Werner Urland Explained

Werner Urland
Birth Date:13 April 1944

Werner Urland (born 13 April 1944) is a German chemist whose name is imprinted in the pioneering implementation of the Angular Overlap Model (AOM: a specific paradigm for accounting metal ions in complexes or crystals [1] [2] [3]) for the interpretation of optical and magnetic properties of rare-earth coordination compounds.[4] [5] [6] This approach receives a renewed value in the context of the vogue around the lanthanide-based new materials, such as achieving magnets at molecular scale,[7] [8] [9] or designing new phosphor materials.[10]

Biography

Werner Urland was born in Berlin on 13 April 1944. Between 1963 and 1968 he studied and graduated in chemistry in Giessen, Germany. The interval 1968-1971 was dedicated to the work of a doctoral thesis, under the supervision of Professor R. Hoppe, on ternary oxides of noble metals. The PhD stage incorporated a scholarship at University College in London, in the group of Dr. Malcolm Gerloch under the supervision of Professor Lord Jack Lewis (Jack Lewis, Baron Lewis of Newnham, where the acquaintance with the magnetic properties and specific models of coordination compounds had defined a turning point in his career. The following post-doctoral stage (1971-1974) in preparative solid-state chemistry and the return to England, at Cambridge, in the theory group directed by Prof. A. D. Buckingham, contoured an original composition of scientific interests, at the confluence of applied chemistry with the theoretical insight, aiming for understanding and predicting useful properties.Assimilating the different formation sources, Werner Urland contoured his original perspective in the magnetochemistry of rare earth compounds, the domain delineated by his habilitation treatise (1975-1980).

Between 1982 and 1986 he occupied a research position at the Max Planck Institute for Solid State Research in Stuttgart. Since 1986 he has been appointed professor in Hanover, where he acted till his retirement in 2007, on a chair dedicated to special topics of inorganic chemistry. In 1996 he declined an invitation to occupy a position as professor of inorganic chemistry at the University of Vienna. Since 2011, Werner Urland occupies a senior researcher position on grants, in the group of theoretical and computational chemistry of Professor Claude Daul, at University of Fribourg, Switzerland. Presently, Werner Urland is dealing with setting up an institute in Muralto/Locarno, Switzerland, with the help of the "Fondazione Sciaroni", dedicated to theoretical approach of material sciences and property design, thus supporting experimental work by universities and industries.

Activity

Preparative solid state and coordination chemistry

In the branch dedicated to solid state chemistry, Werner Urland et al. synthesized and characterized structurally, by X-Ray crystallography, several lanthanide-chalcogenide systems with unusual anionic structures, such as PrSe2, PrSe1.9−x, CeSe1.9−x NdSe1.9 [11] [12] [13] [14] or more complex compositions, such as chalcogenide-silicates like Nd2 SeSiO4 like M 4X 3 [Si<sub>2 </sub>O<sub> 7</sub>] (M = Ce - Er; X = S, Se) [15] [16] The crystal structures of prototypic chalcogenides of trivalent lanthanides, like Ln2Se3 (Ln=Sm, Tb, Ho) were resolved.,[17] [18] treating also their polymorphic manifestations [19] and the electronic structure.[20] Other solid phase systems such as lanthanide aluminium halides, LnAl3X12 (with Ln = lanthanide trivalent ions in the La-Ho series and X= Cl, Br) were considered as synthetic and structural problems.[21] [22] Another area of Werner Urland's research was contoured around the special properties of condensed systems, such as superconductivity of mixed oxide compounds, [23] [24] or ionic conductivity and dynamics of sodium and lanthanide ions in crystals like Na+/Ln3+-ß"-Al2O3 [25] [26] [27] The same systems received attention also in the respect of their magnetic properties, in relation with the determinant structural factors.[28] [29] Among other approached special properties, one may mention the treatment of bipolaron absorption in Ba1−xKxBiO3 and Ba0.6K0.4−xBiO3 materials.[30]

