of 10 minutes and heated in an alumina crucible for 10 hours at 1100 C.
The resultant powders were re-ground and heated for a further 10 hours at 1400C. X-ray powder diffraction analysis of products showed a pure BaCeO3-type phase.
(b) Ball-milling
Powders from step (a) were ground in an agate ball mill (FRITSCH, Model Pulverisette 7) for 30 minutes and sieved using a 42 micrometers sieve. Particle size analysis showed a size distribution in the range 5-40 micrometers.
(c) PressinR
Powders from step (b) were made into a uniform paste using ethylene glycol and pressed in a pellet die for 1 minute at a pressure of 4 tons/cm2. Pellets were dried for 2 hours under an infra-red lamp.
(e) Sintering
Pellets from step (d) were packed in coarse powders of their own composition, sintered for 10 hours at 1475C in an atmosphere of 5% hydrogen in nitrogen. Subsequent cooling was restricted to a rate of 5C/minute in order to avoid excessive thermal stress in the pellets.
Table 1
Weight in grams of Startin# Materials used to Prepare the Family
of Compounds BaCe1-x2Nx23-x 2 BaC03 CeO2 Gd2 3 x
10.00 8.289 0.4592 0.05
10.00 7.854 0.9184 0.10
10.00 7.417 1.3776 0.15
10.00 6.980 1.8367 0.20
10.00 6.544 2.2959 0.25 10.0D 6.108 2.7552 0.30 2. Results 2.1 X-ray Powder Diffraction results
The products of the above preparation were subjected to X-ray powder diffraction analysis using a copper K-alpha radiation, which showed them to be predominantly of a perovskite structure. The d-spacings and relative peak heights are given in Table 2 for x = 0.10. The same d-spacings are found in samples of BCG for values of x in the range 0 to 0.30 (inclusive), in varying degrees of sharpness.
Table 2
Main lines in the X-ray diffraction pattern of BCG for x = 0.10. The above lines are found in samples of BCG for values of x in the range 0 to 0.30 in varying degrees of sharpness.
d-Spacin# (A) Peak Height
4.40
3.11 100
2.654 < 1
2.541
2.203 14
2.194 9
1.800 10
1.795 19
1.56 1
1.555 10
1.393 4
1.389 5 2.2 Conductivity Results
Metallic electrodes of silver or platinum pastes (Johnson
Matthey P-2100 and E-8210) were applied to the pellet faces and baked at temperatures of 4000C and 1000 C respectively. Impedance spectra were obtained over the frequency range 5 Hz to 13 MHz using an impedance analyser (HP 4192A). The conductivity of BCG was studied as a function of temperature in air and isothermally as a function of oxygen partial pressure (Po2). Partial pressures were fixed using column-dried nitrogen/oxygen and nitrogen/hydrogen gas mixtures of pre-determined ratios. An equilibration period of 1-2 hours was allowed between each set of measurements, after which stable conductivities were obtained. For hydrogen/nitrogen mixtures, the Po2 was determined using a zirconia oxygen monitor made from a ZrO2:Y tube with platinum electrodes and operated at 600 C using pure oxygen as a reference atmosphere.
Impedance spectra were obtained on samples of BCG for x = 0.05 to x = 0.30 over the temperature range 200 to 800eC.
The spectra for x = 0.1 at 200 and 600 C, given in Tables 3 and 4, illustrate the behaviour of BCG at low and high temperatures respectively.
when plotted in the complex plane, the impedance data in
Table 3 resolve a semi-circle passing through the origin, characteristic of the bulk resistivity, and an oblique line due to the electrodes.
Similarly, the data in Table 4 resolve part of a semi-circle, characteristic of the bulk resistivity, and the electrode impedance
Table 3
Experimental Impedance Spectrum. Corrected for Sample Shape.
