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Sample records for bifeo3 thin films

  1. Nanoscale Control of Exchange Bias with BiFeO3 Thin Films

    NARCIS (Netherlands)

    Martin, Lane W.; Chu, Ying-Hao; Holcomb, Mikel B.; Huijben, Mark; Yu, Pu; Han, Shu-Jen; Lee, Donkoun; Wang, Shan X.; Ramesh, R.

    2008-01-01

    We demonstrate a direct correlation between the domain structure of multiferroic BiFeO3 thin films and exchange bias of Co0.9Fe0.1/BiFeO3 heterostructures. Two distinct types of interactions − an enhancement of the coercive field (exchange enhancement) and an enhancement of the coercive field combin

  2. Preparation of La-doped BiFeO3 Thin Film and Its Photovoltaic Properties

    Directory of Open Access Journals (Sweden)

    XIE Yi-Jun, GUO Yi-Ping, DONG Wen, GUO Bing, LI Hua, LIU He-Zhou

    2013-04-01

    Full Text Available The La3+ doped BiFeO3 (BFO thin films were fabricated by Sol-Gel method. The precursor solution was synthesized by dissolving Bi(NO33, Fe(NO33 and La(NO33 in 2-methoxyethanol and BiFeO3 thin films were grown by chemical solution deposition on fluorine doped tin oxide (FTO glass substrate. The influence of La3+ doping on the band gap and photovoltaic properties of BiFeO3 was studied. The BiFeO3 thin films exhibited polycrystalline-phase perovskite structure. The lattice parameter of BiFeO3 decreased with La3+ addition increasing. The band gap of BiFeO3 doped with 10% La3+ doping was 2.71 eV, a little smaller than that of the undoped one. The bandgap of BiFeO3 increased to 2.76 eV with the increase of La3+ doping. The maximal open circuit voltage of 10% La3+-doped BiFeO3 prepared by modified method reached 0.4 V, showing good photovoltaic properties.

  3. Atomic Structure of Highly Strained BiFeO3 Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Rossell, M.D. [Lawrence Berkeley National Laboratory (LBNL); Erni, R. [Lawrence Berkeley National Laboratory (LBNL); Prange, Micah P [ORNL; Idrobo Tapia, Juan C [ORNL; Luo, Weidong [ORNL; Zeches, R J [University of California, Berkeley; Pantelides, Sokrates T [ORNL; Ramesh, R [Lawrence Berkeley National Laboratory (LBNL)

    2012-01-01

    We determine the atomic structure of the pseudotetragonal T phase and the pseudorhombohedral R phase in highly strained multiferroic BiFeO3 thin films by using a combination of atomic-resolution scanning transmission electron microscopy and electron energy-loss spectroscopy. The coordination of the Fe atoms and their displacement relative to the O and Bi positions are assessed by direct imaging. These observations allow us to interpret the electronic structure data derived from electron energy-loss spectroscopy and provide evidence for the giant spontaneous polarization in strained BiFeO3 thin films.

  4. Epitaxial ferroelectric BiFeO3 thin films for unassisted photocatalytic water splitting

    Science.gov (United States)

    Ji, Wei; Yao, Kui; Lim, Yee-Fun; Liang, Yung C.; Suwardi, Ady

    2013-08-01

    Considering energy band alignment and polarization effect, ferroelectric BiFeO3 thin films are proposed as the photoanode in a monolithic cell to achieve unassisted photocatalytic water splitting. Significant anodic photocurrent was observed in our epitaxial ferroelectric BiFeO3 films prepared from sputter deposition. Both negative polarization charges and thinner films were found to promote the anodic photocatalytic reaction. Ultraviolet photoelectron spectroscopy proved that the conduction and valence band edges of BiFeO3 straddle the water redox levels. Theoretical analyses show that the large switchable polarization can modify the surface properties to promote the hydrogen and oxygen evolutions on the surfaces with positive and negative polarization charges, respectively.

  5. Epitaxial ferroelectric BiFeO3 thin films for unassisted photocatalytic water splitting

    International Nuclear Information System (INIS)

    Considering energy band alignment and polarization effect, ferroelectric BiFeO3 thin films are proposed as the photoanode in a monolithic cell to achieve unassisted photocatalytic water splitting. Significant anodic photocurrent was observed in our epitaxial ferroelectric BiFeO3 films prepared from sputter deposition. Both negative polarization charges and thinner films were found to promote the anodic photocatalytic reaction. Ultraviolet photoelectron spectroscopy proved that the conduction and valence band edges of BiFeO3 straddle the water redox levels. Theoretical analyses show that the large switchable polarization can modify the surface properties to promote the hydrogen and oxygen evolutions on the surfaces with positive and negative polarization charges, respectively

  6. Nanoscale control of exchange bias with BiFeO3 thin films

    OpenAIRE

    Martin, Lane W.; Chu, Ying-Hao; Mikel B. Holcomb; Huijben, Mark; Han, Shu-Jen; Lee, Donkoun; Wang, Shan X.; Ramesh, R.

    2008-01-01

    We demonstrate a direct correlation between the domain structure of multiferroic BiFeO3 thin films and exchange bias of Co0.9Fe0.1/BiFeO3 heterostructures. Two distinct types of interactions, an enhancement of the coercive field (exchange enhancement) and an enhancement of the coercive field combined with large shifts of the hysteresis loop (exchange bias), have been observed in these heterostructures, which depend directly on the type and crystallography of the nanoscale (2 nm) domain walls ...

  7. Optimization of excess Bi doping to enhance ferroic orders of spin casted BiFeO3 thin film

    International Nuclear Information System (INIS)

    Multiferroic Bismuth Ferrite (BiFeO3) thin films with varying excess bismuth (Bi) concentration were grown by chemical solution deposition technique. Room temperature multiferroic properties (ferromagnetism, ferroelectricity, and piezoelectricity) of the deposited BiFeO3 thin films have been studied. High resolution X-ray diffraction and Raman spectroscopy studies reveal that the dominant phases formed in the prepared samples change continuously from a mixture of BiFeO3 and Fe2O3 to pure BiFeO3 phase and, subsequently, to a mixture of BiFeO3 and Bi2O3 with increase in the concentration of excess Bi from 0% to 15%. BiFeO3 thin films having low content (0% and 2%) of excess Bi showed the traces of ferromagnetic phase (γ-Fe2O3). Deterioration in ferroic properties of BiFeO3 thin films is also observed when prepared with higher content (15%) of excess Bi. Single-phased BiFeO3 thin film prepared with 5% excess Bi concentration exhibited the soft ferromagnetic hysteresis loops and ferroelectric characteristics with remnant polarization 4.2 μC/cm2 and saturation magnetization 11.66 emu/g. The switching of fine spontaneous domains with applied dc bias has been observed using piezoresponse force microscopy in BiFeO3 thin films having 5% excess Bi. The results are important to identify optimum excess Bi concentration needed for the formation of single phase BiFeO3 thin films exhibiting the improved multiferroic properties.

  8. 180° Ferroelectric Stripe Nanodomains in BiFeO3 Thin Films.

    Science.gov (United States)

    Chen, Zuhuang; Liu, Jian; Qi, Yajun; Chen, Deyang; Hsu, Shang-Lin; Damodaran, Anoop R; He, Xiaoqing; N'Diaye, Alpha T; Rockett, Angus; Martin, Lane W

    2015-10-14

    There is growing evidence that domain walls in ferroics can possess emergent properties that are absent in the bulk. For example, 180° ferroelectric domain walls in the ferroelectric-antiferromagnetic BiFeO3 are particularly interesting because they have been predicted to possess a range of intriguing behaviors, including electronic conduction and enhanced magnetization. To date, however, ordered arrays of such domain structures have not been reported. Here, we report the observation of 180° stripe nanodomains in (110)-oriented BiFeO3 thin films grown on orthorhombic GdScO3 (010)O substrates and their impact on exchange coupling to metallic ferromagnets. Nanoscale ferroelectric 180° stripe domains with {112̅} domain walls were observed in films <32 nm thick. With increasing film thickness, we observed a domain structure crossover from the depolarization field-driven 180° stripe nanodomains to 71° ferroelastic domains determined by the elastic energy. These 180° domain walls (which are typically cylindrical or meandering in nature due to a lack of strong anisotropy associated with the energy of such walls) are found to be highly ordered. Additional studies of Co0.9Fe0.1/BiFeO3 heterostructures reveal exchange bias and exchange enhancement in heterostructures based on BiFeO3 with 180° domain walls and an absence of exchange bias in heterostructures based on BiFeO3 with 71° domain walls; suggesting that the 180° domain walls could be the possible source for pinned uncompensated spins that give rise to exchange bias. This is further confirmed by X-ray circular magnetic dichroism studies, which demonstrate that films with predominantly 180° domain walls have larger magnetization than those with primarily 71° domain walls. Our results could be useful to extract the structure of domain walls and to explore domain wall functionalities in BiFeO3. PMID:26317408

  9. Probing Ferroelectric Domain Engineering in BiFeO3 Thin Films by Second Harmonic Generation.

    Science.gov (United States)

    Trassin, Morgan; Luca, Gabriele De; Manz, Sebastian; Fiebig, Manfred

    2015-09-01

    An optical probe of the ferroelectric domain distribution and manipulation in BiFeO3 thin films is reported using optical second harmonic generation. A unique relation between the domain distribution and its integral symmetry is established. The ferroelectric signature is even resolved when the film is covered by a top electrode. The effect of voltage-induced ferroelectric switching is imaged. PMID:26175000

  10. Dielectric dynamics of epitaxial BiFeO3 thin films

    OpenAIRE

    Peng Ren; Peng Liu; Bin Xia; Xi Zou; Lu You; Junling Wang; Lan Wang

    2012-01-01

    We report the detailed study on the low temperature dielectric dynamics of the epitaxial BiFeO3 thin films grown on Nb-doped SrTiO3 substrate. The results indicate that the contributions from the thin film dominate the dielectric response, although it comes from both the thin film and the electrode interface. Furthermore, the origins of the low temperature dielectric anomalies are investigated with electric circuit fittings. A possible phase transition at 210 K is revealed from analysis with ...

  11. Conduction through 71 degrees DomainWalls in BiFeO3 Thin Films

    OpenAIRE

    Farokhipoor, S.; Noheda, Beatriz

    2011-01-01

    Local conduction at domains and domain walls is investigated in BiFeO3 thin films containing mostly 71 degrees domain walls. Measurements at room temperature reveal conduction through 71 degrees domain walls. Conduction through domains could also be observed at high enough temperatures. It is found that, despite the lower conductivity of the domains, both are governed by the same mechanisms: in the low voltage regime, electrons trapped at defect states are temperature activated but the curren...

