Single Perovskite Phase Research Articles

Assessing the improved luminescence of SrCe1-xSmxO3 perovskite by concentration controlled extra oxidizer substitution

Strontium cerate perovskite nano phosphors when doped with rare earth elements show improved functional properties such as electrical conductivity and photoluminescence. Electrical conductivity investigations on doped strontium cerates have been studied widely over decades for application in electrochemical cells, hydrogen sensors, hydrogen extractors, etc. But only minimal research has been developed in the amelioration of photoluminescence in rare earth-doped strontium cerates. In the present study, samarium-doped strontium cerate perovskite nanophosphors were considered for utilization in optoelectronic applications. The perovskites SrCe1-xSmxO3 (x = 0.01,0.02,0.03) were prepared via a low-temperature gel combustion approach with citric acid as chelating agent and ammonia solution as an extra oxidizer. The influence of concentration variation on the evolution behaviour of the crystalline phase as well as the luminescence characteristics of ceramic powders are investigated using X-ray diffraction and Photoluminescence characterization techniques. Experimental results indicate that the calcinating temperature of 1223 K in gel combustion synthesis, much lower than the conventional solid-state reaction is only needed for the single-phase perovskite formation. Also, a comparison study of the luminescence behaviour by replacing internal constituent extra oxidizer ammonia solution with ammonium nitrate is observed in this study, and conditions for maximum luminescence intensity are hence discussed. The observed results on photoluminescence studies indicate that an enhancement in the luminescence intensity of SrCe0.98Sm0.02O3 occurred when we replaced extra oxidizer ammonia solution with ammonium nitrate. Thus, a bright orange-scarlet red emitting perovskite nano phosphor SrCe0.98Sm0.02O3 by the later technique can be synthesized and can act as an inevitable red phosphor coating the chip in LEDs, which can be a great revolution in energy savings applications.

Fluorine Anion-Doped Ba0.6Sr0.4Co0.7Fe0.2Nb0.1O3-δ as a Promising Cathode for Protonic Ceramic Fuel Cells

The widespread application of protonic ceramic fuel cells is limited by the lack of oxygen electrodes with excellent activity and stability. Herein, the strategy of halogen doping in a Ba0.6Sr0.4Co0.7Fe0.2Nb0.1O3-δ (BSCFN) cathode is discussed in detail for improving cathode activity. Ba0.6Sr0.4Co0.7Fe0.2Nb0.1O3-x-δFx (x = 0, 0.05, 0.1) cathode materials are synthesised by a solid-phase method. The XRD results show that fluorine anion-doped BSCFN forms a single-phase perovskite structure. XPS and titration results reveal that fluorine ion doping increases active oxygen and surface adsorbed oxygen. It also confines chemical bonds between cations and anions, which enhances the cathode’s catalytic performance. Therefore, an anode-supported single cell with the configuration of Ni-BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb)|BZCYYb|Ba0.6Sr0.4Co0.7Fe0.2Nb0.1O3-0.1-δF0.1 (BSCFN-F0.1) achieved a high peak power density of 630 mW cm−2 at 600 °C. Moreover, according to the symmetrical cell test, the BSCFN-F0.1 electrode demonstrated a superb stability for nearly 400 h at 600 °C. This work focuses on the influence of fluorine anion incorporation upon the performance of cathode materials. It also analyses and discusses the effects of different fluorine ion incorporation amounts to occupy different oxygen positions.

