Although temperature and composition are common synthetic variables in solid state chemistry, pressure is not. This may be in part due to the expense of the apparatus needed and in part because we work in a target-rich environment with many viewpoints and a large periodic table. I purchased a Walker type synthetic system about 30 years ago that, in recent years especially, has been worth the trouble it takes to use it. The pressure is relatively low in such systems compared to what one gets in a diamond cell, but the sample volumes are much larger. The system was purchased from a small company called Rockland Research, run by Peter McNutt, who, if I understand correctly, was one of the former group members of David Walker himself. Our Depths of the Earth system, although nominally easier to use, is in fact not easier to prepare samples for, and might be the only thing in my lab that I ever discarded out of frustration.

Several postdoctoral fellows and graduate students have succeeded in finding new materials in our system or modifying it, but the major successes in recent years has been due to the patience and synthetic skill of my former postdoctoral fellow now lab manager Danrui Ni. Many new materials, including oxides chalcogenides and halides have been found in our system, and it is my intention to describe enough of our work in the latter two categories of materials to give interested audience members ideas about what works at applied pressures up to 6 GPa and what doesn’t.