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In recent times, considerable attention has been given to examining the impact of micro/nanostructure on the thermoelectric characteristics of nonstoichiometric AgSbTe 2 . The present investigation employed direct melting of elements that produced p-type AgSbTe 2 with spontaneous nanostructuring due to cation ordering. The product predominantly features an Ag-deficient Ag 0.927 Sb 1.07 Te 2.005 phase with monoclinic Ag 2 Te nanoprecipitates and exhibits a degenerate semiconductor-like behavior with an energy band gap of 0.15 eV. A Seebeck coefficient of 251 μV K -1 and a power factor of 741 μW m -1 K -2 at near ambient temperature are attained with this composition. The variable range hopping (VRH) and linear magnetoresistance (LMR) confirmed that the low-temperature transport followed a VRH between the localized states. The composition also exhibited glass like thermal conductivity of 0.2 W m -1 K -1 arising from phonon scattering at all-scale hierarchical structures that led to a high ZT of 1.1 at room temperature. The direct melted ingots show a high relative density of ∼97%, Vickers hardness H v of ∼108.5 kgf mm -2 , and excellent thermal stability, making them an attractive choice for TEGs.

In the present investigation, we present the comparison of the structural, magnetic, magnetocaloric and magnetoresistance behavior of solid state and sol-gel derived La 0.7 Sr 0.3 MnO 3 . X-ray diffraction together with Rietveld refinement confirms the rhombohedral structure of the synthesised samples with the R 3̄ c space group. The ferromagnetic-to-paramagnetic transition temperature decreases from 360 K to 346 K for the nanocrystalline sample. The XPS measurements confirm the presence of Mn 3+ in the synthesised samples. Furthermore, the polycrystalline sample exhibits a considerable -Δ S M of 4.68 J kg -1 K -1 at 360 K for a field change of 50 kOe and a relative cooling power (RCP) of 205 J kg -1 . A -Δ S M of 1.14 J kg -1 . Critical exponent analysis has also been performed on both samples to establish the universality class. Both samples exhibit a distinct metal-to-insulator transition, which increases with grain size from 187 K to 334 K as a result of grain growth and decreased grain boundary. As the grain size increases, the resistivity decreases and shifts towards high temperatures with increasing magnetic fields. The itinerant electron model (IEO) which is based on the hopping of O 2p itinerant electrons has been used to explain the resistivity behaviour of the samples. It is found that the negative magnetoresistance also increases with a decrease in grain size where the highest %MR of 26% can be observed for the nanocrystalline sample. These results make La -1 was obtained for the nanocrystalline sample at 346 K with an RCP of 83 J kg -1 . Critical exponent analysis has also been performed on both samples to establish the universality class. Both samples exhibit a distinct metal-to-insulator transition, which increases with grain size from 187 K to 334 K as a result of grain growth and decreased grain boundary. As the grain size increases, the resistivity decreases and shifts towards high temperatures with increasing magnetic fields. The itinerant electron model (IEO) which is based on the hopping of O 2p itinerant electrons has been used to explain the resistivity behaviour of the samples. It is found that the negative magnetoresistance also increases with a decrease in grain size where the highest %MR of 26% can be observed for the nanocrystalline sample. These results make La 0.7 Sr 0.3 MnO 3 a suitable candidate for multifunctional applications.

A few thallium based layered chalcogenides of α-NaFeO 2 structure-type are known for their excellent thermoelectric properties and interesting topological insulator nature. TlScQ 2 belongs to this structural category. In the present work, we have studied the electronic structure, electrical and thermal transport properties and thermal stability of the title compounds within the temperature range 2-600 K. Density functional theory (DFT) predicts a metallic nature for TlScTe 2 and a semiconducting nature for TlScSe 2 . DFT calculations also show significant lowering of energies of frontier bands upon inclusion of spin-orbit coupling contribution in the calculation. The electronic structure also shows the simultaneous occurrence of holes and electron pockets for the telluride. Experiments reveal that the telluride shows a semi-metallic behaviour whereas the selenide is a semiconductor. The thermoelectric properties for both the materials were also investigated. Both these materials possess very low thermal conductivity which is an attractive feature for thermoelectrics. However, they lack thermal stability and decompose upon warming above room temperature, as evidenced from high temperature powder X-ray diffraction and thermal analysis.

We report on the observation of double transition - a first order and a second order transition in Gd 5 Si 2-x Co x Ge 2 with x = 0, 0.1, 0.2 and 0.4 with the appearance of short-range ferromagnetic correlations. The first order phase transition is due to a combined magnetostructural transition from monoclinic paramagnetic phase to orthorhombic ferromagnetic phase on cooling while the second order transition arises from an orthorhombic paramagnetic to ferromagnetic phase on cooling. Structural studies show that the substituted compounds crystallize in a combination of Gd 5 Si 2 Ge 2 and Gd 5 Si 4 phases. Low-temperature X-ray diffraction measurements confirm the complete transformation from monoclinic to orthorhombic phase. DC magnetization measurements reveal an anomalous low field magnetic behaviour indicating a Griffiths-like phase. This unusual behaviour is attributed to the local disorder within the crystallographic structure indicating the presence of short-range magnetic correlations and ferromagnetic clustering, which is stabilized and enhanced by competing intra-layer and inter-layer magnetic interactions. The magnetostructural transition results in entropy changes (-ΔS M ) of 9 J kg -1 K -1 at 260 K for x = 0.1, 8.5 J kg -1 K -1 at 245 K for x = 0.2 and 4.2 J kg -1 K -1 at 210 K for x = 0.4 for a field change of 50 kOe. Co substitution induces compelling crystallographic and magnetoresponsive effects in the Gd-Si-Ge system, which could be useful for potential and smart applications such as solid-state magnetic refrigeration and sensitive magnetic switching from paramagnetic to ferromagnetic state. Universal curve analysis has been carried out on the substituted samples to study the order of the magnetic transition.

The poor solubility, poor biocompatibility and disposal issues make fluorescent quantum dots such as CdSe, CdS, ZnS, InP, InAs, etc. impractical for imaging tissues or intercellular structures. As calcium phosphate is the main inorganic component of human bone and teeth, hydroxyapatite (Ca10(PO4)6(OH)2, HAp) is highly biocompatible and bioactive. Since HAp nanoparticles are not luminescent, a novel inorganic biocompatible fluorescent probe was suggested by doping HAp with lanthanides. Here we report the growth of chemically pure fluorescent HAp nanoparticles synthesized by a new methodology, liquid phase pulsed laser ablation using third harmonics (355 nm) of Nd-YAG laser. Europium doped HAp nanoparticles show emission with prominent peaks at 531 nm, 572 nm, 601 nm and 627 nm upon excitation at a wavelength of 325 nm. The red luminescence could also be observed under visible excitation at 459 nm and is suitable for living cell applications.