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We study single crystal zirconia using molecular dynamics method. We calculate the diffusion coefficient of oxygen ions in the temperature range from the occurrence of diffusion at our calculation parameters to the loss of stability of the crystal. In the potential of interatomic interactions, in addition to conventional terms, we introduce into our model the interaction due to the polarization of atoms. These interactions turned out to be crucial for the correspondence between the calculations and available experimental data.

We demonstrate that the state-of-the-art postirradiation technology for negatively charged oxygen (O−) ions is effective for tailoring carrier concentration (n e ), electrical resistivity (ρ), and optical band gap (E g) in a wide range for polycrystalline 50-nm-thick Sn-doped In2O3 (ITO) films on glass substrates by reactive plasma deposition with direct-current arc discharge. As-deposited ITO films showed n e of 9.2 × 1020 cm−3, ρ of 1.5 × 10−4 Ω cm, and E g of 3.50 eV. The postirradiation of O− ions for 180 min at 250 °C decreased n e to 2.4 × 1018 cm−3. This resulted in a significant increase in ρ to 3.5 × 10−1 Ω cm while retaining the bixbyite crystal structure and the spatial distribution of Sn dopant atoms. The postirradiation of O− ions led to the continuous decrease in the optical E g ranging from 3.50 to 3.02 eV, which is smaller than that of undoped In2O3. For degenerate ITO films, conventional theories about the broadening and narrowing of the optical E g explain the experimental results well. On the other hand, for nondegenerate ITO films, the optical E g shrinkage would be mainly caused by an upward energy shift attributable to the generation of the anti-bonding π* states between O 2p and In 4d orbitals within the topmost valence band owing to the lattice disorder associated with incorporated interstitial oxygen atoms that fill structural vacancy sites. On the basis of the Ioffe–Regel criterion utilizing the electron mean free path, Fermi momentum, and their product, we determined the critical n e at which degenerate ITO films transform to nondegenerate ones.

This study presents the effect of low energy (120 KeV) O-ions implantation on the photosensitivity of PbS thin films by vacuum thermal evaporator (VTE). The crystallite size (D) of PbS films decreased from 32.8 nm to 17.4 nm and the bandgap (E g) increased from 1.61 eV to 1.76 eV as the fluence increased from 0.5 × 1016 ions cm−2 to 1.5 × 1016 ions cm−2. The PL spectra of O-ions implanted PbS thin films showed a dominant peak at 381 nm regardless the fluence of implantation. The photocurrent sharply increased by the implantation of O-ions (0.5 × 1016 ions cm−2) due to the creation of ‘shallow traps’ in the forbidden gap of PbS thin films under illumination of visible light (100 mW cm−2). The highest photosensitivity of O-ions implanted PbS thin films was observed due to the creation of proper traps for the photoconduction for the particular dose of 0.5 × 1016 ions cm−2.

In this paper, we report our investigation of room-temperature-fabricated tungsten/indium tin oxide/gold (W/ITO/Au) resistive random access memory (RRAM), which exhibits asymmetric bipolar resistive switching (BRS) behavior. The device displays good write/erase endurance and data retention properties. The device shows complementary resistive switching (CRS) characteristics after controlling the compliance current. A WO x layer electrically formed at the W/ITO in the forming process. Mobile oxygen ions within ITO migrate toward the electrode/ITO interface and produce a semiconductor-like layer that acts as a free-carrier barrier. The CRS characteristic here can be elucidated in light of the evolution of an asymmetric free-carrier blocking layer at the electrode/ITO interface.

The measurement of layer thickness by compositional secondary ion mass spectrometry (SIMS) depth profiling is investigated for Si/Ge multilayer films using an oxygen ion beam. The original SIMS depth profiles were converted into compositional depth profiles by the relative sensitivity factors of Si and Ge derived from a Si52.4Ge47.6 alloy reference film. The locations of the interfaces in the Si/Ge multilayer films could be well determined by 50 at% definition where the relative composition of the constituent layer elements drops or rises to 50 at%. The layer thicknesses of Si and Ge of a test Si/Ge multilayer film were determined by the sputtering rates of Si and Ge determined from a reference Si/Ge multilayer film. Although the difference between the measured and the actual thicknesses is increased as the ion energy is increased, the layer thicknesses determined at low ion energies were very close to the actual values.

