2O3 Composites Research Articles

Crystal Surface Engineering Induced Active Hexagonal Co2 P-V2 O3 for Highly Stable Lithium-Sulfur Batteries.

Purposeful control of the highly active crystal planes is an effective strategy to improve the nanocrystalline catalytic activity. Therefore, Co2 P nanocrystals with high exposure of (211) lattice plane loaded at 2D hexagonal V2 O3 nanosheets (H-Co2 P-V2 O3 ) are designed via the control of morphology. After optimization, this H-Co2 P-V2 O3 boosts the redox kinetics of lithium polysulfides (LiPSs) in lithium-sulfur batteries (LSBs), which is due to the increase of the Co-active sites by exposing more (211) lattice planes of Co2 P, and the high adsorption and catalysis characteristic of H-Co2 P-V2 O3 for the conversion of LiPSs into LSBs. In the case of modification separator by H-Co2 P-V2 O3 composite, the battery achieves an outstanding reversibility of 876.9 mAh g-1 over 500 cycles at 1 C, a superior rate property of 611.5 mAh g-1 at 8 C, and a long-term cycling performance with a low attenuation of 0.04% per cycle over 1000 cycles at 4 C for LSBs. Impressively, a remarkable areal capacity of 12.38 mAh cm-2 is retained under the high sulfur loading of 14.5mg cm-2 after 100 cycles. It is believed that the crystal surface engineering provides guidance to further improve the electrochemical performance of the LSB field.

Lead-free KNNS–BNZH-based piezo-active composites with an improved acoustic impedance and related figure of merit

New modeling results on the volume-fraction and aspect-ratio dependences of the acoustic impedance Z*, related figure of merit FE* and other parameters of piezo-active lead-free 1–3-type composites are analysed to show ways for improving Z* and FE*. In these composites, the main component (aligned poled dense ferroelectric ceramic rods) is characterised by the 0.965(K0.45Na0.55)(Nb0.96Sb0.04)O3–0.035Bi0.5Na0.5Zr0.85Hf0.15O3 composition, and the matrix is piezo-passive (either polyethylene or 0–3 corundum ceramic/polyethylene). Changes of Z*∼ (1–10) MRayl, non-monotonic behaviour of FE* and a large anisotropy of piezoelectric coefficients |d33*/d31*|≥ 5 and electromechanical coupling factors |k33*/k31*|≥ 5 are predicted and discussed for a 1–0–3 composite wherein its 0–3 matrix contains components with a large difference of their elastic properties. Results on the acoustic impedance and related parameters show that the studied composites are of value in acoustic transducer, sensor and structural health monitoring applications.

The Use of Hydrogen as a Potential Reductant in the Chromite Smelting Industry

The chromium (Cr) content of stainless steel originates from recycled scrap and/or ferrochrome (FeCr), which is mainly produced by the carbothermic reduction of chromite ore. Ever-increasing pressure on FeCr producers to curtail carbon emissions justifies migration from traditional FeCr production routes. The interaction between hydrogen and chromite only yields water, foregoing the generation of significant volumes of CO-rich off-gas during traditional smelting procedures. For this reason, the use of hydrogen as a chromite reductant is proposed. In addition to thermodynamic modelling, the influence of temperature, time, and particle size on the reduction of chromite by hydrogen was investigated. It was determined that, at the explored reduction parameters, the iron (Fe)-oxides presented in chromite could be metalized and subsequently removed by hot-acid leaching. The Cr-oxide constituency of chromite did not undergo appreciable metalization. However, the removal of Fe from the chromite spinel allowed the formation of eskolaite with the composition of (Cr1.4Al0.6)O3 in the form of an exsolved phase, which may adversely affect the reducibility of chromite. The study includes the limitations of incorporating hydrogen as a reductant into existing FeCr production infrastructure and proposes possible approaches and considerations.

