Lanthanum Content Research Articles

Figures of merit of PLZT ferroelectric ceramics for practical applications

Structural, microstructural and pyroelectric properties were investigated in PZT-based ferroelectric ceramics for a composition close to the morphotropic phase boundary (Zr/Ti = 53/47), as a function of the lanthanum content. The samples were prepared via the conventional solid-state reaction sintering method. Three compositions were synthetized and studied following the PbZr0.53Ti0.47O3 + x mole% La nominal formula, where x = 0.0, 2.5 and 5.0. The structural characterization confirmed the presence of both tetragonal and rhombohedral phases for all the studied compositions, showing a decrease in the tetragonality factor (c/a) with the increase of the lanthanum concentration. The observed decrease in the stability of the ferroelectric phase (in favor of the paraelectric one) have been discussed in light of the solubility of the doping cation into the studied PZT perovskite structure. Microstructural properties revealed low pores concentration micrographs, showing homogeneous microstructures and uniform grain-sizes. The pyroelectric response of the as-prepared PLZT samples was also investigated in a wide temperature interval. The lower lanthanum content composition exhibited the best properties, characterized by a high pyroelectric coefficient and enhanced figures of merit. These characteristics make such a composition a promising material for practical applications.

Adsorption-electrochemical mediated precipitation for phosphorus recovery from sludge filter wastewater with a lanthanum-modified cellulose sponge filter

In this study, the sludge filter wastewater is confirmed to investigate the effects of adsorption-electrochemical mediated precipitation (EMP) driven phosphorus recovery on the basis of lanthanum-modified cellulose sponge filter (LCLM) material. The adsorption-EMP method relies on in situ recovery phosphate (P) from the used desorption agent (NaOH-NaCl binary solution) via the formation of Ca5(PO4)3OH all while preserving the alkalinity of the desorption agents which benefited long-term application. The lanthanum content of LCLM was 9.0 mg/g, and the adsorption capacity reached 226.1 ± 15.2 mg P/g La at an equilibrium concentration of 3.9 mg P/L. After adsorption, 55.7 % of P was recovered, and the corresponding alkalinity increased from 1.9 mmol/L to 2.2 mmol/L. Adsorption mechanism analysis revealed that the high lanthanum usage of LCLM was attributed to the synergistic effect of the lattice oxygen of LaO and LaPO4·0.5H2O crystallite formation. Additionally, the Ca5(PO4)3OH was found precipitated in the precipitation in the cathode chamber (P-CC) rather than on the surface/section of cation exchange membrane (CEM) and cathode indicating that the P recovery process was controlled by the saturation of CaP species in the EMP system and the electromigration effect. These findings present a new strategy to promote the effective utilization of rare earth elements for P adsorption and demonstrate the potential application of adsorption-EMP systems in dephosphorization for wastewater treatment.

Ni–La coatings as electrocatalysts for hydrogen evolution reaction deposited from electrolytes based on a deep eutectic solvent

Ni–La electrocatalytic coatings were electrodeposited from electrolytes based on a eutectic mixture of choline chloride and ethylene glycol (the so-called deep eutectic solvent "ethaline") containing dissolved NiCl2 and LaCl3 salts. It was shown that in this case, nickel alloys containing up to approximately 1.75 wt.% lanthanum were formed. An increase in the cathodic current density and the content of La(III) salt in the solution contributed to a higher content of lanthanum in the electrodeposits. The presence of a lanthanum(III) salt in the electrolyte led to a noticeable leveling of the surface microprofile. The electrocatalytic activity of the deposited coatings towards the hydrogen evolution reaction was evaluated by linear voltammetry in an aqueous solution of 1 M NaOH at a temperature of 298 K. It was found that the polarization of hydrogen evolution decreased, and the exchange current density increased with an increase in the lanthanum content in the coating. For example, the calculated hydrogen evolution exchange current density is 4.2610–5 A cm–2 and 1.0310–3 A cm–2 for a lanthanum-free nickel deposit and a nickel-based coating containing 1.75 wt.% La, respectively. The increased electrocatalytic activity observed when lanthanum was introduced into the nickel matrix can be attributed to both the synergistic interaction of the nickel and lanthanum components of the alloy (as previously described, the catalytic effect resulting from the hypo-hyper-d-electron interaction of transition metals) and the presence of surface active sites with lanthanum in different oxidation states (La(III)/La(II)), which can serve as electron carriers. The significant electrocatalytic effect observed when nickel is doped with lanthanum during deposition from an electrolyte based on DES allows us to consider such electrode materials as very promising for use in the electrolytic synthesis of "green" hydrogen.

