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The topotactic phase transition in the transition-metal oxides via redox reactions has wide-ranging applications in solid oxide fuel cells, neuromorphic computations, mottronics, and memory devices...

BaBiO3(BBO) is known to be a valence-skipping perovskite, which avoids the metallic state through charge disproportionation (CD), the mechanism of which is still unresolved. A novel mechanism for CD is presented here in the covalent limit using a molecular orbital (MO) picture under two scenarios: (case i) Bi 6sp-O 2p and (case ii) Bi 6p-O 2p hybridizations that favor 5+ and 3+ states, respectively. The proposed model is further validated by using a combinatorial approach of X-ray spectroscopic experiments and first-principle calculations. The bulk X-ray photoemission spectrum reveals that, at room temperature, the CD is dynamic in nature, whereas, at 200 K, it approaches a quasi-static limit. Under compressive strain, the octahedral breathing mode is damped and drives the system to a quasi-static limit even at room temperature, giving rise to asymmetric CD.

The microstructures and interfaces of two-phase vertically aligned nanocomposite (VAN) thin films play a key role in the design of spintronic device architectures and their multifunctional properti...

We synthesized mesoporous cobalt titanate (CTO) microrods via the sol–gel method as an outstanding working electrode for the supercapacitor. The mesoporous CTO microrods were amassed in hexagonal shapes of an average width of ∼670 nm, and were composed of nanoparticles of average diameter ∼41 nm. The well crystalline CTO microrods of the hexagonal phase to the R space group possessed an average pore size distribution of 3.92 nm throughout the microrod. The mesoporous CTO microrods with increased textural boundaries played a vital role in the diffusion of ions, and they provided a specific capacitance of 608.4 F g−1 and a specific power of 4835.7 W kg−1 and a specific energy of 9.77 W h kg−1 in an aqueous 2 M KOH electrolyte, which was remarkably better than those of Ti, La, Cr, Fe, Ni, and Sr-based perovskites or their mixed heterostructures supplemented by metal oxides as an impurity. Furthermore, the diffusion-controlled access to the OH− ions (0.27 μs) deep inside the microrod conveyed high stability, a long life cycle for up to 1950 continuous charging–discharging cycles, and excellent capacitance retention of 82.3%. Overall, the mesoporous CTO shows its potential as an electrode for a long-cycle supercapacitor, and provides opportunities for additional enhancement after developing the core–shell hetero-architecture with other metal oxide materials such as MnO2, and TiO2.

Heterostructures have delivered phenomenal photoelectrochemical performance owing to their excellent physicochemical properties. We report on the utilization of controlled Au@ZnO nano-heteroarchitectures for efficient water splitting. The ZnO nanowires of an average length and a diameter of ∼5–6 μm and 120 nm, respectively, synthesized by the hydrothermal method were subjected to the controlled decoration of Au nanoparticles of diameter ∼20 nm. The cubic crystalline Au nanoparticles were decorated on the hexagonal wurtzite ZnO nanowires under a controlled reaction time. A 12 h reaction time has resulted in the uniform decoration of Au nanoparticles along the surface of ZnO nanowires, and a further increase in the reaction time ensured their agglomeration in the array of ZnO nanowires. XPS analysis revealed the existence of pure metallic Au on ZnO nanowires without altering the stoichiometry. The Au@ZnO nano-heteroarchitecture with a 12 h reaction time delivered a maximum photocurrent density of 1.04 A cm−2, which is a 52-fold increase than that of pristine ZnO nanowires. The ABPE value is 0.59%, which is approximately five-fold higher than that of the pristine ZnO nanowires. This reveals that the controlled decoration of Au nanoparticles along the surface of ZnO nanowires has altered the Fermi energy position significantly and facilitated the injection of hot electrons from the SP state into the conduction band of ZnO, effectively.

High-quality growth of MoS

This paper reports the spectroscopic investigation of Ba3Zr2O7 phosphors. A series of Ba3Zr2O7: Eu3+ with the different molar concentrations (0–4 mol.%) of europium (Eu3+) ion is synthesized by the solution combustion method. The synthesized powders are characterized systematically using X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, and ultraviolet–visible spectroscopy. X-ray diffraction results indicate that the synthesized powder has a tetragonal crystal structure. X-ray photoelectron spectroscopy is used to study the elemental composition of the synthesized phosphor. Field emission scanning electron microscopy result reveals that non-uniform morphology is formed. Photoluminescence spectroscopy result shows several emission peaks due to electronic transitions of Eu3+ ion, and the dominant peak is observed at 613 nm due to electric dipole transition 5D0 → 7F2. CIE coordinates of Eu3+-activated Ba3Zr2O7 phosphor is found to be (x = 0.64, y = 0.36) which gives bright red emission. The optical band gap of the phosphors is obtained from the diffuse reflectance spectrum and found in the range of 4.62–4.83 eV.

