Metal Ion Layers Research Articles

Step-Nucleation In Situ Self-Repair to Prepare Rollable Large-Area Ultrathin MOF Membranes.

Ultrathin membranes with ultrahigh permeance and good gas selectivity have the potential to greatly decrease separation process costs, but it requires the practical preparation of large area membranes for implementation. Metal-organic frameworks (MOFs) are very attractive for membrane gas separation applications. However, to date, the largest MOF membrane area reported in the literature is only about 100 cm2 . In the present study, a new step-nucleation in situ self-repair strategy is proposed that enables the preparation of large-area (2400 cm2 ) ultrathin and rollable MOF membranes deposited on an inexpensive flexible polymer membrane support layer for the first time, combining a polyvinyl alcohol (PVA)-metal-ion layer and a pure metal-ion layer. The main role of the pure metal-ion layer is to act as the main nucleation sites for MOF membrane growth, while the PVA-metal-ion layer acts as a slow-release metal-ion source, which supplements MOF crystal nucleation to repair any defects occurring. Membrane modules are necessary components for membrane applications, and spiral-wound modules are among the most common module formats that are widely applied in gas separation. A 4800 cm2 spiral-wound membrane modulewas successfully prepared, demonstrating the practical implementation of large-area MOF membranes.

Role of Crystal Structure on the Ionic Conduction and Electrical Properties of Germanate Compounds A2Cu3Ge4O12 (A = Na, K)

Crystal structure and electrical properties of A2Cu3Ge4O12 (where A = Na, K) have been investigated by neutron diffraction and electrical impedance spectroscopy (EIS). The real and imaginary parts of the impedance, dielectric constant, and electrical modulus have been studied as a function of frequency and temperature. The crystal structures of the compounds K2Cu3Ge4O12 (KCGO) and Na2Cu3Ge4O12 (NCGO) are made of perfect 2D and quasi-2D alkali metal ion layers, respectively. The dc conductivity occurs due to small polaron hopping for both compounds with single activation energy over the entire experimentally available temperature range. The values of activation energies are 0.90(3) and 1.22(6) eV for KCGO and NCGO, respectively, as determined from dc conductivity and relaxation time analysis. The frequency dependent ac conductivity curves for both compounds follow a universal Jonscher’s power law. Soft bond valence sum analysis of neutron diffraction data reveals that the conduction pathways are confined within a plane in KCGO, whereas they form a one-dimensional channel in NCGO. The bottlenecks for ionic conduction and the role of crystal structure on them are discussed. The scaling behavior of electrical modulus indicates that the relaxation process does not change with temperature; however, a sharp decrease in the time constant has been observed. The present comprehensive study facilitates the understanding of the role of crystal structure on the microscopic mechanism of ionic conduction in both battery materials, which would be useful in designing sodium and potassium based ionic conductors. Further, the constant value of activation energy over the kHz frequency range is suitable for potential applications of the studied materials in avalanche beacons and amateur and geophysical sensors.

Metallic ion layers in planetary atmosphere: Boundary conditions and IDP flux

Metallic ion layers in planetary atmosphere: Boundary conditions and IDP flux

Martian Meteoric Mg+: Atmospheric Distribution and Variability From MAVEN/IUVS

AbstractSince the discovery of atmospheric Mg+ on Mars in 2015 by the Mars Atmosphere and Volatile Evolution mission, there have been almost continuous observations of this meteoric ion layer in a variety of seasons, local times, and latitudes. Here, we present the most comprehensive set of observations of the persistent metal ion layer at Mars, constructing the first grand composite maps from pooled medians of subsamples of a metallic ion species. These maps demonstrate that Mg+ appears in almost all conditions when illuminated, with peak density values varying between 100 and 500 cm−3, dependent on season and local time. There exists significant latitudinal variation within a given season, indicating that Mg+ is not simply an inert tracer, but may instead be influenced by the meteoric input distribution and/or atmospheric dynamics and chemistry. Geographic maps of Mg+ density as a function of latitude and longitude indicate the influence of atmospheric tides, and there is no apparent correlation with remnant crustal magnetic fields. This work also presents counter‐intuitive results, such as a reduction of Mg+ ions in the northern hemisphere during Northern Winter in an apparent correlation with dust aerosols.

