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Our purpose was to evaluate the maximum tolerated dose of hypofractionated proton beam radiation therapy with concurrent weekly carboplatin/paclitaxel in patients with stage II-III non-small cell lung cancer.A phase I trial was designed using the time-to-event continuous reassessment method. Maximum tolerated dose was defined as the dose associated with a 20% probability of Common Terminology Criteria for Adverse Events protocol-specified serious adverse events (SAEs). Starting dose was 3.5 Gy/fx for 15 fractions with 2 potential escalation and de-escalation levels in 0.25 Gy/fx increments. Chemotherapy was weekly concurrent carboplatin/paclitaxel with 2 cycles of optional consolidation carboplatin/paclitaxel.From May 2015 to September 2016, 23 patients enrolled at a single institution. Of 20 evaluable, median age was 66.5 years (range, 54-89) and 12 were male (60%). Fourteen (70%) had squamous cell and 15 (75%) were stage IIIA. Nineteen (95%) completed all 3 cycles of concurrent chemotherapy, and 16 (80%) received at least 1 cycle of consolidation chemotherapy. Within the 6-month time-to-event continuous reassessment method assessment window, no SAEs were reported, and most patients were treated at the highest dose level. Dose level assignment was 52.5 Gy (n = 2), 56.25 Gy (n = 4), and 60 Gy (n = 14). The posterior probability of dose-limiting toxicity for 60 Gy was 5.3% (95% confidence interval, 1%-18.1%). Acute, nonserious AEs included grade 2 esophagitis in 7 patients (35%) and grade 2 pneumonitis in 1 patient (5%). At a median follow-up of 20.3 months for all and 44.9 months for living patients, there were no grade 4 or 5 AEs, though there were 3 (21% at 24 months) SAEs outside of the dose-escalation window. The 2-year overall survival, local, regional, and distant control rates were 48%, 84%, 77%, and 79%, respectively.Hypofractionated proton beam radiation therapy and chemotherapy up to 60 Gy in 15 fractions is acutely well tolerated, with high rates of locoregional control and overall survival, though late SAEs were noted.

A kV imager coupled to a novel, ring-gantry radiotherapy system offers improved on-board kV-cone-beam computed tomography (CBCT) acquisition time (17-40 seconds) and image quality, which may improve CT radiotherapy image-guidance and enable online adaptive radiotherapy. We evaluated whether inter-observer contour variability over various anatomic structures was non-inferior using a novel ring gantry kV-CBCT (RG-CBCT) imager as compared to diagnostic-quality simulation CT (simCT).Seven patients undergoing radiotherapy were imaged with the RG-CBCT system at breath hold (BH) and/or free breathing (FB) for various disease sites on a prospective imaging study. Anatomy was independently contoured by seven radiation oncologists on: 1. SimCT 2. Standard C-arm kV-CBCT (CA-CBCT), and 3. Novel RG-CBCT at FB and BH. Inter-observer contour variability was evaluated by computing simultaneous truth and performance level estimation (STAPLE) consensus contours, then computing average symmetric surface distance (ASSD) and Dice similarity coefficient (DSC) between individual raters and consensus contours for comparison across image types.Across 7 patients, 18 organs-at-risk (OARs) were evaluated on 27 image sets. Both BH and FB RG-CBCT were non-inferior to simCT for inter-observer delineation variability across all OARs and patients by ASSD analysis (p 0.001), whereas CA-CBCT was not (p = 0.923). RG-CBCT (FB and BH) also remained non-inferior for abdomen and breast subsites compared to simCT on ASSD analysis (p 0.025). On DSC comparison, neither RG-CBCT nor CA-CBCT were non-inferior to simCT for all sites (p 0.025).Inter-observer ability to delineate OARs using novel RG-CBCT images was non-inferior to simCT by the ASSD criterion but not DSC criterion.

