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In this communication, structural and electrical properties have been discussed for chemically grown ZnO–LaMnO3 (ZnO–LMO) nanocomposites. Nanocomposites were prepared by mixing the different weights, i.e., ratios of ZnO to LMO, 100:0, 95:5, 90:10, 85:15, and 0:100 wt% of ZnO:LMO in their composite form. X-ray diffraction (XRD) measurement shows that all the pure and composite samples possess single-phase nature without any detectable impurity. Particle size and shape were identified using transmission electron microscopy (TEM) measurement. Frequency-dependent dielectric constant (e′), loss tangent (tanδ), real and imaginary parts of the electric modulus (M′ and M′′), and a.c. conductivity have been carried out at room temperature for all the samples. Dielectric behavior has been understood in the context of universal dielectric relaxation (UDR) model and relaxation mechanism fits well throughout the frequency range studied. Variation in a.c. conductivity has been discussed on the basis of Jonscher’s universal power law.

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.

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.

Nanocomposites consist of ZnO and La0.3Ca0.7MnO3 (LCMO) nanoparticles, prepared by cost effective sol–gel method, have been studied for their transport and magnetoresistance (MR) behaviors. Different ZnO nanoparticles contents (weight ratio) were mixed with LCMO nanostructured manganite to understand the possible interactions between ZnO and LCMO nanoparticles. X–ray diffraction (XRD) measurement was performed for all composites and structural quality was verified by performing Rietveld refinements. Variation in an average crystallite size for LCMO and ZnO nanoparticles in different composites has been discussed. Temperature dependent resistivity measurements under different applied magnetic fields suggest the semiconducting nature of all nanocomposites under all applied magnetic fields. Mott type variable range hopping (VRH) mechanism has been employed to understand the dependence of charge carrier localization in LCMO nanostructured manganite lattice on the applied magnetic field and ZnO nanoparticles content within the nanocomposites. Observed MR behavior has been understood under the influence of temperature and ZnO nanoparticles content in the context of spin polarized tunneling (SPT) and magnetic field induced improved conduction across the manganite lattice. Grain and grain boundary contributions to the MR behavior have been explained by using theoretical model fits to obtained MR data at different temperatures for all studied LCMO:ZnO nanocomposites. Magnetic nature of studied LCMO:ZnO nanocomposites has been understood by performing zero field cooled (ZFC) and field cooled (FC) measurement protocols based magnetization and magnetic isotherms measurements that confirm the coexisting magnetic phase in all studied nanocomposites. Magnetic nature has been understood on the basis of weakening of zener double exchange (ZDE) mechanism within the magnetic lattice of LCMO manganite and magnetic contribution from the free charge carriers within the ZnO clusters.

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 × 104 and 2 × 105 factors, respectively, as compared to pure LSMO. Value of TP is found to be suppressed by a factor of ~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.

Results of the studies on structural, dielectric constant (e′), Impedance (Z) and ac conductivity (σ) of sol–gel grown ZnO–SnO2 nanocomposites have been reported. X–ray diffraction (XRD) measurement reveals dual phase nature of all composites without any unwanted impurity phase. Particle size analyzer was used for establishing the nano scale order of both pure oxides. Various structural aspects of the studied nanocomposites have been discussed and correlated with ac conductivity variations with SnO2 content whereas dielectric response has been understood with the help of cole–cole model. Complex impedance spectroscopy has been understood on the basis of Nyquist plot. Frequency dependent ac conductivity strongly obeys the Jonscher's universal power law and understood on the basis of correlated barrier hopping (CBH) mechanism. Electrical properties are found to depend on temperature and frequency and have been discussed in the context of oxygen vacancies, defects, disorder and structural parameters.

In this communication, structural and electrical properties of rare earth oxides La2O3 (LO) and LaNdO3 (LNO) have been studied. To understand the structural properties of the LO and LNO samples, X-ray diffraction (XRD) measurement was carried out at room temperature. The XRD patterns have been analyzed by Rietveld refinement to confirm the single-phase nature of both the samples. The crystal structures of studied samples were created from the derived parameters of Rietveld parameters. The crystal size and lattice strain have been estimated using Williamson–Hall (W–H) plot analysis. Frequency-dependent dielectric constant and loss tangent have been studied for a frequency range of 20 Hz to 2 MHz. To estimate the relaxation time and contribution of the charge carriers in the studied samples, relaxation mechanism and universal dielectric response (UDR) model have been employed. The ac conductivity measurements were carried out for the same frequency range (i.e., 20 Hz to 2 MHz) which has been understood on the basis of Jonscher’s power law. The barrier height has been calculated by fitting the power law. Frequency-dependent impedance behavior has been discussed in the context of grains and grain boundaries for both the samples under study.

In this communication, we report the dielectric response of pulsed laser deposition (PLD) grown Y0·95Sr0·05MnO3 (YSMO) manganite thin films (having two different thickness i.e. ~200 & 300 nm) on single crystalline Nb:SrTiO3 (SNTO) substrates. These films were irradiated by 200 MeV Ag+15 ions with different ion fluence. Structural studies, using X–ray diffraction (XRD) measurement, reveal single phase nature without any detectable impurity within the measurement range studied. Atomic force microscopy (AFM) images reveal that grain size and grain boundaries are highly influenced by the SHI ion fluences and film's thickness. Variations in dielectric constant with frequency, ion fluence, and film thickness have been discussed in the context of structural strain at the film–substrate interface, defect density and structural disorder in films. To understand the dielectric response of all the films with the help of universal dielectric response (UDR) model while cole-cole plots have been studied for the relaxation mechanisms.

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.

In the present communication, we report the results on the structural and electrical studies on nanostructured pure (ZnO) and Vanadium (V) doped Zn0.95V0.05O samples synthesized using low cost Sol-Gel technique. To understand the structural properties and their dependence on V substitution, X–Ray diffraction (XRD) measurement was carried out for both the samples understudy. XRD results reveal the single phasic wurtzite nature of both the samples showing hexagonal unit cell structure. A minor phase of ZnV2O6 is observed in V doped ZnO sample. Improved dielectric permittivity, enhanced ac conductivity (σac) and suppression in impedance have been discussed on the basis of structural modifications by the substitution of V in ZnO, enhanced charge carrier concentration, charge carrier polarization and correlated barrier hopping due to the localized state.