Metal Iodates Research Articles

Metastable intermixed Core-shell Al@M(IO3)x nanocomposites with improved combustion efficiency by using tannic acid as a functional interfacial layer

As is known to all, the nano-aluminum (n-Al) of metastable intermixed composites (MICs) could be easily and slowly oxidized during long-term storage. Herein, a plant polyphenol, tannic acid (TA), has been used to coat n-Al as an interfacial layer to bind with metal iodates (Fe(IO3)3, Cu(IO3)3, Bi(IO3)3) forming MICs with tunable reactivity. The latter can be in-situ synthesized on the surface of TA to construct a core-shell n-Al@TA@M(IO3)x MICs suing a facile, green and low-cost chemical way. Various characterization techniques are used to investigate the prepared these core-shell MICs, including scanning electron microscopy, transmission electron microscopy, X-ray energy dispersive spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, thermal analysis, bomb calorimetry and high-speed camera. The results showed that the obtained novel MICs were almost monodispersed and uniformly distributed. They have shown enhanced performances in terms of thermal reactivity, long-term storage, energy releases and combustion efficiency. For the thermal reactivity, the major exothermic peak temperature of n-Al@TA@M(IO3)x can be reduced by about 16.9–48.6 °C by using TA as an interfacial layer in comparison with the mechanically mixed n-Al/M(IO3)x. For the long-term storage stability, the energy loss of n-Al@TA@Fe(IO3)3 (11.0%) after three weeks aging is much less than that of n-Al/Fe(IO3)3 (35.3%). For the energy release, Fe(IO3)3-based MICs can be increased to 24.1 kJ cm−3 (14.5% higher), whereas the Cu(IO3)3-based MICs to 22.8 kJ cm−3 (19.4%) and Bi(IO3)3-based MICs to 20.2 kJ cm−3 (3.1%). The burning rates of n-Al@TA@M(IO3)x are 1.7 to 4.3 times higher than that of n-Al/M(IO3)x, and the flame of n-Al@TA@M(IO3)x is more homogeneous than that of n-Al/M(IO3)x.

SrI3O9H: A new alkaline earth metal iodate with two different anionic units using mild aqua-solution method

An alkaline earth metal iodate crystal, SrI3O9H, has been successfully grown by a mild aqua-solution method for the first time. It contains two different anionic units, isolated [IO3] units and [I2O6H] units. The alkali and/or alkaline earth metal hydrogenous iodates (Ⅴ) are summarized. Thermal behavior, infrared spectrum, Raman spectrum, and UV–Vis–NIR diffuse reflectance spectrum are characterized. The band gap, density of states, and birefringence of SrI3O9H are calculated as well.

Morphology tuning of inorganic nanomaterials grown by precipitation through control of electrolytic dissociation and supersaturation

The precise control of the morphology of inorganic materials during their synthesis is important yet challenging. Here we report that the morphology of a wide range of inorganic materials, grown by rapid precipitation from a metal cation solution, can be tuned during their crystallization from one- to three-dimensional (1D to 3D) structures without the need for capping agents or templates. This control is achieved by adjusting the balance between the electrolytic dissociation (α) of the reactants and the supersaturation (S) of the solutions. Low-α, weak electrolytes promoted the growth of anisotropic (1D and 2D) samples, with 1D materials favoured in particular at low S. In contrast, isotropic 3D polyhedral structures could only be prepared in the presence of strong electrolyte reactants (α ≈ 1) with low S. Using this strategy, a wide range of materials were prepared, including metal oxides, hydroxides, carbonates, molybdates, oxalates, phosphates, fluorides and iodate with a variety of morphologies.

The ignition and combustion characteristics of Al/Ni(IO3)2·4H2O nanothermites

ABSTRACTNickel iodate tetrahydrate (Ni(IO3)2·4H2O) particles with different morphology and size were synthesized by precipitation method (PM) and electrospray precipitation method (EPM). The electrospray was used in chemical precipitation to synthesize nanoscale metal iodate particles with a narrow size distribution. The thermal decomposition mechanism of Ni(IO3)2·4H2O at different heating rates, ignition, and combustion of Al/Ni(IO3)2·4H2O nanothermites was studied by thermogravimetry–differential scanning calorimetry–mass spectrometry, T-jump and time-of-flight mass spectrometry, T-jump equipped with high-speed camera, and combustion cell test. The Al/Ni(IO3)2·4H2O prepared by EPM had a lower ignition temperature (587 ± 14°C) and a shorter burn time (159 µs). The ignition processes of Al/Ni(IO3)2·4H2O nanothermites prepared by EPM and PM were solid–solid and gas–liquid reactions, respectively. The rate-determining step of their combustion processes was the burning of aluminum powder and the decomposition of Ni(IO3)2· 4H2O, respectively.