Temperature Dependent Dielectric and Structural Properties of (Ba1-xCax)(Zr0.1Ti0.9)O3, (0.140 ≤ x ≤ 0.160) Ceramics

Ceramic pellets of (Ba1-xCax)(Zr1-yTiy)O3, (x = 0.140 to 0.160, y = 0.9), were prepared via solid- state reaction method followed by double sintering. Dielectric properties (ε, tan δ, and σ) of the prepared compositions were measured, in the temperature range from RT (room temperature) to 450 °C, at various frequencies (12–1000 kHz). The dielectric measurements show a single phase transition, around 100 °C, for the prepared (Ba1-xCax)(Zr1-yTiy)O3 (BCZT) compositions, in the measured temperature range. The structural variation was studied using high temperature X- ray diffraction (HT- XRD) measurements of the compositions with x = 0.150 and 0.155. The HT- XRD results were found consistent with the dielectric measurements, showing structural anomaly at around 100 °C; showing tetragonal phase, between RT and around 100 °C; and cubic phase, above 100 °C, in the measured temperature range.

Synergy of ferroelectric-relaxor transition and multiphase coexistence induced high electrocaloric effect with wide temperature span in Pb0.7Ba0.3ZrO3-based system

In this work, (1-x)Pb0.7Ba0.3ZrO3–xBi(Mg0.5Ti0.5)O3 (PBZ–xBMT) compositions was designed with an integration of ferroelectric–relaxor transition and multiphase coexistence to synergistically optimize electrocaloric effect (ECE) and temperature stability. Rietveld refinements reveal a phase structure change with sequence of R3cH → R3cH + Pm3¯m → Pm3¯m as BMT content increases, whilst relaxation property also increases with downshift in ferroelectric–relaxor transition temperature. Structural evolution is also verified by in-situ Raman spectra and ferroelectric measurements. Interestingly, a large ECE (ΔT ∼ 0.86 K) with a broad temperature span (ΔTspan ∼ 58 K) was successfully obtained in x=0.01 composition, which is believed to be contributed by diffuse phase transition character with multiphase coexistence. This work provides a guideline to exploring ferroelectric materials with high ECE/wide operation span and the reported PBZ–based ceramics with a large ΔT and ΔTspan is a promising candidate in application of solid–state cooling devices.

Magnetically Double-Shelled Layered Double Oxide (LDO)/LDO/γ-Fe2O3 Composite for Highly Efficient Removal of Congo Red and Chromium(VI)

Novel double-shelled core-shell-type magnetic composites MgFexAl-LDO/LDO/γ-Fe2O3 (x = 0, 0.1, and 0.5) were synthesized by a cost-effective two-step coprecipitation method followed by proper calcination. The composites are constructed by two layers of LDO nanosheets (∼80 × 10 nm) which shows vertically oriented relay growth on the surface of spherical γ-Fe2O3. The thickness of LDO shells is ca. 220 ∼ 260 nm, providing a large number of effective adsorption sites and numerous open channels composed of adjacent LDO nanosheets. All the composites show excellent adsorption capacities for Congo Red (CR) and Cr(VI). Especially, the MgAl-LDO/LDO/γ-Fe2O3 exhibits the maximum adsorption capacity (qmax = 123.4 mg g–1) for Cr(VI), which is due to the double-shelled morphology with a large Brunauer–Emmett–Teller area (219 m2 g–1), the electrostatic attraction between the positive LDO shells and Cr(VI) oxyanions, and the adsorption-coupled reduction, with the adsorbed Cr(VI) anion reduced to Cr(III) by hydroxyl groups of the hydrated metal ions and reconstructed into layer double hydroxide layers by the “memory effect”. The MgAl-LDO/LDO/γ-Fe2O3 and MgFe0.1Al-LDO/LDO/γ-Fe2O3 show extraordinary adsorption efficiency for CR with very close qmax values (3980 and 3832 mg g–1, respectively). The former can be attributed to its large SBET and strong LDO shells─CR anion electrostatic interaction, while the latter (99 m2 g–1) can still be ascribed to the complexing function of a small amount of Fe3+ species to CR. The MgAl-LDO/LDO/γ-Fe2O3 composite can be conveniently separated and recovered from the aqueous solution after adsorption by an external magnet. The fourth cycle efficiency of up to 84% implies a promising application prospect.

Manganese Cadmium Sulfide Nanoparticles Solid Solution on Cobalt Acid Nickel Nanoflakes: A Robust Photocatalyst for Hydrogen Evolution.

