Increasing La Content Research Articles

La3+ substitution effect on structural and magnetic properties of frustrated Ho2Ti2O7 pyrochlore

A renowned quantum material Ho2Ti2O7 in which structural and magnetic properties are coupled, is identified by its unusual spin freeze state. In the current report, magnetic and structural behaviour of Ho2−xLaxTi2O7 (x = 0.0, 0.1, and 0.2) pyrochlore prepared through solid state standard method, were investigated by partial replacement of Ho3+ with nonmagnetic La3+. The XRD along with Raman spectroscopy studies confirmed single phasic cubic pyrochlore structure with red and blue shift of the phonon mode and increase in the structural ordering due to increase in the ionic radii ratio by incorporation of La in Ho2−xLaxTi2O7. Cell parameter is also increased linearly with increasing La content and follow Vegard’s rule. The crystalline size (71 ± 5 nm, 87 ± 6 nm and 107 ± 5 nm for x = 0.0, 0.1 and 0.2, respectively) calculated from W-H plot is increased with nonmagnetic La doping which is consistent with electron microscopy studies. No spin glassy pattern was traced in magnetic studies even letting down the temperature up to 2 K. It was found that Curie Weiss temperature (θCW) and effective magnetic moment (μeff) shrinking with rising chemical pressure that leads to weakening of ferromagnetic character of the compounds. Observed shift in the energy barrier is explained on the basis of change in dipolar and exchange interaction which is responsible for the magnetic behaviour of Ho2−xLaxTi2O7 pyrochlore. Furthermore, reduction in the value of θCW also depends upon the nature and location of the dopant. Large reduction in the θCW for Ho2Ti2O7 doped with La3+ suggested that doping at the A site can be used for the tuning the θCW.

Origin of Ferroelectricity in BiFeO3-Based Solid Solutions.

We investigate the origin of ferroelectricity in the BiFeO3-LaFeO3 system in rhombohedral R3c and tetragonal P4mm symmetries by ab initio density functional theory calculations and compare their electronic features with paraelectric orthorhombic Pnma symmetry. We show that a coherent accommodation of stereo-active lone pair electrons of Bi is the detrimental factor of ferroelectricity. A Bloch function arising from an indirect Bi_6p-Fe_3d hybridization mediated through O_2p is the primary origin of spontaneous polarization (Ps) in the rhombohedral system. In the orthorhombic system, a similar Bloch function was found, whereas a staggered accommodation of stereo-active lone pair electrons of Bi exclusively results in paraelectricity. A giant Ps reported in the tetragonal system originates from an orbital hybridization of Bi_6p and O_2p, where Fe-3d plays a minor role. The Ps in the rhombohedral system decreases with increasing La content, while that in the tetragonal system displays a discontinuous drop at a certain La content. We discuss the electronic factors affecting the Ps evolutions with La content.

Improving dielectric properties, electrical conductivity, and thermal properties of biodegradable polymer composites prepared with lanthanum

AbstractThe precipitation method was adapted to synthesize the poly(ε‐caprolactone‐copolymer‐ ethylene oxide) (ε‐CL‐co‐EO) composite with the salt of lanthanum (La), a rare earth element. This salt was incorporated into the polymer of different weight percentages to study how it affects the thermal and dielectric properties of the polymer. The resulting products were characterized by Fourier Transform Infrared Spectroscopy, X‐ray diffractometry (XRD), Scanning electron microscopy (SEM) and thermogravimetric analysis. XRD and SEM data show that the polymer mixes homogeneously with the metal salt. Thermal degradation data show that the thermal stability of composites synthesized with La is lower than that of pure polymer. The dielectric properties and A.C conductivity measurements of the composites were investigated by using impedance analyzer in the frequency range (100 Hz to 20 kHz) at room temperature. The electrical property results of (ε‐CL‐co‐EO)/La composites displayed that dielectric constant (έ), dielectric loss (ε"), tan delta (tan δ) and A.C electrical conductivity (σac) increase with increasing La content. The largest conductivity of (ε‐CL‐co‐EO)/La composite filled with 20 wt% La was 8.80 × 10−8 S/cm, which was 162% times pure (ε‐CL‐co‐EO). In addition, impedance (IZI) of composites was evaluated from the dielectric data. This procedure is eco‐friendly and easy to handle, which provides a promising route to polymer composites in the application of the conductivity field.

