Werner Urland

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Werner Urland
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Werner Urland
Born(1944-04-13)13 April 1944
Website www.life-and-science-institute.com

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]

Contents

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 [Si2 O 7] (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 [LnCl6]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 [LnCl6]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(NO3)5]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.

Related Research Articles

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Indium(III) bromide, (indium tribromide), InBr3, is a chemical compound of indium and bromine. It is a Lewis acid and has been used in organic synthesis.

There are three sets of Indium halides, the trihalides, the monohalides, and several intermediate halides. In the monohalides the oxidation state of indium is +1 and their proper names are indium(I) fluoride, indium(I) chloride, indium(I) bromide and indium(I) iodide.

The nitridoborates are chemical compounds of boron and nitrogen with metals. These compounds are typically produced at high temperature by reacting hexagonal boron nitride with metal nitrides or by metathesis reactions involving nitridoborates. A wide range of these compounds have been made involving lithium, alkaline earth metals and lanthanides, and their structures determined using crystallographic techniques such as X-ray crystallography. Structurally one of their interesting features is the presence of polyatomic anions of boron and nitrogen where the geometry and the B–N bond length have been interpreted in terms of π-bonding.

The inorganic imides are compounds containing an ion composed of nitrogen bonded to hydrogen with formula HN2−. Organic imides have the NH group, and two single or one double covalent bond to other atoms. The imides are related to the inorganic amides (H2N−), the nitrides (N3−) and the nitridohydrides (N3−•H−).

The telluride iodides are chemical compounds that contain both telluride ions (Te2−) and iodide ions (I−). They are in the class of mixed anion compounds or chalcogenide halides.

Nitride fluorides containing nitride and fluoride ions with the formula NF4-. They can be electronically equivalent to a pair of oxide ions O24-. Nitride fluorides were discovered in 1996 by Lavalle et al. They heated diammonium technetium hexafluoride to 300 °C to yield TcNF. Another preparation is to heat a fluoride compound with a nitride compound in a solid state reaction. The fluorimido ion is F-N2- and is found in a rhenium compound.

Sulfidostannates, or thiostannates are chemical compounds containing anions composed of tin linked with sulfur. They can be considered as stannates with sulfur substituting for oxygen. Related compounds include the thiosilicates, and thiogermanates, and by varying the chalcogen: selenostannates, and tellurostannates. Oxothiostannates have oxygen in addition to sulfur. Thiostannates can be classed as chalcogenidometalates, thiometallates, chalcogenidotetrelates, thiotetrelates, and chalcogenidostannates. Tin is almost always in the +4 oxidation state in thiostannates, although a couple of mixed sulfides in the +2 state are known,

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Caesium ozonide (CsO3) is an oxygen-rich compound of caesium. It is an ozonide, meaning it contains the ozonide anion (O3−). It can be formed by reacting ozone with caesium superoxide:

<span class="mw-page-title-main">Rubidium ozonide</span> Chemical compound

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<span class="mw-page-title-main">Lanthanum phosphide</span> Chemical compound

Lanthanum phosphide is an inorganic compound of lanthanum and phosphorus with the chemical formula LaP.

Arsenide bromides or bromide arsenides are compounds containing anions composed of bromide (Br−) and arsenide (As3−). They can be considered as mixed anion compounds. They are in the category of pnictidehalides. Related compounds include the arsenide chlorides, arsenide iodides, phosphide bromides, and antimonide bromides.

An iodide nitride is a mixed anion compound containing both iodide (I−) and nitride ions (N3−). Another name is metalloiodonitrides. They are a subclass of halide nitrides or pnictide halides. Some different kinds include ionic alkali or alkaline earth salts, small clusters where metal atoms surround a nitrogen atom, layered group 4 element 2-dimensional structures, and transition metal nitrido complexes counter-balanced with iodide ions. There is also a family with rare earth elements and nitrogen and sulfur in a cluster.

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Carbide bromides are mixed anion compounds containing bromide and carbide anions. Many carbide bromides are cluster compounds, containing on, two or more carbon atoms in a core, surrounded by a layer of metal atoms, encased in a shell of bromide ions. These ions may be shared between clusters to form chains, double chains or layers.

Carbide iodides are mixed anion compounds containing iodide and carbide anions. Many carbide iodides are cluster compounds, containing one, two or more carbon atoms in a core, surrounded by a layer of metal atoms, and encased in a shell of iodide ions. These ions may be shared between clusters to form chains, double chains or layers.

