Electrical Properties Of La0 Research Articles

Microstructural and electrical properties of La0.9B0.1AlO3 (B=Pr, Nd, Sm) ceramics obtained by rare-earth ion doping

This study used the solid-phase method to prepare thermosensitive perovskite ceramics, La0.9B0.1AlO3 (B = Pr, Nd, Sm). The XRD and EDS results indicated that all components presented a single phase and all elements were uniformly distributed, formed a good solid solution. The SEM results clearly illustrated that the doped elements had enhanced the surface morphology, resulting in more uniform grain formation. The TEM results showed that linear defects were present, which led to an uneven stress distribution; consequently, this enhanced the carrier transport. The alternating current (AC) impedance showed that the grain boundary resistance determined the overall complex impedance and exhibited a different conductive mechanism with increasing temperature, from polariton to ion conduction. With the introduction of Nd3+, the conductivity of La0.9Nd0.1AlO3 increased and its temperature range increased from 600 – 1400 °C to 100–1500 °C. In La0.9Sm0.1AlO3, the presence of Sm2+ enhances the aging stability by elevating the oxygen vacancy concentration and the aging drift rate (ΔR/R0) was found to be lower than 2 %. In addition, DFT-based calculations were performed to investigate the property changes in the crystal structure and energy band structure of pure and doped LaAlO3. This study demonstrated an effective way to improve the performance of high-temperature thermistor materials using different doping strategies.

Effects of Al3+ doping on the structure and electrical properties of La0.9Sr0.1CrO3 ceramics

Perovskite lanthanum chromate (LaCrO3) has been widely investigated for applications as functional material, its properties can be finely tuned through doping. This study explores the effect of Al3+ doping on the structure and electrical properties of La0.9Sr0.1Cr1-xAlxO3 ceramics. Our findings reveal that Al3+ doping significantly influences the consistency of grain size and electrical transport properties of these ceramics. As x increases, the grain size decreases and obtains its minimum at x = 0.5. Compared to the undoped La0.9Sr0.1CrO3, Al3+ doping significantly reduces the resistivity. For x = 0.3, the resistivity obtains its minimum 142.60 Ω cm at −75 °C, while the B-value is reduced to 405 K. These results demonstrate the potential of Al3+ doping in enhancing the thermal sensing properties of LaCrO3 ceramics and understanding of semiconductor behavior for electron device applications.

Investigation of the structural, magnetic, and electrical characteristics of the La0.7Sr0.25Na0.05Mn0.8Ti0.2O3.

This article reveals the crucial structural, magnetic, and electrical properties of La0.7Sr0.25Na0.05Mn0.8Ti0.2O3 (LSNMTO) manganite, highlighting the significance of this material in the field of materials science. Gain a deeper understanding of the promising properties of LSNMTO and its potential for technological advancement by delving into this informative article. The X-ray diffraction data of the LSNMTO indicate that this ceramic solid solution crystallizes in the R3̄c rhombohedral structure. The magnetic results confidently demonstrate that the LSNMTO ceramic undergoes a transition from paramagnetic to ferromagnetic phases around 125 K. This significant finding could pave the way for further progress in the field of materials science. The DC conductivity response confirms the semiconductor nature of the elaborated compound over the studied temperature domain. Such behavior is linked to the contribution of the small polaron hopping mechanism at elevated temperatures and the Shklovskii Efros variable range hopping process at low temperatures. In the limit of the AC regime, the temperature-dependent AC conductivity confirms the appearance of a metal-semiconductor behavior at T M-S = 120 K that confirms the strong correlations between the transport and the magnetic properties of the sample. Over the explored temperature domain, the conductivity spectra follow a power law-like behavior. The scaled conductivity curve of LSNMTO is not superimposed on the particle grains' restricted reaction area. The Summerfield scaling of the electrical conductivity confirms with confidence the significant contribution of carrier concentration to the overall conduction of the material.

