Source:http://linkedlifedata.com/resource/pubmed/id/18459766
| Subject | Predicate | Object | Context |
|---|---|---|---|
| pubmed-article:18459766 | rdf:type | pubmed:Citation | lld:pubmed |
| pubmed-article:18459766 | lifeskim:mentions | umls-concept:C0025552 | lld:lifeskim |
| pubmed-article:18459766 | lifeskim:mentions | umls-concept:C0030015 | lld:lifeskim |
| pubmed-article:18459766 | lifeskim:mentions | umls-concept:C0444626 | lld:lifeskim |
| pubmed-article:18459766 | lifeskim:mentions | umls-concept:C0016770 | lld:lifeskim |
| pubmed-article:18459766 | lifeskim:mentions | umls-concept:C1414863 | lld:lifeskim |
| pubmed-article:18459766 | lifeskim:mentions | umls-concept:C0439148 | lld:lifeskim |
| pubmed-article:18459766 | lifeskim:mentions | umls-concept:C0024488 | lld:lifeskim |
| pubmed-article:18459766 | lifeskim:mentions | umls-concept:C0563532 | lld:lifeskim |
| pubmed-article:18459766 | lifeskim:mentions | umls-concept:C2699782 | lld:lifeskim |
| pubmed-article:18459766 | lifeskim:mentions | umls-concept:C0871161 | lld:lifeskim |
| pubmed-article:18459766 | pubmed:issue | 11 | lld:pubmed |
| pubmed-article:18459766 | pubmed:dateCreated | 2008-5-28 | lld:pubmed |
| pubmed-article:18459766 | pubmed:abstractText | The rare-earth metal(III) oxide selenides of the formula La4O4Se[Se2], Ce4O4Se[Se2], Pr4O4Se[Se2], Nd4O4Se[Se2], and Sm4O4Se[Se2] were synthesized from a mixture of the elements with selenium dioxide as the oxygen source at 750 degrees C. Single crystal X-ray diffraction was used to determine their crystal structures. The isostructural compounds M4O4Se[Se2] (M=La, Ce, Pr, Nd, Sm) crystallize in the orthorhombic space group Amm2 with cell dimensions a=857.94(7), b=409.44(4), c=1316.49(8) pm for M=La; a=851.37(6), b=404.82(3), c=1296.83(9) pm for M=Ce; a=849.92(6), b=402.78(3), c=1292.57(9) pm for M=Pr; a=845.68(4), b=398.83(2), c=1282.45(7) pm for M=Nd; and a=840.08(5), b=394.04(3), c=1263.83(6) pm for M=Sm (Z=2). In their crystal structures, Se2- anions as well as [Se-Se]2- dumbbells interconnect {[M4O4]4+} infinity 2 layers. These layers are composed of three crystallographically different, distorted [OM4]10+ tetrahedra, which are linked via four common edges. The compounds exhibit strong Raman active modes at around 215 cm(-1), which can be assigned to the Se-Se stretching vibration. Optical band gaps for La4O4Se[Se2], Ce4O4Se[Se2], Pr4O4Se[Se2], Nd4O4Se[Se2], and Sm4O4Se[Se2] were derived from diffuse reflectance spectra. The energy values at which absorption takes place are typical for semiconducting materials. For the compounds M4O4Se[Se2] (M=La, Pr, Nd, Sm) the fundamental band gaps, caused by transitions from the valence band to the conduction band (VB-CB), lie around 1.9 eV, while for M=Ce an absorption edge occurs at around 1.7 eV, which can be assigned to f-d transitions of Ce3+. Magnetic susceptibility measurements of Ce4O4Se[Se2] and Nd4O4Se[Se2] show Curie-Weiss behavior above 150 K with derived experimental magnetic moments of 2.5 micro B/Ce and 3.7 micro B/Nd and Weiss constants of theta p=-64.9 K and theta p=-27.8 K for the cerium and neodymium compounds, respectively. Down to 1.8 K no long-range magnetic ordering could be detected. Thus, the large negative values for theta p indicate the presence of strong magnetic frustration within the compounds, which is due to the geometric arrangement of the magnetic sublattice in form of [OM4]10+ tetrahedra. | lld:pubmed |
| pubmed-article:18459766 | pubmed:language | eng | lld:pubmed |
| pubmed-article:18459766 | pubmed:journal | http://linkedlifedata.com/r... | lld:pubmed |
| pubmed-article:18459766 | pubmed:status | PubMed-not-MEDLINE | lld:pubmed |
| pubmed-article:18459766 | pubmed:month | Jun | lld:pubmed |
| pubmed-article:18459766 | pubmed:issn | 0020-1669 | lld:pubmed |
| pubmed-article:18459766 | pubmed:author | pubmed-author:DorhoutPeter... | lld:pubmed |
| pubmed-article:18459766 | pubmed:author | pubmed-author:SchleidThomas... | lld:pubmed |
| pubmed-article:18459766 | pubmed:author | pubmed-author:ChoudhuryAmit... | lld:pubmed |
| pubmed-article:18459766 | pubmed:author | pubmed-author:StrobelSabine... | lld:pubmed |
| pubmed-article:18459766 | pubmed:author | pubmed-author:LippChristian... | lld:pubmed |
| pubmed-article:18459766 | pubmed:issnType | lld:pubmed | |
| pubmed-article:18459766 | pubmed:day | 2 | lld:pubmed |
| pubmed-article:18459766 | pubmed:volume | 47 | lld:pubmed |
| pubmed-article:18459766 | pubmed:owner | NLM | lld:pubmed |
| pubmed-article:18459766 | pubmed:authorsComplete | Y | lld:pubmed |
| pubmed-article:18459766 | pubmed:pagination | 4936-44 | lld:pubmed |
| pubmed-article:18459766 | pubmed:year | 2008 | lld:pubmed |
| pubmed-article:18459766 | pubmed:articleTitle | Rare-earth metal(III) oxide selenides M4O4Se[Se2] (M=La, Ce, Pr, Nd, Sm) with discrete diselenide units: crystal structures, magnetic frustration, and other properties. | lld:pubmed |
| pubmed-article:18459766 | pubmed:affiliation | Institute for Inorganic Chemistry, Universitaet Stuttgart, Stuttgart, Germany. | lld:pubmed |
| pubmed-article:18459766 | pubmed:publicationType | Journal Article | lld:pubmed |