Ho Ions Research Articles

Preparation of Bi@Ho3+:TiO2/Composite Fiber Photocatalytic Materials and Hydrogen Production via Visible Light Decomposition of Water

Using electrospun nanofibers doped with TiO2 and rare-earth ion Ho3+ as the matrix, and sodium gluconate as the reducing agent, Bi(NO3)3 was reduced using hydrothermal technology to produce Bi@Ho3+:TiO2 composite fiber materials. The materials’ phase, morphology, and photoelectric properties were characterized using various analytical testing methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), and transient photocurrent (IP). During the hydrothermal process, it was confirmed that Bi3+ was reduced by sodium gluconate to form pure Bi nanoparticles, which combined with Ho3+:TiO2 nanofibers to form heterojunctions. By leveraging the surface plasmon resonance (SPR) effect of metallic Bi and the abundant energy level structure and 4f electron transition properties of rare-earth Ho3+, the TiO2 nanofibers underwent dual modification, effectively enhancing the photocatalytic activity and stability of TiO2. Under visible light irradiation, the rate of hydrogen production through water decomposition reached 43.6 μmol·g−1·h−1.

Tailoring magnetic properties of novel (La0.25Nd0.25Sm0.25Gd0.25)1-xHoxMnO3 high-entropy perovskite ceramics by Ho doping

High-entropy perovskite ceramics (HEPCs) with equal atomic ratios have recently emerged as a highly promising class of materials due to their unique magnetic properties. However, the crystal structure, microstructure and magnetic properties of unequal atomic ratios HEPCs have yet to be fully investigated. In this paper, single-phase HEPCs (La0.25Nd0.25Sm0.25Gd0.25)1-xHoxMnO3 ((LNSG)1-xHxMO) have been synthesized using solid-state reactions. The effect of Ho element content (x = 0.25, 0.3, 0.35 and 0.4) on the structure and magnetic properties was systematically investigated. All samples exhibit an orthorhombic perovskite structure with a Pbnm space group and show obvious crystallization characteristics after sintering at 1250 °C for 16 h (LNSG)1-xHxMO HEPCs display a smooth surface texture and distinct grain boundaries, as well as significant hysteresis effects at T = 5 K. The spin-orbit interaction and magnetic anisotropy between Ho and Mn ions increase with the increase of Ho content, which increases the saturation magnetization (Ms) of HEPCs. (LNSG)0.6H0.4MO exhibits the lowest magnetic hysteresis losses among the considered samples, attributed to its highest Ms (50.95 emu/g) and the lowest coercivity Hc (0.6 kOe). These characteristics endow it with a potential application in magnetic storage devices.

Detailed scrutiny of FWM in holmium-doped fiber amplifier (HOFA) in WDM systems

Abstract Four wave mixing (FWM) in wavelength division multiplexed (WDM) systems is prominent performance degrading nonlinearity and limits the total capacity of the system. FWM is explored in different fiber optical amplifiers such as erbium-doped fiber amplifier (EDFA), Raman fiber amplifier (RFA), and also in semiconductor optical amplifier (SOA). Reported studies in HOFA revealed that nonlinear effects in these amplifiers are low; however, in present study, in this research article WDM-HOFA system has been simulated and studied FWM in detail at different HOFA parameters such as input power, length, core radius, doping radius, numerical aperture (NA), Ho ion density, and effects of co- and counter-pumping. Gain and noise figure (NF) are also investigated at aforementioned parameters, and performance is evaluated in terms of optical signal to noise ratio (OSNR) at 2,030 nm wavelength window. It is observed that least FWM obtained at 3 m Ho fiber length, 2 µm core radius and doping radius, 15.6 × 1023 m−3 Ho ion doping, 0.1 NA, −10 dB input power, 0.8 GHz channel spacing, and 4 WDM channels. However, better gain and NF comes at different values of these parameters, and as a result, there is trade-off between FWM and gain, NF.