Influence of component manipulation on the structural, mechanical, thermophysical and electrical properties of La0·2Ce0.2Nd0.2(ZrxY1−x)0.4O2−δ high-entropy ceramics

A series of high-entropy ceramics (HECs) with compositions of La0·2Ce0.2Nd0.2(ZrxY1−x)0.4O2−δ (x = 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0, the corresponding names being HEC(Zr0·5/Y0.5, Zr0·6/Y0.4, Zr0·7/Y0.3, Zr0·8/Y0.2, Zr0·9/Y0.1, Zr1·0/Y0)) were sintered in air at 1600 °C for 10 h. When x is in the range of 0.5–0.7, a fluorite phase is formed. Then, as x exceeds 0.7, a second pyrochlore-structured phase appears, and its content gradually increases with the increasing x. The grain growth of the samples is inhibited by increasing in the relative Zr content. The grain refinement and the formation of second phase reduce the thermal conductivity and reinforce the mechanical properties of the samples. HEC(Zr0.9/Y0.1) has the lowest thermal conductivity (50–500 °C) and brittleness index, as well as the highest fracture toughness among all samples. In addition, La0·2Ce0.2Nd0.2(ZrxY1−x)0.4O2−δ ceramics have excellent thermal stability under Ar atmosphere in 50–1400 °C. The thermal expansion coefficients of the samples marginally change regardless of the variation in x. All samples show higher oxygen barrier property than Y2O3-stabilized ZrO2.

Effect of TiO2 addition on the structural and electrical properties of La0.67Ca0.33MnO3

Numerous studies have been conducted on perovskite manganites to enhance the low field magnetoresistance (LFMR). One effective approach is adding an insulating oxide as the artificial boundary layer outside the manganite grain. This research aims to determine the structural and electrical properties of La0.67Ca0.33MnO3 (LCMO) when added with different contents of TiO2. LCMO powder was prepared via sol–gel route before appended with TiO2 nanoparticle to form (1 − x) LCMO: x TiO2, x = 0.00, 0.005, 0.010, 0.030 and 0.050. The structural analysis by X-ray diffraction (XRD) revealed no significant changes in the lattice parameter, crystallite size, bond length and angle as the concentration of TiO2 increased. The TiO2 in LCMO caused an increase in resistivity and a decrease in metal–insulator transition (TMI). This indicates the double exchange (DE) has been suppressed by the TiO2 addition, which acts as disordered layers at LCMO grains surface. The electrical resistivity of the samples was fitted with theoretical models, and the conduction mechanism is explained by the grain/domain boundary effect and the small polaron hopping (SPH) model. The first fitting inferred that the grain/ domain boundary effect plays an inevitable role throughout the conduction in the metallic region. The latter supports the notion that the presence of TiO2 in the LCMO compound produces a more resistive grain boundary.

Effect of Sintering Temperature and Polarization on the Dielectric and Electrical Properties of La0.9Sr0.1MnO3 Manganite in Alternating Current

The electrical characterization ofa La0.9Sr0.1MnO3 compound sintered at 800, 1000 and 1200 °C was investigated by means of the impedance-spectroscopy technique. As the results, the experimental conductivity spectra were explained in terms of the power law. The AC-conductivity study reveals the contributions of different conduction mechanisms. Indeed, the variation in the frequency exponents (‘s1’ and ‘s2’) as a function of the temperature confirms the thermal activation of the conduction process in the system. It proves, equally, that the transport properties are governed by the non-small-polaron-tunneling and the correlated-barrier-hopping mechanisms. Moreover, the values of the frequency exponents increase under the sintering-temperature (TS) effect. Such an evolution may be explained energetically. The jump relaxation model was used to explain the electrical conductivity in the dispersive region, as well as the frequency-exponent values by ionic conductivity. Under electrical polarization with applied DC biases of Vp = 0.1 and 2 V at room temperature, the results show the significant enhancement of the electrical conductivity. In addition, the dielectric study reveals the evident presence of dielectric relaxation. Under the sintering-temperature effect, the dielectric constant increases enormously. Indeed, the temperature dependence of the dielectric constant is well fitted by the modified Curie–Weiss law. Thus, the deduced values of the parameter (γ) confirm the relaxor character and prove the diffuse phase transition of our material. Of note is the high dielectric-permittivity magnitude, which indicates that the material is promising for microelectronic devices.

