Crystallographic Research Articles

Composition and paragenesis of daqingshanite from the Kamthai carbothermalite, Rajasthan, India

AbstractDaqingshanite in the Kamthai REE deposit (India) occurs as two paragenetic types: primary granular coarse grained crystals coexisting with primary carbocernaite, baryte and bastnäsite; and as aligned micro-ovoid globules within clasts of Sr-bearing calcite. Carbocernaite forming trellis-type lamellae in some of these calcite clasts do not represent exsolution and are considered as replacement textures as they formed subsequent to daqingshanite. The origins of the textural relations of the microglobules of daqingshanite to their host Sr-calcite cannot be unambiguously determined, although an exsolution origin is not considered feasible. The textures are similar to those of ‘chalcopyrite disease’ and as such could be interpreted as replacement features formed in a low temperature carbothermal environment which should facilitate replacement. Given that daqingshanite is an early crystallising phase it is also possible that cotectic crystallisation with Sr-calcite occurred, followed by subsolidus re-equilibration with recrystallisation along specific crystallographic planes in the calcite. The Kamthai REE deposit is best described as a low temperature carbothermalite microbreccia consisting of a wide variety of clasts resulting from the autobrecciation of rocks formed during, and after, the magmatic to carbothermal transition of an undetermined parental calcite carbonatite-forming magma. Many clasts have been replaced by late stage La-enriched carbothermal fluids mixed with exogenous water during the final low-temperature stage of evolution of the deposit.

Molecular Dynamics Study of Temperature Dependence of Grain Boundaries (100) in Pure Aluminum with Application of Machine Learning

As is known, grain boundary (GB) energy determines the mobility of GBs and their population in metals. In this work, we study the energy of GBs in the (100) crystallographic plane and in the temperature range from 100 to 700 K. The study is carried out using both the molecular dynamic (MD) method and machine learning approach to approximate the MD data in order to obtain functional dependence in the form of a feed-forward neural network (FCNN). We consider the tilt and twist grain boundaries in the range of misorientation angles from 0 to 90°. Also, we calculate the average and minimum energy over the ensemble of GB states, since there are many stable and metastable structures with different energies even at a fixed grain misorientation. The minimum energies decrease with increasing temperature, which is consistent with the results of other studies. The scatter of GB energies in the temperature range from 100 to 700 K is obtained on the basis of MD simulation data. The obtained energy spread is in reasonable agreement with the data from other works on the values of GB energy in pure aluminum. The predictive ability of the trained FCNN as well as its ability to interpolate between the energy and temperature points from MD data are both demonstrated.

Effect of Si doping on elastic-plastic fracture toughness (JIC) of T91 ferritic/martensitic steel in liquid lead-bismuth eutectic

This work was devoted to understanding the effect of Si doping (1.27 wt%) on elastic-plastic fracture toughness (JIC) of T91 ferritic/martensitic (F/M) steel in liquid lead-bismuth eutectic (LBE, Pb44.5Bi55.5, wt%) under various parameters. The results showed that Si doping significantly promoted occurrence of liquid metal embrittlement (LME) and led to more severe degradation of fracture toughness at 350 °C, especially in oxygen-poor LBE. The LME susceptibility of T91-Si steel was found to be nearly independent on the loading speeds, while T91 F/M steel exhibited a stronger LME effect when the loading speed was decreased from 0.02 mm/min to 0.002 mm/min. Oxygen concentration had a mild effect. Detailed microstructural analyses showed that the fracture behavior of the T91-Si steel in LBE environment at 350 °C was analogous to cleavage fracture and the crack propagation was mainly transgranular. The crack wall was quite rough and locally faceted to low-index crystallographic planes of {110}. Numerous dislocations were also present in the vicinity of the crack tip. No solid evidence of diffusion of Pb and Bi into the steel bulk was discovered even at the atomic scale, which strongly suggests a crack tip surface adsorption-based LME mechanism.

