Characterization of silica polymorphs in kaolins by X-ray diffraction before and after phosphoric acid digestion and thermal treatment

Kahraman, Sibel; Önal, Müşerref; Sarıkaya, Yüksel; Bozdoğan, İhsan

doi:10.1016/j.aca.2005.07.045

Cited by 37 publications

(13 citation statements)

References 21 publications

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“…The high-angle XRD pattern (Figure 1 b) shows only two diffraction peaks at 2 q values of 44.398 and 64.548 corresponding to the sample holder and one broad peak at a 2 q value of approximately 238 corresponding to glass-like amorphous silicate nanoparticles. [12] Analysis of the SEM image of the template-free Mn/KIL-2 ( Figure 2) suggests that the main type of porosity in the sample is the so-called interparticle or textural porosity. Indeed, the textural porosity of the material can be better observed by using HRTEM.…”

Section: Resultsmentioning

confidence: 99%

MnO_x Nanoparticles Supported on a New Mesostructured Silicate with Textural Porosity

Tušar

Ristić

Mali

et al. 2010

Chemistry A European J

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A two-step synthesis of a novel mesostructured silicate, KIL-2, and its manganese-containing analogue, Mn/KIL-2, has been developed. KIL-2 possesses interparticle mesopores with pore dimensions between 5 and 60 nm and a surface area of 448 m(2). The mesopores are formed by the aggregation of silica nanoparticles, which creates a network with interparticle voids. The particle size and the pore diameters depend on the temperature of the ageing step (first step) and on the solvothermal treatment in ethanol (second step), respectively. Mn/KIL-2 contains octahedrally coordinated Mn(3+) (80%) and tetrahedrally coordinated Mn(2+) (20%) ions. Mn(3+) ions are present in the extra-framework MnO(x) nanoparticles with typical dimensions of 2 nm, which are homogeneously distributed throughout the material. Mn(2+) ions occur as isolated manganese framework sites. The material is also able to retain its structure characteristics after the hydrothermal treatment in boiling water. Because of its non-toxic nature and cost-effective synthesis, Mn/KIL-2 thus exhibits properties that are needed for an environment-friendly catalyst.

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Section: Resultsmentioning

confidence: 99%

MnO_x Nanoparticles Supported on a New Mesostructured Silicate with Textural Porosity

Tušar

Ristić

Mali

et al. 2010

Chemistry A European J

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“…Two XRD peaks at around 40°-70°are observed, which correspond to the MoS 2 (103) and Ti (103), respectively (Ma et al 2009;Firouzi-Arani et al 2010). Full with at half maximum (FWHM) of the peak is inversely related to the crystal size (Kahraman et al 2005). A very sharp, narrow Ti XRD peak is observed when the relative percentage of the Ti target is higher.…”

Section: Characterizationmentioning

confidence: 84%

Effect of sputtering power on friction coefficient and surface energy of co-sputtered titanium and molybdenum disulfide coatings and its performance in micro hot-embossing

et al. 2013

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Si micromolds are common for fabrication of polymer-based microfluidic devices by hot-embossing because of the well established fabrication methods for Si, e.g., deep reactive ion etching, for favorable surface finish and accuracy. The problems with low yield, poor reproducibility, premature failure and limited lifetime of a Si micromold are induced by high friction and surface adhesion generated during demolding. Therefore, Titanium (Ti) and molybdenum disulfide (MoS 2 ) coatings were deposited on Si micromolds via magnetron co-sputtering at various combinations of target powers to improve its surface properties. Coating composition, crystallographic orientation, roughness, critical load, hardness, friction coefficient and surface energy were measured by X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy, scratch testing, nanoindentation, ball-on-disc tribometry and the contact angle method respectively. A statistical design of experiment matrix was used to investigate the effect of the Ti and MoS 2 target powers on the friction coefficient and surface energy of the coatings. From this designed experiment, it was observed that increasing MoS 2 target power was associated with increasing surface energy and decreasing friction coefficient and target powers had statistically significant effects on these parameters. Crystallinity, roughness and hardness of the coatings increased with increasing Ti concentration. A mathematical model of the effects of Ti and MoS 2 target powers on the friction coefficient and surface energy of the coatings has been fit to the experimental results using the response surface method. Uncoated and MoS 2 -Ti coated Si micromolds were used in hot-embossing for a comparative study on replication performance of uncoated and various coated micromolds. Hotembossed PMMA microstructures showed that coating improve replication performance of Si micromolds. Si micromold coated with co-sputter of Ti and MoS 2 at power of 300 and 75 W respectively, showed better replication quality among the selected target powers.

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“…The rheological properties of the Na 2 CO 3 activated samples [24], some of the physicochemical properties of the heat treated samples [25], and the adsorptive properties of the H 2 SO 4 activated samples [26] of this bentonite were investigated in our previous studies. It was seen that the bentonite was dissolved completely during H 3 PO 4 digestion at 240°C for 12 min [20,21,23].…”

Section: Methodsmentioning

confidence: 99%

“…The paracrystallinity of opal increases permanently by the heat treatment, but the crystallinity of a-cristobalite does not [22]. Based on the facts, opals can be distinguished from a-cristobalite in natural raw materials by the X-ray diffraction analyses before and after orthophosphoric acid digestion and thermal treatments [23]. The aim of this study is the examination of the increasing in paracrystallinity of an opal-CT found in a bentonite by heat treatment.…”

Section: Introductionmentioning

confidence: 98%

The effect of heat treatment on the paracrystallinity of an opal-CT found in a bentonite

Önal

Sarıkaya

2007

Journal of Non-Crystalline Solids

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Characterization of silica polymorphs in kaolins by X-ray diffraction before and after phosphoric acid digestion and thermal treatment

Cited by 37 publications

References 21 publications

MnO_x Nanoparticles Supported on a New Mesostructured Silicate with Textural Porosity

MnO_x Nanoparticles Supported on a New Mesostructured Silicate with Textural Porosity

Effect of sputtering power on friction coefficient and surface energy of co-sputtered titanium and molybdenum disulfide coatings and its performance in micro hot-embossing

The effect of heat treatment on the paracrystallinity of an opal-CT found in a bentonite

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Characterization of silica polymorphs in kaolins by X-ray diffraction before and after phosphoric acid digestion and thermal treatment

Cited by 37 publications

References 21 publications

MnOx Nanoparticles Supported on a New Mesostructured Silicate with Textural Porosity

MnOx Nanoparticles Supported on a New Mesostructured Silicate with Textural Porosity

Effect of sputtering power on friction coefficient and surface energy of co-sputtered titanium and molybdenum disulfide coatings and its performance in micro hot-embossing

The effect of heat treatment on the paracrystallinity of an opal-CT found in a bentonite

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MnO_x Nanoparticles Supported on a New Mesostructured Silicate with Textural Porosity

MnO_x Nanoparticles Supported on a New Mesostructured Silicate with Textural Porosity