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To study the synergistic lubricating effects of graphene oxide (GO) and lanthanum fluoride (LaF3), and find a new anti‐wear additive, oleic acid surface‐modified graphene oxide‐lanthanum fluoride (OA‐GO‐LaF3, OGL) composite nano‐additive was prepared by hydrothermal method by using oleic acid as the modifier. The morphology, structure, composition, element valence, thermal stability and tribological properties of nano additives were characterised by a series of modern characterisation methods. Results show that OGL has a higher degree of graphitization, smaller particle size, more homogeneous disperse, higher LaF3 load and stronger thermal stability than that of GL. The tribological properties of OGL which is modified by oleic acid are better than unmodified GL. Analysis of the friction mechanism shows that both OGL and GL can generate LaF3 physical adsorption films through adsorption during the friction process and tribochemical reactions film containing lanthanum compounds, carbon oxide compounds, and iron oxide compounds on the friction surface. These physical adsorption films and chemical reaction film can improve lubrication. [ABSTRACT FROM AUTHOR]

This study investigates the influence of La 2 O 3 addition on the structural, physical, and radiation shielding properties of basalt-based glasses. Incorporating varying concentrations of La 2 O 3 (0, 10, 20, 30 wt%) into basalt glasses, we aimed to evaluate the potential of La 2 O 3 in enhancing the material's effectiveness against gamma radiation. Utilizing Ba-133 point radioactive source and Ultra Ge detector, we measured the attenuation parameters in different photon energies (81, 160, 223, 276, 302, 356, and 383 keV). The glasses exhibited an amorphous structure, as confirmed by XRD analysis, with density values ranging from 2.72 to 3.305 g/cm³, increasing with La 2 O 3 content. The microstructural analysis indicated that La3+ ions predominantly integrate into the glass matrix, enhancing the structural integrity without forming separate phase regions. Our findings demonstrate a significant improvement in radiation protection parameters, including mass attenuation coefficients and half-value layers, with higher La 2 O 3 concentrations. These outcomes were also supported by the data obtained for Z eff and EBF values of G1-G4 glasses. The mechanical properties of the glasses were also investigated with the Makishima-Mackenzie model and it was observed that the elastic moduli were also affected by the addition of La 2 O 3. The enhancements observed with La 2 O 3 additions suggest promising avenues for developing advanced shielding materials, combining the inherent advantages of basalt glasses with the high atomic weight and electron density of lanthanum compounds. [ABSTRACT FROM AUTHOR]

Coordination compounds of lanthanum with carbacylamidophosphate - N,N'-tetraethyl-N''-(trichloroacetyl)phosphortriamide (HL) and 2,2'-bipyridine (bipy) of composition LaLbipy2(NO3)2 and LaL3bipy were synthesized and studied by means of X-ray, thermal gravimetric analyses, IR, and NMR spectroscopy. It was established that all the ligands in the complexes are coordinated towards lanthanum in bidentate manner. Coordination number of central ion equals ten and eight for LaLbipy2(NO3)2 and LaL3bipy, respectively. Coordination polyhedron of LaIII ion has distorted geometry between bicapped square antiprism and sphenocorona in LaLbipy2(NO3)2 and between square antiprism and triangular dodecahedron in LaL3bipy. The bonds lengths La-O and La-N are commensurate in the synthesized complexes. The both structures are characterized by the presence of numerous intermolecular interactions, which have been analyzed using Hirshfeld surface tool. A feature of the complex LaLbipy2(NO3)2 is the presence of two crystallographically independent molecules in crystal. The compounds LaLbipy2(NO3)2 and LaL3bipy are thermally stable to 175°C and 165°C, respectively. A feature of the tris-complex LaL3bipy is the presence of a phase transition at a temperature of 96°C. [ABSTRACT FROM AUTHOR]

The prototype high-entropy oxide (HEO) Y0.2La0.2Ce0.2Pr0.2Sm0.2O2−δ represents a particularly complex class of HEOs with significant anion sublattice entropy. The system takes either a fluorite or bixbyite-type crystal structure, depending on synthesis kinetics and thermal history. Here, we synthesize bulk ceramics and epitaxial thin films of Y0.2La0.2Ce0.2Pr0.2Sm0.2O2−δ and use diffraction to explore crystal symmetry and phase. Thin films exhibit the high symmetry fluorite phase, while bulk ceramics adopt the lower symmetry bixbyite phase. The difference in chemical ordering and observed symmetry between vapor-deposited and reactively sintered specimens suggests that synthesis kinetics can influence accessible local atomic configurations, i.e., the high kinetic energy adatoms quench in a higher-effective temperature, and thus higher symmetry structure with more configurational entropy. More generally, this demonstration shows that recovered HEO specimens can exhibit appreciably different local configurations depending on synthesis kinetics, with potential ramifications on macroscopic physical properties. [ABSTRACT FROM AUTHOR]

The present study describes the synthesis of lanthanum and cerium oxide (La2O3 and CeO2) nanoparticles (NPs) based on eco-friendly approach using Ficus religiosa leaves extract. The synthesized NPs have been characterized using various analytical techniques, including UV-Visible and FT-IR spectroscopy, and PXRD. The surface morphology and shape of the NPs have been determined using advanced imaging techniques such as Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and High-Resolution Transmission Electron Microscope (HRTEM) revealing that the NPs possessed predominantly spherical and rod-like shapes. Additionally, the surface area covered by NPs has been calculated using BET analysis and it shows an increment from a value of 7.243 m² g-1 to 45.144 m² g-1 and peak pore volume increases from 0.0743 cm³ g-1u to 0.1904 cm³ g-1. The antibacterial activity of NPs has been evaluated against Gram-positive and Gram-negative bacteria showing significant activity. Finally, the hemolytic and antioxidant activity of NPs have been assessed and have demonstrated their efficacy suggesting their potential applications. [ABSTRACT FROM AUTHOR]

