The Experts below are selected from a list of 183 Experts worldwide ranked by ideXlab platform

Rolf D Neuser - One of the best experts on this subject based on the ideXlab platform.

  • from tabular to rhombohedral dolomite crystals in zechstein 2 dolostones from scharzfeld sw harz germany a case study with combined cl and ebsd investigations
    Sedimentary Geology, 2010
    Co-Authors: Axel Gillhaus, Detlev K Richter, Thomas Gotte, Rolf D Neuser
    Abstract:

    Abstract Tabular dolomite crystals found within dolomite rhombs have been investigated by cathodoluminescence (CL) microscopy and spectroscopy combined with electron backscatter diffraction (EBSD) for the first time. The dolomites formed in the Upper Permian Stassfurt Carbonate Ca2 at the southern margin of the German/Polish Zechstein Basin. Cathodoluminescence petrography of the dolostone succession revealed that the dolomites developed in four phases. Electron backscatter diffraction analysis reveals tabular crystal growth during the two first generations, while the last two generations are characterized by rhombohedral crystal shapes. The tabular dolomite cement crystals and their microcrystalline equivalents in matrix and components have a stoichiometric comPosition with good to very good Lattice ordering. Manganese and iron contents of the tabular crystals are low and their carbon and oxygen isotope comPosition confirms an early diagenetic dolomite formation under marine-evaporitic conditions from precursor carbonates of Upper Permian age. CL spectroscopy reveals that the tabular dolomite generation 1 has a very high percentage of Mn2+ on the Ca Lattice Position which results in a visually yellowish-green CL emission. Although relatively increased Mn2+ contents at the Ca Lattice Position appear to be rather common in evaporitic dolomites the combination of a tabular crystal shape and a preferred input of Mn2+ at the Ca Lattice Position is a remarkable phenomenon. As tabular dolomite crystals so far are exclusively reported from evaporitic diagenetic settings they could be the result of a high Mg/Ca ratio which blocks c-axis orientated growth of dolomite crystal. The occurrence of well ordered dolomite of which the geochemical zoning can be studied in such detail is rare for the earliest, synsedimentary stages of dolomite formation in marine environments, because these early stages commonly consist of not or badly ordered Ca-dolomites. A primary geochemical zoning of such dolomite usually gets lost during stabilisation and transformation to better ordering and stoichiometry.

  • From tabular to rhombohedral dolomite crystals in Zechstein 2 dolostones from Scharzfeld (SW Harz/Germany): A case study with combined CL and EBSD investigations
    Sedimentary Geology, 2010
    Co-Authors: Axel Gillhaus, Detlev K Richter, Thomas Gotte, Rolf D Neuser
    Abstract:

    Abstract Tabular dolomite crystals found within dolomite rhombs have been investigated by cathodoluminescence (CL) microscopy and spectroscopy combined with electron backscatter diffraction (EBSD) for the first time. The dolomites formed in the Upper Permian Stassfurt Carbonate Ca2 at the southern margin of the German/Polish Zechstein Basin. Cathodoluminescence petrography of the dolostone succession revealed that the dolomites developed in four phases. Electron backscatter diffraction analysis reveals tabular crystal growth during the two first generations, while the last two generations are characterized by rhombohedral crystal shapes. The tabular dolomite cement crystals and their microcrystalline equivalents in matrix and components have a stoichiometric comPosition with good to very good Lattice ordering. Manganese and iron contents of the tabular crystals are low and their carbon and oxygen isotope comPosition confirms an early diagenetic dolomite formation under marine-evaporitic conditions from precursor carbonates of Upper Permian age. CL spectroscopy reveals that the tabular dolomite generation 1 has a very high percentage of Mn2+ on the Ca Lattice Position which results in a visually yellowish-green CL emission. Although relatively increased Mn2+ contents at the Ca Lattice Position appear to be rather common in evaporitic dolomites the combination of a tabular crystal shape and a preferred input of Mn2+ at the Ca Lattice Position is a remarkable phenomenon. As tabular dolomite crystals so far are exclusively reported from evaporitic diagenetic settings they could be the result of a high Mg/Ca ratio which blocks c-axis orientated growth of dolomite crystal. The occurrence of well ordered dolomite of which the geochemical zoning can be studied in such detail is rare for the earliest, synsedimentary stages of dolomite formation in marine environments, because these early stages commonly consist of not or badly ordered Ca-dolomites. A primary geochemical zoning of such dolomite usually gets lost during stabilisation and transformation to better ordering and stoichiometry.