The transmissions of oxygen ions through Al2O3 nanocapillaries each 50 nm in diameter and 10 μm in length at a series of different tilt angles are measured, where the ions with energies ranging from 10 to 60 keV and charge states from 1 up to 6 are involved. The angular distribution and the transmission yields of transported ions are investigated. Our results indicate both the existence of a guiding effect when ions pass through the capillary and a significant dependence of the ion transmission on the energy and the charge state of the ions. The guiding effects are observed to be enhanced at lower projectile energies and higher charge states. Meanwhile, the results also exhibit that the transmission yields increase as the tilt angle decreases at a given energy and charge state.

Raman spectroscopy is utilized to study the evaluation of vacancies in PbTiO3 thin films subjected to hydrogen atmosphere heat treatment. The B1 mode consisted of only oxygen ion vibration was shifted to lower frequency with increasing heat treatment temperature. It was considered that the oxygen ions were lacking from PbTiO3, and that oxygen vacancies were generated. It was found that the frequency of the B1 mode is proportional to oxygen ion content. Pb ions were also lacking in the PbTiO3 thin films with oxygen ions and the number of oxygen vacancies was larger than that of Pb ions. We suggest that the Raman spectroscopy is a suitable tool for the evaluation of oxygen vacancies in PbTiO3 thin films.

A planar optical waveguide was formed in RbTiOPO4 crystal by 6.0-MeV oxygen ion implantation with the dose of 2×1015 ions/cm2 at room temperature. Annealing at 200°C for 30 min in air is performed to improve the thermal stability of the waveguide. The dark modes of the waveguide are measured at wavelengths 633 and 1539 nm, respectively. The refractive index profiles in the guiding layer are reconstructed by using the reflectivity calculation method. TRIM'98 code was carried out to simulate the damage profiles caused by the implantation process to obtain a better understanding of the waveguide formation.

The electric dipole intercombination decay rate of the 2s2p 3Po1 level in the Be-like ions N3+ and O4+ has been measured with ions circulating in a heavy-ion storage ring. The observation employed three devices in parallel, two different VUV photon detectors and a residual gas recoil ion detector. The measured transition probabilities of (578 ± 3.3) s−1 for N3+ (level lifetime τ = 1.73 ± 0.01 ms) and of (2315 ± 50) s−1 for O4+ (τ = 0.432 ± 0.009 ms), corroborate the results of recent calculations and improve the precision with which the isoelectronic trend can be established.

Work with ceramic samples of (CaxLa1−x)(LauBa1−u)2Cu3Oy (these compounds have previously been denoted as CLBLCO, CLBCO or CaLaBaCuO) has shown that ordinary cooling rates used after annealing at high oxygen pressures may result in samples having higher (overestimated) Tc values when compared to the fast cooled ones having the same y. Thus, exposure of a sample of x = 0.1 and u = 0.175 to temperatures lower than 200 °C, which occur during cooling, leads (without oxygen absorption) to an overestimation of the Tc value. Increase of the cooling rate by dropping the pellet into the cold part of the autoclave suppresses this effect. Another effect is oxygen absorption during cooling when it is performed after high temperatures of annealing. The products of this absorption have an inhomogeneous distribution of oxygen ions in the ceramic grain. Their Tc values are also overestimated.

The defects associated with lead vacancies (VPb) in lead tungstate crystals (PbWO4) are investigated by the relativistic self-consistent discrete variational embedded cluster method. We focus on the density of states and the effect of VPb on surroundings. The results show that the existence of VPb can diminish the bandwidth of WO42- group, however, it can neither produce O- and Pb3+ ions nor result in absorptions at 350 and 420 nm. The charge balance of VPb may be evenly compensated by the surrounding oxygen ions.

We clarified the mechanism of oxygen (O−)-ion migration at a high-k/SiO2 interface, which is a possible origin of the flat-band voltage shift in metal/high-k gate stacks. The oxygen density difference accommodation model was reproduced by a molecular dynamics simulation of an Al2O3/SiO2 structure, in which O− ions migrate from the higher oxygen density side to the lower one. We determined that the driving force of the O−-ion migration is the short-range repulsion between ionic cores. The repulsive force is greater in materials with a higher oxygen density, pushing O− ions to the lower oxygen density side.