In the present work, we have demonstrated a highly sensitive H2 gas sensor using a lanthanum doped ZnO (La_ZnO) thin film operated at 300 °C. Also, a p-type to n-type carrier reversal activity is revealed in the presence of H2 gas species, which predominantly depends on the operating temperature and doping concentration of lanthanum. Pure and La_ZnO (1–10 at. %) thin films were successfully synthesized using a sol-gel route, where a 5 at. % lanthanum doped ZnO thin film shows an outstanding H2 gas sensitivity (400%) among all other samples with an optimized temperature of 300 °C. Moreover, this sensor actively responds to a wide H2 gas concentration (10–500 ppm) with a sensitivity of 0.9 (∼n). Additionally, H2 gas sensing selectivity and mixed gas sensing performance were investigated in the presence of CO and CO2 gas species at optimized temperature (300 °C). Results show that the pure and 1–3 at. % La_ZnO thin films exhibited n-type H2 gas sensing, while p-type sensing behavior was observed for 5% and 10% La_ZnO thin films at 300 °C. It is further observed that O− species are extremely active to CO gas species operating at a high operating temperature (>250 °C). Therefore, despite the emerging p-type behavior of the sensor, the ejected electrons are expected to dominantly reduce the sensor resistance in the presence of CO gas species at 350 °C. The improvement of H2 sensing is further interrelated with the defect levels using Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Due to the specific affinity of lanthanum (La) toward phosphate over a wide pH range, La compounds such as lanthanum oxide (LO), lanthanum hydroxide (LH), and lanthanum carbonate (LC) have been integrated into various La-based adsorbents in recent years. In order to evaluate the differences among LO, LH, and LC in terms of phosphate removal performance (adsorption capacity, pH-dependent behavior, and selectivity), stability (La leaching), and reusability, data from the literature are consolidated. Furthermore, key properties of the respective compounds such as solubility and speciation are examined to identify possible underlying reasons. LC exhibits superior adsorption capacity and a wider optimum pH range for phosphate binding and lower La leaching, but reusability data of the various compounds remain inconclusive. Based on their superior performance and stability in laboratory studies, LC may have greater lifespan and can serve as a viable alternative to LO and LH for future studies on phosphate removal in order to maximize phosphate removal efficiency while simultaneously reducing secondary pollution. To further develop La-based adsorbents for phosphate removal and recovery, direct comparisons are needed among La compounds using more complex matrices such as wastewater and river water. Furthermore, the role of crystal structure in the phosphate removal performance of different compounds must be carefully assessed. Finally, to evaluate the feasibility of practical application and understand the effects of continuous flow operation on phosphate removal and recovery efficiency, more pilot-scale studies involving La-based adsorbents should be conducted. Performance, stability, and reusability of different La compounds are crucial to the practicability of La-based adsorbents for phosphate removal along with addressing key challenges associated with real-world usage. The simultaneous incorporation of other metals presents a possible way to improve on the inherent properties of La-based adsorbents to enable them to better address these challenges. [ABSTRACT FROM AUTHOR]

In the model manganese perovskites La1−xCaxMnO3, several important phenomena have been observed, including ferromagnetic metallic/insulating states, colossal magnetoresistance effects, and charge- and orbital-ordered states. In the past, only compounds with x = 1/2, 2/3 and 3/4 and an insulating ground/antiferromagnetic state have been studied. To fully understand the crystal and electronic structures of these materials, it is important to study compounds with doping levels in the range of 0.5 < x < 2/3. Here we study the crystal structure in a series of compounds with 0.5 < x ≤ 0.6 using ultrahigh-resolution synchrotron X-ray diffraction. The experimental results reveal that all compounds undergo a structural transition at T < TCO(x) ≈ 200 − 220 K with the concomitant emergence of superlattice Bragg peaks, which can be indexed assuming a superstructure with a modulation propagation vector, τ. At the base temperature of 5 K, the modulation vector of the superstructure τ = [τa, 0, 0] is parallel to the a-axis, with τa varying linearly with x, as τa ≈ 1 − x. Our results may aid attempts to understand more deeply phenomena related to spin, charge, and orbital ordering, as well as colossal magnetoresistance and symmetry breaking and emergent order in quantum states. Doped lanthanum manganite compounds exhibit a range of conducting, electronic and magnetic phases, and, in the case of the Ca-doped series, a phase transition from a ferromagnetic metal to an antiferromagnetic insulator occurs. Here, the authors use ultrahigh-resolution synchrotron X-ray diffraction to track the complex structural behavior of La1−xCaxMnO3 below the charge-ordering temperatures. [ABSTRACT FROM AUTHOR]

Background. There is no information in the literature about the synthesis of complex compounds of rare earth elements with 2-aminobenzimidazole and salicylic acid and their properties. This work is aimed at a systematic study of the synthesis, structure and properties of previously unknown complex compounds of some rare earth elements with 2-aminobenzimidazole and salicylic acid. Purpose. Development of a procedure for the synthesis of new mixed-ligand complex compounds of lanthanum (III) and cerium (III) with salicylic acid (HSal) and 2-aminobenzimidazole (ABI). Study of the composition and structure of the synthesized complex compounds by modern physicochemical methods. Methodology. Quantum chemical calculations, IR spectroscopy, elemental, thermogravimetric, SEMEDX, fluorescence analyzes. Originality. Mixed ligand complexes of lanthanum and cerium (III) with 2-aminobenzimidazole (ABI) and salicylic acid (HSal) were synthesized for the first time. Findings. Competing donor centers, electronic and geometric structures of the ligand molecule were studied by quantum-chemical calculation method. The composition and structure of the synthesized new complex compounds of lanthanides was determined by quantum-chemical, IR-spectroscopic, thermogravimetric, fluorescent analysis and SEM-EDX. [ABSTRACT FROM AUTHOR]

A series of LaF3:Ce3+ phosphors for application in photodynamic therapy are synthesized using a one-stage solvothermal synthesis. The synthesis conditions; type and quantity of stabilizer; concentration of activator providing the maximum intensity of UV- and X-ray-excited luminescence; lowest size; and highest colloidal stability of the phosphor nanoparticles are found. As a result of this study, the following parameters are determined using cerium content 5% mol. ethanol as the reaction medium for the solvothermal synthesis and polyvinylpyrrolidone as the stabilizer at an optimized amount. [ABSTRACT FROM AUTHOR]

We report on the thermoelectric properties of strained, highly-oriented, lightly-doped La1–xSrxCoO3 thin films, grown on MgO (100) substrates by pulsed laser deposition. The large lattice mismatch (∼9%), along with the different thermal expansion coefficients, between La1–xSrxCoO3 and MgO, result in the incoherent growth of thin films and the generation of a tensile thermal strain (∼1%). Room temperature resistivity values of the films are similar to those of bulk samples, while the temperature dependence of resistivity of the films does not seem to be affected by the thermal strain. The Seebeck coefficient values of all investigated films are positive but lower than those of their bulk counterparts, throughout the measured temperature range. The lower values of the films' Seebeck coefficient are attributed to the stabilization of mixed Co spin state configuration, which is induced by the thermal strain. As a result of the reduced Seebeck coefficient values, the thermoelectric power factor is suppressed, suggesting that the tensile thermal strain does not favor the thermoelectric behavior of the La1–xSrxCoO3. [ABSTRACT FROM AUTHOR]

