Synthesis, structure, and XPS characterization of the stoichiometric phaseSr2CuO2F

Ab initioperiodic approach to electronic structure and magnetic exchange inA2CuO2X2Moreira1, Dovesi2 2003Phys. Rev. B10010View full textAdd to dashboardCite

“…9,13,14,18 However, the discovery of the superconducting oxyhalides was made in the middle 1990's, since their synthesis needs special procedures ͑usually including high pressure͒ to permit the formation of metastable phases under ambient conditions and to control the dopant concentrations in an efficient way. 10,11,[15][16][17] These new high pressure/high temperature synthetic methods opened the way to sintetize other important cuprate superconductor systems such as the infinite layered compound (Sr,Ca)CuO 2 ͑Refs. 72-74͒ or the ladder compounds.…”

“…In the case of oxyfluorides, there are only few experimental studies, mainly addressed to structural and synthetic aspects. [15][16][17][18][19][20] However, the close similarity between the structures and the nature of the ions of this family of compounds is usually invoqued as an argument to suppose that the electronic structures and, hence, electronic and magnetic properties of the oxyfluoride systems are similar to those of the most studied oxychlorides.…”

“…The family of oxyhalide compounds with formula A 2 CuO 2 X 2 (AϭCa ,Sr and XϭF ,Cl) [8][9][10][11][12][13][14][15][16][17][18][19][20] belongs to this class of simple cuprates which have also a smooth variation in their structural and chemical properties. This family is an optimal candidate to a theoretical research because its constituent ions are chemically simple ͑not trivalent lanthanides͒, have different structures without apical oxygens and have quite different superconducting behavior.…”

“…21 However, the closely related compounds Sr 2 CuO 2 Cl 2 , Ca 2 CuO 2 F 2ϩ␦ seem not to be superconducting for the available doping concentrations. 8,17,18 Since experimental and theoretical investigations of their properties seem to indicate that there are no substantial differences between them or with respect to other superconducting cuprates, it is important to study the electronic structure of the full set of compounds in detail in order to carefully evidentiate similarities and differences, and this will be the object of the present paper.…”

Oxyfluoride Chemistry of Layered Perovskite Compounds

“…The superconducting temperature takes a maximum value of T C = 46 K at δ ~ 0.3. Interestingly, reduction of Sr 2 CuO 2 F 2+δ in a flowing H 2 /N 2 gas atmosphere yields an insulating T'-structure Sr 2 CuO 2 F 2 [36] anion, but the fluorine insertion manner and coordination environment around the metal center are different between these two compounds (see Figure 9). Fluoride anions in Sr 2 TiO 3 F 2 occupy both the apical sites and interstitial sites in alternate rock-salt layers.…”