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Zintl Phases (zintl + phase)
Selected AbstractsTraversing the Metal-Insulator Transition in a Zintl Phase: Rational Enhancement of Thermoelectric Efficiency in Yb14Mn1,xAlxSb11,ADVANCED FUNCTIONAL MATERIALS, Issue 18 2008Eric S. Toberer Abstract For high temperature thermoelectric applications, Yb14MnSb11 has a maximum thermoelectric figure of merit (zT) of ,1.0 at 1273,K. Such a high zT is found despite a carrier concentration that is higher than typical thermoelectric materials. Here, we reduce the carrier concentration with the discovery of a continuous transition between metallic Yb14MnSb11 and semiconducting Yb14AlSb11. Yb14Mn1-xAlxSb11 forms a solid solution where the free carrier concentration gradually changes as expected from the Zintl valence formalism. Throughout this transition the electronic properties are found to obey a rigid band model with a band gap of 0.5,eV and an effective mass of 3 me. As the carrier concentration decreases, an increase in the Seebeck coefficient is observed at the expense of an increased electrical resistivity. At the optimum carrier concentration, a maximum zT of 1.3 at 1223,K is obtained, which is more than twice that of the state-of-the-art Si0.8Ge0.2 flown by NASA. [source] ChemInform Abstract: K6Tl2Sb3, a Zintl Phase with a Novel Heteroatomic 1,[Tl4Sb612- ] Chain.CHEMINFORM, Issue 37 2001Lisheng Chi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Electronic Structure of the A8Tr11 (A: K, Rb, Cs; Tr: Ga, In, Tl) Zintl Phases: Possible Chemical Reasons Behind Their Activated versus Non-Activated ConductivityCHEMINFORM, Issue 50 2009Manuel Cobian Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Concerning the Different Roles of Cations in Metallic Zintl Phases: Ba7Ga4Sb9 as a Test CaseCHEMINFORM, Issue 46 2006Pere Alemany Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Importance of Cations in the Properties of Zintl Phases: The Electronic Structure of and Bonding in Metallic Na6TlSb4CHEMINFORM, Issue 42 2005Anja-V. Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis and Characterization of Transition-Metal Zintl Phases: Cs24Nb2In12As18 and Cs13Nb2In6As10 with Isolated Complex Anions.CHEMINFORM, Issue 9 2004Franck Gascoin Abstract For Abstract see ChemInform Abstract in Full Text. [source] Intermetallics as Zintl Phases: Yb2Ga4Ge6 and RE3Ga4Ge6 (RE=Yb, Eu): Structural Response of a [Ga4Ge6]4, Framework to Reduction by Two ElectronsCHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2004Marina A. Zhuravleva Abstract Two new intermetallic compounds, Yb2Ga4Ge6 and Yb3Ga4Ge6, were obtained from reactions in molten Ga. A third compound, Eu3Ga4Ge6, was produced by direct combination of the elements. The crystal structures of these compounds were studied by single-crystal X-ray diffraction. Yb2Ga4Ge6 crystallizes in an orthorhombic cell with a=4.1698(7), b=23.254(4), c=10.7299(18) Å in the polar space group Cmc21. The structure of RE3Ga4Ge6 is monoclinic, space group C2/m, with cell parameters a=23.941(6), b=4.1928(11), c=10.918(3) Å, ,=91.426(4)° for RE=Yb, and a=24.136(2), b=4.3118(4), c=11.017(1) Å, ,=91.683(2)° for RE=Eu. The refinement [I>2,,(I)] converged to the final residuals R1/wR2=0.0229/0.0589, 0.0411/0.1114, and 0.0342/0.0786 for Yb2Ga4Ge6, Yb3Ga4Ge6, and Eu3Ga4Ge6, respectively. The structures of these two families of compounds can be described by a Zintl concept of bonding, in which the three-dimensional [Ga4Ge6]n, framework serves as a host and electron sink for the electropositive RE atoms. The structural relation of RE3Ga4Ge6 to of Yb2Ga4Ge6 lies in a monoclinic distortion of the orthorhombic cell of Yb2Ga4Ge6 and reduction of the [Ga4Ge6] network by two electrons per formula unit. The results of theoretical calculations of the electronic structure, electrical transport data, and thermochemical and magnetic measurements are also reported. [source] Synthesis and Crystal Structure of Mercury-Substituted Type-I Clathrates A8Hg4Sn42 (A = K, Rb, Cs)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 4 2008Andreas Kaltzoglou Abstract The mercury-substituted type-I clathrates A8Hg4Sn42,with A = K, Rb or Cs, were obtained by fusion of the pure elements at high temperatures. The crystal structures of the compounds were refined from single-crystal X-ray diffraction data. They crystallize in the space group Pmn (No. 223), Z = 1 with a = 12.1255(4) Å for K8Hg4Sn42 (1), a = 12.1838(4) Å for Rb8Hg4Sn42 (2) and a = 12.2130(4) Å for Cs8Hg4Sn42 (3). The 3D framework of four-bonded atoms defines two types of polyhedral cages of different size that are fully occupied by the alkali-metal atoms. All three compounds are considered as formally charge-balanced Zintl phases without any homogeneity range. Differential thermal analysis (DTA) indicates that the stability of the clathrates significantly depends on the size of the encaged cations. The thermal stability of the title compounds and the binary phases A8Sn44 (A = K, Rb, Cs) is discussed. Temperature-dependent magnetic measurements for compound 3 show also the expected diamagnetic behaviour. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Barium antimonide oxide, Ba3Sb2OACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2001Michael Boss The antimonide oxide Ba3Sb2O consists of discrete [Sb2]4, and O2, anions, and crystallizes with a new structure type. The Sb,Sb distances are comparable to those known from electron-precise zintl phases and the tetrahedral coordination of the O2, anion is also observed in some other Ba-rich metallide oxides. [source] | ||||||||||