Microstructure Of La0 Research Articles

Extremely reduced loss tangent with retaining ultra high dielectric permittivity in Mg2+-doped La1.9Sr0.1NiO4 ceramics

An extremely reduced loss tangent while retaining ultrahigh dielectric permittivity can be successfully obtained in La1.9Sr0.1NiO4 ceramics by doping with Mg2+ ions. A single phase of La1.9Sr0.1NiO4 was detected in all the sintered ceramics, while the lattice parameters increased with increasing doping concentration, indicating that Mg2+ ions can enter the Ni2+ sites. A highly dense microstructure is achieved. Microstructural analysis revealed that Mg2+ ions disperse well in the microstructure of La1.9Sr0.1NiO4 ceramics. Interestingly, ultra–high dielectric permittivity of approximately 8.11 × 105 at 1 kHz is achieved in the La1.9Sr0.1Ni0.6Mg0.4O4 ceramic, while the loss tangent is significantly reduced by two orders of magnitude compared to the undoped La1.9Sr0.1NiO4 ceramic. The DC conductivity significantly decreased by three orders of magnitude. The giant dielectric responses are described by Maxwell–Wagner polarization and small polaron hopping mechanisms. Thus, the significant reduction in the loss tangent can be attributed to the significantly enhanced resistance of the grain boundaries.

Fabrication and characterisation of La<SUB align="right">0.8Sr<SUB align="right">0.2CrO<SUB align="right">3-ITO thermocouples for high-temperature sensing

La0.8Sr0.2CrO3-ITO thermocouples were successfully fabricated by screen printing. The La0.8Sr0.2CrO3 powder used for screen printing was obtained by the sol-gel method. The highest thermal voltage output was maintained at 270 mV at 1270°C. The microstructure of La0.8Sr0.2CrO3 and ITO electrode films were analysed by SEM. Thermoelectric response test was implemented to measure the performance of La0.8Sr0.2CrO3-ITO thermocouple by three times of thermal cycles. The results indicated that La0.8Sr0.2CrO3-ITO thermocouple showed good stability at high temperature.

Structure and microstructure of La0.8Ca0.05Ag0.15MnO3 material synthesized by sol-gel method

The La0.8Ca0.05Ag0.15MnO3 material was prepared by the sol-gel method, sintered at 800°C for 24 hours. The material is derived from the La0.8Ca0.2MnO3 material substituted by 15% Ag on the Ca-site. The substitution changed the lattice parameters, Mn-O bond length, and Mn-O-Mn bond angle. These can affect the transport of electrons from the material. The XRD data were analyzed using Rietveld refinement technique and show the material has a rhombohedral structure with the lattice parameters a, b, and c are 5.494, 5.494, and 13.33, respectively. The SEM data with SE mode show La0.8Ca0.2MnO3 material substituted by 15% Ag seen the existence of agglomeration and porous. Furthermore, the material has a high homogeneity, this is seen in SEM data with BSE mode. The EDX results show that the silver has been successfully substituted into the La0.8Ca0.2MnO3 matrix with the value at% for each element contained in the material close to value at% calculation.

Dependence of Syngas Composition on Microstructure of La0.8Sr0.2Cr0.5Mn0.5O3–δ Based Cathode for CO2 and H2O Co-Electrolysis

Ceramic materials with perovskite structure have attracted attention as possible redox stable, sulfur- and carbon tolerant cathode materials for solid oxide electrolysis cells 1,2. For example, composite cathode based on La0.8Sr0.2Cr0.5Mn0.5O3-δ (LSCM) are used for high temperature electrolysis of steam and co-electrolysis of steam and carbon dioxide 3,4. However, the limitation of electrochemical performance of electrolysis cell due to insufficient electrocatalytic activity can be a serious challenge 5. In this study, catalytically active nickel and copper nanoparticles were grown on the surface of A-site deficient LSCM via redox exsolution. Influence of water-gas shift reaction activity conditions of electrolysis and nanocatalyst properties on the outlet gas composition were evaluated. Electrolysis cells were prepared by sandwiching dense Zr0.89Sc0.10Ce0.01O2-δ (ScCeSZ) electrolyte layer between porous ScCeSZ layers and followed by wet impregnating of electrocatalytically active electrodes into the porous matrix. Impregnated salt mixture is decomposed at 400 °C, calcined and then sintered at 1400°C for 5 h. The thicknesses of the dense electrolyte and the porous scaffold were approximately 100 μm and 40 μm, respectively. Scanning electron microscopy, X-ray diffraction, FIB-TOF-SIMS and ICP-MS methods were used to characterize materials. Electrochemical characterization and analysis of outlet gas composition using gas chromatography was carried out at temperature range from 650 to 850 °C in various H2O, CO2, H2 and Ar inlet concentrations. As expected, the activity of composite cathode was greatly enhanced by the exsolved nickel and copper nanoparticles. For gas compositions the influence of water-gas shift (WGS) for nickel was greater than for copper. Thus, it has been demonstrated that both nickel and copper nanoparticles can enhance the electrolytic activity of the cathode for steam electrolysis and co-electrolysis of steam and carbon dioxide. Influence of water-gas shift reaction at co-electrolysis conditions and properties of nanocatalysts on the outlet gas composition were evaluated.

