Ni0.5Zn0.5Fe2O4-dispersed In2O3-spotted ZnO nanoparticles: Ammonia-source and surface and photocatalytic properties

Ammonia-source, used to attain the desired pH during synthesis, is conceived to influence the physical characteristics of ZnO-based nanomaterials, and the catalytic activity is susceptible to surface characteristics of semiconductor–photocatalyst. In this context, Ni_0.5Zn_0.5Fe₂O₄-dispersed In₂O₃-spotted ZnO nanoparticles have been obtained by using either tetramethyl ammonium hydroxide or ammonium carbonate as ammonia-source at identical pH (9) using identical quantities of the precursors following identical synthetic procedure. The nanoparticles have been characterized using energy dispersive X-ray spectroscopy, elemental mapping, selected area electron and X-ray diffractometries, transmission electron microscopy, etc. The nanoparticles obtained using ammonium carbonate possess larger (1) pore width, (2) pore volume, and (3) surface area compared with nanoparticles prepared employing tetramethyl ammonium hydroxide. Although the electrical properties of both the samples do not differ remarkably, the violet light-absorption of the sample prepared using the carbonate is slightly larger than that of the other sample. Further, the In₂O₃-spotting is slightly larger on using ammonium carbonate than using tetramethyl ammonium hydroxide. To degrade dye under visible light, the sample obtained using ammonium carbonate shows larger catalytic activity compared with nanoparticles prepared using tetramethyl ammonium hydroxide. The observed photocatalytic activities are explained based on the surface characteristics.     

Copper‐substituted spinel Zn‐Mg ferrite nanoparticles as potential heating agents for hyperthermia

Cu_xZn_0.5‐xMg_0.5Fe₂O₄ (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) ferrite nanoparticles are synthesized via thermal treatment technique using polyvinyl alcohol (PVA) as a capping agent. The effect of Cu²⁺ ions substitution on the magnetic and structural properties of ZnMg ferrite nanoparticles is assessed. X‐ray diffraction (XRD) results prove the formation of spinel cubic ferrite with nanocrystalline structure. It is observed by increasing Cu²⁺ ions content in Cu²⁺‐substituted ZnMg ferrite samples, the lattice constant decreases. The field‐emission scanning electron microscopy (FESEM) micrographs indicate that all samples have sizes in nanometer scale with almost spherical morphology and ZnMg ferrite nanoparticles size is increased as the result of Cu²⁺ substitution. Magnetic data show that by increasing in Cu²⁺ content, the saturation magnetization (Ms) increases up to x = 0.3 and then declines with the addition of more Cu²⁺ ions in the samples. To assess the heat release of Cu²⁺‐substituted ZnMg ferrite nanoparticles, an alternating magnetic (AC) field is applied. The results show an upward trend for the samples in the temperature vs time chart, as a result of increasing in Ms of the samples. The Cu_0.3Zn_0.2Mg_0.5Fe₂O₄ sample exhibits a temperature increase up to 43°C during 510 seconds in the exposure of 125 Oe magnetic field intensity. The cell compatibility of the samples is investigated using osteoblast‐like cells (MG63). Results show that the substitution of Cu²⁺ significantly affects the cell compatibility of the ZnMg ferrite nanoparticles.     

Fe3O4@SiO2@IPDI-HEA改性水性有机硅聚氨酯光固化膜的性能

以Fe_3O_4纳米粒子为核、丙烯酸酯为壳,通过溶剂热法制备了Fe_3O_4@SiO_2@IPDI-HEA纳米粒子。通过IR、TEM和XRD对其结构进行了表征,通过光差热扫描(photo-DSC)和TGA考察了该纳米粒子对水性有机硅聚氨酯光固化体系性能的影响。结果表明:Fe_3O_4@SiO_2@IPDI-HEA粒子的加入,对体系的光聚合性能没有明显影响,但可明显提高固化膜的耐热性和拉伸强度,当Fe_3O_4@SiO_2@IPDI-HEA的质量分数为1.5%时,固化膜的初始分解温度(T5%)增加了21.9℃,拉伸强度增加了6.9MPa。并且,Fe_3O_4@SiO_2@IPDI-HEA可以赋予光固化膜一定的电磁性能,当频率在0～(1×10~7) Hz内时,其介电常数均在4以上。     

