High-Pressure Behavior of Silver Fluorides up to 40 GPa.

A combined experimental-theoretical study of silver(I) and silver(II) fluorides under high pressure is reported. For AgI, the CsCl-type structure is stable to at least 39 GPa; the overtone of the IR-active mode is seen in the Raman spectrum. Its AgIIF2 sibling is a unique compound in many ways: it is more covalent than other known difluorides, crystallizes in a layered structure, and is enormously reactive. Using X-ray diffraction and guided by theoretical calculations (density functional theory), we have been able to elucidate crystal structures of high-pressure polymorphs of AgF2. The transition from ambient pressure to an unprecedented nanotubular structure takes place via an intermediate orthorhombic layered structure, which lacks an inversion center. The observed phase transitions are discussed within the broader framework of the fluorite → cotunnite → Ni2In series, which has been seen for other metal difluorides.

[1]  Z. Mazej,et al.  Metal fluoride nanotubes featuring square-planar building blocks in a high-pressure polymorph of AgF2. , 2017, Dalton transactions.

[2]  M. Derzsi,et al.  Persistence of Mixed and Non-intermediate Valence in the High-Pressure Structure of Silver(I,III) Oxide, AgO: A Combined Raman, X-ray Diffraction (XRD), and Density Functional Theory (DFT) Study. , 2017, Inorganic chemistry.

[3]  F. Rodríguez Unveiling the Local Structure of Cu2+ Ions from d-Orbital Splitting. Application to K2ZnF4:Cu2+ and KZnF3:Cu2. , 2017, Inorganic chemistry.

[4]  A. Romero,et al.  First-principles study of pressure-induced structural phase transitions in MnF2. , 2016, Physical chemistry chemical physics : PCCP.

[5]  M. Derzsi,et al.  Crystal, electronic, and magnetic structures of M2AgF4 (M = Na-Cs) phases as viewed from the DFT+U method. , 2016, Dalton transactions.

[6]  I. Tanaka,et al.  First principles phonon calculations in materials science , 2015, 1506.08498.

[7]  H. Niu,et al.  A novel phase of beryllium fluoride at high pressure. , 2015, Physical chemistry chemical physics : PCCP.

[8]  H. Öztürk,et al.  Structural phase transformations and new intermediate phases of MgF2 under high-pressures applied via conjugate-gradient method , 2014 .

[9]  V. Petříček,et al.  Crystallographic Computing System JANA2006: General features , 2014 .

[10]  Z. Mazej,et al.  Na2AgF4: 1D antiferromagnet with unusually short Ag2+···Ag2+ separation. , 2013, Dalton transactions.

[11]  Q. Cui,et al.  Structural phase transitions of SrF2 at high pressure , 2012 .

[12]  Fujio Izumi,et al.  VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data , 2011 .

[13]  Prasanna S. Ghalsasi,et al.  Single crystal X-Ray structure of BeF2: α-quartz. , 2011, Inorganic chemistry.

[14]  Marcin Wojdyr,et al.  Fityk: a general-purpose peak fitting program , 2010 .

[15]  T. Duffy,et al.  Phase Transitions and Equations of State of Alkaline Earth Fluorides CaF2 SrF2 and BaF2 to Mbar Pressures , 2010 .

[16]  Y. Akahama,et al.  Pressure calibration of diamond anvil Raman gauge to 410 GPa , 2010 .

[17]  T. Kikegawa,et al.  Stable phase with the α-PbO2 type structure in MgF2 under high pressure and high temperature , 2008 .

[18]  T. Kikegawa,et al.  In situ X-ray observation of phase transitions in ZnF2 under high pressure and high temperature , 2008 .

[19]  G. Scuseria,et al.  Restoring the density-gradient expansion for exchange in solids and surfaces. , 2007, Physical review letters.

[20]  W. Grochala,et al.  Pressure-induced transformations of AgIIF2—towards an ‘infinite layer’ d9 material , 2007 .

[21]  R. Egdell,et al.  On the covalency of silver-fluorine bonds in compounds of silver(I), silver(II) and silver(III). , 2003, Chemphyschem : a European journal of chemical physics and physical chemistry.