Photocatalytic water splitting for hydrogen evolution is one of the most promising methods to mitigate environmental and energy-related issues. In this study, manganese cadmium sulfide (Mnx Cd1-x S) solid solution is used to construct a p-n heterostructure with NiCo2 O4 through a hydrothermal method. The Mn0.25 Cd0.75 S/NiCo2 O4 composites are used for photocatalytic hydrogen evolution reaction, and the optimal hydrogen rate with 40 mg of Mn0.25 Cd0.75 S/NiCo2 O4 40 mg (MCS/NCO 40) is 61159 μmol g-1 h-1 , which is about 16.3 times than that of pure Mn0.25 Cd0.75 S. After combining with NiCo2 O4 , the light absorption scale, the separation efficiency of photogenerated carriers, and the reaction kinetics are enhanced. Moreover, the band offset of MCS/NCO composites is calculated by the core level alignment method, demonstrating the formation of a p-n heterostructure. The built-in electric field from the p-n heterostructure drives charge transfer and enhances separation efficiency, which results in improved photocatalytic performance.

Mono, dual and tri-doped TiO2: Sunlight photocatalytic, room temperature ferromagnetic and dielectric constant properties

In this study, the optical, magnetic and electrical properties of nanostructured TiO2 semiconductor have been investigated for multi-functional applications. Herein, different compositions composed of TiO2, Ti0.985Co0.015O2, Ti0.97Co0.015Mn0.015O2, Ti0.97Co0.015Fe0.015O2 and Ti0.97Co0.01Mn0.01Fe0.01O2 were synthesized by coprecipitation method. The XRD and Rietveld refinement analysis confirmed that TiO2, Ti0.985Co0.015O2, Ti0.97Co0.015Mn0.015O2 and Ti0.97Co0.01Mn0.01Fe0.01O2 powders have mixed phases of rutile and anatase TiO2 structure while Ti0.97Co0.015Fe0.015O2 powder has anatase structure. The incorporation of Co, (Co, Mn), (Co, Fe) and (Co, Mn, Fe) ions into TiO2 lattice decreases the band gap energy from 3.13 eV to 3.05, 2.7, 3.08 and 2.88 eV, respectively. Ti0.985Co0.015O2 and Ti0.97Co0.015Fe0.015O2 samples exhibit high sunlight efficiencies of 73% and 72% for Congo red (CR) dye degradation in 80 min, respectively. The dielectric constant and electrical conductivity of TiO2 were enhanced due to insertion of Co2+, Mn2+ and Fe2+/3+ ions. Among all samples, Ti0.97Co0.015Mn0.015O2 composition reveals the highest dielectric constant value of 5004. On the other hand, notable room temperature ferromagnetism with found in Ti0.97Co0.015Fe0.015O2 composition with magnetization value of 0.056 emu/g and coercivity of 86 Oe. The obtained results confirmed that the incorporation of Co2+, Mn2+ and Fe2+/3+ ions into TiO2 enhances the electrical, magnetic and photocatalytic properties.

Phase-Reconfiguration-Induced NiS/NiFe2 O4 Composite for Performance-Enhanced Zinc-Air Batteries.

Constructing composite structures is an essential approach for obtaining multiple functionalities in a single entity. Available synthesis methods of the composites need to be urgently exploited; especially in situ construction. Here, a NiS/NiFe2 O4 composite through a local metal-S coordination at the interface is reported, which is derived from phase reconstruction in the highly defective matrix. X-ray absorption fine structure confirms that long-range order is broken via the local metal-S coordination and, by using electron energy loss spectroscopy, the introduction of NiS/NiFe2 O4 interfaces during the irradiation of plasma energy is identified. Density functional theory (DFT) calculations reveal that in situ phase reconfiguration is crucial for synergistically reducing energetic barriers and accelerating reaction kinetics toward catalyzing the oxygen evolution reaction (OER). As a result; it leads to an overpotential of 230mV @10 mA cm-2 for the OER and a half-wave potential of 0.81 Vfor the oxygen reduction reaction (ORR); as well as an excellent zinc-air battery (ZAB) performance with a power density of 148.5 mW cm-2 . This work provides a new compositing strategy in terms of fast phase reconstruction of bifunctional catalysts.