Study the characterization of ZnO and AZO films prepared by spray pyrolysis and the effect of annealing temperature

Spray-pyrolysis was used to successfully create ZnO and AZO (Al-doped ZnO) thin films on glass substrates at various annealing temperatures. Structure, morphology, and optical characteristics were investigated in relation to doping and annealing temperature using analytical techniques such as FTIR, UV–Vis spectroscopy, XRD, and FE-SEM. The films' singular-phase polycrystalline hexagonal Würtzite structure was revealed by XRD data, and the crystallographic plane for both AZO and ZnO was (0 0 2). Crystallite sizes are increased by raising the annealing temperature and adding Al-doping, which enhances surface morphology. where the diameters of the AZO crystallites expanded from 23.3 to 33.3 nm, whereas the ZnO crystallites grew from 27.8 to 28.5 nm. Scanning electron microscopy's morphology reveals that the surface particles' tiny, round shapes have changed to spherical clusters that resemble cauliflowers with increasing annealing temperatures. Notably, the ZnO film has a high transmittance, whereas the AZO film has a relatively low transmittance. Furthermore, at an annealing temperature of 400 °C, all films show notable absorbance, with the highest absorption seen at 400 and 413 nm for ZnO and AZO, respectively. The bandgap values at various annealing temperatures vary from 3.22 to 3.23 eV and 3.08–3.12 eV for ZnO and AZO, respectively. As the annealing temperature rose, the phenomena showed a drop in value.

Monolithic Use of Inert Gas for Highly Transparent and Conductive Indium Tin Oxide Thin Films.

Due to its excellent electrical conductivity, high transparency in the visible spectrum, and exceptional chemical stability, indium tin oxide (ITO) has become a crucial material in the fields of optoelectronics and nanotechnology. This article provides a thorough analysis of growing ITO thin films with various thicknesses to study the impact of thickness on their electrical, optical, and physical properties for solar-cell applications. ITO was prepared through radio frequency (RF) magnetron sputtering using argon gas with no alteration in temperature or changes in substrate heating, followed with annealing in a tube furnace under inert conditions. An investigation of the influence of thickness on the optical, electrical, and physical properties of the films was conducted. We found that the best thickness for ITO thin films was 100 nm in terms of optical, electrical, and physical properties. To gain full comprehension of the impact on electrical properties, the different samples were characterized using a four-point probe and, interestingly, we found a high conductivity in the range of 1.8-2 × 106 S/m, good resistivity that did not exceed 1-2 × 10-6 Ωm, and a sheet resistance lower than 16 Ω sq-1. The transparency values found using a spectrophotometer reached values beyond 85%, which indicates the high purity of the thin films. Atomic force microscopy indicated a smooth morphology with low roughness values for the films, indicating an adequate transitioning of the charges on the surface. Scanning electron microscopy was used to study the actual thicknesses and the morphology, through which we found no cracks or fractures, which implied excellent deposition and annealing. The X-ray diffraction microscopy results showed a high purity of the crystals, as the peaks (222), (400), (440), and (622) of the crystallographic plane reflections were dominant, which confirmed the existence of the faced-center cubic lattice of ITO. This work allowed us to design a method for producing excellent ITO thin films for solar-cell applications.

Superior photoelectrodes of nanostructured Mo-doped CuO thin film for green hydrogen generation from photoelectrochemical water-splitting

Green hydrogen has an audible echo in the clean energy field. In this piece of work, pure and Mo-doped CuO thin films were deposited at different substrate temperatures on the Indium Tin Oxide (ITO) by the DC/RF sputtering technique. The prepared samples were utilized to generate hydrogen gas within the photoelectrochemical water-splitting mechanism. Crystallographic planes (−111), and (200) were the preferred orientations for pure and Mo-doped CuO thin films. Moreover, the average crystallite size was doubled by Mo doping reaching 25.8 nm. FE-SEM microscopic image exhibits that the pure and Mo–CuO thin films have a regular distribution with a small size. The optical band gap has rosed by doping from 1.8 eV to 2.05 eV. Then, it increased to 2.3 eV and 2.4 eV at temperatures of 100 °C and 200 °C respectively. Pure and Mo–CuO thin films were applied as photocathodes for hydrogen generation with water water-splitting technique. The photoelectrochemical application revealed a photocurrent density of ∼2.25 mA/cm2 for Mo-doped CuO photoelectrode at room temperature. This optimum photoelectrode was studied for stability and electrochemical impedance. In addition, the incident photon to current efficiency (IPCE%) was 4.47 % at 500 nm. The applied bias photon to current conversion efficiency (ABPE%) was 4.25 % at −0.38V. As a result of the above, pure and Mo-doped CuO photoelectrodes are low-cost thin films and have a high-efficiency performance for green hydrogen generation industrially.

