Publications by authors named "Boby Joseph"

17 Publications

  • Page 1 of 1

Large scale synthesis of copper nickel alloy nanoparticles with reduced compressibility using arc thermal plasma process.

Sci Rep 2021 Apr 7;11(1):7629. Epub 2021 Apr 7.

Elettra-Sincrotrone Trieste, S.S. 14, Km 163.5 in Area Science Park, 34149, Basovizza, Italy.

Among the various methods employed in the synthesis of nanostructures, those involving high operating temperature and sharp thermal gradients often lead to the establishment of new exotic properties. Herein, we report on the formation of Cu-Ni metallic alloy nanoparticles with greatly enhanced stiffness achieved through direct-current transferred arc-thermal plasma assisted vapour-phase condensation. High pressure synchrotron X-ray powder diffraction (XRPD) at ambient temperature as well as XRPD in the temperature range 180 to 920 K, show that the thermal arc-plasma route resulted in alloy nanoparticles with much enhanced bulk modulus compared to their bulk counterparts. Such a behaviour may find an explanation in the sudden quenching assisted by the retention of a large amount of local strain due to alloying, combined with the perfect miscibility of the elemental components during the thermal plasma synthesis process.
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http://dx.doi.org/10.1038/s41598-021-86776-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8026964PMC
April 2021

Metavalent Bonding in GeSe Leads to High Thermoelectric Performance.

Angew Chem Int Ed Engl 2021 Feb 22. Epub 2021 Feb 22.

New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur P.O., Bangalore, 560064, India.

Orthorhombic GeSe is a promising thermoelectric material. However, large band gap and strong covalent bonding result in a low thermoelectric figure of merit, zT≈0.2. Here, we demonstrate a maximum zT≈1.35 at 627 K in p-type polycrystalline rhombohedral (GeSe) (AgBiTe )  , which is the highest value reported among GeSe based materials. The rhombohedral phase is stable in ambient conditions for x=0.8-0.29 in (GeSe) (AgBiTe )  . The structural transformation accompanies change from covalent bonding in orthorhombic GeSe to metavalent bonding in rhombohedral (GeSe) (AgBiTe )  . (GeSe) (AgBiTe ) has closely lying primary and secondary valence bands (within 0.25-0.30 eV), which results in high power factor 12.8 μW cm  K at 627 K. It also exhibits intrinsically low lattice thermal conductivity (0.38 Wm  K at 578 K). Theoretical phonon dispersion calculations reveal vicinity of a ferroelectric instability, with large anomalous Born effective charges and high optical dielectric constant, which, in concurrence with high effective coordination number, low band gap and moderate electrical conductivity, corroborate metavalent bonding in (GeSe) (AgBiTe ) . We confirmed the presence of low energy phonon modes and local ferroelectric domains using heat capacity measurement (3-30 K) and switching spectroscopy in piezoresponse force microscopy, respectively.
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http://dx.doi.org/10.1002/anie.202101283DOI Listing
February 2021

Crystal structure of monoclinic hafnia (HfO) revisited with synchrotron X-ray, neutron diffraction and first-principles calculations.

Acta Crystallogr C Struct Chem 2020 Nov 29;76(Pt 11):1034-1042. Epub 2020 Oct 29.

UGC-DAE Consortium for Scientific Research, 246C, CFB, Bhabha Atomic Research Centre, Mumbai 400 085, India.

A study on the crystal structure of monoclinic HfO has been performed using synchrotron X-ray and neutron diffraction data separately, as well as a combination of both. The precision of the structural parameters increases significantly due to application of the neutron diffraction technique. The experimental oxygen positions in HfO, derived precisely, are visualized only by semi-local density functional calculations in terms of the calculated electronic band gap, but are not captured as accurately by using hybrid functionals.
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http://dx.doi.org/10.1107/S2053229620013960DOI Listing
November 2020

Correction to "Porous Organic Polymer-Driven Evolution of High-Performance Cobalt Phosphide Hybrid Nanosheets as Vanillin Hydrodeoxygenation Catalyst".

ACS Appl Mater Interfaces 2020 Oct 1;12(41):47110. Epub 2020 Oct 1.