Ce(IO3 )2 F2 ⋅H2 O: The First Rare-Earth-Metal Iodate Fluoride with Large Second Harmonic Generation Response.

The first rare earth metal iodate fluoride, Ce(IO3 )2 F2 ⋅H2 O, was synthesized by a hydrothermal method. In the structure, CeO5 F4 polyhedra connect with isolated IO3 groups to form 1D infinite [Ce(IO3 )2 F2 ] chains, which interconnect with each other by weak hydrogen bonds to construct the whole structure. Ce(IO3 )2 F2 ⋅H2 O produces a large second harmonic generation response, which is three times that of potassium dihydrogenphosphate. Theoretical calculations with DFT and dipole moments were performed to illustrate the relationships between the structure and the properties. The results show that Ce(IO3 )2 F2 ⋅H2 O is a new iodate fluoride with novel structure and potential applications in nonlinear optics.

Synthesis, structure and characterization of M(IO3)2(HIO3) (M = Ca, Sr) as new anhydrous alkaline earth metal bis-iodate hydrogeniodate compounds.

Two new metal iodates, namely, M(IO3)2(HIO3) (M = Ca, Sr), were successfully synthesized by the hydrothermal method, and their structures were determined by single-crystal X-ray diffraction. They were found to be isostructural, and crystallized in the monoclinic space group P21/n with the lattice parameters: a = 6.9647(14) Å, b = 15.719(3) Å, c = 7.2042(14) Å, β = 92.76(3)°, Z = 4 for Ca(IO3)2(HIO3), and a = 7.0697(14) Å, b = 15.986(3) Å, c = 7.3802(15) Å, β = 93.13(3)°, Z = 4 for Sr(IO3)2(HIO3). The structure featured a [HIO3]·[IO3]- complex with strong intermolecular interactions, and it was composed of [IO3]- anions and [HIO3]·[IO3]- complexes interconnected by Ca2+ or Sr2+ cations. The two compounds were characterized by X-ray diffraction, IR and Raman spectroscopies, UV-Vis diffuse reflectance spectroscopy, thermogravimetry and differential scanning calorimetry as well as by theoretical calculations.

Mo6+ Cation Enrichment of the Structure Chemistry of Iodates: Syntheses, Structures, and Calculations of Ba(MoO2)2(IO3)4O, Ba3[(MoO2)2(IO3)4O(OH)4]·2H2O, and Sr[(MoO2)6(IO4)2O4]·H2O

The three metal iodates Ba(MoO2)2(IO3)4O (1), Ba3[(MoO2)2(IO3)4O(OH)4]·2H2O (2), and Sr[(MoO2)6(IO4)2O4]·H2O (3) have been successfully synthesized by introducing second-order Jahn-Teller distorted Mo6+ cations by a mild hydrothermal method. Single-crystal X-ray diffraction (XRD) was used to determine the structures of the three title compounds. In compound 1, the [Mo2O11]10- dimers connect with the [IO3]- units by sharing oxygen atoms to form two-dimensional (2D) layers that are separated by the Ba2+ cations. For comparison, the [Mo2O11]10- dimers and the [IO3]- units are isolated in compound 2, and they are connected by the [BaO11]20- polyhedra forming a 3D network. For compound 3, the [MoO6]6- polyhedra link with each other by corner and edge sharing to build 2D corrugated layers with tunnels containing isolated [IO4]3- units. The [SrO9]16- polyhedra link the 2D corrugated layers to form a 3D network. The infrared (IR) spectra, the ultraviolet-visible-near-infrared (UV-vis-NIR) diffuse reflectance spectra, and thermal stabilities of compounds 1 and 2 are presented. In addition, the theoretical calculations are also carried out to evaluate their band gaps and density of states.