Ferroelectric (Hf,Zr,La)O2 films

The impact of La, Zr and Hf content on the crystal phases and ferroelectric and dielectric properties of (Hf,Zr,La)O2 has been determined by investigating epitaxial films. The polarization of La-doped Hf1-xZrxO2 films strongly depends on La and Zr content, with remanent polarization ranging from 0 to about 30 µC/cm2. The optimal La doping in Hf1-xZrxO2 increases from 0% to 2–5% for decreasing the Zr content from 100% (ZrO2) to 0% (HfO2). Structural characterization and dielectric permittivity measurements point to the correlation between crystal phases and polarization. In ZrO2 films, an orthorhombic/tetragonal phase mixture likely evolves into a monoclinic/cubic/tetragonal phase mixture as La doping increases. In films with Hf content, when La content increases, the phases present in Hf0.5Zr0.5O2 progressively evolve from orthorhombic and monoclinic to cubic, and in HfO2 from monoclinic, to orthorhombic, and finally to cubic. This map of phases and polarization in the Hf-Zr-La oxide, established with epitaxial films, can be a model system for polycrystalline samples.

Nanoscale microstructure and hydrogen storage performance of as cast La-containing V-based multicomponent alloys

Vanadium-based alloys (VBAs) occupy a prominent position in the field of hydrogen storage materials due to their many advantages, including the ability to absorb/desorb hydrogen with high capacity under moderate conditions. However, the kinetic and thermodynamic properties of these alloys must be improved to expand the range of their practical applications. In this work, we systematically studied the influence of La doping on the microstructure and hydrogen storage performance of multicomponent VBAs. It was found that the as-cast multicomponent V48Fe12Ti30Cr10 alloy prepared by arc melting contained micrometer/nanometer-sized crystals, which differed from the microstructure of traditional coarse-grained VBAs fabricated in the past decades. After the alloy was doped with La metal, its grains were refined into nanocrystallites with remarkable hydrogen absorption properties. This indicates that nanostructured VBAs can be realized by casting techniques, which is a traditional, low-cost, and engineering approach. The hydrogen storage capacity of the alloys first increased and then decreased with increasing La content. Furthermore, La doping considerably increased the alloy cycling stability. These findings can be used to develop novel hydrogen absorption materials for fuel cells with superior kinetic and thermodynamic properties.

Oxygen migration energy in La and Y Co-doped CeO2: Effect of lattice constant and grain boundary segregation

The transfer energy of oxygen vacancy of La and Y co-doped CeO 2 is investigated in which the total amount of La and Y is fixed at 20 at%. Although both the La 3+ (1.16 Å) and Y 3+ (1.032 Å) ions are larger than the Ce 4+ ions (0.97 Å), individual single doping of La and Y results in an increase and a decrease in the CeO 2 lattice constant, respectively, due to the effect of the critical ionic radius ( r c ). As the La/Y ratio varies, the lattice constant increases as the La content increases, which leads to a decrease in the migration energy of the oxygen vacancy in the grain interior. When La and Y are co-doped at a ratio of 2:18, its lattice constant is almost the same as that of pure CeO 2 in which the dissociation energy of the oxygen vacancy achieves the lowest value due to the minimum lattice-strain energy. The migration energy at the grain boundary also decreases with increasing La content. This result is explained by the degree of grain boundary segregation of the dopant.

Effect of La doping on dielectric constant and tetragonality of ZrO2 thin films deposited by atomic layer deposition

The electrical properties of La-doped ZrO2 thin films were studied for an application to cell capacitors in dynamic random-access memory. La-doped ZrO2 thin films were deposited by changing the ratio of ZrO2:La2O3 cycles using atomic layer deposition. Grazing-incidence X-ray diffraction analysis showed that the La-doped ZrO2 thin films had a tetragonal structure. The tetragonality (c/a) of La-doped ZrO2 thin films increased from 1.41 in undoped ZrO2 to 1.43 in La-doped ZrO2 with a 7.5% La content. X-ray photoelectron spectroscopy showed that the concentration of oxygen vacancies in ZrO2 thin films increased with increasing La concentration. The dielectric constant of La-doped ZrO2 was increased by 15% from 37 in undoped ZrO2 to 43 at a La doping concentration of 7.5%, and the leakage current was also improved. Therefore, La-doped ZrO2 thin films are expected to be an excellent candidate material for dynamic random-access memory cell capacitors owing to their high dielectric constant and low leakage current.

