Cation Radius Research Articles

Size disorder: A descriptor for predicting the single- or dual-phase formation in multi-component rare earth zirconates

Eighteen different 5-component equimolar rare earth zirconates were successfully synthesized by solid state reaction method. Among them, 5 of them exhibit a high-entropy fluorite structure, 8 have a high-entropy pyrochlore structure, and the remaining 5 have dual-phase structures of both pyrochlore and fluorite. For high-entropy rare earth zirconates with single-phase structure, the lattice parameter is almost linearly correlated with the average cation radius ratio. In combination with a large number of previous reports, a summary is made to study the synergistic effects of the average cation radius ratio, configuration entropy and size disorder on the single-phase formation ability of multi-component rare earth zirconates. The conclusion verifies that the size disorder of about 5% is the boundary for the multi-component rare earth zirconates to form a single-phase or dual-phase region, while the average cation radius ratio of 1.467 is the demarcation between a pyrochlore and a defective fluorite structure in the single-phase zone, and the configuration entropy had less effect. Excessive size disorder leads to the enrichment or barrenness of certain components, which is the main reason for the formation of dual phase ceramics. • 18 Different equimolar 5-component rare earth zirconates have been prepared. • The size disorder ( δ *) can predict the single-phase formation ability of zirconates. • δ * = 5% is the boundary between the single- and dual-phase rare earth zirconates. • The single-phase forming ability of rare-earth zirconates is independent of entropy.

Investigation of the protective capabilities of glass from laser sounding depending on its elemental composition

One of the most vulnerable issues in the technical protection of information is to obtain data via leakage through the opto-electronic channel.
 In this paper, studies of the protective capabilities of glass from laser sounding depending on its elemental composition were carried out using such indicators as the coefficients of reflection and absorption of the laser beam by the window glass.
 As a result of the work, an experimental installation based on a continuous solid-state laser was assembled.
 The study of the elemental composition of window glass, which is produced by modern industry, X-ray fluorescence method and the study of the coefficients of reflection and absorption of glass samples in the experimental setup showed that the studied window glass chemically belongs to quartz (silicate).
 All chemical elements involved in its formation can be divided into 3 groups: glass-forming, transitional, modifiers, which affects the optical properties of the studied glasses, as the elements used have different not only qualitative but also quantitative parameters.
 Absorption increases if the number of chemical elements that exhibit amphoteric and non-metallic properties and have (-charge) decreases, and increases if the number of chemical elements in the glass that exhibit the most alkaline, alkaline earth properties and in which the radius of cations (+ions) increases.
 Systematization of the elemental and quantitative composition of the studied window glass in accordance with the periods and groups of the periodic table of chemical elements, enabled the relationship between the electronic structure of chemical elements and the protective properties of glass

Mn ions‐activated Gd3(Al,Ga)5O12 garnet solid‐solution ceramics: Cation substitution for dual wavelength red‐emission

AbstractRed‐emitting color‐convertors have attracted considerable attention for promising applications in solid‐state lighting (SSL) to improve color rendition. However, the current nitride and fluoride phosphor powders have encountered several challenges, such as high cost, narrow emission bands, and insufficient stability during operation, which limit the development of high‐power full‐spectrum SSL. In this study, thermally robust Gd3(Al,Ga)5O12:Mn (GAGG:Mn) solid‐solution ceramics (SSCs) with dual wavelength red‐emission bands were prepared via an oxygen solid‐state sintering reaction. The doped Mn ions occupied octahedral Al3+ and Ga3+ sites to generate Mn4+ luminescent centers with pronounced deep‐red emissions peaking at 698 nm (2E → 4A2), and Mn2+ luminescent centers with broad red emissions at 628 nm (4T1 → 6A1). Because the cationic radius matching effect induced the regulation of valence state of Mn, the photoluminescence of the GAGG:Mn SSCs can be tailored by the substitution of Al3+ with Ga3+. Moreover, the Mn3+ also existed in the GAGG lattice host, and their concentration decreased with increasing Ga3+ contents owing to the mismatch of ionic radius between Mn3+ and Ga3+ ions. With the optimization of Al/Ga ratio and concentration of Mn ions, a broad emission band ranging from 550 to 800 nm (bandwidth = 250 nm) was achieved from Gd3Al3Ga2O12:0.3%Mn SSCs upon 465‐nm excitation. Moreover, the GAGG:Mn SSC has over 17‐fold enhanced thermal conductivity compared with the corresponding phosphor powder. This paper opens a door of regulating the valence state of luminescence centers with cation substitution and the application of oxide red‐emitting color‐convertors.

