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The desirable characteristics of Ba_6-3xNd_8+2xTi₁₈O₅₄ include high dielectric constant, low loss tangent, and high quality factor developed a new field for electronic applications. The microwave dielectric properties of Ba_6-3xNd_8+2xTi₁₈O₅₄, with x = 0.15 ceramics at different sintering temperatures (600–1300°C) were investigated. The phenomenon of polarization produced by the applied electric field was studied. The dielectric properties with respect to frequency from 1 MHz to 1.5 GHz were measured using Impedance Analyzer, and the results were compared and analyzed. The highest dielectric permittivity and lowest loss factor were defined among the samples. The complex dielectric modulus was evaluated from the measured parameters of dielectric measurement in the same frequency range, and used to differentiate the contribution of grain and grain boundary.

Ceramic samples of (Bi${}_{1-x}$Pb_x)NbO₄ ($x=0$, 0.025, 0.05, 0.10, 0.15, 0.20) with 0.75wt.% V₂O₅ addition sintered at 920${}^{\circ }$C, 940${}^{\circ }$C and 960${}^{\circ }$C are investigated. Pb is selected as a substitute for Bi${}^{3+}$ in BiNbO₄ ceramics as it exists in two stable valence states of $+$2 and $+$4 and the average valency matches to that of Bi${}^{3+}$. The average Shannon radius (for octahedral coordination) of Pb${}^{2+}$ (1.19Å) and Pb${}^{4+}$(0.775Å) cations is 0.9825Å, which is similar to that of Bi${}^{3+}$ ion (1.03Å). The dense ($>94$%) polycrystalline (Bi${}_{1-x}$Pb_x)NbO₄ samples fabricated mostly reveal orthorhombic (Pnna) phase ($\alpha$-BiNbO₄, Sp. Gp. 52) by powder XRD. Presence of satellite Pb₂Nb₂O₇ phase, the amount of which is increasing with increase in Pb content, is also noticed. The microwave dielectric constant (${\epsilon }_r^{\prime }$) values of the niobates are found to increase from 42 to 71, whereas the quality factor (Q_u.f) values are found to decrease from 5400 to 550 GHz with increasing substitution of Pb. The compositions so synthesized are important as hardly there are any microwave dielectric ceramics available with $45<{\epsilon }_r^{\prime }<75$.

Transparent ceramics have potential applications in various areas, including aerospace, relativistic optics industries, medical cares and defense. Specifically, they can be used as laser gain media, armor windows, IR domes, solid-state phosphors, scintillators and electro-optical components. From crystal structure point of view, transparent ceramic materials should have high crystallographic symmetries (cubic, tetragonal and hexagonal), which have minimal birefringent effect. Currently, transparent ceramics are dominantly based on oxide materials, although there are also nonoxides, such as fluorides and nitrides (oxynitrides). Transparent ceramics with pyrochlore and fluorite structures have attracted much attention in recent years, whereas fluorides are not well described in the open literature. Therefore, this paper is aimed to deliver an overview on the progress of the two categories of transparent ceramics, from material processing and characterization point of view.

BaTiO₃-based solid solutions involve high piezoelectric and ferroelectric properties. One of the most favorable systems of this material is Ba(Zr_xTi_1-x)O₃. While nano structured ceramics of which have a great potential for using them in capacitors, actuators, transducers and dielectrics to reach high K values. In this study, nano crystalline Ba(Zr_xTi_1-x)O₃(x=0.1-0.8) which is called BZT composite has been prepared by mechanical alloying. The parameters affecting the process and properties were evaluated. The starting powders that are used here were nano sized high pure ZrO₂; submicron sized high pure TiO₂ and BaCO₃. The prepared powder was calcined, compacted and sintered at different temperatures and in various times. The structural changes and phase developments during mechanical alloying were studied by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) and Transition Electron Microscopy (TEM). The results showed that by using mechanical alloying method, high dense nano crystalline BZT ceramics were obtained successfully at very low sintering temperature. The dielectric constant of BZT was much great, because of using nano materials in this method at the temperatures of 1250-1400°C. The effect of high energy milling in micro structural development of nano crystalline BZT has been discussed as well as dielectric properties.

In this study, mechanical alloying (MA) of Fe-50Al, Fe-49.5Al-1B, and Fe-47.5Al-5B (at.%) alloy powders and mechanical properties of sintered products of the as-milled powders were investigated. X-ray diffraction (XRD) results showed the addition of B caused more crystallite refinement compared to the B-free powders. To consider the sintering and ordering behaviors of the parts produced from cold compaction of the powders milled for 80 h, sintering was conducted at various temperatures. It was found that the sintering temperature has no meaningful effect on the long-range order parameter. The transformation of the disordered solid solution developed by MA to ordered Fe-Al- (B) intermetallics was a consequence of sintering. Also, the nano-scale structure of the samples was retained even after sintering. The microhardness of pore-free zones of the nanostructured specimens decreased by increasing the sintering temperature. Moreover, the sintering temperature has no effect on the compressive yield stress. However, the fracture strain increased by increasing the sintering temperature. The samples containing 1 at.% B showed more strain to fracture compared with the B-free and 5 at.% B samples.

Lightweight materials of Aluminum-Silicon P/M alloys offer the advantage of high-wear resistance, high strength, good temperature resistance, and a low coefficient of thermal expansion. An A359 MMC alloy was mixed together with Alumix 231 in this research. Powders were compacted with compaction pressure up to 700 MPa. Particle size and compaction pressure influenced green density. Compacted powders were sintered in a tube furnace under a flowing nitrogen gas. Sintering temperature, heating rate and sintering time were verified to determine best sintering conditions of the alloys. Chemical composition also contributed to gain higher sintered density. Precipitation strengthening method was used to improve mechanical properties of this materials.T6 heat treatment was carried out to produce fine precipitates to impede movement of dislocation. The chemical composition of this materials allow for the potential formation of several strengthening precipitates including θ (Al₂Cu) and β (Mg₂Si).