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<span class="mw-page-title-main">Europium compounds</span> Compounds with at least one europium atom

Europium compounds are compounds formed by the lanthanide metal europium (Eu). In these compounds, europium generally exhibits the +3 oxidation state, such as EuCl3, Eu(NO3)3 and Eu(CH3COO)3. Compounds with europium in the +2 oxidation state are also known. The +2 ion of europium is the most stable divalent ion of lanthanide metals in aqueous solution. Many europium compounds fluoresce under ultraviolet light due to the excitation of electrons to higher energy levels. Lipophilic europium complexes often feature acetylacetonate-like ligands, e.g., Eufod.

<span class="mw-page-title-main">Gadolinium diiodide</span> Chemical compound

Gadolinium diiodide is an inorganic compound, with the chemical formula of GdI2. It is an electride, with the ionic formula of Gd3+(I−)2e−, and therefore not a true gadolinium(II) compound. It is ferromagnetic at 276 K with a saturation magnetization of 7.3 B; it exhibits a large negative magnetoresistance (~70%) at 7 T near room temperature. It can be obtained by reacting gadolinium and gadolinium(III) iodide at a high temperature:

<span class="mw-page-title-main">Seleninyl fluoride</span> Chemical compound

Seleninyl fluoride is an oxyfluoride of selenium with the chemical formula SeOF2.