Modelling breakthroughs

After a brief apprenticeship in applying standard versions of ligand field modelling to transition metal complexes, tackling single-crystal polarized spectra and magnetic anisotropy of Ni(II) and Co(II) complexes in the less usual five-coordination states,[31] Werner Urland conceived his own "trademark" devising a ligand-field potential for f electrons in the frame of Angular Overlap Model.[32] Immediate applications clarified the meaning of the parameters, taking rare-earth hydroxides and chlorides as case studies.[33] [34] Many papers developed in this domain were single authored, marking the original perspective of Werner Urland. Briefly, describing the situation of Ligand field theory, practically equivalent to Crystal Field Theory pointing that this method is more popular, often invoked in qualitative respects, for transition metal systems (coordination and solid phase compounds) [35] while for f-elements (lanthanide and actinide compounds) it is regarded as a rather specialized field, due to somewhat more complicated technical stances.[36] A conceptual drawback is the lack of chemical intuitiveness of the parameters of classical ligand field theories. There are several conventions, such as Wybourne or Stevens parameterizations [37] [38] An alternate offer was identified in the Angular Overlap Model basically developed for d-type transition metal systems [39] [40] [41] It is the merit of Werner Urland for stating the AOM version for f-type compounds, advocating for it by systematic applications acting as proof for the validity of this approach. The theoretical activity was complemented by involvement in synthetic coordination chemistry, producing new coordination compounds taken as relevant new case studies for ligand field interpretation of magnetic properties. A series consisting in individual octahedral units [LnCl<sub>6</sub>]3−,[42] [43] [44] is interesting by the intrinsic simplicity of these complexes, once is known that lanthanide complexes are usually adopting higher coordination numbers, the hexa-coordination being enforced mostly by the doping regime, in solid lattices, such as elpasolites (a variety of Halide minerals with ABM2X3 stoichiometry). The magnetic properties of [LnCl<sub>6</sub>]3− complexes (with pyridinium counter ions) were analysed in the non-trivial details of the causal role of the ligand field effects. In the same spirit, a detailed attention was devoted to the relatively simple lanthanide pentakis nitrato complexes, starting from the synthesis stage [45] continued into the instrumental and theoretical characterization. The Electron paramagnetic resonance (EPR) spectra of the pentakis nitrato ytterbate(III), [Yb(NO<sub>3</sub>)<sub>5</sub>]2− [46] was recorded and modelled, the ligand field treatment being based also on advanced neutron spectroscopy measurements.[47] A peculiar manifestation, discovered in the light of the developed methodologies, was the first report of level crossing in ligand field diagrams, tuned by external pressure.[48] [49] [50] A systematic attention was devoted to the magnetism determined by lanthanide ions in solid compounds like the ternary oxides, CsLnO2 [51] [52] or Cs2MLnX6 elpasolite type systems, with various combination of (M = Na, K, Rb) alkaline metal ions and (X=F, Cl, Br) halides, for several Ln(III) rare earth cases.[53] [54] [55] Werner Urland proved the ligand field as the determinant for the pattern of magnetic susceptibility dependences on temperature, often mistakenly attributed to inter-center exchange coupling.A distinct branch of investigation concerned the unusual ferromagnetic Gd(III)-Gd(III) exchange coupling recorded in newly synthesized homo-polynuclear complexes of gadolinium with various carboxylates (acetate, fluoro- and chloro- substituted acetate) as bridging ligand.[56] [57] [58]

