Structural characterization, stability, and cytocompatibility study of chitosan BaTiO3@ZnO:Er heterostructures.

New imaging agents are required in cancer diagnosis to enhance the diagnostic accuracy, classification, and therapeutic management of tumors. Nanomaterials have emerged as a promising alternative to developing new nanostructures with imaging applications. In this study, a heterostructure based on barium titanate (BT), zinc oxide (ZnO), and erbium (Er) was prepared and coated with Chitosan (CS) to investigate their stability and compatibility with biological systems. The structure, particle morphology, luminescence properties, stability, and cytotoxicity of different nanoparticles (NPs) were assessed. The results demonstrated the formation of a [BT@ZnO:Er]-CS heterostructure, which is consistent with the relative intensities and positions of peaks in the X-ray diffraction (XRD) with an average crystallite size of ~76 nm. The electrokinetic measurement results indicate that the coated NPs are the most stable and have an average size close to 200 nm when the pH is between 3 and 5. Finally, we presented a cytotoxicity study of naked and CS-coated NPs. The results indicate that naked NPs exhibit varying cellular toxicity, as indicated by decreased cell viability, morphological changes, and an increase in an apoptotic marker. The CS-coated NPs prevented the cytotoxic effect of the naked NPs, demonstrating the significance of CS as a stabilizing agent.

Highly Sensitive Acetone Gas Sensors Based on Erbium-Doped Bismuth Ferrite Nanoparticles.

The acetone-sensing performance of BiFeO3 is related to structural phase transformation, morphology and band gap energy which can be modulated by rare-earth ions doping. In this work, Bi1-xErxFeO3 nanoparticles with different amounts of Er doping were synthesized via the sol-gel method. The mechanism of Er doping on acetone-sensing performance of Bi1-xErxFeO3 (x = 0, 0.05, 0.1 and 0.2) sensors was the focus of the research. The optimal working temperature of Bi0.9Er0.1FeO3 (300 °C) was decreased by 60 °C compared to BiFeO3 (360 °C). The Bi0.9Er0.1FeO3 sample demonstrated the optimal response to 100 ppm acetone (43.2), which was 4.8 times that of pure BFO at 300 °C. The primary reason, which enhances the acetone-sensing performance, could be the phase transformation induced by Er doping. The lattice distortions induced by phase transformation are favorable to increasing the carrier concentration and mobility, which will bring more changes to the hole-accumulation layer. Thus, the acetone-sensing performance of Bi0.9Er0.1FeO3 was improved.

Fabrication of PbO2 Electrodes with Different Doses of Er Doping for Sulfonamides Degradation.

In the present study, PbO2 electrodes, doped with different doses of Er (0%, 0.5%, 1%, 2%, and 4%), were fabricated and characterized. Surface morphology characterization by SEM-EDS and XRD showed that Er was successfully doped into the PbO2 catalyst layer and the particle size of Er-PbO2 was reduced significantly. Electrochemical oxidation of sulfamerazine (SMR) in the Er-PbO2 anode system obeyed te pseudo first-order kinetic model with the order of 2% Er-PbO2 > 4% Er-PbO2 > 1% Er-PbO2 > 0.5% Er-PbO2 > 0% PbO2. For 2% Er-PbO2, kSMR was 1.39 h-1, which was only 0.93 h-1 for 0% PbO2. Effects of different operational parameters on SMR degradation in 2% Er-PbO2 anode system were investigated, including the initial pH of the electrolyte and current density. Under the situation of an initial pH of 3, a current density of 30 mA·cm-2, a concentration of SMR 30 mg L-1, and 0.2 M Na2SO4 used as supporting electrolyte, SMR was totally removed in 3 h, and COD mineralization efficiency was achieved 71.3% after 6 h electrolysis. Furthermore, the degradation pathway of SMR was proposed as combining the active sites identification by density functional calculation (DFT) and intermediates detection by LC-MS. Results showed that Er-PbO2 has great potential for antibiotic wastewater treatment in practical applications.

Luminescence Properties and Judd-Ofelt Analysis of Various ErF3 Concentration-Doped BaF2 Crystals.

The influence of erbium ion concentration on the optical properties of BaF2:ErF3 crystals was investigated. Four ErF3 concentration (0.05, 0.08, 0.15 and 0.5 mol% ErF3)-doped BaF2 crystals were obtained using the Bridgman technique. Room temperature optical absorption in the 250-850 nm spectral range was measured, and the photoluminescence (PL) and decay times were also investigated. The Judd-Ofelt (JO) approximation was used, taking into account four absorption peaks (at 377, 519, 653 and 802 nm). The JO intensity parameters, Ωt (t = 2, 4, 6), were calculated. The influence of the ErF3 concentration on the JO parameters, branching ratio, radiative transition probability and radiative lifetime were studied. The obtained results were compared with measured values and with those reported in the literature. Under excitation at 380 nm, the well-known green (539 nm) and red (668 nm) emissions were obtained. The calculated and experimental radiative lifetimes were in millisecond range for green and red emissions. The intensity of the PL spectra varied with the Er3+ ion concentration. The emission intensity increased linearly or exponentially, depending on the ErF3 concentration. Under excitation at 290 nm, separate to the green and red emissions, a new UV emission band (at 321 nm) was obtained. Other research has not reported the UV emission or the influence of ErF3 concentration on emission behavior.

