Manganite Ceramics Research Articles

The modifications in structural, optical, and electro-magnetic phase transition of Vanadium-doped La-based manganite ceramics La0.7Pb0.3Mn1−yVyO3 (y = 0 – 0.1)

The present paper is centred around the investigation of the structural, electrical, and magnetic properties displayed by the novel perovskite polycrystalline La0.7Pb0.3Mn1−yVyO3 (y = 0 – 0.1) prepared via the conventional solid-state technique. The structural properties of the samples were assessed through the utilisation of X-ray diffraction (XRD) analysis. Subsequently, the obtained diffraction data underwent refinement employing Rietveld refinement techniques in order to determine the structural parameters of the samples a, b, c, V and Mn–O bond length and angle. The study of X-ray diffraction (XRD) peaks reveals that all the samples exhibited crystallization in a single phase, devoid of any impurities. All of the samples exist in rhombohedral orientation with a space group of R-3c. The tolerance factor of the samples was calculated in order to assess the severity of lattice distortion, decrease from 0.872 (y = 0) to 0.831 (y = 0.1). The microstructural characteristics of the samples were analysed using a field-emission scanning electron microscope (FESEM). The morphology results reveal that a rise in the amount of V leads stimulates the grain growth in the sample, as evidenced by the increase in grain size from 2.17 µm (y = 0) to 3.71 µm (y = 0.1). The Fourier transform infrared (FTIR) analysis revealed an absorption range of 500 – 600 cm-1, which is indicative of the Mn–O bond deformation vibration. This observation suggests the presence of a MnO6 bond in the sample. The Tauc plots derived from the UV-Vis spectroscopy data reveal a notable increase in the optical bandgap (Eopt) as the concentration of V increases. Specifically, the Eopt values rise from 1.71 eV (y = 0) to 2.30 eV (y = 0.1), falling within the range typically observed for semiconductor materials. A distinct metal-insulator transition was observed in all of the samples, exhibiting a range of TMI values ranging from 250 K to 292 K. The scattering model was employed to determine the itinerant eg behaviour in the low temperature region, whilst the SPH model was used to explore the conduction behaviour in the high temperature region. The magnetic characteristic of the samples was investigated using the Alternating Current Susceptibility (ACS) and Vibrating Sample Magnetometer (VSM) techniques, which confirms the existence of a shift in phase from ferromagnetic (FM) to paramagnetic (PM). The TC value exhibits a declining trend from 298.8 K (y = 0) to 274.8 K (y = 0.1).

Modeling of the magnetobarocaloric effect in the framework of the mean-field theory

The magnetobarocaloric effect (MBCE) is studied, which consists in the change of entropy and temperature in a layer of magnetostrictive material upon simultaneous application of a magnetic field and pressure. The MBCE is described in the framework of the generalized mean-field model accounting both the nonlinear dependence of the effective magnetic intensity on magnetization and its dependence on pressure. To test the developed MBCE model, a comparison with experimental data for La0.85Ag0.15MnO3 manganite ceramics is performed. Using a single set of model parameters, the results can be reproduced with good accuracy. Based on the obtained values for the material constants, the thermodynamic efficiency of the Brayton cycle on the magnetobarocaloric effect is calculated. The combined use of magnetic field and pressure allows to significantly increase the efficiency of this cycle (by 10%–20%), while the entropy can increase by 45%.

Retraction Note to: Structural, dielectric, and electrical properties of cerium-modified strontium manganite ceramics

Retraction Note to: Structural, dielectric, and electrical properties of cerium-modified strontium manganite ceramics

Enhanced electrical transport properties of polycrystalline La0.67Sr Ca0.23-K0.1MnO3 ceramics through A-site multielement co-doping

Current research on perovskite materials is mainly focused on how to achieve a high temperature coefficient of resistivity (TCR) in anticipation of application in infrared detection. In this study, we report the superior electrical transport properties of polycrystalline La0.67SrxCa0.23-xK0.1MnO3 (LSCKMO) (0.03 ≤ x ≤ 0.13) ceramics produced through the sol-gel process using different Sr doping contents. Based on previous studies, polycrystalline manganite ceramics with a higher TCR at room temperature were obtained by optimising the composition ratio of Sr or Ca. In the process of continuous doping, the crystal structure of the polycrystalline LSCKMO ceramics changed significantly from Pnma to R 3‾ c. The final polycrystalline La0.67Sr0.10Ca0.13K0.1MnO3 ceramic material was obtained with a TCR of 17.16% K-1 and peak TCR temperature of 289.42 K, demonstrating that suitable candidates can be obtained for infrared detection technology.