Elastic and breaking properties of epitaxial face‐centered crystals in neutron star crusts and white dwarf cores

AbstractCrystallization of dense matter in neutron star crusts and white dwarf cores may be similar to epitaxial crystal growth in terrestrial laboratories. However, in stellar crystals, the spacing between horizontal planes has to gradually increase with the outward movement of the crystallization front, tracing decrease of the electron density. This process produces Coulomb crystals with stretched rather than cubic elementary cells. We extend the analysis of the elastic and breaking properties of such crystals to the face‐centered (fc) lattice. Shear deformations orthogonal to the stretch direction have been studied for 22 crystallographic shear planes. A common property for all these planes is the reduction and eventual nulling of the breaking shear strain with deviation from the unstretched configuration. The effective shear moduli for deformations orthogonal to the stretch direction have been calculated. It is possible that the epitaxial crystallization in compact stars results in a formation of large‐scale crystallites or, at least, in growth of the whole crystallization front perpendicular to particular crystallographic planes. For fc structure growth orthogonal to the planes, we expect that, at any density, () of crystallite height is occupied by layers one (two) orders of magnitude weaker than the bulk of the crystallite. This may be important for realistic modeling of crustquakes on neutron stars.

Challenges in quantifying Pt concentrations in Pd alloys by using secondary ion mass spectrometry: Strong grain orientation effects

Palladium–platinum alloys were analysed by dynamic secondary ion mass spectrometry (SIMS) to investigate grain orientation effects that gave differences of up to 400% in the Pt/Pd count rate ratios, even within the same grain upon small rotations of a Pd sample with 1 wt% Pt. The sample had been homogenized by annealing, and the homogeneity was confirmed by X‐ray analysis in scanning electron microscopy (SEM). Grain orientations were determined by electron backscatter diffraction (EBSD). Crater depths were measured by white light interferometry (WLI). SEM images from the bottom of SIMS craters made in the same grain after small rotations around the sample surface normally showed different patterns of microfaceting for some rotation angles, probably exposing low‐index crystallographic planes. A complete understanding of the observed grain orientation effect is still lacking. However, factors such as ion mass, sputter rate, ion channelling, ion focusing, preferential sputtering, surface height, crater microfaceting and/or angle‐dependent sputtering seem to play a role. For these Pd–Pt alloys, the strong grain orientation effect adds another level of complexity when attempting to quantify concentrations and obtain depth profiles by SIMS. Without proper sampling and/or averaging, one could reach very wrong conclusions when comparing results from different samples.

Enhancing air stability of LiMg alloy anode through Yb segregation at grain boundaries

Owing to the ultrahigh theoretical specific capacity and the most negative electrochemical potential, lithium metal has become the most promising lithium battery anode material. However, it is highly susceptible to oxidation during industrial production and storage processes. The polycrystal surface of the lithium metal anode serves as the site for oxidation reaction, and the reaction pathway is inevitably influenced by the microstructure of the anode surface. especially the grain boundaries, which with higher activity than a crystallographic plane, leading to intercrystalline oxidation reactions. Within the LiMg@Yb alloy system, ytterbium (Yb) segregated at the grain boundaries, leading to a reduction in intercrystalline energy as predicted by Density Functional Theory (DFT) calculations. Thus, the LiMg@Yb alloy can effectively suppress intercrystalline oxidation reactions and enhance air stability. More impressively, even exposed to ambient air for 0.5 h, the LiMg@Yb-0.5||LFP full cell exhibited a higher capacity retention rate (80.7%) than the bare Li-0.5||LFP (35.9%) after 100 cycles. This work presents a new approach for enhancing air stability by inhibiting intercrystalline oxidation reactions between anodes and air.

Antibacterial activity of extracellular biosynthesized iron oxide nanoparticles against locally isolated β-lactamase-producing Escherichia coli from Egypt