obtained for a pellet of BCG (x=0.1) with Silver Paste
Electrodes at 2000C Frequency Impedance. Real Part Impedance, Imam. Part
(Hz) (ohm cm) (ohm cm)
100.0 54624 47209
158.5 43203 38787
251.2 34355 31757
398.1 27525 25486
631.0 22379 20101
1000.0 18556 15685
1584.9 15683 12198
2511.9 13455 9500
3981.1 11683 7411
6309.6 10268 5765
10000.0 9159 4453
15848.9 8307 3404
25118.9 7669 2564
39810.7 7218 1898
63095.7 6914 1388
100000.0 6724 1027
158489.3 6606 796
251188.6 6532 684
398107.1 6468 687
630957.3 6398 811
1000000.0 6279 1077
1584893.0 6035 1507
2511886.0 5549 2067
3981071.0 4708 2615
6309573.0 3543 2884 10000000.0 2323 2707
Table 4
Experimental Impedance Spectrum, Corrected for Sample Shape,
obtained for a pellet of BCG (x=0.l) with Silver Paste
Electrodes at 600'C
Frequency Impedance, Real Part Impedance, Imag. Part
(Hz) (ohm cm) (ohm cm)
5.0 142.8 13.2
6.3 141.1 12.6
10.0 137.9 11.6
15.8 134.8 10.9
25.1 131.8 10.3
39.8 129.0 9.8
63.1 126.2 9.5
100.0 123.5 9.2
158.5 120.9 9.1
251.2 118.3 8.9
398.1 115.8 8.7
631.0 113.3 8.7
1000.0 110.7 8.6
1584.9 108.2 8.5
2511.9 105.7 8.4
3981.1 103.2 8.2
6309.6 100.8 8.0
10000.0 98.5 7.7
15848.9 96.3 7.4
25118.9 94.3 7.2
39810.7 92.4 7.2
63095.7 90.5 7.4
100000.0 88.6 7.8
158489.3 86.4 8.4
251188.6 83.9 9.1
398107.1 81.0 9.9
630957.3 77.7 10.4 1000000.0 74.4 10.6 1584893.0 71.2 10.4
Table 4 - Continued
Experimental Impedance Spectrum, Corrected for Sample Shape,
obtained for a pellet of BCG (x=0.1) with Silver Paste
Electrodes at 6000C Frequency Impedance, Real Part Impedance, Imam.Part
(Hz) (ohm cm) (ohm cm)
2511886.0 68.7 10.2
3981071.0 67.0 - 10.8
6309573.0 66.1 14.0
10000000.0 63.2 25.2
The bulk conductivity of BCG is given in Table 5 as a function
of temperature and doping level x. It can be seen that at any one
temperature the highest conductivity lies between those for the
values of x = 0.1 and x = 0.2.
Table 5
Conductivity of BCG as a Function of Temperature and Doping Level x
x Conductivity (x 10-3 ohm-1 cm~l) 2000C 400 C 5000C 6000C 7000C 800"C 0.05 0.091 - 3.9 8.0 15.4 30.3 0.10 0.134 3.6 7.8 14.7 24.4 38.5 0.20 0.122 3.9 9.0 13.1 - 37.3 0.30 0.0022 1.7 5.1 5.2? 8.1 15.4 It can be seen from the data in Table 6 below that under
comparable conditions the BCG system of the present invention
exhibits a superior conductivity to that of the prior art (as
described by Virkar and Maiti).
Table 6
Conductivity in air, of yttrium-doped barium cerate BaCe0~gYO~102~g as determined by Virkar and Maiti in J. Power Sources 14, 295-303
(1985)* and in the present invention
Conductivity (x 10-3 ohm-1 cm~1) Temperature 7 ( C) (Virkar & Maiti)* Present Reported Found Invention 400 -~ 2.0 3.6 600 2.4 8.7 14.7 800 10 30 38.5 *Not according to the invention.
The conductivities extracted from the impedance data and
tabulated above are total electrical conductivies and as such
contain an ionic and an electronic contribution, the relative
magnitudes of which are described by the ionic transport number.
The ionic and electronic contributions to the conductivity have
been resolved by measurement of the dependance of the total
conductivity on the oxygen partial pressure (Po2). It is known that
the ionic conductivity is invariant with Po2, while the electronic
part has either a positive Pop dependance (p-type) or a negative Po: dependance (n-type). For example, from the data for BCG (x = 0.1)
at 600 C, given in Table 7, the ionic contribution was determined as
11 x 10-3 ohm-lcm-l while the electronic contribution, in pure
oxygen, was determined as p-type and of the value
5.6 x 10-3 ohm#1cm#1.
Table 7
Conductivity of BCG (x=0.1) as a Function of Oxygen Partial Pressure
(Po2) at a Temperature of 6000C
Po2 Conductivity (atm) (x 10-3 ohm-1 cm 1) 1 16.7 0.20 13.9 0.05 12.8 0.02 12.5 0.001 10.8 1.6 x 10-24 11.4 3.6 x 10-25 11.5 5.8 x 10-26 11.6 1.7 x 10-26 10.9 3.2 x 10-27 10.7 10-27 10.9 From similar conductivity Po2 data obtained at a range of temperatures, the ionic transport number was determined and is presented in Table 8.