Effects of the Sn4+ Substitution and the Sintering Additives on the Sintering Behavior and Electrical Properties of PLZT

(Pb, La)(Zr, Ti)O3 (PLZT) with antiferroelectric properties can be applied as a capacitor whose capacitance increases in a high electric field. From this, we obtained a high sintering density at 950 °C by adding low-temperature sintering additives, 8.0 wt% of PbO and 2.5 wt% of ZnO, simultaneously to a (Pb0.88, La0.12)(Zr0.86, Ti0.14)O3 composition. The change in electrical characteristics was confirmed in terms of Sn4+ substitution, resulting in no change in the sintering density by Sn4+ substitution. However, as the amount of Sn4+ substitution increases, the dielectric constant gradually decreases from 1300 to 700, and the grain size decreases from about 4 to 1 µm in terms of microstructure. In the crystal structure analysis, the general formation of a single perovskite structure was confirmed. The results of the hysteresis curve measurement revealed that the breakdown electric field increases from 4 to 9 kV·mm−1 as the amount of Sn4+ substitution gradually increases. However, polarization decreases in the same way as the permittivity trend. The composition exhibits excellent electrical properties when the ratio of Sn4+ is 0.4: a high energy storage density of 3.5 J·cm−3, energy efficiency of 80%, and breakdown electric field of about 8.5 kV·mm−1.

Enhanced Photo-Fenton Activity of SnO2/α-Fe2O3 Composites Prepared by a Two-Step Solvothermal Method

The x-SnO2/α-Fe2O3 (x = 0.04, 0.07, and 0.1) heterogeneous composites were successfully prepared via a two-step solvothermal method. These composites were systematically characterized by the X-ray diffraction technique, field emission scanning electron microscopy, an energy dispersive spectrometer, X-ray photoelectron spectroscopy and a UV–visible spectrometer. It was found that SnO2 nanoparticles were uniformly decorated on the surface of α-Fe2O3 particles in these heterogeneous composites. A comparative study of methylene blue (MB) photodegradation by α-Fe2O3 and x-SnO2/α-Fe2O3 composites was carried out. All x-SnO2/α-Fe2O3 composites showed higher MB photodegradation efficiency than α-Fe2O3. When x = 0.07, the MB photodegradation efficiency can reach 97% in 60 min. Meanwhile, the first-order kinetic studies demonstrated that the optimal rate constant of 0.07-SnO2/α-Fe2O3 composite was 0.0537 min−1, while that of pure α-Fe2O3 was only 0.0191 min−1. The catalytic mechanism of MB photodegradation by SnO2/α-Fe2O3 was examined. The SnO2 can act as a sink and help the effective transfer of photo-generated electrons for decomposing hydrogen peroxide (H2O2) into active radicals. This work can provide a new insight into the catalytic mechanism of the photo-Fenton process.

Deformation and fracture of Nb/α-Al2O3 composites in compression and bending studied by optical methods

AbstractThe fracture behavior of Nb/α-Al2O3composites was investigated both in compression tests and bending tests using an optical full-field method for the observation of strain fields on the metal surfaces. Joints of polycrystalline materials were prepared by high-vacuum diffusion bonding. The building up of the strain near the interface during the tests, finally leading to the fracture, was studied by examining the strain and displacement fields of the whole metal layer. In compression tests, two types of fracture, fracture of alumina and fracture of interfaces, were detected by cross-examination of the stress –strain curve and the strain maps. The fracture of alumina in compression tests was influenced by the Nb layer thickness and can be rationalized by an extension of Cottrell’s model. For four-point bending tests, the results of the strain maps, determined experimentally by means of the optical method, confirmed the strain maps resulting from finite element simulations.

Inhomogeneous electric field-induced structural changes in soft lead zirconate titanate ferroelectric ceramics

Under the application of an external voltage, high electric field concentrations can develop around the interdigitated electrode edges inside multilayer ceramic actuators (MLCAs). The spatial distribution of the local electrical field can create local inhomogeneity in the electromechanical response. To investigate the complex field inhomogeneity in MLCAs, partially electroded Nb-doped PbZrxTi1-xO3 samples were investigated via synchrotron-based high-energy X-ray diffraction (XRD) as a function of applied electric field. These in situ experiments allowed us to probe the structural changes as a function of position relative to the electrode edge and calculate the local degree of domain alignment, from which the local electric field directions were inferred. The domain switching behavior, both in amplitude and orientation, was found to be spatially dependent across the inactive regions in partially electroded samples. Specifically, the degree of domain alignment and field-induced phase transitions are amplified near the electrode edge. The orientation-dependent phase transitions are also amplified for the tetragonal composition near the morphotropic phase boundary (MPB), i.e., the Nb-doped PbZr0.53Ti0.47O3 composition. Finite element analysis (FEA) shows spatially-dependent, inhomogeneous electric field distributions in the partial-electrode samples, which closely match the experimentally inferred local electric field directions from XRD. The correlation of FEA and experimental data from XRD corroborates that the ferroelectric domain orientation distributions are being directed, primarily, in the direction of the electric field.

