Dysprosium titanate
Dysprosium titanate is an inorganic compound, specifically a ceramic of the titanate family. Two common phases of this compound exist with differing properties: Dy2Ti2O7 and Dy2TiO5. Dysprosium titanate is commonly used throughout the nuclear industry in nuclear control rods and as a host for nuclear waste.
History
Dysprosium titanate was one of the first materials that was discovered to be a spin ice, along with holmium titanate, in 1997. The existence of these materials was predicted by Linus Pauling in 1935, but neutron scattering experiments confirmed their existence as holmium titanate satisfied the model.Since its discovery as a spin ice, dysprosium titanate has continued to be a focus of research because the magnetic frustration that results from its pyrochlore lattice. In 2009, quasiparticles resembling magnetic monopoles were observed at low temperature and high magnetic field through neutron-scattering experiments. The study demonstrated the existence of Dirac strings in dysprosium titanate and the presence of monopole characteristics at low temperatures.
Structure
The Dy2Ti2O7 phase exhibits a cubic pyrochlore structure where the Dy3+ ions form a network of corner-sharing tetrahedra. It is notable for its ability to withstand structural change in the presence of radiation from high energy ions.Dy2Ti2O7 can be "stuffed" by adding additional lanthanide atoms into the pyrochlore to generate Dy2TiO5. In this instance, Dy3+ is 5-coordinated with oxygen, which produces an orthorhombic structure in the Dy2TiO5 phase. This phase also possesses a large neutron absorption cross section, which makes it desirable for various nuclear applications. This can, however, pose difficulties when characterizing this compound through the use of neutron diffraction.
Synthesis
Dysprosium titanate can be synthesized using various methods. The traditional synthesis process involve high-frequency induction melting of dysprosium oxide and titania in a cooled crucible. Sol-gel synthesis has also been utilized as a method to produce the compound in powder form. More recent developments have displayed the viability of mechanochemical processes using anatase and dysprosium oxide as reagents to produce dysprosium titanate nanopowders.Uses and Applications
Dysprosium titanate has become a desirable material in nuclear industry because of various properties. The compound has a large neutron absorption cross-section, low thermal expansion, high heat capacity, high radiation resistance, and a high melting point, all of which make dysprosium titanate a favorable material to use in control rods for nuclear reactors.Specifically, this material is used in the control rods for industrial thermal neutron reactors such as the VVER-1000 reactor type.