The present study reports the structural and magnetoelectrical properties of sol-gel SYNTHESIZED LA(0.6)GD(0.1)CA(0.15)SR(0.15)MNO(3) (LGCSMO) NANOPARTICLES. X-RAY DIFFRACTION (XRD) analysis confirms the formation of a single-phase structure without detectable impurities. The crystallite size, estimated using Scherrer's formula (crystalline size, CS = 0.9 lambda/beta cos theta), is found to be approximately 31.15 nm. Structural phase purity is further validated through Rietveld refinement using FULLPROF software. Scanning electron microscopy (SEM) reveals particle growth and surface morphology. Frequency-dependent electrical measurements (20 Hz-2 MHz) carried out under 0 and 1 T magnetic fields at room temperature indicate that impedance and reactance increase, while resistance decreases with increasing frequency. Conversely, all three parameters - impedance, resistance and reactance - decrease upon the application of a magnetic field. The observed magnetoresistance (MR), magnetoreactance (MX) and magnetoimpedance (MI) suggest the presence of magnetoelectric coupling in LGCSMO nanoparticles, highlighting their potential for spintronic applications.

A comparative investigation on the magnetic and transport properties of divalent (Ca+2 and Sr+2) doped YMnO3 thin films is reported, Y(0.95)A(0.05)MnO(3,) (A = Ca, Sr) designated as Y0.95Sr0.05MnO3 (YSMO) and Y0.95Ca0.05MnO3 (YCMO) respectively, were deposited on single crystalline Nb: SrTiO3 (SNTO) substrate using pulsed laser deposition (PLD) the film has an average thickness of similar to 300 nm. X-ray Diffraction (XRD) analysis confirms phase purity and reveals an orthorhombic unit cell structure for both films Magnetic properties were studied using Zero field cooled (ZFC) and field cooled (FC) magnetization measurement across varying temperatures. Distinct differences in magnetic and transport behaviour were observed influenced by temperature, magnetic field, ionic radius of dopant and lattice mismatch between film and substrate. YSMO exhibits a higher magnetic moment compared to YCMO, with more pronounced features in magnetic hysteresis (M - H) loops. Time dependent current-voltage(I-V) characteristics reveal diode-like behaviour in both forward and reverse bias, indicating potential for electronic device applications.

In the present communication, the electrical transport properties have been investigated for manganite-based composites consisting of different weight fractions of nanoparticles of LaMnO3 (LMO) and polycrystalline La0.7Ca0.3MnO3 (LCMO). A complex phase separation scenario has been proposed to understand the hysteretic resistive nature exhibited by manganite matrix composites. The role of complex phase separation has been discussed for the manganite composite resistivity and temperature coefficient of resistance (TCR) dependence on temperature, thermal cycle, current and LMO content as well as their sensitivity for voltage and current have also been examined. Observed electric pulse-induced resistance (EPIR) switching in these composites under different applied voltages and magnetic fields have been understood based on a complex phase separation scenario and the formation-rupture of conducting filamentary paths. Tuning of magnetic field-dependent resistance and magnetoresistance (MR) with the influence of different resistance states of LMO-LCMO composites has been understood in depth.

In this communication, we report the magnetic and transport properties of pulsed laser deposition (PLD) grown with 5% Ca and Sr doped YMnO3 (Y0.95A0.05MnO3 (YAMO)), where A=Ca or Sr grown on the single crystalline Nb:SrTiO3 (SNTO) substrate. PLD grown thin films possesses the thickness of ~ 300 nm each. For checking phase purity, x–ray diffraction (XRD) was measured for both the studied films possess orthorhombic unit cell structure. The magnetic moment has been observed by ZFC and FC measurement by different temperatures. Both of these device exhibit different magnetic and transport properties and is mostly affected by external parameters like temperature, magnetic field, ionic size of doped element and structural mismatch between film and substrates. While the magnetic moment of YSCMO is larger than that of YCMO, its magnetic properties in the hysteresis loops (M-H) are also more remarkable that those of YSMO. A time dependent I–V characteristic explains the junction diode behaviour in forward and reverse bias.