Structural, dielectric and magnetic properties of nano-size polycrystalline, La2CuMnO6 (LCM) samples were studied in the temperature range 80 K to 300 K. Orthorhombic single phase with space group 'Pnma' was confirmed by Rietveld refinement of XRD peaks. The small-polaron driven dielectric dispersion showed relaxation peaks in the vicinity of low-temperatures. The X-ray absorption spectroscopy (XAS) confirmed the charge states of Cu (2+) and Mn (4+) ions. DC-resistivity analysis supported the thermally activated conduction for high temperature and the variable range hoping (VRH) mechanism of conduction at low-temperature. The deviation of super-exchange angles between B-site cations from an ideal 180º value produced non-collinearity in the antiferromagnetic response of this ceramic and was confirmed canted antiferromagnetic behaviour. Positive Curie temperature along with finite coercivity indicated that the super-exchange interaction between Cu2+ and Mn4+ ions influenced the magnetic behaviour of this ceramics and showed a heterogenous magnetic response.

Eu3+ doped BaZrO3 thin films were deposited on quartz substrates in a wide range of oxygen pressure (1–300 mTorr), using Pulsed laser deposition technique. X-ray diffraction pattern showed the different growth orientation of the films with oxygen pressure ( P O 2 ) . The different growth mechanisms were drawn to explanin the thin films growth mechanism at the different oxygen pressure. Time of flight secondary ion mass spectroscopy analysis exhibited homogeneous distribution of all the elements throughout the depth of the films. The depth profile anaylsis revealed sharp interface at the low P O 2 and broad intermixing region of the films with the substrate at low P O 2 . Transmittance spectra revealed the different optical bandgap with different P O 2 . Excitation spectra showed a broad absorption band centered at 260 nm due to the absorption in the defect states. The emission spectra showed intense emission at 597 nm corresponding to the 5D0→7F1 transition of Eu3+. Apart from this, a broad blue-green emission was observed centered at 440 nm due to the trap levels associated with the oxygen vacancy below the conduction band. The energy transfer mechanism between the host to Eu3+ ion was described via a defect state process. Colour coordintes of the emission spectra showed that colour emission of thin films can be tuned by varying the oxygen pressure. The short-excited state lifetime and high value of internal quantum efficiency make these films potential candidates for light emitting diode application.

In this paper, MoSe2 nanoflakes on carbon cloth (MS-C) and MoSe2 powder (MS-P) were synthesized by facile hydrothermal route. The synthesized MoSe2 nanoflakes, owing to their high aspect ratio, are envisaged as potential candidates for field emitters. Accordingly, field emission (FE) characteristics of MoSe2 nanoflakes were investigated at the base pressure of 1 × 10-8 mbar. The FE properties were studied at three different anode-cathode separations (500, 1000 and 1500 μm). The observed values of turn-on and threshold fields are comparable to those exhibited by nanostructures and nano-composites of other TMDs. Moreover, the MS-C emitter showed competency to deliver very high emission current density of 5.372 mA/cm2 at an applied electric field of 8 V/μm. The MS-C emitter exhibited good emission stability at pre-set value of 100 μA and hardly any degradation in emission current was noticed over duration of 10 h. The use of carbon cloth as a substrate is two-fold advantageous, a substrate having very good electrical conductivity and mechanical flexibility. The observed results imply that the present synthesis protocol (carbon cloth as substrate and hydrothermal route) can be efficiently employed to fabricate flexible field emitters for practical applications in vacuum micro/nanoelectronic devices.

Here, we present the reduction of the graphene oxide (GO) sheets by means of the two reducing agents, i.e., ascorbic acid and lemon juice. As-prepared carbonaceous substances (rGO-AA and rGO-Lemon)...