碳包覆铁酸镍锂纳米晶体的制备

以金属离子的柠檬酸盐为前驱体,通过溶胶－凝胶和水热法相结合的方法,制备碳包覆的铁酸镍锂（ C－LiNi0．5 Fe2 O4）晶体。采用DSC－TG、 XRD、 SEM等技术对其结构进行研究。结构表明,样品粒径均匀,无团聚现象。     

Enhancement of magnetic properties of Ni0.5Zn0.5Fe2O4 nanoparticles prepared by the co-precipitation method

Nano crystalline Ni–Zn ferrites of composition Ni_0.5Zn_0.5Fe₂O₄have been prepared by a chemical co-precipitation method. The powdered samples were sintered at a temperature of 800 °C and 900 °C for three hours. X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Fourier Transform Infrared (FTIR) Spectroscopy were used to study their structural and morphological changes. The enhanced magnetic properties were investigated by using a Vibrating Sample Magnetometer (VSM). The saturation magnetization was found to increase from 73.88 to 89.50 emu/g as a function of sintering temperature making this material useful for high frequency applications. Electromagnetic studies showed sustained values of permittivity up to 1 GHz. These results have been explained on the basis of various models and theories.     

Low temperature sintering of laminated Ni0.5Ti0.5NbO4-Ni0.8Zn0.2Fe2O4 composites for high frequency applications

The laminated magneto-dielectric composites of Ni_0.5Ti_0.5NbO₄(NTN)-Ni_0.8Zn_0.2Fe₂O₄(NZO) were prepared by the conventional solid-state sintering method. The phase composition, microstructure, dielectric and magnetic properties of the composites were investigated. The results show that the as-prepared composites are very dense and the NTN and NZO phases can coexist in the composites without any secondary phase. The as-prepared composites also exhibit excellent dielectric and magnetic properties in the frequency range from 10 MHz to 1 GHz, which make them have potential applications for high-frequency electronic devices.     

Processing and characterization of nano-magnetic Co0.5Ni0.5Fe2O4 system

Various techniques such as X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron micrographs (SEM), energy dispersive X-ray (EDX) and a vibrating sample magnetometer (VSM) were used to investigate the structural, morphological, and magnetic properties of spinel Co_0.5Ni_0.5Fe₂O₄ system. XRD and IR analyses enabled us to determine the functional group and structural parameters of Co_0.5Ni_0.5Fe₂O₄. EDX measurements showed the concentrations of O, Ni, Fe, and Co species involved in Co_0.5Ni_0.5Fe₂O₄ specimen from the uppermost surface to the bulk layers. The magnetization and coercivity of the as synthesized composite were 77 emu/g and 128 Oe, respectively.     

纳米复合材料Co0.5Ni0.5Fe2O4-SiO2的显微结构和磁性

采用溶胶-凝胶法制备了Co0.5Ni0.5Fe2O4-SiO2纳米复合材料.利用热重-差热分析表征了热处理过程中干凝胶的变化.用X射线衍射、透射电镜、振动样品磁强计和M(o)ssbauer效应研究了样品的结构、晶粒尺寸和磁性.结果表明:经900℃热处理后,形成了分布均匀的Co0.5Ni0.5Fe2O4-SiO2纳米复合材料,其中Co0.5Ni0.5Fe2O4-SiO2的晶粒尺寸为20 nm.随热处理温度的升高,样品的晶粒尺寸、比饱和磁化强度以及矫顽力均变大,并从超顺磁和磁有序的混合状态转变为完全的磁有序状态.     