Nowadays, extended spectrum β-lactamase (ESBL) producing Escherichia coli has been recognized and recorded worldwide as one of the main causing agents and a major contributor to nosocomial infections. The current study aimed to isolate and detect β-lactamase-producing E. coli and use it in the extracellular biosynthesis of iron oxide nanoparticles (Fe2O3 NPs). Fifteen Gram-negative (G-ve), lactose-fermenting, negative citrate and non-spore-forming coliform bacteria were isolated from the total bacterial isolates from water samples. Different tests were performed to detect β-lactamase-producing E. coli isolates including the chromogenic methods as acidimetric and iodometric techniques and the phenotypic methods as cloverleaf test and Masuda double-disc test. ESBL-producing E. coli was detected and confirmed by a modified double disc synergy test using ceftazidime, cefotaxime, ceftriaxone, amoxicillin combined with clavulanic acid, imipenem, cefepime, and cefoxitin. The quantitative assay of β-lactamase was done using a micro-iodometric assay. Among E. coli bacterial isolates, S1B1 isolate (the highest isolate of β-lactamase activity) was selected and tested for the extracellular biosynthesis of Fe2O3 NPs. The produced nanoparticles (NPs) were characterized by UV–visible spectroscopy, X-ray diffraction analysis, Fourier-transform infrared spectroscopy (FTIR), transmission electron microscope and Zeta analysis. Results confirmed the successful biosynthesis of Fe2O3 NPs which displayed an absorption peak at 346 nm and a Fe2O3 crystallographic lattice plane at (104). Fe2O3 NPs were negatively charged spherical-shaped NPs with an average size of ≈ 24 ± 2 nm. The FTIR spectrum refers to the presence of NPs-associated proteins which act as stabilizing and capping agents. Antibacterial activity of Fe2O3 NPs was tested against Staphylococcus aureus ATCC25923, Bacillus cereus ATCC6633 (G+ve bacterium), Pseudomonas aeruginosa ATCC27853 (G-ve bacterium), as well as the β-lactamase-producing E. coli S1B1 strain. Fe2O3 NPs revealed moderate to strong antibacterial action against the tested strains with a minimum inhibition concentration (MIC) ranging from 25 to 40 µg/ml.

Mechanism of mean stress sensitivity in Ti-6Al-4V under different stress ratios in high cycle fatigue

Initially, this article precisely determines that the “facet” on the fracture surface of the Ti-6Al-4V alloy during high cycle fatigue (HCF) loading under positive stress ratios, as determined by white light interferometry and transmission Kikuchi diffraction (TKD), originates from cracking along the slip planes that exhibit a grain orientated α grain in the loading direction, predominantly involving shear deformation along the crystallographic planes. The article emphasizes the crack initiation mechanisms in Ti-6Al-4V alloy related to internal microstructures under positive stress ratio HCF loading, elucidating relationship between texture-induced crack initiation and growth, and anomalous mean stress sensitivity. Under positive stress ratio fatigue loading, preferentially orientated texture regions tend to generate irreversible dislocations parallel to the basal plane, gradually accumulating within multiple locations to form persistent slip bands (PSBs), which, under the influence of internal stresses, sequentially collapse and rupture, leading to nucleation of microcracks. Upon encountering unfavorably oriented texture regions or grains, PSBs or existing microcracks experience dislocation accumulation, which in turn induce grain refinement, thereby causing further crack nucleation. Consequently, microcracks, through aggregation and coalescence during the fatigue loading sequence, form the main crack, ultimately precipitating fatigue failure and engendering the anomalous mean stress sensitivity observed in the Ti-6Al-4V alloy.

Elastic wave speeds, Debye temperature and microhardness of YX3 (X = In, Sn, Tl and Pb) intermetallic compounds

In the present work, we reviewed and report on the theoretical prediction of the longitudinal, transverse and average elastic wave veloci-ties, and the Debye temperature for some nonmagnetic YX3 (X = In, Sn, Tl, and Pb) intermetallic compounds with stable cubic AuCu3-type structure. The lattice parameters and the elastic constants used here are taken from the work of Abraham et al [1] using the general-ized gradient approximation (PBE-GGA). Our results are analyzed and compared with the available theoretical and experimental data, and in general a good agreement is found. The deviation between our value (224.4 K) of the Debye temperature θD for YSn3 material and the experimental one (210 K) is around 6.62%, while the deviation between our result (1401 m/s) of the transverse elastic wave velocity for YTl3 intermetallic material and the calculated one (1470 m/s) is about 4.93%. In addition the Young’s Modulus and Poisson’s Ratio of YX3 intermetallic compounds for the crystallographic planes (100), (110) and (111) are predicted.