We report the effect of simultaneous doping of three elements aluminum (Al), gallium (Ga) and indium (In), in ZnO nanostructures on its transmission, conductivity, and stability. The triply doped ZnO nanostructures have been synthesized using co-precipitation method and the material has been characterized by various techniques. The results are compared with the undoped ZnO as well as ZnO doped with individual elements (i.e., Al/Ga/In). All the samples have been found possessing hexagonal wurtzite structure. The transparency, conductivity as well as stability (when exposed to high temperature and humidity) of the triply doped ZnO are found better than individually doped ZnO. Our results suggest that doping of three elements may give rise to significant improvement in the properties (transmission, conductivity, and stability), as required for transparent conductive oxide (TCO) applications.

The thin films of Ga doped hematite (α-Fe2O3) were grown on p-Si substrate using Pulsed Laser Deposition technique. The as-grown films indicated crystalline peaks of rhombohedral structure. The films exhibited enhancement of ferromagnetic properties. The reduction of dimensionality of the materials in thin films (2D) has shown unusual magnetic spin order and exchange bias effect at temperatures

We studied the effect of 200 MeV Ag+15 ion irradiation on structural, magnetic, and electrical transport properties of LaCoO3 thin films. LaCoO3 thin films deposited on SrTiO3 (100) single crystal substrates using the Pulsed Laser Deposition method were found to be grown highly c-axis oriented. Structural studies reveal that irradiation affects the crystalline nature of film but retains the oriented single-phase growth. In addition, a systematic fluence dependent variation in the out-of-plane tensile strain has also been confirmed. The surface modifications after irradiations have been quantified through the measurements like average grain size, surface roughness for each of ion fluence by AFM studies. The electrical conduction has been found to be governed by disorder controlled localization of charge carriers. Magnetic studies reveal the variation in magnetic moment and appearance of FM ordering at room temperature upon Swift heavy ion irradiation.

We report the experimental study of the nonlinear optical properties in pulsed laser deposited undoped and Al doped NiO thin films at an excitation energy (≈1.95 eV). Crystalline properties of thin films were investigated using grazing incidence X-ray diffraction (GIXRD) technique confirmed the cubic structure of the grown thin films. The surface morphology of the grown thin films were studied using atomic force microscopy (AFM). It demonstrated the spherical and rectangular shape of grains for undoped and Al doped NiO thin films, respectively. We performed Z-scan technique to determine the nonlinear optical properties of the thin films. We obtain positive and negative absorptive nonlinearity in undoped and Al doped NiO thin films, respectively. The sign reversal of optical nonlinearity suggests the utility of the grown films for optoelectronic device application.

Here, we report extraordinary field emission properties from one pot synthesized aligned carbon nanotubes endowed with related Fe nanoparticles (NPs). The CNT configuration is in the form of a carbon hollow cylinder (CHC) with CNTs radially aligned towards the CHC axis. The structure generates electron field emission properties such as an ultralow turn on field (0.35 V μm−1 at 10 μA cm−2), a low threshold field (0.41 V μm−1 at 100 μA cm−2) and a high field emission current density (7.71 mA cm−2 at 0.78 V μm−1). It also exhibits multi-fold improvement in the field enhancement factor (1.34 × 104) with highly stable current emission at 100 μA measured for 14 h. No post synthesis treatment is required for enhanced field emission characteristics. The growth related Fe NPs assist in lowering the work function and hence enhancing the field emission properties. The possibility of assembling nano-structured field emitters into macroscale architectures suggests new prospects for next generation three dimensional electron sources.

Herein, CuInTe2 (CIT) thin films with faceted nanorod-like morphology have been synthesized on a flexible molybdenum foil using a water-based low-cost electrodeposition technique. The co-deposition potential for CIT was optimized using cyclic voltammetry with respect to that of the Ag/AgCl reference electrode, and films were deposited from −0.6 V to −0.9 V at the working temperature of 75 °C. The as-prepared CIT films exhibited an amorphous nature, whereas the RTP-annealed films exhibited a highly crystalline chalcopyrite nature as a function of the growth potential. A red shift was observed in the Raman spectra of the as-deposited films that shifted towards the original position upon annealing. The Cu/In ratio obtained by the EDS analysis was found to decrease systematically upon increasing the growth potential. X-ray photoelectron spectroscopy (XPS) studies revealed the presence of Cu+, Cu2+ satellites, In3+, Te2−, and Te4+ states of Cu, In, and Te. The field emission study showed a maximum current density of 1.74 mA cm−2, which was attainable at an applied electric field of 1.5 V μm−1. The turn-on field was found to be 0.92 V μm−1, comparable to that of the carbon nanofibres. The emitter exhibited stable electron emission over a period of 3 hours. The faceted CIT nanorods with columnar growth are a potential candidate for application as an electron source, and herein, the field emission of CIT nanorods is reported for the first time.