  12. Memory and threshold resistive switching in BiFeO3 thin films using NiO as a buffer layer

    Science.gov (United States)

    Luo, Jinming; Zhang, Haining; Chen, Shuhan; Yang, Xiaodong; Bu, Shouliang; Wen, Jianping

    2016-05-01

    BiFeO3 and BiFeO3/NiO thin films have been deposited on Pt/Ti/SiO2/Si substrates by sol-gel method. Compared with bare BiFeO3 thin films, an improvement of memory resistive switching characteristic, such as the dispersion of switching voltages and resistances, has been clearly observed in BiFeO3 thin films using NiO as a buffer layer. Moreover, threshold resistive switching has also been demonstrated in BiFeO3/NiO thin films, but no observation in BiFeO3 thin films. Then, the role of thin NiO layer on memory resistive switching stabilization and threshold resistive switching is discussed.

  13. Influence of target composition and deposition temperature on the domain structure of BiFeO3 thin films

    Directory of Open Access Journals (Sweden)

    Rui Guo

    2012-12-01

    Full Text Available Domain structure of BiFeO3 thin films can be controlled by adjusting the target composition or the substrate temperature during pulsed laser deposition. Decreasing Bi content in the target or increasing substrate temperature changes the domain structure of BiFeO3 from 71° to 109°. We suggest that a combination of interface effect and defect induced internal field causes this evolution.

  14. Screening effects in ferroelectric resistive switching of BiFeO3 thin films

    Directory of Open Access Journals (Sweden)

    S. Farokhipoor

    2014-05-01

    Full Text Available We investigate ferroelectric resistive switching in BiFeO3 thin films by performing local conductivity measurements. By comparing conduction characteristics at artificially up-polarized domains with those at as-grown down-polarized domains, the change in resistance is attributed to the modification of the electronic barrier height at the interface with the electrodes, upon the reversal of the electrical polarization. We also study the effect of oxygen vacancies on the observed conduction and we propose the existence of a different screening mechanism for up and down polarized domains.

  15. Dielectric dynamics of epitaxial BiFeO3 thin films

    Directory of Open Access Journals (Sweden)

    Peng Ren

    2012-06-01

    Full Text Available We report the detailed study on the low temperature dielectric dynamics of the epitaxial BiFeO3 thin films grown on Nb-doped SrTiO3 substrate. The results indicate that the contributions from the thin film dominate the dielectric response, although it comes from both the thin film and the electrode interface. Furthermore, the origins of the low temperature dielectric anomalies are investigated with electric circuit fittings. A possible phase transition at 210 K is revealed from analysis with dielectric loss tangent. The dielectric constants obtained from the constant phase elements (CPEs are more than 400 even at low temperatures. Finally, the physical significances of the CPE model are discussed.

  16. Fatigue and ferroelectric behavior of La and Zn comodified BiFeO3 thin films

    International Nuclear Information System (INIS)

    Bi0.90La0.10Fe0.95Zn0.05O3 (BLFZO) thin films were grown directly on Pt/TiO2/SiO2/Si(100) substrates without any buffer layer by off-axis radio frequency sputtering. The BLFZO thin film deposited at 580 deg. C possesses a single-phase purity, while those deposited at other temperatures exhibit a varying amount of second phases, indicating that the deposition temperature plays a critical role in the phase development of BLFZO thin films. Although La and Zn cosubstitutions lower the Curie temperature (Tc) of BiFeO3 thin films, the resulting Tc value (∼630 deg. C) is still much higher as compared to other lead-based or lead-free ferroelectric thin films. The BLFZO thin film exhibits a remanent polarization of 2Pr∼131.7 μC/cm2 and a coercive field of 2Ec∼496 kV/cm, in association with the improvement in electrical resistance. On the basis of the studies for frequency (1 kHz∼1 MHz) and driving field (0.8Ec∼2.0Ec) dependences, the BLFZO thin film demonstrates the desired fatigue endurance and weak frequency and driving field dependence. La and Zn cosubstitutions are shown to contribute toward the high remanent polarization and fatigue endurance.

  17. Leakage mechanism of cation -modified BiFeO3 thin film

    Directory of Open Access Journals (Sweden)

    Jiagang Wu

    2011-06-01

    Full Text Available To investigate the leakage mechanisms in cation -substituted BiFeO3 (BFO thin films, in Bi site or Fe site or both sites, Bi0.92La0.08FeO3, BiFe0.95Mn0.05O3, and Bi0.92La0.08Fe0.95Mn0.05O3 thin films were grown in situ by radio frequency magnetic sputtering on SrRuO3/SrTiO3(111 substrates, where the (111 orientation is established in all thin films. The variation in cation substitution results in different leakage behavior of BFO thin films. Space charge limited conduction and a grain boundary limited behavior are responsible for the leakage behavior of Bi0.92La0.08FeO3 and BiFe0.95Mn0.05O3 thin films in a low electric field region, respectively, while an interface-limited Fowler-Nordheim tunneling is involved in their leakage behavior in a high electric field region. In contrast, the leakage of Bi0.92La0.08Fe0.95Mn0.05O3 endures a transition from an Ohmic conduction to space charge limited conduction with increasing electric fields. The three thin films however show little temperature dependence of the leakage behavior in the temperature range investigated.

  18. Enhanced photovoltaic properties in bilayer BiFeO3/Bi-Mn-O thin films

    Science.gov (United States)

    Chakrabartty, Joyprokash; Nechache, Riad; Harnagea, Catalin; Li, Shun; Rosei, Federico

    2016-05-01

    We report an external solar power conversion efficiency of ∼1.43% in BiFeO3(BFO)/BiMnO3(BMO) bilayer thin films. Both films are epitaxially grown on (111) oriented niobium doped SrTiO3 (NSTO) single crystal substrates by pulsed laser deposition. By illuminating the BFO/BMO films under 1 Sun (AM 1.5 G), we found a remarkably high fill factor of ∼0.72, much higher than values reported for devices based on BFO or BMO alone. In addition, we demonstrate that the photocurrent density and photovoltage are tunable by changing the polarization direction in the BFO/BMO bilayer, as confirmed by the macroscopic polarization–voltage (P–V) hysteresis loop. This effect is described in terms of a more favorable energy band alignment of the electrode/bilayer/NSTO heterostructure junction, which controls photocarrier separation.

  19. Enhanced photovoltaic properties in bilayer BiFeO3/Bi-Mn-O thin films.

    Science.gov (United States)

    Chakrabartty, Joyprokash; Nechache, Riad; Harnagea, Catalin; Li, Shun; Rosei, Federico

    2016-05-27

    We report an external solar power conversion efficiency of ∼1.43% in BiFeO3(BFO)/BiMnO3(BMO) bilayer thin films. Both films are epitaxially grown on (111) oriented niobium doped SrTiO3 (NSTO) single crystal substrates by pulsed laser deposition. By illuminating the BFO/BMO films under 1 Sun (AM 1.5 G), we found a remarkably high fill factor of ∼0.72, much higher than values reported for devices based on BFO or BMO alone. In addition, we demonstrate that the photocurrent density and photovoltage are tunable by changing the polarization direction in the BFO/BMO bilayer, as confirmed by the macroscopic polarization-voltage (P-V) hysteresis loop. This effect is described in terms of a more favorable energy band alignment of the electrode/bilayer/NSTO heterostructure junction, which controls photocarrier separation. PMID:27094952

  20. Polarization-tuned diode behaviour in multiferroic BiFeO3 thin films

    KAUST Repository

    Yao, Yingbang

    2012-12-28

    Asymmetric rectifying I-V behaviour of multiferroic BiFeO3 (BFO) thin films grown on transparent ITO-coated glass was quantitatively studied as a function of ferroelectric polarization. Different polarized states were established by unipolar or bipolar poling with various applied electric fields. The effects of polarization relaxation and fatigue on the currents were also investigated. We found that the conduction currents and the associated rectifications were controlled by the amplitude and direction of the polarization. We clearly observed the linear dependence of the current on the polarization. It is suggested that the space-charge-limited conduction and the charge injection at the Schottky interface between the film and the electrodes dominate the current. The electrically controlled rectifying behaviour observed in this study may be useful in nonvolatile resistance memory devices or tunable diodes. © 2013 IOP Publishing Ltd.

  1. Preparation and characterization of BiFeO3 thin films by the LPD on OH-functionalized organic SAMs

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    BiFeO3 (BFO) thin films were grown on OH-functionalized organic self-assembled monolayers (SAMs) via liquid-phase deposition (LPD) method at a temperature below 100°C. The BiFeO3 thin films were induced to synthesize on the OH-functionalized organic OTS monolayers prepared on hydroxylated glass substrate by self-assembling technique. The hydrophilic characteristic of the as-prepared OTS-SAMs was measured by contact angle tester. The crystal phase composition, microstructure and topography of the as-synthesized BFO thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy disperse spectroscopy (EDS) and atomic force microscope (AFM), respectively. Results show that compact and homogeneous BFO thin films can be formed on the OH-functionalized SAMs at low temperature.

  2. Ultrafast Terahertz Gating of the Polarization and Giant Nonlinear Optical Response in BiFeO3 Thin Films.

    Science.gov (United States)

    Chen, Frank; Goodfellow, John; Liu, Shi; Grinberg, Ilya; Hoffmann, Matthias C; Damodaran, Anoop R; Zhu, Yi; Zalden, Peter; Zhang, Xiaohang; Takeuchi, Ichiro; Rappe, Andrew M; Martin, Lane W; Wen, Haidan; Lindenberg, Aaron M

    2015-11-01

    Terahertz pulses are applied as an all-optical bias to ferroelectric thin-film BiFeO3 while monitoring the time-dependent ferroelectric polarization through its nonlinear optical response. Modulations in the intensity of the second harmonic light generated by the film correspond to on-off ratios of 220× gateable on femtosecond timescales. Polarization modulations comparable to the built-in static polarization are observed. PMID:26389651

  3. Origin of thickness dependence of structural phase transition temperatures in highly strained BiFeO3 thin films

    Science.gov (United States)

    Yang, Yongsoo; Beekman, Christianne; Siemons, Wolter; Schlepütz, Christian M.; Senabulya, Nancy; Clarke, Roy; Christen, Hans M.

    2016-03-01

    Two structural phase transitions are investigated in highly strained BiFeO3 thin films as a function of film thickness and temperature via synchrotron x-ray diffraction. Both transition temperatures (upon heating: monoclinic MC to monoclinic MA to tetragonal) decrease as the film becomes thinner. A film-substrate interface layer, evidenced by half-order peaks, contributes to this behavior, but at larger thicknesses (above a few nanometers), the temperature dependence results from electrostatic considerations akin to size effects in ferroelectric phase transitions, but observed here for structural phase transitions within the ferroelectric phase. For ultra-thin films, the tetragonal structure is stable to low temperatures.