Microstructure and properties of La-doped Er2O3 anti-reflection films on CVD diamond

The composition and microstructure consisting of anti-reflection films was obtained by the power of magnetron sputtering. X-ray photoelectron spectroscopy (XPS) and High-resolution transmission electron microscopy (HRTEM) provided evidence to support that the doping La element exists as oxide in the grain boundaries of the matrix Er2O3 films. The undoped and La-doped Er2O3 films show a columnar crystal structure of the main cubic (222) plane. Twinning and a large number of dislocations show up in the undoped Er2O3 films due to the competitive growth of the columnar crystal. In addition, the La-doped Er2O3 films show a lower roughness (RMS) value in comparison with undoped Er2O3 films. The grain size of columnar crystals decreases significantly with increasing La concentration in the La-doped Er2O3 films. The fine grains resulted in the La-doped Er2O3 films developing high mechanical and impact resistance properties, with an increase in hardness from 12.6 ± 2.1 GPa to 26.1 ± 3.4 GPa and the eroding area rate decreasing from 38.9 % to 1.9 %. Moreover, the La-doped Er2O3 anti-reflection films on the chemical vapor deposition (CVD) diamond substrate maintained 74 % transmittance in the long-wavelength infrared range of 8–12 μm after sand eroding.

Green one-step reduction approach to prepare rGO@AgNPs coupled with molecularly imprinted polymer for selective electrochemical detection of lactic acid as a cancer biomarker

Herein, for the first time, we report a novel one-step green reduction approach of reduced graphene oxide decorated with silver nanoparticles (rGO-AgNPs) that is both cost-effective and ecologically friendly using Allium sativum extract. The rGO-AgNPs were then coupled with a molecularly imprinted polymer to create a highly sensitive selective electrochemical sensor to detect lactic acid, a key agent in cancer cell screening. The scanning electron microscope, X-ray diffraction, and Fourier-transform infrared spectroscopy were used to study the morphology and surface characteristics of the synthesized nanomaterials. In contrast, cyclic voltammetry was used to characterize the modified electrodes in the presence of [Fe(CN)6]3-/4-. The electrochemical detection of LA was indirectly performed using AuE/rGO-AgNPs/MIP and based on the signal generated from [Fe(CN)6]3-/4- redox peaks which were steadily decreased with the increase of LA concentration due to the interruption of electron transfer paths suggesting high sensitivity towards the target molecule. The current variation ΔI(I BLANK - I LA) was directly proportional to LA concentration between 10 and 250 μM with a very low detection limit of 0.726 μM (S/N = 3). The developed LA sensor revealed an excellent selectivity with strong stability. Furthermore, the LA sensor robustness was tested against different pH mediums, and good results were obtained; the practical use of the developed sensor was validated in human serum samples revealing the strong potential use in cancer screening and monitoring.

Enhanced energy-storage properties of La2O3 doped (Na0.5Bi0.5)0.705Ba0.045Sr0.25TiO3 lead-free ferroelectric ceramics

The powder samples of (Na0.5Bi0.5)0.705Ba0.045Sr0.25TiO3-xLa2O3 (NBBSLT) have been prepared successfully by a wet solid-phase method. The effects of La doping on the morphology, ferroelectric and dielectric properties of NBBSLT ceramics were studied. XRD results show that the composite has perovskite structure. The dense phase morphology of NBBSLT was observed by SEM. Dielectric measurements show that depolarization temperature and Curie temperature move toward low temperature. With the increase of La content, the ferroelectric hysteresis loops at room temperature become thinner at first and then wider. The NBBSLT ceramics have excellent energy storage properties when the La content is 0.04.

Structure and electrical properties of BaCe1−xLaxO3−δ mixed conductors

In this study, BaCe1−xLaxO3−δ (x = 0.05, 0.10, 0.20, and 0.30) oxides synthesized using citrate–nitrate combustion method were calcined at 1100 °C for 5 h and subsequently sintered at 1550 °C for 5 h. Crystal structure, conductivity, and chemical properties were investigated via X-ray diffraction (XRD), alternating current (AC) impedance spectroscopy, and X-ray photoelectron spectroscopy (XPS). XRD analysis shows that all samples have orthorhombic perovskite-type structure, and lattice volume increases with increasing La content. XPS results show that Ba and La valence states are bivalent, and trivalent, respectively. Mixed Ce4+ and Ce3+ valence states can be identified in the samples. Furthermore, there are two types of O binding states in perovskite structure: (i) O–H groups/oxygen vacancies and (ii) lattice oxygen. AC impedance spectra reveal that all samples are proton–oxide ion–electron hole conductors at 400–800 °C in wet O2 atmosphere and proton–electron conductors at 400–800 °C in wet Ar atmosphere. Among these samples, BaCe0.90La0.10O3−δ and BaCe0.95La0.05O3−δ display the highest conductivities at temperatures below and above 500 °C, respectively. Furthermore, BaCe0.95La0.05O3−δ exhibits the highest total conductivity of 1.06 × 10−2 S cm−1 at 800 °C under PO2 ≈ 1 atm and PH2O = 0.006 atm.