We have presented experimental results addressing the origin of spin valve (SV) magneto-resistance (MR), in both injection and tunnel conduction regimes, in our fabricated Fe3O4 (111)/Alq3/Co SV device. Experimental evidences have shown that any alternative MR process, such as ‘tunneling anisotropic MR’ is not at the origin of this SV MR. Spin resolved density of states of electrodes indicate that both the conduction mechanisms induce different spin dependent scattering which inturn modify the MR signal of the device. This modification helped in maintaining a non-monotonous quenching of MR signal with increase in temperature. We have also proposed a phenomenological model for device operation where the concept of charge gap modification at Fermi level across Verwey transition is envisaged to offer this unique scenario of tuning the conduction mode and hence MR in this ferrite based organic SV. The model is also supported by an established theoretical study which considers high temperature phonon assisted tunneling through defect states at electrode–organic interface of the device.

SrSnO3 is a potential candidate for the perovskite-structured transparent electrode for many optoelectronic devices, especially for recently developed perovskite solar cells. La-doped SrSnO3 thin films were deposited using pulsed laser deposition on SrTiO3 (STO) substrate to study its structural and electrical properties. This study reveals that Lanthanum is a promising dopant for SrSnO3. Results of the Rutherford backscattering experiment showed that the oxygen vacancies are increasing with strain on La doping. X-ray diffraction measurements revealed the increase in strain with La-doping which was the reason for the increase in oxygen vacancies. The charge-neutrality was maintained within the films by the reduction of Sn4+ to Sn2+. The coexistence of two tin charge states (4+ and 2+) facilitated the hopping mechanism of the conduction. It was observed that La-doping reduced the electrical resistivity by 7 orders of magnitude with no significant change in its structure. Results obtained from X-ray absorption spectra are also consistent with these results.

The electronic structure of Pulsed Laser Deposited (PLD) ZnO, Zn0.95Fe0.05O (ZFO), Zn0.98Al0.02O (ZAO) and Zn0.93Fe0.05Al0.02O (ZFAO) films were investigated by Photoelectron spectroscopy and X-ray absorption spectroscopy. X-ray diffraction and ϕ-scan measurements show epitaxial c-directional growth of the films. Temperature dependent magnetization and M-H loop measurements show the presence of room temperature magnetic ordering in all the films. Fittings of Fe 2p XPS and Fe L3,2 −edge XAS of ZFO and ZFAO films show the presence of Fe, in both, Fe+2 and Fe+3 states in tetrahedral symmetry. Valence band spectra in resonance mode show resonance photon energy at 56 eV showing the presence of Fe2+ state (∼2 eV) near the Fermi level. A significant effect of Fe and Al doping on the spectral shape of O K-edge XAS was observed. Results of the Spectroscopic studies reveal that, ferromagnetism in the films is due to the contribution of oxygen deficiency which increases the number of charge carriers that take part in the exchange interaction. Al co-doping with Fe (in ZFAO) results in the enhancement of saturation magnetization by increase in the carrier-mediated ferromagnetic exchange interaction.

Electric-field controlled magnetism is a potential way to realize strong magneto-electric (ME) coupling for nonvolatile memory applications. The electric field induced nonvolatile modulated magnetization was obtained in NiFe2O4/SrRuO3/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMN-PT) thin film heterostructures. The collective effect of charge and strain significantly modified the magnetization of the NiFe2O4 layer in NiFe2O4/SrRuO3/PMN-PT heterostructures. The analysis of XMCD data establishes that the cation (Fe3+/Ni2+) redistribution occurs on tetrahedral and octahedral sites in the electric field poled NiFe2O4 films, confirming the coupling between magnetism and ferroelectric properties. The films demonstrate repeatable switching of sign of ME output voltage α (α = dP/dH) in response to the applied positive and negative electric pulse, which can be used to store binary information in the nonvolatile manner. The electric-field-controlled switching of α in thin films offers an energy-efficient approach for low-power-consumption nonvolatile memory devices.