[22]  A. Cassetta,et al.  High-pressure X-ray diffraction study on α-PbF2 , 2003 .

[23]  Zhi-Qiang Li,et al.  X-ray diffraction and theoretical studies of the high-pressure structures and phase transitions in magnesium fluoride , 2001 .

[24]  Z. Mazej,et al.  A new variety of PdF2 synthesised by low-temperature reaction in anhydrous HF , 2001 .

[25]  R. Hoffmann,et al.  Real and Hypothetical Intermediate-Valence AgII /AgIII and AgII /AgI Fluoride Systems as Potential Superconductors. , 2001, Angewandte Chemie.

[26]  K. Leinenweber,et al.  Crystal structure and bonding in the high-pressure form of fluorite (CaF2) , 2001 .

[27]  G. Kresse,et al.  From ultrasoft pseudopotentials to the projector augmented-wave method , 1999 .

[28]  S. Hull,et al.  High-pressure structural behaviour of silver(I) fluoride , 1998 .

[29]  J. Haines,et al.  High-pressure isosymmetric phase transition in orthorhombic lead fluoride , 1998 .

[30]  Yoshiyuki Kawazoe,et al.  First-Principles Determination of the Soft Mode in Cubic ZrO 2 , 1997 .

[31]  Kresse,et al.  Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. , 1996, Physical review. B, Condensed matter.

[32]  G. Kresse,et al.  Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set , 1996 .

[33]  Hafner,et al.  Ab initio molecular dynamics for liquid metals. , 1995, Physical review. B, Condensed matter.

[34]  Haines,et al.  High-pressure x-ray- and neutron-diffraction studies of BaF2: An example of a coordination number of 11 in AX2 compounds. , 1995, Physical review. B, Condensed matter.

[35]  J. Zaanen,et al.  Density-functional theory and strong interactions: Orbital ordering in Mott-Hubbard insulators. , 1995, Physical review. B, Condensed matter.

[36]  Haines,et al.  High-pressure transitions to a postcotunnite phase in ionic AX2 compounds. , 1995, Physical review. B, Condensed matter.

[37]  Hafner,et al.  Ab initio molecular-dynamics simulation of the liquid-metal-amorphous-semiconductor transition in germanium. , 1994, Physical review. B, Condensed matter.

[38]  B. Müller,et al.  Einkristalluntersuchungen an AgF2 , 1990 .

[39]  B. Müller Zur struktur von CaPdF4, CdPdF4, HgPdF4 und HpPdF2 , 1982 .

[40]  J. Soubeyroux,et al.  On a new structural type of fluorine compounds : Crystal and magnetic structures of a high pressure form of PdF2 , 1981 .

[41]  B. Müller Über Hochdruckmodifikationen von Palladiumfluorid und Silberfluorid , 1979, Naturwissenschaften.

[42]  J. Gaazo Plasticity of the coordination sphere of copper(II) complexes, its manifestation and causes , 1976 .

[43]  A. E. Austin High pressure transformations of transition metal difluorides , 1969 .

[44]  J. Kanamori,et al.  Superexchange interaction and symmetry properties of electron orbitals , 1959 .

[45]  John B. Goodenough,et al.  An interpretation of the magnetic properties of the perovskite-type mixed crystals La1-xSrxCoO3-λ , 1958 .

[46]  H. Haendler,et al.  The Crystal Structure of Copper(II) Fluoride , 1957 .

[47]  John B. Goodenough,et al.  Theory of the role of covalence in the perovskite-type manganites [La,M(II)]MnO3 , 1955 .

[48]  W. Bragg The Analysis of Crystals by the X-ray Spectrometer , 1914 .

[49]  A. Romero,et al.  Pressure-induced phase-transition sequence in CoF2: An experimental and first-principles study on the crystal, vibrational, and electronic properties , 2013 .

[50]  K. Houk,et al.  Alternative descriptions of the C23 (PbCl2), C37 (Co2Si), B8b (Ni2In) and related structure types , 1992 .

[51]  A. F. Wells 333. The crystal structure of anhydrous cupric chloride, and the stereochemistry of the cupric atom , 1947 .