Influence Of La3 Research Articles

Influence of La3+ ions on the structural, elastic, optical, and radiation shielding properties of Cr2O3-Doped heavy metal glasses

This study investigates the effect of La³⁺ rare earth ions on the structural, elastic, optical, and radiation shielding features of heavy metal borate glass (B₂O₃-PbO) doped with Cr₂O₃. Density measurements and FT-IR spectra analysis revealed the role of La3+ ions as a network modifier, where successive additions of La2O3 content led to a gradual increase in the density and an increase in the non-bridging oxygen content resulting from the structural transformation between the BO4 and BO3 units. The significant improvement in the elastic modulus and microhardness factor moduli was confirmed by calculating the change in ultrasonic velocities through the glassy system. The structural modifications induced by La³⁺ ions narrowed the band gap and increased the Urbach energy, indicating higher disorder within the glass network. The linear refractive indices increased due to increased optical basicity and electronic polarization. Optical absorption results showed that Cr⁶⁺/Cr³⁺ ions occupy octahedral/tetrahedral sites, with the tendency for Cr³⁺ cations to occupy more octahedral sites with increasing La₂O₃ content. The produced samples showed a greenish-yellow color caused by the absorption band centered at ∼415 nm associated with the electronic transition ⁴A₂g(F)→2Eg(G). The ligand field effect highlighted the significance of La³⁺ cations in increasing the crystalline field intensity surrounding Cr³⁺ cations and reducing the nephelauxetic ratio, signifying enhanced covalent character between Cr³⁺ cations and neighboring ions. Moreover, the radiation shielding capabilities of the glassy system were analyzed and compared with standard shielding materials, confirming superior shielding performance in samples with the highest La₂O₃ content.

Influence of La3+ doping on the band gap mediated ultraviolet photoconductivity of spray pyrolyzed ZnO thin films

Influence of La3+ doping on the band gap mediated ultraviolet photoconductivity of spray pyrolyzed ZnO thin films

Influence of La3+-Co2+ substitution on X-band microwave absorption properties of Ba0.5Sr0.5Fe12O19 nanoparticles with insight into quarter wavelength phenomenon

The presented study aims to tune the microwave absorption properties by varying the chemical composition of Ba0.5Sr0.5Fe12O19 nanoparticles with Co–La substitution via the synthesis route of the sol-gel citrate precursor method. X-ray diffractograms (XRD) and Fourier Transformed Infrared Spectroscopy (FTIR) confirmed the formation of pure phase M-type hexagonal ferrite with varying lattice parameters. The permittivity measurements revealed increased dielectric losses, indicating good energy dissipation behavior. Enhancement of magnetic behavior resulted from the strengthened exchange interactions between lattice sites, leading to higher permeability values. Significant reflection losses were exhibited by our synthesized samples with a maximum reflection loss of −42.08 dB at 4.62 GHz for x = 0.35 at an experimental thickness of 3 mm. The dependence of reflection loss peaks on matching thickness was analyzed using calculated thickness profiles, revealing their close agreement with simulated thickness. The study highlighted the potential of synthesized samples for electromagnetic signature reduction, in both commercial and military applications.

Influence of La3+ co-doping on the photoluminescence properties of YAG: Dy3+ electrospun light emitting nanofibers

Synthesizing Yttrium Aluminium Garnet (YAG) into nanoscale fibers significantly enhances its optical properties. These nanofibers exhibit excellent flexibility, lightweight nature, and high strength, making them highly suitable for smart clothing applications. Additionally, by doping rare earth ions into the YAG fibers, their luminescence properties can be further optimized, opening new possibilities for advanced smart clothing designs. In this paper, we present the successful fabrication of dysprosium (Dy) doped YAG nanofibers, lanthanum (La) doped YAG nanofibers, La co-doped Dy: YAG nanofibers with different concentration and investigate their photoluminescence properties. The photoluminescence excitation spectrum of the Dy3+-YAG nanofibers showed an intense peak centred at 350 nm due to absorption by Dy3+ ions and emits strong blue colour centred at 483 nm in emission spectrum, which is attributed to the 4F9/2 → 6H15/2 transition of Dy3+ions. The La3+-YAG nanofibers excited at 350 nm also showed an emission in blue region at 483 nm. Co-doping of La3+ ions in Dy3+-YAG nanofibers exhibited enhancement in the emission intensity significantly. In comparison with all as-synthesized nanofibers, specific concentration of Dy and La in YAG nanofibers would be the potential candidate for flexible light emitting devices.