The spin-blockade phenomena occur in the charge-ordered systems because of the non-conservation of the spin-states of the charges across the charge hopping process. Here, we have investigated the validation of the spin-blockade phenomena in a different kind of charge-ordered system, viz. charge-disproportionated SrCoO2.5 thin film, where O-2p hole is the key parameter for such charge-ordering. It is observed with the help of the polarization-dependent O K-edge x-ray absorption spectroscopy that the spin-blockade increases with the decrease in charge-disproportionation vis-a-vis O-2p hole density in the SrCoO2.5 films. The spin-blockade has been realized in terms of the lowest energy charge fluctuation energetics in the SrCoO2.5 films. Our results provide a fundamental understanding of the spin-blockade phenomena in both the usual charge-ordered and unusual charge-disproportionated systems, which would lead to a path forward toward novel material designing.

The origin of the magnetic interaction in SrCoO2.75 and SrCoO3 thin films has been investigated with the help of their experimental valence band (VB) and the conduction band (CB) at room temperature. The ultraviolet photoemission spectroscopy and the O K-edge X-ray absorption spectroscopy were used to probe the VB and CB of the films respectively. It is found that the negative charge transfer energy (Δ) is contributing to the lowest energy charge fluctuations for the double-exchange ferromagnetic interaction in the systems which is larger in SrCoO2.75 film than SrCoO3 film. The magnetic exchange interactions have been realized from a model derived from the combined VB-CB spectra and the Co L-edge absorption spectra. These results offer a valuable inside into the correlation between the microscopic electronic structure and the macroscopic magnetization in the negative Δ double-exchange ferromagnetic oxides.

La0.5Sr0.5CoO3−δ system displaying coexistence of metallicity and ferromagnetism, and the interplay between distinct spin states of Co ions has gained significant attention from the fundamental as well as the applications point of view. In this regard, the effect of V5+ doping on the dynamics of spin and oxidation states of Co ions in the La0.5Sr0.5CoO3−δ system has been studied using structural, X-ray photoemission spectroscopy, magnetic and transport measurements. The La0.5Sr0.5Co1−xVxO3−δ (x = 0, 0.01, 0.02 and 0.1) series was prepared by conventional solid-state reaction method and its chemical homogeneity was established by inductively coupled plasma mass spectroscopy. The increase of lattice parameters/volume with increasing V5+ content in rhombohedrally crystallized (R 3 - c) samples is attributed to the presence of Co2+ ions . The presence of Co2+ ions and the reduction of Co3+ ion concentration with V substitution is verified from the results of core-level photoemission spectra of Co. Detailed magnetic measurements show an increase in Curie temperature, effective magnetic moment, soft magnetic nature and suggesting strengthening of underlying magnetic interactions. As a result of multiple oxidation states of Co ions and the delocalization of electrons, rise in the conductivity is noticed. Such enhancement in the conductivity and ferromagnetic ordering temperature, simultaneously, with V doping implies a strong coupling between spin and charge degrees of freedom. To understand the underlying mechanism more clearly, different possible scenarios have been discussed. The most appropriate scenario i.e., the conversion of Co3+ ions into Co2+ ions and admixture of Co4+ ion spin states with V5+ doping was found to be consistent with all the experimental observations.

Tuning of superconducting phase transition temperature (Ts) and interfacial magnetism is of great technological importance for micro and nanoelectronics. To achieve the cherished goal, an ultra-thin layer (4 nm, 6 nm, 8 nm 10 nm) of ferroelectrics PbZr0.48Ti0.52O3 (PZT) on high-temperature superconductor YBa2Cu3O7-δ (YBCO) has deposited to tailor the magnetic and superconducting properties. The existence of Meissner effect confirmed the superconducting nature of YBCO in the heterostructures. However, its Ts significantly shifted to the lower temperature side with an increase in PZT capping layers' thickness. Nearly 10 K reduction in Ts was observed with an increase in the capping layer from 4 to 10 nm. A significant amount of magnetic moment was found in the heterostructures, which increases almost three times compared to the YBCO/LAO magnetic moment above Ts. We believe novel weak magnetic phases above the Ts may be due to the re-arrangement of oxygen anion near the ferroelectric-superconducting interface.