Aggregation mechanism of natural schwertmannite particles covered with two-component layers of high molecular weight tackifier and trace metal ions

This paper aimed at the aggregation mechanism of natural schwertmannite (SCH) particles covered with layers composed of two different substances, i.e., trace metals (cadmium (Cd), copper (Cu)) and commercial polyacrylamide tackifier (PAM). The mineral applied was taken from the Muskau Arch area (Poland) and characterized. Coating of SCH with Cu, Cd, and PAM was conducted in the systems containing one- or two substances. To estimate the mineral aggregation with and without specific adsorption layers, the stability study was carried out. The obtained results indicated that the accumulation of both trace metal ions and polymer was higher in the mixed adsorption layers. Then, the adsorption efficiency of Cd increased even by 25.10% (pH 5). The highest growth in the PAM adsorption was noted at pH 6, i.e., by 49.73% (in the presence of Cu) and 42.80% (Cd). The aggregation of the SCH particles covered with mixed adsorption layers was stronger than that without adsorbates. Under these conditions, the turbidity of the system was only 57.2 NTU (Nephelometric Turbidity Units), whilst after 60 min, 54.4 NTU. In the simultaneous presence of PAM and trace metal ions, the solid particles formed flocs of considerable size. The polymer formed specific bridges between them and thus facilitate their contact (flocculation). What is more, trace metal ions mediated connection of the particles coated with PAM.

IDP detection in Earth environment: Prediction of plasma capture efficiency and detector response to high-energy particles

Interplanetary dust particles exist everywhere in the space between any two planets. These particles are originated from sources like Asteroid belt, Kuiper belt or comets and they evolve through their orbital paths. Various planets like Mars, Earth or Venus may capture such particles during their inward travel. Flux of dust particles at a given planet is important to understand total inflow of material and also, metal ion layers formed in atmosphere due to ablation. Using past observations around Earth and an existing flux model, a power law model is suggested for incoming particle flux at Earth. Expected particle number density around Earth is presented based on the suggested model. To detect such dust particles, an impact ionization dust detector is proposed for planetary application and it is under development at Physical Research Laboratory. A dust impact on detector target produces charge carriers, which are captured by voltage biased electrodes for further processing. For the dust detector, bias optimization is worthwhile to reduce resources required on board a satellite. In this regard, prediction of plasma capture efficiency is presented here using SIMION software, to get first hand estimate of detector performance. In addition, the detector receives high-energy solar wind particles and Galactic Cosmic Rays in space, along with the dust. Therefore, understanding detector response to high-energy particles is utmost important during normal solar conditions and also during SEP events. Through an extensive simulation using Geant4 software and ACE, GOES as well as SPENVIS datasets, it is found that high-energy particles act as noise for the detector in electron channel only. The dust impact can easily be identified from the background noise using the signal coincidence. The results could be useful to understand dust flux at Earth and also for the detector optimization.

Examining the Wind Shear Theory of Sporadic E With ICON/MIGHTI Winds and COSMIC‐2 Radio Occultation Data

AbstractThe wind shear theory is widely accepted as an explanation for the formation of a sporadic E (Es) layer, but the direct comparison of Es with the local wind shear has been limited due to the lack of neutral wind measurements. This study examines the role of the vertical wind shear for Es, using signal‐to‐noise ratio profiles from COSMIC‐2 radio occultation measurements and concurrent measurements of neutral wind profiles from the Ionospheric Connection Explorer. It is observed that the Es occurrence rate and average S4 index are correlated with the negative vertical shear of the eastward wind, providing observational support for the wind shear theory. Es can be observed even when the vertical wind shear is positive, which is interpreted as metallic ion layers generated at an earlier time.

Temporal Evolution of Three‐Dimensional Structures of Metal Ion Layer Around Japan Simulated by a Midlatitude Ionospheric Model

AbstractA regional numerical ionospheric model with neutral winds, corresponding to the Ground‐to‐topside model of Atmosphere and Ionosphere for Aeronomy model, was used to investigate the temporal evolution of 3‐D structures of metal ion layers (MILs) around Japan. The MILs that appear specifically in the ionospheric E region, called “sporadic E,” display complicated multi‐layer structures and intense density variations. Although the wind shear theory elucidates the basic formation mechanism of MILs, it does not fully explain the physical mechanism of 3‐D MIL structures, especially their sporadic behavior. Herein, we present two simulation cases in which the effect of the monthly mean and day‐to‐day variations of wind on the MILs around Japan was investigated. The temporal evolutions of the complicated MIL structures were classified into the following four phases: (1) Above 110 km, MILs are generally constrained vertically and horizontally at the zonal‐wind shear null. (2) Below 110 km, MILs lag behind the zonal‐wind shear null, and the 3‐D MIL structures are affected not only by the wind shears but also by the magnitude and direction of the horizontal winds. (3) When stagnating metal ions exist below a descending MIL, some metal ions ascend and merge with the descending MIL, thereby increasing its density. (4) MILs stagnate at around 100 km or descend to <100 km depending on the strength of the vertical winds. Our results reveal that Phases (2–4) are crucial for the formation of complicated MIL structures.