Influence of La3+ doping on nebulizer spray pyrolysed In2S3 thin film for enhanced photodetector performance

In recent years, the photodetectors gained much attention due to their wide range of applications and fabrication of high-performance, cost-effective devices using environmentally friendly material is always challenging. In this work we report the fabrication of Lanthanum -doped indium sulfide thin films (In2S3:La) using a low-cost nebulizer spray pyrolysis method. La-doping concentration is varied from 0 to 5 wt% and the effect of doping on the properties of In2S3 thin films are investigated using X-ray diffraction (XRD), energy dispersive x-ray analysis (EDX), field emission scanning electron microscope (FESEM), UV–Vis spectroscopy, photoluminescence spectra. Incorporation of 3 wt% of La3+ in In2S3 lattice has substantially improved the crystallinity, surface morphology and optical properties of the thin films suitable for the device fabrication. Moderate doping of La3+ in the crystal lattice of β-In2S3 led to a red-shift in the absorption edge, which benefited utilization of wider light spectrum. Photodetectors are fabricated using In2S3:La (0–5 wt%) films and photodetector performance parameters are evaluated using I-V characteristics and current–time characterization. The In2S3 film with 3% La dopant concentration showed high photodetector performance with estimated detectivity (D*), photoresponsivity (R), and external quantum efficiency (EQE) of 1.11 × 1011 Jones, 5.05 × 10-1 AW−1, 118% respectively. For the same sample, the rise and fall time calculated from transient photo-response analysis is found to be 0.4 s and 0.3 s respectively. These optimally doped In2S3:La 3wt% thin film samples could be useful for the fabrication of photosensor based optoelectronic devices.

Impact of La3+ doping on temperature coefficient of resistivity and peak temperature of La x Ca0.89-xSr0.11MnO3 films prepared by sol-gel spin coating method

Herein, refined LaxCa0.89-xSr0.11MnO3 (LCSMO, x = 0.65, 0.68, 0.71 and 0.74) films were prepared through the sol-gel spin-coating. The influence of La3+ content on the structural properties of LCSMO films was investigated by X-ray diffraction and Atomic force microscope, demonstrating that LCSMO films can grow well on SrTiO3 (00l) substrate. Besides, X-ray photoemission spectroscopy verified the double exchange (DE) effect was weakened with La3+ dopant. The La3+ doping and interconnected grains boundaries (GBs) led to the weakening DE effect and GBs scattering, respectively. Due to superior GBs connectivity, the resistivity of LCSMO films was less than 7.1 × 10−4 Ω·cm at low temperature of 100 K. Importantly, it is an effective control method to keep the temperature (Tk) corresponding to temperature coefficient of resistivity (TCR) at room temperature with Sr2+ content as constant in LCSMO films. At x = 0.71, the peak TCR value was found to be 8.84%/K and corresponding Tk was 283.15 K. These results are beneficial for advanced application of uncooling infrared bolometer.

