Iranian Journal of Crystallography and Mineralogy
Year:2009 | Volume:16 | Issue:4|Papers Count:14

Triglycine sulfate, TGS, and its phosphated counterpart, TGSP, have been grown by saturation solution method and were investigated for growth conditions and crystallographic parameters.Structural analysis equipments such as X-ray diffraction and back-scattering laser micro-Raman spectroscopy have been employed for the investigation of the grown crystals and the experimental results obtained for the pure TGS and doped TGSP crystals are presented. We place great emphasis on the influences of the orientation of the seed crystal and also phosporic acid addtion to the quality of the final grown crystals and the changes in the polarization has been studied by using a special electrical circuit and recording the hysteresis loops of the pure and doped crystals.

The determination of mineral quantities is one of the primary purposes of petrology and economic geology studies. When producing skarn zonation, it is necessary for the quantities of minerals in each zone to be known. Currently, various methods of determination for mineral quantities in rock bodies have been developed, but a rapid, accurate and economic method for distinguishing 3D mineral distribution has not yet been understood. This study introduces such a method for distinguishing 3D mineral distribution based on image sequence modelling of rocks. In the studied area, -Hassan-Abaad of Taft, central Iran- garnet is one of the most important and most frequent minerals found in skarns and is present in a variety of types and places. For our study, we sampled a very thin layer of rock (300 microns) and prepared a digital photo at every stage of our analysis. Prepared images were analyzed using MATLAB software. Each value of the image with its x, y and z coordinates was stored in a new matrix. Matrices were modelled in RockWorks and filtered based on the mean standard deviation of the modelled data, producing garnet networks. The studied zone had 31.4% garnet, allowing to be considered a garnet- wollastonite zone. This method is also useful for different calculations, such as: determining rock type, field zonation, calculation of the amount of mine and waste material, fluid inclusion studies and distinguishing type and volume of rock porosity.

The occurrence of palygorskite and its formation conditions in soils and sediments were studied along a transect covering granitic hilly lands to marly hilly lands in southern Mashhad. Based on formation conditions, amount and morphology, three kinds of palygorskite including high-amount palygorskite with long fibers in gypsiferous marl and basal part of deep loess deposits with high salinity, moderate-amount palygorskite which was mostly transported in association with carbonates and gypsum during calcic and gypsic horizon formation, and small-amount aeolian transported detrital palygorskite in non-altered loess deposits were distinguished. Palygorskite occurrence in Miocene marl is in line with the former investigations in central Iran. It shows similar conditions prevailing in this region and central and southeastern Iran and the formation of shallow and saline lakes and lagoons following the disappearance of the Tethyan seaway. Similar investigations around the world confirm that Tertiary sediments are the major source of palygorskite in the world.

The chromite deposits in the khoy area have lenticular, tubular and vein-like shapes which are found in serpentinized hurzburgite. Chromite and serpentine are major minerals and hematite and magnetite are minor phases in the chromitic ores .Furthermore, Fe, Ni, Cu, Co, Zn, Ru, Os, Ir, La, Ce, Gd and S elements are found as base metal sulfides (BMS), sulfides of pelatinum group elements (PGE), metal oxides, native elements, natural alloys and solid inclusions in chromite grains and or in serpentinic groundmass. These minerals have very fine grain sizes and recognitions of them by ore microscopic metod were limited, so the investigations were continued by EMPA. The majority of these minerals has secondary origin and is related with serpentinization procceses and only a few of them have primary origin. Among sulfide minerals bravoite, pyrotite, milerite, linaite and pyrite has secondary origin, wheras pentlandite has primary one. Chalcopyrite has been formed in two generations, as both primary and secondary origins. Among primary PGE minerals lourite ((Ru, Os, Ir)S2) is considerable, which was found as a solid inclusion in the chromite grain and has primary origin. Native metals and natural alloys such as nickel,copper,iron and josephinite (Ni3Fe) have been formed in microfracturs of chromite grains filled by serpentine. A few REE-rich compositions were found in microfracturs also and have secondary origin.

In this research, an ancient Iranian ceramic technology, which was published previously for the first time, has been used to produce various colored ceramic glazes. The color of such ancient glazes was always blue and the suitable body for that is unique due to high quartz content. There is no report of other color productions in productive workshop and scientific publications. The basic purpose of this research was to study the laboratory preparation of colored glazes without lead using the "sedimentations process". As a result of a series of experiments, we prepared colored ceramic glazes to determine the main factors in this process based on the unique oriental technique.

Diabases, pillow lavas and basaltic flows in the Nain-Dehshir ophiolites are marked with flat to slightly depleted pattern in REE chondrite-normalized diagram and are characterized by depletion in HFSE and enrichment in LILE. This geochemical behavior can be considered for lavas erupted in arc-related environments. Clinopyroxene in these rocks shows low content of TiO2 and resemble those found in island-arc tholeiites. These characteristics are consistent with back-arc formation during middle to upper Cretaceous, due to the oblique subduction of Neotethyan Ocean along the active continental margin of the central Iranian block.