Recent advances

Following the retirement in 2007 from Hannover professorship, Werner Urland resumed the scientific activity as guest senior researcher in the group of Professor Claude Daul at University of Fribourg (Switzerland), where he proposed a topic related to the so-called "Warm-White Light", namely the improvement of blue-type Light-emitting diodes (LEDs) towards the better resemblance to the sunlight spectrum by coating with appropriate phosphors based on lanthanide doped materials. The topic represents a hot relevance in the context of the trends of eliminating traditional incandescent light bulbs, for the sake of energy saving new technologies . This technological challenge is underlined by the award of the 2014 Nobel Prize in Physics "for the invention of efficient blue light-emitting diodes, which has enabled bright and energy-saving white light sources" to Shuji Nakamura, Isamu Akasaki and Hiroshi Amano and by the declaration of 2015 as International Year of Light and Light-based Technologies, (IYL 2015). Hybridizing Werner's Urland expertise in experimental and theoretical aspects of rare earth materials with a computation and analysis methodology due to C. Daul and M. Atanasov,[59] altogether with methodological knowledge of external collaborators of the group, a series of works was produced, dealing with the analysis and prediction form first principles of the key factors in the luminescence of relevant lanthanide ions in various environments.[60] [61] [62] [63] [64] The modelling is based on a set of algorithmic steps abbreviated as LFDFT,[65] consisting in non-routine calculations in the frame of Density Functional Theory (DFT) followed by the analysis in the frame of Ligand Field Theory. The issue of first principles calculations on rare-earth systems is non-trivial, because of special features of the f-shell, such as the shielded and weakly interacting nature, that poses technical and conceptual difficulties, in relation to modern methods of quantum chemistry.[66] The specific problem of the modelling the luminescence of rare-earth systems called the need of extending the ligand field phenomenology, from its one-shell status (dedicated to d or f electrons) to a two-shell Hamiltonian (quantum mechanics), comprising simultaneously the d and f shells, because the involved optical transitions have inter-shell nature. Also recently, Werner Urland, entered the terrain of actinide chemistry, explaining intriguing magnetic behaviour due strong ligand field on uranium(IV) ions in thiophosphates and silicates.[67] [68] The whole deal underlines the validity and renewed value of Werner Urland's early ideas about the theoretical and practical aspects emerging from the chemistry and physics of f-elements.

