Rare Earth Iodates Research Articles

Rational Design of Novel Polar Nonlinear Optical Materials in Alkali Metal Rare Earth Iodates.

Four new potassium rare earth iodates, namely, acentric K2Lu(IO3)5 and KM(IO3)4(HIO3)0.33 (M = Ce/Pr) and centric KLa(IO3)4, were successfully grown by mild hydrothermal reactions. Three of them exhibit polar structures; K2Lu(IO3)5, KCe(IO3)4(HIO3)0.33, and KPr(IO3)4(HIO3)0.33 show second-harmonic generation (SHG) responses of 3.0, 1.0, and 0.8 × KDP, respectively. These three iodates are phase-matchable for second-harmonic generation. The influence of changes in the radius and coordination mode of rare earth ions on the crystal structure and SHG response has been discussed in detail. Our findings suggest that in the alkali metal rare earth iodate, modulating the arrangement of iodate groups by changing the coordination geometry of rare earth ions is an effective strategy for designing polar NLO materials.

Effects of UV illumination on organic dye decomposition activity and antibacterial and antiviral activities of rare earth iodates

For this study, we investigated the effects of UV illumination on dye decomposition and antibacterial and antiviral activities of three rare earth iodates (Ce(IO3)4, Ce(IO3)3, and δ-La(IO3)3) that reportedly have antibacterial and antiviral activities in the dark. The objective of this study was to clarify whether bulk materials and eluted ions are involved in these activities under UV illumination. Findings indicate that Ce(IO3)3 and δ-La(IO3)3 exhibit dye degradation activity under UV illumination by a Hg-Xe lamp (7 mW/cm2), suggesting that the dye decomposition activity was caused mainly by photochemical reactions under UV with wavelengths less than 300 nm by Ce3+ and by IO3− ions eluted from the samples. The dye decomposition activity under UV illumination is expressed not only from the eluted ions but also from the bulk materials. UV illumination using a weak (0.1 mW/cm2) UV light from a black light bulb with wavelengths longer than 320 nm increased the antibacterial and antiviral activities of these materials. These results suggest that the increase in antibacterial and antiviral activities is attributable to the photocatalytic reaction of bulk materials. This study revealed that both the bulk and eluted ions are involved in these activities under UV illumination. The extent to which photochemical reactions caused by eluted ions and bulk material contribute to the decomposition activity of organic dyes and antibacterial and antiviral activities depends on the UV illumination wavelength and intensity. This study provides new insights into the use of rare earth iodates as inorganic antibacterial and antiviral materials.Graphical abstract

Antibacterial and antiviral activities of transparent PVA coating films prepared by using solutions containing eluted ions from rare earth iodates

AbstractAfter powders of three rare earth iodates (Ce(IO3)4, Ce(IO3)3, δ-La(IO3)3) were dispersed in water, the constituent ions were eluted. After filtration, polyvinyl alcohol was dissolved in the filtrated solution. Then the solution was flow-coated to form coating films on glass substrates. The obtained coating films exhibited high transmittance in the visible wavelength range. IO3− was confirmed from the IR spectra measured using the ATR method. Fine precipitates were observed in the coating. The amount was greater on the surface than inside. The coating films prepared from Ce(IO3)3 and δ-La(IO3)3 possessed high antibacterial and antiviral activities against Escherichia coli, Staphylococcus aureus, bacteriophage Qβ, and bacteriophage Φ6 in the dark. Moreover, they inactivated viruses adsorbed from the gas phase.

Preparation of rare earth iodates and their decomposition activity on organic dyes and antibacterial/antiviral activities

After amorphous Ce(IO3)4 powder was prepared using precipitation method at room temperature, powder samples of crystalline Ce(IO3)3, α-La(IO3)3 and δ-La(IO3)3 were prepared by calcining the precipitates formed by mixing the solutions. All samples eluted some constituent ions in the solution. The Ce(IO3)4 decomposed methylene blue and methyl orange in water in the dark. The valence of Ce measured before and after the decomposition reaction suggested oxidative decomposition by Ce(IV). These samples exhibited high antibacterial activity against Escherichia coli and Staphylococcus aureus, and also high antiviral activity against the non-enveloped virus bacteriophage Qβ and the enveloped virus bacteriophage Φ6. Moreover, these samples caused protein denaturation. It is conceivable that the adsorption of lanthanum and cerium ions leaked from the sample, the oxidation power of ions such as Ce(IV) and IO3−, and pH value affected these antibacterial and antiviral activities.