Table 8
Experimental Transport Number ti for BCG (x=0.1) derived from
Measurement of the Po2-Dependence of the Conductivity
at 400 to 800'C
Temperature ti C 400 0.96 500 0.89 600 0.66 800 0.41 Surprisingly, the p-type conductivity observed at high Po2 does not affect the performance of BCG systems of the present invention when used as fuel cell electrolytes as will be shown below.
2.3 Construction and Operation of Fuel Cells
Hydrogen-oxygen fuel cells were constructed by applying metallic paste electrodes to both faces of a BCG pellet and sealing this to the end of a tube of re-crystallised alumina ceramic.
Platinum (Johnson-Matthey P-2100) was used for the anode (H2 electrode), while silver (Johnson-Matthe E-8210) was used for the cathode (02 electrode). Electrical connections were made to the electrodes by means of platinum leads. The assembly was mounted in a temperature controlled furnace and the temperature was monitored using a chromel-alumel thermocouple. The gases, dried oxygen and hydrogen were arranged to purge each compartment of the fuel cell.
The current was set using a d.c. current source (Keithley model 220) while voltage measurements were carried out using a high impedance electrometer (Keithley model 617).
The voltage-current density performance using a BCG system (x = 0.1, thickness 0.42 mm) in a fuel cell at 600-800iC is reported in Table 9 below.
Table 9
Performance at 600, 700 and 800-C of a hydrqgen-oxygen fuel cell
based on a pellet of BCG (x = 0.1) of thickness 0.42 mm, with
platinum anode and silver cathode
600-C 700'C 800-C I (mA cm2) V (=V) I (mA cm~2) V (mV) I (mA cm~2) V (mV) 0 1105 0 1087 0 1028 5 1037 25 938 25 958 10 964 50 752 50 885 15 887 55 700 75 807 20 803 75 503 100 764 25 712 100 210 125 634 30 614 115 19 150 537 35 508 175 430 40 396 200 314 45 282 225 188 50 165 250 50 It is a feature of the present invention that current densities of 25 mA cm~2 at 6000C and 105 mA cm~2 at 8000C are achieved at a terminal voltage of 0.7V. A cell of this type (where x = 0.1) when operated at 80 mA cm~2 was stable for a test period of 1000 hours at 800 C.
For comparison with prior art solid electrolytes a ceria-gadolina (CG) system, hitherto believed to have the best ionic conductivity in a fuel cell, was compared as electrolyte with the
BCG system of the present invention. The results of the CG system are tabulated in Table 10 below whereas those of the BCG system is shown in Table 11. It is clear from these results that the BCG system of the present invention is vastly superior to the prior art
CG system in spite of (a) using a relatively lower amount of gadolinium and (b) using a greater thickness of the electrolyte, which factors should normally adversely affect the results.
Table 10
Performance at 8000C of a hydrogen-oxyRen fuel cell based on a
pellet of CG* (20% Gd) of thickness 0.9 mm with platinum
anode and silver cathode
Current Density Voltage (mV) (ma cm-2) CG 0 692 4 647 8 598 12 517 16 416 20 350 24 336 *Ceria-gadolina system (Not according to the invention).
Table 11
Performance at 8000C of a Hydro#en-oxy#en fuel cell based on a pellet of BCG (x = 0.1) of thickness 1.5 mm with platinum anode
and silver cathode
Current Voltage Density (mV) (ma cm ) BCG 0 1089 5 1031 10 963 15 892 20 808 25 717 30 613 35 497 40 370 45 232 50 85
Claims (3)
- Claims: 1. A doped barium cerate-based solid electrolyte for use in electrochemical devices characterised in that the dopant is gadolinium.
- 2. An electrolyte as claimed in claim 1, having the composition: BaCe 1#xGdxO3#x/2 where x represents the amount of the dopant gadolinium ions replacing the cerium ions in the BaCeO3 lattice.