Experimentally and Theoretically Revealing the Co-Doping Effects of Ce-Sr in Gd2Zr2O7.

To safely dispose radioactive waste (including, e.g., thorium and radiostrontium), Ce4+ and Sr2+ were chosen as simulated surrogates of α and β waste and were introduced into the Gd3+ site in Gd2Zr2O7 to maintain the average cationic radius and to compensate for charge. A series of Gd2-xSrx/2Cex/2Zr2O7 (0.00 ≤ x ≤ 0.25) compounds were examined by experimental and theoretical calculations to investigate the co-doping effects of α and β waste in a Gd2Zr2O7-based matrix. The effects of Ce4+ and Sr2+ content on the phase, unit cell parameters, active modes, mechanical property, and microstructure were studied systematically. Moreover, the limit of incorporation of Ce4+ and Sr2+ in Gd2Zr2O7 pyrochlore and the lattice parameters were also calculated through virtual crystal approximation theory, and the results were found to well agree with experimental results.

Trace element partitioning in zoned clinopyroxene as a proxy for undercooling: Experimental constraints from trachybasaltic magmas

Sector-zoned clinopyroxene records kinetic effects imposed by variable degrees of magma undercooling, ΔT, and can be utilised to track the dynamics of magmatic systems. The partitioning of trace elements into sectors grown in different crystallographic orientations can be used as a proxy for ΔT. However, an experimental assessment of the relationship between trace element zoning and ΔT has been lacking to date. Here we present trace element data from a series of undercooling crystallisation experiments on a primitive trachybasalt from Mt. Etna (Italy), at conditions of crustal storage (400 MPa, NNO + 2), and ΔT ranging from 23 to 173 °C. Changes in ΔT were modulated by varying both resting and liquidus temperatures, the latter via the melt-H2O content of the experiments. The resting temperature was retained for 24 h to ensure the attainment of near-equilibrium conditions.High-resolution elemental mapping reveals the distribution of trace elements in individual clinopyroxene zones. Increasing ΔT drives a shift from polyhedral morphologies with Al-rich prism and Al-poor hourglass sectors (ΔT = 23–25 °C), to skeletal (ΔT = 75–123 °C) and dendritic (ΔT = 132–173 °C) crystals with Al-rich skeletons and Al-poor overgrowths. Aluminium-rich zones have higher concentrations of rare earth elements (REE) and high field strength elements (HFSE) than Al-poor zones across all investigated ΔT conditions, and overall, Al, REE and HFSE contents increase with ΔT. This indicates that tetrahedral aluminium (TAl) and associated charge-balancing mechanisms govern the incorporation of REE and HFSE within clinopyroxene. Lattice strain parameters for REE in the M2 site indicate the incorporation of light relative to heavy REE in clinopyroxene is controlled by competing effects between the strain-free partition coefficient, D0, and the optimum cation radius, r0. Critically, the middle and heavy REE switch from incompatible to compatible with increasing ΔT. Used to model fractional crystallisation, our data demonstrate that fractionation of clinopyroxene at low ΔT controls pre-eruptive melt evolution. Importantly, this indicates crystallisation of clinopyroxene in the deep portions of Mt. Etna’s plumbing system is not rapid and is unlikely to result in the early formation of dendrites.We develop a parameterisation of ΔT based on REE partitioning between experimental clinopyroxene and coexisting melt, which can be applied to sector-zoned augite crystallising from mafic alkaline magmas, to reconstruct dynamic processes and thermal pathways during magma transport and storage. Applied to sector-zoned clinopyroxene microphenocrysts and groundmass microcrysts from the 1974 eccentric eruption at Mt. Etna, our parameterisation tracks an increase in ΔT with magma ascent and eruption, following recharge of Cr-rich mafic magma at depth. Sector-zoned clinopyroxene can track ΔT variations leading to volcanism at Mt. Etna and could be applied to quantify magma dynamics in other active volcanoes.