Soil chemistry, metabarcoding, and metabolome analyses reveal that a sugarcane-Dictyophora indusiata intercropping system can enhance soil health by reducing soil nitrogen loss.

Greater amounts of fertilizer are applied every year to meet the growing demand for food. Sugarcane is one of the important food sources for human beings. Here, we evaluated the effects of a sugarcane-Dictyophora indusiata (DI) intercropping system on soil health by conducting an experiment with three different treatments: (1) bagasse application (BAS process), (2) bagasse + DI (DIS process), and (3) the control (CK). We then analyzed soil chemistry, the diversity of soil bacteria and fungi, and the composition of metabolites to clarify the mechanism underlying the effects of this intercropping system on soil properties. Soil chemistry analyses revealed that the content of several soil nutrients such as nitrogen (N) and phosphorus (P) was higher in the BAS process than in the CK. In the DIS process, a large amount of soil P was consumed by DI. At the same time, the urease activity was inhibited, thus slowing down the loss of soil in the DI process, while the activity of other enzymes such as β-glucosidase and laccase was increased. It was also noticed that the content of lanthanum and calcium was higher in the BAS process than in the other treatments, and DI did not significantly alter the concentrations of these soil metal ions. Bacterial diversity was higher in the BAS process than in the other treatments, and fungal diversity was lower in the DIS process than in the other treatments. The soil metabolome analysis revealed that the abundance of carbohydrate metabolites was significantly lower in the BAS process than in the CK and the DIS process. The abundance of D(+)-talose was correlated with the content of soil nutrients. Path analysis revealed that the content of soil nutrients in the DIS process was mainly affected by fungi, bacteria, the soil metabolome, and soil enzyme activity. Our findings indicate that the sugarcane-DIS intercropping system can enhance soil health.

Effect of La3+ and Mg2+ combined system on bioactivity and osteogenesis of bioinspired La-doped magnesium phosphate composites prepared utilizing the precursor method

Lanthanum (La) compounds have attracted much attention because of low toxicity and biocompatibility. In this study, a series of La-doped magnesium phosphate composites bone repair materials (LMPCs) were prepared by the precursor method, in which the molar ratio of lanthanum was 1%, 3% and 5%, respectively. The results of X-ray powder diffraction, scanning electron microscope and compressive strength test show that La-doped magnesium phosphates (LMPs) synthesized by the precursor method have uniform particle distribution, high purity and excellent degradability. In vitro research results show that LMPCs exhibited reliable biosafety and excellent bioactivity. The introduction of lanthanum enhances the antibacterial activity of Escherichia coli and Staphylococcus aureus of the composite. Furthermore, the combined system of released La3+ and Mg2+ is more conducive to promoting the proliferation of mesenchymal stromal cells (MSC) and angiogenesis of human umbilical vein endothelial cells (HUVECs) when the content of lanthanum is 3% (referred to as LMPC-2). By up-regulating the expression of alkaline phosphatase (ALP) and Runt-related transcription factor 2 (RUNX2), LMPC-2 is prominent in promoting osteogenic differentiation, and mineralized calcium deposition in vitro. Moreover, the results of micro-CT, H&E and Masson staining confirmed the beneficial effect of the combined system of La3+ and Mg2+ on the repair of rat skull defects in vivo. These achievements will provide new strategies for improving the biological activity of LMPCs and provide reference value for bone repairing in the clinic.

Effect of lanthanum doping on the structure and optical properties of nanocrystalline vanadium pentoxide films prepared by sol–gel method

The structural and optical properties of lanthanum oxide doped nanocrystalline vanadium pentoxide films with the chemical composition xLa2O3-(1-x)V2O5.nH2O (where x = 0.25, 0.50 and 1.0 mol%) prepared by sol–gel method were studied. The XRD analysis also revealed that the (002) line is noticeable in the pure film and gets sharper by the addition of Lanthanum, which indicates a layer of intercalation between the vanadium layers. The average crystallite size decreased with increasing Lanthanum content from 4.45 nm to 3.57 nm. By using double-beam UV–VIS spectrophotometers, the optical properties were studied by measuring the absorption, reflectance and transmittance of the prepared films. Some optical parameters like absorption coefficient α, dispersion energy parameters, refractive index n, optical band gap Eop for various transition mechanisms, real parts and imaginary part of the dielectric constants and effective mass were calculated. The absorption coefficient slightly increases with increasing La content, which can be attributed to the increasing of lattice distortion as a result of crystallite size increasing as indicated in the XRD. The transition mechanism was found to be indirect allowed type with optical band gap Eop increasing relative to the La content. By assuming hydrogen like model, the carrier’s contents N were deduced. The absorption spectrum behavior in visible and UV region suggests a promising solution for solar cells and optical-electronic applications.

