| 1. |
- Kotlov, A., et al.
(författare)
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Excited states of molybdenum oxyanion in scheelite and wolframite structures
- 2007
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1350-4487 .- 1879-0925. ; 42:4-5, s. 767-770
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Tidskriftsartikel (refereegranskat)abstract
- Scheelite CdMoO4 and wolframite eCdWO(4):MO (0.04-0.4wt%) single crystals were studied using the time-resolved spectroscopy under UV excitation over a temperature range of 1.85-300K. The threshold energies for the creation of free charge carriers were measured using the method of photostimulated luminescence. The decay kinetics of the main emission in CdMoO4 and the molybdenum-related emission in CdWO4:MO was studied and the parameters of the triplet excited states of molybdenum-related oxyanions were calculated. (C) 2007 Elsevier Ltd. All rights reserved.
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| 2. |
- Gustafsson, Joacim, et al.
(författare)
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The langbeinite type Rb2TiY(PO4)(3)
- 2006
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Ingår i: Acta Crystallographica Section E: Structure Reports Online. - 1600-5368. ; 62:7, s. i160-i162
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Tidskriftsartikel (refereegranskat)abstract
- Dirubidium titanium yttrium triphosphate belongs to the langbeinite structure type with a framework of Mo-6 octahedra (M = Ti, Y) sharing corners with PO4 tetrahedra and vice versa, creating cages in which the Rb+ cations are located. The compound exhibits mixed Ti/Y populations in the two crystallographically independent octahedral sites of symmetry 3. More than two-thirds of the yttrium is found in one site and the remaining amount in the other; this is caused by the difference in coordination for the two sites.
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| 3. |
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| 4. |
- Gustafsson, Joacim, et al.
(författare)
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Two new phosphate langbeinites, Rb2YbTi(PO4)(3) and Rb2Yb0.32Ti1.68(PO4)(3) investigated at 293 and 150 K
- 2005
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Ingår i: Acta Crystallographica Section C: Crystal Structure Communications. - 0108-2701 .- 1600-5759. ; 61:2, s. i9-i13
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Tidskriftsartikel (refereegranskat)abstract
- The rubidium ytterbium titanium phosphates Rb2YbTi(PO4)(3), ( I), and Rb(2)Yb(0.3)2Ti(1.68)(PO4)(3), (II), have been structurally characterized from X-ray data collected at both 293 and 150 K. Compound ( II) is blue owing to the presence of mixed-valence titanium (41% Ti3+ + 59% Ti4+). Both (I) and (II) belong to the langbeinite structure type, with mixed Yb/Ti populations in the two crystallographically independent octahedral sites ( of symmetry 3). Ytterbium favours one of these sites, where about two-thirds of the Yb atoms are found. The O-atom displacement parameters are large in both compounds at both temperatures.
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| 5. |
- Öhrström, Lars, 1963, et al.
(författare)
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The pedagogical implications of using MatLab in integrated chemistry and matehamatics courses
- 2005
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Ingår i: International journal of engineering education. - 0949-149X. ; 21:4, s. 683-691
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Tidskriftsartikel (refereegranskat)abstract
- The last years the undergraduate chemistry and mathematics courses at Chalmers Tekniska Högskola (Chalmers University of Technology, Sweden) has undergone a major curriculum reform. One of the driving motives behind the reform was that students should learn to use mathematics as a real tool for solving chemical problems. Mathematicians and chemists, with pedagogical help from an educational expert, changed the traditional course structure in terms of organisation, content, and teaching and learning methods. This paper concentrates on the use of MATLAB in laboratory work and in individual and group assignments. It deals, in particular, with the pedagogical benefits that the designers of the new course saw in presenting real chemical problems that could be solved using applied mathematics and the MATLAB software. Student experience was evaluated both by the teachers and the educational consultant and responses are largely positive. Increased student learning can be seen through higher motivation and synergy effects of treating chemical problems in the MATLAB tutorials. The most serious problem is to give all students the necessary MATLAB skills and a risk is an overestimation of the MATLAB proficiency in subsequent courses leading to un-proportional workload on projects and little time for reading and study.
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| 6. |
- Norberg, Stefan, 1972, et al.
(författare)
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A TiP2O7 superstructure
- 2001
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Ingår i: Acta Crystallographica Section C: Crystal Structure Communications. - 0108-2701 .- 1600-5759. ; 57:3, s. 225-227
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Tidskriftsartikel (refereegranskat)abstract
- A room-temperature structural model of titanium pyrophosphate, TiP2O7, has been determined from synchrotron X-ray data. The structure consists of TiO6 octahedra and PO4 tetrahedra sharing corners in a three-dimensional network. The PO4 tetrahedra form P2O7 groups connecting the TiO6 octahedra. The 3 x 3 x 3 superstructure differs substantially from the parent AB(2)O(7) structure. The P-O-P bonding angles of the pyrophosphate group are between 141.21 (12) and 144.51 (13)degrees for those groups not located on the threefold axis. The individual TiO6 octahedra and PO4 tetrahedra are somewhat distorted.