The present study reports on the structural and magnetic phase transitions in Pr-doped polycrystalline Tb0.6Pr0.4MnO3, using high-resolution neutron powder diffraction (NPD) collected at SINQ spallation source, to emphasize the suppression of the sinusoidal magnetic structure of pure TbMnO3 and the evolution to a collinear A-type antiferromagnetic ordering. The phase purity, Jahn–Teller distortion, and one-electron bandwidth for eg orbital of Mn3+ cation have been calculated for polycrystalline Tb0.6Pr0.4MnO3, in comparison to the parent materials TbMnO3 and PrMnO3, through the Rietveld refinement study from x-ray diffraction data at room temperature, which reveals the GdFeO3 type orthorhombic structure of Tb0.6Pr0.4MnO3 having Pnma space group symmetry. The temperature-dependent zero field-cooled and field-cooled dc magnetization study at low temperature down to 5 K reveals a variation in the magnetic phase transition due to the effect of Pr3+ substitution at the Tb3+ site, which gives the signature of the antiferromagnetic nature of the sample, with a weak ferromagnetic component at low temperature-induced by an external magnetic field. The field-dependent magnetization study at low temperatures gives the weak coercivity having the order of 2 kOe, which is expected due to the canted-spin arrangement or ferromagnetic nature of Terbium ordering. The NPD data for Tb0.6Pr0.4MnO3 confirms that the nuclear structure of the synthesized sample maintains its orthorhombic symmetry down to 1.5 K. Also, the magnetic structures have been solved at 50 K, 25 K, and 1.5 K through the NPD study, which shows an A-type antiferromagnetic spin arrangement having the magnetic space group Pn′ma′.

In the present paper, the gallium modified lead zirconate titanate ceramics with Zr/Ti = 48/52 (near the morphotropic phase boundary,MPB), having a chemical formula Pb0.98Ga0.02(Zr0.48Ti0.52)0.995O3, was synthesized by a mixed-oxide reaction method and sintered. Analysis of phase formation confirmed the co-existence of two phases (tetragonal and monoclinic symmetry) in the system. Microstructural study by scanning electron microscope showed a non-uniform distribution of large grains over the sample surface and presence of a small amount of micro-size pores. Modulus and impedance studies were carried out at various frequencies (1 kHz-1MHz) and temperatures (300-350?C) and showed the contributions of grains in capacitive and resistive properties of the material. The resistance and capacitance of the complex impedance plots are contributed by grains as observed from the Nyquist plots. The experimental data obtained from the Nyquist plot were implemented in an equivalent electrical circuit (RQC). The value of grain resistance and capacitance were obtained using fitting steps with precision at all temperatures. It is assumed that increase of dielectric constant at higher temperatures is due to the substitution of Ga+ ions at the Pb-site.

This is the novel report on the rapid synthesis of single phase BiFeO3 nanorods by novel hot wall assisted spray pyrolysis system. The deposition has been carried out in an indigenously fabricated system and the entire process is completed in 4 s time duration. The structural, morphological, optical and magnetic properties of BiFeO3 nanorods have been studied in the work. The mechanism of growth of BiFeO3 nanorods has been explained extensively. The magnetic studies carried out with SQUID-VSM results BiFeO3 nanorods showing higher saturated magnetization in comparing with previous reports.

In view of their immensely intriguing properties, two-dimensional (2D) materials are being intensely researched in search of novel phenomena and diverse application interests; however, studies on the realization of 2D/2D nanocomposites in the application-worthy thin-film platform are rare. Here we have grown $\mathrm{Mo}{\mathrm{S}}_{2}$-hexagonal boron nitride (hBN) 2D/2D composite thin films on different substrates by the pulsed laser deposition technique and made comparative studies with the pristine $\mathrm{Mo}{\mathrm{S}}_{2}$ and hBN films. The Raman and x-ray photoelectron spectroscopy techniques as well as high-resolution transmission electron microscopy confirm the concomitant presence of both the 1T (conducting) and 2H (semiconducting) polymorphs of $\mathrm{Mo}{\mathrm{S}}_{2}$ in the composite film. Interestingly, a peculiar reentrant semiconductor-metal-insulator transition is seen in the $\mathrm{Mo}{\mathrm{S}}_{2}\ensuremath{-}\mathrm{hBN}$ 2D/2D composite film which is absent in the $\mathrm{Mo}{\mathrm{S}}_{2}$ film, and it correlates well with the signatures of phonon softening seen in temperature-dependent Raman spectroscopy. Furthermore, electrostatic force microscopy reveals the presence of three distinct regions (metallic, semiconducting, and insulating) in the $\mathrm{Mo}{\mathrm{S}}_{2}\ensuremath{-}\mathrm{hBN}$ composite film with differing contact potentials and enhanced propensity for charge transfer with respect to pristine $\mathrm{Mo}{\mathrm{S}}_{2}$. A triboelectric nanogenerator device containing biphasic $\mathrm{Mo}{\mathrm{S}}_{2}\ensuremath{-}\mathrm{hBN}$ composite film as an electron acceptor exhibits more than twofold (sixfold) enhancement in peak-to-peak output voltage as compared to the pristine $\mathrm{Mo}{\mathrm{S}}_{2}$ (hBN) film. These observations bring out the potential of 2D/2D nanocomposite thin films for unfolding emergent phenomena and technological applications.

