In this work, we present a systematic and detailed study on synthesis and characterization of near morphotropic phase boundary (MPB) composition, 0.65PMN–0.35PT {0.65Pb(Mg 1/3 Nb 2/3 )O 3 –0.35PbTiO 3 } ceramics prepared by columbite method. Phase purity and crystal structure of the prepared ceramics were studied using X-ray diffraction. Single-phase PMN-PT ceramics were subject to structural, dielectric, ferroelectric, piezoelectric, and electromechanical characterizations. Phase analysis using Rietveld refinement of XRD pattern of these ceramics revealed presence of rhombohedral and tetragonal phases of PMN–PT confirming composition to near MPB. A highly dense microstructure was observed from field emission gun-scanning electron microscopy (FEG–SEM) with a relatively smaller grain size at a comparatively lower sintering temperature. Dielectric measurements indicated a broad diffused phase transition. Ferroelectric studies revealed a square loop hysteresis at room temperature with relatively large coercivity. A strong piezoelectric behavior was observed by strain versus electric filed measurement at 1 Hz. A comparison of the observed values of various parameters with existing literature on these ceramics has been made to establish exclusivity of our results.

In this work, we have investigated the resistive switching (RS) properties of metal-insulator-metal (MIM) RRAM (resistive random-access memory) devices based on Hafnium Oxide (HfO2) films. A systematic study on the effect of substrate temperature on the crystallinity and its correlation with RS behaviour of HfO2 films deposited on platinized silicon using the Pulsed Laser Deposition (PLD) has been performed. Grazing-incidence X-ray diffraction and X-ray reflectivity techniques were employed to analyse the phase formation and the thickness of the films, respectively. The films were deposited at two different substrate temperatures 400 °C and 700 °C. A lower substrate temperature led to an amorphous film while the higher substrate temperature resulted in a polycrystalline film. The effect of change in amorphous to polycrystalline nature of HfO2 films with substrate temperature was studied on RS behaviour of these films. To assess the RS behaviour, DC electrical characterization was conducted on stacked W/HfO2/Pt thin films. The electrical characterization revealed forming-free bipolar RS behavior in both the films along with a digital SET and gradual RESET. The resistance of the films was found to be dependent on phase and microstructure which in turn depends upon substrate temperature. This study would be useful for the optimization of RS behaviour by tuning the crystallinity of the HfO2 films through processing temperature.

This work presents resistive switching (RS) behaviour in HfO2-based low-power resistive random-access memory (RRAM) devices. A metal-insulator-metal (MIM) structure (Au/HfO2/Pt) was fabricated by sandwiching a thin insulating layer of HfO2 between Pt and Au electrodes. HfO2 films deposited by RF sputtering at room temperature were rapid thermally annealed in N-2 ambient at 400 degrees C and 500 degrees C. Grazing angle x-ray diffraction (GIXRD), Field emission gun-scanning electron microscopy (FEG-SEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS) were employed to analyse the phase, crystal structure, morphology, surface roughness and chemical composition of the HfO2 films. The bipolar RS could be observed in both as-deposited and annealed HfO2 film-based devices from I-V characteristics measured using a source meter. We have investigated the effect of annealing temperature and annealing ambient on the phase formation of HfO2 as well as the RS characteristics and compared with as-deposited film-based device. Annealed HfO2 film-based devices exhibited improved electrical characteristics, including stable and repeatable RS at significantly lower switching voltages (<1 V) which indicates low power consumption in these devices. The relatively lower processing temperature of the HfO2 films and that too in the films deposited by physical vapor deposition (PVD) technique-RF magnetron sputtering makes this study significantly useful for resistive switching based non-volatile memories.

Electrical energy generation from renewable resources has been a quest in the last few decades to meet the energy demand of electrical appliances and gadgets. More importantly, portable gadgets and devices, wireless sensors, etc., which rely on batteries require intermittent charging, and it is difficult to find an omnipresent continuous electrical energy source connected to a power station for these batteries. Alternate to these power stations connected to electrical energy sources is harvesting the energy from omnipresent mechanical and acoustic vibrations and AC magnetic field. Energy harvesting from these waste energy resources is possible using piezoelectric and magnetoelectric materials. This chapter would discuss in detail various mechanisms and stimuli, which may be synergistically used to harvest energy from piezoelectric materials-based energy harvesters.