Pure metal oxides ZnO and TiO 2 and their composite ZnO:TiO 2 (1:1 weight ratio) were prepared by using conventional solid-state reaction technique. X-ray diffraction (XRD) measurement reveals the hexagonal phase for ZnO, whereas anatase phase has been identified for TiO 2 sample. Rietveld refinements have been performed using FULLPROF code to verify the structural phase purity for all three samples. No clear evidence of other mixed phase can be realized for ZnO:TiO 2 composite. Field emission scanning electron microscopy and particle size analyzer measurements provide modifications in the grain size and particle size for pure metal oxides and their composite sample. Optical behaviours of all samples have been investigated using UV–visible absorption spectroscopy, where it is evident that UV absorption gets improved for ZnO:TiO 2 composite that can be advantageous application to reduce UV light hazards. Bandgap value for the composite is found to be higher than both the pure oxides, which verifies the surface modification approach in the lattice of the composite. Room temperature dielectric permittivity gets reduced in accordance with frequency, indicating a disability of dipoles to follow a higher electric field. It is also observed that the dielectric constant of the composite is found to be lower than both the pure ZnO and TiO 2 samples. Investigations on dielectric loss indicate its lower values experienced by composite sample.

In the present communication, structural, microstructural and electrical properties of La(0.5)Nd(0.2)A(0.3)MnO(3) (LNCMO) and La(0.5)Nd(0.2)A(0.3)MnO(3) (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 degrees 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. (C) 2021 Elsevier B.V. All rights reserved.

Composites of polycrystalline La0.7Sr0.3MnO3 (LSMO) and nanoparticles of BiFeO3 (BFO) have been prepared in their particles-matrix LSMO(1-x)-BFO(x) form. Addition of 15 and 20 wt% BFO nanoparticles within the LSMO manganite lattice enhances the resistivity by 2 x 10(4) and 2 x 10(5) factors, respectively, as compared to pure LSMO. Value of T-P is found to be suppressed by a factor of similar to 4.5 in 20 wt% BFO incorporated LSMO manganite as compared to pure one. Different charge transport models have been employed to understand the charge conduction mechanism. Complex mechanisms have been discussed for obtained magnetoresistance (MR) isotherms. At 5 K, one can find almost double extrinsic MR in 20 wt% BFO added LSMO composite as compared to pure LSMO whereas at 300 K, pure LSMO shows 4 times larger intrinsic MR as compared to 20 wt% BFO added LSMO composite.

We have investigated the bipolar resistive switching of Y0.95Ca0.05MnO3 (YCMO) thin film on Si substrate using pulsed laser deposition. Simulation of Mn L3,2 near-edge X-ray absorption fine structure has been executed by CTM4XAS to corroborate the presence of a mixed-valence state of Mn ions and oxygen vacancies. The charge transport in the film is described by the space charge limited mechanism. Murgatroyd and space charge limited mechanism relations are used to calculate the mobility and other switching parameters at high resistance state. With a decrease in the switching layer (near to positively biased electrode) thickness, better resistive switching was observed. This work indicates that the localized switching thickness and temperature strongly affect the resistive switching of the YCMO film.

Micronsized matrix of La0.7Ca0.3MnO3 (LCMO) was synthesized by solid state reaction route whereas BiFeO3 (BFO) nanoparticles were synthesized by sol–gel method. Different contents of BFO nanoparticles were incorporated into the micronsized LCMO matrix lattice to prepare their composites. X–ray diffraction (XRD) measurement was performed to understand the crystalline phases present in these composites. Structural investigation suggests the dual phase nature of all the composites (consist of LCMO and BFO phases). No extra phases other than two, LCMO and BFO phases, can be found in the XRD patterns. Transport and magnetotransport properties have been studied by recording the temperature and magnetic field dependent resistance of the composites. Resistivity behavior shows that all the composites exhibit metal to insulator transition at TP which is highly sensitive to magnetic field and BFO content. The values of resistivity are also influenced by the applied magnetic field and BFO content in the composites. Since all three composites with different BFO contents (i.e. 0, 10 and 20%) exhibit low temperature resistivity minimum behavior, various theoretical models and mechanisms have been employed to understand the responsible charge conduction across the composite lattices. All composites exhibit negative magnetoresistance (MR) which has been discussed in detail on the basis of role of high resistive nanoparticles of BFO incorporated within the micronsized LCMO matrix.