Effect of Lanthanide Ions and Triazole Ligands on the Molecular Properties, Spectroscopy and Pharmacological Activity.

The effect of La, Ce, Pr and Nd ions on four Ln(ligand)3 complexes and at three DFT levels of calculation was analyzed. Four ligands were chosen, three of which were based on the 1,2,3-triazole ring. The DFT methods used were B3LYP, CAM-B3LYP and M06-2X. The relationships established were between the geometric parameters, atomic charges, HOMO-LUMO energies and other molecular properties. These comparisons and trends will facilitate the synthesis of new complexes by selecting the ligand and lanthanide ion best suited to the desired property of the complex. The experimental IR and Raman spectra of Ln(2b')3 complexes where Ln = La, Ce, Pr, Nd, Sm, Gd, Dy, Ho and Er ions have been recorded and compared to know the effect of the lanthanide ion on the complex. The hydration in these complexes was also analyzed. Additionally, the effect of the type of coordination center on the ability of an Ln(ligand)3 complex to participate in electron exchange and hydrogen transfer was investigated using two in vitro model systems-DPPH and ABTS.

Low-temperature magnetism of Ln2Ba (Ln = Nd, Er, Ho) furoate-based polymeric chains: Slow relaxation, magnetic anisotropy and interactions

The synthesis, structure and magnetothermal properties of three new lanthanide 1D polymeric complexes, {[Ln2Ba(α-fur)8(H2O)4]}n for Ln = Nd (1), Er (2) and {[Ho2Ba(α-fur)8(H2O)4]⋅2H2O}n (3), based on carboxylic α-fur = C4H3OCOO ligands is reported. The α-furoate ligands consolidate zigzag chains formed by Ln2 dimers separated by Ba ions. Ab initio calculations, in combination with the fit of experimental static magnetization and heat capacity, predict the magnetic ground state, energy levels and magnetic interactions in these heteronuclear nanomagnets. Nd2Ba (1) presents two different coordination sites for Nd, with an orthorhombic magnetic ground state. Nd ions are coupled along the chain through a weak antiferromagnetic (AF) interaction J″/kB = −0.08 K. Er(III) ions in Er2Ba (2) present a highly axial ground state, forming magnetic dimers with an interaction of J′/kB = −8.6 K, while interdimer coupling along the chain is J″/kB = −0.28 K. The Ho2Ba (3) complex consists of a highly anisotropic quasi-doublet with a ΔHo/kB = 0.7 K gap. Non-Kramers Ho ions form magnetic dimers within the Ho2Ba cluster, coupled by an AF intradimer interaction J′/kB = −2.5 K. The three complexes exhibit in-field slow relaxation of the magnetization: 1 relaxes through an Orbach process at high temperatures [Ueff/kB = 60(1) K] evolving to quantum tunneling below 3 K [τQT = 0.05(1) s]; 2 exhibits a rapid Orbach-like process [τ0 = 8(6)⋅10–8 s and Ueff/kB = 10(2) K] and 3 shows a direct process [τ = 0.4(1) s].

Strong green up-conversion luminescence and optical thermometry of Ho3+/Yb3+ Co-doped AlN submicron towers

Rare-earth (RE) doped aluminum nitride (AlN) holds great promise for integrated optoelectronic devices. Here, the Ho and Yb co-doped AlN (AlN:Ho3+/Yb3+) submicron towers were prepared by a direct nitridation route. XRD, Raman, XPS and EDS studies showed successful doping of Ho and Yb ions into AlN. SEM images show that the submicron towers have an interesting layered structure by layer-by-layer stacking of hexagonal AlN nanosheets. Under excitation at 980 nm, AlN:Ho3+/Yb3+ submicron towers exhibit up-conversion (UC) luminescence at 540, 550, 659, and 762 nm, which are due to Ho3+/Yb3+ system from 5F4, 5S2→5I8, 5F5→5I8, and 5F4, 5S2→5I7 respectively. Based on the intensity ratio and decay lifetime of UC luminescence, the optical temperature sensing characteristics are investigated from 298 K to 548 K. The maximum relative sensitivities associated with the intensity ratio of I540, 550 and I659 and decay lifetime of 659 nm are as high as 2.73% K−1 and 0.43% K−1, respectively. This work broadens the optoelectronic properties of RE doped AlN.