References

  1. ↑ Schäffer, Claus E.; Jørgensen, Chr. Klixbüll (1965). "The angular overlap model, an attempt to revive the ligand field approaches". Molecular Physics. Informa UK Limited. 9 (5): 401–412. Bibcode:1965MolPh...9..401S. doi:10.1080/00268976500100551. ISSN   0026-8976.
  2. ↑ Hoggard, Patrick E. (2004). "Angular Overlap Model Parameters". Optical Spectra and Chemical Bonding in Inorganic Compounds. Structure and Bonding. Vol. 106. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 37–57. doi:10.1007/b11304. ISBN   978-3-540-00853-8. ISSN   0081-5993.
  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. (1976). "On the ligand-field potential for f electrons in the angular overlap model". Chemical Physics. Elsevier BV. 14 (3): 393–401. Bibcode:1976CP.....14..393U. doi:10.1016/0301-0104(76)80136-x. ISSN   0301-0104.
  5. ↑ Urland, W. (1977). "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): 457–460. Bibcode:1977CPL....46..457U. doi:10.1016/0009-2614(77)80627-1. ISSN   0009-2614.
  6. ↑ Urland, W. (1981). "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): 58–62. Bibcode:1981CPL....77...58U. doi:10.1016/0009-2614(81)85599-6. ISSN   0009-2614.
  7. ↑ Tang, Jinkui; Hewitt, Ian; Madhu, N. T.; Chastanet, Guillaume; Wernsdorfer, Wolfgang; Anson, Christopher E.; Benelli, Cristiano; Sessoli, Roberta; Powell, Annie K. (6 March 2006). "Dysprosium Triangles Showing Single-Molecule Magnet Behavior of Thermally Excited Spin States". Angewandte Chemie International Edition. Wiley. 45 (11): 1729–1733. doi:10.1002/anie.200503564. ISSN   1433-7851. PMID   16496432.
  8. ↑ Costes, Jean-Pierre; Dahan, Françoise; Wernsdorfer, Wolfgang (2006). "Heterodinuclear Cu−Tb Single-Molecule Magnet". Inorganic Chemistry. American Chemical Society (ACS). 45 (1): 5–7. doi:10.1021/ic050563h. ISSN   0020-1669. PMID   16390033.
  9. ↑ Cimpoesu, Fanica; Dahan, Françoise; Ladeira, Sonia; Ferbinteanu, Marilena; Costes, Jean-Pierre (21 March 2012). "Chiral Crystallization of a Heterodinuclear Ni-Ln Series: Comprehensive Analysis of the Magnetic Properties". Inorganic Chemistry. American Chemical Society (ACS). 51 (21): 11279–11293. doi:10.1021/ic3001784. ISSN   0020-1669. PMID   22435341.
  10. ↑ Jüstel, Thomas; Nikol, Hans; Ronda, Cees (4 December 1998). "New Developments in the Field of Luminescent Materials for Lighting and Displays". Angewandte Chemie International Edition. Wiley. 37 (22): 3084–3103. doi:10.1002/(sici)1521-3773(19981204)37:22<3084::aid-anie3084>3.0.co;2-w. ISSN   1433-7851. PMID   29711319.
  11. ↑ Plambeck-Fischer, P.; Urland, W.; Abriel, W. (1987). "Synthesis of PrSe2 and studies of single-crystal structure". Zeitschrift für Kristallographie. 178: 182.
  12. ↑ Plambeck-Fischer, P.; Urland, W.; Abriel, W. (1988). "Crystal-structure of CeSe1.9−x and PreSe1.9−x". Zeitschrift für Kristallographie. 182: 208.
  13. ↑ Plambeck-Fischer, P.; Abriel, W.; Urland, W. (1989). "Preparation and crystal structure of RESe1.9 (RE=Ce, Pr)". Journal of Solid State Chemistry. Elsevier BV. 78 (1): 164–169. Bibcode:1989JSSCh..78..164P. doi:10.1016/0022-4596(89)90140-0. ISSN   0022-4596.
  14. ↑ Urland, W.; Plambeck-Fischer, P.; Grupe, M. (1 March 1989). "Darstellung und Kristallstruktur von NdSe1.9" [Preparation and Crystal Structure of NdSe1.9]. Zeitschrift für Naturforschung B (in German). Walter de Gruyter GmbH. 44 (3): 261–264. doi: 10.1515/znb-1989-0303 . ISSN   1865-7117. S2CID   98369397.
  15. ↑ Grupe, M.; Urland, W. (1 April 1990). "Darstellung und Kristallstruktur von Nd2SeSiO4" [Preparation and Crystal Structure of Nd2SeSiO4]. Zeitschrift für Naturforschung B (in German). Walter de Gruyter GmbH. 45 (4): 465–468. doi: 10.1515/znb-1990-0410 . ISSN   1865-7117. S2CID   97491520.
  16. ↑ Grupe, Matthias; Lissner, Falk; Schleid, Thomas; Urland, Werner (1992). "Chalkogenid-Disilicate der Lanthanoide vom Typ M4X3[Si2O7] (M = Ce-Er; X = S, Se)". Zeitschrift für anorganische und allgemeine Chemie (in German). Wiley. 616 (10): 53–60. doi:10.1002/zaac.19926161009. ISSN   0044-2313.