Epitaxial growth and phase evolution of ferroelectric La-doped HfO2 films

Hafnium-oxide-based materials are considered a promising candidate for next-generation nonvolatile memory devices owing to their good CMOS compatibility and robust ferroelectricity at the nanoscale. In this work, we synthesize highly (111)-oriented La-doped HfO2 (HLO) ferroelectric thin films via pulsed laser deposition. Furthermore, the effect of La dopant concentration, thickness, and growth temperature on the ferroelectricity of HLO films is investigated in detail. A maximum remnant polarization of ∼9 μC/cm2 is achieved for only the 5-nm-thick 3 mol. % HLO films without a wake-up process. The 180° inversion of the domain, the butterfly-shaped capacitance–voltage curve, and typical ferroelectric displacement current curve further demonstrate the robust ferroelectricity at the nanoscale. Moreover, the phase evolves from the monoclinic to the orthorhombic and subsequently to the cubic phase with increasing La concentration, which is due to the combined action of oxygen vacancy, epitaxial strain, and chemical pressure. Additionally, in the interface configuration of HLO/La0.7Sr0.3MnO3 (LSMO), the MnO20.7− layer is substituted by the HLO layer on the MnO2-terminated surface of LSMO, which can be attributed to the fact that the HLO layer with higher electronegativity replaces the MnO20.7− layer with the same electronegativity in the HLO film. Therefore, this study provides a reliable pathway for directly obtaining a lightly doped HLO ferroelectric thin film, which can help to broaden the understanding of the ferroelectric physical mechanisms with element doping.

Ce site dilution effects in the antiferromagnetic heavy fermion CeIn3

La-doped intermetallic single crystals of ${{\mathrm{Ce}}_{1}}_{\ensuremath{-}x}{\mathrm{La}}_{x}{\mathrm{In}}_{3}$ were synthesized via an In self-flux method throughout the entire range $(x=0--1)$. The prototypical heavy-fermion compound ${\mathrm{CeIn}}_{3}$ shows an antiferromagnetic phase transition at 10.1 K and becomes superconducting near a critical pressure where ${T}_{N}$ is completely suppressed. As the La concentration increases, Ce moments are diluted, and the lattice constant increases linearly, satisfying Vegard's law. The electrical resistivity of the high-quality single crystals of ${{\mathrm{Ce}}_{1}}_{\ensuremath{-}x}{\mathrm{La}}_{x}{\mathrm{In}}_{3}$ shows a gradual suppression of ${T}_{N}$ to 0 K at approximately ${x}_{c}=0.65$. The sign of the slope of the low-temperature resistivity vs temperature changes from positive to negative in the vicinity of the critical concentration ${x}_{c}$, indicating a change in the Kondo ground states from the Kondo lattice to the Kondo impurity state. In the Kondo lattice state $(x<{x}_{c})$, the coherence temperature $(=50\phantom{\rule{0.16em}{0ex}}\mathrm{K})$ assigned as the peak in the resistivity is almost independent of the La concentration. In the Kondo impurity state $(x>{x}_{c})$, on the other hand, a kinklike feature in the resistivity appears at $\ensuremath{\sim}50\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ and persists up to $x=0.97$, indicating a change of the Kondo scattering owing to the crystalline electric field effects. These results suggest that the critical concentration is closely connected to the emergence of the Kondo coherence state.