We report the first measurement of the kinetic energy release distributions of multiply charged oxygen ions produced in collisions of O2 molecules with 5.9 MeV/amu Xe18+ and Xe43+ ions. The slow Oq+ ions generated in the collision are detected in coincidence by a time- and position sensitive multi- particle detector. An analysis of correlated momenta of molecular fragments provides the kinetic energy release distribution for various reaction pairs O2 → Oq1+Oq2+ with a total charge up to q = q1 + q2 = 11. The position of the maximum and the width of the distributions are well described by the recently suggested Average Bunch Statistical (ABS) model.

Oxygen ions are implanted into BiFeO3 films on LaNiO3/SrTiO3(1 0 0) substrates. The evolution of films is characterized by x-ray diffraction, scanning electron microscopy and cross-sectional transmission electron microscopy. The leakage current density of the implanted films is lowered by two orders of magnitude in comparison with unimplanted BFO films. The mechanisms for reduced leakage current in BiFeO3 thin films are discussed.

We report on the optical planar waveguide formation in KTiOPO4 crystals by single or double oxygen ion implantation at energies of 2.4–3.0 MeV and doses of 1015 ions/cm2. The dark-line spectroscopy properties are investigated by a prism-coupling method. With an effective refractive index method, the refractive index profiles of the waveguides are reconstructed. The program code TRIM'98 (transport of ions in matter) is used to simulate the implantation process of oxygen ions into the KTiOPO4 crystal. It is found that an inherent relationship exists between the nuclear damage and the refractive index changes induced by the ion-beam implantation.

Novel features have been observed in the projectile x-rays and radiative electron capture (REC) photons emitted from bare and H-like S ions of energy varying between 90 and 143 MeV and channelled along the direction in a Si single crystal. These features include enhancement of the photon yields along the channelled direction over that in a random case as well as their peaking close to . REC measurements have also been carried out for fully stripped and H-like oxygen ions at 84 MeV. All these results have been understood in terms of the electron capture and loss cross sections as well as the charge `freezing' of channelled ions.

New measurement of the ratio of the double ionization cross section to that of the single ionization of helium induced by 2.0-7.5 MeV partially stripped Oq+ ion (q = 1,2,3,4) is presented. Combining the measured data with the Olson-Schlachter scaling, the double ionization cross section of helium by partially stripped oxygen ion is obtained. It is found that the v/qeff dependence of the obtained double ionization cross section agrees well with the (v/qeff)-4 law.

The charge states of sputtered cesium and oxygen ions/atoms from metal surfaces have been discussed with the time-dependent Newns-Anderson model. The final charge state distribution has been calculated as a function of work function of the surfaces. The calculated results fit the experimental data well. Besides, the dependence of the final charge states of the sputtered oxygen particles on the surface temperature is also predicted.

Absolute cross sections for mutual neutralization of He+/O- and Na+/O- ions have been measured by a merged beam technique for interaction energies between 1.2 and 500 eV, and 0.6 and 330 eV respectively. The results for Na+/O- are in excellent agreement with inclined beam measurements by Peart and Foster (1987) in the overlapping range of energies. At interaction speeds greater than about 2*105 m s-1, results for He+/O-, Na+/O-, O+/O- and N+/O- appear to converge.

It was earlier found that the size of the binary encounter peak does not show a q2 scaling (q is the ionic charge) for partially stripped ions, but instead increases with the number of electrons carried by the projectile. Measurements of this enhancement of the binary encounter peak for collisions of fast Cq+ and Oq+ on H2 have for the first time been extended to the lowest ionic charge state. The authors get the surprising result that the enhancement for q=1 is smaller than for q=2.

Transition data has been computed in the MCHF + Breit-Pauli approximation for a number of the low lying triplets in O III. Special attention was given to the 2p3p 3P-2p3d 3P transition which is a primary cascade for the Bowen fluorescence mechanism in O III. The relativistic, largely spin-orbit, effect on the intensity ratio of primary decays was found to be as large as 50%, whereas the effect on secondary cascades was less than 30%. Agreement with astrophysically observed intensity ratios is excellent. There also is good agreement between the present liftimes and the beam-foil mean lifetimes obtained by Pinnington et al., though for 2p3p 3D and 3S the theoretical lifetimes are considerably shorter.