PHOTOCATALYTIC ACTIVITY OF MESOPOROUS TiO2 (ANATAS) IN THE REACTION OF HYDROGEN RELEASE FROM AQUEOUS-ETHANOLIC MIXTURE

Samples of mesoporous nanocrystalline titanium dioxide (anatase with a crystallite size of about 10 nm) were obtained by a modified sol-gel method in the presence of a template of dibenzo-18-crown-6 and small additives of surfactant (dodecylmethylethylammonium bromide) or ions of lanthanum (III) in butyl alcohol in combination with hydrothermal treatment at 175 °C for 24 hours followed by calcination in air at 500 °C for 4 hours. The photocatalytic activity of the obtained TiO2 samples was investigated in a model reaction of the photocatalytic release of H2 from an aqueous-ethanol mixture. It was found that in all cases the use of hydrothermal treatment significantly increases the photoactivity of the obtained sample, which in some cases is more than 3-4 times higher than the corresponding characteristic for commercial photocatalyst Evonik P25. The key effect of hydrothermal treatment on the increase of photoactivity of the samples is probably the consequence of a drastic increase in the treated samples of pore volume and diameter, as well as a decrease in the size of anatase crystallites. These changes (along with a significant increase in the specific surface area) are greater for samples obtained in the presence of La3+ ions. It is shown that samples of TiO2 microspheres obtained at the same concentrations of reagents in the reaction mixture show slightly higher photocatalytic activity than the corresponding lanthanum-stabilized samples of mesoporous TiO2 powders (micrometer-scale particles are not formed in the presence of lanthanum (III) ions). However, with an increasing concentration of reagents in the reaction mixture, the photocatalytic activity has the sample containing lanthanum. Probably, this can be explained by the high textural characteristics of the TiO2 sample in combination with the peculiarities of its morphology - the formation of secondary nanoparticles of agglomerated formations and the influence of La3+ ions. It is worth noting that the photocatalytic activity of TiO2 samples prepared in the presence of La3+ ions reduces as their specific surface area decreases.

The electrocaloric effect of Ba1-xLaxTi0.9Sn0.1O3 ceramics with excellent temperature stability near room temperature

The Ba1-xLaxTi0.9Sn0.1O3 ceramics (x = 0, 0.006, 0.007, 0.008) were prepared by the traditional solid-state reaction method. The influence of La3+ on the phase, dielectric properties, ferroelectric properties, and electrocaloric effect (ECE) was analyzed in detail. The results of refinement show that all ceramics are multiphase coexistence at room temperature, including the cubic phase, the tetragonal phase, and the orthogonal phase. With the increase of La3+, the polar phases decrease but the non-polar phase increases, which is the main reason for the decline in adiabatic temperature change (ΔT). The analysis of dielectric properties and ferroelectric properties demonstrate that the diffuse phase transition is strengthened by introducing La3+. It also means that polar nanoregions (PNRs) might be formed. Therefore, the temperature stability of the Ba1-xLaxTi0.9Sn0.1O3 ceramics in a wide temperature range near room temperature is improved. Simultaneously, the PNRs provide additional entropy to improve ECE. A higher ΔT = 0.88 K is obtained under 60 kV/cm for x = 0.007, which also possesses excellent temperature stability in the temperature range of 298 K–378 K. The doping of La3+ also improves the electric field threshold of the electrocaloric strength (ΔTmax/ΔE) and stabilizes the ΔTmax/ΔE under a higher electric field, which is conducive to improving ECE under a higher electric field and providing another possible solution for promoting the practical application of ECE.

Influence of La3+, Sm3+and Dy3+ dopants on ceria solid electrolytes for IT–SOFCs

The La3+, Sm3+ and Dy3+ triple doped ceria Ce1–x–y–zLaxSmyDyzO2-δ (x/y/z = 0.02, 0.04, 0.06, 0.08, and 0.10) ceramics were prepared successfully. Prepared ceramics were sintered using conventional sintering at 1300 °C and relative density values found to above 95%. Phase identification, micro-structure, thermal, as well as electrical studies of prepared ceramics were investigated using Powder X–ray Diffraction, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Micro-Raman, Impedance as well as Thermal Expansion characterizations. From this investigation, the ceramics with single-phased cubic structure, uniformly-distributed grains, high-density in microstructure, presence of compositional elements, and relative oxygen vacancies were confirmed in the compositions. The high electrical conductivity (0.027 S/cm at 550 °C) and low activation energy (0.82 eV) as well as matched thermal expansion coefficient of Ce0.82La0.06Sm0.06Dy0.06O2-δ (CLSD6) makes its possibility in intermediate temperature – solid oxide fuel cell applications.