Development of titanium-doped SmBaMn2O5+δ layered perovskite as a robust electrode for symmetrical solid oxide fuel cells

It is a big challenge ahead of finding a symmetric electrode material that optimally works as both anode and cathode, with excellent structural and chemical stability and high catalytic activity. Herein, we propose a high-performance symmetric electrode material, SmBaMn1.9Ti0.1O5+δ (SBMTi), with a single A-site layered perovskite phase in both reducing and oxidizing atmospheres. Owing to the high binding energy, titanium doping can enhance the structural stability and improve the catalytic activity to the hydrogen oxidation and oxygen reduction processes. The simple Ti-doping strategy enables a dramatic reduction in stoichiometric oxygen change upon oxidizing and reducing atmosphere alternation, and a considerable decrease in thermal expansion coefficient. The symmetrical cell with SBMTi electrode can provide a maximum power density of 603 mW cm−2 at 900 °C, and shows a relatively stable thermal-cycle and atmosphere alternation performance. The developed SmBaMn1.9Ti0.1O5+δ shows great potential as symmetric electrode in symmetrical solid oxide fuel cells.

Thermal, structural and optical properties of Pb1−x La x TiO3 prepared using modified sol–gel route

Abstract La doped lead titanate ceramic compositions Pb1−x La x TiO3 (PLT) for x = 0.0, 0.05, 0.1, 0.2 and 0.3 were synthesized by an acrylic acid modified sol-gel route. The microstructure, surface morphology, and optical properties of the resulting compositions were studied by using TGA, X-ray diffraction, Raman Spectroscopy, and UV–Vis spectroscopy. It was found that the acrylic acid acts as a strong gelling agent and the organic residue gets removed completely below 450 °C. Very smooth ceramic powders characterized by single perovskite phase were obtained. A reduction in the tetragonality ratio from 1.0698 to 1.0033 was observed with increasing La content from x = 0.0 to x = 0.3. The effect of reduced tetragonality was corroborated by the peak shift of soft modes in Raman spectra and approximately 2 cm−1 downshift of E(TO1) mode was observed for each atomic weight percent La addition in lead titanate. The average grain size was found decreasing marginally with the increasing La content in PLT. Using the UV–vis data, a slight but systematic increase in the direct absorption edge (band gap) from 3.155 eV to 3.234 eV was observed with increasing La content in the PLT compositions.

Structure, magnetic, and photocatalysis of La0.7Sr0.3MO3 (M = Mn, Co, and Fe) perovskite nanoparticles: Novel photocatalytic materials

The present study, La0.7Sr0.3MO3 (M = Mn-, Co-, and Fe-), perovskite, has successfully been synthesized via co-precipitation and sol–gel auto-combustion. XRD, SEM, and EDX characterized the prepared samples. XRD and SEM showed that the as-prepared La0.7Sr0.3MnO3 and La0.7Sr0.3CoO3 have multiphase. La0.7Sr0.3FeO3, in comparison, is nanosized, has a single-phase perovskite, and has a rather homogenous particle size distribution. Additionally, EDX mapping analysis shows that all pieces are distributed uniformly. According to X-ray diffractometer results, all calcined powders contain 100% LSF, more than 15% perovskite phase of LSC, 47% LSM, and other secondary phases, such as cobalt oxide. Aِt room temperature and magnetic field of ± 20 kG, La0.7Sr0.3MnO3 exhibited weak ferromagnetic behavior in a low magnetic field, whereas diamagnetic behavior was seen in a high magnetic field. La0.7Sr0.3FeO3 samples behave as strong ferromagnetic. On the contrary, the photodegradation of La0.7Sr0.3MnO3 is 99% compared to 75% and 91% for other samples under UVC lights of wavelength = 254 nm. The degradation rate for La0.7Sr0.3MnO3 is 0.179 higher, about 3.25 and 2.23, than the other samples. A La0.7Sr0.3MnO3 nanocomposite performs as a photocatalyst to enhance the efficiency of methylene blue photodegradation. This study boosts good UVC photocatalysts with high efficiency for different kinds of dyes. Hence, the catalyst possessed high stability and efficiency for continuous wastewater treatment.