The Bi–Al doped M-type hexaferrite (BaFe11.8Bi0.1Al0.1O19) was prepared by the use of sol gel auto combustion process. The prepared sample was sintered at 1000 °C for 5 h. Polyaniline was synthesized by oxidative polymerization. Mechanical blending was used to synthesize BaFe11.8Bi0.1Al0.1O19-PANI composite. X-ray diffraction (XRD), Fourier Transform Infra-red spectroscopy (FTIR), Field Emission Scanning Electron Microscope, Energy Dispersive X-ray spectroscopy and UV–vis-NIR spectroscopy were used for structural and optical analysis. XRD spectra show pure single phase of M-type hexagonal ferrites. The presence of bands in FTIR spectra in the range of 400–600 cm−1 and 800–1600 cm−1 indicate possible formation of hexaferrite and PANI. The band gaps were found nearly 2.24, 2.36 and 2.21 eV for HP1, HP2 and HP3 respectively.

Summary Background A systematic understanding of population-level trends in deaths due to road injuries at the subnational level over time for India's 1·4 billion people, by age, sex, and type of road user is not readily available; we aimed to fill this knowledge gap. Methods As part of the Global Burden of Diseases, Injuries, and Risk Factors Study, we estimated the rate of deaths due to road injuries in each state of India from 1990 to 2017 based on several verbal autopsy data sources. We calculated the number of deaths and death rate for road injuries by type of road user, and assessed the age and sex distribution of these deaths over time. Based on the trends of the age-standardised death rate from 1990 to 2017, we projected the age-standardised death rate to 2030 to assess if the states of India would meet the Sustainable Development Goal (SDG) target to halve the death rate for road injuries from 2015 by 2020 or 2030. We calculated 95% uncertainty intervals (UIs) for the point estimates. Findings In 2017, 218 876 deaths (95% UI 201 734 to 231 141) due to road injuries occurred in India, with an age-standardised death rate for road injuries of 17·2 deaths (15·7 to 18·1) per 100 000 population, which was much higher in males (25·7 deaths [23·5 to 27·4] per 100 000) than in females (8·5 deaths [7·2 to 9·1] per 100 000). The number of deaths due to road injuries in India increased by 58·7% (43·6 to 74·7) from 1990 to 2017, but the age-standardised death rate decreased slightly, by 9·2% (0·6 to 18·3). In 2017, pedestrians accounted for 76 729 (35·1%) of all deaths due to road injuries, motorcyclists accounted for 67 524 (30·9%), motor vehicle occupants accounted for 57 802 (26·4%), and cyclists accounted for 15 324 (7·0%). India had a higher age-standardised death rate for road injury among motorcyclists (4·9 deaths [3·9–5·4] per 100 000 population) and cyclists (1·2 deaths [0·9–1·4] per 100 000 population) than the global average. Road injury was the leading cause of death in males aged 15 to 39 years in India in 2017, and the second leading cause in this age group for both sexes combined. The overall age-standardised death rate for road injuries varied by up to 2·6 times between states in 2017. Wide variations were seen between the states in the percentage change in age-standardised death rate for road injuries from 1990 to 2017, ranging from a reduction of 38·2% (22·3 to 51·7) in Delhi to an increase of 17·0% (0·6 to 34·7) in Odisha. If the trends estimated up to 2017 were to continue, no state in India or India overall would achieve the SDG 2020 target in 2020 or even in 2030. Interpretation India's contribution to the global number of deaths due to road injuries is increasing, and the country is unlikely to meet the SDG targets if the trends up to 2017 continue. India needs to implement evidence-based road safety interventions, promote strong policies and traffic law enforcement, have better road and vehicle design, and improve care for road injuries at the state level to meet the SDG goal. Funding Bill & Melinda Gates Foundation and Indian Council of Medical Research, Department of Health Research, Ministry of Health and Family Welfare, Government of India.