Lattice disorder effect on the structural, ferroelectric and electrocaloric properties of (Ba, Sr, Ca)TiO3 ceramics

We report the effect of A-site disorder σ2 on the structural, dielectric, ferroelectric (FE) and electrocaloric (EC) properties of lead-free Ba1-x-ySrxCayTiO3 (0.025 ≤ x ≤ 0.3, 0.275 ≤ y ≤ 0.113) perovskites. We have synthesized a series of samples with the same A-site cationic mean radius but different A-site ionic radii variance (i.e., A-site disorder) σ2. The tetragonal distortion and FE Curie temperature TC are found to decrease with decreasing A-site disorder σ2. The temperature of the maximum EC effect decreases from ~120–27 °C with decreasing disorder σ2. The highest adiabatic temperature change ΔT obtained using both the direct and indirect methods reaches ~0.8 K for the sample with optimized A-site disorder σ2. Our results suggest that, in addition to the lattice distortion, the lattice disorder might be a new and effective parameter for promoting the EC effect.

Metal-supported cathodically activated graphite via self-reduction as electrocatalysts for efficient hydrogen evolution reaction

Surface modification is a promising approach to modulate the electrocatalyst properties for their further use in energy storage and conversion. In this work, electrochemical-based approach was proposed to generate metallic particles-supported graphite rod (GR). The approach is based on the cathodic activation of GR in the presence of alkali metal salts in dry organic solvent. The activated GR possess a high reducing power that was successfully employed to spontaneously reduce metallic salts in aqueous media. The surface analyses confirm the formation of metallic nanoparticles supported GR. Interestingly, the metallic nanoparticles were found to be generated onto and intercalated into the GR. Next, the generated materials were used as electrocatalyst to drive the hydrogen evolution reaction. Our results demonstrate that the electrocatalytic performances depend on various parameters including the radius of the alkali metal cation and the injected charge during the electrochemical activation. The as-prepared Pt/Li-GR exhibits the best electrochemical activity and stability toward the hydrogen evolution reaction. The necessary overpotential value to reach a current density of 10 mA cm−2 is 40 mV for the Pt/Li-GR, and almost negligible overpotential change is observed during the stability tests. In addition, the proposed approach was successfully used to generate Pd/Li-GR catalyst. More impressively, the latter displays higher HER performances when compared to other reported Pd-based catalysts and comparable performance with commercial Pt/C catalyst.

Study on the microcosmic superlubricity mechanism of PVPA affected by metal cations

Hydrophilic polymer coatings on artificial implants generate excellent tribological properties. The friction properties of polymer coatings are affected by salt ion factors. Herein, the atomic force microscopy (AFM) was used to show that the superlubricity was achieved between poly(vinylphosphonic acid) (PVPA)-modified Ti6Al4V and polystyrene (PS) microsphere probe lubricated with monovalent salt solutions (LiCl, NaCl, KCl, and CsCl). Considering that adhesion is an important cause of friction changes, the AFM was further utilized to obtain adhesion between friction pairs in different salt solutions. The results indicated that the larger the cation radius in the lubricant, the smaller the adhesion, and the lower the friction coefficient of the PVPA coating. The electrostatic interaction between the PVPA and one-valence cations in lubricants was analyzed by the molecular dynamics (MD) simulation as it was found to be the main influencing factor of the adhesion. Combined analysis results of friction and adhesion indicated that by adjusting the size of cation radius in lubricant, the adhesion between the tribo-pairs can be changed, and eventually the magnitude of friction can be affected. This study opens up a new avenue for analyzing the friction characteristics of hydrophilic polymer coatings from the perspective of intermolecular forces.

Influence of rare-earth doping on the structural and magnetic properties of orthoferrite La0.50R0.50FeO3 ceramics obtained under high pressure

Studies on the impact of co-doping on the structural, magnetic, and magnetocaloric properties of LaFeO3 orthoferrite-based compounds with partial isovalent substitution of La3+ by rare-earth (R) ions have been carried out. Their functional properties have been experimentally and theoretically investigated by X-ray diffraction analysis, differential scanning calorimetry, and magnetic methods as well as a semiempirical approach. The La0.50R0.50FeO3 (R = Nd, Eu, Gd, Dy, Er) ceramics have been taken as a basis and prepared by a solid-state reaction method under cold-pressing at high pressure (P = 4 GPa). The temperature dependences of the magnetization and magnetocaloric characteristics of the La0.50R0.50FeO3 orthoferrites for the whole series of substitutions from R = Ce to Lu have been calculated within the framework of the semiempirical model, assuming linearity of its parameters depending on the R cation radius. The magnetic entropy change ΔSM, relative cooling power RCP, and specific heat capacity ΔCP,H have thereby been obtained. It has been shown that the La0.50Ce0.50FeO3 composition has the highest magnetocaloric parameters with the lowest Néel temperature TN. As the R cation radius decreases, the chemical pressure increases, leading to a decrease in the magnetocaloric characteristics and an increase in TN. This is due to both a size effect of the crystallites and structural distortions. The obtained results show the potential practical applications of orthoferrite-based materials with controlled magnetocaloric effect and phase transition temperature.

