Browsing by Author "Hatipoglu, M"

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    Third-order optical nonlinearities of Cu and Tb nanoparticles in SrTiO3
    Cetin, A; Kibar, R; Hatipoglu, M; Karabulut, Y; Can, N
    Some results of optical and nonlinear-optical properties of Cu and Tb nanoparticles implanted in SrTiO3 (STO) crystal are presented. The non-resonant third-order optical nonlinearities have been investigated by degenerate four wave mixing (DFWM), pump-probe and Z-scan techniques using femtosecond laser pulses. (C) 2010 Elsevier B.V. All rights reserved.
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    Spectral, electron microscopic and chemical investigations of gamma-induced purple color zonings in amethyst crystals from the Dursunbey-Balikesir region of Turkey
    Hatipoglu, M; Kibar, R; Çetin, A; Can, N; Helvaci, C; Derin, H
    Amethyst crystals on matrix specimens from the Dursunbey-Balikesir region in Turkey have five representative purple color zonings: dark purple, light purple, lilac, orchid, and violet. The purple color zonings have been analyzed with optical absorption spectra in the visible wavelength region, chemical full trace element analyses (inductively coupled plasma-atomic emission spectroscopy and inductively coupled plasma-mass spectroscopy), and scanning electron microscopic images with high magnification. It can be proposed that the production of the purple color in amethyst crystals is due to three dominant absorption bands centered at 375, 530, and 675 nm, respectively. In addition, the purple color zonings are also due to four minor absorption bands centered at 435, 480, 620, and 760 nm. X-ray diffraction graphics of the investigated amethyst crystals indicate that these crystals are composed of a nearly pure alpha-quartz phase and do not include any moganite silica phase and/or other mineral implications. Trace element analyses of the amethyst crystals show five representative purple color zonings, suggesting that the absorption bands can be mainly attributed to extrinsic defects (chemical impurities). However, another important factor that influences all structural defects in amethyst is likely to be the gamma irradiation that exists during amethyst crystallization and its inclusion in host materials. This gamma irradiation originates from the large underlying intrusive granitoid body in the region of amethyst formation. Irradiation modifies the valence values of the impurity elements in the amethyst crystals. It is observed that the violet-colored amethyst crystals have the most stable and the least reversible coloration when exposed to strong light sources. This situation can be related to the higher impurity content of Fe (2.50 ppm), Co (3.1 ppm), Ni (38 ppm), Cu (17.9 ppm), Zn (10 ppm), Zr (3.9 ppm), and Mo (21.8 ppm).
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    Thermal properties of gem-quality moganite-rich blue chalcedony
    Hatipoglu, M; Tuncer, Y; Kibar, R; Çetin, A; Karali, T; Can, N
    In this study, thermal properties and thermal decompositions of dehydration behaviour of gem-quality translucent blue chalcedonies, without banding or crystalline centre structure, from the Sancakaya-Eskisehir region in Turkey were studied by means of X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometry (ICP-AES), Fourier transform infrared (FT-IR), thermoluminescence (TL), and simultaneously two thermal analyses of (DTA/TGA) spectroscopy. X-ray diffraction patterns of the blue chalcedony indicate the presence of two important chalcedonic silica phases with overlapped peaks at 4.26, 3.34, 2.28, 2.13, 1.82, 1.54, 1.38, and 137 A. During heating from the room temperature to 300 degrees C, the thermoluminescence pattern of the blue chalcedony shows a characteristic peak at 210 degrees C. This peak may be due to unusually high traces of the impurities S. Th, TI, U, and W. During heating from the room temperature to 1400 degrees C, the TGA pattern of the blue chalcedony indicates that the weight loss is due to the silanol water loss only, and that this loss occurs in a wide temperature range between about 170 and 954 degrees C. In addition, after making some corrections concerning the artefact mass gain, being due to the drift with buoyancy effect of the atmosphere in its TGA curve, the moganite-rich blue chalcedony shows a relatively lower mass loss of 0.202%. The DTA pattern of the blue chalcedony displays both endothermic and exothermic behaviours because of silica phase transformations. There are one distinctive sharp endotherm and three weaker endotherms at 806 degrees C. In addition, there is one distinctive sharp exotherm and one weaker exotherm at 1270 degrees C. (C) 2010 Elsevier B.V. All rights reserved.