In this manuscript, we demonstrate a method based on atomic force microscopy which enables local probing of surface wettability. The maximum pull-off force, obtained from force spectroscopy shows a remarkable correlation with the macroscopically observed water contact angle, measured over a wide variety of surfaces starting from hydrophilic, all the way through to hydrophobic ones. This relationship, consequently, facilitates the establishment of a universal behaviour. The adhesion forces scale with the polar component of surface energy. However, no such relation could be established with the dispersive component. Hence, we postulate that the force(s) which enable us to correlate the force spectroscopy data measured on the nanoscale to the macroscopic contact angle are primarily arising from electrostatic-dipole-dipole interactions at the solid-liquid interface. London forces play less of a role. This effect in is line with density functional theory (DFT) calculations suggesting a higher degree of hydroxylation of hydrophilic surfaces. This result shows that molecular simulations and measurements on an atomic scale can be extrapolated to macroscopic surface wetting problems.

Mg-doped zinc oxide (Zn1-xMgxO) (02 gas molecules and moisture present in the atmosphere. The formation of ZnO with no traces of Mg effect visible shift in XRD peak suggests the sample preparation process does not allow enough time to form a nanocomposite of Zn1-xMgxO.

The Einstein coefficients and radiative lifetimes for diatomic molecules such as N-2 and CO have been computed using the Fourier Grid Hamiltonian (FGH) method and a comparison with other methods has been made. The Hamiltonian matrix is constructed using the Hulburt and Hirschfelder (HH) potential model and the Rydberg-Klein-Rees (RKR) potential model for diatomic molecules. The FGH method works well for any model of the potential including the tabulated forms of experimental potential energy data. The eigenvalues and vibrational wave-functions for the ground and the exited state of N-2 and CO molecules have been computed by diagonalizing the Hamiltonian matrix. The vibrational wave-functions and eigenvalues for the ground and the excited states are used to calculate the radiative transition parameters such as Einstein coefficients (A(v '' v')), radiative lifetimes, electronic transition dipole moments (R-e(x)), Franck-Condon factors (FCFs), r-Centroids and average internuclear separations for both the models. FGH method work well for both the models. There are good agreements between our computed values of radiative transition parameters for both the models and the values estimated by other methods. (C) 2015 Elsevier B.V. All rights reserved.

Ultrafast optical studies have been performed on epitaxial films of the novel B-phase of vanadium dioxide using temperature-dependent optical pump-probe technique. Signature of temperature-driven metal-to-insulator transition was distinctly observed in the ultrafast dynamics — the insulating phase showed two characteristic electronic relaxation times while the metallic phase showed only one. Beyond a threshold value of the pump fluence, the insulating state collapses into a ‘metallic-like’ phase which can be further subdivided into two regimes according to the lengths of the fast characteristic time. The first regime can be explained by lattice heating due to the optical pump; the other cannot be accounted by simple lattice heating effects alone, and thus offers evidence for a true photoinduced phase transition. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Published version

Complexes of MM′(SeCN)4, (M = Co2+, Ni2+; M′ = Cd2+, Zn2+) with the Schiff base, N,N′-bis(2-chlorobenzylidene)ethylenediamine have been synthesized and characterized by elemental analysis, molar conductance, magnetic moment, FTIR, 1H-NMR, 13C{1H}-NMR and electronic spectroscopy. The catalytic activity of these complexes for hydrolysis of benzonitrile has been investigated. The complexes have also been investigated for antibacterial activity against Escherichia Coli and found to exhibit good growth inhibiton.

Metamaterials open up various exotic means to control electromagnetic waves and among them polarization manipulations with metamaterials have attracted intense attention. As of today, static responses of resonators in metamaterials lead to a narrow-band and single-function operation. Extension of the working frequency relies on multilayer metamaterials or different unit cells, which hinder the development of ultra-compact optical systems. In this work, we demonstrate a switchable ultrathin terahertz quarter-wave plate by hybridizing a phase change material, vanadium dioxide (VO2), with a metasurface. Before the phase transition, VO2 behaves as a semiconductor and the metasurface operates as a quarter-wave plate at 0.468 THz. After the transition to metal phase, the quarter-wave plate operates at 0.502 THz. At the corresponding operating frequencies, the metasurface converts a linearly polarized light into a circularly polarized light. This work reveals the feasibility to realize tunable/active and extremely low-profile polarization manipulation devices in the terahertz regime through the incorporation of such phase-change metasurfaces, enabling novel applications of ultrathin terahertz meta-devices.

