Hyperfine interactions in europium orthophosphate EuPO 4 were investigated using 151 Eu Mössbauer spectroscopy from 6 to 300 K. The value of the quadrupole splitting and the asymmetry parameter were refined and further substantiated by nuclear forward scattering data obtained at room temperature. The temperature dependence of the relative absorption was modeled with an Eu specific Debye temperature of 221(1) K. Eu partial lattice dynamics were probed by means of nuclear inelastic scattering and the mean force constant, the Lamb-Mössbauer factor, the internal energy, the vibrational entropy, the average phonon group velocity were calculated using the extracted density of phonon states. In general, Eu specific vibrations are characterized by rather small phonon energies and contribute strongly to the total entropy of the system. Although there is no classical Debye like behavior at low vibrational energies, the average phonon group velocity can be reasonably approximated using a linear fit.

The lattice dynamics of polycrystalline Mg(2)Ge and Mg(2)Si are compared using both microscopic and macroscopic measurements as well as theoretical calculations. The volume thermal expansion coefficient between 200 and 300 K was found to be 4.37(5) · 10(-5) K(-1) in Mg(2)Ge, compared to 3.69(5) · 10(-5) K(-1) in Mg(2)Si. Inelastic neutron scattering measurements yield densities of phonon states which are in line with theoretical calculations. The microscopic data were corroborated with macroscopic calorimetry measurements and provide quantified values for anharmonicity. The estimated macroscopic Grüneisen parameter is, γ(Mg(2)Si) = 1.17(5) and γ(Mg(2)Ge) = 1.46(5) at 295 K, in excellent agreement with Raman scattering data. Although the element specific mean force constants are practically the same, in Mg(2)Ge and Mg(2)Si, a mass homology relation alone cannot reproduce the difference in the partial densities of vibrational states in these compounds and differences in elemental bonding should be taken into account.

We investigated the lattice dynamics of Sb2Te3 under high pressure using Sb-121 and Te-125 nuclear inelastic scattering of synchrotron radiation. We measured the room temperature Sb-121 and Te-125 inelastic spectra at 15(1) GPa and 77(3) GPa and extracted the Te and Sb element specific density of phonon states of delta-Sb2Te3 at 77(3) GPa. X-ray diffraction confirms the sample to be in the cubic delta-Sb2Te3 phase with space group Im (3) over barm and lattice constant a = 3.268(4) angstrom. The total density of phonon states of delta-Sb2Te3 strongly resembles the one of amorphous GeSb2Te4, suggesting the presence of covalent bonding in contrast to the resonance bonding in alpha-Sb2Te3. From the density of phonon states of delta-Sb2Te3 a mean speed of sound of 2.61(6) km s(-1) and Debye temperatures of 278(10) K for Te and 296(10) K for Sb were determined.

We measured nuclear forward scattering of synchrotron radiation by the 68.7 keV nuclear resonance of Ge-73 with a half-life T-1/2 = 1.74 ns. The Debye temperatures of CaGeO3 in the wollastonite, garnet and perovskite phases were determined to be 386(20) K, 437(20) K and 507(20) K, respectively, and 309(20) K and 459(11) K for GeO2 in the quartz and rutile phases, respectively. The isomer shift is clearly dependent on the Ge valence but not directly on the coordination geometry. The so far unknown magnetic moment mu e of the 68.7 keV excited state of Ge-73 is determined to be -0.84(22) mu N. Time domain Ge-73 Mossbauer spectroscopy with the 68.7 keV resonance is feasible for isomer shift and Debye temperature measurements but so far neither electric quadrupole nor magnetic hyperfine interactions could be observed. Copyright (C) EPLA, 2013

This chapter discusses in detail a RS HfO2-based memory cell with a metal-insulator-metal (MIM) vertical structure in which the HfO2 was deposited by Atomic Layer Deposition (ALD). The author carries out a statistic study on the effect of the HfO2 deposition process conditions on the resistive switching behavior. The chapter investigates the transient currents during 5-ns resistive switching operations. It proposes a short voltage pulse induced electroforming. The chapter models the current transport in metal-oxide-metal structures to gain an in-depth insight into the electroforming process. It reports the fabrication and electrical characterization of two-terminal multistate memory devices based on VO2/TiO2 thin film microcantilevers. The chapter reports on the feasibility of the Ge2Sb1Te4, Ge3Sb4Te8 and Ge2Sb2Te4 alloys and the effect of vacancies on their physical properties. It aims to determine. Controlled Vocabulary Terms atomic layer deposition; cantilevers; MIM structures