References

  1. Schäffer . Claus E. . Jørgensen . Chr. Klixbüll . The angular overlap model, an attempt to revive the ligand field approaches . Molecular Physics . Informa UK Limited . 9 . 5 . 1965 . 0026-8976 . 10.1080/00268976500100551 . 401–412. 1965MolPh...9..401S .
  2. Book: Hoggard, Patrick E. . Structure and Bonding . Optical Spectra and Chemical Bonding in Inorganic Compounds. Angular Overlap Model Parameters . Springer Berlin Heidelberg . Berlin, Heidelberg . 2004 . 978-3-540-00853-8 . 0081-5993 . 10.1007/b11304 . 37–57. 106.
  3. T. Schönherr, M. Atanasov, H. Adamsky, Angular Overlap Model, in A. B. P. Lever, J. A. McCleverty, T. J. Meyer (Eds.) Comprehensive coordination chemistry II, Vol. 2. Elsevier, Oxford, 2003, pp. 443-455.
  4. Urland . W. . On the ligand-field potential for f electrons in the angular overlap model . Chemical Physics . Elsevier BV . 14 . 3 . 1976 . 0301-0104 . 10.1016/0301-0104(76)80136-x . 393–401. 1976CP.....14..393U .
  5. Urland . W. . The application of the angular overlap model in the calculation of paramagnetic principal susceptibilities for f -electron systems . Chemical Physics Letters . Elsevier BV . 46 . 3 . 1977 . 0009-2614 . 10.1016/0009-2614(77)80627-1 . 457–460. 1977CPL....46..457U .
  6. Urland . W. . The assessment of the crystal-field parameters for fn-electron systems by the angular overlap model rare-earth ions m3+ in limf4 and substituted in liyf4 . Chemical Physics Letters . Elsevier BV . 77 . 1 . 1981 . 0009-2614 . 10.1016/0009-2614(81)85599-6 . 58–62. 1981CPL....77...58U .
  7. Tang . Jinkui . Hewitt . Ian . Madhu . N. T. . Chastanet . Guillaume . Wernsdorfer . Wolfgang . Anson . Christopher E. . Benelli . Cristiano . Sessoli . Roberta . Powell . Annie K. . Dysprosium Triangles Showing Single-Molecule Magnet Behavior of Thermally Excited Spin States . Angewandte Chemie International Edition . Wiley . 45 . 11 . 6 March 2006 . 1433-7851 . 10.1002/anie.200503564 . 1729–1733. 16496432 .
  8. Costes . Jean-Pierre . Dahan . Françoise . Wernsdorfer . Wolfgang . Heterodinuclear Cu−Tb Single-Molecule Magnet . Inorganic Chemistry . American Chemical Society (ACS) . 45 . 1 . 2006 . 0020-1669 . 10.1021/ic050563h . 5–7. 16390033 .
  9. Cimpoesu . Fanica . Dahan . Françoise . Ladeira . Sonia . Ferbinteanu . Marilena . Costes . Jean-Pierre . Chiral Crystallization of a Heterodinuclear Ni-Ln Series: Comprehensive Analysis of the Magnetic Properties. . Inorganic Chemistry . American Chemical Society (ACS) . 51 . 21 . 21 March 2012 . 0020-1669 . 10.1021/ic3001784 . 11279–11293. 22435341 .
  10. Jüstel . Thomas . Nikol . Hans . Ronda . Cees . New Developments in the Field of Luminescent Materials for Lighting and Displays . Angewandte Chemie International Edition . Wiley . 37 . 22 . 4 December 1998 . 1433-7851 . 10.1002/(sici)1521-3773(19981204)37:22<3084::aid-anie3084>3.0.co;2-w . 3084–3103. 29711319 .
  11. P. . Plambeck-Fischer. W. . Urland. W. . Abriel. Zeitschrift für Kristallographie. 1987. 178. 182. Synthesis of PrSe2 and studies of single-crystal structure.
  12. P.. Plambeck-Fischer. W.. Urland. W.. Abriel. Crystal-structure of CeSe1.9−x and PreSe1.9−x. 1988. 182 . 208. Zeitschrift für Kristallographie.
  13. Plambeck-Fischer . P. . Abriel . W. . Urland . W. . Preparation and crystal structure of RESe1.9 (RE=Ce, Pr) . Journal of Solid State Chemistry . Elsevier BV . 78 . 1 . 1989 . 0022-4596 . 10.1016/0022-4596(89)90140-0 . 164–169. 1989JSSCh..78..164P .