A remarkable feature of vanadium dioxide is that it can be synthesized in a number of polymorphs. The conductivity mechanism in the metastable layered polymorph VO2(B) thin films has been investigated by terahertz time-domain spectroscopy (THz-TDS). In VO2(B), a critical temperature of 240 K marks the appearance of a non-zero Drude term in the observed complex conductivity, indicating the evolution from a pure insulating state towards a metallic state. In contrast, the THz conductivity of the well-known VO2(M1) is well fitted only by a modification of the Drude model to include backscattering. We also identified two different THz conductivity regimes separated by temperature in these two polymorphs. The electronic phase diagram is constructed, revealing that the width and onset of the metal-insulator transition in the B phase develop differently from the M1 phase.

Vanadium dioxide $({\mathrm{VO}}_{2})$ undergoes an unusual insulator-metal transition (IMT), and after decades of study, the origin of the IMT remains hotly debated. Here, by analyzing spectral-weight transfers (SWTs) of x-ray absorption spectroscopy at the $\mathrm{V}\phantom{\rule{0.28em}{0ex}}{L}_{3,2}$ and O K edges on specially designed ${\mathrm{VO}}_{2}$ films, we observe ${d}_{||}\phantom{\rule{0.28em}{0ex}}({d}_{{x}^{2}\ensuremath{-}{y}^{2}})$ band splitting at the $\mathrm{V}\phantom{\rule{0.28em}{0ex}}{L}_{3,2}$ edges across the IMT, accompanied by anomalous SWTs as high as $\ensuremath{\sim}12\phantom{\rule{0.28em}{0ex}}\mathrm{eV}$ at the $\mathrm{O}\phantom{\rule{0.28em}{0ex}}K$ edge, indicating strong electronic correlations. Surprisingly, a few oxygen vacancies induce dramatic SWTs at the $\mathrm{O}\phantom{\rule{0.28em}{0ex}}K$ edge, but the sample remains conducting. Supported by theoretical calculations, we find that in the metallic state, direct $\mathrm{V}(3{d}_{\ensuremath{\parallel}})\text{-V}(3{d}_{\ensuremath{\parallel}})$ and $\text{O}(2p)\text{-V}(3{d}_{\ensuremath{\parallel}})$ hybridized orbital correlations are screened by $\text{O}(2p)\text{-V}(3{d}_{\ensuremath{\pi}})$ hybridized orbitals, while in the insulating state they are strongly correlated due to changes in the oxygen orbital occupancy. Our result shows the importance of screenings and electronic correlations for IMTs in ${\mathrm{VO}}_{2}$.

Ta and Nb substituted TiO2 are important transparent conducting oxides that have potential for applications in photovoltaics, photocatalysis, and water splitting/CO2 sequestration. In addition to donating electrons, what are the effects of Nb and Ta substitution? Here we observe strong experimental evidence that Ta and Nb substitution induces large and small polarons in anatase TiO2 epitaxial thin films. The degenerate donor electrons (from both Nb and Ta) show a high temperature T3 dependence on electrical resistivity, which confirms the presence of large polarons, along with room temperature metallic transport. This is further confirmed by the enhancement in the electron effective mass, which was estimated from thermopower measurements. Femtosecond transient absorption (fs-TA) reveals the life time of the Ti-t2g and eg levels and the separation of these levels are consistent with the X-ray absorption spectroscopy (XAS) measurement. In addition, fs-TA reveals the presence of small polarons with a life time substantially >1 ns, which arises from defect levels and is a consequence of Ta and Nb substitution. X-ray photoelectron spectroscopy (XPS) provides evidence of Ti3+, which may be identified as the defects responsible for the small polarons. These long-lived small polarons may provide a way to minimize recombination dynamics in TiO2-based electrodes for photo-excited devices.

