Electric field and temperature dependence of hole mobility in electroluminescent PDY 132 polymer thin films

The current density–voltage ($J\text{–}V$) behavior of polymer PDY 132 thin films has been investigated in hole-only device configuration, viz., ITO/poly(ethylene-dioxthiophene):polystyrenesulphonate (PEDOT:PSS)/PDY 132/Au, as a function of polymer (PDY) film thickness (150 nm and 200 nm) and temperature (290–90 K). Hole current density was found to follow two distinct modes of conduction, (i) low electric field region I: ohmic conduction where slope $～1$, and (ii) intermediate and high electric field region II: non ohmic conduction where slope $～2$. Region I has been attributed to the transport of intrinsic background charge carriers while region II has been found to be governed by space charge limited currents (SCLC) with hole mobility strongly dependent on electric field and temperature. The respective hole transport parameters determined from the SCLC regime, ${\mu }_{p0}$ is $3.7\times 10^{?3}{m}^2/Vs$, ${\mu }_p(0,T)$ is $3.7\times 10^{?8}{m}^2/Vs$, and zero field activation energy (${\Delta }_0$) of 0.48 eV is obtained.     

Quantum point contact conductance in normal metal/insulator/ metal/dx2−y2+idxy mixed wave superconductor junctions

The tunneling conductance in a normal metal/insulator/metal/$d_{x^2?y^2}+i{d}_{xy}$ mixed wave superconductor (N/I/N/$d_{x^2?y^2}+i{d}_{xy}$) junction is calculated, where the N/I/N region is a quantum wire. It is found in the single-mode case that the magnitude of the tunneling conductance near zero voltage is enhanced due to the Andreev bound state by quasiparticles with perpendicular and horizontal injection, and the zero-bias conductance varies with $L$ ($L$ is the distance from insulating layer to the interface of N/$d_{x^2?y^2}+i{d}_{xy}$ mixed wave superconductor). Splitting of the zero-bias conductance peak appears in the quantum point contact tunneling spectra for an N/I/N/$d_{x^2?y^2}+i{d}_{xy}$ junction, and several subgap peaks can split at the same time. On increasing both $L$ and the magnitude ratio of the two components for the $d_{x^2?y^2}+i{d}_{xy}$ mixed wave, the subgap resonances exhibit an alternately high and low behavior inside the energy gap. These results are different from those in d-wave and p-wave superconductor junctions.     

Lattice dynamics and phase transition of NiTi alloy

We have performed detailed first-principles calculations to investigate the structural and lattice dynamical properties of NiTi alloy. The calculated static structures consist well with the experimental data and other theoretical results. With quasi harmonic approximation, the phase boundary between B19′ and BCO phases can be described as a five order polynomial $T=100?89.28P+296.75P^2?717.94P^3+734.62P^4?274.25P^5$. The change of vibrational entropy is $0.07k_B$/atom at the transition temperature 100 K under zero pressure.     

Photoluminescence of ZnO ceramics sintered with a flux

ZnO ceramics both with and without boric acid as a flux were sintered at $T_S=800\text{–}1200{}^{°}C$ and their luminescent characteristics were compared. In obtained samples UV as well as visible emission bands were observed. The addition of the flux was shown to cause the increase of grain size and the improvement of crystalline quality of the ceramics, which was ascribed to the creation of a liquid phase during the sintering process. It was found that the adding of 1 wt% of boric acid to ZnO powder allowed ceramics preparation without any pressing of the starting materials, in this case $T_S=950{}^{°}C$ being enough to obtain firm and dense ceramics. This ceramics had higher intensity of UV emission and lower intensity of visible emission than ceramics sintered without the flux.     

Spin-glass behavior in the antiperovskite manganese nitride Mn3CuN codoped with Ge and Si

Antiperovskite manganese nitrides ${\mathrm{Mn}}_3\left({\mathrm{Cu}}_{0.6}{\mathrm{Si}}_x{\mathrm{Ge}}_{0.4?x}\right)N$ ($x=0.05$, 0.1, 0.15) were prepared and their negative thermal expansion, magnetic and specific heat properties were investigated. A frozen state with a freezing temperature was found at ～207 K in ${\mathrm{Mn}}_3\left({\mathrm{Cu}}_{0.6}{\mathrm{Si}}_{0.15}{\mathrm{Ge}}_{0.25}\right)N$. This indicates that ${\mathrm{Mn}}_3\left({\mathrm{Cu}}_{0.6}{\mathrm{Si}}_{0.15}{\mathrm{Ge}}_{0.25}\right)N$ exhibits a spin glass state at low temperatures. We discussed the cause of spin glass behavior and correlated this spin glass behavior with broadening of the negative thermal expansion operation-temperature window of the manganese nitrides ${\mathrm{Mn}}_3\left({\mathrm{Cu}}_{0.6}{\mathrm{Si}}_{0.15}{\mathrm{Ge}}_{0.25}\right)N$.     