Persona of Transition Metal Ions in Solids: A Statistical Learning on Local Structures of Transition Metal Oxides.

The local structure of a transition metal (TM) ion is a function of cation elements and valence states. More than that, in this work, by employing a trove of first‐principles data of TM oxides, the local structures of TM cations are statistically analyzed to extract detailed information about cation site preference, bond length, site structural distortion, and cation magnetization. It is found that cation radius alone poorly describes the local structure of a transition metal oxide, while the statistics of coordination number as well as the TM—O bond length distribution, especially that of the 3d TMs, can provide comprehensive knowledge for understanding the behavior of TM elements. Based on these statistics, the interplay of site distortion due to the Jahn–Teller effect, cation site similarity, and a new set of ionic radii are all obtained to chart the “persona” of transition metal ions in solids.

High temperature corrosion behavior and the inhibition of apatite formation evolving from corrosion of (Y1−xYbx)2SiO5 in water vapor environment

Environmental barrier coatings (EBCs) are usually coated on SiC ceramic or ceramic matrix composites (CMCs), in order to prevent the attack from corrosive media like water vapor and molten oxides. Solid-solutionizing strategy containing high-entropy engineering is considered as an effective way to mediate corrosion resistances of rare-earth silicates, which are promising candidates for the topcoats of EBCs. In this work, high-temperature corrosion behaviors of hot-pressed (Y1−xYbx)2SiO5 ceramics have been investigated in a 50 %H2O–50 %O2 environment at temperatures of 1573/1673/1773 K for 100 h. The main corrosion product of Y2SiO5 is apatite phase, whose formation can be distinctly inhibited by introducing Yb. Consequently, introducing Yb avoids the tensile stress and cracks effectively, which are induced by the volume reduction due to the phase transition to apatite at elevated temperatures. The inhibition of apatite formation by introducing Yb is attributed to the relatively lower volatilization pressure of Yb2O3 than Y2O3 and the smaller cationic radius of Yb3+ than Y3+. Meanwhile, the composition deviations between grain boundary and grain surface results in the grain surface corrosion and ridge-like corrosion characteristics.

Effect of alumina content on the crystal structure, lattice thermal expansion and thermal conductivity of aluminium-rich spinel solid solutions

Magnesium alumina spinel solid solutions with different chemical compositions were synthesized and their crystal structures were refined using the Rietveld method based on synchrotron radiation X-ray diffraction (XRD). A linear relationship between the lattice parameters a0 and x in Mg1-xAl2+2/3x□1/3xO4 was established, the thermal stability and lattice thermal expansion of the solid solutions by in-situ high temperature XRD were investigated. Alumina was eliminated from the high-solubility alumina-rich spinel solid solution to form corundum and a lower-solubility alumina-rich spinel solid solution. The relationship between a0 and temperature is expressed by a quadratic polynomial. The thermal conductivity of Mg1-xAl2+2/3x□1/3xO4 decreased almost linearly with an increase in x, which is attributed to the stronger point-defect scattering effect induced by the difference in atomic mass and cation radii and the increase in cation vacancies as alumina dissolves in spinel.

Effects of the Layer Charge Location and Interlayer Cation on Rectorite Swelling Properties: Comparison between Molecular Dynamics Simulations and Experiments

Understanding the swelling properties of clay minerals is of great significance to environmental science and engineering applications, including environmental remediation, oil and gas wellbore collapse, geological disasters, and commercial additives. The vast majority of experimental and molecular simulation studies have mainly focused on pure clays. However, 70% of clays are mixed-layer clays (MLCs), and the most frequent MLCs is illite-montmorillonite (I-MMT). In this research, grand canonical Monte Carlo and molecular dynamics simulations were used to study the effects of the layer charge location (tetrahedral and octahedral substitution), interlayer cation type (Na+, Cs+, and Ca2+), and water contents on the swelling and hydration properties of rectorite (R1 type I-MMT) and compared with the experimentally measured basal spacing by water vapor adsorption and X-ray diffraction. It turned out that the free swelling ratio was positively correlated with water contents. The order of the three cations’ free expansion rate was Na+, Ca2+, and Cs+. The swelling process of rectorite (REC) was revealed from porosity changing with water contents. The surface of tetrahedral substitution (T-substitution) clay was more likely to bind to interlayer cations to form an inner-sphere surface complex (ISSC), the number of fully hydrated cations of the T-substitution clay was less than that of octahedral substitution (O-substitution), and REC was more swelling in O-substitution, which was supported by the basal spacing, atomic density distribution, and radial distribution function. The cation radius, the hydration energy, and the preference of the inner/outer-sphere surface complex (ISSC/OSSC) all affected REC swelling. Because of the presence of asymmetric charges in the REC layer, interlayer cations tended to distribute on the surface of illite and formed an ISSC when they formed 1-, 2-, and 3-layer (1, 2, and 3 W) hydrate states. When the layer charge density of illite and Mmt was constant, only the layer charge position in Mmt was changed, and the REC swelling behavior was transformed into pure Mmt. The interlayer cations and the layer charge location significantly impacted the REC swelling.