  17. ↑ Grundmeier, Thorsten; Urland, Werner (1997). "Zur Kristallstruktur von Tb2Se3". Zeitschrift für anorganische und allgemeine Chemie (in German). Wiley. 623 (11): 1744–1746. doi: 10.1002/zaac.19976231113 . ISSN   0044-2313.
  18. ↑ Urland, Werner; Person, Helmut (1 August 1998). "Zur Kristallstruktur von Ho2Se3" [On the Crystal Structure of Ho2Se3]. Zeitschrift für Naturforschung B. Walter de Gruyter GmbH. 53 (8): 900–902. doi:10.1515/znb-1998-0821. ISSN   1865-7117. S2CID   100943831.
  19. ↑ Grundmeier, Thorsten; Urland, Werner (1995). "Zur Polymorphie von Sm2Se3". Zeitschrift für anorganische und allgemeine Chemie (in German). Wiley. 621 (11): 1977–1979. doi:10.1002/zaac.19956211125. ISSN   0044-2313.
  20. ↑ Grundmeier, T.; Heinze, Th.; Urland, W. (1997). "On the electronic structure of new ternary selenides of samarium". Journal of Alloys and Compounds. Elsevier BV. 246 (1–2): 18–20. doi:10.1016/s0925-8388(96)02466-8. ISSN   0925-8388.
  21. ↑ Hake, D.; Urland, W. (1990). "Darstellung und Kristallstruktur von LnAl3Cl12 (Ln = Tb, Dy, Ho) und thermischer Abbau zu LnCl3". Zeitschrift für anorganische und allgemeine Chemie (in German). Wiley. 586 (1): 99–105. doi:10.1002/zaac.19905860114. ISSN   0044-2313.
  22. ↑ Hake, Dietmar; Urland, Werner (1992). "Darstellung und Kristallstruktur von LnAl3Br12 (Ln = La, Ce, Pr, Nd, Sm, Gd) und thermischer Abbau zu LnBr3". Zeitschrift für anorganische und allgemeine Chemie (in German). Wiley. 613 (7): 45–48. doi:10.1002/zaac.19926130107. ISSN   0044-2313.
  23. ↑ Urland, W.; Tietz, F. (1989). "Superconductivity in the Bi-Sr-Mg-Cu-O system". Materials Research Bulletin. Elsevier BV. 24 (4): 489–492. doi:10.1016/0025-5408(89)90032-9. ISSN   0025-5408.
  24. ↑ Heinrich, A.; Urland, W. (1991). "The system Ba0.6K0.4−xCsxBiO3: Superconductivity dependence of Tc on the cesium content". Solid State Communications. Elsevier BV. 80 (7): 519–522. Bibcode:1991SSCom..80..519H. doi:10.1016/0038-1098(91)90064-3. ISSN   0038-1098.
  25. ↑ Köhler, Joachim; Urland, Werner (1996). "Ionic Conductivity in Na+/Pr3+–β"–Al2O3 Crystals". Journal of Solid State Chemistry. Elsevier BV. 127 (2): 161–168. doi:10.1006/jssc.1996.0372. ISSN   0022-4596.
  26. ↑ J. Köhler and W. Urland Angew. Chem. 109 , 150 (1997)
  27. ↑ Köhler, Joachim; Urland, Werner (3 February 1997). "On the Mobility of Trivalent Ions: Pr3+ in Pr3+-β"-Al2O3". Angewandte Chemie International Edition in English. Wiley. 36 (12): 85–87. doi:10.1002/anie.199700851. ISSN   0570-0833.
  28. ↑ Soetebier, Frank; Urland, Werner (2002). "Strukturchemische und magnetische Untersuchungen an Ho3+-β"-Al2O3(Ho0, 5Mg0, 5Al10, 5O17)". Zeitschrift für anorganische und allgemeine Chemie (in German). Wiley. 628 (3): 711–714. doi:10.1002/1521-3749(200203)628:3<711::aid-zaac711>3.0.co;2-g. ISSN   0044-2313.
  29. ↑ Soetebier, Frank; Urland, Werner (2002). "Structural Chemistry and Magnetism of Tb3+-β′′-Alumina (Tb0.46Al10.62Mg0.38O17)". European Journal of Inorganic Chemistry. Wiley. 2002 (7): 1673–1676. doi:10.1002/1099-0682(200207)2002:7<1673::aid-ejic1673>3.0.co;2-f. ISSN   1434-1948.
  30. ↑ Rüscher, C.H.; Heinrich, A.; Urland, W. (1994). "Bipolaron absorption in Ba1−xKxBiO3 and Ba0.6K0.4 − xCsxBiO3". Physica C: Superconductivity. Elsevier BV. 219 (3–4): 471–482. Bibcode:1994PhyC..219..471R. doi:10.1016/0921-4534(94)90402-2. ISSN   0921-4534.
  31. ↑ Gerloch, M.; Kohl, J.; Lewis, J.; Urland, W. (1970). "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): 3269–3283. doi:10.1039/j19700003283. ISSN   0022-4944.
  32. ↑ Urland, W. (1976). "On the ligand-field potential for f electrons in the angular overlap model". Chemical Physics. Elsevier BV. 14 (3): 393–401. Bibcode:1976CP.....14..393U. doi:10.1016/0301-0104(76)80136-x. ISSN   0301-0104.