Reactions of five sym-diarylthioureas (L), viz,, sym-diphenylthiourea (dptu), sym-di-o-tolylthiourea (dottu), sym-di-p-tolylthiourea (dpttu), sym-di-o-anisylthiourea (doatu) and sym-di-α- naphthylthiourea (dαntu) with W(CO)6 have been performed both by reflux and ultra-violet irradiation methods in which only monosubstituted products [(L)W(CO)5] are obtained. Several mixed ligand tungsten carbonyl derivatives, viz., [(o-phen or 2,2’-bipy)(L)W(CO)3] and [(Ph3P or Ph3As)(L)W(CO)4] have also been synthesized. Halogenation of [(L)W(CO)5] yielded heptacoordinated [(L)W(CO)4X2] (X = Br or I). The complexes have been characterized by microanalytical data, conductivity and IR measurements. The C-O stretching force constants and CO-CO stretch-stretch interaction constants of [(L)W(CO)5] derivatives have also been evaluated from the IR spectra.

High-k dielectric oxides are supposedly ideal gate-materials for ultra-high doping in graphene and other 2D-crystals. Here, we report a temperature-dependent electronic transport study on chemical vapor deposited-graphene gated with SrTiO₃ (STO) thin film substrate. At carrier densities away from charge neutrality point the temperature-dependent resistivity of our graphene samples on both STO and SiO₂/Si substrates show metallic behavior with contributions from Coulomb scattering and flexural phonons attributable to the presence of characteristic quasi-periodic nano-ripple arrays. Significantly, for graphene samples on STO substrates we observe an anomalous 'slope-break' in the temperature-dependent resistivity for T = 50 to 100 K accompanied by a decrease in mobility above 30 K. Furthermore, we observe an unusual decrease in the gate-induced doping-rate at low temperatures, despite an increase in dielectric constant of the substrate. We believe that a complex mechanism is at play as a consequence of the structural phase transition of the underlying substrate showing an anomalous transport behavior in graphene on STO. The anomalies are discussed in the context of Coulomb as well as phonon scattering.

The confinement of the two-dimensional electron gas (2DEG), preferential occupancy of the Ti 3$d$ orbital, and strong spin-orbit coupling at the LaAlO${}_{3}$/SrTiO${}_{3}$ interface play a significant role in its emerging properties. Here we report a fourfold oscillation in the anisotropic magnetoresistance (AMR) and planar Hall effect (PHE) at the LaAlO${}_{3}$/SrTiO${}_{3}$ heterointerface. We evaluate the carrier confinement effects on the AMR and find that the fourfold oscillation appears only for the case of 2DEG systems while it is twofold for the three-dimensional system. The AMR behavior is further found to be sensitive to applied electric field, emphasizing the significance of spin-orbit coupling at the interface. These confinement effects suggest that the magnetic interactions are predominant at the interface, and the gate electric field modulation of AMR shows the tunability of magnetic interactions. As the fourfold oscillation fits well to the phenomenological model for a cubic symmetry system, this suggests that the origin of the oscillation may be linked to the anisotropy in magnetic scattering arising from the interaction of electrons with the localized magnetic moments coupled to the crystal symmetry. The observed large PHE further indicates the in-plane nature of magnetic ordering that arises from the in-plane Ti 3${d}_{xy}$ orbitals.

The observation of a high-mobility two-dimensional electron gas between two insulating complex oxides, especially LaAlO3/SrTiO3, has enhanced the potential of oxides for electronics. The occurrence of this conductivity is believed to be driven by polarization discontinuity, leading to an electronic reconstruction. In this scenario, the crystal orientation has an important role and no conductivity would be expected, for example, for the interface between LaAlO3 and (110)-oriented SrTiO3, which should not have a polarization discontinuity. Here we report the observation of unexpected conductivity at the LaAlO3/SrTiO3 interface prepared on (110)-oriented SrTiO3, with a LaAlO3-layer thickness-dependent metal-insulator transition. Density functional theory calculation reveals that electronic reconstruction, and thus conductivity, is still possible at this (110) interface by considering the energetically favourable (110) interface structure, that is, buckled TiO2/LaO, in which the polarization discontinuity is still present. The conductivity was further found to be strongly anisotropic along the different crystallographic directions with potential for anisotropic superconductivity and magnetism, leading to possible new physics and applications., Although LaAlO3 and SrTiO3 are both insulators, when they are brought together at a (100) interface, a highly conducting two-dimensional electron gas forms between them. Annandi et al. show that this also happens at a (110) interface, counter to expectations that it should not.

