Dysprosium Compounds Research Articles

Magnetic properties of equiatomic rare earth cadmium compounds

The magnetization processes obtained in monocrystalline samples are presented for the ferromagnetic compounds of the equiatomic rare earth cadmium series. They are discussed in terms of crystalline electric field and bilinear and quadrupolar pair interactions. A close similarity appears with the isomorphous series with zinc. The importance of quadrupolar interactions is emphasized. They are, for instance, strong enough in DyCd to enforce the fourfold axis as easy magnetization direction instead of the threefold one which would be driven by the only crystalline electric field. A discussion of the magnetic properties of dysprosium compounds having the CsCl-type structure is then given.

Studies on rare earth carboxylates. III. X-ray and IR studies on Ln(C6H4OHCOO)3�H2O (Ln = La-Ho or Y)

The rare earth salicylate monohydrates Ln(C6H4OHCOO)3·H2O (Ln=La-Ho or Y) were prepared and subjected to X-ray powder diffractometric and infrared absorption spectroscopic investigations. The salts from lanthanum to gadolinium are found to be isomorphous and are indexed on a monoclinic unit cell with space groupP21/c-C 2h 5 (No. 14). Certain dissimilarities between the powder patterns of isomorphous terbium and dysprosium compounds and those of the lighter rare earths necessitated independent indexing of these two compounds, which are found to be monoclinic with space groupP21/c-C 2h 5 . Holmium and yttrium salts are isomorphous and are monoclinic with space groupP2/m-C 2h 1 (No. 10). The assignments of some of the observed bands to certain characteristic vibrations of various functional groups in the spectra of these salts have been done.

Absorption and luminescence spectra of dysprosium compound in non-aqueous solutions. Spectral intensity analysis.

Absorption and luminescence spectra of dysprosium compound were measured in non-aqueous solutions (alcohols, amides) within the region 5500 – 35000 cm −1. The oscillator strengths of the f-f absorption bands were determined. The intensities of the Dy +3 ground state absorption were analyzed based on the Judd-Ofelt theory. A polarizability effect on the intensity of f-f transition was considered. The quenching mechanism of luminescence of the 4F 9 2 level for Dy +3 ion in non-aqueous solutions was discussed.

Magnetic and electrical properties of heusler alloys with rare earths: RInAg 2

Rare earth ternary compounds RInAg 2 were prepared for all rare earths except europium and ytterbium. They crystallized with a Heusler-type structure (L2 1). The magnetic properties and the electrical resistivity were studied in the temperature range 1.6–300 K. The paramagnetic susceptibilities showed Curie-Weiss behaviour for all the compounds except SmInAg 2 which is a Van Vleck paramagnet. The asymptotic Curie temperatures θ p were negative throughout the series. The cerium, neodymium, samarium, gadolinium, terbium and dysprosium compounds ordered antiferromagnetically at low temperatures, but no order was observed above 2 K in PrInAg 2, HoInAg 2, ErInAg 2 or TmInAg 2. Inelastic neutron scattering experiments were used to determine the crystal electric field parameters in the cerium, praseodymium and neodymium compounds.

Absorption spectra of dysprosium compounds in nonaqueous solutions. Spectral intensity analysis

Absorption spectra of dysprosium compounds were measured in amides and D 2O within the 5500–35000 cm −1 region and in alcohols within the 7000–34300 cm −1 region. The oscillator strengths of f-f absorptions bands below 35000 cm −1 were determined. The intensities of the Dy 3+ ground state absorption were analyzed according to the Judd-Ofelt theory of forced electric dipole transitions. A good fit to the measurements was obtained with the intensity parameter given in Tables 4–6. The polarizability effect on the intensity of the f-f transition with high value matrix elements U (4) and U (6) were considered.

Mossbauer spectroscopy and magnetic properties of DyMgand ErMg

A 161Dy Mossbauer study has been performed on the cubic equiatomic compound DyMg. From the value of the hyperfine parameters, the isomer shift in the intermetallic compounds of dysprosium and the magnetic properties of the heavy rare-earth-magnesium system are discussed.

