The ProboStat sample holder (NorECs) measures conductivity, impedance spectra, and Seebeck coefficients in materials at high temperature. The result of these measurements is only meaningful in a defined, controlled atmosphere. Controlling pO₂ or pH₂O is not a detail; it is the independent variable.

FlowSeg provides the atmosphere control side of the ProboStat setup.

Controlling pO₂

The 2Mix device blends two gas lines with precise mass flow control. Common configurations for high-temperature electrochemistry:

• O₂ / N₂ or O₂ / Ar, oxidizing atmospheres, any pO₂ from ambient down to ~10⁻⁴ atm
• H₂ / N₂ or H₂ / Ar, reducing atmospheres; pO₂ is set by the H₂/H₂O equilibrium at operating temperature
• CO / CO₂, fixed pO₂ buffers at intermediate temperatures

The software calculates and displays partial pressures in real time. Profiles with ramps and steps can be pre-programmed to run automatically through a sequence of atmospheres while the ProboStat logs the electrical response.

Controlling pH₂O

The 2Wet device adds a precise, metered amount of water vapor to the gas stream. The evaporation temperature is PID-controlled; the fluid volume dosed is tracked by mass. This gives direct, repeatable control of pH₂O independent of carrier gas flow rate, unlike a bubbler, which depends on temperature stability and flow rate for its output.

Typical use: stepping pH₂O across several decades while measuring proton conductivity or water uptake in a ceramic sample inside the ProboStat.

Wet reducing or oxidizing atmospheres

2Mix and 2Wet are used together when both pO₂ and pH₂O must be controlled simultaneously, the standard condition for characterizing proton-conducting oxides and mixed ionic-electronic conductors. The 2Wet humidifies the output of the 2Mix before it enters the ProboStat inlet.

Programmable measurement sequences

The FlowSeg software supports unlimited program segments with independent ramps and steps for each device. A typical session: step through several pO₂ values at multiple pH₂O levels, holding each condition long enough for the impedance measurement to stabilize. The atmosphere sequence runs unattended while the researcher monitors electrical data from the ProboStat interface.

For further details see Gas specifications, Fluids and humidification, and Software. To request a quote use the Enquiry form.