Perovskite-like Structure Research Articles

Layer Resolved Cr Oxidation State Modulation in Epitaxial SrFe0.67Cr0.33O3-δ Thin Films.

Understanding how doping influences physicochemical properties of ABO3 perovskite oxides is critical for tailoring their functionalities. In this study, SrFe0.67Cr0.33O3-δ epitaxial thin films were used to examine the effects of Fe and Cr competition on structure and B-site cation oxidation states. The films exhibit a perovskite-like structure near the film/substrate interface, while a brownmillerite-like structure with horizontal oxygen vacancy channels predominates near the surface. Electron energy loss spectroscopy shows Fe remains Fe3+, while Cr varies from ∼Cr3+ (tetrahedral layers) to ∼Cr4+ (octahedral layers) within brownmillerite phases and becomes ∼Cr4.5+ in perovskite-like phases. Theoretical simulations indicate that Cr-O bond arrangements and the way oxygen vacancies interact with Cr and Fe drive Cr charge disproportionation. High-valent Cr cations introduce additional densities of states near the Fermi level, reducing the optical bandgap from ∼2.0 eV (SrFeO2.5) to ∼1.7 eV (SrFe0.67Cr0.33O3-δ). These findings offer insights into B-site cation doping in the perovskite oxide framework.

Near-Infrared Persistent Luminescence of CaTiO3:Cr,Y for Imaging of Bone Implants Using Red-Light Illumination Instead of X-ray.

Near-infrared (NIR) persistent luminescence (PersL) materials have unique optical properties with promising applications in bioimaging and anticounterfeiting. However, their development is currently hindered by poor red-light-exciting ability. In this study, CaTiO3:Cr0.001,Y0.02 (CTCY) was synthesized with 650 nm-excited 772 nm NIR PersL. The Y3+ doping in the Ca2+ lattice plays a key role in the PersL property. A charge compensation mechanism was proposed, in which Cr3+ in the Ti4+ lattice was stabilized by Y3+-doping while oxygen vacancies were generated to store the excitation energy at the same time. A thermal ionization mechanism might elucidate the red-light-excited NIR PersL of CTCY, which benefits from the perovskite structure of CaTiO3. CTCY has 120 times more intense red-light-excited PersL than Zn3Ga2Ge2O10:Cr. Its potential applications in luminescence anticounterfeiting and bioimaging were demonstrated using a visible/NIR dual-channel PersL flower painting and a CTCY-labeled bone screw for in situ reactivable PersL imaging using red light illumination instead of X-ray, respectively. This study not only provides a new NIR PersL material but also will add to our understanding in developing other potential red-light- or even NIR-activable PersL materials with perovskite-like structures.

Study of the physical properties of BiFeO3 films obtained by RF sputtering using a homemade target

Ferroelectric materials have attracted significant attention in recent decades because they can be used in various electronic devices. BiFeO3 (BFO) has a perovskite-type ABO3 structure with antiferromagnetic and ferroelectric properties and a band gap within the visible light range, making it a promising candidate for use in sensors and solar cells. In this study, BiFeO3 thin films were grown by radio frequency (RF) sputtering using a homemade target and sintered at different times to evaluate the influence of sintering time on their physical properties. Its physical properties were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy. These results revealed that all films maintained a perovskite-like structure with rhombohedral and bismuth-rich secondary phases (Bi2O2.33). Atomic force microscopy (AFM) and piezoresponse force micrography (PFM) images depicted the impact of sintering time on surface roughness and ferroelectric domain reorientation. The optical properties, such as n, k, and the band gap of all samples, were obtained using reflection-transmission spectroscopy. The photoresponse under dark, visible and UV illumination were evaluated on BFO films grown over glass-FTO substrate.

Novel proton-conducting hexagonal perovskites Ba7In6–xYxAl2O19 for solid oxide fuel cells

The solid solution Ba7In6–xYxAl2O19 (0≤x≤0.25) with a hexagonal perovskite-like structure was prepared by the solid-state route. The introduction of yttrium was accompanied by an increase in lattice parameters. The total conductivity as a function of pO2 and T was measured at different humidity. The partial conductivities were found by transport number measurements and were fitted based on the defect formation model. Oxygen-ion and proton conductivities were found to increase with Y3+ content as a result of an increase in cell volume and free volume, which was accompanied by a decrease in the activation energy of both oxygen-ion and proton conductivity. Oxygen-ion conductivity and proton conductivity dominated below 500 °C in dry (pH2O=3.5×10−5 atm) and in wet (pH2O=1.92×10−2 atm) conditions, respectively. Doping makes it possible to increase proton conductivity by an order of magnitude (500 °C) and significantly increase the proton transport numbers.The prepared phases exhibited excellent chemical stability during thermal treatment in carbon dioxide (pCO2=1 atm).