Mössbauer study of the Ising antiferromagnet DyPO4: Hyperfine parameters,g-factor anisotropy, and spin-lattice relaxation

M\"ossbauer spectroscopy of the 26-keV $\ensuremath{\gamma}$-ray transition in $^{161}\mathrm{Dy}$ was employed to study nuclear hyperfine interactions in Ising-like DyP${\mathrm{O}}_{4}$. Single-crystal and polycrystalline samples were studied over the temperature range $1.8\ensuremath{\le}T\ensuremath{\lesssim}300$ K, which included the N\'eel temperature ${T}_{N}=3.39$ K. For $0\ensuremath{\le}T\ensuremath{\lesssim}10$ K the spectra could be analyzed in terms of a "static" $S=\frac{1}{2}$ spin Hamiltonian $\mathcal{H}={A}_{z}{I}_{z}{S}_{z}+(\frac{{A}_{\ensuremath{\perp}}}{2})({I}^{+}{S}^{\ensuremath{-}}+{I}^{\ensuremath{-}}{S}^{+})+P[3{I}_{z}^{2}\ensuremath{-}I(I+1)]$. The measured components of the magnetic hyperfine tensor parallel and perpendicular to the tetragonal $c$ axis are, respectively, $\frac{{A}_{z}}{2}=\ensuremath{-}831\ifmmode\pm\else\textpm\fi{}4$ MHz and ${A}_{\ensuremath{\perp}}=\ensuremath{-}14\ifmmode\pm\else\textpm\fi{}5$ MHz. This is the first reported measurement of an ${A}_{\ensuremath{\perp}}$ term in M\"ossbauer studies of dysprosium compounds. Using the known ionic $g$-factor component, ${g}_{z}=19.32\ifmmode\pm\else\textpm\fi{}0.01$, we calculate $k=\frac{{A}_{z}}{2h{g}_{z}}=43.0\ifmmode\pm\else\textpm\fi{}0.2$ and hence ${g}_{\ensuremath{\perp}}=0.3\ifmmode\pm\else\textpm\fi{}0.1$. The ratio of quadrupole parameters for the excited and ground nuclear states of $^{161}\mathrm{Dy}$ is $\frac{{P}_{e}}{{P}_{g}}=0.986\ifmmode\pm\else\textpm\fi{}0.003$ with $\frac{{P}_{g}}{h}=60.3\ifmmode\pm\else\textpm\fi{}0.6$ MHz. For $T\ensuremath{\gtrsim}10$ K the spectra are relaxation broadened and can be described well using the time-dependent Hamiltonian $\mathcal{H}(t)=f(t){A}_{z}{I}_{z}{S}_{z}+P[3{I}_{z}^{2}\ensuremath{-}I(I+1)]$, where $f(t)=\ifmmode\pm\else\textpm\fi{}1$. These spectra were analyzed using a random-fluctuation stochastic model for $f(t)$ and incorporating the exchange splittings obtained from previous optical work on the ground Kramers doublet. The analysis then depends on a single relaxation parameter $\ensuremath{\Omega}(T)$. Between $T=16\mathrm{and}36$ K the relaxation is dominated by an Orbach spin-lattice process of the form $\ensuremath{\Omega}={\ensuremath{\Omega}}_{0}{e}^{\frac{\ensuremath{-}{\ensuremath{\Delta}}_{G}}{T}}$, where ${\ensuremath{\Delta}}_{G}\ensuremath{\simeq}70$ ${\mathrm{cm}}^{\ensuremath{-}1}$.

149Sm 3+ isomer shifts

Mössbauer effect isomer shifts are given for samarium and ten of its compounds. They are very well correlated with the isomer shifts of the corresponding compounds of dysprosium and gadolinium. The ratio of the changes in mean square nuclear radii are deduced.

Theoretical study of the electronic structure of some cubic intermetallic compounds of dysprosium using the augmented plane wave method

The energy bands and the nature of the conduction electrons have been studied for three intermetallic compounds of dysprosium, e.g., DyZn, DyCu and DyRh, following the augmented plane wave method. Density of states results are given and have implications for the stability of the structure. The charge densities and the number of conduction electrons inside and outside the APW spheres are calculated; it is shown that the character of conduction electrons within the Dy APW sphere is principally of d type for all the compounds. The consequence of the predominance of d electron in the conduction bands on the various physical parameters is discussed.