Wide‐Bandgap Rare‐Earth Iodate Single Crystals for Superior X‐Ray Detection and Imaging

Semiconductor-based X-ray detectors with low detectable thresholds become critical in medical radiography applications. However, their performance is generally limited by intrinsic defects or unresolved issues of materials, and developing a novel scintillation semiconductor for low-dose X-ray detection is a highly urgent objective. Herein, a high-quality rare-earth iodate Tm(IO3 )3 single crystal grown through low-cost solution processing is reported with a wide bandgap of 4.1 eV and a large atomic number of 53.2. The roles of IO and TmO groups for charge transport in the Tm(IO3 )3 are revealed with the structural difference between the [101] and crystal orientations. Based on anisotropic responses of material properties and detection performances, it is found that the [ ] orientation, the path with fewer IO groups, achieves a high resistivity of 1.02 × 1011 Ω cm. Consequently, a single-crystal detector exhibits a low dark current and small baseline drifting due to the wide bandgap, high resistivity and less ion migration of Tm(IO3 )3 , resulting in a low detection limit of 85.2 nGyair s-1 . An excellent X-ray imaging performance with a high sensitivity of 4406.6 µC Gyair -1 cm-2 is also shown in the Tm(IO3 )3 device. These findings provide a new material design perspective for high-performance X-ray imaging applications.

Hydrothermal synthesis of new mixed-oxoanion materials: Rare earth iodate sulfates Sm(IO3)(SO4) and Ln2(IO3)3(SO4)OH·3H2O (Ln = Sm, Eu, Dy)

Chemical systems that contain non-centrosymmetric anions with electron lone pairs promote the formation of non-centrosymmetric phases. To probe this approach in mixed anion systems, we investigated crystallization in iodate-sulfate systems under mild hydrothermal conditions. By using different SO4 concentrations, the Sm(IO3)(SO4) and Ln2(IO3)3(SO4)OH·3H2O (Ln = Sm, Eu, Dy) structures were synthesized. It was observed that the reaction was very sensitive to the sulfate concentration. The structures were determined by single-crystal X-ray diffraction, where Sm(IO3)(SO4) crystallizes in the monoclinic crystal system adopting the space group P21/c and Ln2(IO3)3(SO4)OH·3H2O (Ln = Sm, Eu, Dy) crystallize in the triclinic crystal system adopting the space group P 1‾.

Hydrothermal Synthesis of New Mixed-Oxoanion Materials: Rare Earth Iodate Sulfates Sm(Io3)(So4) and Ln2(Io3)3(So4)Oh•3h2o (Ln = Sm, EU, Dy)

Hydrothermal Synthesis of New Mixed-Oxoanion Materials: Rare Earth Iodate Sulfates Sm(Io3)(So4) and Ln2(Io3)3(So4)Oh•3h2o (Ln = Sm, EU, Dy)

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...

Synthesis, Crystal Structure, and Optical Properties of the First Alkali Metal Rare-Earth Iodate Fluoride: Li2Ce(IO3)4F2

The first alkali metal rare earth iodate fluoride, Li2Ce(IO3)4F2, was synthesized using hydrothermal method. This compound features a novel [CeI4O12F2]∞ infinite layer with each [CeO6F2] dodecahedr...

Incorporating rare-earth cations with moderate electropositivity into iodates for the optimized second-order nonlinear optical performance

Introduction of rare-earth cations with moderate electropositivity into the iodate system afford three noncentrosymmetric rare-earth iodates REn(IO3)3n(H2O) with optimized balance between SHG efficiency and optical band gaps.

Helix-constructed polar rare-earth iodate fluoride as a laser nonlinear optical multifunctional material.

The first trivalent rare-earth iodate fluoride nonlinear optical (NLO) crystal, Y(IO3)2F (YIF), was successfully designed and synthesized, featuring polarization-favorable helical chains constructed from trans-YO6F2 polyhedra and IO3 groups. It exhibited a suitable balance of a wide transparency range of 0.26-10.0 μm, high laser damage threshold (LDT) of 39.6 × AgGaS2, and moderate second harmonic generation (SHG) effect of 2 × KDP. A series of doped RE:YIF (RE = Pr, Nd, Dy, Ho, Er, Tm, and Yb) crystals were easily synthesized benefiting from the spring-shaped helix structure, which possess wide absorption and emission peaks as well as long lifetime, especially in the visible and near-infrared regions. Particularly, the remarkable fluorescence properties of Nd and Yb doped YIF crystals are comparable to and even better than those of traditional self-frequency doubling (SFD) crystals such as YAB, YCOB, and GdCOB. Thus, these RE-doped YIF crystals are promising laser SFD crystals. This work also indicated that constructing helical chains should be an effective strategy for the design of inorganic polar materials.

