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    Ca2+/Mg2+ co-substituted strontium nanohexaferrites: magnetic investigation and Mossbauer analysis
    (Springer, 2019) Almessiere, Munirah A.; Slimani, Yassine; Demir Korkmaz, Ayşe; Güngüneş, Hakan; Nawaz, Muhammad; Shirsath, Sagar E.; Ercan, İsmail
    We report a comprehensive evaluation of the microstructures, magnetic, and hyperfine traits of Ca2+/Mg2+ co-substituted strontium nanohexaferrites (SHFs) of chemical compositions Sr1-2xCaxMgxFe12O19 (x <= 0.1). These SHFs were prepared using sol-gel unified auto-combustion strategy and characterized by diverse analytical measurements to determine the effects of Ca2+/Mg2+ co-substitution on the aforesaid properties. XRD and high resolution transmission electron microscpe (HRTEM) analyses confirmed the nucleation of HF nanocrystallites. UV-visible diffuse reflectance (DR-UV-Vis) spectra were used to evaluate the optical band gap of the proposed SHFs, which was reduced with the increase in co-substitution contents. The Fe-57 Mossbauer spectra was exploited to assess the quadrupole splitting, spectral line-width variation, isomer shift, distribution of cations (Ca2+ and Mg2+), and hyperfine magnetic fields. Measured magnetic parameters such as saturation magnetization, remanence, squareness ratio (SQR), coercivity, and magnetic moment were significantly improved due to the Ca2+/Mg2+ co-substitution. All the prepared SHFs revealed ferrimagnetic nature both at 10 and 300 K. Achieved SQR values approximate to 0.5 of the studied SHFs clearly disclosed their single domain character possessing uniaxial anisotropy. [GRAPHICS] .
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    Ca2+/Mg2+ co-substituted strontium nanohexaferrites: magnetic investigation and Mossbauer analysis (vol 93, pg 228, 2020)
    (Springer, 2020) Almessiere, Munirah A.; Slimani, Yassine; Demir Korkmaz, Ayşe; Güngüneş, Hakan; Nawaz, Muhammad; Shirsath, Sagar E.; Ercan, İsmail
    [Abstract Not Available]
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    Exploration of catalytic and cytotoxicity activities of CaxMgxNi1-2xFe2O4 nanoparticles
    (Elsevier Science Sa, 2019) Nawaz, Muhammad; Almessiere, Munirah Abdullah; Almofty, Sarah; Dönmez Güngüneş, Çiğdem; Slimani, Yassine; Baykal, Abdulhadi
    The CaxMgxNi1-2xFe2O4 (x <= 0.05) nanoparticles (NPs) have been synthesized hydrothermally. The XRD analyses confirmed the purity of all products and their spherical morphology and compositions were explained by SEM, TEM, EDX and Elemental mapping analyses. Results confirmed the composition of CaxMgxNi1-2xFe2O4. The surface area of them was determined by BET analysis. Results indicated that when x is increased surface area of CaxMgxNi1-2xFe2O4 is decreased as compare with x = 0.0, however, at high composition (x = 0.05), surface area is increased. Catalytic activity of CaxMgxNi1-2xFe2O4 (x <= 0.05) NPs was studied for the reduction of 4-nitrophenol as a model compound. Reaction was monitored by UV-spectrophotometer at room temperature and at different times. Among different compositions of CaxMgxNi1-2xFe2O4, it was noticed that x = 0.04 exhibited more activity for the reduction of 4-nitrophenol and x = 0.03 was observed least active. Results suggested that CaxMgxNi1-2xFe2O4 could be useful material for catalytic applications. Cytotoxicity activity of CaxMgxNi1-2xFe2O4 (x <= 0.05) NPs against HCT116 (Human colon cancer cell line) cell line and MCF-7 (breast cancer cell line) was evaluated by using MTT assay. It was observed that CaxMgxNi1-2xFe2O4 (x <= 0.05) NPs exhibited less cytotoxicity. Due to less cytotoxicity, CaxMgxNi1-2xFe2O4 may also be useful in the field of biomedical applications.