Studies on the electronic structure of some cubic intermetallic compounds of dysprosium following the self-consistent augmented-plane-wave method

The energy bands and the nature of the conduction electrons have been studied for two intermetallic compounds of dysprosium, i.e, DyZn and DyRh, following the self-consistent augmented-plane-wave (APW) method. The convergence of energy was found to be rapid for DyZn because the shell of $3{d}^{10}$ electrons for Zn lies below the conduction band. The Fermi energies (${E}_{F}$) have been calculated to be 0.421 and 0.477 Ry for DyZn and DyRh, respectively. The densities and the numbers of conduction electrons inside and outside the APW spheres in each of these compounds are calculated, and it is shown that the character of conduction electrons inside the APW sphere of Dy is predominantly of $d$ type. In order to see the accuracy of these results, self-consistent calculations were done for DyZn for different choices of the exchange potentials, and the calculated number of conduction electrons did not change significantly. The consequence of the predominance of $d$ electrons in the conduction band on the various physical parameters is discussed.

Investigation of ceramics on a base of zirconium and dysprosium compounds

Investigation of ceramics on a base of zirconium and dysprosium compounds

Mössbauer study of dysprosium equiatomic compounds with copper, silver, zinc and rhodium

Intermetallic cubic dysprosium compounds are studied by Mössbauer effect. The results are interpreted in terms of the ratio between crystalline field and exchange interactions. The influence of conduction electrons in discussed.

161Dy isomer shifts in dysprosium compounds

Mössbauer absorption spectra were obtained for the 25.7 keV transitions of 161Dy in dysprosium metal and several compounds at room temperature. Isomer shifts relative to DyF 3 are: Dy (metal), 3.05 mm sec −1; DyN, 0.85 mm sec −1; Dy 2O 3, 0.56 mm sec −1; DyH 2.9, 0.55 mm sec −1; DyH 2.1, 0.50 mm sec −1; DyF 3. 1 2 H 2O , −0.04; and Dy 2(SO 4 3.8H 2O, −0.46 mm sec −1. The relative isomer shifts of these compounds are attributed to varying degrees of covalency. The isomer shifts for the hydrides are compared to the predictions of the protonic and hydridic models for these compounds and appear to favor the hydridic model.

161Dy isomer shifts in dysprosium compounds

Objective Magnetic resonance imaging (MRI) has the potential to provide accurate quantification of structural changes in joint disease, with sensitivity to change, as it can provide direct visualization of the cartilage and bone. In this study, we investigated whether knee cartilage volume, as assessed by MRI, is sensitive to change over time in patients with osteoarthritis (OA).Design Sixteen patient volunteers (10 male, six female) with established OA of the knee were entered into the study and demographic data recorded. At baseline, 12 months and 37±2 months, patients underwent simple measures of disease severity, as well as extended weight-bearing AP knee X-rays. In addition the patient's index knee was imaged using MR at 1.0T using a 3-D spoiled gradient–echo sequence with fat-suppression, repetition time 50 ms, echo time 11 ms, flip-angle 40°, sagittal slice thickness 1.56 mm and in-plane pixel resolution 0.55 mm. Manual image segmentation was performed on all knee cartilage compartments and the respective cartilage volumes determined.Results Eleven of the original patients recruited completed the 3-year study. Radiographic features indicated that the majority had a spectrum of well-established OA at entry. The average decrease in medial tibiofemoral joint space width was 0.21±0.37mm (mean±S.D.). Comparison of MR images at baseline and 37±2 months indicated little evidence of cartilage lesion shape or size change in any of the compartments. There was no significant MRI volume change in any of the knee cartilage compartments over the course of 1 year. The change in total knee cartilage volume, as measured by MRI, was a loss of only 1.6%, or 0.36±1.3 ml (mean±S.D.), over the 3 years.Conclusions The failure to identify loss of cartilage volume over 3 years in this cohort of patients with established knee OA using MRI challenges the face validity of this endpoint to assess structural changes in OA. Copyright 2002 OsteoArthritis Research Society International. Published by Elsevier Science Ltd. All rights reserved.