K8Ce2I18O53: a novel potassium cerium(iv) iodate with enhanced visible light driven photocatalytic activity resulting from polar zero dimensional [Ce(IO3)8]4- units.

Hydrothermally grown iodate, K8Ce2I18O53, featuring polar 0D [Ce(IO3)8]4- units, has shown the highest visible light driven (VLD) photocatalytic activity in metal iodates reported before. The enhanced VLD photocatalytic property results from a synergistic effect between the narrow band gap and polar 0D [Ce(IO3)8]4- units, as confirmed using first principles calculations.

Differences and Similarities between Lanthanum and Rare-Earth Iodate Anhydrous Polymorphs: Structures, Thermal Behaviors, and Luminescent Properties.

The Ln(IO3)3(HIO3)y (y = 1 or 1.33) compounds are isostructural with the La(IO3)3(HIO3)y phases, but thermal studies reveal different behaviors. On the one hand, the partial thermal decompositions of these lanthanide compounds lead to the Ln(IO3)3 formulation, with a room temperature structure different from the β-La(IO3)3 obtained from La(IO3)3(HIO3)y. On the other hand, the partial thermal decompositions of the La1-xLnx(IO3)3(HIO3)y compounds prepared with lanthanides ions (Ce, Pr, Nd, Sm, Eu, Gd, and Yb) lead to acentric β-La1-xLnx(IO3)3. As for β-La(IO3)3, reversible structural transitions from β-La1-xLnx(IO3)3 to centrosymmetric γ-La1-xLnx(IO3)3 are observed. Differential scanning calorimetry analyses of La1-xLnx(IO3)3 solid solutions show that the transition temperatures vary with the lanthanide concentration in the solid solution. A transition is observed only up to a certain fraction of lanthanide-ion substitution; this substitution limit decreases with the cationic radius of the lanthanide ion. Finally, the β-La1-xNdx(IO3)3 and β-La1-xYbx(IO3)3 phases are investigated by luminescence spectroscopy.

Hydrothermal synthesis of a chiral rare earth iodate (Gd(IO3)3 · H2O) showing the rare (3, 8)-connected (43)(4 · 62) (49 · 617 · 82) topology

In the presence of Cu(II) ions, a chiral rare earth iodate Gd(IO3)3 · H2O (crystallizing in P21 (no. 4) space group), was synthesized hydrothermally from Gd2O3 and HIO3; the structure is the topologically (3, 8)-connected (43)(4 · 62)(49 · 617 · 82) network, constructed from 3-connected trigonal nodes (I1, I3) and 8-connected tetragonal prism nodes (Gd1).

Hydrothermal Synthesis of Rare Earth Iodates from the Corresponding Periodates. Part 2. Synthesis and Structures of Ln(IO3)3 (Ln: Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er) and Ln(IO3)3×2H2O (Ln: Eu, Gd, Dy, Er, Tm, Yb).

AbstractFor Abstract see ChemInform Abstract in Full Text.

Hydrothermal Synthesis of Rare Earth Iodates from the Corresponding Periodates: II1). Synthesis and Structures of Ln(IO3)3 (Ln = Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er) and Ln(IO3)3 · 2H2O (Ln = Eu, Gd, Dy, Er, Tm, Yb)

AbstractSingle crystals of lanthanide iodates have been quickly grown by decomposition of the corresponding periodates under hydrothermal conditions. Single crystal X‐ray diffraction showed that two structure types form with the elements from Pr‐Yb, an anhydrous form for Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er and a dihydrate for Eu, Gd, Dy, Er, Tm, Yb. A detailed structure study is presented for one representative of each of these types, along with structure type and lattice parameters for the other materials.Tb(IO3)3: Space group P21/c, Z = 4, lattice dimensions at 120 K: a = 7.102(1), b = 8.468(1), c = 13.355(2)Å, β = 99.67(1)°; R1 = 0.034.Yb(IO3)3 · 2H2O: Space group P1¯, Z = 2, lattice dimensions at 120 K: a = 7.013(1), b = 7.370(1), c = 10.458(2)Å, α = 95.250(5), β = 105.096(5), γ = 109.910(10)°; R1 = 0.024.