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| 7. |
- Norberg, Stefan, 1972, et al.
(författare)
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Dopant positions in strontium/chromium- and barium-doped KTP, determined with synchrotron X-radiation
- 2001
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Ingår i: Acta Crystallographica Section B: Structural Science. - 0108-7681 .- 1600-5740. ; 56:6, s. 980-987
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Tidskriftsartikel (refereegranskat)abstract
- Structure factors for strontium/chromium- (Sr/Cr) and barium- (Ba) doped potassium titanyl phosphate (KTiOPO4, KTP) were measured with focused synchrotron X-radiation [0.75000 (9) Angstrom] using a fast avalanche photodiode counter. Space group Pna2(1), Z = 8,a = 12.786 (2), b = 6.3927 (8), c = 10.5585 (9) Angstrom, T = 293 (1) K, R = 0.028 (SrCrKTP); a = 12.851 (6), b = 6.418 (3), c = 10.620 (5) Angstrom, T = 120 (1) K, R = 0.031 (BaKTP). The refinement of the dopant positions showed that Ba2+ is positioned in the larger of the two K cavities of KTP, while the smaller Sr2+ ion is located in both. Split positions are found for the strontium dopant in both cavities and they are located in the positive c direction from the potassium cation. The chromium dopant has two different oxidation states, namely +III and +VI; in both states the dopant is located inside the TiO6 octahedra. The two structures show slightly less distorted TiO6 octahedra than pure KTP.
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| 8. |
- Norberg, Stefan, 1972, et al.
(författare)
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KSbO(Ge0.32Si0.68)O-4, a KTP isomorph
- 2001
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Ingår i: Acta Crystallographica Section C: Crystal Structure Communications. - 0108-2701 .- 1600-5759. ; 57:5, s. 510-512
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Tidskriftsartikel (refereegranskat)abstract
- A structural model of potassium antimony germanate/silicate (0.32/0.68), KSbO(Ge0.32Si0.68)O-4, has been determined at room temperature. KSbO(Ge0.32Si0.68)O-4 belongs to the KTiOPO4 (KTP) isomorphic family and is composed of SbO6 octahedra (site symmetry (1) over bar and 2) arranged in helical chains bridged by (Ge/Si)O-4 tetrahedra. Germanium and silicon have a similar distribution in the crystallographically independent tetrahedra (site symmetry 2). The structure contains large cavities occupied by the K atom. Two partially occupied potassium positions have been identified 1.273 (8) Angstrom apart, with an indication of a third potassium position between them. At room temperature, KSbO(Ge0.32Si0.68)O-4 crystallizes in the paraelectric phase of space group Pnan. This phase is found at elevated temperatures for almost all KTiOPO4 isomorphic compounds and KSbO(Ge0.32Si0.68)O-4 is the second isomorph that is paraelectric at room temperature.
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| 9. |
- Öhrström, Lars, 1963, et al.
(författare)
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On the structures and properties of Cr(DMSO)(6)(3+) and the coordination polymer cis-Cr(III)(oxalate)(2)(DMSO)(2) K(DMSO)(2) (n)
- 2000
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Ingår i: Inorganica Chimica Acta. ; 305:2, s. 157-162
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Tidskriftsartikel (refereegranskat)abstract
- cis-Cr(III)(oxalate)(2)(DMSO)(2)K(DMSO)(2) was formed by K3Cr(oxalate), in dimethylsulfoxide-THF mixtures. The structure is ribbon-like with cis-Cr(oxalate)(2)(DMSO)(2)(-) complex ions bridged by oxalates to (DMSO)K(DMSO)(2)K(DMSO) units forming interconnected rings of six metal complexes. In the same type of solutions Cr(DMSO)(6)(NO3)(3) was also formed. In this structure Cr(III) is six-coordinated by oxygens from DMSO. Cr(DMSO)(6)(NO3)(3) is isostructural with Fe(DMSO)(6)(NO3)(3) (J.R. Tzou et al., Acta Crystallogr., Sect. C, 51 (1995) 2249). The Cr(III)-O distance shows an expected shortening of about 0.04 Angstrom compared to the Fe(III)-O bond in Fe(DMSO)(6)(NO3)(3). (C) 2000 Elsevier Science S.A. All rights reserved.
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| 10. |
- Norberg, Stefan, 1972, et al.
(författare)
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Lead(II) oxydiacetate hydrate
- 1999
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Ingår i: Acta Crystallographica Section C: Crystal Structure Communications. - 0108-2701 .- 1600-5759. ; 55:3, s. 356-358
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Tidskriftsartikel (refereegranskat)abstract
- The coordination polyhedron around the Pb atom in the title compound, poly[aqualead(II)-mu(5)-oxydiacetato], [Pb(mu(5)-C4H4O5)(H2O)](n), is a distorted square antiprism formed by three O atoms from one oxydiacetate ligand, four O atoms from four other identical ligands and one water O atom, resulting in a three-dimensional network structure. The almost planar oxydiacetate ligand is disordered over two positions. The Pb lone-pair 6s(2) electrons show stereochemical activity in the coordination sphere.
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