Svilen Bobev

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Svilen Bobev

Assistant Professor, Solid State and Inorganic Chemistry
(302) 831-8720
sbobev@udel.edu
http://www.udel.edu/chem/bobev/


(b. 1972) B.S./M.S., 1995, University of Sofia; Ph.D., 2002, University of Notre Dame; Postdoctoral, 2002 – 2004, Los Alamos National Laboratory

CURRENT RESEARCH
The research in our solid-state chemistry group focuses on the synthesis and structural characterization of new materials that exhibit intriguing chemical and physical properties. We are particularly interested in better understanding the structure-property relationships in several general types of intermetallic compounds, i.e. chemical species containing only metal atoms in specific crystalline arrangements. In these seemingly simple systems, the similar electronegativities, atomic sizes, coordination numbers and chemical potentials of the constituent metals lead to quite complicated phase diagrams. As a result of that, many phases may “contend” for existence at given experimental conditions, which makes predicting a new material or designing its synthesis more or less unfeasible. Therefore, systematic syntheses coupled with precise structure determination and accurate properties measurements are very important to identify structural patterns and understand their relation to the materials’ properties. This ability to recognize relationships between well studied systems and systems yet to be explored is of utmost importance since it may provide some logical and reasonable predictions for possible compounds, their likely structures or main structural features, and to certain degree – about their potential properties.



METHODS AND TECHNIQUES: A variety of classic high temperature solid-state techniques are typically used to prepare the desired materials in crystalline form (single crystals or polycrystalline samples). The crystal structures of the synthesized compounds are then determined using single-crystal or powder X-ray diffraction. The products are further characterized by elemental analysis, calorimetry, magnetic susceptibility and electrical resistivity measurements.

In order to obtain accurate measurements on most tensor properties or to eliminate the effects caused by grain boundaries in polycrystalline samples, the availability of sizeable single crystals is very important. Therefore, to a very large extent, our synthetic efforts are tied with techniques for crystal growth. Whereas there are severalgeneral methods developed for the growth of single crystals of inter-metallic compounds, one ofthem, growth out of metal fluxes is particularly not require specialized equipment, allows for low growth temperatures, and permits for an extremely simple removal of the crystals from the solution. Approp-riate choice of flux metal and temperature choice of flux metal and temperature conditions often results in the growth of large single crystals.



RECENT PUBLICATIONS
P. H. Tobash, J. J. Meyers, G. DiFilippo, S. Bobev, F. Ronning, J. D. Thompson and J. L. Sarrao “Structure and Properties of a New Family of Nearly Equiatomic Rare-earth Metal-Tin-Germanides RESn1+xGe1–x (RE = Y, Gd–Tm): an Unusual Example for Site Preferences Between Elements from the Same Group,” Chem. Mater., (2008) 20, 2151 - available on-line 02/25/2008.

S.-Q. Xia and S. Bobev, “Zintl Phase Variations Through Cation Selection. Synthesis and Structure of A21Cd4Pn18 (A =Eu, Sr, Ba; Pn = Sb, Bi),” Inorg. Chem., (2008) 47, 1919 - available on-line 02/21/2008.

S.-Q. Xia and S. Bobev “Synthesis, Structural Characterization, Electronic Structure and Magnetic Properties of the New Zintl Phase Eu10Cd6Bi12 ,” Chem. Asian J., (2007) 2, 619.

P. H. Tobash and S. Bobev “Synthesis, Structure and Electronic Structure of a New Polymorph of CaGe2 ,”
J. Solid State Chem., (2007) 180, 1575.

S.-Q. Xia and S. Bobev “Cation-anion Interactions as Structure Directing Factors: Structure and Bonding of Ca2CdSb2 and Yb2CdSb2 ,” J. Am. Chem. Soc., (2007) 129, 4049.

S.-Q. Xia and S. Bobev “Diverse Polyanions Based on MnBi4 and MnSb4 Tetrahedra: Polymorphism, Structure and Bonding in Ca21Mn4Bi18 and Ca21Mn4Sb18 ,” Inorg. Chem., (2007) 46, 874.

P. H. Tobash and S. Bobev “Structure and Bonding in Yb4MgGe4: Yb2+/Yb3+ Mixed Valency and Charge Ordering,” J. Am. Chem. Soc., (2006) 128, 3252.

S.-Q. Xia and S. Bobev “Ba11Cd8Bi14: Bismuth Zigzag Chains in a Ternary Alkaline-Earth Transition Metal Zintl Phase,” Inorg. Chem., (2006) 45, 7126.