A Series of Mixed-Metal Germanium Iodates as Second-Order Nonlinear Optical Materials

A series of new compounds in the A/Ae-Ge4+-IO3 system, namely, A2Ge(IO3)6 (A = Li, Na, Rb, or Cs) and BaGe(IO3)6(H2O), have been obtained by introducing GeO6 octahedra into a ternary metal iodate system. The structures of all five new compounds feature a zero-dimensional [Ge(IO3)6]2– anion composed of a GeO6 octahedron connecting with six IO3 groups, the alkali or alkali-earth cations acting as spacers between these anions and maintaining charge balance. Interestingly, the isomeric Li2Ge(IO3)6 and Na2Ge(IO3)6 are noncentrosymmetric (NCS), whereas the isostructural Rb2Ge(IO3)6 and Cs2Ge(IO3)6 are centrosymmetric. BaGe(IO3)6(H2O) is the first NCS alkali-earth germanium iodate reported. Powder second-harmonic generation (SHG) measurements show that Li2Ge(IO3)6, Na2Ge(IO3)6, and BaGe(IO3)6(H2O) crystals are phase-matchable and display very large SHG signals that are approximately 32, 15, and 12 times that of KH2PO4, respectively, under 1064 nm radiation and 2, 0.8, and 0.8 times that of KTiOPO4, respectively,...

Acentric La3(IO3)8(OH) and La(IO3)2(NO3): Partial Substitution of Iodate Anions in La(IO3)3 by Hydroxide or Nitrate Anion.

Partial substitution of iodate anions in La(IO3)3 by OH- or NO3- anion led to acentric La3(IO3)8(OH) and chiral La(IO3)2(NO3). The structure of La3(IO3)8(OH) can be seen as a complex three-dimensional (3D) network composed of two-dimensional [La3(IO3)2(OH)]6+ cationic layers that are further bridged by remaining iodate anions, or alternatively as a 3D network composed of one-dimensional [La3(IO3)6(OH)]2+ cationic columns being further interconnected by additional iodate anions, while the structure of La(IO3)2(NO3) can be seen as a novel 3D structure with planar NO3 groups serving as linkage between the [La3(IO3)6]3+ triple layers. Compared to La(IO3)3, both compounds show considerably wide band gaps and enhanced thermal stability. La(IO3)2(NO3) shows a moderate second harmonic generation (SHG) response of ∼0.6 times that of KDP (KH2PO4), a wide band gap of 4.23 eV, and a high LDT value (22 × AgGaS2). Optical property measurements, thermal analysis, as well as theoretical calculations on SHG origin, were performed. It can be deduced that partial substitution of iodate anions can be a facile route to design new noncentrosymmetric metal iodates with novel structure and potential application.

One-step solvent-free mechanochemical synthesis of metal iodate fine powders

Metal iodates are strong iodine rich oxidizers which can be used in the formulation of biocidal energetic materials. Generally, metal iodates particles were synthesized by chemical precipitation methods with a large size distribution. In this work, we developed a one-step and solvent-free, high yield method to synthesize metal iodate fine powders by mechanochemistry. Compared to the conventional chemical precipitation method, the size of final products can be reduced by 20–500 times. The method generates particles with a narrower size distribution and high yield, and is sufficiently generic as to enable creation of a variety of metal iodates including AgIO3, Ca(IO3)2, Mn(IO3)2 and Cu(IO3)2. Moreover, the synthesis is conducted in the solid states with little to no solvent. The role of process conditions (temperature, hydration state, and milling time) on reaction products was investigated by TG/DSC and XRD. We believe that crystalline water bound to the metal nitrates precursor lowers the Tammann's temperature sufficient to unbind water so as to promote ion diffusion and thus facilitate reaction in the absence of a solvent. The reaction is promoted by the milling process which attrits the particles to expose fresh unreacted surfaces and reduces particle size.

Photoconversion Mechanisms and the Origin of Second-Harmonic Generation in Metal Iodates with Wide Transparency, NaLn(IO3)4 (Ln = La, Ce, Sm, and Eu) and NaLa(IO3)4:Ln3+ (Ln = Sm and Eu).