State-of-the-Art La0.6Sr0.4Co0.2Fe0.8O3-δ Cathode for SOFC: Microstructural and Electrochemical Properties

Solid Oxide Fuel Cells (SOFCs) have drawn much attention because they convert chemical energy into electrical energy efficiently in eco-friendly way. The performance of a SOFC depends on several combined factors in each cell compartments (i.e. anode, cathode and electrolyte). Especially the polarization resistance of the cathode becomes significant for intermediate temperature operations (500 – 700 °C). For this reason, the cathode reaction kinetics and influence of microstructure of state-of-the-art cathode materials have been extensively researched through comparative experimental studies and numerical simulations in the literature. Porous cathodes comprising mixed ionic-electronic conductors (MIEC) are commonly preferred in these energy conversion devices operating at intermediate temperature. They grabbed particular attention since the oxygen reduction reaction (ORR) is extended at the electrode/electrolyte interface, beyond the triple phase boundary (TPB) points. Earlier in our group, reaction kinetics of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) deposited by electrostatic spray deposition (ESD) technique was studied in two different microstructures, i.e; the coral and columnar-types [1-3]. Thanks to nanostructured microstructure features, one of the lowest polarization resistance (Rpol) values compared to literature was achieved. The present study concerns the influence of the thickness of columnar LSCF films on the area specific polarization resistance (ASR) of the cathode. Symmetrical cells of LSCF were deposited on dense Ce0.9Gd0.1O2-δ (CGO) electrolyte. The cathodes were consisted of double layer films of LSCF deposited sequentially by ESD technique as cathode functional layer (CFL) and by screen printing (SP) technique as current collecting layer (CCL) as shown in Figure 1. The thickness of CFL was varied between 0.5 and 18 μm by controlling the time of ESD deposition from 20᾿, 40᾿, 1h, 1h45᾿, 3h and 4h30’. Thickness of CCL was varied by SP from 20 to 50 μm. The resulting electrode thicknesses and microstructures were investigated by scanning electron microscope and microstructural parameters (porosity, specific surface area) were calculated by 3D reconstruction of the images obtained by FIB/SEM tomography. The electrode performance in terms of ASR as well as current constriction effects were monitored by electrochemical impedance spectroscopy (EIS). The results are discussed in terms of microstructure, adherence at the electrode/electrolyte interface, conductivity and optimized cathode performance. The hierarchical porous character of CFL is highlighted with macro porosity separating the columns and nano porosity within the columns [4]. The CCL provides a flatter surface than the CFL, thus improving the current collection by increasing the contact points between the surface and current collecting grid. We have shown that the electrochemically active layer in LSCF nanostructured columnar cathodes deposited by ESD concentrates on only a couple hundred nanometers away from the electrode/electrolyte interface [4]. One can conclude that the optimized films require at least 4-5 µm CFL thickness and 36 µm total thickness (CFL-CCL). In this geometry, the optimized ASR value of 0.065 Ω cm2 at 600 °C was achieved for double layer cathode characterized by a porosity amount of approximately 22 % and a specific surface area of 19 μm-1 with a columnar-type microstructure [4]. This ASR value is still amongst the highest specific surface area values achieved for SOFC cathodes. D. Marinha, C. Rossignol, E. Djurado, Influence of electrospraying parameters on the microstructure of La0.6Sr0.4Co.2Fe.8O3- d films for SOFCs, Journal of Solid State Chemistry 182 (2009) 1742–1748.D. Marinha, L. Dessemond, J.S. Cronin, J.R. Wilson, S.A. Barnett, E. Djurado, Microstructural 3D reconstruction and performance evaluation of LSCF cathodes obtained by electrostatic spray deposition, Chem. Mater. 23 (2011) 5340-5348.D. Marinha, J. Hayd, L. Dessemond, E. Ivers-Tiffée, E. Djurado, Performance of (La,Sr)(Co,Fe)O3−x double-layer cathode films for intermediate temperature solid oxide fuel cell, J. Power Sources. 196 (2011) 5084–5090.Celikbilek O., Jauffres D., Siebert, E., Dessemond L., Burriel M., Martin C.L., Djurado E., Rational Design of Hierarchically Nanostructured Electrodes for Solid Oxide Fuel Cells, J. Power Sources. 333 (2016) 72–82. Figure 1