On the altitude dependence and role of zonal and meridional wind shears in the generation of E region metal ion layers

Krall et al. (2020) simulated metal ion layers in the E region ionosphere observed by the ISR at Arecibo, by considering vertical ion-motion and convergence driven by zonal and meridional winds. They report that the observed altitude structure is produced if only meridional wind forces are included in the model. Also, layer formation below 110 km, where the ions are very weakly magnetized, is supported mainly by meridional wind shears. We question these finding which contrast with our present knowledge. We show that layer forming in the lower E region is controlled by zonal, rather than meridional, wind shears.

Analysis of the Silica Sol Surface Structure by X-Ray Scattering Method

The structure of the planar surface of colloidal solutions of amorphous 27-nm silica sol particles enriched with heavy K+, Rb+, and Cs+ alkali ions is studied by the methods of reflectometry and diffuse (nonspecular) scattering of synchrotron radiation. For liquid-phase systems, we have used a self-consistent approach that makes it possible to reconstruct from experimental data the electron density profiles perpendicular to the hydrosol surface, as well as the spectra of the height–height correlation function in the plane of the surface without using any a priori information about the near-surface structure. Analysis represented here shows that for high values of pH, alkali cations with a large radius and a surface concentration of (5 ± 1) × 1018 m–2 replace Na+ ions with a smaller radius. This result is in qualitative agreement with the dependence of the Kharkats–Ukstrup single-ion electrostatic free energy on the ion radius and in good quantitative agreement with the results obtained by other authors using the capillary-wave approach. The integrated value of the effective height of interface roughness (3.2 ± 0.5 A) coincides to within the measuring error with the prediction of the capillary-wave theory; however, the experimental spectra of the height-to-height correlation function basically differ from the theoretical spectra in the range of low spatial frequencies ν < 10–3 nm–1. The approximation of the spectra by the sum of two K-correlation distributions indicates a transition from the natural roughness of the compact layer of alkali metal ions to the capillary roughness of the liquid surface in the correlation length range of about 1 μm. In our opinion, the aggregate of available data indicates the dispersion of this layer into 2D clusters (Wigner islands).

Influence of Processing Route and Chemical Composition on Electrochemical Properties of High-Capacity Layered Oxide Cathodes

To obtain high-capacity Li ion batteries; oxide cathodes with layered structure still remain the ones that provide high enough capacities. It is known that electrons and Li+ ions are being extracted simultaneously in the charging process. During high-voltage charging, more ionic/electronic defects formed in layered oxides will be created. Thus, their electrochemical and structural properties are strongly affected by the formation and/or elimination of these defects. Higher defect concentration, like Li vacancies, VLi’, tends to destabilize its crystal structure. As a result, the phase transformation may occur in the cycled cathode. Accordingly, the capacity fading was frequently observed in cycled layered cathode due to the phase-changing process. Moreover, the existing defects in layered oxides are typically determined by the condition of fabrication processes, for instance the dopants and oxygen partial pressure.In this study, two well-known layered oxides with fixed 80% Ni in the transition metal ion layer, namely NMC 811 and LiNi0.8Co0.15Al0.05O2 (NCA), were investigated. Their minor elements/dopants Mn and Al may play an important role on affecting their defect chemistry as well as electrochemical properties. Thus, their electrical/electrochemical/structural properties are examined as a function of the minor dopants, Mn and Al. First, the electrical measurement of NMC 811 and LiNi0.8Co0.15Al0.05O2 are conducted. Assembled cells using above-mentioned cathode and Li anode with desired liquid electrolyte were tested and cycled. SEM and XRD analyses were conducted on assembled and cycled cells. The analysis and results are illustrated based on the chemical characteristics of doping ions and the electronic/ionic defects induced.