A critical review of bioceramics for magnetic hyperthermia

Magnetic hyperthermia (HT) using biocompatible ceramics is a ground-breaking, competent, and safe thermo-therapeutic strategy for cancer treatment. The magnetic properties of bioceramics, along with their structure and synthesis parameters, are responsible for the controlled heating of malignant tumors and are the key to clinical success. After providing a brief overview of magnetism and its significance in biomedicine, this review deals with materials selection and synthesis methods of bioceramics/glasses used for HT. Relevant research carried out on promising bioceramics for magnetic HT, with a focus on their size, shape, surface functionalization, magnetic field parameters, and in vitro/in vivo properties to optimize cancer therapy, is also discussed. Recent progress in magnetic HT combined with chemotherapy and phototherapy is especially highlighted, with the aim to provide interdisciplinary knowledge to advance further the applications of bioceramics in this field.     

Biocompatible PEGylated Fe3O4 Nanoparticles as Photothermal Agents for Near-Infrared Light Modulated Cancer Therapy

In accordance with the World Cancer Report, cancer has become the leading cause of mortality worldwide, and various therapeutic strategies have been developed at the same time. In the present study, biocompatible magnetic nanoparticles were designed and synthesized as high-performance photothermal agents for near-infrared light mediated cancer therapy in vitro. Via a facile one-pot solvothermal method, well-defined PEGylated magnetic nanoparticles (PEG–Fe₃O₄) were prepared with cheap inhesion as a first step. Due to the successful coating of PEG molecules on the surface of PEG–Fe₃O₄, these nanoparticles exhibited excellent dispersibility and dissolvability in physiological condition. Cytotoxicity based on MTT assays indicated these nanoparticles revealed high biocompatibility and low toxicity towards both Hela cells and C6 cells. After near-infrared (NIR) laser irradiation, the viabilities of C6 cells were effectively suppressed when incubated with the NIR laser activated PEG–Fe₃O₄. In addition, detailed photothermal anti-cancer efficacy was evaluated via visual microscope images, demonstrating that our PEG–Fe₃O₄ were promising for photothermal therapy of cancer cells.     

Ni0.5 Fe2.5 O4/ZrO2磁性纳米固体酸的合成与表征

将磁性基质Ni0.5Fe5O4／ZrO2和ZrO2进行组装制备出磁性固体酸催化剂，采用TEM、DTA、XRD等手段对Ni0.5Fe5O4／ZrO2磁性固体酸催化剂的结构和性能进行表征，结果表明磁性基质的引入延迟了ZrO2的晶化以及ZrO2(t)相向ZrO2(m)相的转变，使ZrO2更加稳定．     

Intensification of levofloxacin sono-degradation in a US/H2O2 system with Fe3O4 magnetic nanoparticles

Fe3O4 magnetic nanoparticles (MNPs) were synthesised, characterised, and used as a peroxidase mimetic to ac-celerate levofloxacin sono-degradation in an ultrasound (US)/H2O2 system. The Fe3O4 MNPs were in nanometre scale with an average diameter of approximately 12 to 18 nm. The introduction of Fe3O4 MNPs increased levofloxacin sono-degradation in the US/H2O2 system. Experimental parameters, such as Fe3O4 MNP dose, initial solution pH, and H2O2 concentration, were investigated by a one-factor-at-a-time approach. The results showed that Fe3O4 MNPs enhanced levofloxacin removal in the pH range from 4.0 to 9.0. Levofloxacin removal ratio in-creased with Fe3O4 MNP dose up to 1.0 g·L?1 and with H2O2 concentration until reaching the maximum. More-over, three main intermediate compounds were identified by HPLC with electrospray ionisation tandem mass spectrometry, and a possible degradation pathway was proposed. This study suggests that combination of H2O2, Fe3O4 MNPs and US is a good way to improve the degradation efficiency of antibiotics.     