Defect thermodynamics in spinel oxides leading to plasmonic behavior

Many optical devices can achieve enhanced performance at small scales by exploiting the surface plasmon resonance. Such a plasmonic material must have a large free carrier concentration. Although metals meet this criterion, their plasmon resonance cannot be chemically tuned into the infrared by varying the carrier concentration. By contrast, semiconducting oxides allow this tuning, and several spinel-structured oxides have shown plasmon resonance due to the easy dopability of spinels. This work uses first-principles calculations to identify the doping mechanism of these spinels, finding that Ga2FeO4 and Cd2SnO4 can be doped by cation antisites while Fe3O4 easily forms cation vacancies. In all three cases, the defect concentration can be tuned widely by controlling the chemical potentials of the different species. The chemically related Al2FeO4 is predicted to be much less dopable, indicating the need for careful design based on cation radius and other chemical factors to achieve good plasmonic performance, even in families such as spinels which have many dopable members.

Neutron Total Scattering Investigation of the Dissolution Mechanism of Trehalose in Alkali/Urea Aqueous Solution.

The atomic picture of cellulose dissolution in alkali/urea aqueous solution is still not clear. To reveal it, we use trehalose as the model molecule and total scattering as the main tool. Three kinds of alkali solution, i.e., LiOH, NaOH and KOH are compared. The most probable all-atom structures of the solution are thus obtained. The hydration shell of trehalose has a layered structure. The smaller alkali ions can penetrate into the glucose rings around oxygen atoms to form the first hydration layer. The larger urea molecules interact with hydroxide groups to form complexations. Then, the electronegative complexation can form the second hydration layer around alkali ions via electrostatic interaction. Therefore, the solubility of alkali aqueous solution for cellulose decreases with the alkali cation radius, i.e., LiOH > NaOH > KOH. Our findings are helpful for designing better green solvents for cellulose.

Template-free strategy for constructing N-doped hollow carbon sphere for broad operating potential supercapacitors

Nowadays, energy conversion devices have gradually gained attention while vigorously developing clean energy. Carbon materials are promising candidates for supercapacitors, but two issues have plagued the researchers. 1) Does the cation radius in the neutral electrolyte significantly impact the electrochemical performance of carbon materials? 2) How to introduce heteroatoms while constructing hollow structures in carbon spheres. This work proposes a facile template free strategy that uses aniline and pyrrole as nitrogen sources to synthesize carbon sphere precursors. High-temperature carbonization combined with alkali treatment leads to the formation of N-doped hollow porous carbon spheres. Robust wall structure (thickness is about 60–80 nm) and ideal surface structure (the specific surface area is 1079.9 m2 g−1) endow the carbon spheres with excellent electrochemical performance and outstanding cycle stability. The specific capacitance of the carbon spheres in Li2SO4 and Na2SO4 electrolytes under negative working potential (−0.8–0 V) are 378.4 and 367.6 F g−1, respectively, at a current density of 1 A g−1. After 5000 cycles, the capacitance retentions are 87.1% and 94.8% in Li2SO4 and Na2SO4 electrolytes. We inferred that the cation radius has a negligible effect on the specific capacitance of carbon materials, but has a more significant effect on the cycling stability and capacitance rate performance. It is hoped that this work can provide a reference for the subsequent construction of N-doped hollow carbon spheres and reasonable selection of electrolytes.