The dielectric response of Gd3+ ion-doped PbWO4 single crystal in wide temperature and frequency ranges was measured and a new dielectric relaxation phenomenon relative to oxygen ion was observed during the cooling process. With experimental results of X-ray photoelectron spectroscopy (XPS), the existence of interstitial oxygen ions was verified in Gd-doped crystals.

We demonstrate the improvement of device lifetime by organic light-emitting devices with an iodogallium phthalocyanine (IGaPc) layer fabricated on indium tin oxide (ITO) treated with positive oxygen ions. The device performance improves markedly as follows: (a) long-term stability (an operational half-lifetime of 100 h at high current density of 100 mA/cm2), and (b) the driving voltage is unchanged. The change in the device characteristics is attributed to changes in IGaPc molecular configurations during the growth process, leading to enhanced hole injection from the ITO to IGaPc layer.

A method is presented to estimate the densities of He-like carbon and oxygen ionsfrom the observation of the Li-like 3p + 3s transitions inthe visible and the 3p + 2s transitionsin the vacuum ulbav ...

Preparation of extremely low-resistivity contacts (10-9 Ω cm2) to the surface of bi-axially oriented high-temperature superconductor thin films is achieved. The low-resistivity contacts were made at the surfaces of Cu1-xTlxBaSrCa2Cu2O8-y (Cu1-xTlx-1212), Cu1-xTlxBaSrCa2Cu3O10-y (Cu1-xTlx-1223) and Cu1-xTlxBa2Ca2Cu3O12-y (Cu1-xTlx-1234) superconductor thin films (Khan et al 1999 Physica C 320 39). The results of contact formation at the surface of Cu1-xTlx-1223 thin films are presented in this paper. The parameters investigated in order to produced low-resistivity contacts were oxygen ion etching, sputtering conditions, the post-deposition annealing temperature and the ambient (air or O2) during annealing. It was found that post-annealing in air at 500 °C after sputter deposition were the optimal conditions for low-resistivity contacts (10-9 Ω cm2).

The charge transfer cross sections of Li+ (1s2) ions in collisions with B5+, C6+, N5+ (1s2), and O6+ (1s2) ions, and of Li2+ (1s) ions with Be+ (1s22s) ions are calculated in the collision energy range of 0.02–32 keV/amu by using a semi-classical close-coupling method with molecular-state expansion.

By detecting 0.2-1 MeV carbon and oxygen ions, Rutherford backscattered off a gold target, using a silicon surface barrier detector, it has been possible to demonstrate that, for these ions and energies, the detection efficiency is 100%.

The confining potential and the wave functions of the oxygen anion in the step on the (001) surface of MgO are calculated from first principles. The confining potential is found strong enough for the O-2 anion in the step to be stable. The method is described and the calculated potential and wave functions are given.

RF SQUIDs have been made from epitaxial YBCO films. The films were patterned by standard photolithography and wet chemical etching. The SQUIDs used S-N-S 'monolithic' weak link produced by oxygen ion irradiation, through a slit in a PMMA mask across the microbridge made by electron beam lithography. Changing the slit dimensions and irradiation dose, it was possible to observe proper SQUID function up to temperatures as high as 80 K.

It is shown that negative ions can be ejected from gas-phase water molecules when bombarded with positive ions at keV energies. Emission of both H− and heavier (O− and OH−) anions is observed. Electronic excitation and ionization processes are shown to play a decisive role in cation-induced anion formation.

We report the angular distribution of the fragment ions formed in the collision of Xe9+ ions with isolated water molecules. A significant anisotropy, and strong alignment effects have been seen. It is observed that there is a strong forward - backward asymmetry in the emission of protons and oxygen ions in the three body dissociation of multiply charged water molecules.

A mixed-NiOx/NiOy-film-based unipolar-type resistive switching memory device is proposed and fabricated. Mixed NiOx/NiOy films were prepared by two-step film deposition followed by furnace annealing. Mixed phases of Ni2O3 and NiO coexist across the mixed NiOx/NiOy films. Compared with a single-NiOy-film-based memory device, the mixed-NiOx/NiOy-film-based memory device shows improved unipolar resistive switching performances, including high ON/OFF ratio, sufficient operation voltage window, and good endurance characteristics. The improved memory performance could be attributed to the effect of oxygen-rich NiOx with more oxygen-rich Ni2O3, which can supply sufficient oxygen ions (O2−) for resistive switching in mixed-NiOx/NiOy-film-based resistive random access memory (RRAM) devices.