Transition metal-doped Zinc oxide (ZnO) thin films with an optimal wide band gap and semiconducting nature find numerous applications in optoelectronic devices, gas sensors, spintronic devices, and electronics. In this study, Zirconium (Zr) doped ZnO thin films were deposited on ITO (Indium Tin oxide) coated glass substrate using RF-magnetron sputtering. Optical and electrical properties were examined for their potential use in resistive random-access memory (RRAM) applications. X-ray Diffraction (XRD), UV-vis spectroscopy, x-ray photoelectron spectroscopy (XPS), Atomic force microscopy (AFM) and Scanning electron microscopy (SEM) were used to investigate structural, optical, and compositional properties and roughness respectively. The results demonstrate that the films possess crystalline properties. Additionally, an augmentation in Zr concentration correlates with an elevation in the optical band gap, ascending from 3.226 eV to 3.26 eV, accompanied by an increase in Urbach energy from 0.0826 eV to 0.1234 eV. The film with the highest Zr content among all the films demonstrated the best electrical performance for resistive memory applications. Incorporating Zr as a dopant shows enhancement in the electrical performance and such ZnO films with optimum concertation of Zr can potentially be used in RRAM. ZnO being a versatile host material, its doping with Zr may extend its applications in catalysis, gas sensing, energy storage, and biomedical engineering. ZnO thin films employ zirconium (Zr) as a dopant, which is a novel way to improve the material's characteristics. Although ZnO has been thoroughly researched, adding Zr presents a novel technique to enhance optical, electrical, and resistive memory characteristics all at once that has not been fully investigated.

Background:Post traumatic seizures (PTS) are a known sequel of traumatic brain injury (TBI). Incidence of PTS is dependent on many factors including study design and characteristics of the study population. As incidence of TBI increases and death due to TBI decreases, more individuals will be at risk of developing and living with chronic complications. The objective of the present study was to determine the frequency and risk factors for PTS following TBI.Methods:A prospective study was conducted on patients admitted with TBI from April 1, 2019, to May 31, 2020, to determine the frequency, time to event, and risk factors for PTS following TBI. We classified the severity of head injury using a standard criterion, into mild, moderate and severe injury. Follow-up of 3 months was undertaken for all patients. Variables include age, sex, trauma severity, Glasgow coma scale, onset of PTS, and neuroradiological finding.Results:We enrolled 450 post traumatic subjects, out of which 36 (8%) developed seizures. Of the total of 36 patients detected to have hemorrhagic contusion on computerized tomography scan, 12 patients developed seizures. We found that the independent risk factors associated with occurrence of PTS were frontal- temporal lobar contusion and severity of head injury. All these findings were statistically significant.Conclusion:We found that the independent risk factors associated with occurrence of PTS were frontal-temporal lobar contusion and severity of head injury. Type of management (Operative vs. Non operative) does not affect the outcome of PTS.

Lead based relaxor ferroelectrics with near morphotropic boundary composition (MPB) have been of tremendous research interest due to their exceptional properties. The synthesis of these materials in phase pure form involves complex process due to volatility of Lead oxide leading to less reproducibility of desired properties. Therefore, research on these materials has always been a field of inquisitiveness. Our work presents a systematic and detailed study on synthesis and characterization of near MPB composition 0.65PMN - 0.35PT ceramics by Columbite method. The prepared phase pure PMN-PT ceramics were subject to structural, electrical and electromechanical characterizations. Phase analysis of these ceramics revealed presence of rhombohedral and tetragonal phases of PMN-PT confirming composition to near MPB. However, ferroelectric and dielectric measurements indicated a composition away from MPB. We report the effect of purity of precursors, processing conditions and PT composition on the properties of these ceramics.

Resistive switching characteristics of ZnO‐based nanomaterials make them useful candidates for applications in resistive random access memory (RRAM). In the present work, Nb‐doped ZnO thin films prepared using RF sputtering with varying doping concentrations were studied using XRD, UV‐Vis spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X‐ray Spectroscopy (EDS), I‐V, XPS and AFM measurements to investigate the structural, optical, electrical properties and roughness of the films. The XRD analysis revealed a shift in the (002) peak corresponding to hexagonal wurtzite structure, towards lower angles with increasing doping concentration, indicating a doping‐induced modification of crystal structure. The UV‐Vis spectroscopy showed an increase in the band gap energy with increasing doping concentration. The electrical conductivity of the films was found to increase with doping concentration, as determined by I‐V measurements. The XPS analysis confirmed the presence of Nb in the doped films and provided information on the chemical states of the elements. Overall, the results suggest that Nb doping can significantly modify the structural properties of ZnO thin films which alters the electrical properties to match the requirements for potential applications in memory devices.

