Hafnium Oxide and Hydrogen Co-Doped Indium Oxide Films Deposited by Magnetron Sputtering Technology

Hafnium and Hydrogen co-doped indium oxide films (IHFO:H) were prepared by radio frequency magnetron sputtering technology. The effect of hydrogen-donor dopant on the structural, optical and electrical properties of the films was investigated systematically. The resistivity of the IHFO:H film decreased by 2.4×10-4 Ω cm and the mobility improved by 8.2 cm2/Vs compared with Hafnium oxide doped indium oxide film. Employing the IHFO:H film as an electrode for a solar cell can improve efficiency.

Comparison of strain and ferroelectric properties of La,Nb and Li,Nb co-modified BNKT–ST ceramics

A comparison between the influence of concurrent A and B-site acceptor-donor (Li,Nb) and donor-donor (La,Nb) doping in Pb-free Bi 0.5 (Na 0.84 K 0.16 ) 0.5 TiO 3 –SrTiO 3 piezoelectrics on structure, ferroelectric and high voltage induced strain were made. In this work, Lithium was chosen as acceptor and Lanthanum was chosen as donor dopant on A-site and Nb 5+ as a B-site donor. Both modifier impurities promoted a phase evolution from the coexistent of two phase structures (rhombohedral-tetragonal) into a more symmetric single pseudocubic structure. Nonetheless, (La,Nb) donor-donor doping induced the phase transition at 1 mol%, while (Li,Nb) acceptor-donor doping at 2 mol%. Interestingly, acceptor-donor (Li,Nb) co-substitution results in the broadening of ergodic relaxor and ferroelectric (ER-FE) mixed phase boundary which is favourable for multidevice applications. This comparative study show that the A-site vacancies play a substantial role to induce the phase transformation from nonergodic-ergodic relaxor (NR-ER) and the improvement in their high voltage induced strain.

Permanent photodoping of plasmonic gallium-ZnO nanocrystals

The concentration of delocalized electrons in plasmonic metal oxide nanocrystals can be increased permanently by photodoping because the electron compensation becoming the dominant compensation mechanism for the aliovalent donor dopant.

Enhanced thermoelectric properties of n-type Ti-doped PbTe

Thermoelectric (TE) generators, converting waste heat to electricity regain their attractiveness for reduction of fossil fuels’ reliance, and consequently minimizing adverse environmental effects. Such generators are based on an electrical series connection of TE couples, which consist n- and p- type semiconducting legs divided by metallic bridges. While for intermediate temperatures of up to 500°C, n-type PbTe was extensively studied and employed in commercial TE power generation applications, its maximal efficiency, as was reflected by the TE figure of merit, ZT, was in most of the cases maximized at a narrow temperature range for any given donor dopant concentration. The most commonly applied donor dopants are iodine and bismuth. Yet, some interesting characteristics were recently proposed upon using Ti as a donor dopant. Up to date an impressive maximal ZT of ∼1.2 was obtained at 500°C, upon doping of PbTe by 0.1 at.% Ti, while no lower concentrations were ever investigated. In the current research a lower, 0.05 at.% Ti doping level was applied, leading to the highest ever reported ZT values, for any given Ti doped PbTe, up to 350°C. Since the chemical compatibility of Ti with PbTe, as a metallic bridge in such couples, is well established, mainly due to its low diffusion rates, the potential of generating a stable Ti-doped functionally graded n-type PbTe material, with enhanced TE performance, is currently being proposed.

Synthesis, Crystallization, and Dielectric Behaviour of Lead Bismuth Titanate Borosilicate Glasses with Addition of 1% La2O3

Lead bismuth titanate borosilicate glasses were prepared in the glass system 65[(PbxBi1-x)·TiO3]-34[2SiO2·B2O3]-1La2O3 (0.0≤x≤1.0) doped with one mole percent of La2O3 via conventional melt quench method. The amorphous nature of glass samples in this glass system is confirmed by using X-ray diffraction (XRD) study. Differential thermal analysis (DTA) has been employed to determine the glass transition temperature, Tg, as well as crystallization temperature, Tc. DTA measurements were recorded in temperature range from 30 to 1200°C. The prepared glasses were crystallized by regulated controlled heat treatment process on the basis of their DTA results. These samples are carried out for XRD measurements in the 2θ range from 20 to 80° to study the crystallization behaviour and phase formation of the glass ceramic samples. The scanning electron microscopy (SEM) of these glass ceramic samples has been carried out to explore the morphology through nucleation and growth of the crystallites in the glassy matrix. The values of dielectric constant as well as dielectric loss were increased with increasing the temperature within the frequency range from 20 Hz to 100 Hz. The addition of 1 mol% of La2O3 to the lead bismuth titanate glasses enhances the crystallization and acts as donor dopant for this glass system.

The Influence of Donor-Doped Content on PTCR Effect of (Ba1-xSmx)TiO3 Based Ceramics Prepared by the Reduction Sintering-Reoxidation Method

We investigated the effect of the donor-doped content on the positive temperature coefficient of resistivity (PTCR) of (Ba1-xSmx)TiO3(BST) Based Ceramics that were sintered at 1300 °C for 30 min in a reducing atmosphere and re-oxidized at 850 °C for 1 h. The results indicated that the resistance jump first increased and then decreased with an increase of the donor-doped concentration. Moreover, the specimens achieved a low room temperature resistivity of 383.1 Ω·cm at a donor-doped content and exhibited a pronounced PTCR characteristics with a resistance jump of 3.1 orders of magnitude. Furthermore, the RT reisistivity of the samples reduced and increased with the increasing of the donor-dopant content in the range of 0.1−0.5 mol% Sm3+. In addition, the effect of the Sm3+-doped concentration on the grain size of the ceramics was investigated in our paper.

The Influence of Donor-Doped Content on PTC Effect of Ba-Excess BaTiO3 Based Ceramics Fired in Reducing Atmosphere

We investigated the influence of the Sm-doped contentration on the electrical properties and PTC effect of Ba-excess BaTiO3Based Ceramics, which were fired at 1300 °C for 30 min in a reducing atmosphere and then reoxidized at 850 °C for 1 h. The results showed that the donor dopant affected PTC characteristics and the electrical properties of the BSMT ceramics, whose room temperature resistivity first decreased and then increased with an increase in the Sm3+-doped content across the range from 0.1 to 0.5 mol%. The BSMT specimens exhibited a remarkable PTC effect, with a resistance jump greater by 2.7 orders of magnitude, along with a low room temperature resistivity of 128.6 Ω∙cm at the donor-doped content of 0.3 mol%. The influence of the donor dopant on the grain size of the as-fired samples has been also investigated.

A Novel Low-Temperature-Fired Multifunctional Varistor-Magnetic Ferrite Materials

A novel low temperature-fired (950°C) multifunctional varistor-magnetic ferrite materials can be obtained by adding V2O5 into CuCr0.2Fe1.8O4 ferrites. The relationship between the grain-boundary composition and varistor properties were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersion spectroscopy (EDS), and X-ray photoelectric spectroscopy (XPS). The addition of V2O5 can effectively reduce the sintering temperature of CuCr0.2Fe1.8O4 ferrites to temperatures of lower than 950°C. Moreover, the V5+ ions occupied the octahedral site of spinel structure and acted as donor dopant, which resulted in the semiconductive grain. The copper-rich observation at the grain boundary based on the TEM and EDS results implied that copper oxide would possibly develop at the grain boundary as the acceptor state, forming double Schottky barriers with the n-type semiconductor grains.