Catalysis & Fine Chemicals Division, CSIR-Indian Institute of Chemical Technology, Uppal Road, Hyderabad 500 007, India.

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http://dx.doi.org/10.1021/acsami.0c16071DOI Listing
October 2020

Mesoporous Metal-Organic Framework MIL-101 at High Pressure.

J Am Chem Soc 2020 Sep 19;142(35):15012-15019. Epub 2020 Aug 19.

Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, 91192 Cedex Gif sur Yvette, France.

The chromium terephthalate MIL-101 is a mesoporous metal-organic framework (MOF) with unprecedented adsorption capacities due to the presence of giant pores. The application of an external pressure can effectively modify the open structure of MOFs and its interaction with guest molecules. In this work, we study MIL-101 under pressure by synchrotron X-ray diffraction and infrared (IR) spectroscopy with several pressure transmitting media (PTM). Our experimental results clearly show that when a solid medium as NaCl is employed, an irreversible amorphization of the empty structure occurs at about 0.4 GPa. Using a fluid PTM, as Nujol or high-viscosity silicone oil, results in a slight lattice expansion and a strong modification of the peak frequency and shape of the MOF hydroxyl vibration below 0.1 GPa. Moreover, the framework stability is enhanced under pressure with the amorphization onset shifted to about 7 GPa. This coherent set of results points out the insertion of the fluid inside the MIL-101 pores. Above 7 GPa, concomitantly to the nucleation of the amorphous phase, we observe a peculiar medium-dependent lattice expansion. The behavior of the OH stretching vibrations under pressure is profoundly affected by the presence of the guest fluid, showing that OH bonds are sensitive vibrational probes of the host-guest interactions. The present study demonstrates that even a polydimethylsiloxane silicone oil, although highly viscous, can be effectively inserted into the MIL-101 pores at a pressure below 0.2 GPa. High pressure can thus promote the incorporation of large polymers in mesoporous MOFs.
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http://dx.doi.org/10.1021/jacs.0c05882DOI Listing
September 2020

Leveraging Cu/CuFeO-Catalyzed Biomass-Derived Furfural Hydrodeoxygenation: A Nanoscale Metal-Organic-Framework Template Is the Prime Key.

ACS Appl Mater Interfaces 2020 May 30;12(19):21682-21700. Epub 2020 Apr 30.

Catalysis & Fine Chemicals Division, CSIR-Indian Institute of Chemical Technology, Uppal Road, Hyderabad 500 007, India.

Enormous efforts have been initiated in the production of biobased fuels and value-added chemicals biorefinery owing to the scarcity of fossil resources and huge environmental synchronization. Herein, non-noble metal-based metal/mixed metal oxide supported on carbon employing a metal-organic framework as a sacrificial template is demonstrated for the first time in the selective hydrodeoxygenation (HDO) of biomass-derived furfural (FFR) to 2-methyl furan (MF). The aforementioned catalyst (referred to as Cu/CuFeO@C-) exhibited extraordinary catalytic proficiency (100% selectivity toward MF) compared with the conventional Cu/CuFeO@C- catalyst which was prepared by the wet impregnation method. High-resolution transmission electron microscopy and synchrotron X-ray diffraction studies evidenced the existence of both metal (Cu) and mixed metal oxide (CuFeO) phases, in which the metal could help in hydrogenation to alcohol and metal oxide could assist in the hydroxyl group removal step during HDO reaction. The stabilization of encapsulated metal/metal oxide nanoparticles in the carbon matrix, modulation of the electronic structure, and regulation of geometric effects in the Cu/CuFeO@C- are thought to play an important role in its excellent catalytic performance, confirmed by X-ray photoelectron spectroscopy and X-ray absorption spectroscopy investigations. Furthermore, the structure and activity interconnection was confirmed by attenuated total reflection-IR studies, which manifested the strong interfacial interaction between FFR and the Cu/CuFeO@C- catalyst. This finding was further supported by NH temperature-programmed desorption analysis, which suggested that the presence of more Lewis/weak acidic sites in this catalyst was beneficial for the hydrogenolysis step in HDO reaction. Additionally, H temperature-programmed reduction studies revealed that the adsorption of H was stronger on the Cu/CuFeO@C- than that over the conventional Cu/CuFeO@C- catalyst; thus, the former catalyst promoted activation of H. A detailed kinetic analysis which demonstrated the lower activation energy barrier along with dual active sites attributed for the activation of the two separate reactions in the HDO process on the Cu/CuFeO@C- catalyst. This work has great implication in developing a highly stable catalyst for the selective upgradation of biomass without deactivation of metal sites in extended catalytic cycles and opens the door of opportunity for developing a sustainably viable catalyst in biomass refinery industries.
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http://dx.doi.org/10.1021/acsami.0c03683DOI Listing
May 2020