  4. A phase transition close to room temperature in BiFeO3 thin films

    International Nuclear Information System (INIS)

    BiFeO3 (BFO) multiferroic oxide has a complex phase diagram that can be mapped by using appropriately substrate-induced strain in epitaxial films. By using Raman spectroscopy, we conclusively show that films of the so-called supertetragonal T-BFO phase, stabilized under compressive strain, display a reversible temperature-induced phase transition at about 100 deg. C, and thus close to room temperature. (fast track communication)

  5. The influence of Er, Ti co-doping on the multiferroic properties of BiFeO3 thin films

    Science.gov (United States)

    Ma, Yinina; Xing, Wenyu; Chen, Jieyu; Bai, Yulong; Zhao, Shifeng; Zhang, Hao

    2016-02-01

    The pure and Er, Ti co-doped BiFeO3 thin films were prepared by chemistry solution deposition. Enhanced ferroelectric and ferromagnetic properties were obtained, which is mainly attributed to that the effect of co-doping Er and Ti leads to the drastic crystal structural transformation from rhombohedral phase to orthorhombic phase. Thus crystal structural transformation not only changes the switching behavior of the polarization path to improve the ferroelectric polarization, but also suppresses the original spiral spin structure to release the locked magnetization. At the same time, the leakage current density is decreased after doping Er3+ and Ti4+, which results from that the crystal structural transformation changes the leakage current mechanism. The present work provides an available way on improving the multiferroic properties of BiFeO3 thin films.

  6. Interfacial-strain-induced structural and polarization evolutions in epitaxial multiferroic BiFeO3 (001) thin films.

    Science.gov (United States)

    Guo, Haizhong; Zhao, Ruiqiang; Jin, Kui-Juan; Gu, Lin; Xiao, Dongdong; Yang, Zhenzhong; Li, Xiaolong; Wang, Le; He, Xu; Gu, Junxing; Wan, Qian; Wang, Can; Lu, Huibin; Ge, Chen; He, Meng; Yang, Guozhen

    2015-02-01

    Varying the film thickness is a precise route to tune the interfacial strain to manipulate the properties of the multiferroic materials. Here, to explore the effects of the interfacial strain on the properties of the multiferroic BiFeO3 films, we investigated thickness-dependent structural and polarization evolutions of the BiFeO3 films. The epitaxial growth with an atomic stacking sequence of BiO/TiO2 at the interface was confirmed by scanning transmission electron microscopy. Combining X-ray diffraction experiments and first-principles calculations, a thickness-dependent structural evolution was observed from a fully strained tetragonality to a partially relaxed one without any structural phase transition or rotated twins. The tetragonality (c/a) of the BiFeO3 films increases as the film thickness decreases, while the polarization is in contrast with this trend, and the size effect including the depolarization field plays a crucial role in this contradiction in thinner films. These findings offer an alternative strategy to manipulate structural and polarization properties by tuning the interfacial strain in epitaxial multiferroic thin films. PMID:25580936

  7. Polycrystalline BiFeO3 thin film synthesized via sol-gel assisted spin coating technique for photosensitive application

    Science.gov (United States)

    Bogle, K. A.; Narwade, R. D.; Phatangare, A. B.; Dahiwale, S. S.; Mahabole, M. P.; Khairnar, R. S.

    2016-05-01

    We are reporting photosensitivity property of BiFeO3 thin film under optical illumination. The thin film used for photosensitivity work was fabricated via sol-gel assisted spin coating technique. I-V measurements on the Cu/BiFeO3/Al structure under dark condition show a good rectifying property and show dramatic blue shit in threshold voltage under optical illumination. The microstructure, morphology and elemental analysis of the films were characterized by using XRD, UV-Vis, FTIR, SEM and EDS.

  8. Intrinsic defect-mediated conduction and resistive switching in multiferroic BiFeO3 thin films epitaxially grown on SrRuO3 bottom electrodes

    Science.gov (United States)

    Lee, Ji Hye; Jeon, Ji Hoon; Yoon, Chansoo; Lee, Sangik; Kim, Yeon Soo; Oh, Tae Joon; Kim, Young Heon; Park, Jinsu; Song, Tae Kwon; Park, Bae Ho

    2016-03-01

    We report the impact of intrinsic defects in epitaxial BiFeO3 films on charge conduction and resistive switching of Pt/BiFeO3/SrRuO3 capacitors, although the BiFeO3 films show very similar ferroelectric domain types probed by piezoresponse force microscopy. Capacitors with p-type Bi-deficient and n-type Bi-rich BiFeO3 films exhibit switchable diode and conventional bipolar resistive switching behaviors, respectively. Both the capacitors show good retention properties with a high ON/OFF ratio of >100 in Bi-deficient films and that of >1000 in Bi-rich films. The present investigation advances considerably understanding of interface control through defect engineering of BiFeO3 thin films for non-volatile memory application.

  9. Local conductivity and the role of vacancies around twin walls of (001)-BiFeO3 thin films

    OpenAIRE

    Farokhipoor, S.; Noheda, Beatriz

    2011-01-01

    BiFeO3 thin films epitaxially grown on SrRuO3-buffered (001)-oriented SrTiO3 substrates show orthogonal bundles of twin domains, each of which contains parallel and periodic 71 degrees domain walls. A smaller amount of 109 degrees domain walls are also present at the boundaries between two adjacent bundles. All as-grown twin walls display enhanced conductivity with respect to the domains during local probe measurements, due to the selective lowering of the Schottky barrier between the film an...

  10. Ultrafast carrier dynamics and radiative recombination in multiferroic BiFeO3 single crystals and thin films

    Directory of Open Access Journals (Sweden)

    Taylor A. J.

    2013-03-01

    Full Text Available We report a detailed comparison of ultrafast carrier dynamics in single crystals and thin films of multiferroic BiFeO3 (BFO. Using degenerate femtosecond optical pump-probe spectroscopy, we find that the observed dynamics are qualitatively similar in both samples. After photoexcitation, electrons relax to the conduction band minimum through electron-phonon coupling, with subsequent carrier relaxation proceeding via various recombination pathways that extend to a nanosecond timescale. Subtle differences observed in our measurements indicate that BFO films have a higher band gap than single crystals. Overall, our results demonstrate that carrier relaxation in BFO is analogous to that in bulk semiconductors.

  11. Giant optical enhancement of strain gradient in ferroelectric BiFeO3 thin films and its physical origin.

    Science.gov (United States)

    Li, Yuelin; Adamo, Carolina; Chen, Pice; Evans, Paul G; Nakhmanson, Serge M; Parker, William; Rowland, Clare E; Schaller, Richard D; Schlom, Darrell G; Walko, Donald A; Wen, Haidan; Zhang, Qingteng

    2015-01-01

    Through mapping of the spatiotemporal strain profile in ferroelectric BiFeO3 epitaxial thin films, we report an optically initiated dynamic enhancement of the strain gradient of 10(5)-10(6) m(-1) that lasts up to a few ns depending on the film thickness. Correlating with transient optical absorption measurements, the enhancement of the strain gradient is attributed to a piezoelectric effect driven by a transient screening field mediated by excitons. These findings not only demonstrate a new possible way of controlling the flexoelectric effect, but also reveal the important role of exciton dynamics in photostriction and photovoltaic effects in ferroelectrics. PMID:26586421

  12. Thickness-dependent piezoelectric behaviour and dielectric properties of lanthanum modified BiFeO3 thin films

    Directory of Open Access Journals (Sweden)

    Glenda Biasotto

    2011-03-01

    Full Text Available Bi0.85La0.15FeO3 (BLFO thin films were deposited on Pt(111/Ti/SiO2 /Si substrates by the soft chemical method. Films with thicknesses ranging from 140 to 280 nm were grown on platinum coated silicon substrates at 500°C for 2 hours. The X-ray diffraction analysis of BLFO films evidenced a hexagonal structure over the entire thickness range investigated. The grain size of the film changes as the number of the layers increases, indicating thickness dependence. It is found that the piezoelectric response is strongly influenced by the film thickness. It is shown that the properties of BiFeO3 thin films, such as lattice parameter, dielectric permittivity, piezoeletric coefficient etc., are functions of misfit strains.

  13. Origin of thickness dependence of structural phase transition temperatures in highly strained BiFeO3 thin films

    Directory of Open Access Journals (Sweden)

    Yongsoo Yang

    2016-03-01

    Full Text Available Two structural phase transitions are investigated in highly strained BiFeO3 thin films as a function of film thickness and temperature via synchrotron x-ray diffraction. Both transition temperatures (upon heating: monoclinic MC to monoclinic MA to tetragonal decrease as the film becomes thinner. A film-substrate interface layer, evidenced by half-order peaks, contributes to this behavior, but at larger thicknesses (above a few nanometers, the temperature dependence results from electrostatic considerations akin to size effects in ferroelectric phase transitions, but observed here for structural phase transitions within the ferroelectric phase. For ultra-thin films, the tetragonal structure is stable to low temperatures.

  14. Temperature controlled c axis elongated low symmetry phase BiFeO3 thin film on STO substrate

    Directory of Open Access Journals (Sweden)

    Peng Ren

    2013-01-01

    Full Text Available BiFeO3 thin films with a mixture of tunable R-like and c axis elongated low symmetry phase (T-like phase are fabricated on STO (001 substrate through controlling of the substrate temperature. Almost pure T-like phase can be grown on STO substrate at 600°C. Comparing with the situations on LAO (001, it is found that, strains from the LAO substrate may be the only reason that induces the T-like phase at higher temperatures. At lower temperatures, the island growth induced strains alone can also generate T-like phase on STO substrate.

  15. Enhanced electrical insulation and ferroelectricity in La and Ni co-doped BiFeO3 thin films

    International Nuclear Information System (INIS)

    Highlights: • La,Ni co-doped BiFeO3 thin films deposited by chemical solution method. • Polycrystalline films without any preferred orientation. • Bi0.95La0.05Fe0.975Ni0.025O3 sample shows a Pr of ∼66 μC/cm2 and a Ec of 0.3 MV/cm. • The lowest leakage for samples with co-doping of 5% La and 2.5% Ni. - Abstract: In this manuscript, we report the effect of co-doping of La and Ni in controlling the electrical leakage and enhancing the ferroelectric polarization in chemical solution processed BiFeO3 (BFO) thin films grown on Pt/Si substrates. Structural analysis of the films using X-ray diffraction shows that all the films are phase pure with perovskite structure and a R3c space group. The films are polycrystalline without evidence of any preferred orientation. Compared to the undoped BFO thin films, the leakage current in co-doped thin films is minimum at a La doping of 5 at% and Ni doping of 2.5 at% beyond which the leakage increases. While ferroelectric polarization does decrease marginally on co-doping, the shape of ferroelectric hysteresis loop improves in comparison to the undoped or singly doped films. The samples with La doping of 5 at% and Ni doping of 2.5 at% (Bi0.95La0.05Fe0.975Ni0.025O3) show a remnant polarization (Pr) of ∼66 μC/cm2 and a coercive field of 0.3 MV/cm at room temperature

  16. Microwave dielectric properties of BiFeO3 thin film prepared by aqueous chemical solution deposition method

    Directory of Open Access Journals (Sweden)

    Ričardas Sobiestianskas

    2009-12-01

    Full Text Available We report high frequency dielectric properties of multiferroic BiFeO3 (BFO thin film deposited by means of aqueous chemical solution deposition on platinized silicon substrate. The structure analysis of the BFO performed by X-ray diffraction and energy dispersive analysis showed pure, single-phase quality of the thin films. The impedance measurements were performed by vector network analyzer in frequency range 100 MHz to 10 GHz at ambient temperature. The film leakage currents dominate dielectric losses at low frequencies. The dielectric constant of the film is around 40. An internal charged defects acting as energy traps for electrons dominate dielectric losses in the frequency region above 4 GHz.