Persistent luminescence and synchrotron radiation study of the Ca2MgSi2O7:Eu2+,R3+ materials

The tetragonal ${\mathrm{Ca}}_2{\mathrm{MgSi}}_2{\mathrm{O}}_7$:${\mathrm{Eu}}^{2+},{\mathrm{R}}^{3+}$ persistent luminescence materials were prepared by a solid state reaction. The UV excited and persistent luminescence was observed in the green region centred at 535 nm. Both luminescence phenomena are due to the same ${\mathrm{Eu}}^{2+}$ ion occupying the single ${\mathrm{Ca}}^{2+}$ site in the host lattice. The ${\mathrm{R}}^{3+}$ codoping usually reduced the persistent luminescence of ${\mathrm{Ca}}_2{\mathrm{MgSi}}_2{\mathrm{O}}_7$:${\mathrm{Eu}}^{2+}$, which differs from the ${\mathrm{M}}_2{\mathrm{MgSi}}_2{\mathrm{O}}_7$:${\mathrm{Eu}}^{2+}$ $(\mathrm{M}=\mathrm{Sr},\mathrm{Ba})$ and ${\mathrm{MAl}}_2{\mathrm{O}}_4$:${\mathrm{Eu}}^{2+}$ $(\mathrm{M}=\mathrm{Ca},\mathrm{Sr})$ materials. Only the ${\mathrm{Tb}}^{3+}$ ion enhanced slightly the persistent luminescence. With the aid of synchrotron radiation, the band gap energy of ${\mathrm{Ca}}_2{\mathrm{MgSi}}_2{\mathrm{O}}_7$:${\mathrm{Eu}}^{2+}$ was found to be about 7 eV that is very similar to those of the ${\mathrm{M}}_2{\mathrm{MgSi}}_2{\mathrm{O}}_7$:${\mathrm{Eu}}^{2+}$ $(\mathrm{M}=\mathrm{Sr},\mathrm{Ba})$ materials. Thermoluminescence results suggested that the ${\mathrm{R}}^{3+}$ ions might act as electron traps, but only the TL peaks created by ${\mathrm{Tm}}^{3+}$ and ${\mathrm{Sm}}^{3+}$ can be found in the temperature range accessible. Lattice defects (e.g. oxygen vacancies) are also important, since the same main thermoluminescence peak was observed at about $100{}^{\circ }\mathrm{C}$ with and without ${\mathrm{R}}^{3+}$ codoping.     

Effect upon universal order of Hubble expansion

The level of order $R$ in a spherical system of radius $r_0$ with a probability amplitude function $\psi \left(x\right),x=r,\theta ,?$ obeys $R=(1/2)r_0^{2}I$, where $I=4\int dx{\left|?\psi \right|}^2$ is its Fisher information level. We show that a flat space universe obeying the Robertson–Walker metric has an invariant value of the order as it undergoes either uniform Hubble expansion or contraction. This means that Hubble expansion per se does not cause a loss of universal order as time progresses. Instead, coarse graining processes characterizing decoherence and friction might cause a loss of order. Alternatively, looking backward in time, i.e. under Hubble contraction, as the big bang is approached and the Hubble radius $r_0$ approaches small values, the structure in the amplitude function $\psi \left(x\right)$ becomes ever more densely packed, increasing all local slopes $?\psi$ and causing the Fisher information $I$ to approach unboundedly large values. As a speculation, this ever-well locates the initial position of the universe in a larger, multiverse.     

222Rn concentrations of water in the Balaton Highland and in the southern part of Hungary,and the assessment of the resulting dose

In this study the ²²²Rn concentration of mains water in 120 settlements in Hungary (Southern Hungary, the Balaton Highland region) was measured. The average ²²²Rn concentration was 5.56 $(0–24.3)\mathrm{Bq}{\mathrm{l}}^{-1}$. On the basis of the ²²²Rn concentration of mains water inspected in the Southern Great Plain region, it can be stated that the ²²²Rn concentration of mains water here is, as an average, half of the ²²²Rn concentration of fountains in the same region. This decrease in radon probably happens during the water management and storage of mains drinking water. The ²²²Rn concentration of spring-water examined in the region of the Balaton Highland exceeds the average ²²²Rn concentration of drinking water (average $27.1\mathrm{Bq}{\mathrm{l}}^{-1}$).The radiation dose originating from the consumption of mains drinking water in case of adults does not reach the value of $0.1\mathrm{mSv}{\mathrm{year}}^{-1}$, even as a conservative assessment ($1\mathrm{l}{\mathrm{day}}^{-1}$ water consumption and ${10}^{-8}\mathrm{Sv}{\mathrm{Bq}}^{-1}$ dose conversion factor).     

Luminescent, optical and color properties of natural rose quartz

Rose quartz is an interesting mineral with numerous impurities that have been studied by scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD), cathodoluminescence (CL), ion beam luminescence (IBL), radioluminescence (RL), thermoluminescence (TL) and optical absorption (OA). After HF etching, rose quartz from Oliva de Plasencia (Caceres, Spain) shows under SEM the presence of other silicate phases such as dumortierite $[{\mathrm{Al}}_{6.5-7}({\mathrm{BO}}_3)({\mathrm{SiO}}_4{)}_3(\mathrm{O},\mathrm{OH}{)}_3]$. The OA spectrum of rose quartz suggests that these inclusions are the cause of coloration of rose quartz. The luminescence (CL, IBL, RL, TL) spectra behavior, at both room temperature and lower, confirms that the $\sim 340\mathrm{nm}$ emission could be associated with Si–O strain structures, including non-bridging oxygen or silicon vacancy–hole centers; the observed $\sim 400\mathrm{nm}$ emission could be associated with recombination of a hole trapped adjacent to a substitutional, charge-compensated aluminum alkali ion center; the $\sim 500\mathrm{nm}$ emission could be associated with substitutional ${\mathrm{Al}}^{3+}$ and the $\sim 700\mathrm{nm}$ peak could be associated with ${\mathrm{Fe}}^{3+}$ point defects in ${\mathrm{Si}}^{4+}$ sites. These results suggest that, while defect properties of rose quartz are not greatly dissimilar to those of purer forms of quartz and silica, further research seems necessary to determine criteria for the evolution of the newly-formed self-organized microstructures in the rose quartz lattice under irradiation.