Dependence of Syngas Composition on Microstructure of La0.8Sr0.2Cr0.5Mn0.5O3–δ Based Cathode for CO2 and H2O Co-Electrolysis

In this study, catalytically active nickel catalyst was grown via redox exsolution on the surface of A-site deficient La1-xSrxCr1-yMnyO3-δ based electrode with 6 % of Ni on B-site impregnated onto porous matrix made from Sc0.1Ce0.01Zr0.89O2- δ. Influence of A site deficiency on the electrochemical performance and effect of conditions of electrolysis and nanocatalyst properties on the outlet gas composition were studied.

Boron deposition and poisoning of La0.8Sr0.2MnO3 oxygen electrodes of solid oxide electrolysis cells under accelerated operation conditions

The effect of boron species from borosilicate glass sealant on the electrocatalytic activity and microstructure of La0.8Sr0.2MnO3 (LSM) oxygen electrodes is studied for the first time under accelerated solid oxide electrolysis cell (SOEC) operation conditions at 800 °C. The presence of volatile boron species has remarkable detrimental effect on the electrochemical activity of LSM oxygen electrode for the O2 evolution reaction (OER). After polarization at 200 mA cm−2 for 2 h, the electrode polarization and ohmic resistances increase rapidly from ∼40 and 1.2 Ω cm2 to 614 and 33 Ω cm2, respectively. Under the anodic polarization conditions, there is an accelerated Sr segregation and boron deposition preferentially occurs at the electrode/electrolyte interface, forming lanthanum borates and manganese oxide. Boron deposition and reaction is driven to the interface region due to the increased activity and energetics of lanthanum at LSM lattice sites at the electrode/electrolyte interface under anodic polarization conditions, accelerating the disintegration and delamination of the LSM electrode. The results indicate the potential detrimental effect of volatile boron on the electrochemical activity and stability of LSM oxygen electrodes of solid oxide electrolyzers.

Cr deposition on porous La0.6Sr0.4Co0.2Fe0.8O3 − δ electrodes of solid oxide cells under open circuit condition

The effect of Cr deposition and poisoning on the electrochemical activity and microstructure of La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) electrodes is investigated in detail under open circuit conditions at 900°C, 800°C and 700°C in the presence of a Fe–Cr alloy interconnect. The electrochemical performance of LSCF electrodes for the O2 reduction reaction (ORR) under solid oxide fuel cells (SOFCs) mode and for the O2 evolution reaction (OER) under solid oxide electrolysis cells (SOECs) mode is seriously degraded after exposure to Cr-containing air at open circuit voltage. SEM, XRD and Raman spectroscopy analyses reveal the formation of SrCrO4 phase and the deposition of a ~1μm thick Cr deposit layer on the outer surface of LSCF electrodes after exposure to Fe–Cr alloy interconnect at 900°C for 20h under open circuit conditions, greatly limiting the oxygen exchange and diffusion related processes. However, the magnitude of Cr deposition decreases significantly with the decrease in temperature. The results also confirm that the mechanism of Cr deposition on LSCF electrodes is a chemical process in nature that is initiated most likely by the nucleation reaction between surface segregated SrOx and gaseous Cr species.

Synthesis and microstructure of La1−xCaxCoO3 nanoparticles and their catalytic activity for CO oxidation

Perovskite nanoparticles of La1−xCaxCoO3 (x = 0, 0.2, 0.3, 0.5) were synthesized by the combustion method using polyvinyl alcohol (PVA) and corresponding metal nitrates. Microstructure of samples was characterized by high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) combined with x-ray diffraction (XRD). The nanoparticles were characterized by thermogravimetric and differential thermal analysis (TG-DTA) and BET (Brunauer–Emmet–Teller). A high surface area (15–21 m2 g−1) at low temperature (600 °C) of samples was obtained. The optimal preparative conditions were PVA/metals 2:1 by mole, pH = 3 and 80 °C for gel formation. Perovskites exhibit a good catalytic activity in total oxidation of CO at the low temperature (<250 °C) of reaction.