Four new metal iodates, namely, NaLn(IO3)4 (Ln = La, Ce, Sm, and Eu), and a series of NaLa(IO3)4:Ln3+ (Ln = Sm and Eu) solid solutions were synthesized through hydrothermal reactions. The structures of the title compounds are similar to that of NaY(IO3)4 crystallizing in the acentric monoclinic space group Cc. The iodate materials reveal layered structures composed of LnO8 square antiprisms and IO3 polyhedra, in which each layer is connected by the I···O interactions. NaLa(IO3)4 suggests a great potential as a matrix for optical source attributed to its acentricity and broad transparency from visible to mid-IR region. The photoluminescence properties depending on the concentration of Sm3+ reveal that NaLa(IO3)4:Sm3+ undergoes a self-quenching relaxation over 7 mol % of Sm3+ by dipole-quadrupole interactions. Attributable to the asymmetric coordination environment of Ln3+, stronger electric dipole transitions compared to magnetic dipole transitions were observed for both compounds. In addition, the materials exhibit strong second-harmonic generation (SHG) responses and are type I phase-matchable. The structural origin of the SHG properties for the reported iodates is elucidated.

Bi(IO3)F2: The First Metal Iodate Fluoride with a Very Strong Second Harmonic Generation Effect

AbstractThe first metal iodate fluoride, Bi(IO3)F2, with a strong second harmonic generation (SHG) effect has been prepared. Bi(IO3)F2 crystallizes in the polar space group C2 and features a three‐dimensional [BiF2]+ cationic framework with IO3 groups capping the inner walls of the one‐dimensional tunnels. This [BiF2]+ cationic framework acts as a template for the assembly of the polar IO3 units in a favorable superposed fashion, which leads to the polar structure of the material. Bi(IO3)F2 displays a rather wide transmittance window (0.3–11 μm) and exhibits a very strong SHG response that is about 11.5 times larger than that of KH2PO4 (KDP) under 1064 nm laser radiation and the same as that of KTiOPO4 (KTP) under 2.05 μm laser radiation. Preliminary investigations indicate that Bi(IO3)F2 is a promising nonlinear optical material in the visible and mid‐IR region.

Bi(IO3 )F2 : The First Metal Iodate Fluoride with a Very Strong Second Harmonic Generation Effect.

The first metal iodate fluoride, Bi(IO3 )F2 , with a strong second harmonic generation (SHG) effect has been prepared. Bi(IO3 )F2 crystallizes in the polar space group C2 and features a three-dimensional [BiF2 ]+ cationic framework with IO3 groups capping the inner walls of the one-dimensional tunnels. This [BiF2 ]+ cationic framework acts as a template for the assembly of the polar IO3 units in a favorable superposed fashion, which leads to the polar structure of the material. Bi(IO3 )F2 displays a rather wide transmittance window (0.3-11 μm) and exhibits a very strong SHG response that is about 11.5 times larger than that of KH2 PO4 (KDP) under 1064 nm laser radiation and the same as that of KTiOPO4 (KTP) under 2.05 μm laser radiation. Preliminary investigations indicate that Bi(IO3 )F2 is a promising nonlinear optical material in the visible and mid-IR region.

Direct Deposit of Highly Reactive Bi(IO3)3‐ Polyvinylidene Fluoride Biocidal Energetic Composite and its Reactive Properties

Metal iodate oxidizers are synthesized and evaluated as oxidizers in thermite reactions to generate both heat and a biocidal reaction product for bioagent defeat. TGA/DSC/MS and T‐jump TOFMS analysis show gas‐phase iodine release from metal iodate decomposition at both low and high heating rates. In constant volume combustion tests, Bi(IO3)3/Al thermite outperforms other metal iodate/Al and traditional thermites. Mechanically sound composites with high mass loadings of particulates are formed by direct electrospray of synthesized metal iodates, nanoaluminum fuel, and polyvinylidine fluoride (PVDF) binder/oxidizer, and burn speeds are measured in both air and argon atmospheres.

Metal Iodate-Based Energetic Composites and Their Combustion and Biocidal Performance.

The biological agents that can be weaponized, such as Bacillus anthracis, pose a considerable potential public threat. Bacterial spores, in particular, are highly stress resistant and cannot be completely neutralized by common bactericides. This paper reports on synthesis of metal iodate-based aluminized electrospray-assembled nanocomposites which neutralize spores through a combined thermal and chemical mechanism. Here metal iodates (Bi(IO3)3, Cu(IO3)2, and Fe(IO3)3) act as a strong oxidizer to nanoaluminum to yield a very exothermic and violent reaction, and simultaneously generate iodine as a long-lived bactericide. These microparticle-assembled nanocomposites when characterized in terms of reaction times and temporal pressure release show significantly improved reactivity. Furthermore, sporicidal performance superior to conventional metal-oxide-based thermites clearly shows the advantages of combining both a thermal and biocidal mechanism in spore neutralization.