Structural distortion-induced low-temperature dielectric dispersion in lanthanide titanate pyrochlores

Rare-earth titanate pyrochlores have attracted significant attention for their unique magnetic frustration; however, research on the origin of low-temperature dielectric dispersion and the relationship between dielectric properties and structure lags far behind. Here, by systematically investigating the dielectric properties of representative rare-earth titanates R2Ti2O7 (R = La, Nd, Sm, Er, Yb, and Lu), we demonstrate that R2Ti2O7 with a cubic pyrochlore structure exhibits low-temperature dielectric dispersion behavior, while the other compounds with a monoclinic perovskite-like layered structure possess no dispersion behavior but excellent temperature-stable dielectric property. The dielectric dispersion in cubic pyrochlores arises from the structural distortion. Furthermore, the existence of structural distortion is affirmed by the anomalous phonon softening of A1g Raman mode around the dielectric dispersion temperature, and the origin of the structural distortion is attributed to anharmonic phonon–phonon interactions induced by intrinsic vacant oxygen at Wyckoff 8a sites. In addition, with increasing ionic radius from R = Lu to Sm, the increased lattice parameter leads to varied bond length and bond angle of Ti-O(1)-Ti, which strengthens the local lattice distortion of TiO(1)6 octahedra and thus enhances diffusion degree of dielectric dispersion. On the other hand, the absence of intrinsic vacant oxygen site hardly gives rise to the local structural distortion and thus no dielectric dispersion in monoclinic R2Ti2O7. Our work not only clarifies the mechanism of dielectric dispersion but also gives a comprehensive perspective on the structure–property relationship of rare-earth titanates R2Ti2O7, and thus lays a solid foundation for further work on related materials.

Phase transition, structural and magnetic parameters of vanadium-substituted Bi0.9Sm0.1FeO3 multiferroic ceramics

ABSTRACT The inorganic multiferroic compounds Bi0.9Sm0.1Fe1 − x V x O3 (x = 0.0, 0.015, 0.03, and 0.045) were prepared by the solid-state reaction method. X-ray diffraction analysis confirmed the rhombohedral perovskite-like structure with minor traces of the impurity phases Bi2Fe4O9 and Bi25FeO40. The lattice parameters a and c, and the volume of the hexagonal unit cell were extracted from the X-ray diffraction data and found to increase as the V5+ content is increased. The average crystallite size was estimated to be in the range 380–415 Å. Fourier transform infrared spectroscopy confirmed the rhombohedral perovskite-like structure via the vibration bands of the octahedral FeO6 group observed between 410 and 570 cm−1. A differential scanning calorimeter was used to record the thermal scans which revealed that the compounds have undergone crystalline phase transitions at temperatures in the range 300–320°C. A 4.5% V + 5 substitution has shifted the transition peak by 20°C. The magnetic hysteresis loops taken at room temperature with a vibrating sample magnetometer revealed the ordinary ferromagnetic behavior. The V5+ substitution enhanced the remanent magnetization, but the magnetic coercivity was found to fluctuate around an average value of about 1000 Oe. The compound Bi0.9Sm0.1Fe0.955V0.045O3 exhibited the maximum remanent magnetization.

Photoluminescence Study of Undoped and Eu-Doped Alkali-Niobate Aluminosilicate Glasses and Glass-Ceramics.