Transition metal doped Zinc oxide (ZnO) thin films with wide band gap semiconducting nature have diverse range of applications including, gas sensors, optical and optoelectronic devices, electronics and spintronics spintronic devices etc. In the present study, Manganese (Mn)-doped ZnO thin films deposited on glass substrates using RF-magnetron sputtering have been investigated for their optical and electrical behavior aiming at resistive random access memory applications. To study the influence of Mn doping and correlation between the structural and the physical properties of the films, the samples were characterized by X-ray Diffraction (XRD), Raman spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray Spectroscopy (EDS), UV-VIS spectrophotometry and X-ray photoelectron spectroscopy (XPS). The films are found to be crystalline and a decrease in lattice parameter from 2.6049 angstrom to 2.5845 angstrom, an increase in optical band gap from 3.27 eV to 3.35 eV and a decrease in Urbach energy from 0.222 eV to 0.171 eV, is observed with increase in Mn-concentration. The electrical performance of the film with highest Mn-content is found to be more suitable for resistive memory applications. Tailoring the electrical behavior of the film by incorporating Mn as dopant is an important approach to find suitable material combination for novel memory devices.

Background: Chronic subdural hematoma (CSDH) is seen most common in geriatric patients, and trauma is the most important reason for CSDH. Operative treatment of CSDH in symptomatic patients is yet the gold standard of therapy because it allows decompression of the subdural space and aids improvement in neurological status. Burr-hole craniostomy is the most common accepted treatment for CSDH. There is still controversy regarding which type of drain placement is best in the outcome: subdural or subgaleal drain. Aim: The aim of the study was to compare the outcome of subgaleal versus subdural drain in surgically treated patients of CSDH. Materials and Methods: Patients were assigned by simple random sampling in two groups. The study was conducted from February 2016 to July 2017. A total of 70 patients were enrolled into the study and were divided in two groups (Group 1 – Subgaleal drain; Group 2 – Subdural drain). Statistical analysis was done using Chi-square and t-test. Outcome was assessed at the end of hospital stay by modified Rankin scale. Postoperative computed tomography scan was done after 24 h of surgery. Results: This study concluded that both types of drains are equally effective for the treatment of CSDH. There is a statistically significant difference in the occurrence of seizure in both the groups as there was no seizure in subgaleal drain group compared to 5 (14.3%) patients who had seizures postoperatively in subdural drain group (P = 0.020). There was insignificant difference with respect to preoperative Glasgow Coma Scale/sex/preoperative hematoma volume/postoperative hematoma volume/preoperative midline shift. Conclusion: Subgaleal drain is safe and technically easy, as subgaleal drain has no direct contact with brain parenchyma, thus less chances of brain laceration, intracerebral hematoma formation, and seizures.

Background: Spontaneous intracranial haemorrhage (ICH) is the most severe type of stroke with high mortality rates. This entity accounts for 17 to 33% of all strokes and is associated with a higher mortality rate. Approximately, 35–50% of patients with ICH die within the 30 days after event. Long-term survivors are often remaining with permanent deficits, with up to 75% suffering permanent disability and only 12% to 39% of the survivors have favourable outcomes. Several studies aiming to explore the efficacy of surgery for patients with ICH have been carried out. However, the results were inconclusive. To provide evidence for clinical practice, here we present a retrospective study to explore the effect of surgery for patients with spontaneous basal ganglia haemorrhage. Methods: The present study was conducted in the Neurosurgery Department of a tertiary care hospital in the Northern part of India from January 2018 to March 2020. Sixty-one patients aged between 20-70 years of basal ganglia haemorrhage who presented within 24 hours of ictus and operated were included in this study. Results: A total of 61 patients underwent surgical intervention consisting of 49 (80%) males and 12 (20%) females. Their age varied from 27 to 70 with mean age ± SD 51.93 ± 13.19 years. Thirty-six patients were ≥ 50 years of age, out of which 72% patients had unfavourable outcomes (GOS 1-3) and 28% had favourable outcome (GOS 4-5). There were 31 patients with GCS 5-8. Most patients (81%) had GOS 1-3(at the time of discharge). Out of 25 patients with GCS 9-12; 64% had GOS 4-5. The patients with volume of haematoma 40-60 ml, 82% patients had GOS 4-5. The patients with midline shift > 5 mm; 78% patients had GOS 1-3. Patients with midline shift < 5 mm; 82% had GOS 4-5 (P=0.005). The mean hospital stays of unfavourable outcomes group was 28.71 ± 10.25 days and of favourable outcomes group was 22.07 ± 6.32 days (0.000). Conclusions: Early surgery (within 6 hours) along with multi-modality medical management has definite positive role in the outcome of patients with spontaneous basal ganglionic haemorrhage. Patients ≥ 50 years, signs of brain herniation, volume of haematoma ≥ 60ml, hydrocephalic dilatation due the intraventricular haemorrhage, midline shift > 5 mm, and GCS ≤ 8 at presentation had poor prognosis.