Lanthanum-doped Bi5Fe0.5Co0.5Ti3O15 multiferroic Aurivillius phase with improved magnetization

Bi4.2La0.8Fe0.5Co0.5Ti3O15 multiferroic ceramic system was obtained by conventional solid-state reaction method. Structural characterization from X-ray diffraction has revealed a reduction of the unit-cell volume after the incorporation of lanthanum into the structure. Raman spectroscopy exhibits local structural distortions for BO6 octahedrons in correspondence with the orthorhombic symmetry, related to the lanthanum incorporation and the partial substitution of Fe3+ by Co3+. An improved magnetization (1.1 emu/g at 15 kOe) has been obtained from the magnetic hysteresis measurements at room temperature, and in spite of the presence of magnetic secondary phases, the observed improvement can be attributed to the main Aurivillius phase. It can be explained from the influence of the La3+ doping over the Fe3+-O-Co3+ magnetic coupling. The change in slope for the real dielectric permittivity around 102 °C is associated to a magnetic transition of the Aurivillius phase. The reduction of this temperature could be related with the increase of the lanthanum content. The ferroelectric and ferromagnetic phase transitions temperatures were obtained from the differential scanning calorimetry and the thermomagnetic study.

Comparison of toxicity between lanthanum oxide nanoparticles and lanthanum chloride

Due to the wide application of rare earth elements, lanthanum (La) is gradually accumulated in our living environment. Lanthanum can enter the body through a variety of routes, which has a series of effects on various systems. As a consequence, the safety of lanthanum deserves our attention. This study aims to compare the toxicity of lanthanum oxide nanoparticles (La2O3 NPs) and lanthanum chloride (LaCl3) and enrich the toxicity evaluation of lanthanum. Therefore, a 30 d intragastal experiment was conducted. C57BL/6j mice were given by La2O3 NPs solution and LaCl3 solution respectively at doses of 0, 30, 60 and 120 mg/kg BW (lanthanum content). The results show that, compared with the control group, both La2O3 NPs and LaCl3 can reduce the body weight of female mice in the high-dose group, but for male mice, the high-dose La2O3 NPs solution can increase the body weight, while LaCl3 has the opposite effect. The coefficients of liver, kidney, heart, lung, uterine and ovaries increase first and then decrease with the exposure dose, but testes and epididymides coefficient keep increasing with the exposure of LaCl3 and La2O3 NPs. La2O3 NPs and LaCl3 can reduce the concentration of triglycerides (TG) and increase the level of low density lipoprotein (LDL), but the effect of La2O3 NPs is more obvious. La2O3 NPs and LaCl3 can reduce the concentration of malondialdehyde (MDA), increase the total antioxidant capacity (T–AOC) and enhance the activity of catalase (CAT), but LaCl3 has more obvious protective effects on oxidative stress. La2O3 NPs and LaCl3 have potential risks to liver, and the toxicity of La2O3 NPs might be higher than that of LaCl3.

Valence and magnetism in EuPd3S4 and (Y,La)xEu1−xPd3S4

The double Dirac candidate EuPd${}_{3}$S${}_{4}$ appears to exhibit a roughly 50:50 mixture of Eu${}^{2+}$ and Eu${}^{3+}$. Substituting yttrium rapidly drives the remaining europium divalent, whereas lanthanum has the opposite effect. Analysis shows that average site volumes play a dominant role in the valence distribution suggesting that local strains matter more than electron count. Remarkably, lanthanum substitution also promotes valence instability leading to the appearance of intermediate valence ``Eu${}^{2.5+}$'', the fraction of which increases with both lanthanum content and temperature. Extrapolation of the onset temperature to zero lanthanum predicts ${T}_{\text{onset}}$ \ensuremath{\sim} 340 K matching recent reports of a structural transition attributed to a loss of valence order.

