13 research outputs found

    Extension of Rietveld Refinement for Benchtop Powder XRD Analysis of Ultrasmall Supported Nanoparticles

    No full text
    We present a method for characterizing ultrasmall (<2 nm) supported crystallites with benchtop XRD. Central to the method is an understanding of the intensity effects at play; these intensity effects and their corrections are discussed in depth. Background subtractionlong considered one of the main barriers to ultrasmall crystal characterizationis solved by correcting the diffractogram of a separately measured support for the relevant intensity effects. Rietveld refinement is demonstrated to be an adequate analysis method for the general characterization of simple nanosystems. A 4.8% Pt/SiO2 sample (1.3 nm, volume-weighted average) is used as a case study; it is found that the Pt spontaneously oxidizes under ambient conditions and consists of a metallic core surrounded by a PtO2 shell. Both phases have average dimensions smaller than 1 nm. The XRD results also suggest lattice expansion of the Pt core as compared to bulk Pt

    Extension of Rietveld Refinement for Benchtop Powder XRD Analysis of Ultrasmall Supported Nanoparticles

    No full text
    We present a method for characterizing ultrasmall (<2 nm) supported crystallites with benchtop XRD. Central to the method is an understanding of the intensity effects at play; these intensity effects and their corrections are discussed in depth. Background subtractionlong considered one of the main barriers to ultrasmall crystal characterizationis solved by correcting the diffractogram of a separately measured support for the relevant intensity effects. Rietveld refinement is demonstrated to be an adequate analysis method for the general characterization of simple nanosystems. A 4.8% Pt/SiO2 sample (1.3 nm, volume-weighted average) is used as a case study; it is found that the Pt spontaneously oxidizes under ambient conditions and consists of a metallic core surrounded by a PtO2 shell. Both phases have average dimensions smaller than 1 nm. The XRD results also suggest lattice expansion of the Pt core as compared to bulk Pt

    Extension of Rietveld Refinement for Benchtop Powder XRD Analysis of Ultrasmall Supported Nanoparticles

    No full text
    We present a method for characterizing ultrasmall (<2 nm) supported crystallites with benchtop XRD. Central to the method is an understanding of the intensity effects at play; these intensity effects and their corrections are discussed in depth. Background subtractionlong considered one of the main barriers to ultrasmall crystal characterizationis solved by correcting the diffractogram of a separately measured support for the relevant intensity effects. Rietveld refinement is demonstrated to be an adequate analysis method for the general characterization of simple nanosystems. A 4.8% Pt/SiO2 sample (1.3 nm, volume-weighted average) is used as a case study; it is found that the Pt spontaneously oxidizes under ambient conditions and consists of a metallic core surrounded by a PtO2 shell. Both phases have average dimensions smaller than 1 nm. The XRD results also suggest lattice expansion of the Pt core as compared to bulk Pt

    Extension of Rietveld Refinement for Benchtop Powder XRD Analysis of Ultrasmall Supported Nanoparticles

    No full text
    We present a method for characterizing ultrasmall (<2 nm) supported crystallites with benchtop XRD. Central to the method is an understanding of the intensity effects at play; these intensity effects and their corrections are discussed in depth. Background subtractionlong considered one of the main barriers to ultrasmall crystal characterizationis solved by correcting the diffractogram of a separately measured support for the relevant intensity effects. Rietveld refinement is demonstrated to be an adequate analysis method for the general characterization of simple nanosystems. A 4.8% Pt/SiO2 sample (1.3 nm, volume-weighted average) is used as a case study; it is found that the Pt spontaneously oxidizes under ambient conditions and consists of a metallic core surrounded by a PtO2 shell. Both phases have average dimensions smaller than 1 nm. The XRD results also suggest lattice expansion of the Pt core as compared to bulk Pt

    Atomic Layer Deposition of Transparent and Conducting p‑Type Cu(I) Incorporated ZnS Thin Films: Unravelling the Role of Compositional Heterogeneity on Optical and Carrier Transport Properties

    No full text
    Optically transparent and highly conducting p-type Cu­(I) incorporated ZnS (Cu:ZnS) films are deposited by stacking individual layers of CuS and ZnS using atomic layer deposition. The deposition chemistry and growth mechanism are studied by in situ quartz crystal microbalance. Compositional disorder in atomic scale is observed with increasing Cu incorporation in the films that results in systematic decrease in the optical transmittance in the visible spectrum. Again the conductivity also emphatically depends on the volume fraction of phase-segregated conducting covellite phase. An illustrious correlation prevailing the interplay between the optical transparency and the charge transport mechanism is established. The hole transport mechanism that indicates insulator-to-metal transition with increasing Cu incorporation in the composite is explained in terms of an inhomogeneously disordered system. Under optimized conditions, the material having moderately high optical transmission with degenerate carrier concentration lies exactly at the confluence between the metallic and insulating regime. The lowest resistivity that is obtained here (1.3 × 10<sup>–3</sup> Ω cm) with >90% (after reflection correction) transmission is highly comparable to the best ones that are reported in the field and probably analogous to the commercially available n-type transparent conductors