Terbium oxide doped tetraborate glasses were prepared from the reaction of Tb2O3 and Na2B4O7 .10 H2O on reagent grade. At first, the base borate glass of Na2B4O7 was prepared by melting dehydrated borax at 1000 oC for 30 min and then the obtained base glass was crushed and powdered. Appropriate amounts of Tb2O3 (5-20 mol %) and Na2B4O7 powdered glass were mixed and melted at 1200 oC for 15 min. By transferring the melt in a cold steel sample holder and pressing, the final glasses were obtained. To avoid self crushing of the obtained glass samples, they were annealed at 300˚C for 1h. The density of the samples, measured by using Archimedes’s principle, showed that the doping of Tb2O3 in Na2B4O7 increases the density of the glass. The infrared spectra of the glasses in the range of 4000 - 400 cm-1 shows that the addition of Tb2O3 did not introduce any new absorption band in the infrared spectrum of pure sodium tetraborate glass. Comparing of the IR spectral features of the Tb+3 doped glasses with undoped glass show that the evolution of the IR spectral bands is related to the structural changes produced by varying of Tb+3. UV Spectroscopic study of such glasses shows that the addition of terbium oxide shifts the optical absorption edges towards lower energies. The fluorescence properties of (1-x) Na2B4O7.xTb2O3 glass system were investigated by means of the emission Spectroscopy with excitation by 377 nm light. The glass presented intense ~ 550 nm green luminescence.

Mineral assemblages, reaction textures and mineral composition of the metapelitic rocks from the Mahneshan area in NW Iran are studied to reconstruct the reaction history of the rocks. The phase relation on the real mineral chemistry AFM, AFMn compatibility diagrams and mineral isograds in chloritoid-free and chloritoid-bearing metapelites of Mahneshan Complex were studied in order to determine the reaction history. The main minerals in the graphitic metapelites (chloritoid-free schist) of the Bolandparchin are garnet, staurolite, andalusite, kyanite, fibrolite, biotite, muscovite and quartz. The isograds are typical Barrovian. Chloritoid-bearing metapelites of the area contain the minerals garnet, staurolite, chlorite, muscovite, chloritoid and quartz. The isograds are not compatible with Barrovian type, but reflect the first appearance of chloritoid in the aluminous bulk compositions. Phase relations on the AFM and AFMn compatibility diagram are used to find the metamorphic reactions in both chloritoid-bearing and chloritoid-free rocks.

The reaction of cadmium(II) nitrate hexahydrate with the proton-transfer compound (pipzH2)(ox) (where pipz=piperazine and oxH2=oxalic acid), in aqueous solution leads to the formation of the title polymeric compound (C2H6CdO7)n. This compound crystallizes in the triclinic system, space group Pī with two formula in the unit cell. The unit cell parameters are: a=5.998 (4) Å, b=6.634 (5) Å, c=8.482 (6) Å, a=74.679 (10)o, b=74.348 (11)o and g=81.112(11)o. The final R value was 0.087 for 1309 measured reflections. The CdII ion is seven-coordinated by five O atoms of oxalate ions as tetradentate bridging ligands and two O atoms of coordinated water molecules with distorted pentagonal bipyramid geometry around the central atom. The asymmetric unit also contains one water molecule. The crystal structure is stabilized by O–H…O hydrogen bonds, linking the molecules into a three-dimensional framework, which results in the formation of a supramolecular structure.

We have chosen an Ising ASYNNNI (ASYmmetric Next Nearest Neighbor Interaction)  model under a grand canonical regime to investigate structural phase transition from a high symmetric tetragonal (Tet) to a low symmetric orthorhombic in YBa2Cu3O6+x, 0<x<1, HTc system. Ordering process for absorbed oxygens from an external gas bath into the basal plane of the layered system is studied by Monte Carlo Glauber dynamics which focuses on the effect of chemical potential in the bath on the oxygen diffusion inside the basal plain, as well. It is predicted short range super-lattice phases called orthorhombic II and III (OII, OIII) and also a long range orthorhombic I (OI) phase, corresponding to the oxygen stoichiometry, x, and temperature. It is consistent with literatures and confirmed by our ND studies (ILL, France) too.

Field evidences, petrographic features and geochemical studies show that the garnet-muscovite granitoids of Boland Parchin area are S-type and they have sharp contact with the host rocks (metamorphic rocks). Granitoids of Boland Parchin contain minerals such as quartz, K-feldspars, plagioclase, biotite and Al-rich minerals (such as muscovite and garnet). Chemical composition of K-feldspars, plagioclase, biotite, muscovite and garnet in the studied samples show that K-feldspars are Or-rich component, plagioclase are Ab-rich, muscovite flakes are rich in the muscovite end-member, phlogopite-annite is the dominant constituent in biotite and chemical composition of the analysed garnets show that they are Alm-rich. Temperature and pressure have been calculated 600 °C and 5-8 Kbar respectively, for the formation of the granitoid rocks. All temperatures obtained from feldspar thermometry reflect sub-solidus re-equilibrium of the feldspars. Lack of equivalent extrusive rocks, existence of restitic micaceous enclaves (restitic biotite), mineralogical features (existence of muscovite and garnet) and chemical characteristics (peraluminous) indicate that Boland Parchin granitoids are S-type. Therefore the rocks are produced from partial melting of metapelites.

In this contribution, the Co doped SnO2 transparent semi-conducting films are prepared by spray pyrolysis technique and the influence of N2-and Ar-ambient annealing on their structural, electrical and optical properties are studied. The SnO2:Co thin films were deposited on the glass substrate at substrate temperature of 480 oC using an aqueous-ethanol solution consisting of tin and cobalt chloride. Doping levels of cobalt chloride have been changed from 0 to 14 wt. % in solution. Analysis of the X-ray diffraction patterns show that ‘a’ and ‘V’ parameters of the tetragonal unit cell decrease with increasing impurity content, while c parameter pass through a minimum for a acceptor dopant concentration of 8 wt. % or [Co]/[Sn] atomic ratio equal to 20 atm.% in solution. The N2-and Ar-ambient annealing causes increase of the electrical resistivity, band gap energies, and transparency of the cobalt doped samples.