Doping nanoarchitectonics through exchange of Ag+ with Na+ in La0.7Ca0.1Sr0.1X0.1MnO3 (X = Ag+ or Na+) manganite ceramics for enhancement and levelling tendency of magneto resistivity

Doping nanoarchitectonics through exchange of Ag+ with Na+ in La0.7Ca0.1Sr0.1X0.1MnO3 (X = Ag+ or Na+) manganite ceramics for enhancement and levelling tendency of magneto resistivity

Correction: Structural, dielectric, and electrical properties of cerium-modified strontium manganite ceramics

Correction: Structural, dielectric, and electrical properties of cerium-modified strontium manganite ceramics

Improvement of electrical and magnetic properties in La0.67Ca0.33Mn0.97Co0.03O3 ceramic by Ag doping

For the perovskite manganite La1-xCaxMnO3, achieving high temperature coefficient of resistance (TCR) and magnetoresistance (MR) is the key to realize its potential applications. In this study, high-quality La0.67Ca0.33Mn0.97Co0.03O3:Agx polycrystalline ceramics were prepared by the sol-gel method. The results show that Ag doping has important impact on metal-insulator and ferromagnetic-paramagnetic transitions. A Ag doping amount increases, the grain size of the samples increases at x = 0.05 and then decreases. The doping of Ag can improve the crystalline quality of the samples and enhance the connectivity between grains, thereby improving the metallicity of the system. Additionally, with Ag doping amount increases, the resistivity of the samples gradually decreased, while the Curie temperature and the metal-insulator transition temperature gradually increased. Especially after Ag doping, both the TCR peak (TCRpeak) and the MR peak (MRpeak) values are significantly improved. The TCRpeak reaches 65.2%·K−1 at x = 0.1, while the MRpeak is as high as 82.6% at x = 0.05 under 1 T magnetic field. Doping perovskite manganite ceramics with Co and Ag can greatly optimize their TCR and MR, favoring the potential applications of these materials.

RETRACTED ARTICLE: Structural, dielectric, and electrical properties of cerium-modified strontium manganite ceramics

RETRACTED ARTICLE: Structural, dielectric, and electrical properties of cerium-modified strontium manganite ceramics

Enhancing magnetoresistive features of iron-substituted La0·8Sr0·2MnO3 ceramic manganites

The influence of iron content on the structural, microstructural, magnetic, and electrical-transport features of the ceramic perovskite manganites of the form La0·8Sr0·2Mn1-xFexO3 (x=0.0, 0.05, 0.1, and 0.2) was investigated. A single phase of rhombohedral-distorted structure with an R 3‾ c space group was confirmed for all synthesized ceramic samples. The microstructures of the manganite ceramics were improved by iron substitution. The magnetic and electrical-transport studies show that samples with x=0.0, 0.05, and 0.1 display phase transitions from ferromagnetic to paramagnetic state and metallic to insulating one with increasing temperature. The phase transition temperatures, i.e., Curie temperature, TC, and the resistance transition temperature TMI, are found to be lowered with the increase in the Fe concentration. The temperature coefficient of resistance (TCR) value for the x=0.0 sample is obtained ∼2.16% K−1 and slightly decreased to ∼1.55% K−1 with a 5% Fe substituted sample. As x rise to 0.1, we obtain the maximum TCR value of ∼8.23% K−1. At the same time, the maximum magnetoresistance is obtained as 48.1% at 233 K for the x=0.1 sample. One of the most important findings in this paper is that Fe substitution is very useful for improving magneto-electrical features of the La0·8Sr0·2MnO3 ceramics. Moreover, to better understand the temperature dependence of the electrical resistivity data, the experimental findings were fitted to the equations of several models.

