Wet Chemistry
Who hasn't experimented with growing beautiful blue copper sulfate crystals from solution as a child? That material is actually a very interesting quantum spin chain system. In fact, many quantum magnetic materials are grown from solution, see T. Yankova, D. Hüvonen, S. Mühlbauer, D. Schmidiger, E. Wulf, S. Zhao, A. Zheludev, T. Hong, V. O. Garlea, R. Custelcean, G. Ehlers, Crystals for neutron scattering studies of quantum magnetism , Philosophical Magazine 92, 2629 (2012); arXiv:1110.6375. The process is in theory not complicated. In practice, though, there is a lot of trial and error involved in selecting the optimal growth parameters. One is rewarded with beautiful samples, some of which are displayed in our quantum materials Gallery. The picture above shows thermal-gradient growth of two other quantum spin chain materials, namely K2CuSO4Cl2 and K2CuSO4Br2, as described in detail in the PhD thesis of Dr. Manuel Hälg (2015).
Many of the quantum magnetic materials grown with wet-chemistry methods, like the dimer system (C5H6N2F)2CuCl4 grown with the slow-cooling technique [D. Blosser, PhD thesis (2019)], contain hydrogen. This is a huge problem for neutron scattering, because protons have a very large incoherent cross section. Neutrons are scattered out of the sample and contribute to huge noise levels. The only way around this is to use deuterium-enriched samples. Deuterated versions of some organic ligands can be procured commercially. For others, as in the case of (C5H6N2F)2CuCl4, we perform catalytic deuteration in specialized "pressure cookers" in our lab. Samples grown from deuterated starting chemicals are then mounted for neutron scattering experiments.