Metal Iodates Research Articles

Novel experimental methodology and optical analysis of (Ni, Co, Fe, and Cr) iodate nanocrystals

We reported a new experimental approach for a cost-effective production route towards the nanoparticles of 3d transition metal iodates of cobalt Np-CoI, Nickel Np-NiI, Iron Np-FeI and Chrome Np-CrI, exhibit nonlinear optical behavior. This soft chemistry method, we named the Hebboul's saturated solution method, creates the necessary nanoparticles in a couple of minutes demonstrate its usefulness in this family of metal iodate. By using X-ray diffraction, scanning electron microscopy, EDX, and FTIR spectroscopy, the produced samples have been evaluated. Identification of nanocrystal agglomerations was made easier by SEM analysis, XRD and EDX. Furthermore, XRD allowed researchers to determine that the average nanocrystal size of Np-CoI, Np-FeI, and Np-NiI are 13 nm, 17 nm, and 53 nm, respectively. From UV-V analysis, it was determined that the optical bandgap of the pure nanoparticles Np-CoI, Np-FeI, Np-NiI and Np-CrI was, respectively, 3.6 eV, 3.04 eV, 2.61 eV and 3.23 eV.

Highly Sensitive and Selective Gas Sensors Based on Metal Iodates: Material Characterization and Sensor Performance Evaluation.

This study proposes the possibility of employing metal iodates as novel gas-sensing materials synthesized using a facile chemical precipitation method. An extensive survey of a library of metal iodates reveals that cobalt, nickel, and copper iodates are useful for gas sensor applications. Material analysis conducted using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, thermal gravity differential temperature analysis, and Raman spectroscopy enables us to understand the thermal behavior and optimize post-annealing conditions. The evaluation of the gas-sensing performance of the specified metal iodates indicates that all of them display p-type sensing behavior and exhibit a high gas response toward different gases: a gas response of 18.6 by cobalt iodate to 1.8 ppm of acetone, a gas response of 4.3 by nickel iodate to 1 ppm of NO2, and a gas response of 6.6 by copper iodate to 1.8 ppm of H2S. Further investigation of the temperature-programmed reduction of H2 and polarization-electric field hysteresis analyses elucidates that the high gas response originates from the inherent characteristics of metal iodates, such as the high oxygen-reduction ability of iodine, highlighting the potential of the iodates as novel gas-sensing materials.

Pressure-induced band-gap energy increase in a metal iodate

A wide band gap is one of the essential requirements for metal iodates to be used as nonlinear optical materials. Usually, the band gap of these materials decreases under the application of pressure. Herein, we introduce a case in which the band-gap energy of a hydrated metal iodate, namely $\mathrm{Ca}{({\mathrm{IO}}_{3})}_{2}\ifmmode\cdot\else\textperiodcentered\fi{}{\mathrm{H}}_{2}\mathrm{O}$, has been successfully increased, from 4.52 to 4.92 eV, by applying external pressure without showing signs of saturation upon increasing pressure. The pressure-induced nonlinear band-gap opening correlates with the pressure-induced shortening of the I-O bond distances, as obtained from x-ray diffraction measurements. In addition, two pressure-induced isostructural phase transitions are observed in the pressure regions of 6.6--8.0 and 13.0--15.5 GPa. These two isostructural phase transitions cause a nonlinear pressure-induced evolution of the band-gap energy and crystal lattice parameters, as well as the occurrence of several extra peaks and peak splitting in Raman spectra.