Piezoelectric enhancement and vacancy defect reduction of lead-free Bi0.5Na0.5TiO3-based thin films

To explore new lead-free piezoelectric materials that is both environmentally friendly and healthy to provide the possibility for material selection for microelectromechanical systems. Lead-free piezoelectric (1-x)(0.8Bi0.5Na0.5TiO3-0.2Bi0.5K0.5TiO3)-xBi(Ni0.5Zr0.5)O3 thin films (abbreviated as BNT-BKT-xBNZ) (x=0.00, 0.01, 0.02, 0.03, 0.04) were prepared on Pt(111)/Ti/SiO2/Si substrates by a sol-gel method. Impacts of Bi(Ni0.5Zr0.5)O3 content on the microstructure, dielectric, ferroelectric, and piezoelectric properties were also investigated detailedly. It found that the Bi(Ni0.5Zr0.5)O3 composition had a great influence on the increase of relaxor and the decrease of the oxygen vacancies, which is influential to the promotion of thin-film properties. Thin-film of BNT-BKT-0.02BNZ showed the optimum electrical properties with the polarization of 40.27 μC/cm2, dielectric constants of 477 and effective inverse piezoelectric coefficient reach up to 125.9 p.m./V. Results revealed that the BNT-BKT thin films with 0.02 mol% Bi(Ni0.5Zr0.5)O3-doped are a kind of lead-free piezoelectric materials with superior manifestations with a great development prospect for applications.

Colossal dielectric constant, electric modulus and electrical conductivity of nanocrystalline SnO2: Role of Zr/Mn, Fe or Co dopants

New dielectric compositions composed of SnO2, Sn0.97Zr0.03O2, Sn0.95Zr0.03Mn0.02O2, Sn0.95Zr0.03Fe0.02O2 and Sn0.95Zr0.03Co0.02O2 nanoparticles were synthesized via coprecipitation method. Single phase of SnO2 tetragonal rutile structure was detected in the XRD patterns and the changes of the lattice parameters suggest the substitution of Sn4+ sites by Zr4+, Mn2+, Fe2+ or Co2+ ions. The TEM images show the formation of nano-sized particle of clear crystalline facets within 15–25 ​nm and the HR-TEM image displays identical fringes with lattice spacing close to 0.32 ​nm which can be assigned to (110) crystallographic plane of SnO2 phase. The EDX pattern of Sn0.95Zr0.03Co0.02O2 sample revealed the existence of Sn, O, Zr and Co elements without any other impurities elements. Nanocrystalline SnO2, Sn0.97Zr0.03O2, Sn0.95Zr0.03Mn0.02O2, Sn0.95Zr0.03Fe0.02O2 and Sn0.95Zr0.03Co0.02O2 compositions exhibit band gap energies of 3.4 ​eV, 3.42 ​eV, 3.4 ​eV, 3.45 ​eV and 3.42 ​eV. Undoped SnO2 exhibits a high dielectric constant value of 4014 ​at 42 ​Hz. Interestingly, the Zr monodoping and Zr based Mn, Fe or Co codoping have the ability to increase the dielectric constant of SnO2 by nearly two, three or four-fold to reach to 14321 for Sn0.95Zr0.03Fe0.02O2. The dielectric properties were explained by means of electric modulus formalism. The electrical conductivity of the synthesized powders exhibited semiconducting behavior with temperature. The electrical conductivity of pure, Zr-monodoped and Zr/Mn, Fe or Co codoped SnO2 was increased with increasing the frequency due to the charge-hopping mechanism.

Synthesis, structural and morphological analysis of carbon nanotube doped α-Fe2O3 hybrid composite prepared by solution method

Composites of carbon nanotubes (CNT) with magnetic iron oxide nanoparticles are promising materials with high performance for energy conversion and storage uses. In this regard, herein we present a convenient and cost-effective facile solution method to deposit crystalline hematite (α-Fe2O3) with CNT. The 5 wt% CNT/α-Fe2O3 composite has been successfully fabricated. The effect of 5 wt% CNT/α-Fe2O3 with hematite, the surface morphologies, structure, and chemical compositions of the samples has been studied and discussed in detail.