Intercluster interaction and critical behavior near magnetic phase transition of electron-doped ceramic manganite Ca0.85Nd0.15MnO3

Intercluster interaction and critical behavior near magnetic phase transition of electron-doped ceramic manganite Ca0.85Nd0.15MnO3

Effect of perovskite template seeds on microstructures and thermoelectric properties of Ca0.87Ag0.1Dy0.03MnO3 ceramics

Calcium manganite (CaMnO3) ceramics, members of the perovskite family, have attracted considerable attention in the field of thermoelectric materials owing to their environmental friendliness, chemical stability, long lifetime, and low cost. Ruddlesden–Popper Ca3Mn2O7 and plate-like perovskite CaMnO3 templates were synthesized using the molten salt method. Perovskite CaMnO3 template seeds with a radius-thickness ratio of 16.8 were obtained via topochemical conversion process, demonstrating an obviously anisotropy. The template seeds were introduced into Ca0·87Ag0.1Dy0.03MnO3 ceramics to promote the grain growth. The bulk density of the sample containing 20 wt% template seeds was 96.0%. An electrical resistivity of 5.35 mΩ cm, a Seebeck coefficient of − 196 μV/K, and a power factor of 0.73 mW/m·K2 were obtained. Such enhancements in thermoelectric properties could be attributed to the formation of grain boundaries between stripe-like and equiaxial grains. Additionally, the maximum ZT value of 0.35 reached at 500 °C, which is 57% higher than that of the sample without template seeds. Therefore, it is believed that this study can lay the foundation for textured CaMnO3 ceramics with superior thermoelectric properties.

Enhancement and Levelling Tendency of Magneto Resistivity by Doping Exchange of Ag+ with Na+ in La0.7ca0.1sr0.1x0.1mno3 (X = Ag+ or Na+) Manganite Ceramics

Enhancement and Levelling Tendency of Magneto Resistivity by Doping Exchange of Ag+ with Na+ in La0.7ca0.1sr0.1x0.1mno3 (X = Ag+ or Na+) Manganite Ceramics

Improvement in the Magnetoresistive Properties and Temperature Coefficient of Resistance in Ceramic Manganites with Iron Substitution

Improvement in the Magnetoresistive Properties and Temperature Coefficient of Resistance in Ceramic Manganites with Iron Substitution

Improvement in the Magnetoresistive Properties and Temperature Coefficient of Resistance in Ceramic Manganites with Iron Substitution

Improvement in the Magnetoresistive Properties and Temperature Coefficient of Resistance in Ceramic Manganites with Iron Substitution

Expansion of Multifunctionality of Non-Stoichiometric Manganite Ceramics Owing to Post-Annealing: Effect of High Pressure and Electrochemical Studies

Expansion of Multifunctionality of Non-Stoichiometric Manganite Ceramics Owing to Post-Annealing: Effect of High Pressure and Electrochemical Studies

Retraction Note to: Structural, dielectric and electrical properties of cerium-modified strontium manganite ceramics

Retraction Note to: Structural, dielectric and electrical properties of cerium-modified strontium manganite ceramics

The effect of Eu dopant on the structural, dielectric and impedance properties of PrMnO3 manganite ceramics

In this paper, we reported the results of structural and electrical properties of Pr1–xEuxMnO3 (PEMO; x = 0.10, 0.30 and 0.50) manganites, synthesized by conventional solid-state reaction method. Structural studies revealed a mixed-phase nature (with some impurity phase) in all PEMO samples, having a rhombohedral and orthorhombic structure. The unit cell volume decreased slightly with Eu content in PEMO ceramics. The dielectric and impedance measurements were conducted in the temperature range of 25–450 °C and frequency range of 50 Hz to 4 MHz. The low values of activation energy (0.278, 0.138 and 0.017 eV for x = 0.10, 0.30 and 0.50, respectively) showed the presence of oxygen vacancies. Cole–Cole plot demonstrated that the grain boundary effect diminished with increasing temperature. This was due to the development of oxygen vacancies during sintering at higher temperatures. These defects influenced the impedance at the barrier of the grain and grain boundary interface.

