Tungsten bronze (TB) crystal material molecular design

The molecular design of TB-type crystal materials has made many new advances in recent years. Mainly reflected in: the filling A position applied to the new elements; filling the elements of the B position diversification and doping modification.

Table 1 lists some of the new crystals developed by Foster et al. through molecular design. It can be found that, in the development of TB-type crystal materials, the position of A has traditionally used Ba, Sr, Pb, K and other elements to fill in. In recent years, there have been new trends in the use of rare earth elements such as La and Ce. There are not many domestic reports of TB-type crystals of rare earth elements. However, there have been more systematic studies abroad; the traditional position of B is only occupied by a cation. In recent years, by introducing low-valence cations at this position, more cations can be introduced at the A site to balance the electricity price, which increases the room for molecular design in the A-site and also helps to obtain structurally stable TB crystals.

The microdoping of TB-type crystal materials can improve its performance and improve the crystal growth quality. Table 2 shows the changes in properties of SBN and KNSBN after doping.

It is worth mentioning that the application of TB-type crystal materials has progressed rapidly. For the classic TB-type crystal materials such as SBN and PBN, the preparation and properties of their ceramic materials and thin-film materials have been actively studied. Compared with foreign countries, the use of W-type TB-type crystal materials in domestic B-sites is less studied. Phosphate TB structure films have attracted great attention due to their good prospects for superconducting applications, but the research in this area is weak.