Influence of La3+ ions doping on morphology and magnetic properties of Mg–Co ferrites

Influence of La3+ ions doping on morphology and magnetic properties of Mg–Co ferrites

Investigation of structure, morphology, photoluminescence, linear and third-order nonlinear optical properties of Sn1−xLaxO2 thin films for optical limiting applications

Transparent nano-crystalline thin films of Sn1−xLaxO2 (x = 0–0.1) were deposited on glass substrates using the cost-effective chemical spray pyrolysis method. The influence of La3+ concentration on the structural, morphological, linear and third-order nonlinear optical properties of the films were analysed. All the films possessed tetragonal crystalline structure, having a preferred (1 1 0) plane orientation irrespective of the doping content. Till a doping of 3 at%, the crystallite size showed a decreasing tendency. The fibrous morphology exhibited by the pure film got transformed into dense spherical microstructures at lower La doping levels. The films with lower doping content showed above 60% of transmittance in the visible wavelength region. The modification in the energy band gaps of the films were observed due to variations in the La concentration. The presence of various defects identified in the deposits by photoluminescence (PL) spectra analysis in the ultraviolet and visible region. Near white light emission was noticed in the films due to these defects. All the films exhibited third-order optical nonlinearity with an observed switching between reverse saturable absorption (RSA) and saturable absorption (SA). The films exhibited self-focussing and defocussing nature due to variation in the doping level. Sn0.94La0.06O2 film was identified as suitable for optical limiting application due to its least limiting threshold value. Hence, these spray pyrolyzed La doped films can be used in optical and nonlinear optical devices.

Phase pure synthesis of lanthanum doped bismuth ferrite nanostructures for the adsorption of doxorubicin

The improper disposal of pharmaceutical effluents, hospital sewage, wastes, and domestic drugs are the typical sources of emerging organic contamination (EOC). The untreated doxorubicin (DOX) effluent being released into the environment has harmful influence on human health. In this study, the lanthanum substituted bismuth ferrite nanoparticles with pure rhombohedral phase were prepared via facile co-precipitation technique, wherein the influence of La3+ ion substitution on structural, optical, and electrical properties of BiFeO3 (BFO) nanoparticles was investigated. Lanthanum content increment did not widely impact the structural properties but a systematic decrease in bandgap with increasing concentration of La3+ ion content was observed. DOX was treated with Bi1−xLaxFeO3 to investigate adsorption activity, where the kinetic modelling of isotherms and intraparticle diffusion showed that the adsorption of DOX followed the multi-layered heterogeneous adsorption mechanism. The BFO nanoparticles exhibited the highest adsorption efficiency of about 93% for DOX in the aqueous solution. The electrostatic interaction between DOX and BFO nanoparticles along with substantial diffusion at porous sites was the probable degradation mechanism of DOX. To assess the reusability merit, BFO were reused up to 4 times as an absorbent for DOX adsorption. Phase pure BFO can efficiently remove the DOX from aqueous medium and provide a cost-effective and eco-friendly solution to deal with EOC of water.

Lattice effects on the multiferroic characteristics of (La, Ho) co-substituted BiFeO3

The influence of La3+ and Ho3+ co-substitution on the structural, electrical and magnetic properties of rhombohedrally distorted polycrystalline BiFeO3 is reported. The presence of a tiny residual secondary phase of Bi2Fe4O9, Bi25FeO40 is evident in all the samples, while La doping suppresses the impurity phase and favors the grain growth (size of 1–2 µm) of the pristine compound. A fivefold increase in the dielectric constant (230 at 1 MHz) is achieved for the samples with the highest La content with a remarkable reduction in the dielectric loss. LaxHoyBi1-(x+y)FeO3 ceramics exhibit lossy ferroelectric loops and the magnitude of polarization reduces upon the co-substitution. The antiferromagnetic BiFeO3 transforms to ferromagnetic at low temperatures due to the annihilation of the cycloid-spin structure. The co-substitution effectively improved the magnetic properties. ‘Ho’ substitution helps in achieving the enhanced magnetization values while ‘La’ substitution helps in increasing the magnetic coercivity, HC. The variation of the HC with the temperature is interpreted by means of the two sublattice model.

