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This work presents the investigation of resistive switching memory in a perovskite heterostructure composed of an active Al-Nb codoped Pb(Zr0.52Ti0.48)O3ferroelectric thin film and a semiconducting Pr0.7Ca0.3MnO3manganite-based oxide film, both sandwiched between Pt electrodes in a parallel capacitor-like structure. Bipolar resistive switching nature was confirmed from the measured characteristics of the DC I-V hysteresis loop and resistance switching in the pulse mode. The active ferroelectric layer has been demonstrated to play a crucial role in controlling the switching memory performance (resistance state stability and high switching endurance). Ferroelectric polarization and corresponding piezoelectric effect-induced lattice strains are found to be responsible for the resistive switching characteristics in this ferroelectric/manganite heterojunction.

The novel electric-pulse-induced resistance (EPIR) switching effect has been obtained in metal electrode- Pr0.7Ca0.3MnO3 (PCMO)-metal electrode capacitor-like film structures. The EPIR effect encompasses the reversible change of resistance of PCMO under the application of short, low voltage pulses. This reversible resistance switching at room temperature is very attractive for today's computing technology with its wide applications as a resistance random access memory (RRAM) due to its nonvolatility, fast write/read/erase speed, low power-consumption and high radiation-hardness. In this work, a nano-meter thick ferroelectric Pb0.7Zr0.3TiO3(PZT) layer was inserted between the top electrode and PCMO film as a buffer layer in the EPIR device. Such a resistive memory device is comprised of a PCMO epitaxial layer on a c-oriented YBCO bottom electrode layer and a PZT ferroelectric buffer layer grown on top of the PCMO layer with an Ag top electrode. Compared with the Ag/PCMO/YBCO devices, the insertion of the PZT buffer into the Ag/PCMO interface is found to make the EPIR ratio increase greatly and the threshold pulse voltage necessary to switching the resistive device decrease significantly. Since Pr1-xCaxMnO3 is a unique compound oxide, showing semiconductive behavior over the whole composition (x) range, this is attributed to the resistive change of the depletion region at the Ag/PCMO interface including the PZY buffer, in which ferroelectric polarizations play a crucial role in the enhanced EPIR switching effect.

The first results of an EPR dose reconstruction with tooth enamel from eyewitnesses of the nuclear test at Totskoye, Southern Urals, Russia, are presented. This test was performed on 14 September 1954, when a nuclear device was detonated at a height of 350 m. The declared power of the explosion was 40 kt. Ten radiation doses have been reconstructed in the framework of the present study. Six of them were found to be higher than 0.4 Gy. The investigations performed have demonstrated a potential ability of EPR retrospective dosimetry to provide additional independent dose estimation for a population exposed as a result of the Totskoye nuclear test. The doses reconstructed for donors who were closer to the site during the nuclear test turned out to be considerably higher (up to factor of 10) than those for the donors who were further from the explosion site. Therefore, a crucially important factor to be borne in mind in collecting samples is the distance between the donor and the explosion site at the time of the explosion.

In situ annealed high temperature superconducting YBa2Cu3O7-?thin films have been deposited on an MgO (100) substrate from a single stoichiometric target using DC magnetron sputtering. The films were characterized by X-Ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The effect of varying substrate temperature, Ts, and O2/Ar ratio on lattice parameters and on the degree of orientation of the films were examined. Both c- and a-lattice parameters decreased with increasing Ts. The reduction of cand a-lattice parameters as well as the oxygen deficiency in the films, ?, obey general (Ts- T0)-4behavior. We develope a new method to measure a more accurate way to find the degree of preferrential orientation along cand a-axis of the deposited films, (?V006/?V200), at different Tsby using X-ray diffraction theory and JCPDS files to obtain ?F(006)/F(200)?2. At Ts=735°C, the volume fraction along the c-axis was found to be ?Vc?5.5 ×?Vacorresponding to 85 grains having preferred orientation along c-axis. In addition, we have also measured FWHM of the (006) and (200) peaks by varying Ts. The thickness of the grains were estimated at different substrate temperature using the Scherrer formula.

Cationic radicals generated by anodic oxidation of organophosphorus (III) compounds are superelectrophilic radicals. This determines the pattern of their reactivity towards various substrates. The oxidation of (RO)2PO- and (RO)2PS- gives corresponding radicals. Interaction of the mentioned radical species with ArH and olefines includes a common stage of radical adduct formation. It has been stated that the oxidation of the adduct into corresponding carbonium ion plays an important role in the following adduct conversions. This is particularly confirmed by the difference in the composition of products obtained in conditions of homogeneous (via photolysis or with stable radical cations) and heterogeneous (on the anode surface) generation of phosphorylating species.

Ferroelectric Pb(Zr0.52Ti0.48)O3(PZT) thin films were integrated to high-Tcsuperconducting YBa2Cu3O7-?(YBCO) films in PZT/YBCO/MgO(100) and YBCO/PZT/MgO(100) stacking structures by the pulsed laser ablation technique. The YBCO films in both structures were superconducting and c-axis oriented. The PZT films in both structures were of the perovskite structure having the (100) orientation. The detailed profile of PZT/YBCO interface was determined for the ferroelectric constituents. The ferroelectric properties of the PZT films were characterized in the temperature range of 40 K to 300 K. The remanent polarization was above 15 µC/cm2and the coercive field was 46 kV/cm at room temperature. The cycling fatigue and the loss tangent were improved at low temperature.