  14. Urland . W. . Plambeck-Fischer . P. . Grupe . M. . Darstellung und Kristallstruktur von NdSe1.9. Preparation and Crystal Structure of NdSe1.9 . de. Zeitschrift für Naturforschung B . Walter de Gruyter GmbH . 44 . 3 . 1 March 1989 . 1865-7117 . 10.1515/znb-1989-0303 . 261–264. 98369397 . free .
  15. Grupe . M. . Urland . W. . Darstellung und Kristallstruktur von Nd2SeSiO4 . Preparation and Crystal Structure of Nd2SeSiO4 . Zeitschrift für Naturforschung B . Walter de Gruyter GmbH . 45 . 4 . 1 April 1990 . 1865-7117 . 10.1515/znb-1990-0410 . 465–468. 97491520 . de. free .
  16. Grupe . Matthias . Lissner . Falk . Schleid . Thomas . Urland . Werner . Chalkogenid-Disilicate der Lanthanoide vom Typ M4X3[Si<sub>2</sub>O<sub>7</sub>] (M = Ce-Er; X = S, Se) . Zeitschrift für anorganische und allgemeine Chemie . Wiley . 616 . 10 . 1992 . 0044-2313 . 10.1002/zaac.19926161009 . 53–60 . de.
  17. Grundmeier . Thorsten . Urland . Werner . Zur Kristallstruktur von Tb2Se3 . Zeitschrift für anorganische und allgemeine Chemie . Wiley . 623 . 11 . 1997 . 0044-2313 . 10.1002/zaac.19976231113 . 1744–1746 . de. free .
  18. Urland . Werner . Person . Helmut . Zur Kristallstruktur von Ho2Se3. On the Crystal Structure of Ho2Se3 . Zeitschrift für Naturforschung B . Walter de Gruyter GmbH . 53 . 8 . 1 August 1998 . 1865-7117 . 10.1515/znb-1998-0821 . 900–902. 100943831 .
  19. Grundmeier . Thorsten . Urland . Werner . Zur Polymorphie von Sm2Se3 . Zeitschrift für anorganische und allgemeine Chemie . Wiley . 621 . 11 . 1995 . 0044-2313 . 10.1002/zaac.19956211125 . 1977–1979 . de.
  20. Grundmeier . T. . Heinze . Th. . Urland . W. . On the electronic structure of new ternary selenides of samarium . Journal of Alloys and Compounds . Elsevier BV . 246 . 1–2 . 1997 . 0925-8388 . 10.1016/s0925-8388(96)02466-8 . 18–20.
  21. Hake . D. . Urland . W. . Darstellung und Kristallstruktur von LnAl3Cl12 (Ln = Tb, Dy, Ho) und thermischer Abbau zu LnCl3 . Zeitschrift für anorganische und allgemeine Chemie . Wiley . 586 . 1 . 1990 . 0044-2313 . 10.1002/zaac.19905860114 . 99–105 . de.
  22. Hake . Dietmar . Urland . Werner . Darstellung und Kristallstruktur von LnAl3Br12 (Ln = La, Ce, Pr, Nd, Sm, Gd) und thermischer Abbau zu LnBr3 . Zeitschrift für anorganische und allgemeine Chemie . Wiley . 613 . 7 . 1992 . 0044-2313 . 10.1002/zaac.19926130107 . 45–48 . de.
  23. Urland . W. . Tietz . F. . Superconductivity in the Bi-Sr-Mg-Cu-O system . Materials Research Bulletin . Elsevier BV . 24 . 4 . 1989 . 0025-5408 . 10.1016/0025-5408(89)90032-9 . 489–492.
  24. Heinrich . A. . Urland . W. . The system Ba0.6K0.4−xCsxBiO3: Superconductivity dependence of Tc on the cesium content . Solid State Communications . Elsevier BV . 80 . 7 . 1991 . 0038-1098 . 10.1016/0038-1098(91)90064-3 . 519–522. 1991SSCom..80..519H .
  25. Köhler . Joachim . Urland . Werner . Ionic Conductivity in Na+/Pr3+–β"–Al2O3 Crystals . Journal of Solid State Chemistry . Elsevier BV . 127 . 2 . 1996 . 0022-4596 . 10.1006/jssc.1996.0372 . 161–168.
  26. J. Köhler and W. Urland Angew. Chem. 109, 150 (1997)
  27. Köhler . Joachim . Urland . Werner . On the Mobility of Trivalent Ions: Pr3+ in Pr3+-β"-Al2O3 . Angewandte Chemie International Edition in English . Wiley . 36 . 12 . 3 February 1997 . 0570-0833 . 10.1002/anie.199700851 . 85–87.
  28. Soetebier . Frank . Urland . Werner . Strukturchemische und magnetische Untersuchungen an Ho3+-β"-Al2O3(Ho0, 5Mg0, 5Al10, 5O17) . Zeitschrift für anorganische und allgemeine Chemie . Wiley . 628 . 3 . 2002 . 0044-2313 . 10.1002/1521-3749(200203)628:3<711::aid-zaac711>3.0.co;2-g . 711–714 . de.