In this study, the photoluminescence (PL) behavior of two aluminosilicate glass series containing alkali-niobates ranging from 0.4 to 20 mol% was investigated. The glasses exhibit an intense visible emission centered at ~18,400 cm-1 for the peralkaline series and at higher energies (~19,300 cm-1) for the metaluminous glasses. However, the photoluminescence emission intensity varies significantly with the niobate content and the bulk chemistry. PL and fluorescence lifetime measurements indicate that the broad emission bands result from the overlap of different niobate populations, whose distribution changes with niobate content. The distinct PL behavior in the two glass series was related to the structural evolution of the niobate units upon niobium addition. An enhancement of the visible emission was observed for a higher fraction of distorted [NbO6] units. Eu-doping was carried out as a structural probe of the glass network, and also to determine if these glasses could be used as potential rare earth element (REE) activators. The crystal field strength around Eu ions is strongly dependent on the bulk chemistry and the niobate content. Furthermore, the peralkaline series showed energy transfer from the host [NbO6] to Eu3+, confirming the feasibility of exploring niobate glasses and glass-ceramics as lanthanide ion-activated luminescent materials. In addition, glass-ceramics (GCs) containing alkali-niobate phases with a perovskite-like structure were developed and studied to verify the optical performance of these materials. It was verified that the bulk chemistry influences crystallization behavior, and also the photoluminescence response. The transparent GC from the metaluminous series exhibits a quenching of the Eu3+ emission, whereas an enhanced emission intensity is observed for the peralkaline GC. The latter shows a strong excitation-dependent PL emission, suggesting energy transfer and migration of electronic excitation from one Eu population to another. Additionally, Eu3+ emissions arising from the D15 and D25 excited states were observed, highlighting the low phonon energy achievable in niobo-aluminosilicate hosts.

Construction of energetic metal-organic frameworks based on 5-aminotetrazole

Metal-Organic Frameworks (MOFs) have recently gained prominence as a novel class of energetic materials, owing to their systematic design and the ability to fine-tune properties such as energy content, sensitivity, and thermal stability. In this study, two new MOFs namely Cd(5-AT)3NH2(CH3)2+(1) and Zn(5-AT)(AMP) (2) (5-HAT = 5-aminotetrazole) were prepared under solvothermal conditions using 5-aminotetrazole as the high-nitrogen energetic ligand. X-ray single crystal diffraction analysis revealed that compound 1 possess an ABX3-type perovskite-like structure, whereas compound 2 forms a two-dimensional layer. The high thermal stability of both compounds were confirmed through thermogravimetry (TG) and differential scanning calorimetry (DSC). Their constant-volume combustion heat (ΔcU) was first determined by oxygen-bomb calorimetry and then the standard molar enthalpy of formation (ΔfHo) was calculated. Furthermore, both compounds demonstrated great detonation properties and low sensitivity, showing their potential application as new explosive materials (EMs).

Efficient broad-band NIR-II emitting phosphor Mg4Ta2O9: Ni2+ with satisfactory thermal stability of luminescence

The applications of near-infrared (NIR) spectroscopy in the fields of medicine and food safety require efficient and compact NIR light sources, for example, NIR phosphor converted light-emitting diodes (pc-LEDs). In recent years, Ni2+ has become one of the main activators for its broadband NIR-II (1000–1700 nm) emission under ultraviolet or visible light excitation. However, two important effects (Concentration quenching which decreases the emission intensity and temperature quenching which decreases the adaptability of phosphor in high-power applications) seriously hinder the development of Ni2+ doped NIR-II emitting phosphors. It is an urgent and important task to restrain both concentration and thermal quenching of the Ni2+ luminescence to develop an efficient NIR-II emitting phosphor. Here, novel NIR-II emitting Mg4Ta2O9: Ni2+ phosphors with perovskite-like structure were synthesized and investigated. In Mg4Ta2O9, the quenching concentration of Ni2+ is as high as 0.045. This is a relatively high value for Ni2+ activated NIR-II emitting phosphors. Mg4Ta2O9: 0.045Ni2+ presents broadband emission (1100–1700 nm, the full width at half maximum (FWHM) = 218 nm) with internal and external quantum efficiency of 64.2% (IQE) and 7.2% (EQE), respectively. The phosphor exhibits excellent luminous thermal stability (at 423 K, it keeps 84.85% of initial intensity at room temperature). High structure stiffness of Mg4Ta2O9 is responsible for the high quenching concentration and desirable luminous thermal stability. This work developed an efficient NIR-II emitting phosphor which exhibits desirable thermal stability of luminescence. Theoretically, this work points out a direction for future development of efficient NIR-II emitting phosphors, selecting an inorganic compound with high structural rigidity as the host for Ni2+ doping.

Ultra-high piezoelectric properties and ultra-high Curie temperature of Li/Ce-doped La2Ti2O7 ceramics.