Single-crystal diffraction at the high-pressure Indo-Italian beamline Xpress at Elettra, Trieste.

J Synchrotron Radiat 2020 Jan 1;27(Pt 1):222-229. Epub 2020 Jan 1.

Elettra Sincrotrone Trieste ScPA, Strada Statale 14, km 163.5, Basovizza, 34149 Trieste, Italy.

In this study the first in situ high-pressure single-crystal X-ray diffraction experiments at Xpress, the Indo-Italian beamline of the Elettra synchrotron, Trieste (Italy), are reported. A description of the beamline experimental setup and of the procedures for single-crystal centring, data collection and processing, using diamond anvil cells, are provided. High-pressure experiments on a synthetic crystal of clinoenstatite (MgSiO), CaCO polymorphs and a natural sample of leucophoenicite [MnSiO(OH)] validated the suitability of the beamline experimental setup to: (i) locate and characterize pressure-induced phase transitions; (ii) solve ab initio the crystal structure of high-pressure polymorphs; (iii) perform fine structural analyses at the atomic scale as a function of pressure; (iv) disclose complex symmetry and structural features undetected using conventional X-ray sources.
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http://dx.doi.org/10.1107/S1600577519015170DOI Listing
January 2020

Combined micro X-ray absorption and fluorescence spectroscopy to map phases of complex systems: the case of sphalerite.

Sci Rep 2019 12 11;9(1):18857. Epub 2019 Dec 11.

CELLS-ALBA, Carrer de la llum 2-26, Cerdanyola del Valles, 08290, Barcelona, Spain.

Combining micro-X-ray absorption spectroscopy (μXAS) and micro-X-ray fluorescence spectroscopy (μXRF) is a promising approach for the investigation of complex multi-phase systems. In this work, we have employed this approach to investigate natural sphalerite, the most common form of Zinc Sulfide. Spatially resolved elemental distribution maps of common 3d metal atoms (Zn, Cu, Ni, Co, and Fe) are superimposed with chemical speciation and structural parameter maps in order to understand the sphaleriteore-formation process and metamorphosis. Chemical speciation and structural parameters have been obtained by analyzing the μXAS spectra collected in several representative points of the sample, after μXRF mapping. In the present case, this X-ray based approach has permitted to determine the spatial distribution of the Zn species in sphalerite. The presence of two main zincite and smithsonite inclusions has been established, with the latter located close to copper impurity center. Since copper is known to remarkably reduce the corrosion resistance of zinc, resulting in the formation of carbonate as the corrosion product, this implies a possible role of Cu in the growth of the carbonate inclusions. The results obtained highlight the efficiency of this method in univocally identifying the spatial distribution of phases in complex systems, thanks to the simultaneous access to complementary information.
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http://dx.doi.org/10.1038/s41598-019-55347-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6906441PMC
December 2019

Covalent Organic Framework (COF-1) under High Pressure.

Angew Chem Int Ed Engl 2020 Jan 2;59(3):1087-1092. Epub 2019 Dec 2.

Department of Physics, Umeå University, 90187, Umeå, Sweden.