Effect of alkali metal perchlorate and iodate type on boron ignition: The role of oxidizer phase change

Boron often demonstrates low reactivity despite having high gravimetric and volumetric energy density. Here we explore a family of oxidizers with very similar chemistries to understand controlling mechanisms in boron ignition. Alkali metal perchlorates as well as iodates (LiClO4, NaClO4, KClO4, LiIO3, NaIO3 and KIO3) were investigated under rapid heating conditions (∼105 K/s) by temperature-jump (T-Jump) ignition and time-of-flight mass spectrometry (TOFMS). T-Jump ignition tests in atmospheric pressure argon show that B/LiClO4, B/NaClO4, B/LiIO3, and B/NaIO3 ignite while B/KClO4 and B/KIO3 do not, despite the near identical chemistries. T-Jump TOFMS results demonstrate a dramatic increase of Cl and I containing species for Li and Na systems relative to K when B is added. Thermogravimetry/differential scanning calorimetry (TGA/DSC) analysis reveals that there is a temperature gap between melting and decomposition onset of LiClO4, NaClO4, LiIO3, and NaIO3, respectively, whereas KClO4 and KIO3 melt and decompose concurrently. We find that the larger interval between melting and decomposition renders more time for the oxidizer to melt and surround/wet the nanoscale B before decomposing, providing instant access to oxygen for B nanoparticles that results in vigorous ignition. This study of a set of equivalent oxidizers illustrates the important role of transport phenomena and physical properties have on ignition.

General relationship between the band-gap energy and iodine-oxygen bond distance in metal iodates

A wide band gap is a fundamental requirement for an ideal nonlinear optical material. A two-step investigation has been implemented to determine the relationship between the band-gap energy and the iodine-oxygen bond distance in optically nonlinear metal iodate materials. Firstly, we utilized high-pressure conditions on Mg and Zn iodates to correlate the pressure-induced changes in band-gap energy with changes in the iodine-oxygen bond distances. On both cases, the band-gap energy shows a nonlinear decrease under compression. The nonlinear behavior is a consequence of the interplay between the pressure-induced increase of the first-nearest neighbor iodine-oxygen bonds, which favors a narrowing of the band gap, and the decrease of the second-nearest neighbor iodine-oxygen bonds, which favors an opening of the band gap. The inverse correlation between the band-gap energy and the iodine-oxygen bond distance is confirmed in the second part of the investigation by collating and comparing the band-gap energies and corresponding average iodine-oxygen bond distances of the metal iodates reported in the literature. In the comparison, only nontransition and closed-shelled transition metals were included, without regard for their chemical formula, crystal structure, or stoichiometry.

Polar lanthanide copper iodates LnCu(IO3)5 (Ln = La, Ce, Pr, and Nd): Synthesis, crystal structure and characterization

Four new polar lanthanide copper iodates LnCu(IO3)5 (Ln ​= ​La, Ce, Pr, and Nd) were synthesized by the hydrothermal method at 220 ​°C. The four compounds are isostructural and they can be viewed as derivation from two parts: the [Ln(IO3)3] layers from the Ln(IO3)3 with 3D framework and the [Cu(IO3)2] chain from the α-Cu(IO3)2 with 2D layer structure. As the compounds crystallize in the noncentrosymmetric orthorhombic space group Pna21, they may find interesting applications as nonlinear optical crystals. The second-harmonic generation (SHG) response of powder LaCu(IO3)5 is measured to be around 0.5 times that of KDP. The measurement of SHG response versus particle sizes of samples indicates that LaCu(IO3)5 can achieve phase matching. In order to interpret the origination of SHG effects, the dipole moment of LaO9, CuO6 and IO3 groups were calculated. It is suggested that the IO3 groups contribute mostly (∼90.7%) and the CuO6 groups contribute little (∼1.6%) to the SHG response of LaCu(IO3)5. The results of this research show that the combination of lanthanide and copper elements with the electron lone-pair I5+ cations can be a feasible way to fabricate new polar materials in the rare-earth and transition metal iodate system.

