Rift-associated ultramafic lamprophyre(damtjernite) from the middle part of the Lower Cretaceous(125 Ma) succession of Kutch,northwestern India: Tectonomagmatic implications

Mineralogical,geochemical and isotopic(Sr and Nd) studies on the recently reported ca. 124 Ma'anorogenic lamproite' dyke from the Palanpur area, Kutch seismogenic rift zone, northwestern India, are presented. We propose a new classification for the dyke as a damtjernite(ultramafic lamprophyre; UML)based on its porphyritic-panidiomorphic texture, abundance of phlogopite, presence of nepheline in the groundmass, and the composition of liquidus phases such as olivine, phlogopite, magnetite, and clinopyroxene(diopside). The Palanpur UML is primitive(Mg# =74-77),silica-undersaturated(SiO_2<40 wt.%),potassic to slightly sodic in nature, and is strikingly similar to the ～69 Ma UML dykes and sills of the Tethyan Indus suture zone, which are considered as the earliest yet known manifestations of the Deccan Large Igneous Province(LIP). Bulk-rock(^(87)Sr/^(86)Sr)_i(0.70460-0.70461) and ε_(N)d(t)(+2.56 to-0.69) of the Palanpur UML signify derivation from a slightly depleted mantle source similar to that of asthenospheric magmas such as OIB. This is further attested to by the high incompatible trace element ratios(viz., La/Ba, Nb/U, Nb/La and Ta/Yb) that are typical of plume-type magmas. However, the Neoproterozoic T_(DM) depleted mantle Nd model ages( ～655-919 Ma) also necessitate some involvement of a lithospheric mantle component in its genesis. High bulk-rock Fe_2 O_3~t and TiO_2 contents require the involvement of a fertile peridotitic mantle source, whereas high La/Yb(60-80) implies a control by residual garnet. Higher Rb/Sr and lower Ba/Rb suggest phlogopite as a residual phase and high Nb and lower La/Sm favour carbonatite, rather than silicate melt as metasomatising agent. Low degrees of partial melting of a primitive garnet lherzolite mantle can account for the observed REE patterns in the Palanpur UML. The Palanpur UML shares a temporal similarity to the Kerguelen plume-derived Rajmahal basalts and associated alkaline rocks from the eastern India. The tectonomagmatic significance of its emplacement during the mid-Cretaceous vis-a-vis various models involving the timing of eruption of the Deccan and the Rahmahal Traps and the rifting in the Kutch basin induced by far-field plate reorganization is evaluated.

Structural,optical and antimicrobial properties of pure and Agdoped ZnO nanostructures

In the present work,zinc oxide(ZnO)and silver(Ag)doped ZnO nanostructures are synthesized using a hydrothermal method.Structural quality of the products is attested using X-ray diffraction,which confirms the hexagonal wurtzite struc-ture of pure ZnO and Ag-doped ZnO nanostructures.XRD further confirms the crystallite orientation along the c-axis,(101)plane.The field emission scanning electron microscope study reveals the change in shape of the synthesized ZnO particles from hexagonal nanoparticles to needle-shaped nanostructures for 3 wt%Ag-doped ZnO.The optical band gaps and lattice strain of nanostructures is increased significantly with the increase of doping concentration of Ag in ZnO nanostructure.The anti-microbial activity of synthesized nanostructures has been evaluated against the gram-positive human pathogenic bacteria,Staphylococcus aureus via an agarose gel diffusion test.The maximum value of zone of inhibition(22 mm)is achieved for 3 wt%Ag-doped ZnO nanostructure and it clearly demonstrates the remarkable antibacterial activity.

Cation Distribution in Lithium Ferrite(LiFe_(5)O_(8))Prepared via Aerosol Route

Nano size lithium ferrite was prepared through aerosol route and characterized using TEM, XRD, magnetic measurements and M?ssbauer spectroscopy. The particle size of as obtained samples were found to be ~10 nm through TEM, that increases upto ~80 nm on annealing at 1200 oC. The unit cell parameter ‘a’ calculated using XRD, confirms the formation of ?-LiFe5O8. Room temperature M?ssbauer spectra of as obtained sample of all the ferrites exhibited broad doublet suggesting super paramagnetic nature. This doublet further resolved into two doublets and assigned to the surface region atoms and internal region atoms of the particles. The annealed samples (1200 oC) show broad sextets, which were fitted with two sextets indicating different local environment of both tetrahedrally and octahedrally coordinated Fe-cation. Cation distribution obtained from the X-ray, magnetic and M?ssbauer data confirms that the three fifth of the iron atom goes in to the octahedral site.