  29. Soetebier . Frank . Urland . Werner . Structural Chemistry and Magnetism of Tb3+-β′′-Alumina (Tb0.46Al10.62Mg0.38O17) . European Journal of Inorganic Chemistry . Wiley . 2002 . 7 . 2002 . 1434-1948 . 10.1002/1099-0682(200207)2002:7<1673::aid-ejic1673>3.0.co;2-f . 1673–1676.
  30. Rüscher . C.H. . Heinrich . A. . Urland . W. . Bipolaron absorption in Ba1−xKxBiO3 and Ba0.6K0.4 − xCsxBiO3 . Physica C: Superconductivity . Elsevier BV . 219 . 3–4 . 1994 . 0921-4534 . 10.1016/0921-4534(94)90402-2 . 471–482. 1994PhyC..219..471R .
  31. Gerloch . M. . Kohl . J. . Lewis . J. . Urland . W. . Single-crystal polarized spectrum and paramagnetic anisotropy of five-co-ordinate, square pyramidal cobalt(II) complexes . Journal of the Chemical Society A: Inorganic, Physical, Theoretical . Royal Society of Chemistry (RSC) . 1970 . 0022-4944 . 10.1039/j19700003283 . 3269–3283.
  32. Urland . W. . On the ligand-field potential for f electrons in the angular overlap model . Chemical Physics . Elsevier BV . 14 . 3 . 1976 . 0301-0104 . 10.1016/0301-0104(76)80136-x . 393–401. 1976CP.....14..393U .
  33. Urland . W. . The interpretation of the crystal field parameters for fn-electron systems by the angular overlap model. The rare-earth hydroxides . Chemical Physics Letters . Elsevier BV . 50 . 3 . 1977 . 0009-2614 . 10.1016/0009-2614(77)80363-1 . 445–450. 1977CPL....50..445U .
  34. Urland . W. . The interpretation of the crystal field parameters for fn-electron systems by the angular overlap model. Rare-earth ions in LaCl3 . Chemical Physics Letters . Elsevier BV . 53 . 2 . 1978 . 0009-2614 . 10.1016/0009-2614(78)85400-1 . 296–299. 1978CPL....53..296U .
  35. B. N. Figgis, M. A. Hitchman, Ligand Field Theory and its Applications, Wiley-VCH, New York, 2000
  36. D. J. Newman, B. K. C. Ng, Crystal Field Handbook, Cambridge University Press, Cambridge, 2000
  37. B. G. Wybourne, Spectroscopic Properties of Rare Earths, Wiley Interscience, New York, 1965
  38. Stevens . K W H . Matrix Elements and Operator Equivalents Connected with the Magnetic Properties of Rare Earth Ions . Proceedings of the Physical Society. Section A . IOP Publishing . 65 . 3 . 1 March 1952 . 0370-1298 . 10.1088/0370-1298/65/3/308 . 209–215. 1952PPSA...65..209S . 98618693 .
  39. Schäffer . Claus E. . Jørgensen . Chr. Klixbüll . The angular overlap model, an attempt to revive the ligand field approaches . Molecular Physics . Informa UK Limited . 9 . 5 . 1965 . 0026-8976 . 10.1080/00268976500100551 . 401–412. 1965MolPh...9..401S .
  40. P. E. Hoggard, Struct. Bonding. 2004, 106, 37-57
  41. T. Schönherr, M. Atanasov, H. Adamsky, Angular Overlap Model, in A. B. P. Lever, J. A. McCleverty, T. J. Meyer (Eds.) Comprehensive coordination chemistry II, Vol. 2. Elsevier, Oxford, 2003, pp. 443-455.
  42. Urland . Werner . Hallfeldt . Jens . Synthese und Kristallstrukturen von (2-Methylpyridinium)3[TbCl<sub>6</sub>] und (2-Methylpyridinium)2[TbCl<sub>5</sub>(1-Butanol)] . Zeitschrift für anorganische und allgemeine Chemie . Wiley . 626 . 12 . 2000 . 0044-2313 . 10.1002/1521-3749(200012)626:12<2569::aid-zaac2569>3.0.co;2-0 . 2569–2573 . de.
  43. Hallfeldt . Jens . Urland . Werner . Synthese und Kristallstrukturen von (3-Methylpyridinium)3[DyCl<sub>6</sub>] und (3-Methylpyridinium)2[DyCl<sub>5</sub>(Ethanol)] . Zeitschrift für anorganische und allgemeine Chemie . Wiley . 627 . 3 . 2001 . 0044-2313 . 10.1002/1521-3749(200103)627:3<545::aid-zaac545>3.0.co;2-z . 545–548. free .