Free ion hyperfine fields in intermetallic compounds of dysprosium

Recoilless absorption spectra of the 26-keV γ-rays of 161Dy m show that for all intermetallic compounds of Dy, except those containing Co or Fe, the value of H eff acting on the Dy nuclei does not differ by more than 2% from the free-ion value.

Crystallographic and Magnetochemical Studies on ABO3 Group Compounds of Lanthanon and Manganese Oxides

Perovskite-structured compounds have been prepared containing manganese oxide with praseodymium, neodymium, and dysprosium oxides. X-ray crystallographic data have been obtained for these compounds, and unit cell edge values of 3.82, 3.80, and 3.70 A are found for PrMnO3, NdMnO3, and DyMnO3, respectively. Magnetic susceptibilities of these compounds have been measured down to liquid-air temperatures and gram susceptibilities found to range from 40–158% above those indicated by additive values for the component oxides, highest increments being found in praseodymium systems. Susceptibility curves follow the Curie-Weiss law without deviation, and Weiss constants of 115, 112, and 62 have been found for the praseodymium, neodymium, and dysprosium compounds, respectively.

CharacteristicLAbsorption of X-rays for Elements of Atomic Numbers 62 to 77

Characteristic L x-ray aborption wave-lengths for nine elements of atomic numbers 62 to 77.---Since the $L$ absorption wave-lengths had been determined for elements of atomic numbers 55 to 60, 74, and 78 to 92, it was of interest to fill in the gaps. Accordingly compounds of samarium (62), gadolinium (64), dysprosium (66), erbium (68), ytterbium (70), tantalum (73), tungsten (74), osmium (76) and iridium (77) were precipitated upon filter paper and placed in the path of x-rays from the tungsten target of a Coolidge tube. In each case the three $L$ absorption bands together with the emission lines of $W$ were photographed, using a calcite crystal which was rotated with a constant angular velocity. The wave-lengths and the frequency numbers divided by the Rydberg constant, $\frac{\ensuremath{\nu}}{N}$, are tabluated. The energy levels within the atoms corresponding to the different absorption limits computed in terms of $\frac{\ensuremath{\nu}}{N}$ from the absorption and emission frequencies, are also given. The regular doublet differences $\ensuremath{\Delta}(\frac{\ensuremath{\nu}}{N})=\frac{({\ensuremath{\nu}}_{{L}_{2}}\ensuremath{-}{\ensuremath{\nu}}_{{L}_{1}})}{N}={L}_{2}\ensuremath{-}{L}_{1}$ are found to agree well with the values calculated from the Sommerfeld formula.The variation of the regular doublet frequency differences ${\mathrm{L}}_{2}$ --- ${\mathrm{L}}_{1}$, ${\mathrm{M}}_{2}$ --- ${\mathrm{M}}_{1}$, ${\mathrm{M}}_{4}$ --- ${\mathrm{M}}_{3}$ with atomic number is given very closely by the series expressions developed by Sommerfeld. For elements of high atomic number, $Z$, these series do not converge very rapidly. For the range of elements mentioned in this paper the empirical expression $\ensuremath{\Delta}(\frac{\ensuremath{\nu}}{N})=K{Z}^{5}$ is found to hold within the experimental limits where $K$ has the following values: 4.44 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}8}$ for ${L}_{2}\ensuremath{-}{L}_{1}$, 1.97 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}9}$ for ${M}_{2}\ensuremath{-}{M}_{1}$, and 9.60 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}9}$ for ${M}_{4}\ensuremath{-}{M}_{3}$.Suggested notation for x-ray emission lines.---Instead of the present conflicting notations, it is suggested that the symbol for each emission line designate the initial and final energy levels; for example the line produced by an electron shifting to the ${L}_{1}$ from the ${M}_{5}$ orbit might be denoted by ${L}_{1}{\ensuremath{\beta}}_{5}$ instead of $\mathrm{Ll}$ or ${L}_{\ensuremath{\epsilon}}$.