Overlap and rotate - a simple method for predicting out-of-plane and in-plane orientations of heteroepitaxial thin films

The production of heteroepitaxial thin films is increasingly important due to their considerable utility in technical practice. This usability is determined by their specific physical and chemical properties influenced by the mutual crystallographic substrate-film orientation, both the out-of-plane and the in-plane. The possibility of predicting these orientations would reduce the time and financial burden of their experimental determination. This study shows how the out-of-plane and the in-plane orientation of heteroepitaxial film can be predicted by simply calculating number of overlapping atoms in a system of two overlapping crystallographic planes, one of which rotates relatively to the other. Coordinates of atoms in the crystallographic planes are taken from bulk structures, which contributes to the simplicity of the method. The average number of overlapping atoms (calculated from a 360° rotation) and the maximum number of overlapping atoms (including a corresponding angle) indicate the out-of-plane and the in-plane orientation, respectively. The method is tested on various substrate/film systems (SrTiO3/ZnO, Al2MgO4/ZnO, MgO/ZnO, MgO/CuO, Si/Al, MoS2/Au) and the results are compared with experimental data obtained from the literature. The good agreement with the experimental data shows this method to be reliable and sufficiently accurate for heteroepitaxial thin films.

Effects of structural defects on optical properties of InxGa1−xN layers and quantum wells

This review concentrates on the microstructure of InxGa1−xN layers and quantum wells (QWs) in relation to their optical properties. The microstructure of InxGa1−xN, with a constant In(x) concentration, shifts with layer thickness. Only layers below 100 nm for x = 0.1 are nearly defect-free. A photoluminescence peak is observed at 405 nm, in line with ∼10% In, suggesting band-edge luminescence. Layers with greater thickness and In content present a corrugated surface with numerous structural defects, including V-defects, causing redshifts and multi-peaks in photoluminescence up to 490 nm. These defects, resembling those in GaN, lead to a corrugated sample surface. Atomic force microscopy shows a 3.7-fold larger corrugation in samples with 20 QWs compared to those with 5 QWs measured on 2 × 2 μm2 areas. Like in GaN, dual growth on different crystallographic planes results in varied QW thicknesses, influencing optical traits of devices made from InxGa1−xN layers. The purpose of this review and the chosen subject is to highlight the significant contribution of Wladek Walukiewicz and his group to the current research on the properties of InxGa1−xN, which are crucial alloys in the field of optoelectronics.

In Vitro Antioxidant Activity of Green-Synthesized Zinc Oxide (ZnO) Nanoparticles Utilizing Extracts From Allium sativum.

The primary objective of this study was to develop an environmentally friendly and efficient method for synthesizing zinc oxide (ZnO) nanoparticles (NPs), utilizing extracts from Allium sativum (garlic) plants, characterizing the synthesized ZnO NPs using various analytical techniques, and assessing their antibacterial and antioxidant properties. The synthesis process involved utilizing extracts from garlic plants to create ZnO NPs. The NPs were subjected to comprehensive characterization through UV-visible (UV-vis) spectroscopy, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Antibacterial properties were assessed against different microbial strains. In vitro antioxidant properties were evaluated through 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assays. Bioactive compounds in the synthesized NPs were also identified. Analysis of the UV-visspectrum confirmed the synthesis of ZnO NPs with an approximate size of 280 nm, as indicated by the absorption peak in the surface plasmon resonance band. FTIR spectroscopy revealed the presence of functional groups such as hydroxyl and carboxyl groups. SEM analysis determined the dimensions of the NPs to be around 11 nm. XRD patterns exhibited distinct Bragg reflections, confirming specific crystallographic planes. In vitro antioxidant assays demonstrated a reduction in absorbance at 517 nm and 734 nm, indicating antioxidant activity. Antibacterial testing revealed inhibition zones against Escherichia coli, Staphylococcus aureus, Streptococcus mutans,and Enterococcus faecalis. The study successfully synthesized ZnO NPs using an eco-friendly method with garlic plant extracts. Characterization techniques confirmed the structural and chemical properties of the NPs. The synthesized NPsexhibited antioxidant and antibacterial activities, showcasing their potential for various applications. The identification of bioactive compounds further contributes to the understanding of the biological properties of the synthesized NPs.

Role of carbon in n-type bulk GaN crystals

In this work co-doping with silicon and carbon in gallium nitride grown by halide vapor phase epitaxy was performed. Native seeds of high structural quality with bowing radii of (0001) crystallographic planes higher than 15 m and threading dislocation density on the order of 5 × 104 cm−3 were used. The crystallized material was examined in terms of structural, optical, and electrical properties. For this purpose different characterization methods: X-ray diffraction, Raman spectroscopy, low-temperature photoluminescence, and Hall measurements, were applied. The physical properties of samples doped only with silicon and co-doped with carbon were analyzed and compared. However, during the crystallization process, due to high amount of Si and C, clusters of silicon carbide were unintentionally formed. The formation of these SiC clusters had an impact on the properties of the GaN crystals that were being studied. The research provides an initial insight into the complex studies of co-doping gallium nitride crystals. The results of this paper give us groundwork for more in-depth exploration of this topic.