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    Investigation of the crystal/magnetic structure, magnetic and optical properties of SrYxNbxFe12-2xO19 (x <= 0.05) hexaferrites
    (Iop Publishing Ltd, 2020) Almessiere, Munirah Abdullah; Slimani, Yassine; Güngüneş, Hakan; Nawaz, Muhammad; Alahmari, Firas S.; Manikandan, Ayyar; Baykal, Abdulhadi
    Series of Sr hexaferrites (HFs) co-substituted with Nb3+ and Y3+ ions (SrYxNbxFe12-2xO19 (x <= 0.05) were prepared via sol-gel combustion method. In addition to their optical, low temperature, magnetic properties and hyperfine interactions were investigated in detail. X-ray diffraction (XRD) patterns were considered proving both the formation and pureness of products. Mossbauer analysis indicated that the hyperfine field on iron nuclei at all sites decrease with substitution of Y3+-Nb3+ ions into Sr-hexaferrite as a result of changing the magnetic Fe3+ (5 mu(B)) ions by nonmagnetic Y3+ and Nb3+ ions. This leads to decreasing of the magnetic super exchange interaction between the ions. Measurements of AC susceptibility and ZFC-FC magnetizations implemented in a range from room temperature (RT) down to around 2 K. The analysis of M-FC-M-ZFC data proves the ferrimagnetic performance of different prepared HFs in the whole range of 2-325 K and a super-spin glass-like behavior was identified at minimal temperatures. The investigation of AC susceptibility revealed a weakening in the magnetic exchange interactions with the rise in the Nb3+ and Y3+ ions ratios.
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    Magneto-optical and microstructural properties of spinel cubic copper ferrites with Li-Al co-substitution
    (Elsevier Ltd, 2018) Slimani, Yassine; Güngüneş, Hakan; Nawaz, Muhammad; Manikandan, A.; El Sayed, H. S.; Almessiere, Munirah Abdullah; Sözeri, Hüseyin; Shirsath, Sagar E.; Ercan, İsmail; Baykal, Abdulhadi
    Nanospinel Li2xCu1-xAlyFe2-yO4 ferrites with composition x?=?y?=?0.0, 0.2, 0.3 and 0.4, were successfully synthesized via hydrothermal method. The effect of co-substitution (Li and Al) on structural, morphological and magnetic properties of CuFe2O4 nanoparticles were investigated using Powder X-ray Diffraction (XRD), Fourier-Transform Infrared spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM) and Mossbauer spectroscopic techniques. The cation distribution of all composition was calculated. Both XRD and FT-IR analyses confirmed the synthesis of single-phase spinel cubic product for all the substitutions. Mossbauer investigation showed that the Li1+ and Al3+ ions occupied B-sites. Nonetheless, some amounts of Li1+ occupy A-site. The magnetization hysteresis loops M (H), revealed that the final products with x, y?=?0.0, 0.3 and 0.4 exhibit superparamagnetic (SPM) behavior at room temperature, however the composition x, y?=?0.2 displays a ferromagnetic-like (FM) behavior. The saturation magnetization (Ms) reduces with rising the Li and Al contents. Compared to pristine CuFe2O4 spinel, the remanent magnetization (Mr), coercive field (Hc) and the magneto-crystalline anisotropy fields (Ha) improved for products synthesized with x, y?=?0.2 and then decrease for x, y?=?0.3 and 0.4. The squareness ratio Mr/Ms are less than 0.500, which suggest the single domain nanoparticles with uniaxial anisotropy for Li2xCu1–xAlyFe2-yO4 (0.0?? x, y???0.4) nanoparticles. The magneto-crystalline anisotropy constant (Keff) value is improved for Li0.8Cu0.6Al0.2Fe1.8O4 (i.e. x, y?=?0.2) magnetic nanoparticles and then decreased for higher Li and Al contents, due to the replacement of Cu and Fe ions with respectively Li and Al ions.