  17. Domain walls and their conduction properties in ferroelectric BiFeO3 thin films

    OpenAIRE

    Farokhipoor, Saeedeh

    2013-01-01

    Geleidingseigenschappen BiFeO3 onderzocht In haar proefschrift behandelt Saeedeh Farokhipoor geleidingseigenschappen van BiFeO3, een materiaal waarvan typisch isolerend gedrag verwacht mag worden. Het onderzoek naar BiFeO3 staat recent in de belangstelling. Het is namelijk één van de weinige materialen die bij kamertemperatuur een sterke materiaalrespons vertoont in zowel een aangelegd elektrisch- als een magnetisch veld. BiFeO3 kan in dunne lagen onder roosterspanning worden gegroeid op een ...

  18. Grain size and stoichiometry control over RF-sputtered multiferroic BiFeO3 thin films on silicon substrates

    International Nuclear Information System (INIS)

    This work reports the morphological and chemical characterization of multiferroic BiFeO3 polycrystalline thin films grown on Si(111) by RF-sputtering. Results are shown for a large set of samples and a wide array of experimental techniques, including imaging (atomic/piezoresponse force microscopy) and spectroscopic (μ-Raman, X-ray photoemission, X-ray diffraction) probes. Through growth and post-growth annealing treatment, a fine control over stoichiometry, grain size, grain orientation, crystal order and surface roughness is achieved. In particular, the grain size can be tailored from nanocrystals to large micrometric plates as a function of the annealing temperature. For the optimal stoichiometric sample, an additional X-ray absorption and magnetic circular dichroism analysis has been carried out, which provides high quality spectra comparable with epitaxial films and further proves the expected strong local antiferromagnetic order. - Highlights: • We show the growth of polycristalline multiferroic BiFeO3 on Si(111) by RF-sputtering. • Multi-technique (AFM/PFM,XPS,XRD,XAS,XMCD,Raman) characterization is given. • Crystal size, homogeneity and chemistry are tailored by growth or post-growth annealing. • In optimal conditions, piezoelectricity, ferroelectricity and magnetism are found

  19. Focused-ion-beam induced damage in thin films of complex oxide BiFeO3

    Directory of Open Access Journals (Sweden)

    W. Siemons

    2014-02-01

    Full Text Available An unexpected, strong deterioration of crystal quality is observed in epitaxial perovskite BiFeO3 films in which microscale features have been patterned by focused-ion-beam (FIB milling. Specifically, synchrotron x-ray microdiffraction shows that the damaged region extends to tens of μm, but does not result in measureable changes to morphology or stoichiometry. Therefore, this change would go undetected with standard laboratory equipment, but can significantly influence local material properties and must be taken into account when using a FIB to manufacture nanostructures. The damage is significantly reduced when a thin metallic layer is present on top of the film during the milling process, clearly indicating that the reduced crystallinity is caused by ion beam induced charging.

  20. Temperature dependence of the electronic transitions in BiFeO3 thin film studied by spectroscopic ellipsometry

    International Nuclear Information System (INIS)

    The temperature dependence of the electronic response of BiFeO3 thin film grown on a SrTiO3 substrate is investigated using spectroscopic ellipsometry. By analyzing the pseudodielectric function, we identify two d-d crystal field transitions of Fe3+ ions in the energy region between 1 and 2 eV. The d-d transitions show abnormal temperature dependence that cannot be attributed to conventional electron-phonon interactions. The origin of the abnormal temperature dependence is discussed in terms of spin-charge coupling. The temperature dependence of the charge transfer transitions located above 2.5 eV is characterized by standard critical point model analysis of the 2nd derivatives of the dielectric function. This analysis provides detailed information of the critical point parameters for charge transfer transitions

  1. Temperature dependences of ferroelectricity and resistive switching behavior of epitaxial BiFeO3 thin films

    Institute of Scientific and Technical Information of China (English)

    芦增星; 高兴森; 严志波; 刘俊明; 宋骁; 赵丽娜; 李忠文; 林远彬; 曾敏; 张璋; 陆旭兵; 吴素娟

    2015-01-01

    We investigate the resistive switching and ferroelectric polarization properties of high-quality epitaxial BiFeO3 thin films in various temperature ranges. The room temperature current–voltage (I–V ) curve exhibits a well-established polarization-modulated memristor behavior. At low temperatures (253 K), the I–V behaviors are governed by both space-charge-limited conduction (SCLC) and Ohmic behavior. The polarization reversal is able to trigger the conduc-tion switching from Ohmic to SCLC behavior, leading to the observed ferroelectric resistive switching. At a temperature of>298 K, there occurs a new resistive switching hysteresis at high bias voltages, which may be related to defect-mediated effects.

  2. Magnetic behaviour of sol-gel driven BiFeO3 thin films with different grain size distribution

    Science.gov (United States)

    Sharma, Shiwani; Saravanan, P.; Pandey, O. P.; Vinod, V. T. P.; Černík, Miroslav; Sharma, Puneet

    2016-03-01

    BiFeO3 (BFO) thin films with uniform thickness of ~200 nm were prepared by the sol-gel assisted spin coating method. Different grain size distributions in the as-grown BFO films were then induced by varying the annealing temperature between 525 and 600 °C. It is found that the grain size distribution become wider as the annealing temperature increases. All the films showed a well-saturated magnetization (M) versus magnetic field (H) hysteresis loops at 300 K. A strong dependence of M on the grain size distribution is observed. An optimal grain size distribution with average grain size ~90 nm is responsible for high M in the BFO films. The non-saturated M-H loops obtained at 10 K suggest the spin glass behaviour of BFO films. The zero field cooled (ZFC) and field cooled (FC) magnetization curves shows split at 300 K and a cusp at ~50 K in the ZFC curve, which further confirms the spin glass state of polycrystalline BFO thin films.

  3. Perovskite BiFeO3 thin film photocathode performance with visible light activity

    Science.gov (United States)

    Yilmaz, P.; Yeo, D.; Chang, H.; Loh, L.; Dunn, S.

    2016-08-01

    Perovskite materials are now an important class of materials in the application areas of photovoltaics and photocatalysis. Inorganic perovskites such as BiFeO3 (BFO) are promising photocatalyst materials with visible light activity and inherent stability. Here we report the large area sol-gel synthesis of BFO films for solar stimulated water photo oxidation. By modifying the sol-gel synthesis process we have produced a perovskite material that has p-type behaviour and a flat band potential of ∼1.15 V (versus NHE). The photocathode produces a density of ‑0.004 mA cm‑2 at 0 V versus NHE under AM1.5 G illumination. We further show that 0.6 μmol h‑1 of O2 was produced at an external bias of ‑0.5 V versus Ag/AgCl. The addition of a non-percolating conducting network of Ag increases the photocurrent to ‑0.07 mA cm‑2 at 0 V versus NHE (at 2% Ag loading) with an increase to 2.7 μmol h‑1 for O2 production. We attribute the enhancement in photoelectrochemical performance to increased light absorption due light scattering by the incorporated Ag particles, improved charge transfer kinetics at the Ag/BFO interface and reduced over potential losses. We support these claims by an observed shift in flat band and onset potentials after Ag modification through UV–vis spectroscopy, Mott–Schottky plots and j–v curve analysis.

  4. Perovskite BiFeO3 thin film photocathode performance with visible light activity.

    Science.gov (United States)

    Yilmaz, P; Yeo, D; Chang, H; Loh, L; Dunn, S

    2016-08-26

    Perovskite materials are now an important class of materials in the application areas of photovoltaics and photocatalysis. Inorganic perovskites such as BiFeO3 (BFO) are promising photocatalyst materials with visible light activity and inherent stability. Here we report the large area sol-gel synthesis of BFO films for solar stimulated water photo oxidation. By modifying the sol-gel synthesis process we have produced a perovskite material that has p-type behaviour and a flat band potential of ∼1.15 V (versus NHE). The photocathode produces a density of -0.004 mA cm(-2) at 0 V versus NHE under AM1.5 G illumination. We further show that 0.6 μmol h(-1) of O2 was produced at an external bias of -0.5 V versus Ag/AgCl. The addition of a non-percolating conducting network of Ag increases the photocurrent to -0.07 mA cm(-2) at 0 V versus NHE (at 2% Ag loading) with an increase to 2.7 μmol h(-1) for O2 production. We attribute the enhancement in photoelectrochemical performance to increased light absorption due light scattering by the incorporated Ag particles, improved charge transfer kinetics at the Ag/BFO interface and reduced over potential losses. We support these claims by an observed shift in flat band and onset potentials after Ag modification through UV-vis spectroscopy, Mott-Schottky plots and j-v curve analysis. PMID:27420393

  5. Engineering interface-type resistive switching in BiFeO3 thin film switches by Ti implantation of bottom electrodes.

    Science.gov (United States)

    You, Tiangui; Ou, Xin; Niu, Gang; Bärwolf, Florian; Li, Guodong; Du, Nan; Bürger, Danilo; Skorupa, Ilona; Jia, Qi; Yu, Wenjie; Wang, Xi; Schmidt, Oliver G; Schmidt, Heidemarie

    2015-01-01

    BiFeO3 based MIM structures with Ti-implanted Pt bottom electrodes and Au top electrodes have been fabricated on Sapphire substrates. The resulting metal-insulator-metal (MIM) structures show bipolar resistive switching without an electroforming process. It is evidenced that during the BiFeO3 thin film growth Ti diffuses into the BiFeO3 layer. The diffused Ti effectively traps and releases oxygen vacancies and consequently stabilizes the resistive switching in BiFeO3 MIM structures. Therefore, using Ti implantation of the bottom electrode, the retention performance can be greatly improved with increasing Ti fluence. For the used raster-scanned Ti implantation the lateral Ti distribution is not homogeneous enough and endurance slightly degrades with Ti fluence. The local resistive switching investigated by current sensing atomic force microscopy suggests the capability of down-scaling the resistive switching cell to one BiFeO3 grain size by local Ti implantation of the bottom electrode. PMID:26692104

  6. Optical and grain boundary potential characteristics of sulfurized BiFeO3 thin films for photovoltaic applications.

    Science.gov (United States)

    Lee, Seung Min; Cho, Yong Soo

    2016-04-01

    Sulfurized BiFeO3 (BFO) thin films have been investigated with the purpose of reducing their band gap for photovoltaic applications. A strong dependence of the degree of sulfurization on the structure and optical properties of the BFO thin films was observed. The sulfurization process substantially reduced the optical band gap from 2.83 eV for the reference sample to ∼1.90 eV in a sample sulfurized at 200 °C, a temperature at which the BFO phase was still dominant. The existence of the secondary Bi2S3 phase was found to be initiated from the film surface and became dominant at higher temperatures. XPS analysis suggests potential Bi-Fe(iii)-Fe(ii)-S-O compounds as a result of the change of the oxidation state of Fe with the progress of sulfurization. The sulfurized BFO film exhibited relatively higher positively charged grain boundaries than the reference film, suggesting its improved applicability in photovoltaic devices. PMID:26918247

