I was wondering about using Van der Pauw method to test my electrolytes rather than by using EIS, but I'm not sure about it.
Can someone answer me and motivate the answer, please?
Thanks for your kindness
Dear Luca,
You can measure ionic conductors via vdP method. I was also curious about it in the past and have measured YSZ via IS on pellets and then by vdP (dc) and obtained the same results. Nice and simple basic experiment. So in principle it is possible. Please also note, that vdP can be used in ac measurements, but I have never tried, idea seems interesting.
As mentioned by Dr. Braun, you have to be a bit careful, especially if you are measuring new materials, because you will always measure total conductivities. In the case of YSZ I was sure it was oxygen, but for other materials it might not be true.
As a technical note, I would also be careful with voltages/currents you apply, as you should not go too high and in vdP it can be easy to go too high.
Best regards,
Sebastian
Thank you Dr Braun and Dr Molin! I will try firstly to compare the 2 methods on known pellets in order to acquire experience on vdP technique and then I will proceed with new pellets.
Again, your answers were really precious
Regards
Luca
as Artur Braun and Sebastian Molin. However, Eis is superior[1], especially useful in the case of non ideally blocking electrodes, that is more common in practice. Eis is able to discriminate between charge carriers (one type[2] of ion and electron) time constants (TC) of ionic conductors, during the measurements (capture the data type on the fly using TC) or better, later, through (Eis) modeling (& simulation). Also, Eis enhanced with B (magnetic field) is able to supplementare discrimination of charge carriers' concentrations and sign, either with the classic slab topology or with the RHall value in vdP.
1. Note1 : Eis in AC current i-mode for vdP.
2. Note2 : Two types of ions is easy to measure but two types of electronic carriers is more difficult in mixed ionic conductors.
Dear Luca,
you can apply the method but you have to consider that your sample should have a well define geometrical shape. In addition you can't separate the bulk and grain boundary contribution. You have a total conductivity related to the electrical conductivity. So if your sample has an electrical conductivity not neglible (as ceria doped electrolytes) this information can help you to undestand the electrochemical behavior.
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