On the necessity of using foμEs instead of foEs in estimating the intensity and variability of sporadic E layers

The ordinary wave critical frequency foEs is measured routinely by ionosondes and used widely in estimating the intensity and occurrence of sporadic E (Es) metal ion layers. Recently, however, it was realized that foEs overestimates Es intensities because it corresponds to the sum of both the layer metal ion plasma and the regular E region plasma densities. To account for this, a new parameter, foμEs, was introduced that corresponds to the Es layer metal plasma density only, and a method was proposed for its calculation. In the present work, an ionosonde data set is analyzed to assess the importance of replacing foEs by foμEs in Es studies. To this objective, the diurnal and seasonal variability of sporadic E is re-examined. It turns out that the Es mean diurnal and seasonal variations estimated by means of using foμEs, differ substantially from those based on foEs, implying that the use of foEs leads to biased results and wrong physical inferences. It is therefore urged that foμEs is adopted and used instead of foEs, in future ionosonde sporadic E studies. The same applies for the case of satellite radio occultation (RO) sporadic E investigations as well, where foμEs should be used, instead of foEs, for calibration and validation purposes. All this is equally valid in the case of the blanketing sporadic E frequency fbEs and the corresponding new parameter fbμEs that needs also to be adopted and used.

Modeling the Impact of Metallic Ion Layers on Equatorial Spread With SAMI3/ESF

AbstractThe impact of region metal ion layers on the development of equatorial plasma bubbles is investigated using the SAMI3/ESF model. We find that metal ion layers reduce the growth rate of the generalized Rayleigh‐Taylor instability (GRTI) and act to suppress the development of equatorial plasma bubbles. This is consistent with theoretical expectations and observations and is attributed to the increase in both the Pedersen and Hall conductances. Additionally, inhomogeneities in the region metal ion layer can map into the layer and alter the morphology of equatorial spread (ESF) bubble evolution. Lastly, we find that if EFS bubbles develop in the presence of a metal ion layer, then the electric fields generated by the instability can lift the metal ions into the region. This is consistent with observations of Fe in the region during equatorial spread .

On the Necessity of Using &lt;i&gt;foμEs&lt;/i&gt; Instead of Foes in Estimating&amp;nbsp;The Intensity and Variability of Sporadic E Layers

The ordinary wave critical frequency foEs is measured routinely by ionosondes and used widely in estimating the intensity and occurrence of sporadic E (Es) metal ion layers. Recently, however, it was realized that foEs overestimates Es intensities because it corresponds to the sum of both the layer metal ion plasma and the regular E region plasma densities. To account for this, a new parameter, foμEs , was introduced that corresponds to the Es layer metal plasma density only, and a method was proposed for its calculation. In the present work, an ionosonde data set is analyzed in order to assess the importance of replacing foEs by foμEs in Es studies. To this objective, the diurnal and seasonal variability of sporadic E is re-examined. It turns out that the Es mean diurnal and seasonal variations estimated by means of using foμEs , differ substantially from those based on foEs, implying that the use of foEs leads to biased results and wrong physical inferences. It is therefore urged that foμEs is adopted and used instead of foEs, in future ionosonde sporadic E studies. The same applies for the case of satellite radio occultation (RO) sporadic E investigations as well, where foµEs should be used, instead for foEs, for calibration and validation purposes.

A Stable Anti-Fouling Coating on PVDF Membrane Constructed of Polyphenol Tannic Acid, Polyethyleneimine and Metal Ion.

A hydrophilic and anti-fouling coating layer was constructed on a polyvinylidene fluoride (PVDF) microfiltration membrane by a novel surface modification method. The pristine membrane was firstly coated by (3-chloropropyl) trimethoxysilane/polyethyleneimine and tannic acid. Then, the metal ion was induced on the coating layer to coordinate with tannic acid and polyethyleneimine, forming a more stable and hydrophilic coating on the surface. The membrane’s surface morphology and chemical element analysis showed that the Tannic acid/ polyethyleneimine (TA/PEI) coating layer was denser and had more stability after the addition of metal ions, and this may be due to the coordination bond formed between the TA/PEI coating and metal ions. The results of the water contact angle and pure water flux measurements showed that the hydrophilicity and wettability of the modified membranes were improved obviously after introducing the metal ion layers. The anti-fouling performance and stability of the modified membrane were also characterized by the underwater oil contact angle (OCA), the separation efficiency, and the contact angle variation value for before and after the rinsing experiment. The modified membrane showed obvious stability and antifouling. Moreover, the retention rate of some composite membranes could reach 99.6%.