Effect of Ag doping on structure and electrical properties of La0.7Ca0.26K0.04MnO3 ceramics

Effect of Ag doping on structure and electrical properties of La0.7Ca0.26K0.04MnO3 ceramics

Impact of Sintering Temperature on the Electrical Properties of La0.9Sr0.1MnO3 Manganite

La0.9Sr0.1MnO3 nanoparticles were prepared using the citrate–gel route and sintered at different temperatures (TS = 600 °C, 800 °C, and 1000 °C). The x-day diffraction patterns reveal that the samples exhibit a single phase with a rhombohedral (R3¯C) structure. The transmission electron microscopy technique shows an increase in the grain size when the sintering temperature (TS) rises. The obtained values are approximately similar to that of crystallite size calculated from x-ray diffraction patterns. The impact of sintering temperature (TS) on the electrical properties of La0.9Sr0.1MnO3manganite is examined using the impedance spectroscopy technique. A metal-semi-conductor transition at a specific temperature (TM-SC) is observed for all samples. Indeed, the sintering temperature increase induces the shift of this transition temperature toward higher temperatures. Such a behavior is explained by the increase in the grain size. An agreement between the metal-semi-conductor transition values coming from the DC resistivity and the grain boundaries analyses is observed. This agreement proves the contribution of the grain boundaries in the electrical properties of the studied samples. In addition, the presence of the relaxation phenomenon is confirmed. The fitted Nyquist plots show the correlation between the microstructure of the material and the electrical properties using an electrical equivalent circuit model. The DC resistivity and the impedance analyses reveal the thermal activation of the transport properties in the investigated system.

Effect of deposition time on electrical properties of La0.67Ca0.33MnO3:Ag0.2 thin films by pulsed laser deposition

Effect of deposition time on electrical properties of La0.67Ca0.33MnO3:Ag0.2 thin films by pulsed laser deposition

Optical properties of La1−xSrxVO3 (0 ≤ x ≤ 1) films grown on LSAT substrates using radio frequency sputtering deposition

La1−xSrxVO3 (0 ≤ x ≤ 1) films can be transparent conducting oxides such as n-type SrVO3 and p-type La2/3Sr1/3VO3 films. They also show a semiconductor-to-metal transition (SMT) near x = 0.2. The optical and electrical properties of La1−xSrxVO3 (0 ≤ x ≤ 1) films grown on (LaAlO3)0.3(Sr2AlTaO6)0.7 (LSAT) substrates using RF sputtering deposition were investigated. Resistivities of La1−xSrxVO3 showed SMT near x = 0.2. La1−xSrxVO3 films grown on LSAT substrates were found to have high crystallinity using θ−2θ scan and grazing incidence x-ray diffraction measurements. Dielectric functions of La1−xSrxVO3 films were measured using spectroscopic ellipsometry. The evolution of optical spectra of La1−xSrxVO3 films from LaVO3 to SrVO3 was compared to the electronic band structures as a function of Sr composition, which was either experimentally observed or theoretically calculated in the literature. With increasing Sr composition, the interband transition energies of O 2p to V 3d states near 4 eV changed linearly as a function of Sr content.

Electrical properties of La0.72Ca0.28MnO3: Ag0.2 thin films of different deposition time prepared by deposited pulsed laser method

Electrical properties of La0.72Ca0.28MnO3: Ag0.2 thin films of different deposition time prepared by deposited pulsed laser method

Impedance spectroscopy and conduction mechanism in La0.8Pb0.2Fe0.75Mg0.25O3 perovskite

In this research work, the structural and electrical properties of La0.8Pb0.2Fe0.75Mg0.25O3, elaborated by sol–gel process, are studied. The X-ray diffraction profile refinement shows that the structure of this perovskite is orthorhombic. DC conductivity (σDC) reveals the semi-conductor behavior and the activation energy is estimated to be 547 meV. It is also obvious that the conductivity AC follows Jonsher's universal power-law and the exponent “s” decreases with temperature increase, showing that the phenomena of conduction is related to Correlated Barrier Hopping (CBH). The plots of Nyquist demonstrate the existence of two different relaxation contributions linked to grain boundaries and grains.