LaSb2 has a layered crystal structure along the c-axis with ∼2% difference between the in-plane orthorombic a and b axes. Here, we report on the thermal conductivity, electrical resistivity, and Seebeck coefficient from 10 to 300 K as well as the magnetoresistance at 10 K. Using the van der Pauw technique on single crystal samples, the in-plane electrical resistivity tensor has been measured and it is found to be isotropic. An anisotropic crystal structure may have isotropic properties, but in the present case, the isotropic nature stems from crystal imperfection. Single crystal X-ray diffraction provides evidence of a mixing of the in-plane a- and b-directions leading to observed diffraction intensity where systematic absences are expected. Whether the underlying structural mechanism is twinning or stacking faults is unknown, but it could be the origin of the previously observed charge density wave states, and it may also explain the high unsaturating linear magnetoresistance reported here. At ambient conditions, LaSb2 is found to be stable in air, with no sign of bulk degradation after 5 years of storage; however, some change is observed in the amorphous background scattering. [ABSTRACT FROM AUTHOR]

We systematically investigate the thermoelectric properties of lanthanum phosphide (LaP) using first-principles calculations together with the Boltzmann transport theory. The dynamic stability of LaP is confirmed based on phonon dispersion. The different atomic masses of La and P atoms lead to an acoustic-optical bandgap that prohibits scattering between acoustic and optical phonon modes. The lattice thermal conductivity κ l is 3.19 W/mK at room temperature, which is less than that of LaAs because of the smaller group velocities and the larger Grüneisen parameter. The calculated phonon-mode contribution to κ l , scattering rate, and mean free path may provide significant guidance to further theoretical and experimental research. The power factor reaches 0.012 W m−1 K−2 at a carrier concentration of 1.05 × 10 20 c m − 3 , which is comparable to the power factor of the typical thermoelectric material Bi2Te3. This reasonable power factor and thermal conductivity suggest that LaP is a promising thermoelectric material. The dependence of the figure of merit ZT on carrier concentration n and temperature T indicates that a high ZT can be obtained by increasing the temperature and tuning the carrier concentration. [ABSTRACT FROM AUTHOR]

LaSb2 has a layered crystal structure along the c-axis with ∼2% difference between the in-plane orthorombic a and b axes. Here, we report on the thermal conductivity, electrical resistivity, and Seebeck coefficient from 10 to 300 K as well as the magnetoresistance at 10 K. Using the van der Pauw technique on single crystal samples, the in-plane electrical resistivity tensor has been measured and it is found to be isotropic. An anisotropic crystal structure may have isotropic properties, but in the present case, the isotropic nature stems from crystal imperfection. Single crystal X-ray diffraction provides evidence of a mixing of the in-plane a- and b-directions leading to observed diffraction intensity where systematic absences are expected. Whether the underlying structural mechanism is twinning or stacking faults is unknown, but it could be the origin of the previously observed charge density wave states, and it may also explain the high unsaturating linear magnetoresistance reported here. At ambient conditions, LaSb2 is found to be stable in air, with no sign of bulk degradation after 5 years of storage; however, some change is observed in the amorphous background scattering. [ABSTRACT FROM AUTHOR]

(Sr 0.95 La 0.05) 0.95 □ 0.05 TiO 3 ceramics were prepared by solid state reaction and sintered by spark plasma sintering at different temperatures ranging from 1473 to 1873 K for 10 min. The thermoelectric properties show that sintering at temperatures higher than 1773 K allows reaching high thermoelectric properties similar to the ones obtained after annealing at high temperatures in H 2 / N 2 for several hours. The high temperature sintered samples exhibit highest power factor near room temperature, resulting in ZT values higher than 0.1. Therefore, the 10 min short SPS process at high temperatures described in this paper is an easy, cheap, fast, and one step route to obtain dense and efficient SrTiO 3 -based thermoelectric ceramics. However, SEM observations show that the samples are not pure perovskite phase but contain titanium oxide and lanthanum compound aggregates. [ABSTRACT FROM AUTHOR]

We experimentally investigated the photo-induced direct current (DC) drift of a lead lanthanum zirconate titanate (PLZT) Mach-Zehnder modulator with large optical input power. We clarify the mechanism by which short-term and long-term DC drifts arise and discuss each case of DC drift. We reveal that short-term DC drift can be reduced by adjusting the buffer-layer resistivity of the PLZT modulator. We also found that the impurity level of the buffer layer affects long-term DC drift. [ABSTRACT FROM AUTHOR]

Temperature is one of the key factor that affecting the electrical, physical, structural, and morphological properties as well as the crystallinity of the nanomaterials. The current study investigates the effect of annealing temperature on the structural and electrical properties of lanthanum oxide (La2O3) thick films. La2O3 thick films were prepared on a glass substrate using a conventional screen printing technique. In this work, T1 is an unannealed prepared film, whereas T2 and T3 are annealed in a muffle furnace for 3 hours at 350°C and 450°C, respectively. XRD technique was exploited to investigate the crystallization behavior of the films. It was found that the crystal structure of La2O3 thick films are pure hexagonal phase. The annealing temperatures were revealed to have influence on the crystallite sizes of the films. SEM and EDS was used to study the morphology and elemental analysis of the films respectively. The electrical properties of the films were explored by measuring resistivity, temperature coefficient of resistivity (TCR), and activation energy at lower and higher temperatures regions. The film annealed at 450°C has high resistivity, a high TCR, and small crystallite size. The thickness of the La2O3 thick films was also found to decrease as the annealing temperature increased. [ABSTRACT FROM AUTHOR]

Lanthanum manganite (LMO) thin films were deposited by co-sputtering La and Mn targets in an Ar and O2 gas mixture. The films were synthesized on silicon and fused silica substrates. The influences of thermal annealing on the structure, optical and electrical properties of LMO films were investigated. The results exhibited a correlation between these properties. In the amorphous state, an increase in annealing temperature improved the optical transmission and decreased the electrical capacitance. The beginning of crystallization at 600 °C was manifested by a strong increase in the capacitance and a decrease in the optical transmission. At higher annealing temperature, polycrystalline films were obtained with different optical and electrical characteristics. On the other hand, the annealed LMO films showed a photocurrent effect during exposure to a weak LED light. [ABSTRACT FROM AUTHOR]

The development of high-performance low-cost electroactive films for energy conversion and electronic device applications is a key goal of current advanced materials and condensed matter physics research. Here, using solution-based scalable chemical spray pyrolysis, high-quality electroactive lanthanum-doped zinc oxide (i.e., Zn 1-x La x O) thin films are grown on silicon substrates, and the impact of aliovalent lanthanum doping is investigated using a suite of microstructural, optical and nanoscale scanning probe microscopy techniques. The synthesized polycrystalline thin films show hexagonal wurtzite crystal structure with an increased unit cell volume, crystallite size, and conductivity with lanthanum doping up to 4 at.% beyond which the thin films (6 at.%), however, exhibit a change in dominant crystalline orientation from (101) to (002) plane. Concurrently, at this optimal dopant concentration of 4–6 at.%, the electromechanical performance is enhanced by about 20 %, and polarity-dependent nanoscale electronic transport behaviour is revealed. Our study, therefore, provides key insights into the impact of the rare earth aliovalent lanthanum dopant on the electroactive and electronic properties of low-cost, functional thin films for sustainable energy and sensing applications. • Fabrication of high-quality wurtzite structured lanthanum-doped zinc oxide (Zn1-xLaxO, x = 0 – 0.06) thin films. • Increase in conductivity with lanthanum doping to 4 at.%. • Electromechanical performance was enhanced by about 13–20 % at optimal dopant concentration of La 4–6 at.%. • Electronic transport modulation by nearly two orders of magnitude depending on the polarity of the nanocrystallite surfaces. [ABSTRACT FROM AUTHOR]