The Effect of La on the Microstructure and Mechanical Properties of the (Al) + Al4(Ca,La) Wrought Alloys

This article is devoted to optimization of the chemical composition of the high-tech Al–3 wt %Ca–(0.5–2.0) wt % La–1.5 wt % Mn alloys. The perspective of a decrease in the content of lanthanum from 2 to 0.5 wt % in new alloys has been validated using advanced methods for analyzing the structure and phase composition (electron microscopy, X-ray phase analysis, thermodynamic calculation) and using the analysis of mechanical (tensile) properties formed in the course of deformation treatment. The evolution of the struc-ture of the alloys was studied in the course of thermodeformation treatment. It has been shown that upon hot rolling at 400°С with no preliminary annealing of ingots it is possible to obtain high-quality deformed semiproducts (sheets) with no surface and edge defects (up to a 90% reduction). The deformation treatmentprovides the formation of a structure with inclusions of a (Al,Mn)4(Ca,La) eutectic phase uniformly distrib-uted in an aluminum matrix and found in a form of ring-shaped precipitates of submicron sizes (300 × 150 nm). In addition, the formation of a net of low-angle boundaries (subgrains) with a mean size of ~1 μm is observed; some inclusions of a eutectic phase are found along these boundaries. This combination of struc-tural characteristics mainly determines the ability of reaching favorable mechanical properties of an alloy after hot rolling with 0.5 wt % La (the ultimate strength of 240–260 MPa, yield strength of 185–205 MPa, and rel-ative elongation of 5.5–9.0%), which are comparable with the properties of the previously studied alloy with up to 2 wt % La.

Потенциодинамическое исследование свинцового баббита БЛа (PbSb15Sn10) с лантаном в среде электролита NaCl

The results of a corrosion-electrochemical study of the effect of lanthanum additives as an alloying component on the anodic behavior of lead babbit of the BLa brand (PbSb15Sn10), in a NaCl electrolyte medium with a concentration of 0.03; 0.3 and 3.0 % (by weight) are presented. The anodic behavior of babbits was investigated by the potentiostatic method at a potential sweep rate of 2 mV/s. The lanthanum content in lead babbit BLa (PbSb15Sn10) was 0.01, 0.1, 0.50 and 1.0 % (by weight). It was found that with an increase in the concentration of chloride ion in the NaCl electrolyte, there is a shift in the negative region of the values of the potentials of corrosion, pitting formation and repassivation of babbits. The free corrosion potential of lead babbit shifts from time to time to the positive region. Regardless of the composition of babbits, an increase in the rate of their corrosion was established with an increase in the concentration of NaCl in the electrolyte. The addition of lanthanum to lead babbit increases its corrosion resistance. It is shown that lead babbit corrodes by the pitting mechanism and lanthanum as an alloying component of lead babbit BLa (PbSb15Sn10) contributes to the shift of the potentials of pitting formation and repassivation to the region of positive values. This leads to an increase in the resistance of lead babbit to pitting corrosion, and also contributes to the healing of incipient pitting foci.

Mechanochemical synthesis of alumina-based catalysts enriched with vanadia and lanthana for selective catalytic reduction of nitrogen oxides.

Novel alumina-based materials enriched with vanadia and lanthana were successfully synthesized via in situ modification using a mechanochemical method, and were applied in ammonia-induced selective catalytic reduction of nitrogen oxides (SCR process). The synthesis was optimized in terms of the ball milling time (3 or 5h), vanadium content (0.5, 1 or 2 wt% in the final product), and lanthanum content (0.5 or 1 wt% in the final product). Vanadium (V) oxide was immobilized on an alumina support to provide catalytic activity, while lanthana was introduced to increase the affinity of nitrogen oxides and create more active adsorption sites. Mechanochemical synthesis successfully produced mesoporous materials with a large specific surface area of 279-337m2/g and a wide electrokinetic potential range from 60 to (-40)mV. Catalytic tests showed that the incorporation of vanadia resulted in a very large improvement in catalytic performance compared with pristine alumina, increasing its efficiency from 14 to 63% at 400°C. The best SCR performance, a 75% nitrogen oxide conversion rate at a temperature of 450°C, was obtained for alumina enriched with 2 and 0.5wt% of vanadium and lanthanum, respectively, which may be consideredas a promising result.