In this communication, we report the results of the studies on structural and transport properties of monovalent Na+ doped La1–xNaxMnO3 (LNMO; x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30) manganites synthesized by conventional ceramic method. X-ray diffraction (XRD) and Rietveld refinements reveal the single phasic nature of LNMO manganites without any detectable impurity within the measurement range. Temperature dependent resistivity, under different applied magnetic fields, has been performed on LNMO samples. Samples understudy exhibit metal to insulator (semiconductor) transition at temperature TP which is strongly influenced by the substitution of Na+ at La3+ site. r – T plots also exhibit resistivity upturn behavior at low temperature well below 40K under all the applied fields. Variation in TP and resistivity has been discussed in the context of the competition between the transport favoring tolerance factor and zener double exchange (ZDE) mechanism and transport degrading Jahn–Teller (JT) and size variance effects. In order to understand the mechanisms responsible for the charge transport in metallic and semiconducting regions and to explore the possible electronic processes responsible for the observed low temperature resistivity minima in all the presently studied LNMO manganites, various models have been employed. It has been found that VRH mechanism gets successfully fitted to the resistivity data in the semiconducting region while ZDE polynomial law is responsible for the charge conduction in metallic region for all the presently studied LNMO samples. A strong dependence of activation energy on the Na+ – content as well as applied magnetic field has been discussed in the context of variation and interrelations between the structural parameters. Charge conduction in metallic region has been discussed in the light of electron–phonon interactions which is influenced by the Na+ – content and applied magnetic field. Electrostatic blockade model has been employed to understand the low temperature resistivity minima behavior. Blocking energy for the charge carriers shows a dependence on the magnetic energy provided to the charge carriers. Present study can be useful to understand and to control the charge conduction in the manganites and hence to design the manganite based thin film devices for various spintronic applications.

In this communication, structure and charge, conduction mechanisms have been understood for sol–gel-grown nanostructured La 0.6 Nd 0.1 Sr 0.3 MnO 3 (LNSMO) manganites prepared at different process temperatures under air and oxygen environments. Obtained X-ray diffraction patterns of all the samples were analysed using Rietveld refinements and obtained structural lattice parameters have been discussed in correlation with resistivity behaviour of the samples. Observed low temperature resistivity upturn behaviour has been examined in the context of electron–electron scattering mechanism. Metallic and insulating/semiconducting behaviours of all the nanostructured LNSMO manganites have been understood by using various models and mechanisms. Magnetoresistance isotherms have also been theoretically fitted and separate grain and grain boundary contributions have been studied for LNSMO manganite samples. All obtained fitting parameters have been discussed in the context of role of applied magnetic field, process temperature and annealing environment.

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, theta-2 theta 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.

Structural properties and charge conduction mechanisms in La0.6Pr0.1Ca0.3MnO3 (LPCMO) manganite has been studied. Presently studied LPCMO manganite was successfully synthesized by solid state reaction method. Structural studies using X–ray diffraction (XRD) measurement at room temperature confirm single phase orthorhombic unit cell without any impurity. A methodical investigation of electrical resistivity was undertaken, for both, as a function of temperature as well as magnetic field. It is observed that LPCMO sample shows metal to insulator transition at TP as well as low resistivity upturn around 30K. Various models and mechanisms have been studied to verify the charge transport properties for low temperature upturn, metallic behavior as well as insulating/semiconducting behavior. Magnetoresistance (MR) behaviors at different temperatures have been theoretically understood on the basis of contributions from grain and grain boundaries.

In this communication, we report the results of the investigations on the structural and electrical properties of ZnO:Zn0.95Al0.05O (ZnO:ZAO) nanoparticles matrix composites, prepared with ZnO nanoparticles as fillers and ZAO as a matrix using sol-gel and solid state reaction method, respectively. In order to study the structural properties, theta-2 theta X-ray diffraction (XRD) measurement was performed at room temperature using CuK alpha radiation. The crystallite size was calculated using Scherer's formula. Frequency dependent dielectric, ac conductivity and impedance have been carried out using high precision LCR meter in the frequency range of 20 Hz to 2 MHz. Dielectric constant was also recorded for higher frequency range up to 3 GHz for all the samples and comparison based discussion has been represented for the possible relaxation processes at lower and higher frequency ranges. Relaxation mechanism and universal dielectric relaxation (UDR) model have been fitted to dielectric behavior of the samples understudy throughout the frequency range (both, lower and higher). Frequency dependent variation in ac conductivity has been discussed on the basis of correlated barrier hopping (CBH) mechanism for presently studied samples. Role of ZnO fillers content in the composites has also been discussed for the observed variations in impedance with frequency. Also, temperature (25-200 degrees C) dependent dielectric, conductivity and impedance were studied for all the samples understudy. Variations in estimated activation energy (E-a) with ZnO fillers content and frequency have been discussed in detail. (C) 2019 Elsevier B.V. All rights reserved.