  44. Hallfeldt . Jens . Urland . Werner . Synthese, Kristallstruktur und magnetisches Verhalten von (2,4,6-Trimethylpyridinium)10[ErCl<sub>6</sub>][ErCl<sub>5</sub>(H<sub>2</sub>O)]2Cl3 . Zeitschrift für anorganische und allgemeine Chemie . Wiley . 628 . 12 . 2002 . 0044-2313 . 10.1002/1521-3749(200212)628:12<2661::aid-zaac2661>3.0.co;2-u . 2661–2664 . de.
  45. Urland . W. . Preparation, crystal structure and magnetic properties of complex rare earth nitrates . Journal of the Less Common Metals . Elsevier BV . 93 . 2 . 1983 . 0022-5088 . 10.1016/0022-5088(83)90199-6 . 431–432.
  46. Urland . W. . Kremer . R. . Electron spin resonance spectra of low-symmetry rare-earth complexes: tetraphenylarsonium pentakis(nitrato)ytterbate(III) . Inorganic Chemistry . American Chemical Society (ACS) . 23 . 11 . 1984 . 0020-1669 . 10.1021/ic00179a017 . 1550–1553.
  47. Urland . W. . Kremer . R. . Furrer . A. . Crystal field levels in tetraphenylarsoniumpentakis(nitrato)ytterbate(III) determined by neutron spectroscopy . Chemical Physics Letters . Elsevier BV . 132 . 2 . 1986 . 0009-2614 . 10.1016/0009-2614(86)80090-2 . 113–115. 1986CPL...132..113U .
  48. Urland . W. . Hochheimer . H.D. . Kourouklis . G.A. . Kremer . R. . The first observation of a crossing of crystal-field levels . Journal of the Less Common Metals . Elsevier BV . 111 . 1–2 . 1985 . 0022-5088 . 10.1016/0022-5088(85)90190-0 . 221.
  49. Urland . W. . Hochheimer . H.D. . Kourouklis . G.A. . Kremer . R. . Pressure-dependent crystal field splitting of Pr3+ in LaCl3: The observation of a crossing of crystal field levels . Solid State Communications . Elsevier BV . 55 . 7 . 1985 . 0038-1098 . 10.1016/0038-1098(85)90831-2 . 649–651. 1985SSCom..55..649U .
  50. Urland . W. . Hochheimer . H.D. . Kourouklis . G.A. . Kremer . R. . The first observation of a crossing of crystal field levels . Physica B+C . Elsevier BV . 139-140 . 1986 . 0378-4363 . 10.1016/0378-4363(86)90647-9 . 553–554. 1986PhyBC.139..553U .
  51. Urland . Werner . Magnetische Eigenschaften der Normaltemperaturform von CsTmO2 / Magnetic Properties of the Normal-Temperature Form of CsTmO2 . Zeitschrift für Naturforschung A . Walter de Gruyter GmbH . 34 . 8 . 1 August 1979 . 1865-7109 . 10.1515/zna-1979-0813 . 997–1002. 1979ZNatA..34..997U . 96245048 . free .
  52. Urland . Werner . Magnetische Eigenschaften der Normaltemperaturform von CsYbO2 . Zeitschrift für Naturforschung A . Walter de Gruyter GmbH . 35 . 2 . 1 January 1980 . 1865-7109 . 10.1515/zna-1980-0213 . 247–251. 96531405 . free .
  53. Urland . W. . Magnetische Eigenschaften der Thuliumverbindungen Cs2MTmF6 (M = Na, K, Rb) und Cs2KTmX6 (X = Cl, Br) . Berichte der Bunsengesellschaft für physikalische Chemie . Wiley . 83 . 10 . 1979 . 0005-9021 . 10.1002/bbpc.19790831017 . 1042–1046.
  54. Urland . Werner . Über des magnetische Verhalten von Cs2MYbF6 (M = Na, K, Rb) und Cs2NaYbBr6 . On the Magnetic Behaviour of Cs2MYbF6 (M = Na, K, Rb) and Cs2NaYbBr6 . Zeitschrift für Naturforschung A . Walter de Gruyter GmbH . 34 . 12 . 1 January 1979 . 1865-7109 . 10.1515/zna-1979-1218 . 1507–1511. 93923011 . free .
  55. Urland . W. . Feldner . K. . Hoppe . R. . Über das Magnetische Verhalten von Cs2KPrF6 und Cs2RbPrF6 . Zeitschrift für anorganische und allgemeine Chemie . Wiley . 465 . 1 . 1980 . 0044-2313 . 10.1002/zaac.19804650102 . 7–14 . de.
  56. Hatscher . Stephan T. . Urland . Werner . Unexpected Appearance of Molecular Ferromagnetism in the Ordinary Acetate [2]⋅4 H2O . Angewandte Chemie International Edition . Wiley . 42 . 25 . 30 June 2003 . 1433-7851 . 10.1002/anie.200250738 . 2862–2864. 12833342 .