Monolayer calibration of endofullerenes with x-ray absorption from implanted keV ion doses

X-ray absorption spectroscopy (XAS) has the highest sensitivity for chemical element detection on surfaces. With this approach, small amounts of lanthanide-containing endofullerene molecules (Ho3N@C80) have been measured by total electron yield at a low flux bending magnet beamline. The monolayer coverage is calibrated by extrapolating the signals of constant doses (3×1014 cm−2) of Ho ions implanted into SiO2 with energies between 2 and 115 keV. At room temperature, the Ho XAS spectra of the molecules and implanted ions indicate trivalent but not identical Ho ground states. Still, this approach demonstrates a way for calibration of small coverages of molecules containing open core-shell elements.

Investigation on doping behavior of Ho ions in Lu2SiO5 lattice by XRD Rietveld refinement and first-principles calculations

The effect of Ho doping on Lu2SiO5 lattice parameters and its occupation preference were investigated by experimentally and theoretically. A series of (Lu1-xHox)2SiO5 precursors were synthesized by a Sol-gel processing, the phase evolution behaviors were explored by XRD characterization after being calcined under temperatures ranging from 975 °C to 1300 °C. It was discovered that the crystallization temperature of synthetic precursors from amorphous to X1-(Lu1-xHox)2SiO5 phase was about 975 °C, and the temperatures of phase transformation from X1-(Lu1-xHox)2SiO5 to X2-(Lu1-xHox)2SiO5 varied from 1100–1300 °C. The defect formation energies of Ho substituted in X2- Lu2SiO5 were obtained by first-principles calculations, which indicated that the Ho3+ was prone to occupy the coordination polyhedral of [LuO7]. Furthermore, it was found that the introduction of Ho into X2- Lu2SiO5 caused the increasing of lattice parameters and the distortion of [LuO7] coordination polyhedron, which contributed to regulate and control the physical and chemical properties.

Calculations of the Binding-Energy Differences for Highly-Charged Ho and Dy Ions

The binding-energy differences for163Hoq+and163Dyq+ions with ionization degreesq=38, 39, and 40 are calculated. The calculations are performed using the large-scale relativistic configuration-interaction and relativistic coupled-clusters methods. The contributions from quantum-electrodynamics, nuclear-recoil, and frequency-dependent Breit-interaction effects are taken into account. The final uncertainty does not exceed 1 eV. Combining the obtained results with the binding-energy difference for neutral atoms calculated in [I.M.Savelyev, M.Y. Kaygorodov, Y.S. Kozhedub, I.I. Tupitsyn, and V.M. Shabaev, Phys. Rev. A105, 012806 (2022)], we get the secondary differences of the ion–atom binding energies. These values can be used to evaluate the amount of energy released in the electron capture process in163Hoatom (theQvalue), provided mass differences of highly charged ions163Hoq+and163Dyq+is known from experiment. TheQvalue is required by experiments on the determination of the absolute scale of the electron neutrino mass by studying the beta-decay process.

GLDA and ion exchangers: Unlocking sustainable solutions for recovery of rare earth elements