Potential Skyrmion Host Fe(IO3)3: Connecting Stereoactive Lone-Pair Electron Effects to the Dzyaloshinskii-Moriya Interaction

Magnetic skyrmions, which are topologically distinct magnetic spin textures, are gaining increased attention for their unique physical properties and potential applications in spintronic devices. Here we present a design strategy for skyrmion host candidates based on combinations of magnetic spin, asymmetric building units having stereoactive lone-pair electrons, and polar lattice symmetry. To demonstrate the viability of the proposed rational design principles, we successfully synthesized a Fe(IO3)3 polycrystalline sample and single crystals by using a new simplified low-temperature pathway, which is experimentally feasible for extending materials growth of transition metal iodates. Single crystal X-ray and powder synchrotron X-ray diffraction measurements demonstrated that Fe(IO3)3 crystallizes in the polar chiral hexagonal lattice with space group P63. The combined structural features of the macroscopic electric polarization along the c-axis stemming from the coalignment of the stereoactive lone-pairs of the IO3– trigonal pyramid and the magnetic Fe3+ cation residing on the 3-fold rotation axis were selected to promote asymmetric exchange coupling. We find evidence of a predicted skyrmion phase at 14 K ≤ T ≤ 16 K and 2.5 T ≤ μ0H ≤ 3.2 T driven by a Dzyaloshinskii–Moriya (DM) interaction, a conclusion supported by the appreciable DM exchange and the zero-field spiral antiferromagnetic ground state of Fe(IO3)3 deduced from neutron diffraction experiments. The associated magnetic modulation wavelength of the putative skyrmions is expected to be short ∼18 nm, comparable to the period of the DM-driven incommensurate order. This work links stereoactive lone-pair electron effects to enhanced DM interaction, demonstrating a new approach for chemical guidelines in the search for skyrmionic states of matter.

High-Performance Second-Harmonic-Generation (SHG) Materials: New Developments and New Strategies.

ConspectusSecond-harmonic-generation (SHG) causes the frequency doubling of light, which is very useful for generating high-energy lasers with specific wavelengths. Noncentrosymmetry (NCS) is the first requirement for an SHG process because the SHG coefficient is zero (χ2 = 0) in all centrosymmetric structures. At this stage, developing novel NCS crystals is a crucial scientific topic. Assembling polar units in an addictive fashion can facilely form NCS crystals with outstanding SHG performance. In this way, our group has obtained many different NCS crystals with extremely large SHG intensities (>5 × KDP or 1 × KTP). In this Account, we first provide a brief review of the development of SHG materials and concisely highlight the features of the excellent SHG materials. Then, we present four facile and rational molecular design strategies: (1) Traditional BO33--based crystals feature short absorption edges but usually suffer from relatively weak SHG performance (<5 × KDP). The combination of two types of pure π-conjugated anions (BO33- and NO3-) in a parallel fashion in the same compound has afforded a metal borate nitrate with a strong SHG effect. (2) To overcome the problems of the weak SHG effect and small birefringence in the less anisotropic QO4-based compounds, highly polarizable cations such as Hg2+ and Bi3+ are introduced into these systems, which greatly enhances both SHG effects and birefringence. (3) Iodate anions can be condensed into polynuclear iodate anions with a higher density of I5+ per unit cell, hence polyiodate anions can serve as excellent SHG-active groups. We developed a novel synthesis method for hydrothermal reactions under a phosphoric acid medium and obtained a series of metal polyiodates with strong SHG effects. In addition, as the number of iodate groups increases, the structural configuration of the polyiodate anion changes from linear to bent. (4) We introduce the concept of aliovalent substitution which features site-to-site atomic displacement at the structural level. Such aliovalent substitution led to new materials that have the same chemical stoichiometries or structural features as their parent compounds. Thus, aliovalent substitution can provide more experimental opportunities and afford new high-performance SHG materials. The introduction of a fluoride anion and the replacement of metal cations in the MO6 octahedron can result in new metal iodates with balanced properties including a large SHG effect, a wide band gap, and a high laser-induced damage threshold (LIDT) value. Finally, we briefly discuss several problems associated with the studies of SHG materials and give some prospects for SHG materials in the future.

A New Anhydrous Polar Rare-Earth Iodate Fluoride, Ce(IO3)2F2, Exhibiting a Large Second-Harmonic-Generation Effect and Improved Overall Performance

A new anhydrous rare-earth metal iodate fluoride, Ce(IO3)2F2, was rationally designed and synthesized. Ce(IO3)2F2 features unique zigzag ∞[CeF2]2+ chains that are bridged by IO3– groups, creating a...