We report evolution of the two-dimensional electron gas behavior at the NdAlO3/SrTiO3 heterointerfaces with varying thicknesses of the NdAlO3 overlayer. The samples with a thicker NdAlO3 show strong localizations at low temperatures and the degree of localization is found to increase with the NdAlO3 thickness. The T -1/3 temperature dependence of the sheet resistance at low temperatures and the magnetoresistance study reveal that the conduction is governed by a two-dimensional variable range hopping mechanism in this strong localized regime. We attribute this thickness dependence of the transport properties of the NdAlO3/SrTiO3 interfaces to the interface strain induced by the overlayers., Comment: 15 pages, 4 figures

Aldimines (Ald) such asN,N′-bis(4-methylbenzylidene)1,2-propanediamine (Ald1),N,N′-bis(4-methoxybenzylidene)-1,2-propanediamine (Ald2) orN,N′-bis(4-N,N-dimethylaminobenzylidene)-1,2- propanediamine (Ald3) reacted with Mo(CO)6 to give the respectivecis-[(Ald)Mo(CO)4] complexes.N,N′-bis-(4-N,N′-dimethylaminobenzylidene)-1,3-propanediamine, in spite of comparatively poor reactivity, gave analogous tetracarbonyl, but its 1,4-butanediamine and 1,6-hexanediamine analogues did not give similar derivatives. Ald1-Ald3 after reaction with [(Ph3P)Mo(CO)5] gave corresponding aldimine bridged dinuclear [(Ph3P)(CO)4Mo(μ-Ald)Mo(CO)4(Ph3P)].Cis-[(Ald)Mo(CO)4] gave [(Ald)Mo(CO)3X2] when reacted with X2 (X = Br or I), but produced [(Ald)MoCl4] after reaction with chlorine. NO reacted with tetracarbonyls to yield a mixture of unusual [(NO)(Ald)Mo(CO)2(NO2)] and [(NO)2(Ald)Mo(NO2)2], but NOCl yielded only [(Ald)Mo(CO)2(NO)Cl].

We report optical, electrical and magnetotransport properties of oxygen deficient ${\mathrm{SrTiO}}_{3}$ (${\mathrm{SrTiO}}_{3\ensuremath{-}x}$) thin films fabricated by pulsed laser deposition technique. The oxygen vacancies (${\mathrm{O}}_{\mathrm{vac}}$) in the thin film are expected to be uniform. By comparing its electrical properties to those of bulk ${\mathrm{SrTiO}}_{3\ensuremath{-}x}$, it was found that ${\mathrm{O}}_{\mathrm{vac}}$ in bulk ${\mathrm{SrTiO}}_{3\ensuremath{-}x}$ is far from uniform over the whole material. The metal-insulator transition (MIT) observed in the ${\mathrm{SrTiO}}_{3\ensuremath{-}x}$ film was found to be induced by the carrier freeze-out effect. The low temperature frozen state can be reexcited by Joule heating, electric and intriguingly magnetic field.

(η-CH 3 C 5 H 4 )Mn(CO) 3 reacts with RNH 2 (R = n-C 4 H 9 , sec-C 4 H 9 , n-C 5 H 11 , n-C 6 H 13 , cyclo-C 6 H 11 , n-C 7 H 15 , n-C 8 H 17 , n-C 9 H 19 or C 6 H 5 CH 2 ) to give corresponding sym -dialkylureas when a 1 : 2 molar mixture of the two reactants is irradiated with UV light for 100–250 h. The complexes (η-CH 3 C 5 H 4 Mn(CO) 2 (CONHR)(H) were isolated for R = n-C 4 H 9 , n-C 6 H 13 and cyclo-C 6 H 11 .

