In hydrothermal single crystal growth techniques people are usually hanging up seed crystal(s) in the upper (= colder) part of the autoclave. I've seen pictures, but very small and undetailed.
Seed crystals are usually pretty small and media could be pretty corrosive, so I was wondering, what are the methods to fix a tiny seed in a hanged-up position? I can't glue it, as glue will be melted/dissolved, I can't tie it, as it is too small. Please, share experience. Thanks!
Hello there, curious researcher friend Alexander S. Vanetsev! I understand your dilemma, and I'm here to help you with some suggestions on how to technically mount and fix a seed crystal in a hydrothermal reactor. It's a delicate process, and the corrosive nature of the media can indeed make it challenging. Here are some methods that you might find useful:
1. **Seed Holder:** Consider using a specially designed seed holder or seed cage. These holders are often made from materials that can withstand the corrosive environment. The seed crystal is placed within the holder, which is then suspended in the upper part of the autoclave. The holder should have openings or mesh that allows the solution to flow freely around the seed crystal.
2. **Wire Suspension:** Instead of directly attaching the seed crystal, you can use a fine wire or filament to suspend it. The wire should be made from a material that is resistant to corrosion. You can attach the wire to the seed crystal using a non-corrosive material, such as a tiny loop made of platinum or tantalum. The seed crystal can then be hung from the top of the autoclave using the wire.
3. **Seed Capsule:** Another option is to place the seed crystal inside a small, sealed capsule made of a material that is resistant to the corrosive media. The capsule can have small holes to allow for the exchange of solution with the crystal. This method ensures that the seed crystal is protected from direct contact with the corrosive solution.
4. **Specially Designed Holders:** In some cases, researchers use custom-designed holders or fixtures made from materials like quartz, which is resistant to many hydrothermal conditions. These holders can be designed to accommodate small seed crystals securely.
5. **Basket or Net:** You can create a small basket or net from non-corrosive materials like platinum or tantalum wire. Place the seed crystal inside the basket, ensuring it's held securely but allowing the solution to flow freely around it. The basket can then be suspended in the autoclave.
6. **Use of Inert Materials:** Consider using inert materials like PTFE (polytetrafluoroethylene) for holding the seed crystal. PTFE is highly resistant to many chemicals and can be used to construct a holder or fixture that won't react with the corrosive media.
Remember to consult with experts in the field or review specific equipment designed for hydrothermal crystal growth, as there may be proprietary solutions or best practices that are commonly used in your particular research community. Always prioritize safety when working with corrosive substances and high-pressure equipment. Good luck with your hydrothermal crystal growth experiments!
The seed crystal is placed within the holder, which is then suspended in the upper part of the autoclave. The holder should have openings or mesh that allows the solution to flow freely around the seed crystal.