Growth and thermal stability of Sc-doped BaZrO3 thin films deposited on single crystal substrates

Thin films of BaZr1-xScxO3-x/2, (0 ≤ x ≤ 0.64), well known as proton conducting solid electrolytes for intermediate temperature solid oxide fuel cell, were deposited by magnetron sputtering. X-ray diffraction analysis of the as deposited films reveals the presence of single-phase perovskite structure. The films were deposited on four different substrates (c-Al2O3, LaAlO3〈100〉, LaAlO3〈110〉, LaAlO3〈111〉) yielding random, (110)- or (100)-oriented films. The stability of the as-deposited films was assessed by annealing in air at 600 °C for 2 h. The annealing treatment revealed instabilities of the perovskite structure for the (110) and randomly oriented films, but not for (100) oriented film. The instability of the coating under heat treatment was attributed to the low oxygen content in the film (understoichiometry) prior annealing combined with the surface energy and atomic layers stacking along the growth direction. An understoichiometric (100) oriented perovskite films showed higher stability of the structure under an annealing in air at 600 °C.

Multiferroic properties in Fe-site engineered PbFe1/2Nb1/2O3 with distinct antisymmetric spin interaction

Multiferroic Fe-site engineered lead iron niobate [Pb(Fe1/2Nb1/2)O3, PFN] was prepared by partially substituting Fe with Ni, Co, and Cr, which comprise distinct Bohr magnetons, to investigate the effect of the variation in spin configurations on magnetic and multiferroic properties. All the studied compositions exhibited a single-phase perovskite structure, wherein the lattice constant decreased with increasing substitutions. The inherent ferroelectric order was preserved when Ni or Co ions were introduced, while the introduction of Cr made the samples too lossy, which prevented the verification of the possible ferroelectricity. Substitution of Fe with different transition metals in PFN, which is originally paramagnetic at room temperature, resulted in oriented spin configurations that led to distinct magnetic orders: soft ferromagnetic, hard ferromagnetic, and antiferromagnetic orders for Ni, Co, and Cr, respectively. This distinction mainly stems from the interspin distance and the spin moment, both of which are important factors during the spin exchange interaction. The interspin distance of pristine and Cr-substituted PFN is too long and short, respectively, to induce ferromagnetic properties. Moreover, at room temperature, magnetic-field-dependent magnetoelectric coupling was observed only for the Ni- and Co-substituted PFN owing to their asymmetric spin configuration. This research could lead to a general method for modulating the magnetic properties of multiferroic perovskite oxides.

Unprecedented investigation on luminescence property of proton conductive samarium incorporated barium cerate nanoparticles

Single phase perovskite structured BaCe0.98Sm0.02O2.99 (BCS) were synthesized through solution-combustion method followed by calcination in air atmosphere. Orthorhombic BCS perovskite crystal formation was confirmed by XRD analysis. Sm3+ incorporation causes emissions with a dominant 4G5/2 → 6H5/2 transition centered at 574 nm and 4G5/2 → 6H7/2 at 615 nm. Chromaticity values were calculated using CIE chromaticity diagram. The calibre of emitted light is assessed by color purity (CP) and correlated color temperature (CCT). The obtained results indicate that the synthesized BCS perovskites have excellent luminescence properties suitable for lighting technology.

Stabilization of the cubic perovskite La0.8Pr0.2BaCo2-yO6-δ by introducing Co deficiency and its effect on thermal expansion, electrical conductivity and electrochemical properties