COF-1 has a structure with rigid 2D layers composed of benzene and B O rings and weak van der Waals bonding between the layers. The as-synthesized COF-1 structure contains pores occupied by solvent molecules. A high surface area empty-pore structure is obtained after vacuum annealing. High-pressure XRD and Raman experiments with mesitylene-filled (COF-1-M) and empty-pore COF-1 demonstrate partial amorphization and collapse of the framework structure above 12-15 GPa. The ambient pressure structure of COF-1-M can be reversibly recovered after compression up to 10-15 GPa. Remarkable stability of highly porous COF-1 structure at pressures at least up to 10 GPa is found even for the empty-pore structure. The bulk modulus of the COF-1 structure (11.2(5) GPa) and linear incompressibilities (k =111(5) GPa, k =15.0(5) GPa) were evaluated from the analysis of XRD data and cross-checked against first-principles calculations.
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http://dx.doi.org/10.1002/anie.201907689DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7065212PMC
January 2020

Effect of HO on the Pressure-Induced Amorphization of Hydrated AlPO-17.

Molecules 2019 Aug 7;24(16). Epub 2019 Aug 7.

ICGM, CNRS, Université de Montpellier, ENSCM, 4095 Montpellier, France.

The incorporation of guest species in zeolites has been found to strongly modify their mechanical behavior and their stability with respect to amorphization at high pressure (HP). Here we report the strong effect of HO on the pressure-induced amorphization (PIA) in hydrated AlPO-17. The material was investigated in-situ at HP by synchrotron X-ray powder diffraction in diamond anvil cells by using non- and penetrating pressure transmitting media (PTM), respectively, silicone oil and HO. Surprisingly, in non-penetrating PTM, its structural response to pressure was similar to its anhydrous phase at lower pressures up to ~1.4 GPa, when the amorphization was observed to start. Compression of the structure of AlPO-17 is reduced by an order of magnitude when the material is compressed in HO, in which amorphization begins in a similar pressure range as in non-penetrating PTM. The complete and irreversible amorphization was observed at ~9.0 and ~18.7 GPa, respectively, in non- and penetrating PTM. The present results show that the insertion of guest species can be used to strongly modify the stability of microporous material with respect to PIA, by up to an order of magnitude.
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http://dx.doi.org/10.3390/molecules24162864DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6720878PMC
August 2019

Porous Organic Polymer-Driven Evolution of High-Performance Cobalt Phosphide Hybrid Nanosheets as Vanillin Hydrodeoxygenation Catalyst.

ACS Appl Mater Interfaces 2019 Jul 26;11(27):24140-24153. Epub 2019 Jun 26.

Catalysis & Fine Chemicals Division , CSIR-Indian Institute of Chemical Technology , Uppal Road , Hyderabad 500 007 , India.

Hydrodeoxygenation (HDO) is a promising route for the upgrading of bio-oils to eco-friendly biofuel produced from lignocellulose. Herein, we report the sequential synthesis of a hybrid nanocatalyst CoP@POP, where substoichiometric CoP nanoparticles are distributed in a porous organic polymer (POP) via solid-state phosphidation of the CoO@POP nanohybrid system. We also explored the catalytic activity of the above two nanohybrids toward the HDO of vanillin, a typical compound of lignin-derived bio-oil to 2-methoxy-4-methylphenol, which is a promising future biofuel. The CoP@POP exhibited superior catalytic activity and selectivity toward desired product with improved stability compared to the CoO@POP. Based on advanced sample characterization results, the extraordinary selectivity of CoP@POP is attributed to the strong interaction of the cation of the CoP nanoparticle with the POP matrix and the consequent modifications of the electronic states. Through attenuated total reflectance-infrared spectroscopy, we have also observed different interaction strengths between vanillin and the two catalysts. The decreased catalytic activity of CoO@POP compared to CoP@POP catalyst could be attributed to the stronger adsorption of vanillin over the CoO@POP catalyst. Also from kinetic investigation, it is clearly demonstrated that the CoO@POP has higher activation energy barrier than the CoP@POP, which also reflects to the reduction of the overall efficiency of the CoO@POP catalyst. To the best of our knowledge, this is the first approach in POP-encapsulated cobalt phosphide catalyst synthesis and comprehensive study in establishing the structure-activity relationship in significant step-forwarding in promoting biomass refining.
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http://dx.doi.org/10.1021/acsami.9b06789DOI Listing
July 2019

Determination of the local structure of SrMIrO (M = K, La) as a function of doping and temperature.