ChemInform Abstract: The Orthoperiodates of Calcium, Strontium, and Barium.

AbstractM5(IO6)2 (M: Ca, Sr, Ba) are prepared by solid‐state reactions of metal iodides or metal iodates in air.

The Orthoperiodates of Calcium, Strontium, and Barium

AbstractOrthoperiodates of calcium, strontium, and barium were prepared by solid‐state reactions of metal iodides or metal iodates with oxygen in air. M(IO3)2 (M = Ca) or MI2 (M = Sr, Ba) were heated in an open corundum crucible to yield M5(IO6)2 as a product with beige to light brown body color. Reactions were investigated by thermal analyses, using differential thermal analysis (DTA) and thermogravimetric analysis (TGA). Two distinct crystal structures were assigned for M5(IO6)2 with the space group R$\bar {3}$c for M = Ca, Sr (isotypic with Ca, Sr perrhenates) and Pnma for M = Ba based on recorded powder X‐ray diffraction data. Luminescence properties of europium‐doped samples are reported.

First evidence of a phase transition in a high-pressure metal iodate.

In the 1970s, a large number of metal iodates compounds were extensively investigated for their nonlinear optics (NLO) properties as well as for their ferroelectric, piezoelectric, and pyroelectric properties. Interest in these compounds resumed in the early 2000s. We have shown that metal iodates are particularly interesting for for quadratic NLO in mid IR, as they possess a large domain of transparency from the visible region to the beginning of the far IR region (12.5 μm), thus covering the three atmospheric transparency windows. The synthesis of metal iodates has so far been mainly investigated by solution chemistry, under hydrothermal conditions or by the flux method. The solid state synthesis of these compounds at high pressure has never been explored. To date, only the structural evolution of α-LiIO3 with pressure has been studied by X-ray powder diffraction [1]. It was shown that, at room temperature, α-LiIO3 is stable up to 75 GPa; only compression of the lattice parameters with pressure was observed. In this work, we present a new phase of silver iodate obtained at high pressure from α-AgIO3 and characterized by X-ray powder diffraction. The α-AgIO3 to β-AgIO3 transition was characterized by differential thermal analysis (DTA) at high pressure [2-3]. The thermal behaviors of α-AgIO3 and β-AgIO3 were studied by differential scanning calorimetry (DSC) at ambient pressure and in situ temperature-dependent X-ray powder diffraction. Structural studies of these two phases were carried out to understand the formation of β-AgIO3.

ChemInform Abstract: First Evidence of a Phase Transition in a High‐Pressure Metal Iodate: Structural and Thermal Studies of AgIO3 Polymorphs.

AbstractA new phase of silver iodate, β‐AgIO3, is obtained by heating α‐AgIO3 at 2.7 GPa at <240 °C for 30 min.

First Evidence of a Phase Transition in a High‐Pressure Metal Iodate: Structural and Thermal Studies of AgIO3 Polymorphs

AbstractA new phase of silver iodate, β‐AgIO3, was obtained at 2.7 GPa by heating the α‐AgIO3 precursor above 240 °C. β‐AgIO3 is the first iodate obtained at high pressure that stabilizes under normal conditions. The crystal structure was determined by X‐ray powder diffraction and Rietveld refinement. In comparison to α‐AgIO3, which crystallizes in the Pbc21 acentric orthorhombic space group with the lattice parameters a = 7.265(2) Å, b = 15.17(4) Å, c = 5.786(2) Å, and V = 638(2) Å3, β‐AgIO3 crystallizes in the Pbca centric orthorhombic space group, with the following parameters: a = 6.137(2) Å, b = 16.980(4) Å, c = 5.827(1) Å, and V = 607.3(3) Å3. Differential thermal analysis under high pressure (2.7 GPa) and structural studies showed an endothermic transformation at 260 °C corresponding to a first‐order reconstructive phase transition from α‐AgIO3 to β‐AgIO3. The thermal behaviors of α‐AgIO3 and β‐AgIO3 were studied by differential scanning calorimetry at ambient pressure and in situ temperature‐dependent X‐ray powder diffraction.