Magnetoelectric effect of Ni0.8Zn0.2Fe2O4/Sr0.5Ba0.5Nb2O6 composites

Novel magnetoelectric composites were prepared by incorporating the dispersed Ni_0.8Zn_0.2Fe₂O₄ ferromagnetic particles into Sr_0.5Ba_0.5Nb₂O₆ relaxor ferroelectric matrix. Dense composite ceramics were obtained with the co-presence of Sr_0.5Ba_0.5Nb₂O₆ and Ni_0.8Zn_0.2Fe₂O₄, and they could be electrically and magnetically poled to exhibit a significant magnetoelectric effect. A maximum magnetoelectric voltage coefficient of 26.6 mV/cm/Oe was observed from the composites with 70 mol% Sr_0.5Ba_0.5Nb₂O₆, which was much greater than that of magnetoelectric compounds and solid solutions. It is convenient to use the Pb-free (Sr,Ba)Nb₂O₆ relaxor as the matrix for ferromagnetic/ferroelectric composites in the future development of magnetoelectric materials.     

BaTiO_3/Ni_(0.5)Zn_(0.5)Fe_2O_4复相陶瓷的制备及其性能

采用溶胶–凝胶工艺制备了一种渗流型多铁性BaTiO3/Ni0.5Zn0.5Fe2O4(BT/NZF)复相陶瓷。研究了烧结温度和组成对BT/NZF复相陶瓷的致密化和显微结构形成过程的影响,并研究了复相陶瓷的组成与其性能的变化关系。结果表明:在1200～1300℃范围内不同温度热处理12h,0.1BT/0.9NZF(体积分数)复相陶瓷的介电常数达到14000～31000,远高于纯BT陶瓷的介电常数;磁导率达140,接近于纯NZF陶瓷的磁导率。提高烧结温度有利于陶瓷的密度和介电常数的进一步提高;增加铁氧体含量有利于获得铁氧体晶粒尺寸大和磁导率高的复相陶瓷。     

La掺杂Ni0.5Zn0.5FeO4铁氧体的制备与微波吸收性能

采用高分子凝胶法制各了Ni0.5Zn0.5LaxFe2-xO4(x=0,0.05,0.1)铁氧体,采用XRD,TEM和HP8510网络分析仪对其结构、形貌、电磁和微波吸收性能进行了研究.结果表明,当煅烧温度为600℃时,立方晶系尖晶石结构的Ni0.5Zn0.5La0.05Fe1.95O4相初步形成,La在尖晶石结构中固溶量有限.与Ni0.5Zn0.5Fe2O4铁氧体相比,掺杂La的Ni-Zn铁氧体的tanδm值降低,tanδε滥升高.与Ni0.5Zn0.5Fe2O4铁氧体相比,x=0.1样品的吸波性能降低,而x=0.05样品的吸波性能提高,其电磁波反射率小于-10 dB的频宽可达2.7 GHz,最小反射率为-15.6 dB.     

Preparation of multiferroic composites of BaTiO3–Ni0.5Zn0.5Fe2O4 ceramics

Magneto-electric coupling in ceramic composites formed by ferroelectric and ferromagnetic phases can be obtained via an adequate mechanical coupling between the individual piezoelectric and magnetostrictive phases (product property). In the present work, the possibility of forming diphase ferroelectric–ferromagnetic ceramics has been investigated. Composites of xBaTiO₃–(1 − x)Ni_0.5Zn_0.5Fe₂O₄ with x = 0.5, 0.6 and 0.7 were prepared according two different procedures: (i) by direct mixing powders of perovskite BaTiO₃ and Ni_0.5Zn_0.5Fe₂O₄ spinel prepared by solid state and (ii) by coprecipitating Fe^III–Ni^II–Zn^II nitric salts in a NaOH solution in which the BaTiO₃ powders were previously dispersed. Optimum processing parameters for good homogeneity, densification and for a reduction of the chemical reactions at the interfaces ferroelectric-ferrite were found. A temperature and composition-dependent magnetic order is present in all the composites, with a dilution effect of the magnetisation due to the presence of the non-ferromagnetic phase. A diffuse ferroelectric–paraelectric transition due to the BaTiO₃ phase was identified by the temperature-dependence of the permittivity and losses, showing that at room temperature the material preserves a ferroelectric order. The interfaces play important roles in the dielectric properties, causing space charge effects and Maxwell–Wagner relaxation, particularly at low frequencies and high temperatures. The combined ferroelectric and magnetic ordering will result in magneto-electric coupling in this material; further investigations are necessary.     