Manipulating spin-orbit coupling (SOC) is important for devices such as spin-orbit torque based memory and its understanding is neccessary to answer several fundamental open questions in triplet state superconductivity, topological insulators and Majorana fermions. Here we report spin splitting of 25 meV at the LaAlO3/SrTiO3 (110) interface for in-plane spins at a current density of 1.4x104 A/cm2, which is large compared to that found in semiconductor heterostructures or the LaAlO3/SrTiO3 (100) interface, and in addition it is anisotropic. The anisotropy arises from the difference in electron effective mass along the [001] and [1-10] directions. Our study predicts a spin splitting energy > 1000 meV at a current density of 107 A/cm2, which is enormous compared to metallic systems and will be an ideal spin polarized source. In addition to the in-plane effect, there is an unexpected gate-tunable out-of-plane SOC at the LaAlO3/SrTiO3 (110) interface when the spins lie out-of-plane due to broken symmetry in the plane of the interface. We demonstrate that this can be manipulated by varying the LaAlO3 thickness showing that this interface can be engineered for spin-orbit torque devices., 17 pages, 5 figures in Advanced Electronic Materials (Wiley) Vol. 1, Issue 8, 2015

We demonstrate the growth of high quality single phase films of VO2(A, B, and M) on SrTiO3 substrate by controlling the vanadium arrival rate (laser frequency) and oxidation of the V atoms. A phase diagram has been developed (oxygen pres-sure versus laser frequency) for various phases of VO2 and their electronic properties are investigated. VO2(A) phase is insulating VO2(B) phase is semi-metallic, and VO2(M) phase exhibits a metal-insulator transition, corroborated by photo-electron spectroscopic studies. The ability to control the growth of various polymorphs opens up the possibility for novel (hetero)structures promising new device functionalities.

Here, we present the results of temperature dependent dielectric studies on chemical solution processed Zr-doped BiFeO3 (BFO) thin films deposited on Pt/Si substrates. We find that in contrast to the undoped BFO films, Zr doping at Fe-site suppresses the low frequency dielectric relaxation originating from the grain boundaries, attributed to the increased dipolar rigidity due to stronger Zr-O bonds. Temperature dependent dc conductivity obtained from impedance and modulus analyses shows two distinct conduction processes occurring inside the grains. At temperature below ∼ 423 K, conductivity is nearly temperature independent, while in the high temperature regime (above ∼ 423 K), conduction is governed by the long range movement of oxygen vacancies with an activation energy of ∼1 eV.

We have investigated the photoluminescence and electrical properties of a coherently coupled interface consisting of a ZnO layer grown on top of an oriented VO2 layer on sapphire across the phase transition of VO2. The band edge and defect luminescence of the ZnO overlayer exhibit hysteresis in opposite directions induced by the phase transition of VO2. Concomitantly the phase transition of VO2 was seen to induce defects in the ZnO layer. Such coherently coupled interfaces could be of use in characterizing the stability of a variety of interfaces in situ and also for novel device application.

In this paper, we report on the results of temperature dependent impedance measurements on chemical solution deposited BiFeO3 thin films on Pt/Si substrates. X-ray diffraction analysis showed the presence of predominately single phase BiFeO3. The measurements were made in the frequency range of 100–107 Hz and between 27 and 250 °C. Plots between real and imaginary parts of impedance (Z′ and Z″) and electrical modulus (M′ and M″) in the above frequency and temperature domain suggest the presence of two relaxation regimes which are attributed to bulk and grain boundary responses. Below 150 °C, both conductivity and real dielectric constant show a steplike behavior. The frequency independent regions in 10–100 kHz indicate relaxation of the bulk conduction, while at lower frequency there is a strong frequency dependence associated with the dispersion toward relaxation of the grain boundary. In contrast, at and above 150 °C, frequency independent behavior of dc conduction becomes dominant. The bulk dielectric ...