The Influence of Crystal Orientation and Thermal State of a Pure Cu on the Formation of Helium Blisters

The factors that influence the formation of helium blisters in copper were studied, including crystallographic grain orientation and thermomechanical conditions. Helium implantation experiments were conducted at 40 KeV with a dose of 5 × 1017 ions/cm2, and the samples were then subjected to post-implantation heat treatments at 450 °C for different holding times. A scanning electron microscope (SEM) equipped with an electron backscatter diffraction (EBSD) detector was used to analyze the samples, revealing that the degree of blistering erosion and its evolution with time varied with the crystallographic plane of the free surface in different ways in annealed and cold rolled copper. Out of the investigated states, rolled copper with a (111) free surface had superior helium blistering durability. This is explained by the consideration of the multivariable situation, including the role of dislocations and vacancies. For future plasma-facing component (PFC) candidate material, similar research should be conducted in order to find the optimal combination of material properties for helium blistering durability. In the case of Cu selection as a PFC, the two practical approaches to obtain the preferred (111) orientation are cold rolling and thin layer technologies.

Low traces of acetone detection with WO3-based chemical sensors

This work presents the ability of WO3-based sensors to detect low traces of acetone, specifically within the range of 0.25–5 ppm, specific to the in-field atmosphere. The WO3 powder was synthesised through the hydrothermal method. Morpho-structural investigations showed a monoclinic structure and a good crystallization of the WO3 powder, containing well-grown and faceted grains along low-index crystallographic planes. The paste obtained by mixing the powder with propanediol was screen-printed as a thick layer onto commercial alumina substrates, obtaining the chemical sensors. A dynamic computer-controlled Gas Mixing System was utilized to ensure controlled airflow with variable relative humidity and acetone concentrations. The sensor response was explained based on physico-chemical equations, taking into consideration pre-adsorbed species of oxygen and water, both of which are relevant constituents of atmospheric conditions. The results highlight the applicative potential of WO3, having a good signal-to-noise ratio in relative humidity conditions up to 90% and a pronounced sensitive selectivity to acetone.

Green synthesis and characterizations of magnetic iron oxide nanoparticles using Moringa oleifera extract for improved performance in dye-sensitized solar cell

In this study, Moringa oleifera extract was used for the green synthesis of magnetic Iron Oxide (Fe3O4) nanoparticle. Natural dye from air-dried Carica papaya leaves was used as sensitizer along with commercially obtainable N719 Ruthenium dye. The optical absorptions between 350 and 650 nm confirmed the formation of the nanoparticle. After adding the nanoparticle to the TiO2 and loading it with dye, the absorbance in the visible range dramatically increased. The formation and stabilization of the nanoparticle may have been aided by the functional groups, according to the FTIR results. With an average crystallite size of 35.13 nm, the XRD patterns demonstrated the nanoparticle's crystalline nature. The morphologies of the nanoparticle demonstrated that it was well-formed and homogeneously dispersed. The presence of iron and other component elements was confirmed by the EDX spectra. The production of 40.83 nm-sized nanoparticles on average was further verified by the TEM micrograph, and the samples' crystallographic planes were identified by the SAED patterns. The photo-electrochemical performance of the DSSCs showed that the efficiencies increased significantly with percentage increase of 90.1% and 89.3% for Carica papaya and Ruthenium dyes, respectively. The green-synthesized Fe3O4 nanoparticle exhibited good properties for application in DSSC.

Low temperature relaxor behaviour of SrBi1.5La0.5Nb2O9 ceramics

Bismuth layered compound with the composition SrBi1.5La0.5Nb2O9 has been prepared using conventional solid-state reaction method. Crystallographic planes have been identified using X-ray diffraction studies. The dielectric studies have been done as a function of frequency and temperature. Low temperature dielectric measurement shows phase transition in which peak dielectric constant shifts from 260K to 280K with the increase in frequency from 1 kHz to 1 MHz. Room temperature dielectric constant has been found to be nearly frequency independent for this composition making it a potential candidate for the capacitor applications. The prepared ceramic was modelled using the Vogel – Fulcher relationship.