  57. Rohde . Alexander . Urland . Werner . Synthese und Kristallstrukturen von Ln(ClF2CCOO)3(H2O)3 (Ln = Gd, Dy, Ho, Er) und magnetisches Verhalten von Gd(ClF2CCOO)3(H2O)3 . Zeitschrift für anorganische und allgemeine Chemie . Wiley . 630 . 13–14 . 2004 . 0044-2313 . 10.1002/zaac.200400173 . 2434–2437 . de.
  58. Rohde . Alexander . Urland . Werner . Synthese, Kristallstruktur und magnetisches Verhalten von [NH<sub>3</sub>CH<sub>3</sub>][Gd(Cl<sub>2</sub>HCCOO)<sub>4</sub>] . Zeitschrift für anorganische und allgemeine Chemie . Wiley . 631 . 2–3 . 2005 . 0044-2313 . 10.1002/zaac.200400290 . 417–420 . de.
  59. M. Atanansov, C. A. Daul and C. Rauzy, Struct. Bond., 2004, 106, 97
  60. Ramanantoanina . Harry . Urland . Werner . Cimpoesu . Fanica . Daul . Claude . Ligand field density functional theory calculation of the 4f2 → 4f15d1 transitions in the quantum cutter Cs2KYF6:Pr3+ . Physical Chemistry Chemical Physics . Royal Society of Chemistry (RSC) . 15 . 33 . 2013 . 13902–10 . 1463-9076 . 10.1039/c3cp51344k . 23846586 . 2013PCCP...1513902R .
  61. Ramanantoanina . Harry . Urland . Werner . García-Fuente . Amador . Cimpoesu . Fanica . Daul . Claude . Calculation of the 4f1→4f05d1 transitions in Ce3+-doped systems by Ligand Field Density Functional Theory . Chemical Physics Letters . Elsevier BV . 588 . 2013 . 0009-2614 . 10.1016/j.cplett.2013.10.012 . 260–266. 2013CPL...588..260R .
  62. Ramanantoanina . Harry . Urland . Werner . García-Fuente . Amador . Cimpoesu . Fanica . Daul . Claude . Ligand field density functional theory for the prediction of future domestic lighting . Phys. Chem. Chem. Phys. . Royal Society of Chemistry (RSC) . 16 . 28 . 2014 . 1463-9076 . 10.1039/c3cp55521f . 14625–14634. 24855637 . 2014PCCP...1614625R . 24140789 .
  63. Ramanantoanina . Harry . Urland . Werner . Cimpoesu . Fanica . Daul . Claude . The angular overlap model extended for two-open-shell f and d electrons . Phys. Chem. Chem. Phys. . Royal Society of Chemistry (RSC) . 16 . 24 . 2014 . 1463-9076 . 10.1039/c4cp01193g . 12282–12290. 24819302 . 2014PCCP...1612282R .
  64. Ramanantoanina . Harry . Urland . Werner . Herden . Benjamin . Cimpoesu . Fanica . Daul . Claude . Tailoring the optical properties of lanthanide phosphors: prediction and characterization of the luminescence of Pr3+-doped LiYF4 . Physical Chemistry Chemical Physics . Royal Society of Chemistry (RSC) . 17 . 14 . 2015 . 1463-9076 . 10.1039/c4cp05148c . 9116–9125. 25759864 . 2015PCCP...17.9116R . free .
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  67. Neuhausen . Christine . Hatscher . Stephan T. . Panthöfer . Martin . Urland . Werner . Tremel . Wolfgang . Comprehensive Uranium Thiophosphate Chemistry: Framework Compounds Based on Pseudotetrahedrally Coordinated Central Metal Atoms . Zeitschrift für anorganische und allgemeine Chemie . Wiley . 639 . 15 . 23 September 2013 . 0044-2313 . 10.1002/zaac.201300300 . 2836–2845.
  68. Morrison . Gregory . Ramanantoanina . Harry . Urland . Werner . Smith . Mark D. . zur Loye . Hans-Conrad . Flux Synthesis, Structure, Properties, and Theoretical Magnetic Study of Uranium(IV)-Containing A2USi6O15(A = K, Rb) with an Intriguing Green-to-Purple, Crystal-to-Crystal Structural Transition in the K Analogue . Inorganic Chemistry . American Chemical Society (ACS) . 54 . 11 . 15 May 2015 . 0020-1669 . 10.1021/acs.inorgchem.5b00556 . 5504–5511. 25978501 . 197379214 .

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