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- Cedervall, Johan, et al.
(författare)
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Low temperature magneto-structural transitions in Mn3Ni20P6
- 2016
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Ingår i: Journal of Solid State Chemistry. - : Academic Press Inc.. - 0022-4596 .- 1095-726X. ; 237, s. 343-348
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Tidskriftsartikel (refereegranskat)abstract
- X-ray and neutron powder diffraction has been used to determine the crystal and magnetic structure of Mn3Ni20P6. The crystal structure can be described as cubic with space group Fm3¯m (225) without any nuclear phase transformation within studied temperature interval from room temperature down to 4 K. The magnetic structure of Mn3Ni20P6 is complex with two independent magnetic positions for the Mn atoms and the compound passes three successive magnetic phase transitions during cooling. At 30 K the spins of the Mn atoms on the Wyckoff 4a site (Mn1) order to form a primitive cubic antiferromagnetic structure with propagation vector k=(0 0 1). Between 29 and 26 K the Mn atoms on the Wyckoff 8c site (Mn2) order independently on already ordered Mn1 magnetic structure forming a commensurate antiferromagnetic structure with propagation vector k=(0 0 12) and below 26 K, both Mn positions order to form an incommensurate helical structure with propagation vector k=(0 0 ~0.45). Magnetization vs. temperature curve of Mn3Ni20P6 shows a steep increase indicating some magnetic ordering below 230 K and a sharp field dependent anomaly in a narrow temperature range around 30 K.
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| 2. |
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| 3. |
- Dubrovinsky, L, et al.
(författare)
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Pressure-induced invar effect in Fe-Ni alloys
- 2001
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Ingår i: PHYSICAL REVIEW LETTERS. - 0031-9007. ; 86:21, s. 4851-4854
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the pressure-volume (P-V) relations for cubic iron-nickel alloys for three different compositions: Fe0.64Ni0.36, Fe0.55Ni0.45, and Fe0.20Ni0.80. It is observed that for a certain pressure range the bulk modulus does not change or can even
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| 4. |
- Eriksson, Therese, et al.
(författare)
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Complex magnetic properties of Mn3Ni20P6 and ferromagnetic structure of the new isostructural compound Mn3Pd20P6
- 2007
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 308:2, s. 203-209
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Tidskriftsartikel (refereegranskat)abstract
- A new compound, Mn3Pd20P6, has been synthesized and the crystal and magnetic structures have been determined by neutron powder diffraction. The crystal structure is cubic, with a = 11.9563(2) angstrom, space group Fm (3) over barm, and is isostructural to Mn3Ni20P6, a ternary ordering variant of the Cr23C6-type structure. The magnetic properties of Mn3Pd20P6 and Mn3Ni20P6 were studied by magnetization measurements. For Mn3Pd20P6 a transition, suggested to be of first order, to a ferromagnetic structure takes place at 110 K, whereas the saturation magnetization shows unusual temperature dependence. Magnetization vs. field loops show very weak coercivity, and the magnitude of the saturation magnetization agrees well with parallel Mn magnetic moments on two different sublattices of 4.24(8) mu(B), and 2.88(8) mu(B), respectively, found by neutron powder diffraction at 10 K. Magnetization vs. temperature measurements for Mn3Ni20P6 do not show a well-defined transition temperature, but show signatures of magnetic order with small excess magnetic moments aligned by the applied field below about 240 K. Further, signatures of a spin reorientation process at around 30 K are noted.
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| 5. |
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| 6. |
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| 7. |
- Kindblom, Jenny, 1971, et al.
(författare)
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Increased adipogenesis in bone marrow but decreased bone mineral density in mice devoid of thyroid hormone receptors.
- 2005
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Ingår i: Bone. - : Elsevier BV. - 8756-3282. ; 36:4, s. 607-16
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Tidskriftsartikel (refereegranskat)abstract
- Mice deficient for all known thyroid hormone receptors, TRalpha1-/-beta-/- mice, display a clear skeletal phenotype characterized by growth retardation, delayed maturation of long bones and decreased trabecular and total bone mineral density (BMD; -14.6 +/- 2.8%, -14.4 +/- 1.5%). The aim of the present study was to investigate the molecular mechanisms behind the skeletal phenotype in TRalpha1-/-beta-/- mice. Global gene expression analysis was performed on total vertebrae from wild-type (WT) and TRalpha1-/-beta-/- mice using DNA microarray and the results were verified by real-time PCR. The mRNA levels of six genes (AdipoQ, Adipsin, Fat-Specific Protein 27 (FSP 27), lipoprotein lipase (LPL), retinol-binding protein (RBP) and phosphoenolpyruvate carboxykinase (PEPCK)) expressed by mature adipocytes were increased in TRalpha1-/-beta-/- compared with WT mice. An increased amount of fat (225% over WT) due to an increased number but unchanged mean size of adipocytes in the bone marrow of TRalpha1-/-beta-/- mice was revealed. Interestingly, the mRNA levels of the key regulator of osteoclastogenesis, receptor activator of NF-varkappab ligand (RANKL), were dramatically decreased in TRalpha1-/-beta-/- mice. In conclusion, TRalpha1-/-beta-/- mice demonstrated increased expression of adipocyte specific genes and an increased amount of bone marrow fat. Thus, these mice have increased adipogenesis in bone marrow associated with decreased trabecular bone mineral density (BMD). One may speculate that these effects either could be caused by an imbalance in the differentiation of the osteoblast and the adipocyte lineages at the expense of osteoblastogenesis, or by independent effects on the regulation of both osteoblastogenesis and adipogenesis.
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| 8. |
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| 9. |
- Vennström, Marie
(författare)
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Crystal Chemistry of the Ti3Sn-D, Nb4MSi-D and Pd-Ni-P Systems
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Future energy systems based on hydrogen as energy carrier require reliable ways for storing hydrogen gas in safe, clean and efficient ways. Metal hydrides absorb hydrogen gas reversibly, making them suitable for storage applications. Investigations of the crystal structures of these materials contribute to an understanding of the factors which can influence the absorption. Three systems, Ti3Sn-D, Nb4MSi-D (M=Co or Ni) and Pd-Ni-P, have been investigated in this thesis. Various solid state synthesis techniques have been used for sample preparation. The crystal structures have been studied using x-ray and neutron diffraction techniques. Three metal hydride phases were found in the Ti3Sn-D system upon hydrogenation. Deuterium occupies titanium octahedra and the applied deuterium pressure induces the phase transitions. The distances between the deuterium atoms increase from 2.47 Å in orthorhombic Ti3SnD0.80 to 4.17 Å in cubic Ti3SnD. The Nb4MSi-D system (M=Co or Ni) readily absorbs deuterium at room temperature and 90 kPa deuterium pressure to give a deuterium content of Nb4MSiD~2.5. Two interstitial voids, both coordinated by four niobium atoms arranged in a tetrahedral configuration, accommodate deuterium atoms. Two ternary phases and a solid solution of nickel in Pd3P have been synthesised and the crystal structures determined. PdNi2P is orthorhombic and crystallises in the MgCuAl2-type structure: an ordered derivative of the Re3B-type structure. Pd8Ni31P16 is a tetragonal high-temperature phase stable at 700°C with 110 atoms in the unit cell. Pd2.7Ni0.3P0.94 has the cementite-type structure with mixed occupancy of palladium and nickel at one of the two non-equivalent crystallographic metal positions.
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| 10. |
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