Lead based relaxor ferroelectric thin films can become very useful due to their excellent electrical properties, provided the growth difficulties and high cost of fabrication which have stymied their applications are overcome. Our work describes a systematic study of establishing a set of process conditions for reproducible depositions of 0.65Pb(Mg1/3Nb2/3)O-3-0.35PbTiO(3) (PMN-PT) thin films on La0.67Ca0.33MnO3 (LCMO) seeded Pt/TiO2/Glass substrates. Films were grown at ambient temperature using RF- magnetron sputtering. Single phase PMN-PT films could be obtained by ex situ thermal annealing in air for 2 h at temperatures of 550 and 650 degrees C. Films annealed at temperatures lower than 550 degrees C and films deposited without the LCMO buffer layer showed presence of pyrochlore phase. Effect of annealing temperature, on the microstructure, dielectric and ferroelectric properties of the PMN-PT films has been investigated. Scanning electron micrographs of single phase PMN-PT films show a bimodal grain size distribution for the thin films annealed at 550 and 650 degrees C. The films annealed at 650 degrees C yielded a dielectric constant of 1300 and a remnant polarization (2P(r)) of 17 mu C cm(-2).

The magneto-dielectric response in multiferroic ZnFe2O4/PMN-PT bilayer thin films prepared on a glass substrate using RF magnetron sputtering has been investigated in this work. PMN-PT thin films (i.e. PMN-PT/LCMO/Pt/Ti/glass) deposited on glass were used as a substrate for deposition of ZnFe2O4 thin films. ZnFe2O4 thin films were annealed ex situ at different temperatures. Structural, magnetic, ferroelectric, dielectric and magneto-dielectric studies were carried out on these multiferroic bilayer thin films. Structural studies revealed the presence of each layer in its respective single phase. Magnetic and ferroelectric studies revealed the ferromagnetic and ferroelectric behaviors of these bilayers. To quantify the magnetoelectric coupling, the dielectric constant of the bilayer was measured at room temperature as a function of frequency with and without the applied magnetic field. The magneto-dielectric response MD(%) was calculated by finding the relative change in dielectric constant at 1 kHz as a percentage. The observed MD response was correlated with magnetization of the ferrite layer. An MD response of 2.60% was found for a bilayer film annealed at 350 °C. At this particular annealing temperature, the ZnFe2O4 layer also has the highest saturation magnetization of 1900 G.

Lead based relaxor ferroelectric thin films have been of technological importance due to excellent properties for several commercial applications. However subtleness and high cost of fabrication have plagued of these materials. In this work a systematic study of PMN-PT thin films grown on LCMO buffered platinized glass substrates has been undertaken. The films were grown at room temperature using RF magnetron sputtering. Single phase PMN-PT films could be obtained by exsitu thermal annealing in air for 2h at temperatures 550 and 650 degree C. The films annealed at temperatures lower than 550 degree C and films without buffer layer showed presence of pyrochlore. Effect of annealing temperature on the microstructure, dielectric and ferroelectric properties of the PMN-PT films has been investigated. Scanning electron micrographs of single phase PMN-PT films show a bimodal grain size distribution for films annealed at 550 and 650 degree C. A high dielectric constant of 1300 and a remnant polarization (2Pr) of 17micro C/cm2 were observed for film annealed at 650 degree C.