Rotations and distortions of oxygen octahedra in perovskites play a key role in determining their functional properties. Here, we investigate how octahedral rotations can couple from one material to another in La2/3Sr1/3MnO3/SrTiO3 epitaxial heterostructures by first principles density functional theory calculations, emphasizing the important differences between systems oriented perpendicular to the (111)- and (001)-facets. We find that the coupling length of out-of-phase octahedral rotations is independent of the crystalline facet, pointing toward a steric effect. However, the detailed octahedral structure across the interface is significantly different between the (111)- and (001)-orientations. For (001)-oriented interfaces, there is a clear difference whether the rotation axis in SrTiO3 is parallel or perpendicular to the interface plane, while for the (111)-interface, the different rotations' axes in SrTiO3 are symmetry equivalent. Finally, we show that octahedral coupling across the interface can be used to control the spatial distribution of the spin density. [ABSTRACT FROM AUTHOR]

We have investigated the electrical and dielectric properties of rare earth perovskites-type oxide (LaErO3 and LaHoO3) by using impedance spectroscopy, respectively, over a frequency and temperature range of [0.6 kHz–8MHz] and [673–973 K]. Both oxides crystallize in the orthorhombic structure but exhibit difference in lattice distortions. A correlation between structural properties and dielectric anisotropies is carried out. The analysis of Nyquist semicircles confirms the presence of bulk effects and non-Debye relaxation processes for both compounds. The activation energy, calculated using relaxation time and direct current conductivity models, was found to follow the Arrhenius law. The frequency dependence of alternative current conductivity is described by Jonscher’s universal power law and shows that the conduction mechanism follows the non-overlapping small polaron tunneling model. The investigation of dielectric properties revealed that at low frequencies the dielectric constant was higher for LaHoO3 oxide than that for LaErO3. Modulus formalism examination demonstrates that the relaxation process of studied materials takes place via the hopping mechanism. [ABSTRACT FROM AUTHOR]

Using a variety of physicochemical characterization techniques, we have determined the composition and chemical formula of lanthanum and neodymium compounds with phthalic acid, synthesized for the first time. The compounds have been shown to have similar chemical formulas: La2(L)3·7H2O and Nd2(L)3·6H2O. We have examined the thermal destruction of the synthesized compounds. The proposed schematic structure of the La complex consists of zigzag 2D polymer layers, which are cross-linked by water molecules to form a 3D structure—a supramolecule. [ABSTRACT FROM AUTHOR]

La 4 Co 3 O 9 perovskite thin film was grown on a glass substrate using spray pyrolysis technique at 460 °C. X-ray diffraction (XRD) pattern indicates a high orthorhombic structure in Ruddlesden-Popper phase along (040) orientation. A nanometric scale size varying between 10 and 20 nm of the La 4 Co 3 O 9 films were proved via Transmission Electron Microscopy (TEM). The High-Resolution Transmission Electron Microscopy (HRTEM) specifically displayed the lattice fringe among the (040) and (1 10 0) planes. A direct transition band was revealed in the synthesized La 4 Co 3 O 9 films through transmittance and reflectance spectra, with a band gap of 1.42 eV. Urbach effect as well as a relatively high absorptivity were evidenced. The prepared thin films exhibit a ferromagnetic behaviour. The saturated magnetization (M S) and coercive field (H C) were equal to M S = 4.69810−4 emu/g and an H C = 45.56 Oe, respectively, at room temperature. The revealed ferromagnetic behaviour was due to the non-stoichiometry of La 4 Co 3 O 9 constituents. The present work emphasizes the specificity and suitability of La 4 Co 3 O 9 thin film perovskite for magneto-optical applications. [ABSTRACT FROM AUTHOR]

A significant structural modification and enhancement of the electrical and magnetic properties with dilute substitution of Zr (≤1mol.%) in the Bi0.8La0.2Fe1-xZrxO3 system has been reported. A mixture of rhombohedral and orthorhombic phases was detected in these conventionally sintered ceramics. Transition from a leaky state to an insulating state was observed upon Zr substitution. This is the first time that a drop in the electrical conductivity as large as 6 orders of magnitude for doping as small as 0.25mol. % in bismuth ferrite systems has been reported. An investigation on the nature of this abrupt transition revealed the dominant role of defects. A proper consideration of possible defect reactions taking place during and after sintering satisfactorily accounts for the observed modulation in the electrical properties. Both AC and DC measurements indicate that, before Zr substitution, ptype hopping conduction prevails with an activation energy as low as ~0.57 eV, whereas the Zr substitution makes oxide ion migration the central mechanism for conduction with the activation energy of ~0.96-1.08 eV. In contrast to that, the magnetic properties of the compounds experience a more subtle effect; a gradual modification of saturation magnetization and coercivity with Zr substitution is observed. Curve fitting of the magnetic hysteresis loops not only allowed extraction of three separate contributions from the magnetic response but also helped to explain the effects of Zr on the magnetic properties. Modifications of structural characteristics and magnetic anisotropy of the samples are believed to be the primary driving force behind the improvement in the magnetic properties. [ABSTRACT FROM AUTHOR]

The systematic study on structural properties of Ba-substituted La0.9Sr0.1Al0.9Mg0.1O3-δ and its correlation with conductivity was carried out. X-ray diffraction patterns indicated that the system formed a single phase composition up to 3% of Ba double substitution at the La-site. Energy dispersive X-ray spectroscopy and XPS results confirmed elemental compositions and revealed the maximum deficiency in oxygen for the 3% Ba-substituted sample. Dense grain formation is observed in SEM images, complementing higher density of these samples (>93%). Electrical conductivity was found to be in correlation with a new structural parameter of the critical triangle of (La/Sr/Ba)- Al/Mg-(La/Sr/Ba). The value of conductivity increased by an order of 2 in a substituted sample as compared to pure LaAlO3. The activation energy can be correlated with the area of the critical triangle of (La/Sr/Ba)-Al/Mg-(La/Sr/Ba). The migration path for ionic conduction of the oxygen ion was mapped out using the correlation of bulk conductivity with the A-A-B angle (β) and dc conductivity with the A-B-A angle (α). [ABSTRACT FROM AUTHOR]

