Monday, March 29, 2010

Acronym in materials science: LAMOX for lanthanum molybdenum oxide

In chemistry and materials science, the term LAMOX stands for lanthanum molybdenum oxide. In particular, the name LAMOX refers to a material with compositional formula La2Mo2O9.

LAMOX is a fast oxygen ion (O2-) conductor. It undergoes a structural phase transition from the nonconductive monoclinic form to the highly conductive cubic form at a temperature of about 580 °C.

In fact, LAMOX is the parent of a whole family of oxides, whose members are derived by substituting some of the lanthanum atoms by strontium, barium, potassium, or bismuth atoms and/or some of the molybdenum atoms by rhenium, sulfur, tungsten, chromium, vanadium, niobium, or tantalum atoms. In some of those modified LAMOX compounds the phase transition is suppressed and the anion-conducting phase is stabilized, even at room temperature.

Keywords: oxide-ion conductor, solid solutions, conductivity of anions, crystal structure, local disorder, variable compound composition

Selected references
[1] F. Goutenoire, O. Isnard, E. Surad, O. Bohnke, Y. laligant, R. Retoux and Ph. Lacorre: Structural and transport characteristics of the LAMOX family of fast oxide-ion conductors, based on lanthanum molybdenum oxide La2Mo2O9. J. Mater. Chem. 2001, 11, pp. 119-124. DOI: 10.1039/b002962i.
[2] S. Georges, F. Goutenoire, O. Bohnke, M. C. Steil, S. J. Skinner, H.-D. Wiemhöfer and P. Lacorre: The LAMOX Family of Fast Oxide-Ion Conductors: Overview and Recent Results. Journal of New Materials for Electrochemical Systems 2004, 7, pp. 51-57. PDF version.
[3] L. Malavasi, H.-J. Kim, S. J. L. Billinge, T. Proffen, C. Tealdi and G. Flor: Nature of the Monoclinic to Cubic Phase Transition in the Fast Oxygen Ion Conductor La2Mo2O9 (LAMOX). J. Am. Chem. Soc. 2007, 129, pp. 6903-6907. DOI: 10.1021/ja071281e.
[4] Z.S. Khadasheva, N. U. Venskovskii, M. G. Safronenko, A.V. Mosunov, E.D. Politova and S. Y. Stefanovich: Synthesis and Properties of La2(Mo1-xMx)2O9 (M = Nb, Ta) Ionic Conductors. Inorg. Mat. November 2002, 38 (11), pp. 1168-1171.

Tuesday, March 23, 2010

Fresno, the Spanish word for ash tree on maps of Upper California (Alta California)

Fresno is the Spanish word for ash tree. This word is found in geographical names identifying locations in Upper California (Alta California): Fresno River, Fresno County and the city of Fresno.

The Fresno River, whose water originates in the Sierra Nevada Range, is a major tributary to the San Joaquin River of the southern part of California's Central Valley. Fresno is the largest city of the San Joaquin Valley and currently the fifth largest city of California. Fresno is the seat of Fresno County. The county is said to be named after Fresno Creek, found in Spanish-language-annotated maps from the days when Upper California was “explored” by Spanish-speaking missionaries from Mexico.

Fresno is typically associated with the ash tree species Fraxinus velutina, which occurs in the southwest region of the United States and northern Mexico. Its common name is Velvet Ash, but the terms Modesto Ash, Arizona Ash or Desert Ash are also used. The range of the velvet ash overlaps with that of the Berlandier Ash (Fraxinus berlandierana), also called Mexican ash. The range of the Oregon ash (Fraxinus latifolia) also includes parts of California, but, as the name indicates, this species is more common in moist habitats along the coast of Oregon and Washington.

Ashes are of genus Fraxinus belonging to the olive family (Oleaceae). Ash species grow in various countries of the Americas and on other continents, where they also play a role in composing geographical names. In Germany, for example, the town names Eschenbach, Eschwege, and Eschweiler hint to the presence of ash trees (Eschen or Eschenbäume in German) during the making and naming of these German fresno settlements.

[1] The Smithsonian Guide to Historic AmericaThe Pacific States. Stewart, Tabori & Chang, New York, 1989; pp. 162-163.
[2] Fresno County History at
[3] D. A. Sibley: The Sibley Guide To Trees. Alfred A. Knopf, New York, 2009; pp. 375-388 (Olive Family).

Saturday, March 6, 2010

Acronym in chemistry: ROY for red, orange and yellow, designating a polymorph-model compound

The organic compound with the common name ROY is 5-methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile (C12H9N3O2S, see molecular structure above). The acronym ROY obviously does not abbreviate this structural name, but stands for the color adjectives red, orange and yellow associated with its multiple crystal forms or polymorphs [1]. Nine polymorphic systems are known for ROY, obtained by different crystallization/transformation procedures including crystallization from solution, melt and vapor phase.

[1] Joel Bernstein: Cultivating crystal forms. Chem. Comm. 2005, pp. 5007-5012. DOI: 10.1039/b509670g.