Multifunctional role of dysprosium in HfO2: stabilization of the high temperature cubic phase, and magnetic and photoluminescence properties.

Title Multifunctional role of dysprosium in HfO2: stabilization of the high temperature cubic phase, and magnetic and photoluminescence properties.
Authors S. Kumar; S.B. Rai; C. Rath
Journal Phys Chem Chem Phys
DOI 10.1039/c7cp02800h
Abstract

Hafnium oxide (HfO2) can exist in different crystalline structures such as monoclinic at room temperature, tetragonal at 1700 °C and cubic at 2600 °C. In the present study, nanocrystalline powders of HfO2 synthesized by a Pechini type sol-gel technique show a monoclinic phase, P21/c, at room temperature. By incorporating Dy into the HfO2 lattice, the intensity of all diffraction peaks corresponding to P21/c decreases and at a concentration of 11 at% of Dy, the monoclinic phase transforms completely to the cubic phase, Fm3[combining macron]m, showing a mixed phase of monoclinic and cubic at intermediate concentrations (5-9 at%) of Dy. For the first time, we have stabilized the high temperature cubic phase of HfO2 at room temperature by incorporating Dy. Selected area electron diffraction patterns confirm the monoclinic and the cubic phase as observed from the X-ray diffraction patterns. A mechanism for stabilization of the high temperature cubic phase in Hf1-xDyxO2 has been analyzed based on the substitution of dysprosium for hafnium ions and the formation of oxygen vacancies. While ferromagnetic ordering at room temperature observed in HfO2 nanoparticles is quenched after incorporating 1 at% of Dy, photoluminescence (PL) studies demonstrate excellent emissions in the blue and yellow region after exciting with UV light of wavelength 352 nm. Combining excitation and emission profiles, we have proposed a tentative energy band diagram illustrating the energetic processes taking place in Hf1-xDyxO2.

Citation S. Kumar; S.B. Rai; C. Rath.Multifunctional role of dysprosium in HfO2: stabilization of the high temperature cubic phase, and magnetic and photoluminescence properties.. Phys Chem Chem Phys. 2017;19(29):1895718967. doi:10.1039/c7cp02800h

Related Elements

Dysprosium

See more Dysprosium products. Dysprosium (atomic symbol: Dy, atomic number: 66) is a Block F, Group 3, Period 6 element with an atomic radius of 162.5. Dysprosium Bohr ModelThe number of electrons in each of dysprosium's shells is [2, 8, 18, 28, 8, 2] and its electron configuration is [Xe]4f10 6s2. The dysprosium atom has an atomic radius of 178 pm and a Van der Waals radius of 229 pm. Dysprosium was first discovered by Paul Emile Lecoq de Boisbaudran in 1886. In its elemental form, dysprosium has a silvery-white appearance. Elemental Dysprosium PictureIt is a member of the lanthanide or rare earth series of elements and, along with holmium, has the highest magnetic strength of all other elements on the periodic table, especially at low temperatures. Dysprosium is found in various minerals including bastnäsite, blomstrandine, euxenite, fergusonite, gadolinite, monazite, polycrase and xenotime. It is not found in nature as a free element. The element name originates from the Greek word dysprositos, meaning hard to get at.

Hafnium

See more Hafnium products. Hafnium (atomic symbol: Hf, atomic number: 72) is a Block D, Group 4, Period 6 element with an atomic weight of 178.49. Hafnium Bohr ModelThe number of electrons in each of Hafnium's shells is 2, 8, 18, 32, 10, 2 and its electron configuration is [Xe] 4f14 5d2 6s2. The hafnium atom has a radius of 159 pm and a Van der Waals radius of 212 pm. Hafnium was predicted by Dmitri Mendeleev in 1869 but it was not until 1922 that it was first isolated Dirk Coster and George de Hevesy. In its elemental form, hafnium has a lustrous silvery-gray appearance. Elemental HafniumHafnium does not exist as a free element in nature. It is found in zirconium compounds such as zircon. Hafnium is often a component of superalloys and circuits used in semiconductor device fabrication. Its name is derived from the Latin word Hafnia, meaning Copenhagen, where it was discovered.

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