Axel Gillhaus - One of the best experts on this subject based on the ideXlab platform.

  • from tabular to rhombohedral dolomite crystals in zechstein 2 dolostones from scharzfeld sw harz germany a case study with combined cl and ebsd investigations
    Sedimentary Geology, 2010
    Co-Authors: Axel Gillhaus, Detlev K Richter, Thomas Gotte, Rolf D Neuser
    Abstract:

    Abstract Tabular dolomite crystals found within dolomite rhombs have been investigated by cathodoluminescence (CL) microscopy and spectroscopy combined with electron backscatter diffraction (EBSD) for the first time. The dolomites formed in the Upper Permian Stassfurt Carbonate Ca2 at the southern margin of the German/Polish Zechstein Basin. Cathodoluminescence petrography of the dolostone succession revealed that the dolomites developed in four phases. Electron backscatter diffraction analysis reveals tabular crystal growth during the two first generations, while the last two generations are characterized by rhombohedral crystal shapes. The tabular dolomite cement crystals and their microcrystalline equivalents in matrix and components have a stoichiometric comPosition with good to very good Lattice ordering. Manganese and iron contents of the tabular crystals are low and their carbon and oxygen isotope comPosition confirms an early diagenetic dolomite formation under marine-evaporitic conditions from precursor carbonates of Upper Permian age. CL spectroscopy reveals that the tabular dolomite generation 1 has a very high percentage of Mn2+ on the Ca Lattice Position which results in a visually yellowish-green CL emission. Although relatively increased Mn2+ contents at the Ca Lattice Position appear to be rather common in evaporitic dolomites the combination of a tabular crystal shape and a preferred input of Mn2+ at the Ca Lattice Position is a remarkable phenomenon. As tabular dolomite crystals so far are exclusively reported from evaporitic diagenetic settings they could be the result of a high Mg/Ca ratio which blocks c-axis orientated growth of dolomite crystal. The occurrence of well ordered dolomite of which the geochemical zoning can be studied in such detail is rare for the earliest, synsedimentary stages of dolomite formation in marine environments, because these early stages commonly consist of not or badly ordered Ca-dolomites. A primary geochemical zoning of such dolomite usually gets lost during stabilisation and transformation to better ordering and stoichiometry.

  • From tabular to rhombohedral dolomite crystals in Zechstein 2 dolostones from Scharzfeld (SW Harz/Germany): A case study with combined CL and EBSD investigations
    Sedimentary Geology, 2010
    Co-Authors: Axel Gillhaus, Detlev K Richter, Thomas Gotte, Rolf D Neuser
    Abstract:

    Abstract Tabular dolomite crystals found within dolomite rhombs have been investigated by cathodoluminescence (CL) microscopy and spectroscopy combined with electron backscatter diffraction (EBSD) for the first time. The dolomites formed in the Upper Permian Stassfurt Carbonate Ca2 at the southern margin of the German/Polish Zechstein Basin. Cathodoluminescence petrography of the dolostone succession revealed that the dolomites developed in four phases. Electron backscatter diffraction analysis reveals tabular crystal growth during the two first generations, while the last two generations are characterized by rhombohedral crystal shapes. The tabular dolomite cement crystals and their microcrystalline equivalents in matrix and components have a stoichiometric comPosition with good to very good Lattice ordering. Manganese and iron contents of the tabular crystals are low and their carbon and oxygen isotope comPosition confirms an early diagenetic dolomite formation under marine-evaporitic conditions from precursor carbonates of Upper Permian age. CL spectroscopy reveals that the tabular dolomite generation 1 has a very high percentage of Mn2+ on the Ca Lattice Position which results in a visually yellowish-green CL emission. Although relatively increased Mn2+ contents at the Ca Lattice Position appear to be rather common in evaporitic dolomites the combination of a tabular crystal shape and a preferred input of Mn2+ at the Ca Lattice Position is a remarkable phenomenon. As tabular dolomite crystals so far are exclusively reported from evaporitic diagenetic settings they could be the result of a high Mg/Ca ratio which blocks c-axis orientated growth of dolomite crystal. The occurrence of well ordered dolomite of which the geochemical zoning can be studied in such detail is rare for the earliest, synsedimentary stages of dolomite formation in marine environments, because these early stages commonly consist of not or badly ordered Ca-dolomites. A primary geochemical zoning of such dolomite usually gets lost during stabilisation and transformation to better ordering and stoichiometry.