  7. Swift heavy ion irradiation induced modification of structure and surface morphology of BiFeO3 thin film

    Indian Academy of Sciences (India)

    B N Dash; P Mallick; P Dash; R Biswal; Jai Prakash; A Tripathi; D Kanjilal; N C Mishra

    2013-10-01

    BiFeO3 (BFO) thin films of thickness about 800 nm deposited on Si (100) substrates by sol–gel spin coating method were irradiated by 200 MeV Ag ions. Modification of structure and surface morphology of the films under irradiation was studied using glancing incidence X-ray diffraction (GIXRD) and atomic force microscope (AFM). Fluence dependence of GIXRD peak intensity indicated formation of 10 nm diameter cylindrical amorphous columns in crystalline BFO due to 200 MeV Ag ion irradiation. AFM analysis indicated that the pristine film consists of agglomerated grains with diffuse grain boundary. Irradiation led to reduced agglomeration of the grains with the formation of sharper grain boundaries. The rms roughness (rms) estimated from AFM analysis increased from 6.2 in pristine film to 12.7 nm when the film irradiated at a fluence of 1 × 1011 ions cm-2. Further irradiation led to decrease of rms which finally saturated at a value of 7–8 nm at high ion fluences. The power spectral density analysis indicated that the evolution of surface morphology of the pristine film is governed by the combined effect of evaporation condensation and volume diffusion processes. Swift heavy ion irradiation seems to increase the dominance of volume diffusion in controlling surface morphology of the film at high ion fluences.

  8. Induced ferromagnetism and magnetoelectric coupling in ion-beam synthesized BiFeO3–CoFe2O4 nanocomposite thin films

    Science.gov (United States)

    Modarresi, H.; Lazenka, V.; Menéndez, E.; Lorenz, M.; Bisht, M.; Volodin, A.; Van Haesendonck, C.; Grundmann, M.; Van Bael, M. J.; Temst, K.; Vantomme, A.

    2016-08-01

    Ferrimagnetic CoFe2O4 (cobalt ferrite) is formed within an epitaxial BiFeO3 (bismuth ferrite) thin film matrix by Co channeled ion implantation and subsequent annealing. The presence of nanoscale CoFe2O4 crystals in the matrix is confirmed by x-ray diffraction using synchrotron radiation. The significantly increased magnetic moment and the low-temperature coercive field of the composite system evidence the formation of ferrimagnetic cobalt ferrite and its nanoscale character, respectively. The results demonstrate that ion beam synthesis is an appropriate method to controllably transform a planar system into a granular one, increasing the interface area between cobalt ferrite and bismuth ferrite. The ferroelectric nature of the BiFeO3–CoFe2O4 composite is confirmed by several scanning probe microscopy techniques. At room temperature, the composite exhibits a magnetoelectric voltage coefficient of α ME  =  17.5 V (cm · Oe)‑1, while a single-phase BiFeO3 thin film shows a α ME value of 4.2 V (cm · Oe)‑1. The high magnetoelectric voltage coefficient is interpreted to be the result of the interfacial interaction between the ferrimagnetic CoFe2O4 nanocrystallites and the multiferroic BiFeO3 matrix.

  9. Coexistance of magnetoelectric effect and exchange bias in Ni50.3Mn36.9Sb12.8/BiFeO3 heterostructure thin film

    Science.gov (United States)

    Barman, Rahul; Kaur, Davinder

    2016-05-01

    In the present study structural, magnetic and ferroelectric properties of Ni50.3Mn36.9Sb12.8/BiFeO3 heterostructure thin film, grown on LaNiO3 coated Si (100) substrate has been systematically investigated. Ni50.3Mn36.9Sb12.8 film exhibits L21 structure with preferred (220) orientation. The bottom LaNiO3 layer was implemented to favor the growth of pervoskite BiFeO3 film with (l00) orientation. The shift in hysteresis loop up to 34 Oe from the origin was observed at 300 K which is mainly due to the coupling of FM-AFM spins at the interface. Besides the exchange bias effect, large coupling between ferromagnetic and ferroelectric order parameters was also found with maximum coupling sensitivity of 7.58 V/cm-Oe at 300K in Ni50.3Mn36.9Sb12.8/BiFeO3 heterostructure thin film. The observed magneto-electric effect in this heterostructure is due to the transfer of strain from ferromagnetic shape memory alloy Ni50.3Mn36.9Sb12.8 layer to multiferroic BiFeO3 layer in the presence of magnetic field. Hence, coexistence of magneto-electric coupling and exchange bias in Ni50.3Mn36.9Sb12.8/BiFeO3 heterostructure make them a promising candidate for various multifunctional MEMS devices.

  10. Prediction of variation in d-orbital occupancy in strain induced tetragonal phase of BiFeO3 thin film

    Science.gov (United States)

    Verma, Manish; Ram, Kanik

    2016-05-01

    A theoretical study of the possible variation of d-orbital occupancy while going from the rhombohedral bulk phase to the strain induced tetragonal phase of BiFeO3 thin film has been carried out. A possible existence of an intermediate spin (IS) state, S=3/2 and a low spin (LS) state, S=1/2 in the tetragonal phase has been predicted, thereby clearly establishing the role of strain behind the d-orbital occupancy.

  11. Prediction of variation in d-orbital occupancy in strain induced tetragonal phase of BiFeO3 thin film

    Directory of Open Access Journals (Sweden)

    Manish Verma

    2016-05-01

    Full Text Available A theoretical study of the possible variation of d-orbital occupancy while going from the rhombohedral bulk phase to the strain induced tetragonal phase of BiFeO3 thin film has been carried out. A possible existence of an intermediate spin (IS state, S=3/2 and a low spin (LS state, S=1/2 in the tetragonal phase has been predicted, thereby clearly establishing the role of strain behind the d-orbital occupancy.

  12. Reduced Coercive Field in BiFeO3 Thin Films through Domain Engineering

    Energy Technology Data Exchange (ETDEWEB)

    Shelke, Vilas K [ORNL; Mazumdar, Dipanjan [ORNL; Srinivasan, Dr. Gopalan [Oakland University, Rochester, MI; Jesse, Stephen [ORNL; Kalinin, Sergei V [ORNL; Baddorf, Arthur P [ORNL; Gupta, Dr. Arunava [University of Alabama, Tuscaloosa

    2011-01-01

    The bismuth ferrite (BiFeO3) material offers a comprehensive package of multifunctionality. In addition to the multiferroic behavior, i.e. coexistence of electric and magnetic orderings,[1] it also exhibits photovoltaic effect, [2] metal-insulator transition,[3] electric modulation of conduction,[4] and terahertz radiation emission.[5] The possibility of joint control of electric, magnetic, and optical properties provides several degrees of freedom to design exotic devices. It is a green energy material in the sense that it is lead-free and energy-efficient due to cryogen-less functionality. Therefore, a wide variety of applications in terms of sensors, memories and spintronic devices are foreseen.[6] However, the incipient lower value of magneto-electric coupling has raised skepticism regarding its multiferroic capabilities and allied applications.[6] Nevertheless, the highest value of ferroelectric polarization (~ 100 C.cm-2) is very promising for next generation ferroelectric random access memory devices.

  13. Temperature dependences of ferroelectricity and resistive switching behavior of epitaxial BiFeO3 thin films

    Science.gov (United States)

    Lu, Zeng-Xing; Song, Xiao; Zhao, Li-Na; Li, Zhong-Wen; Lin, Yuan-Bin; Zeng, Min; Zhang, Zhang; Lu, Xu-Bing; Wu, Su-Juan; Gao, Xing-Sen; Yan, Zhi-Bo; Liu, Jun-Ming

    2015-10-01

    We investigate the resistive switching and ferroelectric polarization properties of high-quality epitaxial BiFeO3 thin films in various temperature ranges. The room temperature current-voltage (I-V) curve exhibits a well-established polarization-modulated memristor behavior. At low temperatures ( 253 K), the I-V behaviors are governed by both space-charge-limited conduction (SCLC) and Ohmic behavior. The polarization reversal is able to trigger the conduction switching from Ohmic to SCLC behavior, leading to the observed ferroelectric resistive switching. At a temperature of > 298 K, there occurs a new resistive switching hysteresis at high bias voltages, which may be related to defect-mediated effects. Project supported by the National Natural Science Foundation of China (Grant Nos. 51272078 and 51332007), the State Key Program for Basic Research of China (Grant No 2015CB921202), the Guangdong Provincial Universities and Colleges Pearl River Scholar Funded Scheme, China (2014), the International Science & Technology Cooperation Platform Program of Guangzhou, China (Grant No. 2014J4500016), and the Program for Changjiang Scholars and Innovative Research Team in University of China (Grant No. IRT1243).

  14. Synthesis of BiFeO3 thin films on single-terminated Nb : SrTiO3 (111 substrates by intermittent microwave assisted hydrothermal method

    Directory of Open Access Journals (Sweden)

    Ivan Velasco-Davalos

    2016-06-01

    Full Text Available We report on a simple and fast procedure to create arrays of atomically flat terraces on single crystal SrTiO3 (111 substrates and the deposition of ferroelectric BiFeO3 thin films on such single-terminated surfaces. A microwave-assisted hydrothermal method in deionized water and ammonia solution selectively removes either (SrO34− or Ti4+ layers to ensure the same chemical termination on all terraces. Measured step heights of 0.225 nm (d111 and uniform contrast in the phase image of the terraces confirm the single termination in pure and Nb doped SrTiO3 single crystal substrates. Multiferroic BiFeO3 thin films were then deposited by the same microwave assisted hydrothermal process on Nb : SrTiO3 (111 substrates. Bi(NO33 and Fe(NO33 along with KOH served as the precursors solution. Ferroelectric behavior of the BiFeO3 films on Nb : SrTiO3 (100 substrates was verified by piezoresponse force microscopy.

  15. Synthesis of BiFeO3 thin films on single-terminated Nb : SrTiO3 (111) substrates by intermittent microwave assisted hydrothermal method

    Science.gov (United States)

    Velasco-Davalos, Ivan; Ambriz-Vargas, Fabian; Kolhatkar, Gitanjali; Thomas, Reji; Ruediger, Andreas

    2016-06-01

    We report on a simple and fast procedure to create arrays of atomically flat terraces on single crystal SrTiO3 (111) substrates and the deposition of ferroelectric BiFeO3 thin films on such single-terminated surfaces. A microwave-assisted hydrothermal method in deionized water and ammonia solution selectively removes either (SrO3)4- or Ti4+ layers to ensure the same chemical termination on all terraces. Measured step heights of 0.225 nm (d111) and uniform contrast in the phase image of the terraces confirm the single termination in pure and Nb doped SrTiO3 single crystal substrates. Multiferroic BiFeO3 thin films were then deposited by the same microwave assisted hydrothermal process on Nb : SrTiO3 (111) substrates. Bi(NO3)3 and Fe(NO3)3 along with KOH served as the precursors solution. Ferroelectric behavior of the BiFeO3 films on Nb : SrTiO3 (100) substrates was verified by piezoresponse force microscopy.