Structural evolution of La-modified AgNbO3 lead-free ceramics: Perspective from octahedral tilting and tolerance factor

Systematic studies on the structural and microstructural properties as a function of the lanthanum concentration have been performed in AgNbO3-based lead-free ceramics, which were synthesized via the conventional solid-state reaction process. The structural analysis has been carried out at room temperature by the X-ray diffraction technique as well as Raman spectroscopy. A single-phase orthorhombic polycrystalline perovskite structure, without undesired phases, has been confirmed for all studied compositions. Structural distortions, which have been associated with the doping concentration, have been investigated through Rietveld refinement and Raman results. The La3+ ion concentration has also shown an important influence on the Raman spectra, showing a wavenumber shift and a dramatic change in absolute intensity of several bands with the increase of the lanthanum dopant. With a further inclusion of the doping element, a change in the local structural properties is revealed, detecting additional bands in the 90–93 cm−1 and 570−758 cm−1 ranges of Raman spectra. The microstructure is strongly influenced by the additive content, revealing a decrease in grain-size as the La-content increases.

Enhancement in room temperature ammonia sensing performance of the La substituted SnO2 (La:SnO2) thin films developed using spray pyrolysis technique

In this report, pristine SnO2 and La doped SnO2 (La:SnO2) thin films were synthesized using the spray pyrolysis technique and their gas sensing performance operated at room temperature in the presence of ammonia (50 to 250 ppm) were analyzed. The La:SnO2 thin films were developed in four different La concentration like 0, 1, 3 & 5% in SnO2. All the prepared thin film samples were characterized using different analytical techniques for analyzing their properties. The XRD result shows the prepared La:SnO2(0, 1, 3 & 5%) thin films exhibits a tetragonal rutile structure of SnO2 without any secondary impurities according the JCPDS data (41–1445). Also, the crystallite size increases with the La doping concentration at 1% and decreases with further increase in La concentration (3 & 5%) could due to the deterioration of the grain growth of the Sn-O lattice. The scanning electron microscope (SEM) results shows the La:SnO2 thin films possess a tetragonal structures with different nano size particles and the energy dispersive x-ray analysis (EDX) confirms the presence of Sn, O & La elements. The optical results suggest that the transparency increases with the introduction of the La dopants slightly shifted towards the blue region. The bandgap of the samples increases with the increase in La concentration which is according to the Moss- Burstein effect. The photoluminescence (PL) studies confirms the 1% La:SnO2 thin films has higher defect sites due to the presence of oxygen vacancies. Finally, the gas sensing properties of the samples shows that the 1% La:SnO2 exhibits high response of 128% for 250 ppm of ammonia gas at room temperature. Also, 1% La:SnO2 possess stable current value for the fixed concentration of ammonia (250 ppm) during five cycles. This results suggests that the fabricated 1% La:SnO2 thin film sensor can be better suited for the commercial gas sensing application.

Impact of La on Structural, Morphological and Magnetic Properties of NiCoFe2O4 Nano Ferrites

Abstract: Ni0.2Co0.8Fe2-xLaxO4 (x = 0.02, 0.06, 0.10) nano ferrites have been synthesized by Sol-gel auto combustion method using urea as a fuel. The sample calcinations have been performed at 800 oC for 4 hours. The synthesized samples were subjected to study X-ray diffraction spectroscopy (XRD) for structural investigations. All the samples were found to constitute Face Centered Cubic (FCC) spinel structure belonging to the Fd3m space group. The XRD results show the single cubical phase formation in the heated samples. Energy-dispersive X-ray spectra confirmed the presence of Ni, Co, La Fe and O elements with no existence of any impurity. The average crystallite size was decreased by varying the concentration of La from 10 to 8 nm. The Field Emission Gun Scanning Electron microscopy (FEG-SEM) and Field Emission Gun transmission electron microscopy (FEG-TEM) have given the morphological study of the samples. It is also found that the value of the lattice constant decreases with increases in La concentration. The magnetic properties of the samples were investigated by using a vibrating sample magnetometer (VSM). The results obtained from VSM show that the value of both magnetization (Ms) and coercivity (Hc) decreases with an increase in diamagnetic La concentration. Keywords: Spinel ferrites, Sol-gel, SEM, TEM, VSM.

From Doping to Dilution: Local Chemistry and Collective Interactions of La in HfO2

Lanthanum (La) doping is considered as a promising route to overcome reliability issues of switchable ferroelectric HfO2‐based devices. This study links the local chemistry at the La lattice sites with local and collective electronic properties of the La:HfO2matrix using hard X‐ray photoelectron spectroscopy. The satellite structure of the La 3dcore level, the plasmonic excitation energies, and core‐level rigid binding energy shifts are investigated for La:HfO2samples with a wide range of La doping, ranging from 3.5% to 33%, i.e., from the doping to dilution level. The emerging chemical phases and electronic properties are discussed as a function of La content. From the evolution of the plasmon excitation energies and rigid binding energy shifts, it is concluded that electronic charge compensation by oxygen vacancies occurs for increasing La content.