The two non‐isostructural lanthanum pnictogenide selenides La3NSe3 and La3PSe3 are formed by oxidizing lanthanum metal with sodium azide (NaN3) in the presence of selenium and an excess of iodine for eight days at 850 °C and by reacting the two binary compounds lanthanum sesquiselenide (La2Se3) and lanthanum monophosphide (LaP) for four days at 900 °C in torch‐sealed glassy silica ampoules. La3NSe3 crystallizes with the well‐known Sm3NS3‐type structure in the orthorhombic space group Pnma with the lattice parameters a=1278.56(8) pm, b=424.18(3) pm, c=1358.73(9) pm, while La3PSe3 adopts the cubic Th3P4‐type structure in the space group I4‾3d with the lattice parameter a=901.42(6) pm, both for Z=4. It features one crystallographically distinct cationic La3+ site and a mixed anionic site with both P3− and Se2− anions sharing the same crystallographic position in its crystal structure. In contrast, the crystal structure of La3NSe3 is comprised of three different La3+ cations with one N3− and three distinct Se2− anions. The key structural elements are N3− centered (La3+)4 tetrahedra connected via vertices to form one‐dimensionally infinite chains ∞1{[N(La1,2)2/1t(La3)2/2v]6+} (t=terminal, v=vertex‐sharing). The comparatively large La3+ cation adopts coordination numbers of six (1×) and seven (2×) in La3NSe3, whereas in La3PSe3, the coordination number of the single cation site is eight. [ABSTRACT FROM AUTHOR]

Tunable liquid crystal (LC) alignment with twisted nematic (TN) and vertical alignment (VA) driving modes is achieved by a convenient brush‐coating method. The brush‐coating process combines film deposition and alignment treatment processes, and lanthanum aluminum zirconium zinc oxide (LaAlZrZnO) is used for the LC alignment layer. X‐ray photoelectron spectroscopy results confirm LaAlZrZnO film formation with fine optical transparency. Atomic force microscopy and line profile data indicate nano/micro surface structure with dense or directional morphologies induced by shear stresses according to film curing temperature. Low‐temperature‐cured films exhibit hydrophobic properties with low surface energy, whereas high‐temperature‐cured films show hydrophilicity with high surface energy. The geometric constraints and chemical affinities of the films induce homeotropic and homogeneous LC alignments on the surface according to the film curing temperature, respectively. The LC alignment state is verified by polarized optical microscopy and pretilt angle analysis. The brush‐coated LaAlZrZnO film demonstrates high thermal budget for advanced LC systems. The VA‐mode and TN‐mode LC cells based on the LaAlZrZnO film enable high electro‐optical performances and low power consumption. Therefore, the brush‐coating method is expected to be adoptable for next‐generation LC device applications. [ABSTRACT FROM AUTHOR]

A bifunctional electroactive filter was rationally fabricated for simultaneous oxidation and sequestration of toxic trivalent arsentic As ( Ⅲ ). A novel nanoscale La(OH)3 modified electrochemical carbon nanotube ( CNT ) network filter was prepared by a facile electrodeposition strategy. The As ( Ⅲ) decontamination kinetics and adsorption capacity were both found to increase with the flow rate ( 1. 5 - 6. 0 mL/ min) and the applied voltage ( 0 - 2. 5 V). The CNT filter hybridized with La (OH)3 ( CNT-La(OH)3 ) has demonstrated the ultra-high adsorption capacity of 750. 2 mg / g for As ( Ⅲ), which is ascribed to the combined role of sufficient adsorption sites, flow-through filtration and electric field. XPS analysis revealed that the As ( Ⅲ ) decontamination mechanism involved a two-step adsorption-oxidation process. The formation of inner-sphere La-O-As complexes, ligand exchange and electro-adsorption are all parts of the As(Ⅲ) adsorption process. The adsorbed neutrally-charged As(Ⅲ) was further oxidized to negatively-charged As ( V) when aided by an electric field, which could be effectively sequestrated by La(OH)3 . The CNT-La(OH)3 filter shows high stability under alkaline conditions and can be regenerated with dilute NaOH solution. In this study, all experiment results have demonstrated a promising and effective CNT-La ( OH)3 electrochemical filter for As (Ⅲ) pollution minimization. [ABSTRACT FROM AUTHOR]

We have presented the structural, elastic, electronic, phononic, and electron-phonon interaction properties of the La-based noncentrosymmetric superconductors, such as LaIrSi3, LaRhSi3, and LaPdSi3, by using the generalized gradient approximation of the density functional theory. The calculated elastic constants reveal the mechanical stability of all the studied compounds in their noncentrosymmetric structure, while the lack of inversion symmetry gives rise to lift the degeneracy of their electronic bands, except in the Γ-Z and X-P directions. The calculated Eliashberg spectral function shows that all phonon branches of these materials couple considerably with electrons, and thus, all of them make contribution to the average electron-phonon coupling parameter λ. Using the calculated values of λ and the logarithmically averaged phonon frequency ωln, the superconducting critical temperature Tc values for LaIrSi3, LaRhSi3, and LaPdSi3 are estimated to be 0.89, 2.56, and 2.40 K, respectively, which accord very well with their corresponding experimental values of 0.77, 2.16, and 2.60 K. [ABSTRACT FROM AUTHOR]

La2Mo2O9 (LMO) thin films have been deposited on Pt/Ti/SiO2/Si substrates by pulsed laser deposition and the resistive switching (RS) characteristics of the Au/LMO/Pt devices has been investigated. The Au/LMO/Pt devices show excellent unipolar RS characteristics with high resistance ratio between high resistance state and low resistance state (LRS), good endurance, and retention performances. The results of temperature dependence of resistance and x-ray photoelectron spectroscopy suggest that the observed RS characteristics can be explained by the formation and rupture of conducting filaments composed of oxygen vacancies. Furthermore, the plot of the reset current (IR) as a function of the third harmonic coefficient (B0) caused by Joule heating during the reset process shows scaling behavior with a power law of IR∝ B0-δ. The IR and reset power (PR) can also be scaled to the resistance in LRS (R0), i.e., IR(PR) ∝ R0-α(β). The observed scaling behaviors indicate the importance of the Joule heating for the RS characteristics of Au/LMO/Pt devices. These results demonstrate the potential application of LMO thin film in a nonvolatile memory device. [ABSTRACT FROM AUTHOR]

