We use ultrafast coherent two-dimensional electronic spectroscopy (2DES) to study the ultrafast spectral diffusion dynamics of colloidal CdSe quantum dots (QDs) and CdSe nanoplatelets (NPLs). The Center Line Slope (CLS) and Nodal Line Slope (NLS) techniques were employed to analyse the 2DES spectra. We show that no spectral diffusion dynamics occurs for the CdSe QDs. On the other hand, spectral diffusion was observed in the CdSe 5 mono-layers NPLs heavy-hole transition. The normalized Frequency Fluctuation Correlation Function (FFCF) of the CdSe NPLs heavy-hole transition was measured to have a major fast decay component at 140 fs.

We present results of time-domain Brillouin scattering (TDBS) to determine the local temperature of liquids. TDBS is based on an ultrafast pump-probe technique to determine the light scattering frequency shift caused by the propagation of coherent acoustic waves in a sample. Since the temperature influences the Brillouin scattering frequency shift, the TDBS signal probes the local temperature of the liquid. Results for the extracted Brillouin scattering frequencies recorded at different liquid temperatures and at different laser powers are shown to demonstrate the usefulness of TDBS as a temperature probe.

We report on the time-resolved measurements of photocarrier dynamics in InGaAs/InAlAs superlattices with epitaxial stresses in a wide range of optical pump fluences. We demonstrated that the contribution of free carrier absorption and two-photon absorption to the carrier dynamics decreases with an increase of epitaxial stresses. The lowest relaxation times of 1.7 and 8.3 ps, respectively attributed to carrier trapping and carrier recombination, were obtained for the structure with maximum epitaxial stresses.

In this study, we report developments towards the application of large zeolite particles, with diameter ca. 40 μm, as tracers in Positron Emission Particle Tracking (PEPT) imaging using 68Ga. The influence of intrapore Na+ and TEA+ (tetraethylammonium) cation concentrations and framework Si/Al ratio on the morphology of mordenite particles has been investigated, advancing understanding of the relationship between these factors. Moreover, the influence of ethanol concentration in the gel during aging on intrapore cation concentration, Si/Al ratio and particle morphology has also been investigated. Additionally, facile ion-exchange between aqueous Ga3+ and intrapore H+ in mordenite has been demonstrated. The influence of pH and gallium speciation on ion-exchange has been investigated to determine favourable conditions for 68Ga3+ uptake by the zeolite.

Sn2Nb2O7 and SnNb2O6 are promising candidates for wide-gap p-type conducting oxides with high mobility, because their valence-band maximum are composed of Sn 5s orbital with large spatial spreading and isotropic nature. Though hole carriers were generated by Sn4+ substitutional defects on Nb5+ site (Sn’Nb) in the substructure of Nb2O6 octahedra in both tin niobates, the generation efficiency of hole carriers in SnNb2O6 was larger than that of Sn2Nb2O7. From the variation in bond length of Nb-O in the Nb2O6 octahedra calculated by Rietveld analysis, the difference in carrier generation efficiency of two tin niobates was examined. The bond length of Nb-O in p-type Sn2Nb2O7 with large amounts of Sn’Nb was smaller than that of n-type Sn2Nb2O7 with small amounts of Sn’Nb. The holes generated by Sn’Nb were considered to be captured by the negative charge of oxygen anions consisting of the Nb2O6 octahedra, resulting in low carrier generation efficiency. In SnNb2O6 showing higher efficiency, Nb-O was 8.6 % larger than that of p-type Sn2Nb2O7. It is considered that the large Nb-O bond length provide the preferred environment for the generation of positive holes, resulting in the higher carrier generation efficiency.

A novel series of temperature stable Li3Mg2NbO6–xTiO2 ceramics were prepared by the conventional solid-state route. The effects of TiO2 addition on the sintering behavior, phase composition, microstructure and microwave dielectric properties were investigated systematically. The dense microstructure could be obtained in low TiO2 content (x=0.1) samples sintered at 1100 °C. The dielectric constant εr was attributed to the bulk density and TiO2 content. The variation in Q×f values is related to the bulk density, and improved values could be obtained for Li3Mg2NbO6–0.1TiO2 ceramics. The quality factor (Q×f) had a maximum for x=0.1 and the temperature coefficient of resonant frequency (τf) value shifted towards positive direction with the increase of TiO2 addition. Notably, Li3Mg2NbO6–0.1TiO2 ceramics sintered at 1100 °C possessed excellent microwave dielectric properties: εr=15, Q×f =74,000 GHz(9.93GHz), τf= −3.4 ppm/°C, which made the ceramics as promising low loss and temperature stable candidates for millimeter-wave applications.

Traditional synthesis of high-performance bulk ferrites include complex sintering procedures where temperature and soak times to obtain high densities and excellent magnetic properties. Most ferrites must be sintered at hundreds degree centigrade approaching or surpassing 1000oC, and for YIG (yttrium iron garnet), the sintering temperature should be approximately 1450°C. The high sintering temperatures limit the applications of ferrites, for example, the low temperature co-sintering of ceramics with silver electrodes and/or ground planes. For decades, researchers have explored the use of ion-doping, sintering aids, and microstructural refinement. Here, we study the optimization of the sintering profile including multiples temperature and soak times for doped Bi-YIG simples. The results show an improvement in soft magnetic and gyromagnetic properties attributed to the homogenization of grain size and morphology.

Disordered iron oxide thin-films synthesized from grain-oriented iron foils were grown on both glass and Si (100) n-type substrates by vacuum evaporation followed by thermal oxidation at low temperatures. Defects such as vacancies formation has been studied using Atomic Force Microscopy (AFM) and Raman Spectroscopy. The kinetic of oxidation as a function of surface parameters was investigated by AFM studies. The vibrational modes (bands) connected with the vacancies formation and magnetic ordering into the iron oxide structure were validated by Raman spectroscopy. Space-charge effects can be influenced by discontinuous growth of iron oxide and correlated with their structure parameters. Finally, the disordered iron oxide will be useful for the next generation of adaptive oxide devices.

κ-Al2O3-type GaFeO3 is a promising multiferroic material due to the coexistence of a large spontaneous magnetization and polarization near room temperature. In the current study, we present the magnetic properties of single crystalline GaFeO3 and compare it with that of ε-Fe2O3. Magnetic measurements revealed that spontaneous magnetization appears below 540 K in two steps, similar to that reported for ε−Fe2O3. Partial magnetic ordering takes place at 540 K (TN1), with Fe3+ ions in two distorted octahedral sites ordering antiparallel to one another. Upon further cooling at 200 K (TN2), the remaining Fe3+ ions in regular octahedra and tetrahedra order antiparallel to one another. Substitution of Ga for Fe in ε-Fe2O3 leads to a decrease in TN1 and TN2 from 850 to 540 K and from 480 to 200 K, respectively, caused by a dilution of magnetic Fe by nonmagnetic Ga and preferential site occupation of Ga.