Influence of Sputtering Pressure on the Structure and Mechanical Properties of Nanocomposite Ti-Si-N Thin Films

Nanocomposite Ti-Si-N thin films have been deposited on Si （100） substrate by direct current/radio frequency （DC/RF） magnetron sputtering. The effect of varying deposition parameters on the structure and mechanical properties of Ti-Si-N films has been investigated by characterization techniques such as X-ray dif- fraction （XRD）, field emission scanning electron microscopy （FE-SEM）, atomic force microscopy （AFM） and nanoindentation, respectively. XRD analysis of the thin films exhibit all （111）, （200） and （220） peaks initially with varying sputtering pressure, but （111） peak dominates at higher sputtering pressure. The crystallite size calculated from XRD peaks shows that it increases with increasing sputtering pressure. Microstructural analy- sis reveals that the dense blurred grains transform into uniform grains in the films and shows porosity with increasing sputtering pressure. The surface roughness of the Ti-Si-N films increases with varying sputtering pressure. The hardness and Youngrs modulus values of Ti-Si-N films are 33.7 and 278.6 GPa, respectively, with 0.7 Pa sputtering pressure but it decreases with further increase in sputtering pressure due to an increase in porosity of the films.

Structural,Wettability and Optical Investigation of Titanium Oxynitride Coatings:Effect of Various Sputtering Parameters

The objective of the present work is to investigate the effect of various sputtering parameters such as nitrogen flow rate, deposition time and sputtering pressure on structural, wettability and optical properties of titanium oxynitride films deposited on glass substrate by reactive magnetron sputtering. The X-ray diffraction graphs of titanium oxynitride films show evolution of various textures of TiO=N and TiN phases with increasing nitrogen flow rate and deposition time, but an increase in sputtering pressure from 4.0 to 8.0 Pa results in decline of various textures observed for TiO=Ny and TiN phases. The stress and strain calculated by sin2~ method are compressive, which decrease with increasing nitrogen flow rate from 55 to I00 sccm （standard cubic centimeter per minute） and increase with increasing deposition time from 80 to I40 min due to atomic penning effect and increasing thickness of the deposited films. The titanium oxynitride films have contact angle values above 90 deg., indicating that films are hydrophobic. The maximum contact angle of I09.1 deg. is observed at deposition time of 140 min. This water repellent property can add value to potential protective, wear and corrosion resistant application of titanium oxynitride films. The band gap decreases from 1.98 to 1.83 eV as nitrogen flow rate is increased from 55 to 100 sccm; it decreases from 1.93 to 1.79 eV as deposition time is increased from 80 to 140 min as more nitrogen incorporation results in higher negative potential of valence band N2p orbital. But it increases from 2.26 to 2.34 eV for titanium oxynitride films as sputtering pressure increases from 4.0 to 8.0 Pa.

Influence of Sputtering Gas on Morphological and Optical Properties of Magnesium Films

The influence of sputtering gas（He Ar） on the structural properties of Mg thin films has been investigated.The optical property（reflectance） that results from the growth of films at varying substrate temperatures（Tsub） was also studied.The deposited films were characterized by using X-ray diffraction（XRD）,field emission scaning electron microscopy（FE-SEM）,atomic force microscopy（AFM） and UV-Vis-NIR spectrophotometer.The smaller crystallite size and lower deposition rate were observed in the presence of Helium atmosphere compared to Argon.Morphology of the films shows 2D hexagonal geometry of grains in the deposition temperature range（Tsub≈50-150℃） in both the sputtering gases.The surface roughness of the polycrystalline films were found to increase with increase in the deposition temperature of both ambient gases.Optical reflectance of Mg films was measured in near infrared region and larger reflectance was observed from Mg films sputtered in He atmosphere compared to that in argon.