Investigations are being conducted on chitosan-based polymeric films that have been encapsulated with lanthanum, samarium, and graphene oxide. The primary distinguishing signals of chitosan (CS) and other components were seen in the FTIR spectra. Additionally, the interaction of the CS with the oxy-components clearly increased the crystallinity, as shown by the XRD pattern. The optical data shows that both Sm 2 O 3 and GO cause diminishing in band gap while lanthanum oxide cause a significant widening in it. Additionally, this study discusses the impact of mixed oxides insertion on the cytotoxicity of La 2 O 3 /Sm 2 O 3 /GO@CS film toward human lung cell-line. Cell viability is seen to be 123.21 % when 2.2 g/ml is utilized, and 117.95 % when 4.4 g/ml is used. Viability percentages of 29.49 and 27.31 % are obtained using 2250 and 4500 g/ml, respectively. The obtained data showed that the CS-based films behaved in a promising way when it came to healing wounds. [Display omitted] • La 2 O 3 /Sm 2 O 3 /GO@CS scaffold is fabricated via casting technique. • Sm 2 O 3 and GO cause diminishing in band gap while lanthanum oxide causes a significant widening in it. • Cytotoxicity of La 2 O 3 /Sm 2 O 3 /GO@CS film toward human lung cell-line. • Cell viability is seen to be 123.21 % when 2.2 g/ml is utilized, and 117.95 % when 4.4 g/ml is used. [ABSTRACT FROM AUTHOR]

In this work Full Potential study performed on Lanthanum compounds to analyze its photovoltaic properties. Five different combinations of Lanthanum and Indium with phosphorus are chosen in this study are La 3 P, La 2 InP, LaIn 2 P, LaP and InP. The optical, structural, thermoelectric, thermal, and electronic properties of all the above-mentioned compounds are analyzed using Density Functional Theory (DFT) applied in the WIEN2k software. Based on the analysis of electronic properties is concluded that La 3 P, LaP, La 2 InP and LaIn 2 P are conductors whereas InP is semiconductor (direct band gap) with band gap (energy) value 0.39 eV. The optical properties analysis shows these materials have desirable properties in the near UV or in the UV region. The low value of Gibbs energy indicates high thermodynamic stability. Power factor values for La 2 InP, LaP, InP and La 3 P are found to be in agreement with existing thermoelectric material, rendering them as potential thermal photovoltaic materials. [Display omitted] • Full Potential study performed on Lanthanum compounds to analyze its photovoltaic properties. • Five different combinations of Lanthanum and Indium with phosphorus are chosen for this analysis. • Density Functional Theory (DFT) as implemented in WIEN2k software were used to investigate different properties. • Power factor values of La 2 InP, LaP, InP and La 3 P confirm good thermoelectric properties. [ABSTRACT FROM AUTHOR]

Water pollution is a serious global environmental problem as many pollutants are highly carcinogenic to humans (e.g., arsenic) and cause disruption in the ecosystem (e.g., phosphorus for eutrophication). Therefore, development and application of cost-effective technologies are of great importance to meet the increasing stringent regulations and the greater challenges in the water contamination. This article provides a comprehensive review of publications in lanthanum (La)-based adsorbents that are exceptionally effective for the removal of several common inorganic contaminants from aqueous solutions. The abilities of lanthanum compounds (e.g., La2(CO3)3) as standalone adsorbents or La-incorporated adsorbents (e.g., with activated carbons) were summarized and discussed in detail. The reported studies have demonstrated that the lanthanum compounds particularly work well in the adsorption of inorganic anions (e.g., arsenic and fluoride). In addition, the incorporation of lanthanum onto some supporting materials would result in better adsorption with a lower material cost, due to better dispersion of lanthanum and well distributed active functional groups. The mechanisms of adsorption mainly include ligand exchange, surface complexation and electrostatic attraction. Various evidences given in the literatures demonstrate that, the La-based adsorbents are commercially viable and well outperform the commercial materials (e.g., ion exchange resins, activated carbons and iron oxides) for the water and wastewater treatment, in particular for the removal of anionic pollutants. [ABSTRACT FROM AUTHOR]

In this study, zinc oxide (ZnO) nanofibers were prepared using the electrospinning method, and the effects of different spinning voltages and annealing temperatures on the fiber structure were tested. La 0.8 Sr 0.2 FeO 3 (LSFO) perovskite film was prepared by a sol-gel method. Then we dip LSFO on ZnO nanofiber and grow it on the interdigital gold electrode substrate for gas sensors. The results show that the ZnO/LSFO heterostructure gas sensor has a good sensing response to H 2 S gas and exhibits good gas selectivity. The best gas response is 52.17% under 4 ppm H 2 S and work temperature 200°C, which has good recovery and reproducibility. [ABSTRACT FROM AUTHOR]

The chemical bath deposition technique was employed to synthesize unsubstituted and different percentages of La-substituted ZnO-nanoscaled thin films on a glass substrate with nominal concentrations of 0.0%, 3%, and 7%. Microwave irradiation effects on the photocatalyst of La-substituted ZnO samples for photodegradation of Congo red dye were investigated. Crystallographic parameters of unsubstituted and La-substituted ZnO were scrutinized by XRD. It was verified that as-synthesized samples belong to the wurtzite structure. Chemical stretching of the as-prepared samples was detected using an FTIR spectrum which reflects that La substitutes in ZnO lattice. A peak of 1630 cm−1 is presently owing to the ZnO stretching and deformation. The band gap of unsubstituted and La-substituted ZnO was evaluated using a UV–Vis spectrometer, and it was substantiated that the energy band gap suppresses as La content enhances which states the existence of red shift. The electric property such as resistance of unsubstituted and La-substituted ZnO nanomaterial was intended by I–V characteristics. The optical property with surface defect study was elucidated by fluorescence spectroscopy. Visible light photosensitivity was intended by I–V characteristics. [ABSTRACT FROM AUTHOR]

In the present work, LaNi0.5Ti0.5O3 and La2NiTiO6 nanoparticles were synthesized by the modified Pechini method. LaNi0.5Ti0.5O3 was calcined at 1073 K for 17 h or 100 h, while La2NiTiO6 was calcined at 1273 K for 135 h. The double perovskite calcined at 1073 K for 17 h presented orthorhombic symmetry with Pbnm space group, mean particle size was 31.9 ± 1 nm, random ordering of Ni2+ and Ti4+ cations, Néel temperature close to 15 K, and magnetic moment of 1.29 μ B . By increasing the calcination time, this material showed the same symmetry and space group, a mean particle size of 50.7 ± 2 nm, short-range ordering of Ni2+ and Ti4+ cations, Néel temperature around 12 K, and magnetic moment of 0.96 μ B . La2NiTiO6 presented a monoclinic crystal structure, with P21/n space group, mean particle size of 80.0 ± 5 nm, rock salt ordering of Ni2+ and Ti4+, Néel temperature of approximately 23 K, and magnetic moment of 2.75 μ B . [ABSTRACT FROM AUTHOR]