Electrochemical Generation of Metal Nanostructures Using Self-Assembled Monolayers As Templates

Controlling electrochemical processes by molecular self-assemblies offers interesting perspectives for nanotechnology as precision and flexibility intrinsic to electrochemistry combines favourably with the range of possibilities for chemical, electronic, and structural modification of electrodes by molecular systems. We exploit this combination for metal electrodeposition using a coordination-controlled deposition scheme. Based on the reduction of a two-dimensional (2D) layer of metal ions coordinated to the tail groups of a self-assembled monolayer (SAM) (1-3), it is extended by using the nanoparticles formed initially from the 2D layer as seeds for deposition from the bulk (3D) electrolyte. A number of opportunities for the generation of nanoscale deposits arise from this particular 2D/3D scheme which, depending on conditions, range from isolated nanoparticles to continuous layers on top of the SAM. Furthermore, by choosing different species coordinated to the SAM and present in the bulk electrolyte, bimetallic nanoparticles can be synthesized. Exploring this coordination-controlled deposition scheme towards the generation of ultra-small metal structures, we investigate the combination of Pd and Cu, which is of interest for the generation of both electrocatalytically active PdCu nanoparticles and membranes for hydrogen separation (4). Deposition is accomplished via complexation of Pd2+ ions to a pyridine-terminated thiol SAM on a Au (111) electrode, followed by an electrochemical reduction in an acidic Cu2+-electrolyte. Cyclic voltammetry (CV), chronoamperometry, and X-ray photoelectron spectroscopy (XPS) reveal three phases, Pd nanoparticle formation, seeding of Cu deposition and formation of a Pd/Cu alloy, followed by the deposition of bulk Cu. To shed light on the initial stage of Pd deposition, density functional theory (DFT) calculations were performed. Contrasting other SAM based deposition schemes which rely on defects in the monolayer (5,6), the coordination controlled deposition harnesses a molecular property, thus providing a better control over the deposition process. The generation of nanostructures by templated electrodeposition was investigated using either SAMs patterned by electron beam lithography or patterns of PdCu nanoparticles produced by selective removal with tips of a scanning tunneling or atomic force microscope. Metal layers with an average thickness of less than 3 nm and structures with lateral dimensions ranging from the micrometer to the sub-10 nanometer range can be formed with this technique. References C. Silien, D. Lahaye, M. Caffio, R. Schaub, N. R. Champness and M. Buck, Langmuir, 27, 2567 (2011).T. Baunach, V. Ivanovo, D. M. Kolb, H. G. Boyen, P. Ziemann, M. Büttner and P. Oelhafen, Adv. Mater., 16, 2024 (2004).O. Shekhah, C. Busse, a Bashir, F. Turcu, X. Yin, P. Cyganik, a Birkner, W. Schuhmann and C. Wöll, Phys. Chem. Chem. Phys., 8, 3375 (2006).L. Mattarozzi, S. Cattarin, N. Comisso, R. Gerbasi, P. Guerriero, M. Musiani and E. Verlato, Electrochim. Acta, 230, 365 (2017).Z. She, A. Di Falco, G. Hähner and M. Buck, Appl. Surf. Sci., 373, 51 (2016).Z. She, A. Di Falco, G. Hähner and M. Buck, Beilstein J. Nanotechnol, 3, 101 (2012). Figure 1

Electrochemical Properties of Low Co-Containing Layered Oxide Cathodes Viewing from Structural, Defect and Processing Variations

Layered oxides containing transition metal ions are known to exhibit higher capacities than ones with spinel or olivine structures. However, higher charging capacity means the creation of more ionic/electronic defects in both cation and/or anion sublattices of layered structure. As a result, their structural and electrochemical properties are strongly affected by the formation and/or elimination of these defects. Moreover, the existing defects in layered oxides are typically determined by the condition of fabrication processes, for instance the oxygen partial pressure. The capacity fading observed in layered oxides is typically caused by the phase transformation of cycled layered oxides. In addition, the structural instability of layered oxides may be due to repeated formation/elimination of large amount of defects. Doping of aliovalent ions has been widely used for control of defects through charge compensation mechanism. Thus, the main objective of this work to investigate (i)the structural/electrochemical properties, (ii) charging/discharging/cycling behaviour (ii) effect of aliovalent doping on high Ni/low Co-containing layered oxides. In this study, the electrical/electrochemical/structural properties of layered oxide containing 80% Ni in transition metal layer are investigated. Layered oxides are fabricated using either solid state reaction or co-precipitation techniques. Ni content in is fixed at 80% in the transition metal ion layers in these cathode materials, the variation in electrochemical properties will be caused by the minor elements/dopants such as Mn and Al. First, the electrical measurement of layered oxides are conducted using sintered disc. Assembled cells using above-mentioned cathode and Li anode with desired liquid electrolyte will be tested and cycled. XPS, SEM and XRD analyses will be conducted on as-assembled as well as cycled cells. The analysed results will be illustrated based on the chemical characteristics of doping ions and the accompanying defects created.

