Iranian Journal of Crystallography and Mineralogy
Year:2001 | Volume:9 | Issue:1|Papers Count:5

Alkali lamprophyre dykes of southern Amlash have been injected into the upper Cretaceous limestones and pillow lavas without any special trend. Based on this research the following results obtained: 1- On the basis of Mg, Fe, Ti, Al contents, three different types of mica has been identified.A: Mg enriched biotite as the first generation. B: Ti enriched biotite as the second one. C: Fe-Ti enriched biotite as the third generation. 2- The pyroxenes are diopside and they crystallized in three separate stages. The second generation of pyroxenes have high Ti, Fe, and they formed the fine matrix and the rims of pyroxenes of the first generation. The abundance of large crystals of biotite within these dykes make them economically valuable and can be excavated as biotite mine. Probable reserve of the mineral deposit, with respect to surface discoveries is estimated to be 7500 tons. These dykes haven't been reorted in any other places of Iran and they studied in this area for the first time.

Morphology and crystal size of zeolites have an important role for their specific use in industries. Many parameters are found to be highly important in the physical appearance of the final zeolite products. In this work, some of the most effective parameters influencing the crystal size and morphology of zeolite A such as temperature and aging time of the gel preparation, crystallization temperature and rate of mixing during the synthesis were studied. Phase identification, morphology and the particle size of final products were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques.

In this work ultrafine single phase SrFe12O19 powders were prepared using SrCc3 and FeCl3 as raw material. The materials were then milled in high energy mills for 0.5 to 24 hours. The powders were then calcined between 700 and 1000°C for 0.5 h with different heating rates. The calcined powders were then washed with deionized water for several times, to remove undesired stontium chloride salt. XRD examinations were used to characterize the prepared ferrites. To measure saturation magnetization and coercive force of the samples, a vibrating sample magnetometer was used. The magnetic results were compared with those obtained in conventional ceramic technique and were discussed according to core-shell model.

Research attempts on zeolites show structural and industrial importance of these inorganic compounds. In this regard, the synthesis of zeolites is of great importance, because their natural occurring counterparts are often impure. Zeolite Na-P with a silicon to aluminium ratio of one has a better ion exchange capacity than Na-A and can be used as a detergent builder. In this work, zeolite Na-P of high purity was successfully synthesized using commercial silica and alumina sources. Parameters such as H2O:A12O3, Na2O:A12O3 and SiO2:A12O3 molar ratios and crystallization temperature and time were investigated. So that the optimum condition was obtained. X-ray powder diffraction, infrared, scanning electron microscopy and elemental analysis were utilized for the characterization of the product.

AlPO-5 molecular sieves were synthesized hydrothermally in presence of 2-20% of vanadium in the primary gel composition. Triethylamine was used as a structure directing agent.  Aluminum oxy hydroxide and phosphoric acid were used as sources of aluminum and phosphorous of the gel, respectively. Crystallization was performed by heating the samples at 190°C for 18-72 hours to obtain highly crystalline materials. The samples containing 2-16% vanadium preserve their structure upon calcination at 550°C but structure of the sample containg 20% of it collaps at this temperature and tridymite is the produced phase. Methods of X-ray diffraction, energy dispersive X-ray spectrometry associated with scanning electron microscope, and diffuse reflectance spectroscopy were used for structural and chemical characterization of the materials.The evidences acquired from above methods show that some of the V (V) in the as-synthesized materials have been reduced to V (lV) during synthesis procedures. The DR spectra of the as-synthesized samples show three distinct 280, 580 and 750nm bands which the first one was attributed to the tetrahedral V (V) and the two later ones to tetrahedral V (IV). The samples containing higher amounts of vanadium (10%, 16%) show a 350 nm band on the shoulder of 280nm which was assigned to V (V) surface-grafted species.