For extraction of metallic lanthanum from molten NaCl-CsCl-LaCl3 solutions, the electrochemical reduction of La(III) ions on inert Mo and liquid Ga electrodes were explored. Transient electrochemical techniques have been used to explore the reduction mechanism, transport parameters and thermodynamics properties. The obtained results indicate that the electrochemical reaction of La(III) + 3ē → La on inert electrode is a single-stage irreversible process, which controlled by the charge transfer rate. Simultaneously, the diffusion coefficient of [LaCl6] 3− complex ions was obtained at different temperatures. The apparent standard potentials of La3+/La couple and La-Ga alloy vs the temperature were determined. The base thermodynamic properties of lanthanum compounds were calculated. Furthermore, the potentiostatic method of electrolysis was used for the synthesis of La-Ga alloys. [ABSTRACT FROM AUTHOR]

Herein, a systematic study of postdeposition annealing for La1−xSrxMnO3 (LSMO) films regarding their structural, electronic, (magneto‐)optical, and magnetic properties is presented. The samples are prepared by magnetron sputtering at room temperature on silicon (111) substrates with native oxide and are annealed in ambient atmosphere for 12 h in a temperature range from 600 to 875 °C. The stoichiometry of the films is investigated by X‐ray photoelectron spectroscopy (XPS), and Raman spectroscopy is utilized to investigate the vibrational modes of the films. The diagonal and off‐diagonal components of the dielectric tensor are investigated by variable‐angle spectroscopic ellipsometry and magneto‐optic Kerr effect (MOKE) spectroscopy, respectively. The remanence and the coercive field of the layers are characterized by superconducting quantum interference device (SQUID) magnetometry. The magnetic properties are found to improve with increasing annealing temperature up to 850 °C, whereas the resistivity remains within a range between 0.5 and 2 Ωcm. The highest suitable annealing temperature for applications is, however, 775 °C due to the formation of a diffusion layer between LSMO and silicon oxide at higher temperatures. [ABSTRACT FROM AUTHOR]

The electrical transport properties of La1-xSrxCoO3 (LSCO) thin films were investigated in this paper. As x increased up to 0.3, the electrical transport mechanism transferred from variable range hopping to double-exchange and the film simultaneously turned from an insulator into a conductor. Different from the bulk materials, the maximum conductivity of the film appeared at x=0.3. A novel electrical transport model was proposed to explain this unconventional phenomenon. Besides, the effects of doped Sr and oxygen vacancies on the electrical transport properties were clarified by investigated the transport behaviors of the LaCoO3, La0.7S0.3CoO3, and La0.7S0.3CoO3-ω films. We found that, when Sr was doped into the LaCoO3 film, the insulating film turns into a conductor; when oxygen atoms were removed from the La0.7S0.3CoO3 film, the conducting film goes back to an insulator. Our work could shed light on the electrical transport mechanism of the LSCO films. [ABSTRACT FROM AUTHOR]

Polystyrene film nanocomposites of 0.3mm thickness with embedded LaPO4-Pr nanoparticles (40 wt. %) have been synthesized. The luminescent and kinetic properties of these polystyrene composites with embedded LaPO4-Pr nanoparticles upon pulse X-ray excitation have been studied. The luminescence intensity of this polystyrene material significantly increases as it is loaded with inorganic LaPO4-Pr nanoparticles. Nanocomposite films reveal luminescence spectra typical for polystyrene activators (p-Terphenyl and POPOP) and two components of decay time kinetics of luminescence with 12 ns and 2.8 ns time constants, depending on nanoparticle sizes. The component with 12 ns decay constant arises due to the radiative transfer of the 5d-4f-emission of the Pr3+ ions in the LaPO4 nanoparticles to the polystyrene. The decay component with the time constant 2.8 ns originates from luminescence of polystyrene matrix excited by electrons emitted from nanoparticles due to the photoeffect. This nonradiative mechanism of energy transfer from nanoparticles to polystyrene matrices is determinative for nanoparticles, as their sizes are smaller than a mean free path of an electron. [ABSTRACT FROM AUTHOR]

The La-excess alloys La1+δ(Fe0.85Si0.15)13 (d=0.06 and 0.09) exhibit large magnetocaloric effect which has been attributed to the occurrence of itinerant-electron metamagnetic transition near the Curie temperature TC. The maximum entropy change -ΔSm was shown to be from 4.5 to 11.5 J/kg K for the applied field variation ΔH from 20 to 70 kOe, respectively. The estimated relative cooling power for ΔH=70 kOe was 418 J/kg. The alloys show a typical NaZn13-type cubic structure, featuring a doping-induced magnetovolume effect with the increase in TC. Under the applied pressure up to 2 GPa, the TC as deduced from resistance measurements decreased linearly, ΔTC=113 (for δ=0.06) and 111K (for δ=0.09), together with a corresponding decrease of resistivity, Δp=6.1 µΩ m at room temperature for both samples. At a low pressure, the effect of spontaneous magnetostriction on TC caused by applying the pressure appeared to have a similar magnitude to that of the negative magnetovolume effect caused by La-excess doping. In comparison with other stoichiometric La(Fe1-xSix)13 compounds, the pressure in our case was shown to have a smaller influence on TC. [ABSTRACT FROM AUTHOR]

The La-excess alloys La1+δ(Fe0.85Si0.15)13 (d=0.06 and 0.09) exhibit large magnetocaloric effect which has been attributed to the occurrence of itinerant-electron metamagnetic transition near the Curie temperature TC. The maximum entropy change -ΔSm was shown to be from 4.5 to 11.5 J/kg K for the applied field variation ΔH from 20 to 70 kOe, respectively. The estimated relative cooling power for ΔH=70 kOe was 418 J/kg. The alloys show a typical NaZn13-type cubic structure, featuring a doping-induced magnetovolume effect with the increase in TC. Under the applied pressure up to 2 GPa, the TC as deduced from resistance measurements decreased linearly, ΔTC=113 (for δ=0.06) and 111K (for δ=0.09), together with a corresponding decrease of resistivity, Δp=6.1 µΩ m at room temperature for both samples. At a low pressure, the effect of spontaneous magnetostriction on TC caused by applying the pressure appeared to have a similar magnitude to that of the negative magnetovolume effect caused by La-excess doping. In comparison with other stoichiometric La(Fe1-xSix)13 compounds, the pressure in our case was shown to have a smaller influence on TC. [ABSTRACT FROM AUTHOR]