A Fundamental Study of Boron Deposition and Poisoning of La0.8Sr0.2MnO3 Cathode of Solid Oxide Fuel Cells under Accelerated Conditions

Borosilicate glass and glass-ceramics are the most common sealant materials for planar solid oxide fuel cells (SOFCs). This study focuses on the fundamentals of deposition and poisoning of volatile boron species from the borosilicate glass on the electrocatalytic activity and microstructure of La0.8Sr0.2MnO3 (LSM) cathodes under accelerated SOFC operation conditions, using EIS, SEM, FIB-SEM, HRTEM, NanoSIMS, XPS and ICP-OES. The presence of boron species poisons and deteriorates the electrochemical activity and stability for the O2 reduction reaction on the LSM cathodes. Boron deposition occurs randomly on the LSM electrode surface under open circuit but is driven to the electrode/electrolyte interface region under cathodic polarization conditions, resulting in the formation of LaBO3 and Mn2O3 and the disintegration of the LSM perovskite structure. The preferential boron deposition at the interface is most likely due to the increased activity of the highly energetic lanthanum at LSM lattice sites at the three phase boundary region under cathodic polarization conditions, accelerating the reaction rate between the gaseous boron species and energetic La. This study provides a fundamental insight into the boron deposition and its interaction with SOFC cathodes.

Interfaces in La1.89Ce0.11CuO4/Ba0.5Sr0.5TiO3/La0.88Sr0.12MnO3 heterostructures on (0 0 1) SrTiO3 substrates

High-quality La1.89Ce0.11CuO4/Ba0.5Sr0.5TiO3/La0.88Sr0.12MnO3 heterostructures grown on SrTiO3 enable a variety of electronic devices. The performance of such devices depends strongly on the interfacial microstructure of the heterostructures. Here, we use high-resolution transmission electron microscopy to reveal the structure and microstructure of La1.89Ce0.11CuO4/Ba0.5Sr0.5TiO3/La0.88Sr0.12MnO3 heterostructures. A step at the interface between La1.89Ce0.11CuO4 and Ba0.5Sr0.5TiO3 layers is found to have a height of about 1.36 nm. The interfacial structures on both sides of the step at the atomic level are revealed by image processing and image simulation. Major defects in the Ba0.5Sr0.5TiO3 and La0.88Sr0.12MnO3 layers are dislocations with a Burgers vector of a [1 0 0].

Transport properties and microstructure of La0.7Sr0.3MnO3 nanocrystalline thin films grown by polymer-assisted chemical solution deposition

Perovskite-based materials can be widely used in the aerospace and transportation field. Perovskite manganese oxides La0.7Sr0.3MnO3 (LSMO) thin films were grown on LaAlO3 (100) and Si (100) single crystal substrates by the polymer-assisted chemical solution deposition (PACSD) method. Electronic transport behavior, microstructure, and magnetoresistance (MR) of LSMO thin films on different substrates were investigated. The resistance of LSMO films fabricated on LaAlO3 substrates is smaller than that on the Si substrates. The magnetic field reduces resistance of LSMO films both on Si and LAO in the wide temperature region, when the insulator-metal transition temperature shifts to higher temperature. The low-field magnetoresistance of LSMO films on Si in low temperature range at 1 T is larger than that of LSMO films on LAO. However, the MR of LSMO film on LAO films at room-temperature is about 5.17 %. The thin films are smooth and dense with uniform nanocrystal size grain. These results demonstrate that PACSD is an effective technique for producing high quality LSMO films, which is significant to improve the magnetic properties and the application of automotive sensor.