Co-Doped Rare-Earth (La, Pr) and Co-Al Substituted M-Type Strontium Hexaferrite: Structural, Magnetic, and Mossbauer Spectroscopy Study

The present study investigates the influence of La3+ and Pr3+ doping on the structural, magnetic properties, and hyperfine fields of Sr0.7RE0.3Fe12-2x CoxAlxO19, (RE: La3+ and Pr3+, x = 0.0 - 0.8) hexaferrite compounds prepared via auto-combustion technique. The XRD analysis shows a linear decrease in a and c lattice and unit cell volume contraction with the content x. The room temperature magnetic study shows that for the Pr3+ doped Sr0.7Pr0.3Fe12-2x CoxAlxO19 (Pr3+-SrM), the magnetization value monotonically decreases while for La3+ doped Sr0.7La0.3Fe12-2xCoxAlxO19 (La3+-SrM) magnetization value shows a noticeable increase in magnetization value with x. The coercivity of the Pr3+-SrM compound was observed to decrease while that of the La3+-SrM compound showed a marked 40% increase at x = 0.2 (~5829 Oe) in comparison to undoped SrFe12O19 (~3918 Oe). A difference in Curie temperature was also observed, with Tc ~ 525°C at x = 0.4 for Pr3+-SrM and Tc = 505°C for x = 0.4 for La3+-SrM compound. The observed differences in magnetic properties have been explained on the basis of the site occupancy of Co2+ and Al3+ in the presence of rare-earth ions. The presence of non-magnetic rare-earth ion, La3+, improved saturation magnetization, and coercivity and deemed suitable replacement for Sr2+. The hyperfine parameters namely quadrupole shift showed a decrease with the La3+ or Pr3+ doping independent of (Co2+-Al3+) ions doping. Overall, the Mossbauer analysis suggests that the (Co2+-Al3+) impurities prefer occupancy at 2a site.

Temperature-insensitive large electrocaloric effect near room temperature in La3+-doped lead magnesium niobate-lead titanate ceramics

The influence of La3+-doping on the electrocaloric effect (ECE) of the 0.75(Pb1-3x/2Lax)(Mg1/3Nb2/3)O3-0.25(Pb1-3x/2Lax)TiO3 (L-PMN-PT: x/75/25 x = 0.0–4.0 mol.%) ceramics was studied. With the increase of La3+-doping in these ceramics, the relaxor ferroelectric properties increase, while the average grain size, coercive field Ec and Curie temperature TC decrease. As a result, a maximum adiabatic temperature change ΔT as high as 0.68 K, measured by direct measurement method, was achieved under a lower electric field (E) intensity of 5 kV/mm at 383 K for samples with x = 2.0 mol.%. Besides the high ΔT value, the La3+-doping also leads to a temperature insensitivity of ΔT. The variation of ΔT is less than 0.15 K, or 28.3%, over a wide temperature range of 303–423 K. The La3+-doped PMN-PT ceramics, with large and temperature insensitive ΔT over a broad temperature range, is very helpful for practical application. The reduction of Ec and TC can be attributed to the suppression of long-range coupling between oxygen octahedrons due to the partial replacement of Pb2+ by La3+. The temperature insensitivity of ECE is attributed to the enhancement of relaxor ferroelectric properties.

Effects of La3+ on the enhancement NIR quantum cutting and UC emissions in Nd3+–Yb3+ co-doped transparent silicate glass-ceramics for solar cells

Near-infrared (NIR) quantum cutting (QC) and upconversion (UC) emission of Nd3+–Yb3+ co-doped in Si–Al–Ba–La transparent silicate glass-ceramics (SGC) were prepared. Influence of La3+ on the enhancement NIR QC and UC emission intensity of the co-doped Nd3+–Yb3+ in SGC were investigated. Thereby, NIR QC and UC emission intensity of the co-doped Nd3+–Yb3+ were increased strongly with increasing concentration of LaF3 from 5 up to 25 mol. %. The value of NIR QC emission intensity of the co-doped Nd3+–Yb3+ band centered at ~890, 947, 1071, 1339 and 1430 nm is maximized when the concentration of LaF3 reaches 25 mol. %. At the same time, with the increasing concentration of Yb3+, NIR QC emission intensity of the co-doped Nd3+–Yb3+ bands centered at ~890, 1071, 1339 and 1430 nm of Nd3+ and 947 nm of Yb3+ were gradually increased and reaches its maximum at 2.5 mol. % Yb3+, then decreased owing to the self-quenching effect. In addition, NIR QC mechanism and energy transfer (ET) processes between 2F5/2 → 2F7/2 transition of Yb3+ and transitions of Nd3+ are discussed.

