Description
The sample under test rests on a ca. 50 cm long support tube of alumina, inside a closed outer tube of alumina or silica. The sample can be contacted with 2, 3 or 4 electrodes of e.g. platinum, using disk, van der Pauw, or bar geometries. A spring-loaded alumina assembly holds the sample and electrodes in place. 16 electrical feedthroughs allow use of 4 shielded electrode leads, surface guard, and up to three thermocouples (e.g. for Seebeck coefficient measurements). Electrical connections are made via coax cables suitable for standard impedance spectrometer connectors, and standard thermocouple compensation cables. Gases can be fed in single or dual chamber modes directly onto or from electrodes, allowing measurements under controlled atmospheres, transport number measurements in gradients, and testing of fuel cell, pump, and sensor components. Gas supply is via Swagelok quick-connects.
Materials properties measured and applicable methods:
- Conductivity vs T, pO2, pH2O, etc.
- DC, AC, impedance spectroscopy
- Dielectric properties, loss, etc.
- Disk, van der Pauw, and bar geometries
- 2, 3, and 4 electrodes
- Ionic transport number
- Proton transport number
- H/D isotope effects
- Seebeck coefficient
- I-V-characteristics
- Fuel cell components and single cell testing
- Electrode kinetics
- Electrochemical pumping, gas permeation and electrocatalysis with gas analysis (e.g. GC or MS) on outlets
- Sensor testing
- Poling of ferroelectrics possible with the high-voltage (kV) version
- High-current version
- Annealing or sintering under controlled atmosphere
Specifications:
- Outer tube diameter: 40 mm
- Overall length: 75 cm, shorter versions available (-10, -20, -30 cm)
- Single end cell assembly
- Sample fixation: spring force via alumina rods
- All hot-zone electrode leads detachable via feedthrough mini-connectors
- Support tube systems from 10 to 24 mm diameter detachable
- For up to 24 mm diameter disk samples
- For up to 50 mm long bar samples
- Temperature: typical long term: < 1400ºC, short term: < 1600ºC
- Atmosphere: Oxidizing, reducing, or corrosive; wet or dry; from small overpressure to low vacuum
- 6 BNC electrode connections for impedance spectrometers etc.
- Internal shields bridging, ground and guard switches
- 3 thermocouple connections
- 4 Swagelok gas quick-connects to 1/8” tubing (other connections on request)
- Standard materials: Alumina AL23, Pt, Pt10%Rh, Stainless Steel
- Water cooling (or heating) of cold end base unit is possible
- Spare parts supply, also of hot zone consumables
Schematics to Show the Principle of Spring Loads
Regular 2-Electrode 4-Wire Setup with Dual Gas Supplies and Thermocouple
Example of Connection to Disk Samples for Impedance Measurements
Example of Connection to Disk Samples for Impedance Measurements
Part of Base Unit with Feedthroughs
ProboStatTM Design Options
Normal System
If you need to do electrical characterization at high temperatures and in controlled atmospheres, we suggest the ProboStat Normal System package. It includes what you need to get started with one method (e.g. 2 and 3-electrode measurements on disks. More methods can be added by adding components later on – the ProboStat base unit is ready for them all. The ProboStat can do RT-1600°C and can be used with any tube furnace of 30-50 cm length and 40-50 mm working diameter.
| This system contains the fully equipped base unit, one support tube assembly, one spring-load system, and electrodes for disk-type samples.
System contents:
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Typical Uses:
The package enables:
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This package represents an economic entry into dedicated studies with a more restricted set of methods and sample geometries. The package can at any time be expanded by more supports, electrode connections, etc., supplied by us or made by the user (we may supply instructions and parts as necessary.
We also offer a Normal Plus System that contains and does the same as the Normal system, but has more of the vulnerable parts and consumables like spring load alumina tubes and electrode connects.
Normal Plus System
System contains and does the same as the Normal System, but has more of the vulnerable parts and consumables like spring load alumina tubes and electrode connects.
| This system contains the fully equipped base unit, one support tube assembly, one spring-load system, and electrodes for disk-type samples.
System contents:
|
Typical Uses:
The package enables:
|
This package represents an economic entry into dedicated studies with a more restricted set of methods and sample geometries. The package can at any time be expanded by more supports, electrode connections, etc., supplied by us or made by the user (we may supply instructions and parts as necessary.
High Voltage System
High voltage feedthroughs allow experiments with ferro- and piezoelectric materials. We can deliver ProboStats with feedthroughs that tolerate >10 kV DC. The final tolerance in the sample compartment depends on the sample, pressure, atmosphere, and temperature. The high voltage feedthroughs can be fitted to new ProboStat base units; normally two of the normal outer chamber feedthroughs (“HC” and “LC”) are replaced by high voltage feedthroughs, and the BNC connectors are replaced by a high voltage version.