ZnO thin films find widespread applications in optoelectronic devices, such as LEDs, UV photodetectors, etc. ZnO is an n-type semiconductor and diffusion of As in ZnO leads to p-type conductivity of ZnO. We report here application of combined x-ray reflectivity (XRR) and grazing incidence x-ray fluorescence (GIXRF) technique for the study of diffusion of As in the ZnO thin film structure, deposited on top of GaAs substrate, with accuracies better than 1 nm. Unlike conventional analysis probes, secondary ion mass spectrometry (SIMS) and depth resolved X-ray photoelectron spectroscopy (XPS), the present method allows element specific analysis of the thin film medium in a non-destructive manner.

The polycrystalline double perovskite-La2CoNiO6 ceramics were successfully synthesised by facile wet chemical route. The X-ray diffraction pattern has confirmed the formation of rhombohedral phase with R3c symmetry and calculated value of lattice parameters as, a = b = 5.64 A and c =13.25 A, respectively. The presence of La3+ ions, Co2+/Co3+ ions, and Ni2+ ions on the surface of La2CoNiO6 has been exhibited via X-ray photoelectron spectroscopy. The temperature and frequency dependent dielectric and impedance analysis has revealed the effect of grains and grain boundaries in the relaxation process. The observed values of ac conductivity varied from 5.27 × 10−6 S/m to 1.06 × 10−5 S/m with variation of temperature from 300 K to 473 K at frequency of 1 kHz. Further, La2CoNiO6 is a new ferromagnetic semiconductor exhibiting spin glass transition at low temperature of ~50 K. The present first report on structural, dielectric and magnetic study makes La2CoNiO6 a promising material for electronic devices applications.

Realization of oxide/oxide semiconductor heterostructures based high performance electronic/optoelectronic/magneto-optical devices warrants in-depth understanding of energy band alignment at their interface. Herein, we report energy band alignment in pulsed laser ablated Cr2O3/Ti0.02Cr1.98O3 bilayer film from the knowledge of core level energies and valence band maxima positions in the corresponding Cr2O3 and Ti0.02Cr1.98O3 single layer films and their respective shifts in Cr2O3/Ti0.02Cr1.98O3 bilayer film. A type II (staggered) band alignment was identified, with the valence band offset and conduction band offset equals to 1.40 eV and 1.13 eV, respectively. This investigation will provide further insights into the fundamental properties of Cr2O3/Ti0.02Cr1.98O3 heterojunction, which can be effectively utilized for the design, modelling and analysis of optoelectronic/magneto-optical devices.

We have investigated the structural and magnetic phase transitions in Sr doped polycrystalline Tb0.55Sr0.45MnO3, using temperature-dependent high-resolution neutron powder diffraction in the HRPT diffractometer at PSI to address the origin of magnetization reversal at low temperature. The solid solution Tb0.55Sr0.45MnO3 crystallizes in O′ type orthorhombic structure having the Pnma symmetry. The substitution of the divalent cation of Sr2+ at the site of Tb3+ dilutes the Mn–Tb interaction and affects the magnetic structure, which was observed by the field and temperature-dependent dc magnetization and neutron diffraction study. The temperature-dependent zero field-cooled and field cooled dc magnetization study reveals the indication of spin reversal phenomena, which is the nature of canted antiferromagnetic or ferrimagnetic transition at 100 Oe because of Mn–Mn sub-lattices interaction below 65 K. By increasing the applied magnetic field up to 20 kOe, a weak ferromagnetic type of behaviour is observed. The field-dependent magnetization shows weak coercivity due to the canted spin structure at low temperatures. The low-temperature neutron diffraction study of polycrystalline Tb0.55Sr0.45MnO3 reveals the non-collinear canted antiferromagnetic structure due to Tb ordering at 1.5 K, which turns into a non-collinear ferromagnetic structure along with spin canting followed by the spin reversal phenomena at 25 K.