  33. ↑ Urland, W. (1977). "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): 445–450. Bibcode:1977CPL....50..445U. doi:10.1016/0009-2614(77)80363-1. ISSN   0009-2614.
  34. ↑ Urland, W. (1978). "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): 296–299. Bibcode:1978CPL....53..296U. doi:10.1016/0009-2614(78)85400-1. ISSN   0009-2614.
  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 (1 March 1952). "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): 209–215. Bibcode:1952PPSA...65..209S. doi:10.1088/0370-1298/65/3/308. ISSN   0370-1298. S2CID   98618693.
  39. ↑ Schäffer, Claus E.; Jørgensen, Chr. Klixbüll (1965). "The angular overlap model, an attempt to revive the ligand field approaches". Molecular Physics. Informa UK Limited. 9 (5): 401–412. Bibcode:1965MolPh...9..401S. doi:10.1080/00268976500100551. ISSN   0026-8976.
  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 (2000). "Synthese und Kristallstrukturen von (2-Methylpyridinium)3[TbCl6] und (2-Methylpyridinium)2[TbCl5(1-Butanol)]". Zeitschrift für anorganische und allgemeine Chemie (in German). Wiley. 626 (12): 2569–2573. doi:10.1002/1521-3749(200012)626:12<2569::aid-zaac2569>3.0.co;2-0. ISSN   0044-2313.
  43. ↑ Hallfeldt, Jens; Urland, Werner (2001). "Synthese und Kristallstrukturen von (3-Methylpyridinium)3[DyCl6] und (3-Methylpyridinium)2[DyCl5(Ethanol)]". Zeitschrift für anorganische und allgemeine Chemie. Wiley. 627 (3): 545–548. doi: 10.1002/1521-3749(200103)627:3<545::aid-zaac545>3.0.co;2-z . ISSN   0044-2313.
  44. ↑ Hallfeldt, Jens; Urland, Werner (2002). "Synthese, Kristallstruktur und magnetisches Verhalten von (2,4,6-Trimethylpyridinium)10[ErCl6][ErCl5(H2O)]2Cl3". Zeitschrift für anorganische und allgemeine Chemie (in German). Wiley. 628 (12): 2661–2664. doi:10.1002/1521-3749(200212)628:12<2661::aid-zaac2661>3.0.co;2-u. ISSN   0044-2313.
  45. ↑ Urland, W. (1983). "Preparation, crystal structure and magnetic properties of complex rare earth nitrates". Journal of the Less Common Metals. Elsevier BV. 93 (2): 431–432. doi:10.1016/0022-5088(83)90199-6. ISSN   0022-5088.
  46. ↑ Urland, W.; Kremer, R. (1984). "Electron spin resonance spectra of low-symmetry rare-earth complexes: tetraphenylarsonium pentakis(nitrato)ytterbate(III)". Inorganic Chemistry. American Chemical Society (ACS). 23 (11): 1550–1553. doi:10.1021/ic00179a017. ISSN   0020-1669.
  47. ↑ Urland, W.; Kremer, R.; Furrer, A. (1986). "Crystal field levels in tetraphenylarsoniumpentakis(nitrato)ytterbate(III) determined by neutron spectroscopy". Chemical Physics Letters. Elsevier BV. 132 (2): 113–115. Bibcode:1986CPL...132..113U. doi:10.1016/0009-2614(86)80090-2. ISSN   0009-2614.
  48. ↑ Urland, W.; Hochheimer, H.D.; Kourouklis, G.A.; Kremer, R. (1985). "The first observation of a crossing of crystal-field levels". Journal of the Less Common Metals. Elsevier BV. 111 (1–2): 221. doi:10.1016/0022-5088(85)90190-0. ISSN   0022-5088.
  49. ↑ Urland, W.; Hochheimer, H.D.; Kourouklis, G.A.; Kremer, R. (1985). "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): 649–651. Bibcode:1985SSCom..55..649U. doi:10.1016/0038-1098(85)90831-2. ISSN   0038-1098.
  50. ↑ Urland, W.; Hochheimer, H.D.; Kourouklis, G.A.; Kremer, R. (1986). "The first observation of a crossing of crystal field levels". Physica B+C. Elsevier BV. 139–140: 553–554. Bibcode:1986PhyBC.139..553U. doi:10.1016/0378-4363(86)90647-9. ISSN   0378-4363.
  51. ↑ Urland, Werner (1 August 1979). "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): 997–1002. Bibcode:1979ZNatA..34..997U. doi: 10.1515/zna-1979-0813 . ISSN   1865-7109. S2CID   96245048.
  52. ↑ Urland, Werner (1 January 1980). "Magnetische Eigenschaften der Normaltemperaturform von CsYbO2". Zeitschrift für Naturforschung A. Walter de Gruyter GmbH. 35 (2): 247–251. doi: 10.1515/zna-1980-0213 . ISSN   1865-7109. S2CID   96531405.
