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Advanced turbine engines require the application of thermal barrier coatings (TBCs) to provide still higher reliability, thermal insulation effect and longer lifetime under harsh operating conditions. TBCs with nanostructure proved to be promising to deliver the desired property and performance. To exploit full potentials of the current widely used yttria-partially-stabilized zirconia (YSZ), nano-sized YSZ powders were developed and used as the ceramic source material. By controlling the deposition processes, novel TBCs with outstanding nanostructure such as nano-sized grains and pores were produced by atmospheric plasma spray (APS) and electron beam physical vapor deposition (EB-PVD), respectively. The incorporated nanostructure in TBCs resulted in substantial increase in thermal barrier effect and their lifetime. The long-term microstructure stability of the nanocoating was also investigated.

Three various α-alumina nanopowders have been characterized and their behavior in dry uniaxial pressing followed by pressureless sintering in air investigated. Nearly full dense ceramic material has been obtained at no more than 1300°C and its grain size evaluated by scanning electron microscopy and X-ray line profile analysis as being about 200 nm. The most suitable powder for low temperature sintering was reported to be that consisting of aggregates strong enough to enable their dense packing during the die filling and early period of pressure rise but capable of being destroyed further at final stage of compaction. Several dense samples with grain size on the level of 100 nm and less have been shown to be available at 1150-1200°C if a proper molding technique would be developed.

A three-part tape-enhanced tube was used in the current hypothetical solar unit to save the most radiation possible. The three parts were joined at different angles ($\beta$). The parameters of the carrier base fluid after mixing with CuO nanopowder were calculated using a homogeneous model. By adjusting the range of Y${}^{+}$, multiple layers were used to precisely depict the behavior of flow close to the wall. The results show the components of irreversibility as bar charts, velocity contours, and exergy drop contours. The tape angle ($\beta$) and inlet velocity were thought to be the main driving forces. An evaluation of the accommodation’s validity using numerical data shows that it is sufficient. The wall temperature decreases by about 0.0257% as the nanofluid angle rises and more collisions with the wall take place. Xd falls off roughly 5.19% from 0^∘ to 45^∘ and 5.87% from 0^∘ to 90^∘ as the angle $\beta$ rises. As $\beta$ rises, the entropy of friction increases by 9.88%. The outer wall cools by about 0.87% and Xd falls by about 92.3% when $\beta =45^{\circ }$ and Re rises.

Pure ZnO and Zn_1-xMn_xO (x=0.02 and 0.06) nanopowders have been synthesized by sol–gel technique at low temperatures. XRD results indicated that the crystal structure is hexagonal and there is no secondary phase. The compositional characterization of Mn-doped samples was investigated by EDX spectra. The size and morphology of nanoparticles were obtained by SEM and TEM images. Optical constants such as refractive index and extinction coefficient were evaluated from transmittance spectrum in UV region. The optical band gap energy showed a red-shift from 3.22 eV to 3.14 eV for pure and Zn_0.94Mn_0.06O, respectively. The Curie temperature of Mn-doped ZnO samples were determined and at room temperature no ferromagnetism state was observed.

In this paper, we have comparatively studied the “electron spin resonance” (ESR) of SiO₂ nanoparticles before and after neutron irradiation. From the comparative analysis of samples at the full sweep (sweep 5000 G at center field of 3300 G) in the same system, amount of defects were found to increase. At the field line around 3350 G, we found the free electron $g$ species $(g=2.002)$ and determined that this situation is more sustainable than the other observed cases (the cases existing in values 2.5–3 and 3–5 of $g$-factor). Moreover, expanded section near $g=2.002$ repeated with a sweep of 100 G and at two power due to microwave saturation effects has been studied.

Using strontium–titanium salts precursor, nanopowders (STO-based-NPs) were successfully synthesized by controlled gel-combustion method. Citric and nitric acids in an optimum ratio were used as the fuel and oxidizer agents, respectively. After heat treatment at 850${}^{\circ }$C, the crystalline structure of the products was investigated by X-ray diffraction. The effects of Ba and Ag dopants on particle size distribution were discussed by transmission electron microscopy (TEM). The optical and dielectric parameters such as energy band gap $(E_g)$, real and imaginary parts of refractive index, dielectric function and energy loss function of nanopowders have been investigated by UV–Vis and FTIR spectra. The band gap of SrTiO₃ increased with increasing Ba, Ag and Ba–Ag. Different atomic radii of dopants are responsible for changing optical and dielectric parameters due to the altered orbital configuration of the lattice structure.

The use of artificial biomaterials has been acclaiming potential therapeutic scope in diverse clinical applications. This review started with the description of the basics of biomaterials, and desirable properties, which are the prerequisites to understand biomaterials. The orthopedic biomaterials, their classification and the importance of calcium phosphate (CaP) materials for hard-tissue applications were utterly discussed. Furthermore, among the various CaP biominerals, the importance of hydroxyapatite (HAP) and its synthesis techniques was comprehensively reviewed. The sol–gel route for the synthesis of HAP nanoparticles and deposition of coatings were systematically studied. Among the metallic substrates, Ti6Al4V alloy remained the focus of this study. Moreover, several film pre-preparation methods were also given due importance. The importance of other surface modification techniques, especially in the context of Ti6Al4V substrates, was also discussed. Among several coating techniques to deposit CaP coatings, special attention was paid to the spin and dip coating techniques. In addition to monolithic HAP coatings, reinforced and antimicrobial HAP coatings were also reviewed from broad perspectives. Therefore, this review provides an in-depth insight into the preparation and properties of apatitic nanoparticles and their coatings for orthopedic and dental applications.

We investigate the effects of calcination time and concentration of solution on the structure, as well as optical properties in ZnWO₄ nanopowder prepared by hydrothermal method. The prepared powder were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman scattering, optical absorption and photoluminescent spectroscopy (PL). It is shown that the grain size and morphology of ZnWO₄ nanopowder can be controlled by adjusting the reaction time as well as the concentration of the solution. The resultant sample is a pure phase of ZnWO₄ without any impurities. The result showed that the optical property of ZnWO₄ nanopowders depend on their grain size. The optical band gap becomes narrower as the reaction time or concentration of solution is increased. The improved PL properties of the ZnWO₄ crystallites can be obtained with the optimal concentration of the solution.

Lithium fluoride (LiF) nanopowders were prepared by trifluoroacetate-based sol–gel processing. In this work, lithium acetate dehydrate (LiAc ⋅ 2H₂O) and trifluoroacetic acid (TFA) was used as lithium and fluorine sources. The thermal behavior of initial gel was examined using differential thermal analysis (DTA). Effects of solvent (glacial acetic acid, absolute ethanol, and ethylene glycol), Li⁺ concentration (0.5, 1, and 2 mol/l) and decomposition temperature (200, 250, and 300°C) on synthesis of LiF nanopowders by sol–gel method were investigated. The results of LPSA, FE-SEM, and XRD showed that the growth of particles and aggregation can be controlled by changing above parameters. However, it is indicated that optimum conditions are; solvent as ethanol, Li ion concentration (0.5 mol/l), and decomposition temperature (300°C), respectively. Also, the addition of oleic acid as an organic additive made the final LiF particles finer and about 70–90 nm.