Electron diffraction study and ionic conductivity of fluorite Ba1-xLaxF2+x and tysonite La1-yBayF3-y phases in the BaF2-LaF3 system

Crystals of fluorite phases with the CaF2 structure: Ba1−xLaxF2+x (x = 0, 0.05, 0.105, 0.25, 0.35, 0.40) and those of tysonite ones with the LaF3 structure: La1−yBayF3−y (y = 0, 0.05, 0.09) have been studied by electron diffraction and elemental analysis in a transmission electron microscope. Diffraction patterns of Ba1−xLaxF2+x crystals with x = 0.105, 0.25 exhibit diffuse scattering, which indicates the presence of clusters of structural defects. Blurred supercell reflections are seen in diffraction patterns of Ba1−xLaxF2+x crystals with a high lanthanum content (x = 0.35, 0.40) in addition to diffuse scattering. They indicate the existence of nanoscale ordered crystallites as well as clusters. It was found that LaF3 and the tysonite phase La1−yBayF3−y with a low barium content (y = 0.05) is of a low-temperature l-form (space group P3¯c1, Z = 6). A small fraction of tysonite crystallites in La1-yBayF3-y crystals with y = 0.09 is of a high-temperature h-form (space group P63/mmc, Z = 2). An intermediate crystal structure between l- and h-forms was also found.The maximum ionic conductivity σdc of tysonite crystals La1−yBayF3−y at 293 K is 800 times higher than that of fluorite ones Ba1−xLaxF2+x. A correlation was found between logarithm of conductivity and composition: lg σdc(x) = ax + b for fluorite Ba1−xLaxF2+x and tysonite La1−yBayF3−y crystals. The reason for the additive law of change in ionic conductivity in both types of nonstoichiometric phases in the BaF2-LaF3 system is apparently the similarity of defect structures of fluorite and tysonite phases.

The influence of lanthanum concentration on microstructural and electrical properties of Mg-Cd-Bi ferrite nanoparticles

Lanthanum (La3+) substituted Mg-Cd-Bi ferrite nanoparticles were synthesized by sol-gel auto combustion route consuming high quality nitrates. The impact of lanthanum concentration on microstructural and electrical properties in the ferrite series Mg0.5Cd0.5Fe1.95Bi0.5-xLaxO4 (x = 0.0, 0.01, 0.02, 0.03, 0.04, 0.05) was investigated. The samples were characterized by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), scanning electron microscope (SEM), and Current-voltage (I-V) analyzerfor compositional, structural, morphological and electrical analysis. Upon varying the lanthanum content, it is observed that all the samples retained perovskite BiFeO3 phase with distorted rhombohederal structure. Furthermore, it is revealed that the sintering process can significantly control the structural defects and crystal imperfections which affect the electric and magnetic nature of ferrites. The conduction process in La3+-dopedferrite series is originated by the hopping of electrons between ions of same elementswhich reduced the electrical resistivity and depicts the semiconductor nature of synthesized samples.Thus, it is believed that the optimal doping of lanthanum content in La3+-substituted Mg-Cd-Bi ferrites followed by post-annealing can remarkably tune the electrical properties of synthesized ferrite nano particles.

Heavily cerium-doped (Gd,La)AlO3 ceramic scintillators: Material optimization study

Cerium-doped aluminates with a perovskite structure are studied for their prospective material properties aiming at their application in scintillation detectors. These materials exhibit high density, and thermal and chemical stability and thanks to the allowed 5d-4f transition of Ce3+ also high scintillation emission intensity and fast decay can be obtained. Commercially successful perovskite scintillator is the cerium-doped yttrium aluminium perovskite (YAlO3:Ce) produced in single crystal form by the Czochralski method. To overcome its disadvantage of low density and effective atomic number the single crystal of gadolinium aluminium perovskite doped with cerium (GdAlO3:Ce) was studied, but has shown significantly lower light. This work pursues a new approach to improve the scintillation properties of this material. Ceramic pellets of gadolinium aluminium perovskite doped with cerium and admixed with lanthanum ((Gd,La)AlO3:Ce) were prepared using co-precipitation method. The effect of cerium and lanthanum content was studied using the radioluminescence and luminescence spectroscopy. An improvement of scintillation properties (emission intensity and decay kinetics), in comparison to GdAlO3:Ce reported so far, was achieved.