Study of Pr and Pr and Co doped La2NiO4+δ as cathodes for La5.5WO11.25−δ based protonic conducting fuel cells

The mixed ionic-electronic conductor La2NiO4+δ was investigated as potential cathode material for protonic conducting solid oxide fuel cells (PC-SOFCs) based on La5.5WO11.25−δ electrolyte. Firstly the chemical compatibility between cathode and electrolyte phases (La2NiO4+δ and La5.5WO11.25−δ respectively) was studied. Then, the electrochemical properties of this cathode were improved by partially substituting La and/or Ni, specifically La1.5Pr0.5NiO4+δ and La1.5Pr0.5Ni0.8Co0.2O4+δ were considered. These two doped materials showed improved electrical conductivity and reduced polarization resistance, when tested as cathode in symmetrical cells. In a second step, the microstructure of La1.5Pr0.5Ni0.8Co0.2O4+δ was optimized by varying the firing temperature of the cathode. The performance of these mixed conductors is limited by medium frequencies associated processes while they show lower polarization resistances (Rp) than conventional composites based on La5.5WO11.25−δ and pure electronic conductors. La1.5Pr0.5Ni0.8Co0.2O4+δ cathode sintered at 1050 °C exhibits the best electrochemical performance on a La5.5WO11.25−δ-based PC-SOFC, achieving Rp = 0.62 Ω cm2 at 750 °C in wet air.

Influence of Firing Temperatures on Phase Formation and Microstructure of La0.92Mg0.18Fe0.90O3 Ceramics Synthesized via the Combustion Route

A novel combustion technique has been developed to synthesize La0.92Mg0.18Fe0.90O3 or LMF ceramics. The NH2CH2COOH was used as the fuel to accelerate the chemical reaction of raw materials. Thermogravimetric TG and differential thermal analysis DTA were used to estimate the calcination temperature in the range from 800 to 1000°C. The pure perovskite phase was obtained for the samples calcined at 900°C for 2 h. This calcination temperature was selected for the pellets sintered between 1000°C and 1200°C for 2 h. The effect of calcination and sintering temperatures on the phase and morphology evolution of perovskite LMF was investigated. The XRD patterns indicated that LMF exhibited orthorhombic perovskite structure. With increasing the firing temperatures, the lattice parameters and the unit cell volume changed only slightly; the average particle size and the average grain size tended to increase from 133 to 227 nm and 0.40 to 0.92 μm, respectively. The density of sintered ceramics changed between 3.19 and 3.37 g/cm3 depending on the sintering temperature.

Research on a New Synthesis Technology of La-Mg-Ni System Alloys and Microstructure of La0.67Mg0.33Ni3.0 Alloys

Abstract By choosing chemical reagents containing La, Mg, Ni element respectively as raw materials, the precursor of three-element composite metal oxides was prepared at first. With the experimental parameters optimized, research on preparation of La-Mg-Ni system alloys with a new synthesis technology based on co-precipitation and reduction-diffusion, and microstructure of La 0.67 Mg 0.33 Ni 3.0 alloys, was carried out. And the feasibility of this new synthesis technology has been verified. The results show that the alloys prepared through co-precipitation and reduction-diffusion have a multi-phase structure, their structure and ingredients are even, and their lattice distortion is small. In addition, the reducing process is relatively thorough and the content of oxygen is rare, achieving the expected results. The new synthesis technology is feasible, but it is necessary to optimize the process.

Effect of the reaction medium on the structure of the La1 − x Ca x MnO3 (x = 0–1) solid solutions prepared by the pechini method

The phase composition and microstructure of La1 − xCaxMnO3 (x = 0–1) materials prepared by the Pechini method from polymer-salt stocks were studied after testing these materials in methane oxidation. According to X-ray diffraction data, the reaction medium causes no significant changes in the samples, while high-resolution transmission electron microscopy indicates that the x > 0.3 samples are unstable. Under the action of the reaction medium, the perovskite structure of these samples undergoes partial decomposition accompanied by the formation of planar defects having a lower manganese content. The number and degree of segregation of these defects increase with increasing calcium content. The calcium oxide and manganese oxide phases as segregated nanoparticles are observed on the particle surface. These changes are caused by the decrease in the oxygen content of the manganites under the action of the reaction medium \( (T,P_{O_2 } ) \) , by the formation of vacancies, and by the variation of the charge of the manganese cations, as well as by the charge ordering tendency of the manganese cations. Therefore, the observed changes in catalytic activity under the action of the reaction medium for x > 0.3 can be due to perovskite decomposition accompanied by the formation of planar defects, the release of the manganese oxide and calcium oxide phases, and their subsequent sintering.