The effects of B site deficiency on crystal structure, phase relationships, surface and high temperature properties of the cubic perovskite La0.8Pr0.2BaCo2-yO6-δ (0.00 ≤ y ≤ 0.10) have been studied. From X-ray diffraction data the single cubic perovskite phase was obtained for the Co range 0.00 ≤ y ≤ 0.05. X-ray photoelectron spectroscopy (XPS) measurements indicated the presence of Co3+ and Pr3+ and confirmed a lower Co content for the y = 0.05 sample. High temperature X-ray diffraction and dilatometry revealed the formation of secondary phases related to CoOx compounds. The introduction of Co deficiency (y = 0.02 and 0.05) at the B site prevents the formation of these secondary phases while the crystal structure remains cubic. The polarization resistance values for the oxygen reduction reaction in La0.8Pr0.2BaCo2-yO6-δ (0.00 ≤ y ≤ 0.05) electrodes were as low as 0.05 Ω cm2 at 600°C. The impedance spectra as a function of T and pO2 reveal two arcs reproduced with (R, CPE) elements. The variation of the polarization resistance (Rp) with pO2 was analyzed by using the power law. For the low frequency contribution, 0.1 ≤ ν ≤ 3 Hz, the parameter n ∼ -1, corresponds to the oxygen molecule diffusion through the porous of the electrode. For the contribution at higher frequencies, 5 ≤ ν ≤ 500 Hz, the parameter n was in the range -0.17 ≤ n ≤ -0.33, which indicates the main rate-limiting process is the oxygen exchange at the surface of the electrode. The rate of change of Rp with time for the Co-deficient electrodes, 1RpdRpdt∼6×10−4h−1, was found to be slightly slower than that obtained for the stoichiometric sample.

Investigation of structural, micro-structural, electrical, and leakage current characteristics of Bi0.5K0.5TiO3-CaSnO3-CaSeO3 ferroelectric ceramics

This research work deliberates the structural, dielectric and electrical characteristics of a mixed oxide method prepared CaSnO3/ CaSeO3 modified bismuth potassium titanate (Bi0.5K0.5TiO3 = BKT) of a chemical compositions (1-2x)(Bi0.5K0.5)TiO3-xCaSnO3-xCaSeO3 (x = 0, 0.05, 0.10, 0.15). The room temperature XRD patterns show the formation of single-phase perovskite compounds with tetragonal symmetry. Surface morphology of the pellets (carried out by using scanning electron microscopy) shows the uniform distribution of the rectangular grains with varying size over the surface. The temperature-frequency dependence of dielectric and electrical parameters has provided many interesting features of the materials including ferroelectric phase transition, dielectric relaxation/ dispersion, and conduction mechanism. The electrical properties of the parent compound BKT change significantly by equally adding CaSnO3 and CaSeO3 to it. The PE hysteresis loop confirms the ferroelectricity of the synthesized compounds. The analysis of J-E characteristics indicates that their conduction mechanism is of Ohmic type with a very small amount of leakage current.

Dielectric and ferroelectric characteristics of Ba(Ti0.25Zr0.25Hf0.25Sn0.25)O3 high-entropy ceramics

Ba(Ti0.25Zr0.25Hf0.25Sn0.25)O3 high-entropy ceramics were prepared by a standard solid state reaction process, and the dielectric and ferroelectric characteristics were investigated together with the structures. Both X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analysis demonstrated a single-phase perovskite structure in the present ceramics. A broad dielectric peak with strong frequency dispersion feature was determined, which indicated the typical relaxor nature originating from the nanoscale ferroelectric domain structures. These resulted from the structural distortion and chemical disorder due to high-entropy, where the long-range order of ferroelectric domains was destroyed. The homogeneous microstructure led to the reduced leakage current density and significantly improved dielectric strength, which was desired for the practical applications. Compared with the similar systems of Ba(Ti1-xZrx)O3 & Ba(Ti1-xSnx)O3, the present high-entropy ceramics indicated better relaxor ferroelectric characteristics.

Peculiar Properties of the La0.25Ba0.25Sr0.5Co0.8Fe0.2O3-δ Perovskite as Oxygen Reduction Electrocatalyst.