Physical characterization of BiFeO3‐based thin films with enhanced properties for photovoltaic applications

AbstractThe present paper reports the multifunctional properties of lead‐free BiFeO3–La (BFO–La) thin films. The structural, microstructural, and optical properties have been investigated as a function of the lanthanum doping concentration. The structural properties at room temperature showed the formation of the perovskite structure, thus suggesting the high quality of the obtained thin film compositions. Raman spectroscopy analysis revealed a slight variation in both the peak position and absolute intensity for the Raman active modes, as lanthanum content increases in BiFeO3–La. Crystallized thin films with well‐defined grains as well as crack‐free surfaces have been obtained, for all the studied compositions, as inferred from atomic force microscopy images. The optical properties have been measured, and the values for the direct bandgap was significantly lower than those reported for other BFO‐based systems, being the lowest ∼1.87 eV for the Bi0.90La0.10FeO3 composition. Results revealed a noteworthy effect of the defect concentrations induced by the lanthanum doping on the long‐range crystallinity and directly affecting the polarizability of the A–O bond as well as the Fe–O and Fe–O–Fe bond lengths in the perovskite structure. The enhanced optical absorption properties registered for the Bi1–xLaxFeO3 (x = 0–20) compositions make these perovskite multiferroic thin films as a potential candidate material for the high‐performance photovoltaic device applications.

Electrical transport properties of La doped BiFeO3-NaNbO3 composite

ABSTRACT The composites, (1−x)(BiFe1-yLayO3)– xNaNbO3 with x = 0.25, 0.45 and y = 0.10, 0.20, are prepared by mixed oxide method. XRD analysis shows rhombohedral (hexagonal) structure at room temperature. The properties such as dielectric loss (tanδ) and dielectric constant (ϵr ) of all the samples are studied. A significant improvement in dielectric constants has been observed with the rise of Lanthanum (La) content. A dielectric anomaly above 350°C is observed for all the studied materials. Further, it is observed that ac conductivity (σ ac) spectrum obeys universal Jonscher’s power law. The variation of σ ac with inverse of temperature for all the samples is found to obey the Arrhenius equation. The formation of loop in polarisation verses electric field curve establishes the ferroelectric (FE) nature of all the studied samples. Current (I)-Electric Field (E) loops is studied to show the behaviour of domain switching.

Effect of lanthanum content on physicochemical properties and thermal evolution of spent and beneficiated spent FCC catalysts

Two FCC spent catalysts with different amounts of La2O3 and similar Al2O3/SiO2 ratios and the corresponding residues of an optimized process of La-extraction are studied. The potential of the powders as feedstock for mullite refractories is established. The four powders have been fully characterized – chemical composition, crystalline phases, particle size, specific surface area, porosity, and morphology. Their thermal evolution up to 1500°C has been studied using dynamic techniques – hot stage microscopy, DTA-TG – and isothermal thermal treatments. The effect of powder characteristics on high temperature phase development, in particular, on mullite formation is discussed.Besides La, the La-extraction process also implies partial extraction of the matrix in which zeolites are dispersed, resulting in reduced impurities contents and Al2O3/SiO2 ratios.The powders present differences in the textural properties– porosity and specific surface area – that do not affect the high temperature behavior, which is determined by the impurities and the Al2O3/SiO2 ratio. The four powders can be proposed as precursors for mullite materials. The compositions of the spent catalysts can be envisaged for application up to 1200°C. The compositions of the residues of the La-extraction process can be proposed for higher temperatures once their composition is corrected by adding alumina to avoid extensive cristobalite formation together with mullite.

Effect of Lanthanum Content on the Formation of Acicular Ferrite

Effect of Lanthanum Content on the Formation of Acicular Ferrite

Thermoelectric properties of Sr1-xLaxNb2O6-δ (0 < x ≤ 0.4) ceramics sintered under strongly-reducing conditions

A series of oxide ceramics with the general formula of Sr1-xLaxNb2O6-δ (x = 0.1, 0.2, 0.3, 0.4) was synthesized and the characterization was study in detailed. The XPS results reveal that the heterovalent substitution of La3+ for Sr2+ leads to the Nb4+ dominated chemical state in this series of oxides, and a mass of oxygen vacancy defects exist in the oxides after annealed in strong reduction atmospheres. Due to increased phonon scattering by lattice distortion and heavier La atoms, all of the samples achieve lower thermal conductivity. The electrical resistivity and the magnitudes of Seebeck coefficient monotonically decrease with the increase of the content of lanthanum. Overall, the sample of Sr0.6La0.4Nb2O6 reaches the maximum ZT of ∼0.13 at 1073 K.