GLDA (tetrasodium salt of N,N-bis(carboxymethyl)-L-glutamic acid) was proposed as a complexing agent for rare earth elements. The formed complexes Ln(III)-GLDA were subjected to adsorption using twelve commercial ion exchangers of different types. Ion exchangers were characterized by describing their physicochemical properties using sieve analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The stability constants of the Ln(III)-GLDA complexes in the binary systems at different Ln(III):GLDA molar ratios were determined by the potentiometric method. The effects of different process parameters (Ln(III):GLDA molar ratio, initial solution pH, phase contact time, initial solution concentrations, and temperature) on the adsorption of La(III), Nd(III), and Ho(III) ions in the presence of GLDA were investigated by the static method in the single-component systems.Kinetic, equilibrium, and thermodynamic parameters were calculated. The highest adsorption capacities were obtained for the Purolite S957 ion exchanger (139.57 mg/g for the La(III)-GLDA complexes, 152.72 mg/g for the Nd(III)-GLDA complexes, and 151.29 mg/g for the Ho(III)-GLDA complexes), Lewatit Monoplus SP112 ion exchanger (155.49 mg/g for the La(III)-GLDA complexes, 150.23 mg/g for the Nd(III)-GLDA complexes, and 132.77 mg/g for the Ho(III)-GLDA complexes). The desorption process was performed to regenerate the ion exchangers by applying hydrochloric and nitric(V) acids at concentrations of 0.5, 1, and 2 M. In addition, for La(III)-GLDA complexes, experiments were performed in the column systems.

Photochromic ceramics for multimode detection of UV-VIS radiation dose

Electromagnetic radiation in the ultraviolet-to-visible (UV-VIS) band is closely related to human life, and therefore, accurate measurement of UV-VIS radiation dose is essential. However, there are disadvantages to existing radiation dose equipment: it is cumbersome to operate, takes time to analyze, and lacks multimodal measurements. In this study, a photochromic ceramic with rare earth ions Ho3+ and Yb3+ co-doped Ca2SnO4 host was developed. It produces rapid color switching between light yellow and black under UV and VIS radiation. The XPS and EPR results indicate that oxygen vacancies are important in coloring. Based on the photochromic effect, the intensity of down and up-conversion luminescence can be regulated. The maximum regulation rate is 95 %, higher than most photochromic materials of the same type. A multimode UV-VIS radiation detection method is proposed based on photochromism, down-conversion, and up-conversion luminescence light intensity modulation. The results show that the ceramics respond to a wide spectral range of electromagnetic radiation from UV-VIS with varying degrees, and the best response is to UVB (Ultraviolet Radiation B). A convenient scheme for on-site radiation dosimetry by colorimetry and changes in luminescence intensity was designed to verify the method's reliability. Stability tests have shown that these ceramics have good cyclic stability, making them an ideal detection material for accurate UV-VIS radiation dose detection.

Fluorescence study of Ho3+/Yb3+ ions codoped Bismuth-boro-tellurite glasses

Ho/Yb co-doped Bismuth boro-tellurite glasses were synthesized by conventional melt-quench methods. Thermal properties of the prepared samples were carried by differential scanning calorimetry. UV–VIS-IR absorption spectra were studied for the calculation of forbidden energy gap and refractive index of prepared glasses. For the study of photoluminescence samples were excited by 980 nm laser diode, intense green and red emissions were detected easily even by naked eyes. The observed intense red emission is thought to be caused by a combination of excited state absorptions between different levels of Ho ions and cooperative energy transfer upconversion from a pair of Yb donor ions to one Ho acceptor ion, in addition to the usual direct energy transfer process from Yb3+ to Ho3+.

Structure, optical transition analysis and magnetic study of lanthanide based metal-organic framework: holmium bi-tartrate trihydrate

This study presents the hydrothermal synthesis of holmium bi-tartrate trihydrate single crystals. The crystal structure and morphology were determined using single crystal x-ray analysis and field emission scanning electron microscopy, respectively. Fourier transform infrared spectroscopy was employed to identify the ligand phase. The thermal stability was assessed through differential scanning calorimetry. The effect of ligand on the incorporated paramagnetic center is discerned by reckoning the magnetic moment of the same. Judd-Ofelt theory was utilized to analyze optical transitions and calculate excited state properties. The complex exhibited violet and red emissions, attributed to ligand-based and metal-based luminescence , respectively. The absence of antenna effect was due to a significant energy gap between the resonance energy state, 5 S 2 of the Ho(III) ion and the triplet state of the coordinated tartrate ligand. The synthesized MOF's prolonged radiative lifetime holds promise for laser technologies and environmental monitoring applications.