The electrochemical reduction of molecular oxygen is a fundamental process in Solid Oxide Fuel Cells and requires high efficiency cathode materials. Two La0.25Ba0.25Sr0.5Co0.8Fe0.2O3-δ-based perovskite compounds were prepared by solution combustion synthesis, and characterized for their structural, microstructural, surface, redox and electrochemical properties as potential cathodes in comparison with Ba0.5Sr0.5Co0.8Fe0.2O3-δ and La0.5Sr0.5Co0.8Fe0.2O3-δ perovskites. Results highlighted that calcination at 900 °C led to a "bi-perovskite heterostructure", where two different perovskite structures coexist, whereas at higher calcination temperatures a single-phase perovskite was formed. The results showed the effectiveness of the preparation procedures in co-doping the A-site of perovskites with barium and lanthanum as a strategy to optimize the cathode's properties. The formation of nanometric heterostructure co-doped in the A-site evidenced an improvement in oxygen vacancies' availability and in the redox properties, which promoted both processes: oxygen adsorption and oxygen ions drift, through the cathode material, to the electrolyte. A reduction in the total resistance was observed in the case of heterostructured material.

Phase Transition of High-Surface-Area Glycol-Thermal Synthesized Lanthanum Manganite.

Cubic and rhombohedral phases of lanthanum manganite were synthesized in a high-pressure reactor. A mixture of La and Mn nitrates with ethylene glycol at a synthesis temperature of 200 °C and a calcination temperature of up to 1000 °C, resulted in a single-phase perovskite, LaMnO3 validated using X-ray diffraction. Significant changes in unit cell volumes from 58 to 353 Å3 were observed associated with structural transformation from the cubic to the rhombohedral phase. This was confirmed using structure calculations and resistivity measurements. Transmission electron microscopy analyses showed small particle sizes of approximately 19, 39, 45, and 90 nm (depending on calcination temperature), no agglomeration, and good crystallinity. The particle characteristics, high purity, and high surface area (up to 33.1 m2/g) of the material owed to the inherent PAAR reactor pressure, are suitable for important technological applications, that include the synthesis of perovskite oxides. Characteristics of the synthesized LaMnO3 at different calcination temperatures are compared, and first-principles calculations suggest a geometric optimization of the cubic and rhombohedral perovskite structures.

Phase selectivity of ternary Zn-O-Sn films regulated by oxygen and fluorine

The evolvement of ternary Zn-O-Sn systems were selected through oxygen-controlled sputtering and oxygen-subtracted annealing as well as introduction of fluorine. Through XRD, Raman, PL, AFM, Transmittance, Hall-effect Testing and Resistance variation on sensing H2, the selection and formation mechanism of optional phases in the ternary Zn-O-Sn systems were clarified. During the sputtering process, oxygen addition could contribute to the selected growth of dual-phase Zn2SnO4/SnO2 with an aerobic characteristic. On the contrary, either oxygen subtraction or fluorine introduction was beneficial to the preferred growth of amorphous ZnSnO3 with an anaerobic characteristic which could further crystallize to single-phase perovskite ZnSnO3 following the vacuum annealing. Compared with dual-phase Zn2SnO4/SnO2 deposited under oxygen-containing ambience, single-phase amorphous ZnSnO3 with more oxygen vacancies presented a less light-scattered transmittance with the flattened absorption edge, a high carrier concentration ∼1017 cm−3 as well as a low carrier mobility ∼100 cm2/V·s, and a rapid response/recover rate of resistance on sensing H2.

Enhanced stability of triple-halide perovskites CsPbI3-x-yBrxCly (x and y = 0-0.024): understanding the role of Cl doping from ab initio calculations.

