Dysprosium titanate (Dy2Ti2O7 or Dy2TiO5) 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.[2][3]
Dysprosium titanate was one of the first materials that was discovered to be a spin ice, along with holmium titanate (Ho2Ti2O7), in 1997.[4] 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.[5]
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.[6] The study demonstrated the existence of Dirac strings in dysprosium titanate and the presence of monopole characteristics at low temperatures.[7]
Structure
The Dy2Ti2O7 phase exhibits a cubic pyrochlore structure where the Dy3+ ions form a network of corner-sharing tetrahedra.[4][8] It is notable for its ability to withstand structural change in the presence of radiation from high energy ions.[2]
Dy2Ti2O7 can be "stuffed" by adding additional lanthanide atoms into the pyrochlore to generate Dy2TiO5.[9] 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.[3] This can, however, pose difficulties when characterizing this compound through the use of neutron diffraction.[10]
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.[11][12]
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,[13][14] all of which make dysprosium titanate a favorable material to use in control rods for nuclear reactors.[2][12]
Specifically, this material is used in the control rods for industrial thermal neutron reactors such as the VVER-1000 reactor type.[15]
References
↑ 1.01.1Dolgikh V.A., Lavat E.A. (1991). "Preparation of new oxide nitrides with the pyrochlore structure". Russ. J. Inorg. Chem.36: 1389–1392.
↑ 2.02.12.2Sherrod, Roman; O'Quinn, Eric C.; Gussev, Igor M.; Overstreet, Cale; Neuefeind, Joerg; Lang, Maik K. (2021-04-16). "Comparison of short-range order in irradiated dysprosium titanates" (in en). npj Materials Degradation5 (1): 19. doi:10.1038/s41529-021-00165-6. ISSN2397-2106. Bibcode: 2021npjMD...5...19S.