Dear all,
I am trying to fabricate material via a solvothermal method.
I use Teflon lined stainless steel autoclave.
Most of the time in the papers, authors mentioned the volume of the autoclave that they used.
My question is that I should change the volume of autoclave based on the volume of the solvent.
Should I fill the autoclave up to a specific volume of its capacity?
My own experience in hydrothermal synthesis of zeolites has shown that for propre crystallization, the volume of the synthesis mixture should be at least 2/3 of the Teflon volume.
Use of low amount of synthesis mixture in large Teflon can cause complete solvent evaporation and poor crystallization.
On other hand, to create autogenous pressure, the Teflon should not be completely filled with the synthesis mixture.
You have to keep in mind that if the solution volume is significantly smaller the headspace in your autoclave, then all solvent can be evaporated at high temperature. In other words, the solution volume should not change much under your conditions of synthesis. At the same time, the solution volume should not be too large to give room for the thermal expansion of the solution volume.
My own experience in hydrothermal synthesis of zeolites has shown that for propre crystallization, the volume of the synthesis mixture should be at least 2/3 of the Teflon volume.
Use of low amount of synthesis mixture in large Teflon can cause complete solvent evaporation and poor crystallization.
On other hand, to create autogenous pressure, the Teflon should not be completely filled with the synthesis mixture.
According to my own experience, for better hydro- or solvothermal synthesis the volume should be 65-70%, more than 70% volume creates problems like it is become difficult to open the autoclave, and the teflon tube get stuck..... further less than 30% also evaporates as mentioned by Mohammad Darzinezhad Rami and Yurii V Geletii .
The more and less volume also sometimes effects the morphology and crystal size etc.......
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