The demand for ultra-high-temperature piezoelectric sensors in industrial applications has witnessed a rapid upsurge. In this study, the piezoelectric properties of La2Ti2O7 (LTO) piezoelectric ceramics with a perovskite-like layered structure were enhanced by doping with Li/Ce ions. It was found that a remarkable 300% enhancement in the piezoelectric constant (d33) value was achieved in Li/Ce-doped LTO ceramics compared to their pristine counterparts, reaching 6.4 pC N-1 at room temperature with an ultra-high Curie temperature of 1408 °C. After annealing at 500 °C, the d33 value of the samples can be further improved to 7.4 pC N-1. Moreover, temperature-dependent resistivity measurements indicate that even at 1000 °C, the ceramics exhibit a high resistivity of 8.9 × 105 Ω cm. By combining X-ray diffraction, Raman spectra, transmission electron microscopy and piezoresponse force microscopy data, the enhanced piezoelectricity of the ceramics is attributed to local heterogeneity induced by Li/Ce doping. Our results unequivocally demonstrate the suitability of modified LTO ceramics for ultra-high-temperature piezoelectric applications.

Self-powered humidity sensors based on zero-dimensional perovskite-like structures with fast response and high stability.

With the rapid development of technology, the development of self-powered sensors has garnered significant attention. The importance of monitoring humidity has grown significantly in various technological contexts, from environmental monitoring to biomedical applications. In this work, we have fabricated a low-cost and self-powered humidity sensor using zero-dimensional perovskite-like structures. Switching tests at different relative humidity levels have shown that the zero-dimensional perovskites have visible coloration at high humidities and discoloration upon reducing the humidity. The humidity sensor was fabricated by spin coating the zero-dimensional perovskites on a patterned fluorine doped tin oxide (FTO) substrate and the sensor not only shows high response values of around 500 mV and few micro amperes of short circuit current densities, but also shows good cycling performance and stability. Also high selectivity to humidity is observed in comparison to different gases and volatile organic compounds. The high selectivity to humidity arises due to the fact that the exclusion of MAI from the MA4PbI6 strucuture does not happen with all the other analytes which has been confirmed from the XRD studies. In addition, due to the low temperature fabrication they can be deposited on flexible substrates and the sensor displayed excellent resistance to bending and durability. Furthermore, the study explored the humidity monitoring capabilities of this sensor, revealing an outstanding response performance to human respiration. This observation suggests that the sensor holds significant potential for practical applications in the monitoring of human health and environmental conditions. This work paves the way for developing organic-inorganic hybrid perovskite materials for self-powered sensing applications.

Cryogenic magnetocaloric effect of the CaErAlO4 compound

The magnetism and magnetocaloric effect (MCE) of some rare-earth (RE)-based oxides have attracted special attention due to their interesting physical and chemical properties, such as easy fabrication and high chemical stability. In this paper, the CaErAlO4 polycrystal compound synthesized by the high-temperature solid-state method manifests the considerable second-order reversible MCE near the temperature of liquid helium. This compound crystallizes in the perovskite-like K2NiF4-type structure with the space group of I4/mmm. The negative paramagnetic Curie temperature suggests that antiferromagnetism is dominant in the material and the moderate magnetization is mainly contributed by the ferromagnetic interaction in the sample. The measured isothermal magnetic entropy changes (∆SM) at 3 K are 14.3 and 22.9 J/kg K under 0–20 and 0–50 kOe field changes, respectively. They are greater than those of most RE-based oxides. Our results indicate that the CaErAlO4 compound is a promising candidate for cryogenic magnetic refrigeration.

Effect of scandium atoms substitution on the two-slab structure of scandate BaGd2Sc2O7

Tetragonal crystal structure (space group P42/mnm (No 136)) of the isovalently substituted BaGd2Sc2-xInxO7 phase with x = 0.5 was determined by X-ray powder diffraction methods. The crystal structure of BaGd2Sc1.5In0.5O7 consists of two-dimensional perovskite-like blocks with a thickness of two slabs of (Sc,In)O6 octahedra connected by vertices. A slab of GdO9 polyhedra is located between the blocks. There are no direct (Sc,In) – O – (Sc,In) connections between the octahedra of adjacent blocks. They are "stitched" to each other with the help of – O – Gd – O – bonds. Ba atoms are arranged only in the cubooctahedral voids of the perovskite-like block and their coordination number is 12. Analysis of the crystal chemical characteristics of BaGd2Sc2O7 and BaGd2Sc1.5In0.5O7 showed that upon the isovalent substitution of Sc atoms by large In atoms in slab perovskite-like structure leads to increase of the deformation degree of (Sc,In)O6 octahedra, GdO9 interblock polyhedra, increase in average (Sc,In) – O bond length and a decrease the degree deformation of BaO12 cuboctahedrons. Such changes lead to the destabilization of the slab perovskite-like structure and determine the limitation of the area of BaGd2Sc2-xInxO7 solid solutions and the absence of BaGd2In2O7 compound.