Na7(IO3)(SO4)3: the first noncentrosymmetric alkaline-metal iodate-sulfate with isolated [IO3] and [SO4] units.

Metal iodates are of current research interest because of their potential application as nonlinear optical crystals but the exploration of new iodates is mainly concentrated on complex cation iodates. In contrast, iodates with multiple anion groups are rarely reported. In this communication, the first noncentrosymmetric alkaline-metal iodate-sulfate, Na7(IO3)(SO4)3 has been designed, synthesized and characterized.

Scintillation materials based on metal iodates by rare earth doping modifications for use in radioluminescence and X-ray imaging

We obtained metal iodates scintillators with high X-ray response and scintillating films with high X-ray sensitivity and imaging spatial resolution.

High Coordinate Metal Iodate Chlorides with Diverse Structural Motifs and Tunable Birefringence

Metal iodates with large polarizability have long been overlooked as potential birefringent materials. By introducing highly coordinated Ba- and La-based MOnClm polyhedra into an iodate system, we ...

Ba(IO3)F: An Alkaline-Earth-Metal Iodate Fluoride Crystal with Large Band Gap and Birefringence.

An alkaline-earth-metal iodate fluoride, Ba(IO3)F (1), was discovered by introducing F atoms into alkaline-earth-metal iodates via a hydrothermal method. The pseudo-two-dimensional (2D) [BaF]+ layers and [IO3]- anionic groups built the crystal structure, which obviously exhibited large anisotropies. The birefringence of 1 was initially tested to be 0.1256 at 589.3 nm. Besides, compared with most reported metal iodate crystals, 1 possesses a large band gap (Eg = 4.32 eV). Theoretical calculations proved that the excellent optical characteristics can be attributed to [IO3]- anionic groups and [BaO4F4]10- polyhedra.

Dimensionality–Band Gap–Third-Harmonic Generation Property Relationship in Novel Main-Group Metal Iodates

Three new main-group metal iodates, i.e., AgGa(IO3)4, AgIn(IO3)4, and Ag3In(IO3)6, have been successfully synthesized by hydrothermal reactions at different temperatures. Single crystal X-ray diffr...

K2Na(IO3)2(I3O8) with Strong Second Harmonic Generation Response Activated by Two Types of Isolated Iodate Anions

A new alkali metal iodate, K2Na(IO3)2(I3O8), has been synthesized using the mild hydrothermal method, which is the first example of noncentrosymmetric iodate containing isolated [IO3]− and [I3O8]− groups. To the best of our knowledge, it exhibits the largest second harmonic generation response among the iodates with two types of isolated I–O groups (7.6 × KH2PO4 (KDP) @1064 nm). It also possesses a moderate birefringence (Δn) of 0.055 at 1064 nm for achieving its phase matching and a wide band gap (3.83 eV) for obtaining a high laser damage threshold, which assures that it possesses a high laser-induced damage threshold (LDT, 13 × AgGaS2). These results indicate that it is a good candidate for nonlinear optical applications.

(NH4 )Bi2 (IO3 )2 F5 : An Unusual Ammonium-Containing Metal Iodate Fluoride Showing Strong Second Harmonic Generation Response and Thermochromic Behavior.

An ammonium-containing metal iodate fluoride compound, (NH4 )Bi2 (IO3 )2 F5 , featuring a two-dimensional double-layered framework constructed by [BiO2 F5 ]6- and [BiO4 F4 ]9- polyhedra, as well as [IO3 ]- groups, was successfully synthesized. The well-ordered alignment of these SHG-active units leads to an extraordinary strong SHG response of 9.2 times that of KDP. Moreover, this compound possesses a large birefringence (Δn=0.0690 at 589.3 nm), a wide energy band gap (Eg =3.88 eV), and a high laser damage threshold (LDT; 40.2×AgGaS2 ). In particular, thermochromic behavior was observed for the first time in this type of compound. Such multifunctional crystals will expand the application of nonlinear optical materials.