  16. Chemistry of the Fe2O3/BiFeO3 Interface in BiFeO3 Thin Film Heterostructures

    Directory of Open Access Journals (Sweden)

    Valanoor Nagarajan

    2010-12-01

    Full Text Available We investigate the interfacial chemistry of secondary Fe2O3 phases formed in a BiFeO3 (BFO layer in BFO/ La0.67Sr0.33MnO3 (LSMO/SrTiO3 (STO heterostructures. A combination of high-resolution spherical aberration corrected scanning TEM and spectroscopy results, reveals that specific chemical and crystallographic similarities between Fe2O3 and BFO, enable the BFO layer to form a facile host for Fe2O3.

  17. Chemistry of the Fe2O3/BiFeO3 interface in BiFeO3 thin film heterostructures

    OpenAIRE

    Valanoor Nagarajan; Ramasse, Quentin M.; Miryam Arredondo; Kashinath Bogle

    2010-01-01

    We investigate the interfacial chemistry of secondary Fe2O3 phases formed in a BiFeO3 (BFO) layer in BFO/ La0.67Sr0.33MnO3 (LSMO)/SrTiO3 (STO) heterostructures. A combination of high-resolution spherical aberration corrected scanning TEM and spectroscopy results, reveals that specific chemical and crystallographic similarities between Fe2O3 and BFO, enable the BFO layer to form a facile host for Fe2O3.

  18. Correlation of High Magnetoelectric Coupling with Oxygen Vacancy Superstructure in Epitaxial Multiferroic BaTiO3-BiFeO3 Composite Thin Films

    Directory of Open Access Journals (Sweden)

    Michael Lorenz

    2016-01-01

    Full Text Available Epitaxial multiferroic BaTiO3-BiFeO3 composite thin films exhibit a correlation between the magnetoelectric (ME voltage coefficient αME and the oxygen partial pressure during growth. The ME coefficient αME reaches high values up to 43 V/(cm·Oe at 300 K and at 0.25 mbar oxygen growth pressure. The temperature dependence of αME of the composite films is opposite that of recently-reported BaTiO3-BiFeO3 superlattices, indicating that strain-mediated ME coupling alone cannot explain its origin. Probably, charge-mediated ME coupling may play a role in the composite films. Furthermore, the chemically-homogeneous composite films show an oxygen vacancy superstructure, which arises from vacancy ordering on the {111} planes of the pseudocubic BaTiO3-type structure. This work contributes to the understanding of magnetoelectric coupling as a complex and sensitive interplay of chemical, structural and geometrical issues of the BaTiO3-BiFeO3 composite system and, thus, paves the way to practical exploitation of magnetoelectric composites.

  19. Local Magnetoelectric Effect in La-Doped BiFeO3 Multiferroic Thin Films Revealed by Magnetic-Field-Assisted Scanning Probe Microscopy.

    Science.gov (United States)

    Pan, Dan-Feng; Zhou, Ming-Xiu; Lu, Zeng-Xing; Zhang, Hao; Liu, Jun-Ming; Wang, Guang-Hou; Wan, Jian-Guo

    2016-12-01

    Multiferroic La-doped BiFeO3 thin films have been prepared by a sol-gel plus spin-coating process, and the local magnetoelectric coupling effect has been investigated by the magnetic-field-assisted scanning probe microscopy connected with a ferroelectric analyzer. The local ferroelectric polarization response to external magnetic fields is observed and a so-called optimized magnetic field of ~40 Oe is obtained, at which the ferroelectric polarization reaches the maximum. Moreover, we carry out the magnetic-field-dependent surface conductivity measurements and illustrate the origin of local magnetoresistance in the La-doped BiFeO3 thin films, which is closely related to the local ferroelectric polarization response to external magnetic fields. This work not only provides a useful technique to characterize the local magnetoelectric coupling for a wide range of multiferroic materials but also is significant for deeply understanding the local multiferroic behaviors in the BiFeO3-based systems. PMID:27356565

  20. Controllability study on the preparation of pure phase BiFeO3 thin films by liquid phase self-assembled method

    International Nuclear Information System (INIS)

    Pure phase BiFeO3 (BFO) thin films were prepared on the ITO/glass substrates covered with functionalized OTS self-assembled monolayers (SAMs) by controllable liquid phase self-assembled method. The hydrophobic surface of OTS-SAMs was changed into hydrophilic surface after UV irradiation, which is helpful to make BFO precursor solutions fully wet the substrate surface. A dense film was formed only on the hydrophilic silnaol group regions, which shows the selectively deposition of BFO precursors. Changing the pH value of BFO precursor solutions will affect the phase purity. The pure phase BFO thin films can be obtained under various pH values, which indicates that the liquid phase self-assembled method is controllable. All pure phase BFO films are dense, smooth, well-grown polycrystalline films, but the size of grains increased gradually along with the increase of pH values. The micropattern of BiFeO3 film has clear edges. The possible growth mechanism of BFO thin films was discussed.

  1. Origin of the Enhanced Polarization in La and Mg Co-substituted BiFeO3 Thin Film during the Fatigue Process

    OpenAIRE

    Ke, Qingqing; Kumar, Amit; Lou, Xiaojie; Zeng, Kaiyang; Wang, John

    2012-01-01

    We have studied the polarization fatigue of La and Mg co-substituted BiFeO3 thin film, where a polarization peak is observed during the fatigue process. The origin of such anomalous behavior is analyzed on the basis of the defect evolution using temperature-dependent impedance spectroscopy. It shows that the motion of oxygen vacancies (VO..) is associated with a lower energy barrier, accompanied by the injection of electrons into the film during the fatigue process. A qualitative model is pro...

  2. Revealing the flexoelectricity in the mixed-phase regions of epitaxial BiFeO3 thin films.

    Science.gov (United States)

    Cheng, Cheng-En; Liu, Heng-Jui; Dinelli, Franco; Chen, Yi-Chun; Chang, Chen-Shiung; Chien, Forest Shih-Sen; Chu, Ying-Hao

    2015-01-01

    Understanding the elastic response on the nanoscale phase boundaries of multiferroics is an essential issue in order to explain their exotic behaviour. Mixed-phase BiFeO3 films, epitaxially grown on LaAlO3 (001) substrates, have been investigated by means of scanning probe microscopy to characterize the elastic and piezoelectric responses in the mixed-phase region of rhombohedral-like monoclinic (MI) and tilted tetragonal-like monoclinic (MII,tilt) phases. Ultrasonic force microscopy reveal that the regions with low/high stiffness values topologically coincide with the MI/MII,tilt phases. X-ray diffraction strain analysis confirms that the MI phase is more compliant than the MII,tilt one. Significantly, the correlation between elastic modulation and piezoresponse across the mixed-phase regions manifests that the flexoelectric effect results in the enhancement of the piezoresponse at the phase boundaries and in the MI regions. This accounts for the giant electromechanical effect in strained mixed-phase BiFeO3 films. PMID:25627445

  3. Effects of annealing atmosphere on crystallization and electrical properties in BiFeO3 thin films by chemical solution deposition(CSD)

    International Nuclear Information System (INIS)

    BiFeO3 (BFO) thin films have been prepared on platinized silicon substrates by chemical solution deposition (CSD) and annealed at 600 .deg. C for 1 hour under various atmospheres, i.e., O2, Air and N2. Effects of annealing atmospheres on the crystallization and electrical properties of BFO films were investigated. Crystallization behavior and electrical properties of BFO films depend on the oxygen partial pressure of the annealing atmosphere. The BFO thin film annealed in N2 atmosphere showed a good crystallinity. The surface roughness of the BFO film decreased with lowering oxygen partial pressure of the annealing atmosphere. Low leakage current density and P-E hysteresis were found only in the BFO film annealed at 600 .deg. C under N2 atmosphere. Leakage current density, polarization (at zero electric field) and electric field (at zero polarization) of the BFO film annealed at 600 .deg. C under N2 are 5 x 10-7 A/cm2 at 1 V, 0.2 μC/cm2 and 15kV/cm, respectively

  4. Cooperative effect of oxygen-vacancy-rich layer and ferroelectric polarization on photovoltaic properties in BiFeO3 thin film capacitors

    Science.gov (United States)

    Matsuo, Hiroki; Kitanaka, Yuuki; Inoue, Ryotaro; Noguchi, Yuji; Miyayama, Masaru

    2016-01-01

    Photovoltaic (PV) properties of ferroelectric SrRuO3/BiFeO3/SrRuO3 (SRO/BFO/SRO) epitaxial thin-film capacitors are investigated. The experimental results of the markedly reduced PV response caused by the doping of Mn provide evidence that the PV properties originate not from the bulk-derived PV effect but from an interfacial band bending. We show that the capacitors having a defective layer composed of oxygen vacancies at the SRO/BFO interface exhibit a markedly large photocurrent. Our study demonstrates that a cooperative effect between the interface charges arising from ferroelectric polarization and the oxygen-vacancy-rich layer enhances the PV response in capacitor form in the BFO system.

  5. Photo-magnetic assisted ferroelectric polarization in magneto-electric BiFeO3/BaTiO3 thin film

    International Nuclear Information System (INIS)

    We examined the effect of light illumination on the magneto-electric behavior of the BiFeO3 thin film which deposited onto BaTiO3 piezoelectric layer by the aid of pulsed laser deposition technique. The ferroelectric polarization of the sample has been measured under electric field bias and illumination of different power of laser diode with a center wavelength of 406 nm in the presence of magnetic field. The photo-magnetic assisted ferroelectric polarization of the sample has been observed when the sample illuminated with light under magnetic field. Our results show the linear dependence of this answer with the power of light. This effect can possibly open a research development in photoassisted ferroelectric behavior properties for next generation devices

  6. Resistive switching properties of Ce and Mn co-doped BiFeO3 thin films for nonvolatile memory application

    Directory of Open Access Journals (Sweden)

    Zhenhua Tang

    2013-12-01

    Full Text Available The Ce and Mn co-doped BiFeO3 (BCFMO thin films were synthesized on Pt/Ti/SiO2/Si substrates using a sol-gel method. The unipolar resistive switching (URS and bipolar resistive switching (BRS behaviors were observed in the Pt/BCFMO/Pt device structure, which was attributed to the formation/rupture of metal filaments. The fabricated device exhibits a large ROFF/RON ratio (>80, long retention time (>105 s and low programming voltages (<1.5 V. Analysis of linear fitting current-voltage curves suggests that the space charge limited leakage current (SCLC and Schottky emission were observed as the conduction mechanisms of the devices.