    Extension of Rietveld Refinement for Benchtop Powder XRD Analysis of Ultrasmall Supported Nanoparticles

    No full text
    We present a method for characterizing ultrasmall (<2 nm) supported crystallites with benchtop XRD. Central to the method is an understanding of the intensity effects at play; these intensity effects and their corrections are discussed in depth. Background subtractionlong considered one of the main barriers to ultrasmall crystal characterizationis solved by correcting the diffractogram of a separately measured support for the relevant intensity effects. Rietveld refinement is demonstrated to be an adequate analysis method for the general characterization of simple nanosystems. A 4.8% Pt/SiO2 sample (1.3 nm, volume-weighted average) is used as a case study; it is found that the Pt spontaneously oxidizes under ambient conditions and consists of a metallic core surrounded by a PtO2 shell. Both phases have average dimensions smaller than 1 nm. The XRD results also suggest lattice expansion of the Pt core as compared to bulk Pt

    Extension of Rietveld Refinement for Benchtop Powder XRD Analysis of Ultrasmall Supported Nanoparticles

    No full text
    We present a method for characterizing ultrasmall (<2 nm) supported crystallites with benchtop XRD. Central to the method is an understanding of the intensity effects at play; these intensity effects and their corrections are discussed in depth. Background subtractionlong considered one of the main barriers to ultrasmall crystal characterizationis solved by correcting the diffractogram of a separately measured support for the relevant intensity effects. Rietveld refinement is demonstrated to be an adequate analysis method for the general characterization of simple nanosystems. A 4.8% Pt/SiO2 sample (1.3 nm, volume-weighted average) is used as a case study; it is found that the Pt spontaneously oxidizes under ambient conditions and consists of a metallic core surrounded by a PtO2 shell. Both phases have average dimensions smaller than 1 nm. The XRD results also suggest lattice expansion of the Pt core as compared to bulk Pt

    Extension of Rietveld Refinement for Benchtop Powder XRD Analysis of Ultrasmall Supported Nanoparticles

    No full text
    We present a method for characterizing ultrasmall (<2 nm) supported crystallites with benchtop XRD. Central to the method is an understanding of the intensity effects at play; these intensity effects and their corrections are discussed in depth. Background subtractionlong considered one of the main barriers to ultrasmall crystal characterizationis solved by correcting the diffractogram of a separately measured support for the relevant intensity effects. Rietveld refinement is demonstrated to be an adequate analysis method for the general characterization of simple nanosystems. A 4.8% Pt/SiO2 sample (1.3 nm, volume-weighted average) is used as a case study; it is found that the Pt spontaneously oxidizes under ambient conditions and consists of a metallic core surrounded by a PtO2 shell. Both phases have average dimensions smaller than 1 nm. The XRD results also suggest lattice expansion of the Pt core as compared to bulk Pt

    Extension of Rietveld Refinement for Benchtop Powder XRD Analysis of Ultrasmall Supported Nanoparticles

    No full text
    We present a method for characterizing ultrasmall (<2 nm) supported crystallites with benchtop XRD. Central to the method is an understanding of the intensity effects at play; these intensity effects and their corrections are discussed in depth. Background subtractionlong considered one of the main barriers to ultrasmall crystal characterizationis solved by correcting the diffractogram of a separately measured support for the relevant intensity effects. Rietveld refinement is demonstrated to be an adequate analysis method for the general characterization of simple nanosystems. A 4.8% Pt/SiO2 sample (1.3 nm, volume-weighted average) is used as a case study; it is found that the Pt spontaneously oxidizes under ambient conditions and consists of a metallic core surrounded by a PtO2 shell. Both phases have average dimensions smaller than 1 nm. The XRD results also suggest lattice expansion of the Pt core as compared to bulk Pt

    Extension of Rietveld Refinement for Benchtop Powder XRD Analysis of Ultrasmall Supported Nanoparticles

    No full text
    We present a method for characterizing ultrasmall (<2 nm) supported crystallites with benchtop XRD. Central to the method is an understanding of the intensity effects at play; these intensity effects and their corrections are discussed in depth. Background subtractionlong considered one of the main barriers to ultrasmall crystal characterizationis solved by correcting the diffractogram of a separately measured support for the relevant intensity effects. Rietveld refinement is demonstrated to be an adequate analysis method for the general characterization of simple nanosystems. A 4.8% Pt/SiO2 sample (1.3 nm, volume-weighted average) is used as a case study; it is found that the Pt spontaneously oxidizes under ambient conditions and consists of a metallic core surrounded by a PtO2 shell. Both phases have average dimensions smaller than 1 nm. The XRD results also suggest lattice expansion of the Pt core as compared to bulk Pt
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