Doping of chloride in mixed iodide-bromide perovskites has been shown experimentally to suppress the photo-induced halide-ion segregation and enhance the stability of triple-halide perovskites (THP). However, a fundamental understanding of the effects of Cl doping is yet to be achieved especially when the doping concentration is low. Here we report the results of a state-of-the-art ab initio study of the atomic structure of THP by considering small doping concentrations of Br and Cl in CsPbI3. We find a reduction in the Pb-I bond lengths and tilting of PbI6 octahedra with Cl doping which lead to exothermic heat of mixing and therefore higher stability of THP. Moreover, using quasi-chemical approximation, our results show that there is a very small contribution of configurational entropy to Gibbs free energy at such low doping concentrations and at the operational temperature of 50 °C. This suggests that the favorable heat of mixing value is more important for the stability at low doping concentrations of Cl while a higher concentration of Cl increases the risk of halide segregation. Further calculations on Frenkel defect formation energy of I or Br-interstitial shows that the doping of Cl in I/Br mixed binary-compounds hinders the formation of Frenkel defects. These results support experiments and help to understand the role of chloride in suppressing the halide ion mobility with only a slight increase in the band gap. Accordingly, the THPs manifest a promising pathway for developing single-phase perovskites for solar cells and light-emitting diodes with improved performance and enhanced stability.

A facile mixed complex synthesis method for perovskite oxides toward electrocatalytic oxygen reduction.

The perovskite-type La(0.5+x)Sr(0.5-x)FeO3-δ (x = 0.00, 0.10, 0.20) oxides for the electrocatalytic oxygen reduction reaction (ORR) were synthesized by a facile reaction-EDTA/citric acid mixed complex sol-gel method. The cubic single-phase perovskite structure of the as-prepared oxides is demonstrated using powder X-ray diffraction (XRD). Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy/selected area electron diffraction (TEM-SAED), and X-ray photoelectron spectroscopy (XPS) characterizations were also conducted for the perovskite-type La(0.5+x)Sr(0.5-x)FeO3-δ (x = 0.00, 0.10, 0.20) oxides. Furthermore, the electrochemical ORR properties of the as-prepared oxides in alkaline media were studied, with the oxides exhibiting good electrocatalytic ORR performance.

Synthesis, structural stability and phase diagram of BiFeO3–CaSnO3 ceramics

BiFeO 3 -based materials have received extensive attention in electronic device applications due to their high Curie temperature and large electromechanical response. In this study, new solid solutions of (1- x )BiFeO 3 - x CaSnO 3 (BF-CS) ceramics were successfully synthesized via conventional solid-state reaction method. With increasing CS content, the ceramics exhibit a single-phase perovskite and the structure changes from a main rhombohedral phase with a small amount of impurity phase to a stable rhombohedral phase and then to MPB region separating the rhombohedral and orthorhombic phases in the composition of 0 ≤ x ≤ 0.15, indicating that introducing CS can stabilize the perovskite structure formed in the sintering process. Unfortunately, the solid solubility limit of CS into BF perovskite structure is reached when x > 0.15. The dielectric peak associated with oxygen vacancies become weaker and finally disappear at x = 0.15. Moreover, the ceramics with x = 0.12–0.15 feature saturated and square-shaped P - E hysteresis loops with increased polarization can be attributed to effectively promote domain switching process at MPB, in which the highest piezoelectric coefficient d 33 = 259 pC/N can be ascribed to the combined effect of coexistence phases, high relative bulk density and low leakage current. In particular, a partial phase diagram is constructed in terms of temperature and composition, which helps to understand the structure-property relations. The distinct structures and phase transition behavior on each side of the vertical MPB line offer the guidelines and strategy to design other BF-based binary or ternary solid solutions with enhanced piezoelectric property in high temperature application.

Magneto-dielectric properties of B-site doped (Fe3+, Zr4+) BiMnO3 perovskite ceramic