Complex dielectric permittivity of metal and polymer modified montmorillonite

Owing to its high surface area and high surface charge density, clay, either contaminated with heavy metal ions or modified with organic additives as barrier materials, is difficult to assess and monitor. Complex dielectric permittivity (κ*) showed promising potential in tackling the above issues. In this study, the complex dielectric permittivity (κ*) of clays modified with a surfactant, four polymers, and four metal ions was measured at frequencies from 0.2-20 GHz. With the addition of polymer and metal ions, increasing frequency caused a slight decrement in real permittivity but a significant decrement in effective permittivity. A modified linearity polynomial equation, which considered the particle conductivity, was developed to fit the relationship between effective conductivity (σeff) and porosity ranging from 0.7 to 1.0. A three-dimensional Cole-Cole plot (κ'-κeff″-w) shows Cole-Cole circle expansion at higher water content. The resonance strength of modified clays was observed to increase with water content, which suggests that the number of water molecules in the diffuse layer of polymer or metal ions saturated clay increased. However, sorbed polymer and metal ions have an insignificant influence on the resonance time τs and stretching exponent 1-α. κ* can provide nondestructive characterization of metal or polymer modified clays.

Synthesis and Structural Characterization of a Pure ZnAl4(OH)12(SO4)·2.6H2O Layered Double Hydroxide.

The phase purity of a series of ZnAl4(OH)12SO4· nH2O layered double hydroxides (ZnAl4-LDH) obtained from a reaction of bayerite (Al(OH)3) with an excess of zinc(II) sulfate under hydrothermal conditions was investigated as a function of the reaction temperature, the duration of the hydrothermal treatment, and the zinc(II) concentration. The product quality, i.e., crystalline impurities, Al impurities, and bulk Zn:Al ratio, were assessed by powder X-ray diffraction (PXRD), 27Al MAS NMR, and elemental analysis. Structural characterization of a stoichiometric ZnAl4-LDH (120 °C, 9 days, and 2.8 M Zn(II)) showed a well-defined structure of the metal ion layer as evidenced by a single, well-defined Zn environment: i.e., no Zn substitution on the Al sites according to Zn k-edge EXAFS and PXRD. Furthermore, nearly all of the 12 different 1H atoms in the -OH groups and 4 27Al resonances could be assigned using 1H,27Al NMR correlation experiments recorded with ultrafast MAS. The interlayer water content is variable on the basis of thermogravimetric analysis and changes in the 1H MAS NMR spectra with temperature. A composition of ZnAl4(OH)12(SO4)·2.6H2O was obtained from a combination of these techniques and confirmed that ZnAl4-LDH is isostructural with the mineral nickelalumite (NiAl4(OH)12SO4·3H2O).

An Improved Ionosonde‐Based Parameter to Assess Sporadic E Layer Intensities: A Simple Idea and an Algorithm

AbstractIn the long era of sporadic E layer (Es) ionosonde research, the ordinary wave critical frequency foEs is used as a measure of Es layer occurrence and intensity. This practice, however, undermines that sporadic E layers are in fact metal ion layers, whereas foEs relates inherently to the sum of both the layer metal and the regular E region plasma densities. This means that foEs acts as an overestimate of Es intensity, a fact that somehow has been overlooked and escaped attention. To deal with this deficiency, an algorithm is introduced which combines the ionosonde‐measured foEs and virtual height h'Es parameters with International Reference Ionosphere model predictions of E region electron densities, to arrive at a new critical frequency which depends on sporadic E metal plasma density only; therefore, it represents an unbiased estimate of Es layer intensity. The extensive use of foEs in numerous sporadic E studies must have introduced errors in various results in relation with the Es variability in the time, frequency, and space domains. It is therefore important that this new parameter, notated as foμEs, is now adopted and used instead of foEs in the evaluation of sporadic E. The same methodology applies also for the sporadic E blanketing critical frequency fbEs, which at times is taken as an alternative estimate of Es intensity; similarly, a new parameter, notated as fbμEs, should be used instead of fbEs.