Effects of ion occupancy and polarizability on the crystal structure and microwave dielectric properties of CaEuCO4 (C[dbnd]Ga, Al) ceramics

CaEuCO4 (CGa, Al) microwave dielectric ceramics were produced through a solid-state reaction. Orthorhombic olivine CaEuGaO4 (pnma) exhibits a lower permittivity (εr = 9.7), a higher quality factor (Q × f = 82,049 GHz), and a larger negative resonant frequency temperature coefficient (τf = −54.6 ppm/°C). CaEuAlO4, which has a similar chemical formula, exhibits a perovskite-like structure (I4/mmm, K2NiF4-type), and its microwave dielectric properties are εr = 18.9, Q × f = 43,132 GHz, and τf = −1.6 ppm/°C. The difference in their structures is mainly caused by the properties of the Ga (III) atom. The difference in their dielectric properties can be proved to be affected by the “rattling” effect of Eu3+ through the bond valence theory. The relationship between the covalence (fc) and the bond strength (S) was investigated, and the higher bond strength might be the main reason for the higher Q × f in CaEuGaO4 ceramic.

Ultra-high Curie temperature transparent piezoelectric Bi doped Ca2Nb2O7 single crystals

Ca2Nb2O7 is a promising material for high-temperature piezoelectric applications due to its ultra-high Curie temperature, which makes it a suitable candidate for use in harsh environments. However, their piezoelectric performance needs improvement. Here, through chemical engineering methods, we have successfully grown Bi3+ doped Ca2Nb2O7 single crystals using the optical floating zone technique. The Ca1.94Bi0.06Nb2O7 single crystals achieved better high-temperature stability, transparency and a higher piezoelectric constant of 12.8 pC/N at 298 K and 20.0 pC/N at 660 K. In addition to the dopant effects, mechanisms for enhancing the piezoelectric properties of perovskite-like layer structure (PLS) materials have been identified, highlighting the significant contribution of the NbO6 octahedron and interlayer ions. These findings offers valuable insights into improving the performance of PLS materials, which is crucial for promoting their practical applications as high-temperature lead-free piezoelectric materials.

One-Step Sol-Gel Facile Synthesis and 3D Nanoscale Morphology Investigation of Bi0.5Na0.5TiO3-BaTiO3 Thin Films

Abstract: Bismuth sodium titanate, denoted as Bi0.5Na0.5TiO3-BaTiO3 (BNT-BT), possessing a perovskite-like structure, has emerged as a highly prospective material in recent years. It is considered a prime contender for replacing PZT-based compounds due to its exceptional piezoelectric and ferroelectric properties, coupled with the presence of loosely bound pairs of chemically active electrons. This study delves into the micromorphological properties of BNT-BT thin film electrodes, fabricated using sol-gel spin-coating and subsequent annealing processes. Employing Atomic Force Microscopy (AFM), comprehensive 2D and 3D topographical maps were acquired, enabling the extraction of pivotal parameters crucial for surface characterization. Notably, the investigation encompasses Minkowski Functionals, which encompass normalized Minkowski volume, boundary, and connectivity analyses. In conjunction, various roughness parameters, encompassing arithmetic mean height, maximum peak height, maximum valley depth, arithmetic mean depth, and the ten-point height parameter, were quantified across these analyses to facilitate a comprehensive comparison of surface morphologies among distinct samples. The morphological analysis outcome underscores the potential for elucidating material performance through microstructural shape and quantitative roughness evaluation of respective surfaces. This holds significant promise for applications such as predictive assessment of functional behavior, including industrial quality control during sample manufacturing processes.

Dependence of the formation of the five-layer Aurivillius phase on the chemical prehistory of the Initial composition

Materials with a layered perovskite-like structure of the Aurivillius phase type are important for such fields of technology as magnetoelectronics and photocatalysis. The paper describes the features of phase formation during the synthesis of nano- and macrocrystalline materials based on the Bi6Fe2Ti3O18/ 8 compound with the five-layer Aurivillius phase structure. Samples were characterized by powder XRD, DSC/TG, dilatometry, SEM/EDX. The temperatures of the beginning of formation, the Curie point, the beginning of decomposition and activation of sintering of the obtained materials, as well as the value of the linear thermal expansion coefficient were determined. The technological possibility of controlling the dispersion of the obtained materials by changing the synthesis conditions is shown. Ill. 5. Ref. 20. Tab. 1.