  7. Thickness-dependent phase boundary in Sm-doped BiFeO3 piezoelectric thin films on Pt/Ti/SiO2/Si substrates.

    Science.gov (United States)

    Sun, Wei; Li, Jing-Feng; Zhu, Fangyuan; Yu, Qi; Cheng, Li-Qian; Zhou, Zhen

    2015-08-14

    Sm-doped BiFeO3 thin films were fabricated on platinized silicon substrates via a sol-gel method. Sm contents and thicknesses were varied in a wide range to investigate their effects on the phase structure and piezoelectricity. X-ray diffraction and Raman spectroscopy experiments revealed a rhombohedral to orthorhombic phase transition and the co-existence of both phases in a certain compositional vicinity. It is found that the proportion of a rhombohedral phase increased with film thickness at the compositions corresponding to the phase transition boundary, indicating the influence of the film thickness on the phase structure. The phase transition phenomenon and film thickness effect on the boundary were also studied by piezoresponse force microscopy. Based on the structure analysis and piezoelectric characterization results, a phase diagram of thickness versus composition was proposed, in which the morphotropic phase boundary was located at 9% to 11% in thinner Sm-doped films and shifted towards the Sm-rich side with increasing thickness. PMID:26113368

  8. Nanoscale study of perovskite BiFeO3/spinel (Fe,Zn)3O4 co-deposited thin film by electrical scanning probe methods

    International Nuclear Information System (INIS)

    Highlights: • A BFO/FZO sample has been prepared using PLD and investigated by SPM techniques. • SPM/HAADF-STEM images have allowed to understand the sample physical properties. • Without destructive material methods we were able to distinguish BFO and FZO. - Abstract: For this study, a BiFeO3 (BFO) perovskite/(Fe,Zn)3O4 (FZO) spinel sample grown on SrTiO3:Nb (0 0 1) has been prepared using pulsed laser deposition with a single target composition of (Bi1.1FeO3)0.65(Fe2.2Zn0.8O4)0.35. The nanoscale electrical properties of ferroelectric BFO/semi-conducting FZO thin film have been investigated using piezoresponse force microscopy (PFM) and conductive-atomic force microscopy (C-AFM). Scanning probe methods reveal that BFO grows as nano-islets with a complex structure which is coherent with the cross-sectional high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images. The comparison between nanoscale electrical techniques and HAADF-STEM images have allowed to understand the origin of the different physical properties of the multiferroic/magnetoconductive co-deposited thin film at the nanoscale. By using PFM/C-AFM techniques, we were able to fully distinguish BFO and FZO materials in the nanostructured sample without using destructive material characterization methods

  9. Hydrothermal epitaxial multiferroic BiFeO3 thick film by addition of the PVA

    International Nuclear Information System (INIS)

    Graphical abstract: Epitaxial BiFeO3 (BFO) thin films were fabricated on (0 0 1)-oriented single-crystal SrRuO3(SRO)/SrTiO3(STO) structures by PVA-assistant hydrothermal method. The electrical properties observed in BFO (0 0 1) thin films are superior to those of hydrothermal epitaxy reported previously, which indicates PVA plays an important role in fabricating BFO films by using hydrothermal method. Highlights: •We grow BiFeO3 thick film by hydrothermal method. •PVA as assistant agent epitaxially grow BiFeO3 thick film. •The ferroelectric properties of BiFeO3 thick film were measured. •The electrical properties observed in BFO (0 0 1) thin films are superior to those of hydrothermal epitaxy reported previously. -- Abstract: Hydrothermal method is a much simpler method of epitaxial multiferroic BiFeO3 (BFO) film than physical/chemical vapor deposition methods. In this work, epitaxial BFO thin films were fabricated on (0 0 1)-oriented single-crystal SrRuO3(SRO)/SrTiO3(STO) structures by PVA-assistant hydrothermal method. The results of θ–2θ scan, ω scan and reciprocal space mappings (RSMs) measured by synchrotron high resolution X-ray diffraction and high-resolution transmission electron microscopy (HRTEM) suggest that the BFO films have relaxed to a single-phase monoclinic structure. The electrical properties observed in BFO (0 0 1) thin films are superior to those of hydrothermal epitaxy reported previously, which indicates PVA plays an important role in fabricating BFO films by using hydrothermal method

  10. Sputter-prepared (001) BiFeO3 thin films with ferromagnetic L10-FePt(001) electrode on glass substrates

    OpenAIRE

    Chang, Huang-Wei; Yuan, Fu-Te; Shih, Chih-Wei; Ku, Ching-Shun; Chen, Ping-Han; Wang, Chang-Ren; Chang, Wen-Cheng; Jen, Shien-Uang; Lee, Hsin-yi

    2012-01-01

    Highly textured BiFeO3(001) films were formed on L10-FePt(001) bottom electrodes on glass substrates by sputtering at reduced temperature of 400°C. Good electric polarization 2P r = 80 and 95 μC/cm2, comparable to that of the reported epitaxial films, and coercivity E c = 415 and 435 kV/cm are achieved in the samples with 20-nm- and 30-nm-thick electrodes. The BiFeO3(001) films show different degrees of compressive strain. The relation between the variations of strain and 2P r suggests that t...

  11. Photo-carrier control of exchange bias in BiFeO3/La2/3Sr1/3MnO3 thin films

    International Nuclear Information System (INIS)

    We report the facile control of exchange bias in BiFeO3/La2/3Sr1/3MnO3 (BFO/LSMO) thin films on an SrTiO3 (STO) substrate using light irradiation. Illumination with weak red light (λ: 630 nm, intensity: ∼1 mW/cm2) reduced the exchange bias field (HE) of BFO/LSMO from +30 Oe in the dark to −2 Oe with red light. In accompanying the decrease of HE, the resistance of BFO/LSMO significantly increased. These results were attributed to the reduction in the hole-doping ratio of LSMO and the weakened exchange coupling between Fe and Mn spins at the interface, resulting from photo-injected electrons from the STO substrate. Successive turning on/off of red light gives rise to cyclical change of corresponding HE, which should be useful for applications like photo-controlled tunneling magnetoresistance devices.

  12. Intriguing photo-control of exchange bias in BiFeO3/La2/3Sr1/3MnO3 thin films on SrTiO3 substrates.

    Science.gov (United States)

    Sung, Kil Dong; Lee, Tae Kwon; Jung, Jong Hoon

    2015-01-01

    To date, electric fields have been widely used to control the magnetic properties of BiFeO3-based antiferromagnet/ferromagnet heterostructures through application of an exchange bias. To extend the applicability of exchange bias, however, an alternative mechanism to electric fields is required. Here, we report the photo-control of exchange bias in BiFeO3/La2/3Sr1/3MnO3 thin films on an SrTiO3 substrate. Through an ex situ pulsed laser deposition technique, we successfully synthesized epitaxial BiFeO3/La2/3Sr1/3MnO3 thin films on SrTiO3 substrates. By measuring magnetoresistance under light illumination, we investigated the effect of light illumination on resistance, exchange bias, and coercive field in BiFeO3/La2/3Sr1/3MnO3 thin films. After illumination of red and blue lights, the exchange bias was sharply reduced compared to that measured in the dark. With increasing light intensity, the exchange bias under red and blue lights initially decreased to zero and then appeared again. It is possible to reasonably explain these behaviors by considering photo-injection from SrTiO3 and the photo-conductivity of La2/3Sr1/3MnO3. This study may provide a fundamental understanding of the mechanism underlying photo-controlled exchange bias, which is significant for the development of new functional spintronic devices. PMID:25852417

  13. Electrical conduction mechanism in BiFeO3-based ferroelectric thin-film capacitors: Impact of Mn doping

    Directory of Open Access Journals (Sweden)

    Hiroki Matsuo

    2015-12-01

    Full Text Available Electrical conduction properties of SrRuO3(SRO/BiFeO3(BFO/SRO and SRO/10% Mn-doped BFO(BFMO/SRO ferroelectric thin-film capacitors are investigated. The BFO capacitors exhibit a switchable diode effect accompanied by a conduction change from ohmic to space-charge-limited current with increasing external field. In contrast, the BFMO capacitors show only an ohmic conduction, arising from a considerable reduction in depletion layer width at the SRO/BFMO interfaces. These results suggest that the diode property can be tuned by Mn content in the BFO film. Our study opens the possibility of controlling the diode effect in BFO-based devices by a dilute Mn doping.

  14. Photovoltaic effect and enhanced magnetization in 0.9(BiFeO3)–0.1(YCrO3) composite thin film fabricated using sequential pulsed laser deposition

    International Nuclear Information System (INIS)

    We report on the photovoltaic effect and multiferroic properties of a 0.9(BiFeO3)–0.1(YCrO3) composite thin film deposited on a Pt/TiO2/SiO2/Si substrate by sequential ablation of BiFeO3 and YCrO3 ceramic targets using pulsed laser deposition. The desired composition of the composite was achieved by controlling the ablation time of respective targets. As confirmed by the x-ray diffraction pattern the resultant film was found to be polycrystalline in nature and composed of a mixture of both rhombohedral BiFeO3 and orthorhombic YCrO3 phases. Interesting multiferroic properties in terms of an enhanced saturation magnetization of ∼14 emu cm−3 and the remnant polarization of ∼4.5 µC cm−2 were observed where the enhancement in magnetization as compared to pristine BiFeO3 could be attributed to the super-exchange interaction between Fe and Cr-ions. The photovoltaic properties of the composite thin film were studied under white light illumination in both top–bottom and lateral electrode configurations. Short circuit current densities (JSC) = 1.48 µA cm−2 and 0.44 µA cm−2, and open circuit voltages (VOC) = 0.51 V and 0.32 V were observed in top–bottom and lateral electrode configurations, respectively. (paper)

  15. Imaging of coherent magneto-elastic domains in multiferroic BiFeO3 films

    OpenAIRE

    Price, N. Waterfield; Johnson, R. D.; Saenrang, W.; Maccherozzi, F; Dhesi, S.S.; Bombardi, A.; Chmiel, F. P.; Eom, C. -B.; Radaelli, P. G.

    2015-01-01

    A current challenge presented in thin film physics is imaging and controlling antiferromagnetic domains at the nanoscale. By employing a combination of non-resonant x-ray magnetic scattering, neutron diffraction and vector-mapped x-ray magnetic linear dichroism photoemission electron microscopy, we have directly visualised the sub-micron scale antiferromagnetic domain structure of epitaxial (111) BiFeO3 films. We find that these domains are coherently coupled to crystallographic domain struct...

  16. Thickness-dependent polarization of strained BiFeO3 films with constant tetragonality

    OpenAIRE

    Rault, J. E.; W Ren; Prosandeev, S.; Lisenkov, S.; Sando, D.; S. Fusil; Bibes, M.; Barthelemy, A.; Bellaiche, L.; Barrett, N.

    2012-01-01

    We measure the remnant polarization of ferroelectric domains in BiFeO3 films down to 3.6 nm using low energy electron and photoelectron emission microscopy. The measured polarization decays strongly below a critical thickness of 5-7 nm predicted by continuous medium theory whereas the tetragonal distortion does not change. We resolve this apparent contradiction using first-principles-based effective Hamiltonian calculations. In ultra thin films the energetics of near open circuit electrical b...