(NH4)Bi2(IO3)2F5: An Unusual Ammonium‐Containing Metal Iodate Fluoride Showing Strong Second Harmonic Generation Response and Thermochromic Behavior

AbstractAn ammonium‐containing metal iodate fluoride compound, (NH4)Bi2(IO3)2F5, featuring a two‐dimensional double‐layered framework constructed by [BiO2F5]6− and [BiO4F4]9− polyhedra, as well as [IO3]− groups, was successfully synthesized. The well‐ordered alignment of these SHG‐active units leads to an extraordinary strong SHG response of 9.2 times that of KDP. Moreover, this compound possesses a large birefringence (Δn=0.0690 at 589.3 nm), a wide energy band gap (Eg=3.88 eV), and a high laser damage threshold (LDT; 40.2×AgGaS2). In particular, thermochromic behavior was observed for the first time in this type of compound. Such multifunctional crystals will expand the application of nonlinear optical materials.

From centrosymmetric to noncentrosymmetric: intriguing structure evolution in d10-transition metal iodate fluorides.

Two new d10-transition metal iodate fluorides, centrosymmetric ZnIO3F and noncentrosymmetric CdIO3F, were successfully synthesized by intriguing structure evolution. Both compounds have higher thermal stability and CdIO3F has a large SHG response and wide band gap. Our study may afford a viable route to design materials with excellent NLO functions.

Synthesis of metal iodates from an energetic salt.

Iodine containing oxidizers are especially effective for neutralizing spore forming bacteria by generating iodine gas as a long-lived bactericide. Metal iodates have been shown to be strong oxidizers when combined with aluminum fuel particles for energy generating applications. One method to produce metal iodates in situ is by using metal oxides and an energetic salt: aluminum iodate hexahydrate (Al(H2O)6(IO3)3(HIO3)2), which is called AIH. In this study, the thermal stability and reactivity of AIH with metal oxides commonly used in energetic formulations was investigated. Three metal oxides: bismuth(iii) oxide (Bi2O3), copper(ii) oxide (CuO), and iron(iii) oxide (Fe2O3) were investigated because of their different oxygen release properties. Each metal oxide powder was combined with AIH powder. Thermal stability and reactivity were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) and reactive properties calculated to supplement experimental observations. Powder X-ray diffraction (XRD) was also used to identify the product species at various stages of heating corresponding to exothermic activity. Results show that AIH decomposition is entirely endothermic but, with the addition of metal oxide powder to AIH, exothermic reactions transform metal oxides into more stable metal iodates. This analysis provides an understanding of the compatibility of AIH with metal oxides and contributes to the development of novel energetic composites that have the advantages of both thermal and biocidal mechanisms for spore neutralization.

Synthesis, structure, and third-harmonic generation measurements of a mixed alkali metal iodate, KLi2(IO3)3

Pure polycrystalline samples and single crystals of a mixed alkali metal iodate, KLi2(IO3)3 were synthesized through standard solid state and hydrothermal reactions, respectively, by using Li2CO3, K2CO3, and I2O5 as reagents. Single-crystal X-ray diffraction analysis suggests that KLi2(IO3)3 exhibits a corrugated layered structure consisting of IO3 distorted trigonal pyramids, LiO4 tetrahedra, and K+ cations. Within the layer, both five-membered rings (5-MRs) and six-membered rings (6-MRs) exist. UV–vis diffuse reflectance spectral data suggest that KLi2(IO3)3 has a wide optical band gap of ca. 4.25 ​eV. Infrared spectrum of the title compound clearly confirms the existence of IO3 groups in the backbone. The framework of the iodate is thermally stable to ca. 450 ​°C. Third-harmonic generation measurements using 1500 ​nm radiation indicate that the third-order nonlinear optical susceptibility of KLi2(IO3)3 is ca. 3 times that of α-SiO2. The laser-induced damage threshold of KLi2(IO3)3 is comparable to that of α-SiO2. Calculated local dipole moment values of IO3 polyhedra are also reported to better understand the asymmetric coordination environment.