Effects of hydrothermal process parameters on the physical,magnetic and thermal properties of Zn0.3Fe2.7O4 nanoparticles for magnetic hyperthermia applications

Effects of hydrothermal temperature and time on physical, magnetic and thermal properties of Zn-substituted magnetite nanoparticles (Zn_0.3Fe_2.7O₄) were assessed. The magnetic nanoparticles were synthesized via citric acid-assisted hydrothermal reduction route at temperatures of 150, 175 and 200 °C for duration of 10, 15 and 20 h. The nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and specific loss power (SLP) measurements. The results showed that temperature and time of the hydrothermal process both had significant effects on nanoparticles composition and properties. It was observed that at 150 °C, heat generation was insufficient to produce activation energy required for nucleation of Zn_0.3Fe_2.7O₄ spinel nanoparticles, even after a long time. At 175 °C, although temperature was low, but the suitable condition for nucleation of nanoparticles was made and spinel nanoparticles with the size of about 13 nm were formed after 15 h. Nonetheless, since crystallinity and SLP of the nanoparticles was low, they showed weak performance for magnetic hyperthermia. At 200 °C, the required activation energy was provided for nanoparticles nucleation; however, the spinel was oxidized to hematite, resulting in a decrease in thermal and magnetic properties. In overall, the nanoparticles synthesized at 200 °C for 15 h possessed the best characteristics of reasonable purity, saturation magnetization of about 35.9 emu/g and SLP of 18.7 W/g.     

Fe3O4/poly(acrylic acid) hybrid nanoparticles for water‐based drilling fluids

Because of the sizes of the pore throat are on the nanometer scale, nanoparticles with sizes on the nanoscale have been developed as candidates for plugging materials during drilling in shale formation. In this study, Fe₃O₄ nanoparticles were prepared by a coprecipitation method, and then, Fe₃O₄/poly(acrylic acid) (PAA) hybrid nanoparticles were obtained through the modification of the Fe₃O₄ nanoparticles with PAA. The hybrid nanoparticles were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and thermogravimetric analysis. The magnetic properties, salt tolerance, and compatibility with sulfomethylated phenolic resin of the nanoparticles were studied. The plugging properties of the Fe₃O₄/PAA hybrid nanoparticles were evaluated by filtration testing of the filter cakes at ambient temperature and 80 °C. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43967.     

Comparative Study of Silver Nanoparticles Coated and Uncoated NiO–Fe2O3–CaO–SiO2–P2O5 Ferromagnetic Bioactive Ceramics

Bioactive ferromagnetic ceramics of system xNiO–(3?x)Fe₂O₃–52CaO–30SiO₂–15P₂O₅, (x = 0, 3 mol%) have been prepared in the laboratory using sol–gel technique. Silver nanoparticles coating has been undertaken on the surface of synthesized samples. Comparative study of silver nanoparticles coated and uncoated samples has been undertaken with the help of transmission electron microscopy, X‐ray diffraction (XRD), degradation, drug delivery, hemolysis, antimicrobial, and cell culture studies. XRD patterns indicate the growth of hydroxyl apatite layer on the surface of coated as well as uncoated samples. Ferromagnetic properties of samples have been investigated with the help of vibrating sample magnetometer technique. Samples have shown good response as drug carriers under normal conditions as well as under the influence of magnetic field. Drug release mechanism and mesoporus nature of samples have been investigated with the help of Brunauer–Emmett–Teller technique. Nonreactivity of samples (coated and uncoated) with red blood cells and white blood cells show nontoxic nature of the samples. Coated samples have shown better antimicrobial properties against six different microorganisms, including some resistive strain like methicillin‐resistant Staphylococcus aureus with minimum inhibitory concentration of 0.05 mg/ml as compared to uncoated samples. It has been observed that samples also provide a healthy environment for the growth of MG 63 cell lines. It has been noticed that presence of silver nanoparticles on the surface of samples improve degradation and antimicrobial properties.