Phys Chem Chem Phys 2018 Sep;20(36):23783-23788

Research Institute for Interdisciplinary Science, Okayama University, Okayama, 700-8530, Japan.

The local structure of correlated spin-orbit insulator Sr2-xMxIrO4 (M = K, La) has been investigated by Ir L3-edge extended X-ray absorption fine structure measurements. The measurements were performed as a function of temperature for different dopings induced by substitution of Sr with La or K. It is found that Ir-O bonds have strong covalency and they hardly show any change across the Néel temperature. In the studied doping range, neither Ir-O bonds nor their dynamics, measured by their mean square relative displacements, show any appreciable change upon carrier doping, indicating the possibility of nanoscale phase separation in the doped system. On the other hand, there is a large increase of the static disorder in Ir-Sr correlation, larger for K doping than La doping. Similarities and differences with respect to the local lattice displacements in cuprates are briefly discussed.
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http://dx.doi.org/10.1039/c8cp03756fDOI Listing
September 2018

Nanocluster superstructures or nanoparticles? The self-consuming scaffold decides.

Nanoscale 2018 Apr;10(16):7472-7483

ISM-CNR, Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo Scalo, RM, Italy.

We show that using the same reaction procedure, by hindering or allowing the formation of a reaction intermediate, the Ag+dodecanethiolate polymeric complex, it is possible to selectively obtain Ag dodecanethiolate nanoparticles or Ag dodecanethiolate nanoclusters in the size range 4-2 nm. Moreover, the Ag dodecanethiolate nanoclusters display a lamellar superstructure templated from the precursor Ag+dodecanethiolate polymeric complex. A plausible formation mechanism is illustrated where, starting from the precursor and scaffold lamellar Ag+ thiolate polymeric complex, first the nanocluster Agn0 core is formed by reduction of isoplanar Ag+ ions, followed by Ag+ thiolate units that build protection, the nanocluster shell, around the core. The nanoclusters are characterized by elemental analyses, XRD, ATR-FTIR, XPS, XAS, MALDI, ESI, UV-Vis and fluorescence measurements. The luminescent Ag15(dodecanethiolate)11·2H2O nanocluster is achieved in good yield after 4 hours of reaction whereas after 2 hours, the luminescent Ag35(dodecanethiolate)16 is isolated. Both Ag nanoclusters present emission bands in the range 330-450 nm, the shifting depending on the excitation wavelength. This phenomenon is attributed to a possible dipolar state causing distribution in energies due to variability of dipole-dipole interactions. Moreover, both nanoclusters further present a NIR emission at about 700 nm independent from the excitation wavelength. Thanks to their optical and structural properties, the synthesized nanoclusters, perfect molecular/nanoparticle hybrids, have great potentiality for new applications in nanotechnologies.
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http://dx.doi.org/10.1039/c7nr09520aDOI Listing
April 2018

Synthetically Tuned Atomic Ordering in PdCu Nanoparticles with Enhanced Catalytic Activity toward Solvent-Free Benzylamine Oxidation.

ACS Appl Mater Interfaces 2017 Feb 23;9(4):3602-3615. Epub 2017 Jan 23.

New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064, India.

Synthesis of ordered compounds with nano size is of particular interest for tuning the surface properties with enhanced activity and selectivity toward various important industrial catalytic processes. In this work, we synthesized ordered PdCu nanoparticles as highly efficient catalyst for the solvent-free aerobic oxidation of benzylamine. The PdCu catalysts with different chemical compositions (x = 0, 0.25, 0.4, 0.5, 0.6, 0.75, 1) were prepared by polyol method using NaBH as a reducing agent and were well-characterized by X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM) energy-dispersive analysis of X-rays, and X-ray absorption fine structure. The effect of different metal concentrations of Pd and Cu on the formation of PdCu nanoparticles was investigated. The XRD and TEM confirmed the formation of ordered PdCu intermetallic phase with body-centered cubic (BCC) structure for the synthetic composition of Pd/Cu = 1:1. For compositions x = 0, 0.25, 0.75, and 1, PdCu alloy with face-centered cubic (FCC) structure was observed, whereas mixed phase of BCC and FCC was observed for x = 0.4 and 0.6. The use of strong reducing agent (NaBH) was essential to synthesize PdCu ordered phase compared to weak reducing agents such as oleylamine and ascorbic acid. The PdCu nanocatalyst with ordered structure (BCC) showed excellent catalytic activity compared to PdCu alloy nanoparticles with FCC structure. The atomic ordering in the PdCu intermetallic was the driving force for the enhancement in the catalytic activity with high benzylamine conversion of 94.0% and dibenzylimine selectivity of 92.2% compared to its monometallic and alloy counterparts. Moreover, ordered PdCu alloy showed good recyclability and activity toward the oxidation of different amines.
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http://dx.doi.org/10.1021/acsami.6b12253DOI Listing
February 2017

