Hydrothermal synthesis of prismatic NaHoF(4) microtubes and NaSmF(4) nanotubes.

A new example of tubular materials based on sodium rare-earth tetrafluorides, NaHoF(4) and NaSmF(4), has been fabricated by a simple hydrothermal method. In addition, an unusual nanotube with a perfect couple of an outer prismatic shell with an inner concentric prismatic nanorod at the center is found. According to the architectures of various products, the general growth mechanism of these tubes is proposed.