Effect of Pr3+ Addition on the Electrical Properties of 0.94(Bi0.5Na0.5)TiO3-0.06(Ba0.9Ca0.1)TiO3 Ceramic Obtained by Pechini Method

The influence of Pr3+ addition on the structure and electrical properties of (Bi,Na)TiO3-(Ba,Ca)TiO3 solid solution was investigated. In this work, 0.94(Bi0.5−xNa0.5)TiO3-0.06(Ba0.9Ca0.1)TiO3:xPr3+ (BNBCT6:xPr) with x = 0, 0.1, 0.3, 0.5, and 0.7 mol% ceramics were prepared via a polymeric complex synthesis (Pechini method). Optimal sintering parameters were chosen in order to obtain dense ceramic microstructures. X-ray diffraction confirmed the presence of a perovskite-like structure in all the synthetized powders and sintered samples. As Pr3+ content increased, a large reduction in grain size was observed. BNBCT6:xPr ceramics showed a phase transition from the field-induced ferroelectric to the relaxor phase at ~ 110 °C and a local maximum around 250 °C. Dielectric permittivity was reduced as Pr3+ doping increased. For x = 0.5 mol%, maximum piezoelectric values (d33 = 115 pC/N, − d31 = 27 pC/N, kp = 25%, and kt = 34%) were obtained, while for x = 0.7 mol%, ferroelectric characteristics (Pr = 14 µC/cm2, and Ec = 34.7 kV/cm) were enhanced. Bulk conductivities extracted from the impedance spectra for BNBCT6:xPr were low, consistent with the insulating characteristic of (Bi,Na)TiO3. The achieved electrical properties suggest that BNBCT6:xPr ceramics are a potential candidate for energy transition applications.

Numerical simulation and experimental study of methyl ammonium bismuth iodide absorber layer based lead free perovskite solar cells.

Recent years have witnessed a tremendous surge in the design and fabrication of lead-(Pb) free perovskite or perovskite-like materials for the construction of perovskite solar cells. The simulation and fabrication of Pb free perovskite-like structures based perovskite solar cells are of great significance. In present study, we have simulated methyl ammonium bismuth iodide (MA3Bi2I9) based perovskite solar cells using solar cell capacitance software (SCAPS). The thickness of the electron-transport layer, hole-transport layer and absorber layer were optimized via SCAPS. The simulated perovskite solar cells (FTO/TiO2/MA3Bi2I9/spiro-OMeTAD/Au) with optimized conditions demonstrated good power conversion efficiency of 14.07% with reasonable open circuit voltage of 1.34 V via SCAPS. In further studies, we also fabricated perovskite solar cells under controlled humidity which showed power conversion efficiency of 1.31%.

Preparation and electrochemical stability of Co-doped La1.5Sr0.5Ni1−xCoxO4+δ cathode materials

A series of Co-doped La1.5Sr0.5Ni1−xCoxO4+δ cathode materials (x =0, 0.2, 0.4 and 0.6) were synthesized by sol-gel method and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), coefficient of thermal expansion (CTE) measurement and scanning electron microscope (SEM). The results suggest that all La1.5Sr0.5Ni1−xCoxO4+δ samples have a single pure phase with the perovskite-like structure and the doping with the Co element can increase the CTE value. Using La1.5Sr0.5Ni1−xCoxO4+δ as the cathode materials in the solid oxide fuel cell (SOFC), their electrical conductivity and electrochemical impedance spectroscopy were measured. The results indicate that the conductivity increases with the increase of Co doping amount and the La1.5Sr0.5Ni0.6Co0.4O4+δ sample with x = 0.4 displays the highest conductivity of 51.21 S/cm at 800 °C; however, a higher content of Co (x > 0.4) leads to a decrease of the conductivity. In addition, La1.5Sr0.5N0.6Co0.4O4+δ exhibits the lowest polarization resistance of 4.180 Ω·cm2 in electrochemical impedance spectrum at 700 °C, displaying its excellent electrochemical properties as the cathode materials.