The crystal structure and microwave dielectric properties of apatite‐type LiRE9(SiO4)6O2 ceramics (RE = La, Pr, Nd, Sm, Eu, Gd, and Er) have been investigated. The densification of lithium apatites has been greatly improved with the addition of 1 wt% LiF. Selected area electron diffraction and X‐ray diffraction (XRD) Rietveld analysis confirm that these compounds belong to the P63/m (No. 176) space group with hexagonal crystal symmetry. The porosity‐corrected relative permittivity was found to decrease with decreasing ionic polarizability of RE3+ ions. Relationships between the structural parameters and microwave dielectric properties have been examined. The observed variation in the quality factor of LiRE9(SiO4)6O2 + 1 wt% LiF ceramics (RE = La, Pr, and Nd) was correlated with average cation covalency (%). The temperature coefficient of resonant frequency was found to depend on the bond valence sum of cations. LiEr9(SiO4)6O2 + 1 wt% LiF ceramics showed good microwave dielectric properties with εr = 12.8, Qu × f = 13000 GHz and τf = +17 ppm/°C. All the compositions showed low coefficient of thermal expansion with thermal conductivity in the range 1.3–2.8 W (m K)−1.

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Recently, two-dimensional layered semiconductors caught attention due to their tuneable thickness dependent properties and its optoelectronic device applications. This paper reports the effect of annealing temperature and annealing duration on structural, compositional and optical properties of tin disulphide thin films (SnS2) fabricated using a bi- stage process. The process involves thermal evaporation of metallic tin precursor films and post sulphur annealing process in a non-vacuum furnace. The annealing temperatures ranged from 300 °C to 500 °C while annealing time varied from 0.5 to 3 hours. The annealing at 300°C improved the crystallinity of SnS2 thin films. Raman analysis showed a prominent peak at 207 cm−1, while at higher temperatures nanocrystalline SnS2 phase is observed. Optical bandgap got reduced as annealing temperature increased and at 300°C, the bandgap was 2.7 eV. The above obtained properties of SnS2 opens a pathway for using these films for potential applications.

In the present study, we report the growth of silver nanoparticles in SiO 2 matrix by co-sputtering technique. The effect of deposition conditions on the formation of Ag nanoparticles were systematically studied using scanning electron microscopy (SEM), UV-Vis absorption studies. The optical absorptive nonlinearity of the nanoparticles was studied by using open aperture Z-scan techniques. The surface plasmon peak in the absorption spectra indicates the presence of Ag nanoparticles in the matrix. The open aperture Z-scan studies shows the Ag-SiO 2 nanocomposites can be used as a good optical limiter.

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