Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

https://chemistry.beloit.edu/classes/nanotech/ZnO/mattoday10_05_40.pdf

ZnO - nanostructures, defects, and devices

Advanced thermoelectric technology offers a potential for converting waste industrial heat into useful electricity, and an emission-free method for solid state cooling. Worldwide efforts to find materials with thermoelectric figure of merit, zT values significantly above unity, are frequently focused on crystalline semiconductors with low thermal conductivity. Here we report on Cu_(2−x)Se, which reaches a zT of 1.5 at 1,000 K, among the highest values for any bulk materials. Whereas the Se atoms in Cu_(2−x)Se form a rigid face-centred cubic lattice, providing a crystalline pathway for semiconducting electrons (or more precisely holes), the copper ions are highly disordered around the Se sublattice and are superionic with liquid-like mobility. This extraordinary ‘liquid-like’ behaviour of copper ions around a crystalline sublattice of Se in Cu_(2−x)Se results in an intrinsically very low lattice thermal conductivity which enables high zT in this otherwise simple semiconductor. This unusual combination of properties leads to an ideal thermoelectric material. The results indicate a new strategy and direction for high-efficiency thermoelectric materials by exploring systems where there exists a crystalline sublattice for electronic conduction surrounded by liquid-like ions.

Copper ion liquid-like thermoelectrics

High concentrations of defects are introduced into nanoscale ZnO through non-equilibrium processes and resultant blue emissions are comprehensively analyzed, focusing on defect origins and broad controls. Some ZnO nanoparticles exhibit very strong blue emissions, the intensity of which first increase and then decrease with annealing. These visible emissions exhibit strong and interesting excitation dependences: 1) the optimal excitation energy for blue emissions is near the bandgap energy, but the effective excitation can obviously be lower, even 420 nm (2.95 eV < Eg = 3.26 eV); in contrast, green emissions can be excited only by energies larger than the bandgap energy; and, 2) there are several fixed emitting wavelengths at 415, 440, 455 and 488 nm in the blue wave band, which exhibit considerable stability in different excitation and annealing conditions. Mechanisms for blue emissions from ZnO are proposed with interstitial-zinc-related defect levels as initial states. EPR spectra reveal the predominance of interstitial zinc in as-prepared samples, and the evolutions of coexisting interstitial zinc and oxygen vacancies with annealing. Furthermore, good controllability of visible emissions is achieved, including the co-emission of blue and green emissions and peak adjustment from blue to yellow.

/pdf/blue-luminescence-of-zno-nanoparticles-based-on-non-1rinmcderc.pdf

Blue Luminescence of ZnO Nanoparticles Based on Non‐Equilibrium Processes: Defect Origins and Emission Controls

There has been a renaissance of interest in exploring highly efficient thermoelectric materials as a possible route to address the worldwide energy generation, utilization, and management. This review describes the recent advances in designing high-performance bulk thermoelectric materials. We begin with the fundamental stratagem of achieving the greatest thermoelectric figure of merit ZT of a given material by carrier concentration engineering, including Fermi level regulation and optimum carrier density stabilization. We proceed to discuss ways of maximizing ZT at a constant doping level, such as increase of band degeneracy (crystal structure symmetry, band convergence), enhancement of band effective mass (resonant levels, band flattening), improvement of carrier mobility (modulation doping, texturing), and decrease of lattice thermal conductivity (synergistic alloying, second-phase nanostructuring, mesostructuring, and all-length-scale hierarchical architectures). We then highlight the decoupling of th...

Rationally Designing High-Performance Bulk Thermoelectric Materials

Connection between oxygen-ion conductivity of pyrochlore fuel-cell materials and structural change with composition and temperature

Single-crystal neutron diffraction study of the fast-ion conductor β-Ag2S between 186 and 325°C

Single crystal neutron diffraction analysis of the cation distribution in the high-temperature phases α-Cu2−xS, α-Cu2−xSe, and α-Ag2Se

Anion self-diffusion coefficients normal to (1 anti 102) were obtained for single-crystal Al/sub 2/O/sub 3/ in a 1.3 x 10/sup -3/ N/m/sup 2/ (10/sup -5/ torr) vacuum at 1585/sup 0/ to 1840/sup 0/C. Tracer was supplied from an initial 650 to 1300 A Al/sub 2//sup 18/O/sub 3/ layer produced by the oxidation of vapor-deposited Al metal films in an /sup 18/O/sub 2/ atmosphere at 520/sup 0/C. Concentration gradients extended over depths of 3000 to 5000 A and were measured by mass spectrometry of material sputtered from the samples with a beam of Ar/sup +/ ions. Crystals which had not been preannealed to remove surface damage displayed enhanced diffusion. Diffusion coefficients from preannealed crystals may be described by D/sub -0/ = 6.4 x 10/sup 5/ cm/sup 2//s, with an activation energy of 188 +- 7 kcal/mol. The diffusion is interpreted as an extrinsic vacancy mechanism.

Ion‐Probe Measurement of Oxygen Self‐Diffusion in Single‐Crystal Al2O3

In spite of its simple composition, the structure of chalcocite, CU 2 S, has long defied analysis. In high chalcocite the sulfur atoms are in hexagonal close-packing, while three varieties of copper atoms, with four-fold, three-fold, and two-fold coordinations respectively, are in disorder in the interstices.

https://science.sciencemag.org/content/sci/141/3577/276.full.pdf

Bernhardt J. Wuensch

Papers

Connection between oxygen-ion conductivity of pyrochlore fuel-cell materials and structural change with composition and temperature

Single-crystal neutron diffraction study of the fast-ion conductor β-Ag2S between 186 and 325°C

Single crystal neutron diffraction analysis of the cation distribution in the high-temperature phases α-Cu2−xS, α-Cu2−xSe, and α-Ag2Se

Ion‐Probe Measurement of Oxygen Self‐Diffusion in Single‐Crystal Al2O3

Distribution of Atoms in High Chalcocite, Cu2S