Electronic phase derived impedance spectroscopic behavior of La0.5Nd0.2A0.3MnO3 manganites

In the present communication, structural, microstructural and electrical properties of La0.5Nd0.2Ca0.3MnO3 (LNCMO) and La0.5Nd0.2Sr0.3MnO3 (LNSMO) mixed valent manganite films, grown on single crystalline (0001) Al2O3 (ALO) substrates using pulsed laser deposition (PLD) technique, have been studied. After deposition, one set of LNCMO and LNSMO films were annealed in oxygen environment at 500 °C (hereafter referred as LNC–A & LNS–A, respectively) and compared their properties with other set of PLD as–grown LNCMO and LNSMO films (hereafter referred as LNC and LNS, respectively). Single crystalline growth of LNCMO films and polycrystalline growth of LNSMO films have been identified through X–ray diffraction (XRD) measurement. Atomic force microscopy (AFM) measurement for morphological studies indicates that divalent dopant and oxygen annealing process play an important role in governing the grain growth and surface nature of the studied films. A decrease in the value of resistance (R) and impedance (Z) with increase in frequency under the applied magnetic field (H = 1 T) has been observed for all the studied films. For LNC & LNC–A films, reactance is found to decrease monotonically with increase in frequency throughout its range studied while for LNS and LNS–A films, reactance initially increases followed by reduction in its value with increase in frequency under 0 and 1 T magnetic field has been observed. The variation in MR for LNS and LNS–A films has been discussed in the context of charge transport mechanism and Lorentz force. Further, to discuss the role of grain and grain boundaries, nyquist plots and their suitable fits under zero and 1 T external magnetic field have been investigated for all the studied mixed valent manganite films. Important role of phase separation scenario in studied manganite films has been discussed in detail based on magnetization measurement. Double magnetic phase transition and fluctuations in derivative of magnetization have been ascribed to the phase separation scenario of LNCMO / ALO and LNSMO / ALO mixed valent manganite thin films.

Structural and Electrical Properties of La<sub>0.7</sub>Ca<sub>0.3</sub>MnO<sub>3</sub> /α-Fe<sub>2</sub>O<sub>3</sub> Composites

Colossal magnetoresistive (CMR) materials have huge potential in modern application and it has been widely used in magnetic sensing industry. From the literature, an incorporation of secondary insulating phase into mixed-valence manganites could improve its extrinsic effect especially low-field magnetoresistance (LFMR). However, nanoparticle addition could lead to substitution and diffusion with its parent compound. In this work, the structural and electrical properties of La0.7Ca0.3MnO3 (LCMO) were investigated by adding the α-Fe2O3 nanoparticle with ratio of 0.00, 0.05, 0.10, 0.15 and 0.20 as the artificial grain boundaries. The LCMO compound has been synthesised using sol-gel route. The samples were chosen to sinter at 800°C to obtain the pure LCMO phase by referring to the thermogravimetric analysis (TGA). The structural properties were investigated by an X-ray diffractometer (XRD) while electrical properties were measured by a four-point probe (4PP) system. XRD patterns showed the coexistence of two phases (LCMO & α-Fe2O3). LCMO crystallised in orthorhombic structure with space group Pnma while α-Fe2O3 exhibited in hexagonal form with space group R-3c. As the content of α-Fe2O3 increases, the resistivity of the samples increases drastically. Nevertheless, the addition of iron oxide has no significant effect on the metal-insulator transition temperature (T­MI). From the XRD and 4PP analysis, it can be deduced that the α-Fe2O3 nanoparticles do not react with LCMO compound and successfully formed the La0.7Ca0.3MnO3 /α-Fe2O3 composites. The resistivity increases when the nano-sized α-Fe2O3 is added into LCMO nanocomposites due to the insulator nature of α-Fe2O3.