  53. ↑ Urland, W. (1979). "Magnetische Eigenschaften der Thuliumverbindungen Cs2MTmF6 (M = Na, K, Rb) und Cs2KTmX6 (X = Cl, Br)". Berichte der Bunsengesellschaft für physikalische Chemie. Wiley. 83 (10): 1042–1046. doi:10.1002/bbpc.19790831017. ISSN   0005-9021.
  54. ↑ Urland, Werner (1 January 1979). "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): 1507–1511. doi: 10.1515/zna-1979-1218 . ISSN   1865-7109. S2CID   93923011.
  55. ↑ Urland, W.; Feldner, K.; Hoppe, R. (1980). "Über das Magnetische Verhalten von Cs2KPrF6 und Cs2RbPrF6". Zeitschrift für anorganische und allgemeine Chemie (in German). Wiley. 465 (1): 7–14. doi:10.1002/zaac.19804650102. ISSN   0044-2313.
  56. ↑ Hatscher, Stephan T.; Urland, Werner (30 June 2003). "Unexpected Appearance of Molecular Ferromagnetism in the Ordinary Acetate [{Gd(OAc)3(H2O)2}2]⋅4 H2O". Angewandte Chemie International Edition. Wiley. 42 (25): 2862–2864. doi:10.1002/anie.200250738. ISSN   1433-7851. PMID   12833342.
  57. ↑ Rohde, Alexander; Urland, Werner (2004). "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 (in German). Wiley. 630 (13–14): 2434–2437. doi:10.1002/zaac.200400173. ISSN   0044-2313.
  58. ↑ Rohde, Alexander; Urland, Werner (2005). "Synthese, Kristallstruktur und magnetisches Verhalten von [NH3CH3][Gd(Cl2HCCOO)4]". Zeitschrift für anorganische und allgemeine Chemie (in German). Wiley. 631 (2–3): 417–420. doi:10.1002/zaac.200400290. ISSN   0044-2313.
  59. ↑ M. Atanansov, C. A. Daul and C. Rauzy, Struct. Bond., 2004, 106, 97
  60. ↑ Ramanantoanina, Harry; Urland, Werner; Cimpoesu, Fanica; Daul, Claude (2013). "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): 13902–10. Bibcode:2013PCCP...1513902R. doi:10.1039/c3cp51344k. ISSN   1463-9076. PMID   23846586.
  61. ↑ Ramanantoanina, Harry; Urland, Werner; García-Fuente, Amador; Cimpoesu, Fanica; Daul, Claude (2013). "Calculation of the 4f1→4f05d1 transitions in Ce3+-doped systems by Ligand Field Density Functional Theory". Chemical Physics Letters. Elsevier BV. 588: 260–266. Bibcode:2013CPL...588..260R. doi:10.1016/j.cplett.2013.10.012. ISSN   0009-2614.
  62. ↑ Ramanantoanina, Harry; Urland, Werner; García-Fuente, Amador; Cimpoesu, Fanica; Daul, Claude (2014). "Ligand field density functional theory for the prediction of future domestic lighting". Phys. Chem. Chem. Phys. Royal Society of Chemistry (RSC). 16 (28): 14625–14634. Bibcode:2014PCCP...1614625R. doi:10.1039/c3cp55521f. ISSN   1463-9076. PMID   24855637. S2CID   24140789.
  63. ↑ Ramanantoanina, Harry; Urland, Werner; Cimpoesu, Fanica; Daul, Claude (2014). "The angular overlap model extended for two-open-shell f and d electrons". Phys. Chem. Chem. Phys. Royal Society of Chemistry (RSC). 16 (24): 12282–12290. Bibcode:2014PCCP...1612282R. doi:10.1039/c4cp01193g. ISSN   1463-9076. PMID   24819302.
  64. ↑ Ramanantoanina, Harry; Urland, Werner; Herden, Benjamin; Cimpoesu, Fanica; Daul, Claude (2015). "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): 9116–9125. Bibcode:2015PCCP...17.9116R. doi: 10.1039/c4cp05148c . ISSN   1463-9076. PMID   25759864.
  65. ↑ M. Atanansov, C. A. Daul and C. Rauzy, Struct. Bond., 2004, 106, 97
  66. ↑ M. Ferbinteanu, F. Cimpoesu and S. Tanase, Struct. Bond., 2015, 163, 185-230.
  67. ↑ Neuhausen, Christine; Hatscher, Stephan T.; Panthöfer, Martin; Urland, Werner; Tremel, Wolfgang (23 September 2013). "Comprehensive Uranium Thiophosphate Chemistry: Framework Compounds Based on Pseudotetrahedrally Coordinated Central Metal Atoms". Zeitschrift für anorganische und allgemeine Chemie. Wiley. 639 (15): 2836–2845. doi:10.1002/zaac.201300300. ISSN   0044-2313.
  68. ↑ Morrison, Gregory; Ramanantoanina, Harry; Urland, Werner; Smith, Mark D.; zur Loye, Hans-Conrad (15 May 2015). "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): 5504–5511. doi:10.1021/acs.inorgchem.5b00556. ISSN   0020-1669. PMID   25978501. S2CID   197379214.
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