The final limiting breakdown voltage in the sample compartment may of course be further limited by the electrode and sample geometries, temperature, pressure and atmosphere, and the sample itself. We have tested the setup at various total pressures and temperatures using a 20 mm diameter, 3 mm thick alumina disk sample, and confirmed that the breakdown voltage follows mainly Paschen’s formula. At atmospheric pressure the breakdown voltage is then limited to 5-9 kV DC by the distance between the electrodes. At elevated temperatures or lower pressures, the breakdown voltage decreases and plasma discharge arises. At further lowering of the pressure into the low-vacuum the breakdown voltage again rises (as predicted by Paschen’s formula), and it is again possible to reach voltages exceeding 10 kV DC, also at elevated temperatures. This may be done by pumping on the normal base unit gas connections. For faster pumping it may be desirable to pump through a vacuum flange that can be attached to an open end enclosing tube.
Normally, it is the two outer chamber feedthroughs (“HC” and “LC”) that are replaced by high voltage versions. The two corresponding BNC connectors are also replaced by high voltage connectors. Some changes from the normal ProboStat are done in the wiring of shields, but otherwise the remaining feedthroughs are left as they are in the normal ProboStat, so that one may use up to three thermocouples or use the cell much as a normal ProboStat for normal low-voltage measurements. We may add one or two more high-voltage feedthroughs to the outer chamber, or one to the inner chamber, at special order.
The feedthroughs are made with brass conductors in the cold end of the base unit, insulated with fully dense (AL23) 99.7% alumina tubes through the base unit, and with two layers of insulating high-voltage-tolerant plastic in the hexagon connection box. In the sample chamber, the brass wires are terminated in male mini-contacts, standing on a 2 cm length of the alumina insulating tube. Contact to the high temperature zone is done with detachable wires made of, for instance, Pt or Au, soldered onto female mini-contacts, and insulated in an alumina capillary. The mini-contact zone is covered with a slide-on wider alumina tube. As said above, this construction withstands >10 kV DC in air at atmospheric pressure at room temperature.
Samples and electrode contacts may be held in place by using our standard alumina-based spring-loads.
The high- voltage feedthroughs can be fitted to new orders of ProboStat base units. (Retrofit is possible, but we do not recommend it.)
The high-voltage version allows polarization (poling) experiments with ferroelectric materials. It is compatible with connections and operations of for instance aixACCT Systems Gmbh.
The optical port that can be included in a vacuum flange at an open-ended enclosing tube gives possibility to access the sample with a laser interferometer. Other types of experiments enabled by the high-voltage feedthroughs comprise plasma electrodics (e.g. MS-studies of ion extraction from ionic conductors).
When using a thermocouple in a cell carrying high voltages, the thermocouple should be covered by the envelope alumina tube that we supply. This will prevent high-voltage discharge to the thermocouple.
Naturally, the user is responsible for all further precautions required to protect users and connected instrumentation toward possible high-voltage discharges.
In the high-voltage system two contacts are replaced with high insulated contacts.
System contents:
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Typical Uses:
The high-voltage system can also for regular characterization of dielectrics and electroceramics:
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Extensively Furnished System
The package comes with manuals, tools, simple mounting bench stand, etc. in a sturdy aluminium transport and storage case. The pictures show parts of a system as packed in the transport and storage case; layer with base unit, stand, tools, cables (top), layer with mainly outer and support tubes (middle) and layer with electrode connections, thermocouples, spring loads and gas tubes (bottom).
Such a package would be suitable for laboratories which value the cost-effectiveness of direct acquirement of new techniques without trial and error and development time.
The example may also be a suitable system for a PhD or post-doc project where a large range of techniques are expected to be applied in the studies of a material or class of materials.
Include it in your project proposal and budget!
Possible further upgrades comprise, for instance, an extra base unit to double the throughput of measurements by using the accessories more effectively, YSZ replacing alumina in supports for certain types of SOFC work, and spare parts.
System contents:
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Typical Uses:
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The figure below indicates schematically the types of electrode connections and thermocouples that can be supplied by us. They are all included in the extensively furnished system package.
Contents of the Extensively Furnished System
Additional Options
Furnace +
Test Stand
fuelcellmaterials offers an integrated, turn-key solid oxide fuel cell system for the researcher working with button cell testing. Included are the ProboStat along with a customized furnace and test stand. This complete system will allow you to focus on our SOFC research and not on creating the equipment needed for your research.
- Automatic hardware shutdown and purge gas for safe, reliable operation
- Testing software for user-friendly computer-controlled cell operation and experimentation
- Up to five mass flow channels with constant or stoichiometric-controlled reactant flow rates
- Anode and cathode stainless steel ambient temperature humidifiers
More information about the furnace and test stand options can be found at the SOFC Button Cell Test System.
Furnace
fuelcellmaterials, with the help of renowned furnace companies and test stand vendors, is able to offer specialized furnaces for use with the ProboStat. The furnace has a clam-shell design for easy access to the ProboStat and test samples.