High‐Temperature Proton‐Conducting Lanthanum Ortho‐Niobate‐Based Materials. Part II: Sintering Properties and Solubility of Alkaline Earth Oxides

The sintering properties and microstructure of La1−xAxNbO4 powders (x=0, 0.005, and 0.02 and A=Ca, Sr, and Ba), prepared by spray pyrolysis have been investigated. Dense materials (&gt;97%) were obtained by conventional sintering at 1200°C and by hot pressing (25 MPa) at 1050°C, respectively. Homogeneous materials were obtained and the average grain size obtained by the two densification methods was ∼2.0 and ∼0.4 μm, respectively, for the 2% doped materials. Pure lanthanum ortho‐niobate (LaNbO4) showed a higher degree of grain growth. In the acceptor‐doped materials, secondary phases were observed to inhibit grain growth at 1200°C. At 1400°C or higher, molten secondary phases in the Ba‐doped materials resulted in severe grain growth, causing microcracking during cooling due to crystallographic anisotropy. A low solubility of AO (A=Ca, Sr, and Ba) in LaNbO4 is inferred from the presence of secondary phases, and 1 mol% solubility of SrO in LaNbO4 was found by electron microprobe analysis. The electrical conductivity in wet hydrogen of the materials demonstrated that the main charge carrier was protons up to 1000°C and reached a maximum value of ∼8·10−4 S/cm at 900°C.

Transmission electron microscopy study of epitaxial La0.8MnO3 thin films on SrTiO3

The structure and microstructure of La0.8MnO3 thin films on SrTiO3 substrates, fabricated by pulsed laser deposition at substrate temperatures of 873 K and 1073 K, have been studied by transmission electron microscopy. In both films, columnar growth morphology has been observed. The columnar grain size is found to increase with increasing substrate temperature. In the film deposited at a substrate temperature of 1073 K, there is only one rhombohedral phase. However, two phases, a rhombohedral one and an orthorhombic one, have been observed in the film deposited at 873 K.

Performance Improvement of (La,Sr)MnO3 and (La,Sr)(Co,Fe)O3-Type Anode-Supported SOFCs

Targets in the development of anode-supported or planar solid oxide fuel cells (SOFCs) are low operation temperatures, high durability, high reliability, high power density, and low production costs. During the past ten years steps have already been taken at Forschungszentrum Jülich to lower the operating temperatures while maintaining the power output. This was achieved by optimizing processing and microstructural parameters of the electrodes. This paper presents the latest results concerning performance improvement through variations of the processing route and the microstructure of La0.65Sr0.3MnO3 (LSM) and La0.58Sr0.4Co0.2Fe0.8O3−δ (LSCF)-type SOFCs. In the case of the LSM-type single cells, the following aspects relating to the electrochemical performance were investigated in more detail: (1) production of the anode substrate by tape casting versus warm pressing; (2) deposition of the anode functional layer (AFL) and electrolyte by screen printing versus vacuum slip casting; (3) use of noncalcined and non-ground YSZ for applying the cathode functional layer (CFL); and (4) sintering temperature of the CFL and cathode current collector layer (CCCL). In the case of LSCF-type cells, a systematic approach was initiated for optimizing the Ce0.8Gd0.2O2−δ (CGO) diffusion barrier layer: (1) deposition techniques of the CGO layer and (2) sintering temperature of the screen-printed CGO layer. Results have shown that certain modifications of the processing route led to a slightly lower electrochemical performance, whereas others did not affect the performance at all. Regarding LSCF-type SOFCs, a slight improvement of the performance was achieved by optimizing the sintering temperature of the CGO layer.

Temperature sintering effects on the magnetic, electrical and transport properties ofLa0.67Sr0.33MnO3/Nd0.67Sr0.33MnO3 composites

The microstructure, magnetic and electrical transport properties ofLa0.67Sr0.33MnO3/Nd0.67Sr0.33MnO3 composites are studied as a function of sintering temperature. At900 °C, the intergrain exchange couplings between the adjacent particles give rise to an increase inresistance. Raising the sintering temperature induces the formation of an interfacial phase near theLa0.67Sr0.33MnO3 and Nd0.67Sr0.33MnO3 grain boundaries as indicated in the XRD pattern and SEM image. At1100 °C, the formation of interfacial phases near the grain boundaries enhances the conductivity in thecomposite. Broad magnetoresistance across room temperature is observed in a composite sintered at1300 °C. This observation may be ascribed to the coexistence of multiphase in the composite whichleads to a decrease in resistance. The results suggest that sintering temperaturehas a prominent effect on the properties of the grain boundary, which plays animportant role in determining the electrical transport behaviour of the composites.