In this work, we investigate the characteristics of ZnO resistive random access memory (RRAM) with a reduced graphene oxide (rGO) capping layer and the polarity effect of the SET/RESET bias on the RRAM. The rGO film insertion enhances the stability of the current–voltage (I–V) switching curve and the superior resistance ratio (~105) of high-resistance state (HRS) to low-resistance state (LRS). Using the appropriate polarity of the SET/RESET bias applied to the rGO-capped ZnO RRAM enables the oxygen ions to move mainly at the interface of the rGO and ZnO films, resulting in the best performance. Presumably, the rGO film acts as an oxygen reservoir and enhances the easy in and out motion of the oxygen ions from the rGO film. The rGO film also prevents the interaction of oxygen ions and the Al electrode, resulting in excellent performance. In a pulse endurance test, the rGO-capped ZnO RRAM reveals superior endurance of up to 108 cycles over that of the ZnO RRAM without rGO insertion (106 cycles).

The resonance positions and total and partial widths of some 2s+1L° doubly excited autoionizing states of helium-like oxygen ions O6+ converging on n = 3 and n = 4 hydrogenic thresholds are reported for L = 1, 2, 3, 4 and 5. The calculation was made in the framework of the diagonalisation method approximation in the LS coupling scheme. The partial widths for multi-channel autoionizing levels to sublevels of O7+ were calculated by neglecting the direct coupling between the open channels.

The effect of transparent conductive oxide TCO buffer layer on the insulator matrix and on the resistive switching process in the metal TiO2 TCO metal assembly was studied depending on the material of TCO ITO In2O3 0.9 SnO2 0.1 or SnO2 or ZnO . First time electro physical studies and near edge x ray absorption fine structure NEXAFS studies were carried out jointly and in the same point of the sample providing the direct experimental evidence that switching process influences strongly the lowest unoccupied bands and local atomic structure of the TiO2 layers. It was established that TCO layer in metal TiO2 TCO metal assembly is an additional source of oxygen vacancies for TiO2 film. The RL RH states are achieved presumably with formation rupture of electrically conductive path of oxygen vacancies. The inserting the Al2O3 thin layer between TiO2 and TCO layers restricts to some extent processes of migration of oxygen ions and vacancies and does not permit to realize the anti clockwise bipolar resistive switching in Au TiO2 Al2O3 ITO Au assembly. The greatest value of the ratio RH RL is observed for assembly with SnO2 buffer layer that will provide to implement the maximum set of intermediate states recording analog data and increases the density of information recording in this case

Absolute cross sections for positive and negative ion fragments formed from O2 molecules following collisions with H+, H2+, He+, and Ar+ projectiles in the energy range 50–350 keV are presented. Cross sections for negatively charged secondary ions are much smaller ( cm2) compared to those for positively charged fragments. The non-dissociative formation of negatively charged O2− ions results from an electron transfer collision with the projectile. The impact energy dependence shows that the collision cross section for O2− formation strongly depends on the type of projectile involved.

We measure the transmission of medium energy O6+ ions through a tapered macro-glass capillary with a diameter of 0.2mm at the exit. The results show that the defection angles are smaller than the tilt angles, i.e., the ions propagate the capillary unparalleled to its axis, leading to a partial-guiding effect.

We study the guiding effect of 900 keV O6+ through a single macro-capillary with two incident currents of 0.06 nA and 3.00 nA, which is independent on the incident current.

During the sputtering process, the bombardment effect of negative oxygen ions (NOIs) on the thin-film properties of amorphous indium gallium zinc oxide (a-IGZO) was investigated. The energies of NOIs determined by in situ ion energy analyses are in good agreement with the values obtained using the Meyer equation. Furthermore, we find that the energies of NOIs are sufficiently high to affect the lattice distortion and/or displacement in a-IGZO films. The overall analysis revealed that the bombardment of NOIs has a considerable effect on a-IGZO film properties. Our work demonstrates that the bombardment of NOIs is a crucial issue for achieving high-quality a-IGZO films.

