| 1. |
- Azad, Abul Kalam, 1966, et al.
(författare)
-
Synthesis, structural and magnetic characterisation of the double perovskite A(2)MnMoO(6) (A = Ba, Sr)
- 2004
-
Ingår i: Journal of Alloys and Compounds. - 0925-8388. ; 364:1-2, s. 77-82
-
Tidskriftsartikel (refereegranskat)abstract
- A study of the crystallographic structure and magnetic properties of the double perovskites Ba2MnMoO6 and Sr2MnMoO6 in polycrystalline form has been carried out by means of neutron powder diffraction (NPD) and magnetization measurements. The Rietveld analysis of room temperature data shows that the Mn2+ and Mo6+ ions are B-site ordered, i.e. the structure is a NaCl-type ordered double perovskite. Ba2MnMoO6 crystallizes in the cubic space group Full-size image (<1 K) (a=8.1680(1)) and Sr2MnMoO6 crystallizes in the space group P42/n (a=7.9575(5), c=7.9583(9)). Bond valence sum (BVS) calculation revealed that these compounds have the valency pair of {Mn2+(3d5;t32ge2g), Mo6+(4d0)}. The magnetic measurements suggest that these compounds transform to an antiferromagnetic state below 10 K.
|
|
| 2. |
- Quinet, P, et al.
(författare)
-
Radiative lifetime measurements and transition probability calculations in lanthanide ions
- 2002
-
Ingår i: Journal of Alloys and Compounds. - 0925-8388. ; 344:1-2, s. 255-259
-
Tidskriftsartikel (refereegranskat)abstract
- We have undertaken a systematic investigation of spectroscopic properties of lanthanide ions (Z=57-71). Using time-resolved laser-induced fluorescence following one- or two-photon excitations, a large number of radiative lifetimes have been measured at the Lund Laser Centre for singly, doubly and trebly ionized atoms. These new measurements have been used for testing theoretical calculations performed within the framework of a relativistic Hartree-Fock approach taking core-polarization effects into account. Using the experimental lifetimes (when available) and the theoretical branching fractions, a large number of transition probabilities, most of them of astrophysical interest, have been deduced and are stored in a new database (DREAM). Up to now, the results obtained concern the following ions: La2+, Ce2+, Ce2+, Pr2+, Ho2+, Er2+, Tm2+, Tm2+, Yb2+, Yb2+, Yb2+, Lu2+ and Lu2+. (C) 2002 Elsevier Science B.V. All rights reserved.
|
|
| 3. |
- Schmitt, T, et al.
(författare)
-
Resonant soft X-ray emission spectroscopy of doped and undoped vanadium oxides
- 2004
-
Ingår i: Journal of Alloys and Compounds. - 0925-8388 .- 1873-4669. ; 362:1-2, s. 143-150
-
Tidskriftsartikel (refereegranskat)abstract
- Resonant soft X-ray emission (RSXE) spectra of NaV2O5, MoxV1-xO2 and V2O3 have been recorded for a series of excitation energies at resonances of the V L- and O K-absorption band. Resonant excitation allows us, firstly, to separate V 3d and O 2p projected density-of-states of the valence band and, secondly, to study charge-neutral low-energy excitations due to resonant inelastic X-ray scattering (RIXS). We found that both the V L- and the O K-emission spectra clearly show components originating from O 2p- and V 3d-states, reflecting the high degree of hybridization of the valence band in all compounds. At threshold excitation we observed that NaV2O5 spectra are dominated by RIXS whereas MoxV1-xO2 and V2O3 spectra show bandlike features, which may be due to differences in the correlation effects of the compounds. We compared the RSXE spectra with cluster model calculations, which gives a good account for NaV2O5 whereas the RSXE spectra of the other compounds show RIXS only at certain energies well above the threshold. In fact, we interpret the trend in the RSXE spectra of the MoxV1-xO2 compound system as a successive filling of the (rigid) V 3d band with increasing Mo content. (C) 2003 Elsevier B.V. All rights reserved.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Edvardsson, Sverker, et al.