Enhanced Cycling Stability through Erbium Doping of LiMn2O4 Cathode Material Synthesized by Sol-Gel Technique.

In this work, LiMn2-xErxO4 (x ≤ 0.05) samples were obtained by sol-gel processing with erbium nitrate as the erbium source. XRD measurements showed that the Er-doping had no substantial impact on the crystalline structure of the sample. The optimal LiMn1.97Er0.03O4 sample exhibited an intrinsic spinel structure and a narrow particle size distribution. The introduction of Er3+ ions reduced the content of Mn3+ ions, which seemed to efficiently suppress the Jahn⁻Teller distortion. Moreover, the decreased lattice parameters suggested that a more stable spinel structure was obtained, because the Er3+ ions in a ErO6 octahedra have stronger bonding energy (615 kJ/mol) than that of the Mn3+ ions in a MnO6 octahedra (402 kJ/mol). The present results suggest that the excellent cycling life of the optimal LiMn1.97Er0.03O4 sample is because of the inhibition of the Jahn-Teller distortion and the improvement of the structural stability. When cycled at 0.5 C, the optimal LiMn1.97Er0.03O4 sample exhibited a high initial capacity of 130.2 mAh g-1 with an excellent retention of 95.2% after 100 cycles. More significantly, this sample showed 83.1 mAh g-1 at 10 C, while the undoped sample showed a much lower capacity. Additionally, when cycled at 55 °C, a satisfactory retention of 91.4% could be achieved at 0.5 C after 100 cycles with a first reversible capacity of 130.1 mAh g-1.

Er-Doped LiNi0.5Mn1.5O4 Cathode Material with Enhanced Cycling Stability for Lithium-Ion Batteries.

The Er-doped LiNi0.5Mn1.5O4 (LiNi0.495Mn1.495Er0.01O4) sample was successfully prepared by citric acid-assisted sol-gel method with erbium oxide as an erbium source for the first time. Compared with the undoped sample, the Er-doped LiNi0.5Mn1.5O4 sample maintained the basic spinel structure, suggesting that the substitution of Er3+ ions for partial nickel and manganese ions did not change the intrinsic structure of LiNi0.5Mn1.5O4. Moreover, the Er-doped LiNi0.5Mn1.5O4 sample showed better size distribution and regular octahedral morphology. Electrochemical measurements indicated that the Er-doping could have a positive impact on the electrochemical properties. When cycled at 0.5 C, the Er-doped LiNi0.5Mn1.5O4 sample exhibited an initial discharge capacity of 120.6 mAh·g-1, and the capacity retention of this sample reached up to 92.9% after 100 cycles. As the charge/discharge rate restored from 2.0 C to 0.2 C, the discharge capacity of this sample still exhibited 123.7 mAh·g-1 with excellent recovery rate. Since the bonding energy of Er-O (615 kJ·mol-1) was higher than that of Mn-O (402 kJ·mol -1) and Ni-O (392 kJ·mol-1), these outstanding performance could be attributed to the increased structure stability as well as the reduced aggregation behavior and small charge transfer resistance of the Er-doped LiNi0.5Mn1.5O4.

Improving the Photoelectric Characteristics of MoS2 Thin Films by Doping Rare Earth Element Erbium.

We investigated the surface morphologies, crystal structures, and optical characteristics of rare earth element erbium (Er)-doped MoS2 (Er: MoS2) thin films fabricated on Si substrates via chemical vapor deposition (CVD). The surface mopography, crystalline structure, light absorption property, and the photoelectronic characteristics of the Er: MoS2 films were studied. The results indicate that doping makes the crystallinity of MoS2 films better than that of the undoped film. Meanwhile, the electron mobility and conductivity of the Er-doped MoS2 films increase about one order of magnitude, and the current-voltage (I-V) and the photoelectric response characteristics of the Er:MoS2/Si heterojunction increase significantly. Moreover, Er-doped MoS2 films exhibit strong light absorption and photoluminescence in the visible light range at room temperature; the intensity is enhanced by about twice that of the undoped film. The results indicate that the doping of MoS2 with Er can significantly improve the photoelectric characteristics and can be used to fabricate highly efficient luminescence and optoelectronic devices.

Controlling the Er content of porous silicon using the doping current intensity.

The results of an investigation on the Er doping of porous silicon are presented. Electrochemical impedance spectroscopy, optical reflectivity, and spatially resolved energy dispersive spectroscopy (EDS) coupled to scanning electron microscopy measurements were used to investigate on the transient during the first stages of constant current Er doping. Depending on the applied current intensity, the voltage transient displays two very different behaviors, signature of two different chemical processes. The measurements show that, for equal transferred charge and identical porous silicon (PSi) layers, the applied current intensity also influences the final Er content. An interpretative model is proposed in order to describe the two distinct chemical processes. The results can be useful for a better control over the doping process. PACS: 81.05.Rm; 82.45.Rr.