A Zirconium (Zr4+) and Iron (Fe3+) doped perovskite compound i.e., BiMn1-x(TE)xO3 (x = 0.0, 0.1 and TE = Fe, Zr) were successfully prepared by mechanical alloying route. The X-ray diffraction pattern and HRTEM confirms the formation of single-phase perovskite in the proposed compositions. The lattice parameters were found to be reduced with Fe3+ and increased for Zr4+ ions entering in the crystal structure by substitution of Mn3+ ion. Scanning Electron micrographs (SEM) depicted the grain refinement of the oxidex. The XPS analysis exhibited the isovalent (Fe3+) and tetravalent (Zr4+) status of doping on the B-site Their effect on the oxygen vacancies, and the reduction of Mn3+ ions are reported. The dielectric study at 100 Hz and 400 °C(max.) indicate the decrement in dielectric constant to 12.76 × 103 in Fe+3 doped ceramic and 10.68 × 103 in the case of Zr+4 doped ceramic concerning that of 13.02 × 103 in pristine ceramic. M−H loop study exhibited ferromagnetic characteristics in doped and pristine ceramics. The Ms measured as 0.135emu, 0.114emu and 0.096emu in Fe doped, Zr doped and pristine ceramics respectively. The coexistence of magnetic and dielectricity exhibited the justified modifications of manganates perovskite ceramics and competently met the challenge of replacing conventional materials.

Development of oxide composite materials for cathode element of IT-SOFCs

Investigating the properties of composite oxide for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been done as a new cathode material. Using a solid-state reaction method, the metallic oxide material has been employed to create the composite model system. During the sintering process, a model system of Sm0.5Sr0.35Ba0.15FeO3-δ (SSBF15) was constructed. Thermal gravimetric analysis (TG) was played to utilize the oxygen content and weight loss of the model. In the meantime, the structure of the composite was characterized using X-ray diffraction (XRD), and the conductivity properties were tested by thermal conductivity. The structural design was made possible by the findings, which revealed that the composite model structure exhibited the crystalline structure with perovskite phase. Weight losses during the construction of the structure were reflected in the decomposition and evaporation of the composite's constituent parts. After the calcination process up to 950 °C, the model system's formation oxygen content was obtained of 2.94 in 800 °C. The electrical conductivity maximum obtained in 12.2 S·cm-1 at 430 °C. At low temperatures, the conductive behavior was affected by the metallic element, while at higher temperatures, it was influenced by the ionic structure. As a result, mixed ionic and electric conductors (MIEC) were extensively utilized in the process of generating the conductive properties. The SSBF15 composite has a good chance of being used as an alternative cathode material with a perovskite single phase for future IT-SOFCs applications based on the structure and conductivity results. Additional testing and observation are required to determine the resistance's value when incorporated into the electrolyte and its heat expansion properties

Giant baroresistance effect in lanthanum-strontium manganite nanopowder compacts

Nowadays, there is an urgent issue in creating highly sensitive current, magnetic field, temperature, and pressure sensors. For this purpose, a magnetic La0.6Sr0.3Mn1.1O3 (LSMO) nanopowder has been synthesized by atomization hydrolysis and compacted under different pressures up to 1600 MPa. Their phase composition, crystal structure, morphology, magnetic, magneto-resonance, transport, magnetoresistance (MR), and baroresistance (BR) properties have been comprehensively studied. It has been shown that the LSMO nanopowder is a single-phase perovskite and consists of spherical-like particles with an average size of 37 nm. As the pressure increases to 1600 MPa, the filling factor in the compacts increases, decreasing the average distance between particles. In the room temperature range, the LSMO nanopowder is in a ferromagnetic state with a Curie temperature TC = 367 K and does not depend on the compacting pressure P. The conductivity is thermally activated by hopping conduction along the nearest particles. With increasing P, a monotonic decrease in resistivity is due to reducing the distance between particles. The temperature dependences of the MR have a tunneling character. Giant BR effect with the establishment of the following important applied properties has been found: (i) the BR effect is not limited by the Curie temperature and is observed both in the ferromagnetic and paramagnetic states; (ii) the BR effect under constant pressure slightly depends on the temperature in a wide range from – 193 to + 127 ℃; (iii) in the pressure range from 0 to 400 MPa, the BR effect has the highest sensitivity of 0.1%/MPa. The obtained results and established regularities in the LSMO nanopowder compacts can be used to create pressure sensors for modern intelligent process control systems.