Friction in clay-bearing faults increases with the ionic radius of interlayer cations

Smectite can dramatically reduce the strength of crustal faults and may cause creep on natural faults without great earthquakes; however, the frictional mechanism remains unexplained. Here, our shear experiments reveal systematic increase in shear strength with the increase of the ionic radius of interlayer cations among lithium-, sodium-, potassium-, rubidium-, and cesium-montmorillonites, a smectite commonly found in faults. Using density-functional-theory calculations, we find that relatively small sodium ions fit in the ditrigonal cavities on the montmorillonite surfaces, resulting in weakening of interlayer repulsion during sliding. On the other hand, relatively large potassium ions do not fit in the ditrigonal cavities, resulting in a larger resistance to sliding due to electrostatic repulsion between potassium ions. Calculated shear strength is consistent with our shear experiments by considering the partial dehydration of the frictional contact area. These results provide the basis for developing a quantitative model of smectite-bearing fault rheology.

Visual investigation of simultaneous clay swelling and migration mechanisms and formation damage consequences using micromodels

One of the most important constituents of oil and gas reservoirs is clay minerals; they may cause formation damage by swelling and migration. When water with lower salinity than formation water invades clay-rich porous media, the clays absorb the water, which results in swelling and, therefore, limit the available space for fluids to flow. Clays may also detach from rock surfaces and start to migrate and block pore throats. Both mechanisms lead to permeability impairment as a critical formation damage element. A better understanding of damage due to clays helps us to control and overcome the problem, which affects oil recovery. In this work, the swelling and migration of clays are studied at the pore scale using clay coated micromodels. The effect of the composition and salinity of injected brines on sodium bentonite swelling and migration were visualized, investigated, and analyzed by a novel approach based on an image processing technique. The effect of simultaneous clay swelling and migration on porosity alteration at different sections of the micromodel was studied to estimate damage, qualitatively and quantitatively. Our experiments showed that the presence of KCl salt in the brine used in drilling, completion, and development operations is vital to control formation damage. The best damage remedy performance was reached when a salt with small hydrated radius cations, such as KCl is combined with a salt with divalent and small hydrated radius cations, such as CaCl2. The combination of KCl and CaCl2 showed only 2.8% reduction of porosity, while KCl showed around 7% reduction of porosity. In migration control, KCl showed the best ability to control migration and most of the migrated clays were re-adsorbed in the porous media.

Endo- and exohedral complexes of superphane with cations.

Quite recently it has been shown in a previous study that superphane, that is, [2.2.2.2.2.2](1,2,3,4,5,6)cyclophane, is a very convenient molecule in the study of endohedral complexes and especially in the study of the influence of the caged entity (i.e., guest) on the structure of the host molecule. This advantage results from the presence of two parallel benzene rings joined together by six quite flexible ethylene bridges (spacers). This article examines the energetic and structural properties of endo- and exohedral complexes of superphane with the following cations: H+ , Li+ , Na+ , K+ , Be2+ , Mg2+ , Ca2+ , B3+ , Al3+ , Ga3+ . The stability of endohedral complexes has been shown to be strongly dependent on the charge and radius of the caged cation. The inclusion of the cation inside the superphane molecule causes its 'swelling', which is manifested by an increase in the distance between the benzene rings and elongations of the ring and spacer C-C bonds. In the case of exohedral complexes, three forms are investigated: with the cation above the benzene ring, with the cation interacting with the superphane window in the equatorial position, and with the cation interacting with the center of the C-C spacer bond. The first of these forms has been shown to be preferred. The cation⋯acceptor distance depends on the cation radius. Among the cations investigated, H+ and Be2+ are particularly reactive and predisposed to induce significant structural changes in the superphane molecule, forming C-H bond or C-Be-C bridges, respectively.

Terahertz spectroscopy of citrate Salts: Effects of crystalline state and crystallization water

Citrate salts are widely used as food additives and medicines for health and treatment. Accurate and fast detection of citrate salts is most important in food industry and medicine health. In this work, terahertz (THz) time-domain spectroscopy was used to detect and analyze different citrate salts and differentiate their crystalline hydrates. Effects of the crystalline state, the crystallization water and the metal cation on the THz spectra of citrate salts were investigated. Results indicate the crystalline states of the citrate salt samples strongly influence their THz featuring absorption peaks and citrate salts with crystallization water have larger absorption coefficients at the same frequency and higher possibility of existing featuring absorption peaks in comparison with citrate salts without crystallization water. Size of the metal cation also influences the THz absorption peak of the citrate salt and a small cation radius results in a large absorption peak frequency. This work illustrates the terahertz spectroscopy can be well used as a new technique to detect the citrate salts and differentiate their crystalline hydrates.