CHNHPbI, A Potential Solar Cell Candidate: Structural and Spectroscopic Investigations.

J Phys Chem A 2016 Dec 5;120(49):9732-9739. Epub 2016 Dec 5.

Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005, Odisha, India.

Hybrid organic-inorganic metal halides of the type CHNHPbX have emerged as potential materials for photovoltaic applications. In this paper we discuss structural, electronic, and optical spectroscopy investigations performed on high quality single crystals of CHNHPbI. Our results conclusively suggest that CHNHPbI crystallizes in centrosymmetric space group and the methylammonium moiety exhibits disordered packing at room temperature. Extracted values of the exciton binding energy, the electron-phonon coupling constant, and the schematic energy level diagram constructed from the emission broadening, Raman, and photoemission spectroscopy measurements clearly show the potential of this system in photovoltaic applications.
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http://dx.doi.org/10.1021/acs.jpca.6b09718DOI Listing
December 2016

Local structural investigation of SmFeAsO₁₋xF(x) high temperature superconductors.

J Phys Condens Matter 2011 Jul 10;23(27):272201. Epub 2011 Jun 10.

Dipartimento di Chimica-Sezione di Chimica Fisica, INSTM (UdR Pavia), Università di Pavia, Viale Taramelli 16, 27100 Pavia, Italy.

A strong revitalization of the field of high temperature superconductivity (HTSC) has been induced recently by the discovery of T(C) around 26 K in F-doped LaFeAsO iron pnictides. Starting from this discovery, a huge amount of experimental data have been accumulated. This important corpus of results will allow the development of suitable theoretical models aimed at describing the basic electronic structure properties and nature of superconducting states in these fascinating new systems. A close correlation between structural features and physical properties of the normal and superconducting states has already been demonstrated in the current literature. Advanced theoretical models are also based on the close correlation with structural properties and in particular with the Fe-As tetrahedral array. As for other complex materials, a deeper understanding of their structure-properties correlation requires a full knowledge of the atomic arrangement within the structure. Here we report an investigation of the local structure in the SmFeAsO₁₋ xF(x) system carried out by means of x-ray total scattering measurements and pair distribution function analysis. The results presented indicate that the local structure of these HTSC significantly differs from the average structure determined by means of traditional diffraction techniques, in particular the distribution of Fe-As bond lengths. In addition, a model for describing the observed discrepancies is presented.
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http://dx.doi.org/10.1088/0953-8984/23/27/272201DOI Listing
July 2011

Pressure effects in the isoelectronic REFe0.85Ir0.15AsO system.

J Am Chem Soc 2011 Mar 22;133(10):3252-5. Epub 2011 Feb 22.

Department of Chemistry, and INSTM Unit of Pavia, viale Taramelli 10/16, 27100 Pavia, Italy.

The effect of chemical and hydrostatic pressure has been studied systematically in a selected system belonging to the 1111 family of iron pnictide high-temperature superconductors. The results show a surprising similarity between the trend of critical temperature vs hydrostatic pressure for isoelectronic samples with different rare earths (RE) on the RE site and samples of the SmFeAsO(1-x)F(x) series with different doping levels. These results open new questions about the underlying mechanism for superconductivity in iron pnictides.
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http://dx.doi.org/10.1021/ja1098808DOI Listing
March 2011