Highly responsive and selective formaldehyde sensor based on La3+-doped barium stannate microtubes prepared by electrospinning

Abstract

Influence of La3+ and V5+ doping on the polarization and impedance behaviour of BaBi2Nb2O9 nano-ceramics prepared by chemical route

The effect after the incorporation of La3+ and V5+ on BaBi2Nb2O9 ceramics was investigated by the analysis of structural and electrical studies. The materials are synthesized using chemical precursor solution decomposition method. Single orthorhombic phase was established after calcined the precursor mass at 700 °C for 3 h studied using X-ray diffraction study. The morphology of the samples was studied using scanning electron micrograph and transmission electron micrograph. The Curie temperature was increased with increasing substitution. High relaxation behaviour was observed during impedance spectroscopy study. For higher substitution both grain and grain boundary conductivity appears in the samples. The dc activation energy was in the range of 1.13–1.43 eV which are lower than the relaxation activation energy. The polarization of all the samples increases with increasing electric field. BBLNV0.5 showed the highest energy efficiency about 86%.

Structural, magnetic and dielectric study of La3+ substituted Cu0.8Cd0.2Fe2O4 ferrite nanoparticles synthesized by the co-precipitation method

In this paper, a series of Cu-Cd-La nanostructured ferrites having composition Cu0.8Cd0.2Fe2-yLayO4 (y = 0.000–0.075) was synthesized by co-precipitation technique. The influence of La3+ doping on the structural, magnetic and dielectric properties of Cu-Cd ferrite nanoparticles was studied by XRD, FTIR, VSM and Dielectric measurements. Single-phase spinel structure of Cu0.8Cd0.2Fe2-yLayO4 ferrite nanoparticles is confirmed by the x-ray diffraction measurements. It is found that crystalline size increases up to doping concentration y = 0.015 and then decreases for higher concentration of La3+ contents in Cu-Cd ferrites. Increase in lattice constant is attributed to larger atomic radius of La3+ as compared to Fe3+ ion and decrease in lattice constant is attributed to the higher La3+ concentration that is linked with the appearance of grain boundaries. FTIR spectra reveal two bands (ʋ1 = 554.18 cm−1 ʋ2 = 483.49 cm−1) that corresponds to tetrahedral and octahedral sites, respectively, in all the prepared Cu-Cd ferrites. VSM measurements showed that the Coercivity and Saturation magnetization deceases with the concentration of La3+ ions. Dielectric parameters tend to decrease at higher frequency and a maximum is observed at a frequency 1.5 × 109 Hz. Dielectric constant, dielectric loss and dielectric loss tangent were calculated as a function of frequency and explained on the basis of Koop's theory. AC conductivity is found to increase with the frequency but at higher frequencies, ac conductivity start to decreases.

Influence of La3+ ion doping on physical properties of magnesium nanoferrites for microwave absorption application

Lanthanum (La3+ ions) doped magnesium ferrite nanoparticles i.e. MgLaxFe2−xO4 (x = 0, 0.05, 0.075, 0.1, 0.125) have been prepared using sol-gel technique. These as-prepared nanomagnetic particles were characterized by using X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), High resolution field emission scanning electron microscopy (HRFESEM) with energy dispersive spectroscopy (EDS), Transmission electron microscopy (TEM) and Vibrating sample magnetometer (VSM) techniques. X-ray diffraction analysis reveal that the samples are single phase cubic spinel crystals with size 12–15 nm. Lattice parameter increases with the increase in La3+ ion concentration. The induced strain calculated from Williamson-Hall plots shows that strain decreases from x = 0.0 to x = 0.075 and then increases from x = 0.1 to x = 0.125. FTIR spectra show that FeO stretching vibration peaks of octahedral (FeO6) and tetrahedral (FeO4) group broadness increases with lanthanum content due to gradual decrease in the grain size. These variations are attributed to lattice deformation induced by interparticle interactions, cation distribution, and La3+ ions concentration in the spinel structured samples. SEM micrographs revealed the existence of superfine particles and agglomerated patterns for higher La3+ ion content. The average particle size obtained from TEM images are in close agreement with the crystallite size calculated from the XRD patterns. The magnetic studies exhibited the saturation magnetization, retentivity, anisotropy constant and magnetic moment of the particles decrease with increasing La3+ ions concentration indicating the superparamagnetic nature of lanthanum doped magnesium ferrite samples.