Investigation of thallium-doped Bi2Se3 nanoparticles: structural, optical and transport properties

The properties such as structural, mechanical, electronic structure, magnetic, optical and transport properties of the half-Heusler alloys of Rhodium RhFeZ(Z = P, As, Sb, Sn, Si, Ge, Ga, In, Al) are investigated at normal pressure. The alloys RhFeSb, RhFeSn, RhFeGe, RhFeGa, RhFeIn and RhFeAl are more stable in γ-phase. But the alloys RhFeP, RhFeAs and RhFeSi exhibit stability in β-phase under normal pressure. Among the investigated alloys, RhFeSn and RhFeGe are half-metallic at normal pressure. All the other half-Heusler alloys, RhFeP, RhFeAs, RhFeSb, RhFeSi, RhFeGa, RhFeIn and RhFeAl are ferromagnetic at normal pressure. To understand the transport properties, Seebeck coefficients, electrical conductivity, thermal conductivity and power factor are examined. The investigation infers that the alloys RhFeSn and RhFeGe possess remarkable transport properties and find potential applications in thermoelectric devices.

Tellurium (Te) doped bismuth selenide (Bi2Se3−xTex) nanosheets have been successfully synthesized by the microwave-assisted method in the presence of ethylene glycol (EG). The obtained products were characterized by powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected-area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy techniques. The electrical transport properties of the nanosheets are investigated by measuring the electrical conductivity and the Seebeck coefficient at temperatures ranging from 298 to 523 K. The power factor values of the Bi2Se3−xTex nanosheet vary with different doping concentrations of Te, and the maximum power factor can reach 178 μW m−1 K−2 at 523 K for Bi2Se2.7Te0.3, indicating the potential application in thermoelectric devices.

First-principles calculations to investigate electronic, optical, and thermoelectric properties of Na2GeX3 (X = S, Se, Te) for energy applications

A series of zinc doped cobalt chromium ferrite Co1-xZnxFe1.5Cr0.5O4 (where 0 £ x £ 1) were synthesized by co-precipitation technique. Structural, optical, transport and magnetic properties were characterized by X-ray diffraction (XRD), diffuse reflectance, AC electrical properties and hysteresis loop. XRD analysis indicates that all samples consist of a single-phase cubic spinel structure. Rietveld refinement results indicated an increase in lattice parameter due to the replacement of Co2+ by Zn2+ and migration of Fe3+ ions from A-site to B-site. Optical energy band gaps were calculated and it was found that both Eg1 and Eg2 increase with increasing Zn content. Dielectric constant έ, έ', and dielectric loss tangent tanδ were measured at room temperature as a function of applied frequency and temperature. It was noticed, that έ and έ' increase with temperature increment and decrease with increasing frequency and this anomaly can be explained by Maxwell Wagner two-layer model. Magnetic measurements revealed that the saturation magnetization increases as Zn content increases up to Zn=0.4 and after that, the saturation magnetization decreases.

Unveiling the thermoelectric, optical and mechanical performances of Hafnium and Zirconium based Beryllium oxide perovskite

Influence of silane flow on structural, optical and electrical properties of a-Si:H thin films deposited by hot wire chemical vapor deposition (HW-CVD) technique

The nanoStructured ZnO thin films were prepared by Spin coating technique on glass substrates at various layers. The structural and optical properties were characterized by field emission scanning electron microscopy (FESEM) and UV-Vis-NIR respectively. The surface morphology reveals that the nanostructured ZnO thin films become densely packed as the thickness increased. The average particles size of ZnO thin film estimated from FESEM images at different layers of 1, 3, 5, 7, 9 were 20nm, 28nm, 36nm, 39nm and 56nm, respectively. The surface roughness of thin films was increase as the thin film thickness increases. The results show all films are transparent in the visible region (400-800 nm) with average transmittance above 85 %. Meanwhile, the optical band gap was decrease as the film thickness increases. The conductivity of ZnO thin film slightly improved as the thickness increased as measured through two probes 1-V measurement system.