(författare)
-
The energy matrix using determinantal product states applied to Ho:YAG
- 2000
-
Ingår i: Journal of Alloys and Compounds. - 0925-8388 .- 1873-4669. ; 303-304, s. 280-284
-
Tidskriftsartikel (refereegranskat)abstract
- A program written in C is applied for calculations of energy levels and wavefunctions of the lanthanides or actinides. Standard non-relativistic phenomenological operators are used. Simple determinantal product states are used to form the basis set. The complete energy matrix is diagonalized with all operators interacting simultaneously thus allowing mixing of all quantum numbers. The crystal field splitting can also be studied via the standard crystal field hamiltonian as well as the magnetic field influence on the energy levels. The program is here applied to the technologically interesting trivalent ion holmium which is used to form extremely strong magnets as well as the medical eye-safe laser Ho:YAG. Both experimentally fitted and calculated self-consistent crystal field parameters are used to study the energy structure. Crystal ionic polarizabilities with electron correlation included are partly calculated. Zeeman split levels are also studied.
|
|
| 7. |
- El-Mahallawy, N., et al.
(författare)
-
On the reaction between aluminum, K2TiF6 and KBF4
- 1999
-
Ingår i: Journal of Alloys and Compounds. - 0925-8388 .- 1873-4669. ; 292:1-2, s. 221-229
-
Tidskriftsartikel (refereegranskat)abstract
- The reaction between molten Al and KBF4 and K2TiF6 was analyzed. Additions of the two salts separately, consecutively and simultaneously were made at 800 and 1000 °C. The phases formed were identified and their morphology investigated. When adding K2TiF6 emulsification of the salt occurs. Residual salt containing K, Ti, Al and O was found in addition to slag containing K, Al and O. In an emulsified region, a new globular morphology of Al3Ti-type was found. No evidence of emulsification of KBF4 was found. This implies that the two salts react individually with Al. A new morphology of AlB2, in the form of thin plates, formed presumably at the salt/aluminum interface, was also found.
|
|
| 8. |
|
|
| 9. |
- Godlewski, M., et al.
(författare)
-
Mn2+ intra-shell recombination in bulk and quantum dots of II-VI compounds
- 2002
-
Ingår i: Journal of Alloys and Compounds. - 0925-8388 .- 1873-4669. ; 341:1-2
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Origin of a fast component of the photoluminescence (PL) decay of Mn 2+ intra-shell 4T1 ? 6A 1 transition in bulk and quantum dot structures is discussed based on the results of PL, PL kinetics and optically detected magnetic resonance experiments. It is demonstrated that a fast component of the PL decay, reported previously for quantum dot structure and related to quantum confinement effects, is also observed in bulk samples and is very much enhanced upon generation of free carriers. The appearance of this fast component of the PL decay is related to a very efficient spin cross-relaxation between localized spins of Mn ions and spins of free carriers. © 2002 Elsevier Science B.V. All rights reserved.
|
|
| 10. |
- Hillert, M., et al.
(författare)
-
Point defects in B2 compounds
- 2001
-
Ingår i: Journal of Alloys and Compounds. - 0925-8388 .- 1873-4669. ; 329:02-jan, s. 208-213
-
Tidskriftsartikel (refereegranskat)abstract
- Point defects in B2 compounds are described with a model based on the formula (A,B,Va),(B,A,Va), and results are compared with previous results from two models based on combined defects and using the formulae (A,B), (B,A), and (A,Va)(1) (B,A)(1) The comparison is straight-forward close to the stoichiometric composition but not closer to the pure elements. Using the more general model, it is demonstrated that the fact that vacancies are the predominant defect in some B2 compounds with a small excess of B atoms depends primarily on interactions between next-nearest neighbours rather than on a high enthalpy of formation of the compound, as proposed earlier.
|
|