Microstructural evolution in as-cast hypereutectic Al-Si alloys with different La additions

Abstract The microstructure of as-cast hypereutectic Al-(17 or 25) Si-xLa (x - 0, 0.4, 1, 3, 6 wt.%) alloys and the effect of La on the Si phase have been investigated. The microstructure was examined using optical and electron microscopy. The modification effects of La addition on the morphology and size of both the primary and the eutectic Si were observed. However, such effects are uneven and there seems no systematic change for the effectiveness of La modification with increasing La contents. The modification of La may be explained by the suppression of the growth of Si crystals through reduction of the eutectic reaction temperature or through enveloping of primary Si crystals, or additional twinning. Large particles of La-rich compounds are always observed associated with large primary Si crystals and unmodified eutectic Si crystals, while small La-rich particles are associated with small primary Si crystals and modified eutectic Si crystals. The overall concentration of La-rich compounds, formed in the Al–Si alloys containing more than 1 wt.% La, could be represented as a ternary AlSi2La2 phase, which actually contains the LaSi2 phase and an unknown ternary Al x Si y La phase.

Enhancement in optoelectronic properties of lanthanum co-doped CdO: Zn thin films for TCO applications

This work reports on structural, electrical, optical, and photosensing properties of La and Zn co-doped CdO thin films . The co-doped CdO thin films were prepared on glass substrates using the nebulizer spray method at 350 °C. From the structural analysis, a decrease in the crystallite size from 20 to 16 nm is observed against the incorporation of La in CdO:Zn. Inclusion of La in CdO:Zn has also changed the surface morphology with a reduction in the roughness of the thin film samples. EDX analysis confirmed the incorporation of La with CdO: Zn in the prepared films. The bandgap value of the prepared samples increased with the increase in La concentration. A 1.5 wt% of La co-doped with CdO:Zn thin film sample produces low resistivity of 6.81 × 10 -4 Ω cm and a better figure of merit of 8.4 × 10 −4 Ω -1 . Finally, the fabricated photodetector with 1.5 wt% of La co-doped with CdO:Zn thin film shows a higher photocurrent and an ideality factor value of 3.4 . The photosensing properties of the fabricated (p-Si/CdO–Zn–La (1.5%)) photodetector shows a higher responsivity (R) value of 1.18 AW -1 , specific detectivity (D*) value of 4.90 × 10 9 Jones, and external quantum efficiency (EQE) value of 274% with 3.0 mW/cm 2 light intensity . The switching characteristics of the photodetector show a faster rise time (2.9s) and fall time (3.6s) suggesting the fabricated device suitable for photosensing applications. • Doping of La in CdO:Zn has changed the surface morphology with a reduction in the roughness of the samples. • A 1.5 wt% of La co-doped CdO:Zn sample produces low resistivity of 0.68 Ωcm and a better figure of merit of 8.4 × 10 −4 Ω -1 . • Fabricated p-Si/CdO–Zn–La (1.5%)) photodetector shows a higher responsivity (R) value of 1.18 AW -1 , specific detectivity (D*) value of 4.90 × 10 9 Jones, and external quantum efficiency (EQE) value of 274%. • The switching characteristics of the photodetector show a faster rise time (2.9s) and fall time (3.6s).

Effects of La Addition on the Microstructure, Thermal Conductivity and Mechanical Properties of Mg-3Al-0.3Mn Alloys.

The effects of La addition on the microstructure, thermal conductivity and mechanical properties of as-cast and as-extruded Mg-3Al-xLa-0.3Mn (x = 1, 3 and 5 wt.%) alloys were studied. The results showed that the thermal conductivity of the alloys increased with the addition of La element, which was due to the formation of the Al11La3 phases by consuming the solute Al and the added La element. The yield strength of the as-cast Mg-3Al-xLa-0.3Mn alloys increased with the increase in La concentration. The thermal conductivity of the as-extruded alloys was lower than that of as-cast counterparts owing to lots of defects generated in the process of hot extrusion deformation, particularly the grain boundaries. The anisotropy of thermal conductivity was discovered in the as-extruded alloys on account of the formation of texture. As the La content increases, the tensile strength and yield strength of the as-extruded alloys decreased gradually. In contrast, the elongation first increased and then decreased, resulting from the combined effect of the texture strengthening and second phase strengthening.