Detlev K Richter - One of the best experts on this subject based on the ideXlab platform.

  • from tabular to rhombohedral dolomite crystals in zechstein 2 dolostones from scharzfeld sw harz germany a case study with combined cl and ebsd investigations
    Sedimentary Geology, 2010
    Co-Authors: Axel Gillhaus, Detlev K Richter, Thomas Gotte, Rolf D Neuser
    Abstract:

    Abstract Tabular dolomite crystals found within dolomite rhombs have been investigated by cathodoluminescence (CL) microscopy and spectroscopy combined with electron backscatter diffraction (EBSD) for the first time. The dolomites formed in the Upper Permian Stassfurt Carbonate Ca2 at the southern margin of the German/Polish Zechstein Basin. Cathodoluminescence petrography of the dolostone succession revealed that the dolomites developed in four phases. Electron backscatter diffraction analysis reveals tabular crystal growth during the two first generations, while the last two generations are characterized by rhombohedral crystal shapes. The tabular dolomite cement crystals and their microcrystalline equivalents in matrix and components have a stoichiometric comPosition with good to very good Lattice ordering. Manganese and iron contents of the tabular crystals are low and their carbon and oxygen isotope comPosition confirms an early diagenetic dolomite formation under marine-evaporitic conditions from precursor carbonates of Upper Permian age. CL spectroscopy reveals that the tabular dolomite generation 1 has a very high percentage of Mn2+ on the Ca Lattice Position which results in a visually yellowish-green CL emission. Although relatively increased Mn2+ contents at the Ca Lattice Position appear to be rather common in evaporitic dolomites the combination of a tabular crystal shape and a preferred input of Mn2+ at the Ca Lattice Position is a remarkable phenomenon. As tabular dolomite crystals so far are exclusively reported from evaporitic diagenetic settings they could be the result of a high Mg/Ca ratio which blocks c-axis orientated growth of dolomite crystal. The occurrence of well ordered dolomite of which the geochemical zoning can be studied in such detail is rare for the earliest, synsedimentary stages of dolomite formation in marine environments, because these early stages commonly consist of not or badly ordered Ca-dolomites. A primary geochemical zoning of such dolomite usually gets lost during stabilisation and transformation to better ordering and stoichiometry.

  • From tabular to rhombohedral dolomite crystals in Zechstein 2 dolostones from Scharzfeld (SW Harz/Germany): A case study with combined CL and EBSD investigations
    Sedimentary Geology, 2010
    Co-Authors: Axel Gillhaus, Detlev K Richter, Thomas Gotte, Rolf D Neuser
    Abstract:

    Abstract Tabular dolomite crystals found within dolomite rhombs have been investigated by cathodoluminescence (CL) microscopy and spectroscopy combined with electron backscatter diffraction (EBSD) for the first time. The dolomites formed in the Upper Permian Stassfurt Carbonate Ca2 at the southern margin of the German/Polish Zechstein Basin. Cathodoluminescence petrography of the dolostone succession revealed that the dolomites developed in four phases. Electron backscatter diffraction analysis reveals tabular crystal growth during the two first generations, while the last two generations are characterized by rhombohedral crystal shapes. The tabular dolomite cement crystals and their microcrystalline equivalents in matrix and components have a stoichiometric comPosition with good to very good Lattice ordering. Manganese and iron contents of the tabular crystals are low and their carbon and oxygen isotope comPosition confirms an early diagenetic dolomite formation under marine-evaporitic conditions from precursor carbonates of Upper Permian age. CL spectroscopy reveals that the tabular dolomite generation 1 has a very high percentage of Mn2+ on the Ca Lattice Position which results in a visually yellowish-green CL emission. Although relatively increased Mn2+ contents at the Ca Lattice Position appear to be rather common in evaporitic dolomites the combination of a tabular crystal shape and a preferred input of Mn2+ at the Ca Lattice Position is a remarkable phenomenon. As tabular dolomite crystals so far are exclusively reported from evaporitic diagenetic settings they could be the result of a high Mg/Ca ratio which blocks c-axis orientated growth of dolomite crystal. The occurrence of well ordered dolomite of which the geochemical zoning can be studied in such detail is rare for the earliest, synsedimentary stages of dolomite formation in marine environments, because these early stages commonly consist of not or badly ordered Ca-dolomites. A primary geochemical zoning of such dolomite usually gets lost during stabilisation and transformation to better ordering and stoichiometry.