In this communication, we report the results of the electrical studies on La1-xPrxMnO3 (LPMO; 0 <= x <= 1) single valent manganites synthesized by conventional solid state reaction route. Structural studies reveal a single phasic nature of all LPMO samples having orthorhombic unit cell structure without any detectable impurity or structural phase transformation. Dielectric constant and impedance are found to increase while ac conductivity gets suppressed effectively upon increase in Pr content (x). This has been discussed in detail on the basis of structural distortion and tolerance factor in LPMO manganites. Temperature dependent dielectric behavior indicates an anomaly near respective magnetic transition temperature. Obtained dielectric and ac conductivity results have been theoretically fitted using relaxation formula and power law, respectively. Obtained fitting parameters have been discussed in the context of various structural aspects of LPMO manganites.

ZnO based particle – matrix composites were studied for their electrical properties. ZnO nanoparticles were prepared by sol-gel technique whereas Zn0.95Al0.05O micron sized matrix was prepared by solid state reaction route. Different contents of ZnO nanoparticles (0.5,10,15 and 20 wt%) were added in the microsized Zn0.95Al0.05O matrix. All Pure and composite samples were characterized for their structural aspects by performing X-ray diffraction (XRD) measurements. XRD results reveal the single phase nature of pure samples whereas composites do not possess any extra phases. Frequency dependent resistance and reactance was recorded for all Pure and composite samples understudy. It is found that resistance as well as reactance (with negative sign) decrease with increase in frequency. Variations in resistance as well as reactance with ZnO nanoparticles content have been discussed in detail.

In the present communication, nanostructured Bi0.9Nd0.1FeO3 (BNFO) multiferroics have been successfully synthesized by sol–gel method and finally sintered at different temperatures. In order to investigate the structural properties, X-ray diffraction (XRD) measurement was carried out at room temperature that reveals the single phase of BNFO samples. For microstructural behaviors and granular morphology of nanostructures, scanning electron microscopy (SEM) was performed. It is observed that grain morphology gets improved with increase in sintering temperature. For elemental analysis, energy dispersive X-ray analysis (EDAX) was carried out for all BNFO samples, which reveal appropriate doping of Nd at Bi site in BNFO samples. Frequency dependent dielectric measurements show that the dielectric constant increases with increase in sintering temperature, which has been understood on the basis granular morphology of the samples. Frequency dependent dielectric behavior follows the universal dielectric response (UDR) model for all BNFO samples. Magnetodielectric (MD) effect has been investigated in the frequency range of 20 Hz–2 MHz, which shows a strong dependence of sintering temperature and granular morphology of the samples. AC conductivity was found to obey the Jonscher’s universal power law, which suggests the correlated barrier hopping (CBH) process as a responsible mechanism for charge conduction across the BNFO lattices.

Herein, the bipolar resistive switching of Y0.95Sr0.05MnO3 (YSMO) film grown on a Si substrate by pulsed laser deposition is reported. The mixed valent state of Mn ions with the presence of oxygen vacancies is confirmed by near‐edge X–ray absorption fine structure. The temperature‐dependent mobility and other switching parameters are extracted using Murgatroyd expression and a space charge–limited mechanism in the high‐resistance state. The YSMO thin film shows better resistive switching as the switching layer (a layer close to a positively biased electrode) thickness decreases. The bipolar resistive switching of the film suggests a strong dependence on localized switching thickness and temperature.

In this communication, we report the results of the structural and transport studies performed on ZnO/La0.7Ca0.3MnO3/LaAlO3 (ZnO//LAO) heterostructure grown using simple, low cost, vacuum free and environment friendly chemical solution deposition (CSD) method. ZnO is found to be polycrystalline while LCMO film orientations suggest its single crystalline growth, parallel with the crystallographic orientations of LAO substrate. Double peak transition behavior, observed in the R – T, has been discussed on the basis of phase coexistence scenario. Charge transport behavior and charge conduction mechanisms have been investigated by performing current–voltage (I–V) characteristics at different temperatures. Various electronic and thermal processes have been proposed as sources of backward diode like characteristics observed across ZnO/LCMO interface. Complex variations in electroresistance (ER) have been discussed on the basis of charge injection, depletion region modifications, tunneling, breakdown and thermal processes.