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    Tailored microstructures, optical and magnetic qualities of strontium hexaferrites: Consequence of Tm3+ and Tb3+ ions Co-substitution
    (Elsevier Sci Ltd, 2019) Almessiere, Munirah Abdullah; Slimani, Yassine; Tashkandi, Nabiha A.; Güngüneş, Hakan; Sertkol, Murat; Nawaz, Muhammad; Ercan, İsmail
    Terbium (Tb) and Thulium (Tm) co-doped strontium hexaferrites (SHFs), with composition SrFe12-2xTbxTmxO19 (0.00 <= x <= 0.04), were prepared via sol-gel auto-combustion method. The effect of Tb3+ and Tm3+ (as codopants) on SHFs were investigated in detail. XRD pattern of the prepared SHFs revealed the formation of M-type SHFs. A secondary phase of Fe2O3 starts to appear for x >= 0.02. The optical band gaps (E-g) of the prepared SHFs were widened with the increase in doping levels. Mossbauer study showed that the Tm3+ and Tb3+ ions have the preference to occupy 12k and 2a octahedral sites. M(H) measurements were recorded at room temperature (RT; T = 300 K) and low temperature (T = 10 K). The hysteresis loops of various SHFs revealed their ferrimagnetic (FM) nature at both RT and 10 K. Magnetic parameters including saturation magnetization (M-s), remanence (M-r), coercivity (H-c), squareness ratio (SQR = M-r/M-s) and magnetic moment (n(B)) were determined. Compared to the pristine (undoped) sample, lower content of Tm3+ and Tb3+ co-substitution (x = 0.01) improves significantly the magnetic properties of SHFs. With further increasing co-substitution contents (x > 0.01), an impurity phase appears and as a result the magnetization reduces. The observed SQR values of the proposed SHFs above 0.5 clearly indicated their single domain character with uniaxial magnetocrystalline anisotropy. Our systematic synthesis strategy and characterization may constitute a basis for achieving high quality co-doped SHFs in a customized way.
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    Tb3+ substituted strontium hexaferrites: Structural, magnetic and optical investigation and cation distribution
    (Chinese Society of Rare Earths, 2019) Almessiere, Munirah Abdullah; Slimani, Yassine; Güngüneş, Hakan; Sertkol, Murat; Nawaz, Muhammad; Algarou, N. A.; Baykal, Abdulhadi; Ercan, İsmail
    In this study, SrFe12?xTbxO19 (0.00 ? x ? 0.1) hexaferrites (HFs) were prepared successfully by citrate sol-gel approach. X-ray powder diffraction analyses affirm the hexagonal structure of products. Impurity phase starts to appear for x ? 0.04. The crystallites sizes were estimated to be in the range of 33–46 nm. All the products exhibit inhomogeneous distribution of grain size detected through SEM. The analyses of magnetization versus applied magnetic field, M(H), were performed. Magnetization measurements were done at room (300 K; RT) and low (10 K) temperatures. The different magnetic parameters including saturation magnetization Ms, remanence Mr, squareness ratio (SQR = Mr/Ms), coercivity Hc, and magnetic moment nB are deduced and discussed in detail. At both considered temperatures, M(H) results show ferrimagnetic nature for all compositions. It is shown that the Tb substitutions significantly affect M(H) data. A significant increase in the Ms, Mr, and nB is observed for x = 0.02 sample. The SQR values are around 0.5 indicating the single domain nature with uniaxial anisotropy. The obtained magnetic results were investigated deeply with relation to structural and microstructural properties. Mössbauer spectroscopy results were also investigated. According to Mössbauer results, the Tb3+ ions preferentially occupy 12k and 4f2 sites.
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    The Effect of Folic Acid- and Caffeic Acid-Functionalized SPION on Different Cancer Cell Lines
    (Springer New York LLC, 2018) Dönmez Güngüneş, Çiğdem; Alpsoy, Lokman; Baykal, Abdulhadi; Nawaz, Muhammad; Ülker Akal, Zeynep
    In this study, caffeic acid (CFA)- and folic acid (FA)-conjugated superparamagnetic iron oxide bio-nanocomposite (SPION@PEG-FA-@CFA) was prepared and its cytotoxic and apoptotic effects against murine fibroblast (L929), glioblastoma (U87), adenocarcinoma, human breast cancer (MCF-7), epithelioid cervix carcinoma (HeLa), and lung carcinoma (A549) have been determined. A real-time cell analyzer system (RTCA) for cytotoxicity, annexin assay and TUNEL, caspase 3/7 expression level, and caspase 3/7 activities for apoptosis were used. The RTCA showed that the cytotoxic effects of the bio-nanocomposite were higher in U87, MCF-7, and HeLa cells (which are folic acid-positive cells (FAR (+))). TUNEL, annexin, and caspase assay results indicated that the bio-nanocomposite caused apoptotic and necrotic impacts on cells. Necrotic and apoptotic cell ratios in FAR-positive cells (L929 and A549) were lesser than those in U87, MCF-7, and HeLa cells (FAR (+)). Therefore, the obtained results showed that the bio-nanocomposite can be used as a nano-medicine for biomedical application (cancer treatments). Moreover, this work can also be useful for designing other functionalized materials which could act as biomaterial. This study will be also informative for the researchers to design novel materials for biomedical applications. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.