Calculations of the Binding-Energy Differences for Highly-Charged Ho and Dy Ions

The binding-energy differences for ^{{163}}{text{H}}{{{text{o}}}^{{q + }}} and ^{{163}}{text{D}}{{{text{y}}}^{{q + }}} ions with ionization degrees q = 38, 39, and 40 are calculated. The calculations are performed using the large-scale relativistic configuration-interaction and relativistic coupled-clusters methods. The contributions from quantum-electrodynamics, nuclear-recoil, and frequency-dependent Breit-interaction effects are taken into account. The final uncertainty does not exceed 1 eV. Combining the obtained results with the binding-energy difference for neutral atoms calculated in [I.M. Savelyev, M.Y. Kaygorodov, Y.S. Kozhedub, I.I. Tupitsyn, and V.M. Shabaev, Phys. Rev. A 105, 012806 (2022)], we get the secondary differences of the ion–atom binding energies. These values can be used to evaluate the amount of energy released in the electron capture process in ^{{163}}{text{Ho}} atom (the Q value), provided mass differences of highly charged ions ^{{163}}{text{H}}{{{text{o}}}^{{q + }}} and ^{{163}}{text{D}}{{{text{y}}}^{{q + }}} is known from experiment. The Q value is required by experiments on the determination of the absolute scale of the electron neutrino mass by studying the beta-decay process.

Ho and Nd ion beam modifications of ZnO thin films

This work reports the influence of the annealing temperature on the structural and optical characteristics of ZnO films implanted with Ho+ and Nd+ ions. ZnO films have been synthesized in the form of arrays of highly oriented nanorods on silicon substrates by RF magnetron sputtering. Ion implantations led to an increase in the crystallinity level of the films. The temperature changes in the lattice parameters and sizes of ZnO nanocrystals in nanorods are presented. Threshold temperatures of bulk crystallization and the photoluminescent properties of nanorods were established. It is shown that the implanted elements are almost uniformly distributed throughout the thickness of the films and accumulate at the SiOx/Si interface during high-temperature annealing.

Ho-Ion-Polymer/Graphene Heterojunctions Toward Room-Temperature Ferromagnets.

Organic ferromagnetic materials offer great promise for spintronic devices, carbon-based chips, and quantum communications, but remain as a challenging issue due to their low saturation magnetization and/or unsustainable ferromagnetic properties. To date, magnetic ion polymers have displayed paramagnetism without exception at room-temperature. In this study, it is reported for the first time that, owing to the structural restriction and charge exchange of Ho ion by polymer/graphene π-π stacking heterojunctions, holmium ion polymer composites exhibited typical hysteresis lines of ferromagnetic materials at room temperature. The room-temperature ferromagnetic ion polymer composite presented the highest saturation magnetization value of 3.36 emu g-1 and unprecedented sustainable ferromagnetism, compared to reported room-temperature organic ferromagnetic materials. Accordingly, prepared ferromagnetic composites also achieved impressive wave absorption properties, with a maximum reflection loss of as much as -57.32dB and a broad absorption bandwidth of 5.05GHz. These findings may promote the development of room-temperature organic ferromagnetic materials.

Synthesis of Fluoro-Bridged Ho3+ and Gd3+ 1,3,5-Tris(4-carboxyphenyl)benzene Metal-Organic Frameworks from Perfluoroalkyl Substances.