TCR and MR room-temperature enhancing mechanism of La0.7K0.3−xSrxMnO3 ceramics for uncooling infrared bolometers and magnetic sensor devices

During the last decades, significant improvements of both the magnetoresistance (MR) and the temperature coefficient of resistivity (TCR) of ceramics (at room temperature) have opened new opportunities to build uncooled infrared bolometers and magnetic sensor devices. Herein, polycrystalline La0.7K0.3−xSrxMnO3 ceramics, with 0.00 ≤ x ≤ 0.25 were prepared by a facile sol–gel method. TCRmax increased from 6.4% K−1 at 270.2 K (for x = 0.00) to 11.9% K−1 at 291.2 K (for x = 0.05), and the low-field (1 T) MRmax reached 30.5% at 294.5 K. The phenomenological percolation (PP) model, the Jahn–Teller (JT) effect, and the double exchange (DE) mechanism were used for the comprehensive understanding of the nature of electromagnetic transport properties. Another interesting finding is that the TCR characteristic can be calculated by using the PP model. The JT effect, DE mechanism, and PP model clearly modified both the TCR and MR of the prepared ceramics. The relationship between the proposed TCR/MR dependency and several scattering factors opens up new avenues to enhance TCRmax and MRmax of manganite ceramics.

RETRACTED ARTICLE: Structural, dielectric and electrical properties of cerium-modified strontium manganite ceramics

In this communication, structural, dielectric, spectroscopic and electrical characteristics of cerium-modified strontium manganite perovskite of a composition SrMn0.9Ce0.1O3, (SMCO) prepared by a high-temperature solid-state reaction technique have been reported. The preliminary structural analysis of SrMnO3 exhibits hexagonal (P63/mmc) crystal structure, whereas SMCO, synthesized under identical conditions, shows a tetragonal (I4/mmm) structure. The average crystallite size and lattice strain of SMCO using X-ray data were found to be 74 nm and 0.107%, respectively. The surface morphology, study by the scanning electron microscopy (SEM), shows distinct grains of average size of 19.2 μm. The X-ray photoelectron spectroscopy (XPS) study confirms the oxidation state of Mn and Ce as Mn4+ and Ce4+ and composition of SMCO compound. The grains and the grain boundaries play an important role to explain the conduction mechanism. The bulk resistance (Rb) decreases from 1.020 × 105 Ω at 25 °C to 1.096 × 103 Ω at 500 °C. This behaviour of decrease in resistance with the increase in temperature shows semiconductor (negative temperature coefficient resistance) nature of the material at high temperatures. The variation of the activation energies with temperature suggests that the ac conductivity is thermally activated. The immobile charge carriers at low temperatures and defects and oxygen vacancies at high temperatures are responsible for the thermally activated conduction mechanism. Detailed studies of electrical parameters as a function of frequency at different temperatures using dielectric and impedance spectroscopy of SMCO have provided conduction mechanism and structural properties relationship.

Processing and properties of ceramic yttrium manganite sintered by different methods

Intergranular and intragranular cracks that usually form during sintering of yttrium manganite (YMnO3) ceramic samples hinder the densification process of this ceramic and deteriorate its magnetic and ferroelectric properties. To overcome this problem, mechanochemically synthesized YMnO3 powder was sintered using two different processes: Conventional Sintering (CS) and Pulsed Electric Current Sintering (PECS). All samples were characterized by XRD, SEM and FESEM and their magnetic and ferroelectric properties were investigated. Apart from their phase composition, conventionally sintered ceramic samples showed cracks throughout their whole volume, reaching a maximum relative density of 85 %. However, it was found that PECS process could significantly reduce the presence of cracks within samples whose relative density reached 99.8 %.