Effect of Fe and Co doping on structural and electrical properties of La0.5Sr1.5MnO4 layered-structure and the corresponding La0.5Sr0.5MnO3 perovskite

In this study, structural and electrical properties of La0.5Sr1.5Mn0.5T0.5O4 (T = Mn, Fe, and Co) manganites, with K2NiF4 structure, have been investigated and compared with those of La0.5Sr0.5Mn0.5T0.5O3 perovskite manganites. The room temperature X-ray diffraction patterns of the synthesized La0.5Sr1.5Mn0.5T0.5O4 layered-structures and La0.5Sr0.5Mn0.5T0.5O3 perovskites were indexed with tetragonal and orthorhombic structures, respectively. The FE-SEM images revealed that the average size of La0.5Sr1.5Mn0.5T0.5O4 particles prepared by solid state reaction method using La0.5Sr0.5Mn0.5T0.5O3, as the starting materials, is larger compared with that of La0.5Sr0.5Mn0.5T0.5O3 synthesized by the modified sol-gel route. The SEM micrographs of the sintered ceramics indicated that the average grain size of La0.5Sr1.5Mn0.5T0.5O4 layered-structures is larger than that of the corresponding La0.5Sr0.5Mn0.5T0.5O3 perovskites, which is supported by FE-SEM images. The electrical conductivity measurements, in the range of room temperature to 800 °C, indicated that these oxides have semiconducting behavior, and their transport properties can be described by small polaron conduction mechanism. Results showed that La0.5Sr1.5Mn0.5T0.5O4 layered-structures have lower electrical conductivity in comparing to the corresponding La0.5Sr0.5Mn0.5T0.5O3 perovskites, since the perovskite structure provides three-dimensional (Mn/T)3+–O–(Mn/T)4+ interaction, whereas it is two-dimensional interaction in the layered-structure. The reduction in conductivity with Fe doping could be due to the presence of Fe3+ ions, which causes a decrease in Mn3+/Mn4+ ratio and the number of electrons involved in hopping mechanism. The electrical conductivity enhancement of La0.5Sr1.5MnO4 by doping Co can be associated with reducing Mn/Co‒O bond length and the increase in the overlap between O 2p and Mn/Co 3d orbitals.

Investigation of the conduction mechanism, high dielectric constant, and non-Debye-type relaxor in La0.67Ba0.25Ca0.08MnO3 manganite

The conduction mechanism and electric properties of La0.67Ba0.25Ca0.08MnO3 (LBCM) were analyzed depending on temperature and frequency. The frequency dependence of electrical conduction plot was explained by the jump relaxation model. The electrical conduction process was based on both theoretical conduction models assigned to the Correlated Barrier Hopping and Non-overlapping Small Polaron Tunneling mechanism. The impedance plot studies reveal that the relaxation is a non-Debye poly-dispersive pattern in the LBCM. This compound has excellent dielectric properties such as the dielectric permittivity exceeding 105 at room temperature, i.e., colossal permittivity, and is one of the highest values recorded for ceramic capacitors. Thus, evolution of dielectric permittivity, described in terms of spatial charge polarization based on Koop's phenomenological theory and Maxwell–Wagner's (M– W) model and high dielectric response, has been driven by barrier layers into the grain boundaries and blended structures of Mn3+/Mn4+. The relaxation processes were examined with modulus, impedance formalism, and electrical conductivity. In the thermal analysis, the relaxations mechanism are related oxygen vacancies.

Correlation between magnetic and electrical properties of La0.7Ba0.15Ag0.15MnO3 manganite prepared by sol gel method

We have reported the solgel synthesis, the structural analysis, and the correlation between magnetic and electrical properties of La0.7Ba0.15Ag0.15MnO3 manganite. The phase purity and structure of this sample were checked by X-ray diffraction technique and Rietveld analysis. M(T) measurement shows a ferromagnetic (FM)-to-paramagnetic (PM) phase transition of second-order type at Curie temperature TC = 255 K. The obtained magnetocaloric parameters offer to the sample the possible use in the magnetic refrigeration technology. The resistivity data, ρ(μ0H, T), show the presence of metal–semiconductor transition and a maximum magnetoresistance (MR) value of the order of 32% at magnetic field of 5 T. The phenomenological percolation model was used to study the conduction mechanism of the sample. It has been also shown that, from analyzing the temperature and magnetic field dependences of the electrical resistivity, it is possible to predict the behavior of the magnetization as well as the change of magnetic entropy near the phase transition temperature. The obtained agreement with experimental data for this analysis is quite reasonable.