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    Amethyst and morion quartz gemstone raw materials from Turkey: color saturation and enhancement by gamma, neutron and beta irradiation
    Hatipoglu, M; Helvaci, C; Kibar, R; Çetin, A; Tuncer, Y; Can, N
    Color-enhancement investigations without using heating treatment from dull or pale to ideal saturation and/or changes to the formation of the rarer attractive colors are widely conducted to revalue abandoned gem material sources in the world. Such an investigation is carried out on pale or dull purple-colored amethyst and smoky-colored morion samples, which are two important gem species of the crystalline quartz (SiO2) mineral that are currently abandoned in natural deposits in Turkey because of their unattractive coloration. The results of color enhancements observed on these samples, after irradiation with artificial gamma, neutron and beta beams, were examined by comparing with samples with the ideal color saturation and also with colorless samples, using optical absorption (OA) and radioluminescence (RL) spectroscopy. The ICP-AES analyses reveal that the main impurity elements of over 100ppm in abundance in these quartz species are aluminum, iron and titanium for amethyst, and aluminum, iron, titanium and manganese for morion. The OA spectra indicate that vivid purple coloration of amethyst is due to the transmittance at about 395-420nm band gap as a result of absorbance peaks at 375, 480 and 530nm. These absorbances may be related to the unusual oxidized small proportions of certain impurity ions, after being exposed mainly to gamma irradiation, such as Al(IV) from the total aluminum, Ti(V) from the total titanium and Fe(IV) from the total iron, respectively. However, the RL spectroscopy of amethyst samples before and after they were exposed to artificial gamma, neutron and beta radiation beams demonstrates that the ions most affected by irradiation are Fe(IV) first and Al(IV) and Ti(V) second, and these ions represent the RL peaks at 600, 720 and 495nm, respectively. The OA spectra indicate that dark smoky coloration in morion is due to a lack of transmittance at the visible region as a result of the absorbance peaks at 375, 450-490, 620 and 730nm. These absorbances also may be related to the unusual oxidized small proportions of certain impurity ions by irradiation, such as Al(IV) from the total aluminum, Ti(V) from the total titanium and Mn(III) from the total manganese, respectively. In addition, the buoyancies of these absorbance peaks in the visible region produce the color hues between light smoky and dark smoky colorations in morion samples. These oxidized ion states are more resistant and stable against environmental destructive conditions in comparison with amethyst. Thus, the dark smoky coloration of morion becomes dull or pale after relatively longer periods. But, the RL spectroscopy of morion before and after being exposed to gamma, neutron and beta irradiation beams demonstrates that the most induced ions from the irradiation are Mn(III) and Al(IV) first and Ti(V) second. These ions represent the RL peaks at about 400, 720 and about 500nm, respectively.
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    Effects of heating on fire opal and diaspore from Turkey
    Hatipoglu, M; Can, N; Karali, T
    Fire opal (SiO2 center dot nH(2)O) and diaspore [Al(OH)O] are two different precious and rare mineral species with high water content. While these species are being cut and polished to make gems, defect-induced weaknesses such as fragility, splintering, and cracking become apparent since the temperature of the mineral species may be increased to high temperatures during the process. These deformations may be broadly related to water loss (molecular (H2O) and hydroxyl (OH) group) and transformation of the base building components and/or inclusion minerals. In this study, thermal properties and thermal stability as dehydratial behaviors of both gem quality fire opal (SiO2 center dot nH(2)O) from the Saphane region (Kutahya, Turkey) and gem quality diaspore (AlOHO) from the Milas region (Mugla, Turkey), including some associated mineral inclusions, were studied by means of X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform-Infrared absorption (FTIR) spectroscopy and thermal analysis (DTA/TGA). During heating to 1400 degrees C, DTA/TGA patterns indicated that the weight losses of the fire opal and diaspore were due to the water loss only, and that these losses occur in the temperature ranges between about 342 and 722 degrees C in fire opal, and between about 592 and 718 degrees C in diaspore. In addition, after making some corrections concerning the mass gain observed, being due to the drift with buoyancy effect of the atmosphere, in their TGA curves, the fire opal shows a mass loss of 7.942%, and one distinctive sharp endotherm at 1089.99 degrees C and seven weaker endotherms, whereas the diaspore shows a mass loss of about 13.826%, and one distinctive sharpest endotherm at 650.47 degrees C and four weaker endotherms. (C) 2010 Elsevier B.V. All rights reserved.