Dense melt processed Bi2Sr2CaCu2O8 superconductor was irradiated below Tc with 400 MeV oxygen ions up to a dose of 3*1015 cm-2. After a dose of 1.5*1015 cm-2 the irreversible magnetization showed a marked increase at low temperatures, while the adverse effect of Tc reduction seemed to prevail for T>60 K; at 3*1015 cm-2 no further increase or even a decrease was observed. On the other hand the logarithmic time decay 1/M dM/d1n t remained nearly unchanged. Irradiation initially shifts the irreversibility line to higher fields followed by a subsequent drop after a dose of 3*1015 ions/cm-2.

The effects of substituting a potassium ion for a barium ion in barium phosphate on lattice parameters and proton migration were investigated using density functional theory. A proton inserted into the material preferred to be attached to an oxygen ion near the potassium ion to compensate for the positive charge of the potassium ion that is less than that of the barium ion. Lattice parameters were investigated as a function of the potassium ion concentration. The lattice parameter a increased linearly with the potassium ion concentration, while the lattice parameter c remained almost constant. These trends were in good agreement with the experimental results. When the proton migrated from the a b-plane containing the potassium ion to the plane free of the potassium ion, a high energy barrier of 0.58 eV was required for proton migration. This value was also in good agreement with the experimentally measured energy barriers (0.53–0.58 eV).

We report the enhanced silicon-vacancy (Si-V) photoluminescence (PL) intensity and n-type conductivity of ultrananocrystalline diamond (UNCD) films by oxygen ion (O+) implantation. With O+ dose increasing from 1014 to 1015 cm−2, the PL intensity and n-type conductivity significantly increase by 6 and 45 times, respectively, after 1000°C annealing. The secondary ion mass spectroscopy mapping measurements show that the content of oxygen is larger in the zone, which has larger content of silicon, indicating that oxygen tends to adhere to silicon. It is suggested that oxygen related Si-V defects are formed, which will enhance the PL intensity and n-type conductivity of UNCD films.

We propose and investigate a metal oxide heterostructure (MOH) based resistive switching (RS) device. The driving mechanism of resistive switching (RS) in an MOH is more directly related to oxygen ion/vacancy migration around their interface. The performance of an MOH-based RS device depends on the oxygen mobility, oxygen vacancy concentration as well as its relation to the resistivity. An enhanced ratio of high resistance state to low resistance state can be achieved if the two involved metal oxides are mutually complemental metal oxides in which one of them has larger resistivity with increasing concentration of vacancy while the other one is the reverse.

Exchange bias effects in CoO/Co bilayers fabricated by ion-assisted deposition were studied as a function of CoO thickness. During the deposition of the top CoO layer, pillar-like CoO structures were embedded in the underlying Co layer due to implantation of oxygen ions. The enhanced coercivity was attributed to the changes in the magnetic reversal mechanism in the ferromagnetic Co layer due to the penetration of pillar-like structures of antiferromagnetic CoO. At low temperature, we found a strong exchange bias field. Our measurements indicate that the exchange bias effect can exist in a nanocomposite system that has a disordered mixture of columnar and planar Co/CoO interfaces.

The interaction effect of two protons on their migration in bulk barium zirconate was investigated to understand the difference between experimental and calculated energy barriers for proton migration using density functional theory. There were four different proton structure configurations in terms of proton interaction distance; symmetrically distorted, undistorted, symmetrically/asymmetrically distorted, and asymmetrically distorted. The asymmetrically distorted structure was obtained with the shortest distance between the two protons and was energetically the most stable. A high energy barrier of 0.41 eV was required for proton migration when a proton migrated near another proton owing to their repulsive interaction with each other and attractive interaction with neighboring oxygen ions. Therefore, the interaction between protons can contribute to reducing the difference between experimental and calculated energy barriers for proton migration in bulk barium zirconate.

This article reviews the polarizability model and its applications to ferroelectric perovskite oxides. The motivation for the introduction of the model is discussed and nonlinear oxygen ion polarizability effects and their lattice dynamical implementation outlined. While a large part of this work is dedicated to results obtained within the self-consistent-phonon approximation (SPA), also nonlinear solutions of the model are handled which are of interest to the physics of relaxor ferroelectrics, domain wall motions, incommensurate phase transitions. The main emphasis is to compare the results of the model with experimental data and to predict novel phenomena., Comment: 55 pages, 35 figures