Structure of the RbTi0.98Zr0.02OPO4 single crystal at temperatures of 293 and 105 K

This paper reports on the results of precision X-ray structural investigations of a RbTi0.98Zr0.02OPO4 single crystal at temperatures of 293 and 105 K. It is established that the observed decrease in the temperature of the ferroelectric phase transition in RbTiOPO4 crystals doped with zirconium is associated with the increase in the Rb-O bond lengths. The structural factors responsible for the decrease in the electrical conductivity in these crystals are revealed. An analysis is made of the structure of the helical channels which in crystals of this family are considered to be a decisive factor for the manifestation of superionic conduction. It is shown that, in structures of the KTiOPO4 (KTP) type, the migration of ions in channels is most hindered inside the cavities.