Bismuth Selenide (Bi2Se[Formula: see text] has a wide range of applications in thermoelectric devices. In this regard, Bi[Formula: see text]Tl[Formula: see text]Se3 nanoparticles were synthesized using a hydrothermal method and their structural and optical properties were studied using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and diffuse reflectance spectroscopy (DRS). The crystal structure and the other lattice parameters including strain ([Formula: see text] and average crystallite size ([Formula: see text] were determined through XRD analysis. The average crystallite size and strain of the developed nanoparticles were calculated to be 20.33[Formula: see text]nm and [Formula: see text], respectively. FTIR confirmed the presence of Bi–Se stretching modes at 438 and 524[Formula: see text]cm[Formula: see text]. The band gap of the nanomaterial was derived using DRS characterization. Transport properties were examined in the temperature range of room temperature to 430[Formula: see text]K. These findings provide insight into their potential for future applications in thermoelectric technologies.

Exploring the ultra-low lattice thermal conductivity of a two-dimensional compound Tl2Se3

Structural, morphological and optical properties of barium doped bismuth ferrite thin films deposited by spray pyrolysis

Highly transparent conducting and enhanced near-band edge emission of SnO2:Ba thin films and its structural, linear and nonlinear optical properties

In this thesis, low temperature (RT) zinc oxide (ZnO) films were directly grown on (01-12)sapphire substrates at 300oC by atomic layer deposition (ALD) using diethylzinc (DEZn) and nitrous oxide (N2O). Influences of post-annealing parameters including annealing temperature, annealing time interval and annealing atmosphere on the properties of post-annealing ZnO films were investigated. The structural, optical and transport properties of the post-annealing ZnO films were characterized by θ-to-2θ X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Hall measurements, photoluminescence spectroscopy (PL) and atomic force microscopy (AFM). Based on the XRD results, ZnO films were found to show c-axis preferred orientation. It was found that the transport and structural properties of the ZnO post-annealed films were highly influenced by annealing atmosphere. The most significant improvement in structural and transport properties were obtained for the ZnO film annealed in in N2 atmosphere at 900 oC for 10min. Under the optimum annealing condition, high transparency (~87%), low resistivity of 1.12x10-2 Ω∙cm and high mobility of 17.20 cm2/Vs were achieved in the ZnO films.

The effective role of potassium doping in improving the structural, morphological optical, and electrical properties of CdO thin film for optoelectronic application

Nickel foam of various pore-size coated graphene thin film of 200 nm thickness was investigated as a function of the pore size. The structural properties were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The optical properties were analyzed through the UV–Visible reflectance and Photoluminescence spectra. Hall Effect and Electrochemical impedance spectroscopy techniques were used to study the electrical and dielectric properties. The thermal properties were measured through the photothermal deflection technique. By decreasing the pore size, the electrical conductivity was increased from 9.42 × 107 to 33.26 × 107 S m−1, volume and surface carrier densities were decreased from −8.66 × 1021 to −2.05 × 1021 cm−3 and from −1.13 × 1014 cm−2 to −0.41 × 1014 cm−2; respectively, the specific capacitance was increased from 15.52 × 106 F to 19.65 × 106 F and the dielectric permittivity of value in the order of 1.5 × 103 F m−1 was decreased with the frequency. It was developed the photothermal deflection technique and discussed its sensitivity to the determination of thermal properties which show that the thermal conductivity decreased from 4.12 to 3.58 W m−1 K−1 and the thermal diffusivity decreased from 0.146 to 0.109 cm2 s−1. It was established semi-empirical relationships which allow to deduce the thermal properties and optical band gap without needing to measure them. These results introduce the graphene coated on Nickel foam sheets as good candidate for potential use in photoelectric and thermoelectric devices.

Effects of ammonia in the synthesis of copper (II) oxide nanostructures grown via microwave chemical bath deposition