A series of LaAlO3 thin films with different thicknesses were deposited by pulsed laser deposition at temperatures from 720 °C to 800 °C. The results from grazing incidence x-ray diffraction and reciprocal space mapping indicate that a thin layer of LaAlO3 adjacent to the SrTiO3 substrate remains almost coherently strained to the substrate, while the top layer starts to relax quickly above a certain critical thickness, followed by a gradual relaxation at larger film thickness when they are grown at lower temperatures. The atomic force microscopy results show that the fast relaxation is accompanied by the formation of cracks on the film surface. This can be ascribed to the larger energy release rate when compared with the resistance of LaAlO3 to cracking, according to calculations from the Griffith fracture theory. For films grown at 720 °C, a drop in sheet resistance by two orders of magnitude is observed when the top layer starts to relax, indicating a relationship between the strain and the conductivity of the two-dimensional electron gas at the LaAlO3/SrTiO3 interface. The strain engineered by growth temperature provides a useful tool for the manipulation of the electronic properties of oxide heterointerfaces. [ABSTRACT FROM AUTHOR]

LaB6 nanoparticles are widely used as solar control materials for strong near-infrared absorption and high visible transparency. In order to elucidate the origin of this unique optical property, first-principles calculations have been made for the energy-band structure and dielectric functions of RIIIB6 (RIII = Sc, Y, La, Ac). On account of the precise assessment of the energy eigenvalues of vacant states in conduction band by employing the screened exchange method, as well as to the incorporation of the Drude term, dielectric functions and various physical properties of LaB6 have been reproduced in excellent agreement with experimental values. Systematic examinations of dielectric functions and electronic structures of the trivalent metal hexaborides have clarified the origin of the visible transparency and the near-infrared plasmon absorption of RIIIB6 nanoparticles. [ABSTRACT FROM AUTHOR]

Studying the adsorption of water on the metallic LaMnO3 surface can provide insight into this complicated surface-adsorbate interaction. Using density functional theory, we investigated the adsorption of a water monomer, dimer, trimer, and a monolayer on the surface. The electronic structure of ground state configurations is explored using analysis of density of states, charge density, and crystal orbital overlap populations. We found that the interaction between the surface and water molecules is stronger than hydrogen bonding between molecules, which facilitates wetting of the surface. Adsorbed water molecules form very strong hydrogen bonds, with substantially shifted OH stretch modes. For the monolayer of adsorbed water, a hint of a bilayer is observed with a height separation of only 0.2 Å. However, simulated scanning tunneling microscopy images and vibrational spectra suggest a significant difference between the two layers due to intermolecular bonding and interaction with the substrate. [ABSTRACT FROM AUTHOR]

Aluminoborosilicate glasses containing relatively high field strength modifiers (Ca, La, and Y) have been compressed at pressures up to 3 GPa and near the glass transition temperature (Tg) and quenched to room temperature at high pressure followed by decompression. Structural changes were quantified with high-resolution 27Al and 11B MAS nuclear magnetic resonance at 14.1-18.8 T. The changes with pressure in Al and B coordinations in the recovered samples are quite large with more than 50% decreases in tetrahedral aluminum (IVAl) and 200%-300% increases in tetrahedral boron (IVB). Glasses with higher field strength modifiers (La and Y) contain more high coordinated aluminum (V,VIAl) at all pressures studied. More high coordinated boron also correlates with higher field strength modifier if all three compositions are compared on an isothermal basis. Although lowering fictive temperature and increasing pressure both increase Al and B coordinations, our study shows that the actual mechanisms for structural changes are most probably different for temperature and pressure effects. Using a rough thermodynamic model to extrapolate to higher pressures, it appears that a simple non-bridging oxygen (NBO) consumption mechanism is not sufficient to convert all the aluminum to octahedral and boron to tetrahedral coordination, suggesting other mechanisms for structural changes could occur at high pressure as NBO becomes depleted. [ABSTRACT FROM AUTHOR]

Ionically conducting lanthanum fluoride (LaF3), displaying a nanoscopic lamellar structure, has been synthesized at the surface of an aqueous solution of LaCl3 and HF. The structure and the chemical composition of the conductor have been analyzed by SEM, electron probe microanalysis, X-ray powder diffraction, FTIR, and 19F magic angle spinning nuclear magnetic resonance (NMR) spectroscopy. The fluorine dynamics have been studied by NMR diffusometry and relaxometry in a temperature range from room temperature up to 875 K. The fluorine self-diffusion coefficient of the nanostructured LaF3 is about two orders of magnitude larger than that of bulk LaF3. This novel material is highly promising for many typical applications of fluorine ionic systems. [ABSTRACT FROM AUTHOR]

Wastewater treatment via photocatalytic activity is one of the most economical and environment-friendly method. However, obtaining an efficient photocatalyst remains a challenge for researchers in this most emerging field. In this study, pure and lanthnum (La)-(1%,2% and 3%) doped zinc oxide nanoparticles (ZnO-NPs) were synthesized via sol gel chemical technique to investigate their optical, chemical and structural properties. The synthesized NPs were characterized by using UV/VIS, SEM, EDS, XRD, FTIR, PL and Raman spectroscopy. Such nanoparticles (NPs) have been used as a photocatalyst for the degradation of rhodamine B (RhB) dye. Quite interestingly, the La-doped ZnO-NPs show unique results associated with the fact that by varying the concentration of dopant, the particle size is reduced (28.09 ± 0.04 nm to 15.85 ± 0.02 nm), which leads to a decrease in band gap, i.e., shifting toward visible (3.26 eV to 3.06 eV). This attributes to the fact that doping also helps to reduce electron–hole pair recombination rate during photocatalysis, which makes La-doped ZnO-NPs the most potential photocatalyst against RhB dye. We report a maximum degradation efficiency of 84.97% in 150 min observed from La0.02Zn0.98O, which reveals that 2% doping of La is the optimal value whereas further increase in concentration, i.e., at 3% (La) band gap increases whereas degradation efficiency reduces from 84.97 to 73.37%. [ABSTRACT FROM AUTHOR]

We studied the resistive memory switching in pulsed laser deposited amorphous LaHoO3 (a-LHO) thin films for non-volatile resistive random access memory applications. Nonpolar resistive switching (RS) was achieved in Pt/a-LHO/Pt memory cells with all four possible RS modes (i.e., positive unipolar, positive bipolar, negative unipolar, and negative bipolar) having high RON/ROFF ratios (in the range of ~104-105) and non-overlapping switching voltages (set voltage, VON~±63.6-4.2V and reset voltage, VOFF~±1.3-1.6V) with a small variation of about 65-8%. Temperature dependent current-voltage (I-V) characteristics indicated the metallic conduction in low resistance states (LRS). We believe that the formation (set) and rupture (reset) of mixed conducting filaments formed out of oxygen vacancies and metallic Ho atoms could be responsible for the change in the resistance states of the memory cell. Detailed analysis of I-V characteristics further corroborated the formation of conductive nanofilaments based on metal-like (Ohmic) conduction in LRS. Simmons-Schottky emission was found to be the dominant charge transport mechanism in the high resistance state. [ABSTRACT FROM AUTHOR]