A novel Z-scheme Bi-Bi2O3/KTa0.5Nb0.5O3 heterojunction for efficient photocatalytic conversion of N2 to NH3

A novel Z-scheme photocatalyst Bi-Bi2O3/KTa0.5Nb0.5O3 (KTN) composite was prepared by a simple solvothermal method.

Lead-based antiferroelectrics revisited for high energy density capacitors and large strain actuators

Lead zirconate stannate titanate (PZST) ceramics with the generic composition of Pb1-0.5xNbx[(ZrySn1-y)1-zTiz]1-xO3 with x representing Nb content (x = 0 or 0.02), y representing Zr:Sn ratio (y = 0.57 or 0.60), and z representing Ti content (z = 0.06 or 0.08), and lead lanthanum zirconate titanate (PLZT) ceramics with the general composition of Pb1-xLax(ZryTi1−y)1−x/4O3 with x = 0.050 − 0.120 were synthesized using solid state reaction method and sintering. The energy density and field induced strain behavior of these compositions were investigated for capacitor and actuator applications, respectively. The focus of the study was to evaluate and discuss the change in the polar state of these ceramics from normal ferroelectric to antiferroelectric to relaxor antiferroelectric to linear dielectric with compositional modification. The highest releasable energy density (1.053 J/cm3) was obtained from the antiferroelectric Pb[(Zr0.60Sn0.40)0.94Ti0.06]O3 composition among the PZST compositions that were investigated, but the efficiencies were generally low (max. 60%) due to the large hysteresis that was observed in these compositions. The highest field induced strain level of 0.26% was also measured in the same composition. In the case of PLZT compositions, the highest releasable energy density values (0.313 J/cm3) with much higher efficiencies (76%) and highest field induced strain levels (0.23%) were obtained from the PLZT compositions with relaxor antiferroelectric character.

Towards a holistic sulfate-water-O2 triple oxygen isotope systematics

Triple oxygen isotope (∆17O with δ18O) signals of H2O and O2 found in sulfate of oxidative weathering origin offer promising constraints on modern and ancient weathering, hydrology, atmospheric gas concentrations, and bioproductivity. However, interpretations of the sulfate-water-O2 system rely on assuming fixed oxygen-isotope fractionations between sulfate and water, which, contrastingly, are shown to vary widely in sign and amplitude. Instead, here we anchor sulfate-water-O2 triple oxygen isotope systematics on the homogeneous composition of atmospheric O2 with empirical constraints and modeling. Our resulting framework does not require a priori assumptions of the O2- versus H2O‑oxygen ratio in sulfate and accounts for the signals of mass-dependent and mass-independent fractionation in the ∆17O and δ18O of sulfate's O2‑oxygen source. Within this framework, new ∆17O measurements of sulfate constrain ~2.3 Ga Paleoproterozoic gross primary productivity to between 6 and 160 times present-day levels, with important implications for the biological carbon cycle response to high CO2 concentrations prevalent on the early Earth.

Prenormative verification and validation of a protocol for measuring magnetite–maghemite ratios in magnetic nanoparticles

An important step in establishing any new metrological method is a prenormative interlaboratory study, designed to verify and validate the method against its stated aims. Here, the 57Fe Mössbauer spectrometric ‘centre of gravity’ (COG) method was tested as a means of quantifying the magnetite/maghemite (Fe3O4/γ-Fe2O3) composition ratio in biphasic magnetic nanoparticles. The study involved seven laboratories across Europe and North and South America, and six samples—a verification set of three microcrystalline mixtures of known composition, and a validation set of three nanoparticle samples of unknown composition. The spectra were analysed by each participant using in-house fitting packages, and ex post facto by a single operator using an independent package. Repeatability analysis was performed using Mandel’s h statistic and modified Youden plots. It is shown that almost all (83/84) of the Mandel h statistic values fall within the 0.5% significance level, with the one exception being borderline. Youden-based pairwise analysis indicates the dominance of random uncertainties; and in almost all cases the data analysis phase is only a minor contributor to the overall measurement uncertainty. It is concluded that the COG method is a robust and promising candidate for its intended purpose.