Operational stability of organic devices at above-room-temperatures in ambient environment is of imminent practical importance. In this report, we have investigated the charge transport and degradation mechanisms in pentacene based organic field effect transistors (OFETs) operating in the temperatures ranging from 25°C to 150°C under ambient conditions. The thin film characterizations techniques (X-ray photoelectron spectroscopy, X-ray diffraction and atomic force microscopy) were used to establish the structural and chemical stability of pentacene thin films at temperatures up to 150°C in ambient conditions. The electrical behavior of OFETs varies differently in different temperature bracket. Mobility, at temperatures below 110°C, is found to be thermally activated in presence of traps and temperature independent in absence of traps. At temperatures above 110°C mobility degrades due to polymorphism in pentacene or interfacial properties. The degradation of mobility is compensated with the decrease in threshold voltage at high temperatures and OFETs are operational at temperatures as high as 190°C. 70°C has been identified as the optimum temperature of operation for our OFETs where both device behavior and material properties are stable enough to ensure sustainable performance.

In this work, RF- magnetron sputtering technique has been employed to deposit nanocrystalline ZnFe2O4 thin films at room temperature. The as grown films were ex-situ annealed in air for 2 h at temperatures from 150°C to 650°C. X-ray diffraction, vibrating sample magnetometer and ferromagnetic resonance were used to analyze the phase formation, magnetic properties and microwave properties respectively. From the hysteresis loops and ferromagnetic resonance spectra taken at room temperature, a systematic study on the effect of O2 plasma on microwave properties with respect to processing temperature has been carried out.

Synthesis of PMN-PT ceramics has been a challenge due to the undesirable pyrochlore phase formation. We have synthesized PMN-PT ceramics with varying PT content (x= 0.1, 0.15 and 0.3) using columbite precursor method. Influence of PT addition on the perovskite phase formation and microstructure has been studied using X-ray diffraction and scanning electron microscope respectively.

Synthesis of PMN-PT ceramics has been a challenge due to the undesirable pyrochlore phase formation. We have synthesized PMN-PT ceramics with varying PT content (x = 0.1, 0.15 and 0.3) using columbite precursor method. Influence of PT addition on the perovskite phase formation and microstructure has been studied using X-ray diffraction and scanning electron microscope respectively.

The observation and theory of a large remanent magnetoelectric (ME) coefficient and coercivity in the static field H dependence of the low-frequency ME effects are reported for bilayers of lead zirconate titanate (PZT) and a functionally graded ferromagnetic layer. The grading involves magnetization with the use of nickel zinc ferrite of composition Ni0.7Zn0.3Fe2O4 (NZFO) and pure Ni. In homogeneous bilayers of PZT-Ni or PZT-NZFO, the ME voltage coefficient (MEVC) vs H data do not show any hysteresis or remanence. Upon grading the ferromagnetic layer, significant changes including hysteresis and remanece are observed. In PZT-Ni-NZFO, MEVC vs H data show a positive remnant MEVC and a negative coercive field. When the grading is reversed, in samples of PZT-NZFO-Ni, the remnant MEVC is negative and the coercive field is positive. A theory is proposed for the low-frequency ME effects in the graded composites. According to the model, the grading in the magnetization leads to a built-in magnetic field in the ferromagnetic layer, and this field depends on the sequence of grading and the thickness of the NZFO and Ni layers. As a result, the total torque moment and flexural deformations in the composite and the bias field dependence of ME voltage coefficient becomes strongly hysteretic. Calculated MEVC vs H, remnant MEVC, and coercive field are in good agreement with the data.

Tin oxide (SnO2) thin films are of great interest in optoelectronics industries due to their promising properties such as conductivity and optical transparency in visible-infrared (VIS-IR) region. Improvement in these two key properties of SnO2 is of technological importance. In order to find ways for these improvements in the present study, SnO2 thin films have been prepared by Thermal Evaporation (TE) in oxygen (O-2) partial pressure and Plasma Assisted Thermal Evaporation (PATE) using RF (13.56 MHz) O-2 plasma. Optical, structural, compositional and electrical properties of the deposited films have been investigated by varying substrate temperature in range of 250-350 degrees C keeping other process parameters constant. The optical transmission spectra measured in VIS-IR region of films deposited by PATE have higher transparency (similar to 80-90 %) in comparison to the films grown by TE (similar to 60-70 %). X-ray Diffraction (XRD) study reveal SnO & SnO2 phases present in the film. Also X-ray Photoelectron Spectrosocpy (XPS) analysis showed SnO2-x as the only content, which is in agreement to XRD results. Surface morphology study by Scanning Electron Microscopy (SEM) shows more needle shape grains in case of films deposited by TE as compared to PATE grown films. Both types of the films were subjected to Four-probe method for the measurement of resistivity, which is in the order of 10(-4) Omega-cm and 10(-3) Omega-cm for PATE and TE grown respectively.