Hydrothermal Synthesis of Rare Earth Iodates from the Corresponding Periodates: Structures of Sc(IO3)3, Y(IO3)3 · 2 H2O, La(IO3)3 · 1/2 H2O and Lu(IO3)3 · 2 H2O

Hydrothermal syntheses of single crystals of rare earth iodates, by decomposition of the corresponding periodate, are presented. This appears to be a generic method for making rare earth iodate crystals in a short period of time. Single crystal X-ray diffraction structures of the four title compounds are presented. Sc(IO3)(3): Space group R(3), Z = 6, lattice dimensions at 100 K; a = b = 9.738(1), c = 13.938(1) A; R-1 = 0.0383. Y(IO3)(3) · 2H(2)O: Space group P(1), Z = 2, lattice dimensions at 100 K: a = 7.3529(2), b = 10.5112(4), c = 7.0282(2) A, ? = 105.177(1)°, ? = 109.814(1)°, ? = 95.179(1)°; R-1 = 0.0421. La(IO3)(3) · o H(2)O: Space group Pn, Z = 2, lattice dimensions at 100 K: a = 7.219(2), b = 11.139(4), c = 10.708(3) A, ? = 91.86(1)°; R-1 = 0.0733. Lu(IO3)(3) · 2H(2)O: Space group P(1), Z = 2, lattice dimensions at 120 K: a = 7.2652(9), b = 7.4458(2), c = 9.3030(3) A, ? = 79.504(1)°, ? = 84.755(1)°; ? = 71.676(2)°; R-1 = 0.0349.

Thermal and dielectric properties of rare earth iodates

The thermal (TGA, DTA and DSC) and dielectric behaviour of all rare earth iodates (except prometheum) has been investigated. The iodates of lanthanum, cerium to europium and gadolinium to lutetium decompose differently and the activation energies for these decomposition reactions have been determined. The DSC measurements have shown that all of the anhydrous iodates undergo one or more exothermic/endothermic changes. From the nature of the DSC profiles, heat of transitions, and powder diffraction data the phase transformations of Ln (IO3)3 have been found to occur in four different ways (lanthanum, cerium to europium, gadolinium to terbium, dysprosium to lutetium). Dielectric measurements of Ln (IO3)3 at varying temperature have corroborated the observations made with DSC studies. Relatively low dielectric constants of the high-temperature phases probably indicate their centrosymmetric structures. The dielectric behaviour of noncentrosymmetric Ln (IO3)3·H2O (Ln=cerium to samarium) has been investigated in the temperature range 30 to −160° C. They have high dielectric constants (er, ~ 1800 to 2400) at the ambient temperature and do not show significant change in the entire temperature range of investigation.

Phase transition behavior of rare earth iodates

Phase transition behavior of rare earth iodates

Paramagnetic Gd(IO3)3. Crystal structure of the transition metal iodates. IV

Gd(IO3)3, type I, crystallizes in the monoclinic system with space group P21/a and four formulas in the unit cell. The lattice constants, at 297 °K, are a=13.4365(9), b=8.5226(5), c=7.1356(5) Å and β=99.717(7) ° for λCuKα1=1.540598 Å. A total of 5012 independent reflections were measured on a CAD-4 diffractometer, using Nb-filtered MoKα radiation. The crystal structure was solved using a combination of Patterson and Fourier series, and was refined by the method of least squares. The final agreement factor R is 0.033. The iodate ions form a three-dimensional network based on shared oxygen atoms, with the Gd3+ ion located within a distorted dodecahedron of oxygen atoms. The three independent IO−3 ions form triangular pyramids, with three short I–O bonds of average length 1.803 Å and average O–I–O angle of 98.7°. Each I atom has three additional oxygen neighbors at distances in the range 2.741–3.194 Å that complete its distorted octahedron. Gd(IO3)3, type I is the archetype for an isostructural family of of rare-earth iodates extending from Ce to Lu. By contrast, no more than five (including Pm) rare-earth ions are represented in any of the other five known types of anhydrous rare-earth iodates. Small variations from monotonic in the lattice constants of type I anhydrous iodates are found, as predicted by the ’’tetrad’’ effect.