A new fluoro-bridged rare-earth (RE) metal-organic framework consisting of 15-connected nonanuclear and 9-connected trinuclear clusters {[RE9-(μ3-F)14(H2O)6][RE3(μ3-F)(H2O)3](HCO2)3-(BTB)6}·(solvent)x 2 (RE = Ho3+ and Gd3+) was synthesized through the transformation of a dimeric complex formulated as bis(2,2'-bipyridine)tetrakis(μ-2-fluorobenzoato-O,O')-bis(2-fluorobenzoato)diRE(III) 1 with the bridging linker 1,3,5-tris(4-carboxyphenyl)benzene (H3BTB). The rare-earth metal ions Ho3+ and Gd3+ were also found to remove fluorine from other organo-fluorine compounds such as perfluorohexanoic acid (PFHxA) and perfluorooctanoic acid (PFOA), resulting in the new fluoro-bridged RE-MOFs.

Iminodisuccinic acid (IDHA) as an effective biodegradable complexing agent in the adsorption process of La(III), Nd(III) and Ho(III) ions

Environmental pollution and the continued depletion of many deposits have made the recycling of used materials an urgent need. An important aspect of this topic is the development of alternative compounds with a more favourable environmental profile compared to those currently in use. Indeed, when designing such processes, the negative human impact on the environment should be mitigated as much as possible. This paper presents the results of a study on the application of biodegradable complexing agent iminodisuccinic acid (IDHA) for the recovery of La(III), Nd(III) and Ho(III) by adsorption (single-component systems, static and dynamic methods) using various types of ion exchangers. The results obtained allow to determine the optimal process conditions and show that the chelating ion exchanger Purolite S957 has the highest adsorption capacity related to the La(III) complexes (142.29 mg/g), while the Nd(III) and Ho(III) complexes adsorb with the highest efficiency (161.04 mg/g for Nd(III) and 201.74 mg/g for Ho(III)) in the cation exchanger Lewatit SP112. According to the desorption studies the adsorbents are characterized by a large regeneration capability. This paper also presents the characterization of the physicochemical properties of the applied ion exchangers and the analysis of the binary systems (Ln(III)-IDHA) to determine the overall stability constants of the complexes using the potentiometric methods. Biodegradable IDHA was used to this aim.

Transformation of 5I8→5F5 Ho absorption band in Ho0.75Nd0.25Fe3(BO3)4 crystal during spin-reorientation transition

Polarized absorption spectra of crystal Ho0.75Nd0.25Fe3(BO3)4 in the region of the 5I8→5F5 absorption band of Ho ions were investigated depending on temperature in the range of 5–20 K. Absorption spectra are decomposed into components of the Lorentz form. The spin-reorientation phase transition was detected at 6.9 K. The observed line position shifts during the reorientation transition were different for different lines, which indicated different local magnetic anisotropy of the Ho ion in its excited states. Significant changes in absorption line intensities as a function of temperature were observed during the reorientation transition and above. These were explained as a consequence of the change in even components of the local crystal field in excited states. These components mix the closely spaced 4f states. Distortion of local symmetry in the ground state was detected at one of the electron transitions.

Tunable Emission Wavelength and Chromaticity Electroluminescence Realized in Ho Doped ZnO Microspheres Heterojunction

Tunable white light sources have huge potential applications in the scope of intelligent lighting or high-quality display system, but it is still a challenge to tune the emission wavelength and chromaticity in a simple structure. Herein, the Ho3+ doped ZnO microsphere was bonded onto the p-GaN substrate to form a heterojunctional light-emitting diode. Through a combination of the light confinement effect in the ZnO microsphere and multilevel emission system in rare earth materials, the device demonstrates tunable electroluminescence (EL) both in wavelength and chromaticity. The device shows broadband emission peak at 400 nm with full width at half maximum (FWHM) of 34 nm under forward pulsed driven bias. While it shows a series of sharp emissions from rare earth ions Ho3+ with peaks at 427 nm, 492 nm, 567 nm, 592 nm and 654 nm and FWHM less than 1.3 nm under reverse pulsed driven bias. More meaningful, the wavelength and chromaticity can be controlled with duty cycle or the rate of forward and reverse driven bias under intelligent programmable alternating current (AC) driven. Finally, the gradient from blueviolet light to white light can be realized.