Thomas Gotte - One of the best experts on this subject based on the ideXlab platform.

  • from tabular to rhombohedral dolomite crystals in zechstein 2 dolostones from scharzfeld sw harz germany a case study with combined cl and ebsd investigations
    Sedimentary Geology, 2010
    Co-Authors: Axel Gillhaus, Detlev K Richter, Thomas Gotte, Rolf D Neuser
    Abstract:

    Abstract Tabular dolomite crystals found within dolomite rhombs have been investigated by cathodoluminescence (CL) microscopy and spectroscopy combined with electron backscatter diffraction (EBSD) for the first time. The dolomites formed in the Upper Permian Stassfurt Carbonate Ca2 at the southern margin of the German/Polish Zechstein Basin. Cathodoluminescence petrography of the dolostone succession revealed that the dolomites developed in four phases. Electron backscatter diffraction analysis reveals tabular crystal growth during the two first generations, while the last two generations are characterized by rhombohedral crystal shapes. The tabular dolomite cement crystals and their microcrystalline equivalents in matrix and components have a stoichiometric comPosition with good to very good Lattice ordering. Manganese and iron contents of the tabular crystals are low and their carbon and oxygen isotope comPosition confirms an early diagenetic dolomite formation under marine-evaporitic conditions from precursor carbonates of Upper Permian age. CL spectroscopy reveals that the tabular dolomite generation 1 has a very high percentage of Mn2+ on the Ca Lattice Position which results in a visually yellowish-green CL emission. Although relatively increased Mn2+ contents at the Ca Lattice Position appear to be rather common in evaporitic dolomites the combination of a tabular crystal shape and a preferred input of Mn2+ at the Ca Lattice Position is a remarkable phenomenon. As tabular dolomite crystals so far are exclusively reported from evaporitic diagenetic settings they could be the result of a high Mg/Ca ratio which blocks c-axis orientated growth of dolomite crystal. The occurrence of well ordered dolomite of which the geochemical zoning can be studied in such detail is rare for the earliest, synsedimentary stages of dolomite formation in marine environments, because these early stages commonly consist of not or badly ordered Ca-dolomites. A primary geochemical zoning of such dolomite usually gets lost during stabilisation and transformation to better ordering and stoichiometry.

  • From tabular to rhombohedral dolomite crystals in Zechstein 2 dolostones from Scharzfeld (SW Harz/Germany): A case study with combined CL and EBSD investigations
    Sedimentary Geology, 2010
    Co-Authors: Axel Gillhaus, Detlev K Richter, Thomas Gotte, Rolf D Neuser
    Abstract:

    Abstract Tabular dolomite crystals found within dolomite rhombs have been investigated by cathodoluminescence (CL) microscopy and spectroscopy combined with electron backscatter diffraction (EBSD) for the first time. The dolomites formed in the Upper Permian Stassfurt Carbonate Ca2 at the southern margin of the German/Polish Zechstein Basin. Cathodoluminescence petrography of the dolostone succession revealed that the dolomites developed in four phases. Electron backscatter diffraction analysis reveals tabular crystal growth during the two first generations, while the last two generations are characterized by rhombohedral crystal shapes. The tabular dolomite cement crystals and their microcrystalline equivalents in matrix and components have a stoichiometric comPosition with good to very good Lattice ordering. Manganese and iron contents of the tabular crystals are low and their carbon and oxygen isotope comPosition confirms an early diagenetic dolomite formation under marine-evaporitic conditions from precursor carbonates of Upper Permian age. CL spectroscopy reveals that the tabular dolomite generation 1 has a very high percentage of Mn2+ on the Ca Lattice Position which results in a visually yellowish-green CL emission. Although relatively increased Mn2+ contents at the Ca Lattice Position appear to be rather common in evaporitic dolomites the combination of a tabular crystal shape and a preferred input of Mn2+ at the Ca Lattice Position is a remarkable phenomenon. As tabular dolomite crystals so far are exclusively reported from evaporitic diagenetic settings they could be the result of a high Mg/Ca ratio which blocks c-axis orientated growth of dolomite crystal. The occurrence of well ordered dolomite of which the geochemical zoning can be studied in such detail is rare for the earliest, synsedimentary stages of dolomite formation in marine environments, because these early stages commonly consist of not or badly ordered Ca-dolomites. A primary geochemical zoning of such dolomite usually gets lost during stabilisation and transformation to better ordering and stoichiometry.

Pinwen Zhu - One of the best experts on this subject based on the ideXlab platform.

  • enhanced hardness in tungsten substituted molybdenum diboride solid solutions by local symmetry reduction
    Materials Chemistry and Physics, 2020
    Co-Authors: Feng Zhao, Qiang Tao, Cun You, Xin Wang, Tian Cui, Yang Han, Shushan Dong, Pinwen Zhu
    Abstract:

    Abstract MoB2, with a layered structure, is a potential functional material that is expected to be used as catalysts and conductors. However, the lower hardness limits its application in extreme environment. Solid-solution hardening is a suitable way to enhance hardness and keep structure, but it is complicated in transition metal borides (TMBs) solid solutions. Up to now, uncovering the intrinsic factors of solid-solution hardening is still a challenge. In this work, the structural, electronic and hardness properties of Mo1-xWxB2 (x = 0.01~0.20) is studied to explore the potential factors. It is found that sharp increase in hardness of Mo1-xWxB2 at low W doping level (≤5 at%), and highest Vickers hardness of 26.7 ± 1.2 GPa (applied 0.49 N load) was obtained by Mo0.95W0.05B2. The high hardness reason is ascribed to the Lattice distortions lead to internal stress at the nanoscale, which created local symmetry reduction by affected local electron distribution of B–B bond and the Lattice Position of Mo atoms. Moreover, at higher W doping level, TM-B bond is strengthened by increasing electron transfer from the tungsten atoms to the boron atoms, which resulting in the hardness increasing of Mo1-xWxB2. This provides guidance for designing TMBs solid solutions with better mechanical properties.

  • Enhanced hardness in tungsten–substituted molybdenum diboride solid solutions by local symmetry reduction
    Materials Chemistry and Physics, 2020
    Co-Authors: Feng Zhao, Qiang Tao, Cun You, Han Yang, Dong Shushan, Xin Wang, Tian Cui, Pinwen Zhu
    Abstract:

    Abstract MoB2, with a layered structure, is a potential functional material that is expected to be used as catalysts and conductors. However, the lower hardness limits its application in extreme environment. Solid-solution hardening is a suitable way to enhance hardness and keep structure, but it is complicated in transition metal borides (TMBs) solid solutions. Up to now, uncovering the intrinsic factors of solid-solution hardening is still a challenge. In this work, the structural, electronic and hardness properties of Mo1-xWxB2 (x = 0.01~0.20) is studied to explore the potential factors. It is found that sharp increase in hardness of Mo1-xWxB2 at low W doping level (≤5 at%), and highest Vickers hardness of 26.7 ± 1.2 GPa (applied 0.49 N load) was obtained by Mo0.95W0.05B2. The high hardness reason is ascribed to the Lattice distortions lead to internal stress at the nanoscale, which created local symmetry reduction by affected local electron distribution of B–B bond and the Lattice Position of Mo atoms. Moreover, at higher W doping level, TM-B bond is strengthened by increasing electron transfer from the tungsten atoms to the boron atoms, which resulting in the hardness increasing of Mo1-xWxB2. This provides guidance for designing TMBs solid solutions with better mechanical properties.