- 3. An electrochemical device which has a solid electrolyte of the perovskite structure having an oxide ion conductivity from 0.13 x 10-3 at 2000C to 38 x 10-3 at 8000C characterised in that the solid electrolyte is a gadolinium doped barium cerate of the formula: BaCel-xGdxOg-x/2 where x represents the amount of dopant gadolinium ions replacing the cerium ions in the BaCeO3 lattice.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08716147A GB2206571A (en) | 1987-07-09 | 1987-07-09 | Barium cerate doped with gadolinium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08716147A GB2206571A (en) | 1987-07-09 | 1987-07-09 | Barium cerate doped with gadolinium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8716147D0 GB8716147D0 (en) | 1987-08-12 |
| GB2206571A true GB2206571A (en) | 1989-01-11 |
Family
ID=10620355
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08716147A Withdrawn GB2206571A (en) | 1987-07-09 | 1987-07-09 | Barium cerate doped with gadolinium |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2206571A (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0523696A1 (en) * | 1991-07-17 | 1993-01-20 | Matsushita Electric Industrial Co., Ltd. | Mixed ionic conductors and the preparation thereof |
| EP0677741A2 (en) * | 1994-04-12 | 1995-10-18 | Matsushita Electric Industrial Co., Ltd. | Oxygen sensor |
| EP0726609A1 (en) * | 1995-02-09 | 1996-08-14 | Tokyo Yogyo Kabushiki Kaisha | Solid electrolyte for a fuel cell and its manufacturing method |
| EP0766085A2 (en) * | 1995-09-28 | 1997-04-02 | Matsushita Electric Industrial Co., Ltd. | Electrochemical device |
| EP0772042A3 (en) * | 1995-11-02 | 1998-07-08 | Matsushita Electric Industrial Co., Ltd. | Hydrocarbon sensor |
| WO2004113229A1 (en) * | 2003-06-25 | 2004-12-29 | Itn Nanovation Gmbh | Mixed metal oxides and use thereof in co2 sensors |
| WO2005117190A2 (en) * | 2004-05-25 | 2005-12-08 | Protonetics International, Inc. | Systems and methods to generate hydrogen and electrical power in a reversible compound fuel cell |
| US7045231B2 (en) | 2002-05-22 | 2006-05-16 | Protonetics International, Inc. | Direct hydrocarbon reforming in protonic ceramic fuel cells by electrolyte steam permeation |
| US7332237B2 (en) | 2003-01-27 | 2008-02-19 | Protonetics International, Inc. | Stream reforming of solid carbon in protonic ceramic fuel cells |
-
1987
- 1987-07-09 GB GB08716147A patent/GB2206571A/en not_active Withdrawn
Non-Patent Citations (2)
| Title |
|---|
| J. POWER SOURCES 14 PP 295-303 (1985) * |
| MAITI ET AL SOLID STATE IONICS 13, PP 285-292 (1984). * |
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0523696A1 (en) * | 1991-07-17 | 1993-01-20 | Matsushita Electric Industrial Co., Ltd. | Mixed ionic conductors and the preparation thereof |
| US5387330A (en) * | 1991-07-17 | 1995-02-07 | Matsushita Electric Industrial Co., Ltd. | Mixed ionic conductors |
| EP0677741A2 (en) * | 1994-04-12 | 1995-10-18 | Matsushita Electric Industrial Co., Ltd. | Oxygen sensor |
| EP0677741A3 (en) * | 1994-04-12 | 1996-05-01 | Matsushita Electric Ind Co Ltd | Oxygen sensor. |
| EP0726609A1 (en) * | 1995-02-09 | 1996-08-14 | Tokyo Yogyo Kabushiki Kaisha | Solid electrolyte for a fuel cell and its manufacturing method |
| EP0766085A3 (en) * | 1995-09-28 | 1998-06-10 | Matsushita Electric Industrial Co., Ltd. | Electrochemical device |
| EP0766085A2 (en) * | 1995-09-28 | 1997-04-02 | Matsushita Electric Industrial Co., Ltd. | Electrochemical device |
| EP0772042A3 (en) * | 1995-11-02 | 1998-07-08 | Matsushita Electric Industrial Co., Ltd. | Hydrocarbon sensor |
| US5935398A (en) * | 1995-11-02 | 1999-08-10 | Matsushita Electric Industrial Co., Ltd. | Hydrocarbon sensor |
| US7045231B2 (en) | 2002-05-22 | 2006-05-16 | Protonetics International, Inc. | Direct hydrocarbon reforming in protonic ceramic fuel cells by electrolyte steam permeation |
| US7332237B2 (en) | 2003-01-27 | 2008-02-19 | Protonetics International, Inc. | Stream reforming of solid carbon in protonic ceramic fuel cells |
| WO2004113229A1 (en) * | 2003-06-25 | 2004-12-29 | Itn Nanovation Gmbh | Mixed metal oxides and use thereof in co2 sensors |
| WO2005117190A2 (en) * | 2004-05-25 | 2005-12-08 | Protonetics International, Inc. | Systems and methods to generate hydrogen and electrical power in a reversible compound fuel cell |
| WO2005117190A3 (en) * | 2004-05-25 | 2007-01-18 | Protonetics International Inc | Systems and methods to generate hydrogen and electrical power in a reversible compound fuel cell |
| US7255949B2 (en) | 2004-05-25 | 2007-08-14 | Protonetics International, Inc. | Systems and methods to generate hydrogen and electrical power in a reversible compound fuel cell |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8716147D0 (en) | 1987-08-12 |
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