Structural and transport properties of composite of La0.8Sr0.2MnO3 and BaTiO3 materials

We studied the effect of BaTiO3 phase on the structural, vibrational, and electrical properties of La0.8Sr0.2MnO3. The parent samples of La0.8Sr0.2MnO3, BaTiO3 and their composite (0.85) La0.8Sr0.2MnO3 + (0.15) BaTiO3 were synthesized by solid-state reaction route. Structural study using X-ray diffraction (XRD) for La0.8Sr0.2MnO3 phase revealed a rhombohedrally distorted (space group R3c) structure, while BaTiO3 compound was found to have crystallized in tetragonal structure (space group P4mm). The XRD results were verified using Rietveld refinement. The composite sample (0.85) La0.8Sr0.2MnO3 + (0.15) BaTiO3 display the presence of both of La0.8Sr0.2MnO3 and BaTiO3 phases. The addition of insulating BaTiO3 phase in the ferromagnetic metallic phase of La0.8Sr0.2MnO3 which exhibits well-characterized metal-to-insulator transition in the vicinity of 350 K enhances the resistivity and shifts the metal–insulator transition temperature TMI towards lower temperature. Further, with the application of magnetic field, resistivity of the composite sample is found to decrease and TMI in composite sample is observed to shift towards higher temperature. The magnetoresistance (MR) of composite sample (0.85) La0.8Sr0.2MnO3 + (0.15) BaTiO3 decreases monotonously in 200–300 K regime under magnetic field of 8 T. The analysis of electrical resistivity data in the metallic region (T TMI) is well described using Small polaron hopping (SPH) and Mott's variable range hopping (VRH) models.

Experimental and theoretical study on enhanced electrical properties of nickel-substituted La0.5Sr0.5CoO3−δ ceramics

The effect of Ni substitution on the thermal behavior, crystal structure, densification, and electrical properties of La0.5Sr0.5Co1–yNiyO3-δ (y = 0.00–0.08) (LSCN) ceramics was discussed based on experimental measurements and theoretical calculations to search for a ruthenium–free and lead–free conductive oxide for thick film resistors. Ceramics were synthesized by the solid–state reaction, and calculations were performed with first–principle density functional theory (DFT). Results showed that the replacement of Ni ion to Co ion could help decrease the densification temperature and enhance the densification level and improve the conductivity of LSCN. Theoretical calculations, including the crystal structure, bond population, total energy, and density of states (DOS), supported the experimental results well. The maximum conductivity of 3155 S/cm was achieved as y = 0.04 was sintered at 1200 °C, and the peak temperature coefficient of resistance (TCR) of 2405.7 ppm/°C occurred at y = 0.06.

Effect of annealing environments on structural and electrical properties of La0.5Nd0.5MnO3 manganites

In this communication, structural and electrical properties of rare earth La0.5Nd0.5MnO3 (LNMO) manganites have been studied under the effect of synthesis environments. Nanostructured LNMO samples were prepared by using cost–effective sol–gel method. In order to study the structural properties, θ–2θ X–ray diffraction (XRD) measurement was carried out, for all LNMO samples, at room temperature. Rietveld analysis was carried out to confirm the single phasic nature using fullprof software. The crystallite size was calculated using Scherer's formula. Frequency dependent dielectric response have been carried out using LCR meter in the frequency range of 20 Hz to 2 MHz at room temperature under the applied magnetic field both, H = 0 and 1T. Also, temperature dependent dipole response has been carried for all LNMO samples in the temperature range of 173K–253K. Relaxation mechanism and universal dielectric response (UDR) model have been discussed to understand the dielectric behavior of the samples. Overall, dielectric behavior has been understood in the context of role of size effects and oxygen vacancies in the lattice under the different magnetic field, process temperature and process environments.