Search results for "bulk"
showing 10 items of 286 documents
GdBO3 and YBO3 crystals under compression
2021
High-pressure X-ray diffraction studies on nanocrystals of the GdBO3 and YBO3 rare-earth orthoborates are herein reported up to 17.4(2) and 13.4(2) GPa respectively. The subsequent determination of the room-temperature pressure-volume equations of state is presented and discussed in the context of contemporary publications which contradict the findings of this work. In particular, the isothermal bulk moduli of GdBO3 and YBO3 are found to be 170(13) and 163(13) GPa respectively, almost 50% smaller than recent findings. Our experimental results provide an accurate revision of the high-pressure compressibility behaviour of GdBO3 and YBO3 which is consistent with the known systematics in isomor…
LiCrO2 Under Pressure: In-Situ Structural and Vibrational Studies
2018
The high-pressure behaviour of LiCrO2, a compound isostructural to the battery compound LiCoO2, has been investigated by synchrotron-based angle-dispersive X-ray powder diffraction, Raman spectroscopy, and resistance measurements up to 41, 30, and 10 Gpa, respectively. The stability of the layered structured compound on a triangular lattice with R-3m space group is confirmed in all three measurements up to the highest pressure reached. The dependence of lattice parameters and unit-cell volume with pressure has been determined from the structural refinements of X-ray diffraction patterns that are used to extract the axial compressibilities and bulk modulus by means of Birch&ndash
Crystal behavior of potassium bromate under compression.
2015
We report on high-pressure angle-dispersive X-ray diffraction data up to 15 GPa andab initiototal-energy calculations up to 242 GPa for KBrO3. No phase transition was found below 15 Pa in contrast to previously reported data. Its experimental bulk modulus in the quasi-hydrostatic regime isB0= 18.8 (9) GPa with a bulk modulus pressure derivativeB′0= 8.2 (4). However, according to ourab initiocalculations, KBrO3significantly reduces its rhombohedral distortionviasmall cooperative movements of the atoms and the structure progressively approaches the cubic symmetry, where the KBr subarray would adopt a topology similar to that of the corresponding B2-type bromide. This rearrangement of atoms is…
New polymorph of InVO4: A high-pressure structure with six-coordinated vanadium
2013
A new wolframite-type polymorph of InVO4 is identified under compression near 7 GPa by in situ high-pressure (HP) X-ray diffraction (XRD) and Raman spectroscopic investigations on the stable orthorhombic InVO4. The structural transition is accompanied by a large volume collapse (Delta V/V = -14%) and a drastic increase in bulk modulus (from 69 to 168 GPa). Both techniques also show the existence of a third phase coexisting with the low- and high-pressure phases in a limited pressure range close to the transition pressure. XRD studies revealed a highly anisotropic compression in orthorhombic InVO4. In addition, the compressibility becomes nonlinear in the HP polymorph. The volume collapse in…
Electrochemical incineration of 1,2-dichloroethane: Effect of the electrode material
2008
The electrochemical incineration of 1,2-dichloroethane (EDC) at Pt, Au, boron-doped diamond (BDD), Ebonex, stainless steel, Ti/IrO2–Ta2O5 and PbO2 has been studied in acid media by cyclic voltammetry and bulk electrolysis. It has been shown that the performances of the process dramatically depend on the anodic material. Higher current efficiencies were obtained at BDD. In particular, at proper values of applied current density, it is possible to obtain the almost complete conversion of EDC to CO2 at BDD with current efficiencies higher than 40%.
Some effects of a buried electricity transmission cable on bulk soil.
2007
A case study in NW Italy investigating an underground electric line (1 m depth triple cable at operative voltages 220-380 kV) measured electric fields in the surrounding soil virtually close to zero but magnetic fields (microTs) 20 times the background level. After 6 months, the influence radius around the cable on microbial activity (estimated by soil ATP), organic carbon, and total nitrogen follows exactly the inverse trend of the MF, shifting the biological activity with a lag distance of 5 m from the 220 kV cable.
Simultaneous determination of carrier lifetime and electron density-of-states in P3HT:PCBM organic solar cells under illumination by impedance spectr…
2010
We report new insights into recombination kinetics in poly(3-hexylthiophene):methanofullerene (P3HT:PCBM) bulk heterojunction (BHJ) solar cells, based on simultaneous determination of the density of states (DOS), internal recombination resistance, and carrier lifetime, at different steady states, by impedance spectroscopy. A set of measurements at open circuit under illumination was performed aiming to better understand the limitations to the photovoltage, which in this class of solar cells remains far below the theoretical limit which is the difference between the LUMO level of PCBM and the HOMO of P3HT (∼1.1 eV). Recombination kinetics follows a bimolecular law, being the recombination ti…
Preparation of photocatalysts by chemical methodologies
2021
Abstract The synthesis of photocatalytic materials is an important task for obtaining better results in terms of activity and/or selectivity in photocatalysis. This chapter reports an overview of the main methodologies using physical techniques to obtain bulky, supported powders or films and coatings to be used as heterogeneous photocatalysts. The classical chemical methodologies for the preparation of photocatalytic materials are presented in the previous chapter, so the information presented here complements the aforementioned one. Materials scientists and engineers have made significant progresses in the improvement of methods of synthesis of nanomaterial solids by developing different a…
Study of the factors affecting activated sludge settling in domestic wastewater treatment plants
1992
A study has been made of the influence of the process parameters on the settling characteristics of sludge in domestic wastewater treatment plants. The experiments were conducted at a pilot plant situated at the Wastewater Treatment Plant of Valencia, Spain (1,000,000 inhabitants). The influent to the pilot plant was the same as that of the plant. It was found that F/M ratios in the range of 0.25-0.60 g DBO5/g MLVSS day produce values of SVI representative of good settleability of the sludge. Values of sulphide concentration in the influent above 1.0 mg/l negatively affect the process, causing bulking and floating sludge. High values of fats were found to have no influence on the SVI, but d…
Uptake rates of semipermeable membrane devices (SPMDs) for PCDDs, PCDFs and PCBs in water and sediment.
2000
Uptake rates of several PCDDs, PCDFs and PCBs were measured for semipermeable membrane devices (SPMDs) under controlled conditions in bulk water and sediment. The study was performed at 19 degrees C and 11 degrees C, and water and sediment concentrations were measured during the exposure. Linear uptake rates for specific PCDD/Fs and PCBs in 19 degrees C water varied from 34 to 111 l/m2 day and in 11 degrees C water from 8.8 to 96 l/m2 day for the whole SPMD. Uptake rates at 19 degrees C sediment ranged from 9.0 to 80 mgOC/m2 day and in 11 degrees C sediment, from 3.0 to 31, mgOC/m2 day. Partitioning of the compounds between membrane and lipid was also measured during the linear uptake phase…