Mineral chabazite has shown the unusual ability to surface template nanometal particles, especially Ag. A chabazite analog was synthesized from delaminated metakaolin. The chabazite formed retained the platy morphology of the base clay. This morphology is ideal for displaying surface-supported nanometal particles. The synthetic chabazite analog demonstrated the ability to form and support large concentrations of Ag nanoparticles, as observed in the related natural mineral. Due to greater Al content, the synthetic chabazite manifests significantly improved capacity for the formation of such Ag nanoparticles. As in the case of the mineral chabazite, surface Ag nanoparticles of high uniformity were observed in the range of 5–6 nm.

Nanocrystallites of pure and mixed ternary ferrites, NiFe2O4 (NiF), CuFe2O4 (CuF), CoFe2O4 (CoF), Ni0.5Cu0.5Fe2O4 (CuNiF), Ni0.5Co0.5Fe2O4 (NiCoF), and Cu0.5Co0.5Fe2O4 (CuCoF) were prepared using the auto-combustion method employing urea as a fuel. The obtained materials were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron miscroscopy (TEM), scanning electron microscopy (SEM), and BET techniques. The elemental composition of the prepared samples was checked by X-ray fluorescence (XRF) analysis. XRD indicated that the as-synthesized samples exhibit a pure spinel crystal structure. The samples have crystallite sizes ranged from 12 to 47 nm. SEM and TEM analyses showed almost spherical morphology for all ferrite particles. The M–H curves recorded using the VSM (vibrating sample magnetometer) technique showed ferromagnetic hysteresis loop for all the samples investigated. The ferrite samples were tested to be used as a supercapacitor electrode material. It is found that the measured specific capacitance of the ferrite electrodes increases according to CuCoF > NiCoF > CoF > NiCuF > CuF > NiF. The CuCoF sample showed the greatest specific capacitance of 220 F/g at discharging current density l of A/g with, an energy density of 34.72 Wh/kg and power density of 605 W/kg. The magnetic properties were also measured for the obtained nanoparticles.

Magneto polymer matrix composites (MPMC) is a new class of magnetic polymer materials which are being developed and under investigation as potential materials for tomorrow’s aircraft structures. It encompasses magnetic, particulate strengthening (dispersion strengthening) as well as fiber reinforcement/strengthening characteristics which are sought out to be utilized toward making efficient future aerospace composite materials. Various types of ferrites including barium, cobalt, iron, and strontium were explored for being used in making new composites. Here a comprehensive review of the synthesis, structure, properties, thermodynamics, surface chemistry, and phase transformations of individual ferrites and clusters of ferrites as fillers is presented. In particular a discussion about the rational control of the mechanical, physical, thermal, electrical, and magnetic properties of magneto polymer matrix composites through surface functionalization, modification, emulsification/compounding/blending, heat treatment (phase transformation and separation), and control of processing conditions (temperature, pressure and geometry of mold) is provided. These smart materials have a wide range of potential applications in medicine, drug delivery, bio imaging, bio marking, tissue engineering, electromagnetic interference (EMI) and electromagnetic force (EMF) shielding, and as competent materials for aerospace structural applications.

Nanosized Eu2+-doped AlN phosphor was successfully synthesized by a metal-organic precursor method for the first time. Aluminum and europium chlorides were simultaneously reacted with triethylamine in acetonitrile media to yield solid precipitates, which were transformed into nanosized AlN:Eu2+ phosphor powders upon calcination in an ammonia gas atmosphere. The possible reaction mechanism was proposed, which is in good agreement with the experimental results. The direct formation of Al–N bonds through a coordination reaction in solution is a key factor in the formation of well-crystallized AlN:Eu2+ grains at a moderately low temperature (1200 °C), which significantly suppresses abnormal grain growth and favors the formation of nanocrystalline (∼15 nm) particles with a homogeneous particle size distribution. Due to the homogeneous distribution of a relative high amount of Eu incorporation (2 wt%), the nanophosphors were effectively excited by UV light and featured an intense green emission band with a peak at 506 nm.

The impedance dependence of resonant tunneling diodes (RTDs) based on the GaAs/AlAs heterosystem is investigated in the range of 0.1–40 GHz. The analysis shows that the impedance of about 90% of unbiased RTDs is well described by an equivalent circuit (EC) consisting of parallel-connected resistance and capacitance and an additional resistance connected in series with this parallel combination. When a bias voltage is applied to these RTDs, one needs a “quantum” inductance LQ to describe the impedance behavior. We find the value of LQ and calculate the delay time of electrons in the quantum well (QW) of an RTD. The impedance of the rest 10% of the RTDs is well described by an EC that takes into account the recharge of localized electron states at the heterointerfaces of the active layers. Expressions for the cut-off frequencies that take into account the delay of electrons in the QW and the localized electron states at the heterointerfaces are derived. It is shown that the delay of electrons in the QW and localized electron states at the heterointerfaces may significantly reduce the cut-off frequency of RTDs.