  17. Electrical and piezoelectric properties of BiFeO3 thin films grown on SrxCa1−xRuO3-buffered SrTiO3 substrates

    KAUST Repository

    Yao, Yingbang

    2012-06-01

    (001)-oriented BiFeO 3 (BFO) thin films were grown on Sr xCa 1-xRuO 3- (SCRO; x = 1, 0.67, 0.33, 0) buffered SrTiO 3 (001) substrates using pulsed laser deposition. The microstructural, electrical, ferroelectric, and piezoelectric properties of the thin films were considerably affected by the buffer layers. The interface between the BFO films and the SCRO-buffer layer was found to play a dominant role in determining the electrical and piezoelectric behaviors of the films. We found that films grown on SrRuO 3-buffer layers exhibited minimal electrical leakage while films grown on Sr 0.33Ca 0.67RuO 3-buffer layers had the largest piezoelectric response. The origin of this difference is discussed. © 2012 American Institute of Physics.

  18. Large piezoelectric response of BiFeO3/BaTiO3 polycrystalline films induced by the low-symmetry phase.

    Science.gov (United States)

    Hou, Y F; Li, W L; Zhang, T D; Wang, W; Cao, W P; Liu, X L; Fei, W D

    2015-05-01

    BaTiO3, BiFeO3 and BiFeO3/BaTiO3 polycrystalline films were prepared by the radio frequency magnetron sputtering on the Pt/Ti/SiO2/Si substrate. The phase structure, converse piezoelectric coefficient and domain structure of BaTiO3, BiFeO3 and BiFeO3/BaTiO3 thin films are characterized by XRD and PFM, respectively. The converse piezoelectric coefficient d33 of BiFeO3/BaTiO3 thin films is 119.5 pm V(-1), which is comparable to that of lead-based piezoelectric films. The large piezoelectric response of BiFeO3/BaTiO3 thin films is ascribed to the low-symmetry T-like phase BiFeO3, because the spontaneous polarization vector of T-like phase (with monoclinic symmetry) BiFeO3 can rotate easily under external field. In addition, the reduced leakage current and major domains with upward polarization are also attributed to the large piezoelectricity. PMID:25866266

  19. Magnetic Phase Formation in Self-Assembled Epitaxial BiFeO3-MgO and BiFeO3-MgAl2O4 Nanocomposite Films Grown by Combinatorial Pulsed Laser Deposition.

    Science.gov (United States)

    Kim, Dong Hun; Sun, XueYin; Kim, Tae Cheol; Eun, Yun Jae; Lee, Taeho; Jeong, Sung Gyun; Ross, Caroline A

    2016-02-01

    Self-assembled epitaxial BiFeO3-MgO and BiFeO3-MgAl2O4 nanocomposite thin films were grown on SrTiO3 substrates by pulsed laser deposition. A two-phase columnar structure was observed for BiFeO3-MgO codeposition within a small window of growth parameters, in which the pillars consisted of a magnetic spinel phase (Mg,Fe)3O4 within a BiFeO3 matrix, similar to the growth of BiFeO3-MgFe2O4 nanocomposites reported elsewhere. Further, growth of a nanocomposite with BiFeO3-(CoFe2O4/MgO/MgFe2O4), in which the minority phase was grown from three different targets, gave spinel pillars with a uniform (Mg,Fe,Co)3O4 composition due to interdiffusion during growth, with a bifurcated shape from the merger of neighboring pillars. BiFeO3-MgAl2O4 did not form a well-defined vertical nanocomposite in spite of having lower lattice mismatch, but instead formed a two-phase film with in which the spinel phase contained Fe. These results illustrate the redistribution of Fe between the oxide phases during oxide codeposition to form a ferrimagnetic phase from antiferromagnetic or nonmagnetic targets. PMID:26750565

  20. Suppression of creep-regime dynamics in epitaxial ferroelectric BiFeO3 films.

    Science.gov (United States)

    Shin, Y J; Jeon, B C; Yang, S M; Hwang, I; Cho, M R; Sando, D; Lee, S R; Yoon, J-G; Noh, T W

    2015-01-01

    Switching dynamics of ferroelectric materials are governed by the response of domain walls to applied electric field. In epitaxial ferroelectric films, thermally-activated 'creep' motion plays a significant role in domain wall dynamics, and accordingly, detailed understanding of the system's switching properties requires that this creep motion be taken into account. Despite this importance, few studies have investigated creep motion in ferroelectric films under ac-driven force. Here, we explore ac hysteretic dynamics in epitaxial BiFeO3 thin films, through ferroelectric hysteresis measurements, and stroboscopic piezoresponse force microscopy. We reveal that identically-fabricated BiFeO3 films on SrRuO3 or La0.67Sr0.33MnO3 bottom electrodes exhibit markedly different switching behaviour, with BiFeO3/SrRuO3 presenting essentially creep-free dynamics. This unprecedented result arises from the distinctive spatial inhomogeneities of the internal fields, these being influenced by the bottom electrode's surface morphology. Our findings further highlight the importance of controlling interface and defect characteristics, to engineer ferroelectric devices with optimised performance. PMID:26014521

  1. Optical, ferroelectric and magnetic properties of multiferroelectric BiFeO3-(K0.5Na0.5)0.4(Sr 0.6Ba0.4)0.8Nb2O6 thin films

    KAUST Repository

    Yao, Yingbang

    2014-02-01

    Multiferroic BiFeO3-(K0.5Na0.5) 0.4(Sr0.6Ba0.4)0.8Nb 2O6 (BFO-KNSBN) trilayer thin films, were epitaxially grown on MgO(0 0 1) and SrTiO3(0 0 1) by using pulsed laser deposition (PLD). Their ferroelectric, magnetic, dielectric and optical properties were investigated. It was found that both ferroelectric polarization and dielectric constant of the films were enhanced by introducing KNSBN as a barrier layer. Meanwhile, ferromagnetism of BFO was maintained. More interestingly, a double hysteresis magnetic loop was observed in the KNSBN-BFO-KNSBN trilayer films, where exchange bias and secondary phase in the BFO layer played crucial roles. Interactions between adjacent layers were revealed by temperature-dependent Raman spectroscopic measurements. © 2013 Elsevier B.V. All rights reserved.

  2. Tuning the atomic and domain structure of epitaxial films of multiferroic BiFeO3

    OpenAIRE

    Daumont, C. J. M.; Farokhipoor, S.; Ferri, A; Wojdel, J. C.; Iniguez, Jorge; Kooi, B. J.; Noheda, Beatriz; Wojdeł, J.C.

    2010-01-01

    Recent works have shown that the domain walls of room-temperature multiferroic BiFeO3 (BFO) thin films can display distinct and promising functionalities. It is thus important to understand the mechanisms underlying domain formation in these films. High-resolution x-ray diffraction and piezoforce microscopy, combined with first-principles simulations, have allowed us to characterize both the atomic and domain structure of BFO films grown under compressive strain on (001)-SrTiO3, as a function...

  3. Joining Chemical Pressure and Epitaxial Strain to Yield Y-doped BiFeO3 Thin Films with High Dielectric Response.

    Science.gov (United States)

    Scarisoreanu, N D; Craciun, F; Birjega, R; Ion, V; Teodorescu, V S; Ghica, C; Negrea, R; Dinescu, M

    2016-01-01

    BiFeO3 is one of the most promising multiferroic materials but undergoes two major drawbacks: low dielectric susceptibility and high dielectric loss. Here we report high in-plane dielectric permittivity (ε' ∼2500) and low dielectric loss (tan δ < 0.01) obtained on Bi0.95Y0.05FeO3 films epitaxially grown on SrTiO3 (001) by pulsed laser deposition. High resolution transmission electron microscopy and geometric phase analysis evidenced nanostripe domains with alternating compressive/tensile strain and slight lattice rotations. Nanoscale mixed phase/domain ensembles are commonly found in different complex materials with giant dielectric/electromechanical (ferroelectric/ relaxors) or magnetoresistance (manganites) response. Our work brings insight into the joined role of chemical pressure and epitaxial strain on the appearance of nanoscale stripe structure which creates conditions for easy reorientation and high dielectric response, and could be of more general relevance for the field of materials science where engineered materials with huge response to external stimuli are a highly priced target. PMID:27157090

  4. Direct Observation of Magnetic Field Induced Ferroelectric Domain Evolution in Self-Assembled Quasi (0-3) BiFeO3-CoFe2O4 Thin Films.

    Science.gov (United States)

    Li, Linglong; Lu, Lu; Zhang, Dawei; Su, Ran; Yang, Guang; Zhai, Junyi; Yang, Yaodong

    2016-01-13

    Strain-mediated magnetoelectric (ME) coupling effect is expected in self-assembly heterostructures engineered by ferroelectric and ferromagnetic materials, contributing to the enhanced overall magnetoelectric effect. Microstructures as well as the connectivity configuration are considered to play a significant role in achieving efficient magnetoelectric properties. Different from the conventional (1-3) and (2-2) type composite films, we fabricate BiFeO3-CoFe2O4 (BFO-CFO) composite thin films with a novel quasi (0-3) type connectivity via a dual-target pulsed laser deposition process. The self-assembly growth mechanism has been studied, which demonstrates that the perovskite (BFO) matrix segments the connectivity of spinel (CFO) resulting in a quasi (0-3) composite. Direct observation of ferroelectric domain wall motion under external magnetic fields proves a strong magnetoelectric coupling effect in these (0-3) thin films. Our preliminary findings reveal the promising application potential of this new structure as multiferroic domain wall devices. PMID:26698906

  5. Reduced leakage in epitaxial BiFeO3 films following oxygen radio frequency plasma treatment

    International Nuclear Information System (INIS)

    Epitaxial BiFeO3 (BFO) films were deposited using pulsed laser deposition method. The prepared films were characterized using x-ray diffraction, x-ray reflectivity, ferroelectric loop tracer, and leakage current measurements before and after oxygen plasma treatment. The leakage current of the films, a crucial parameter in device applications, is observed to be reduced by two orders of magnitude with oxygen plasma treatment at room temperature. P-E hysteresis loops were observed in oxygen plasma treated BFO films. The observed results indicate the usefulness of oxygen radio frequency plasma treatment (RF 13.56 MHz), which is an effective and low temperature processing technique, in such lossy ferroelectric thin films.

  6. Untilting BiFeO3: The influence of substrate boundary conditions in ultra-thin BiFeO3 on SrTiO3

    Directory of Open Access Journals (Sweden)

    Yongsoo Yang

    2013-11-01

    Full Text Available We report on the role of oxygen octahedral tilting in the monoclinic-to-tetragonal phase transition in ultra-thin BiFeO3 films grown on (001 SrTiO3 substrates. Reciprocal space maps clearly show the disappearance of the integer-order Bragg peak splitting associated with the monoclinic phase when the film thickness decreases below 20 unit cells. This monoclinic-to-tetragonal transition is accompanied by the evolution of the half-order diffraction peaks, which reflects untilting of the oxygen octahedra around the [110] axis, proving that the octahedral tilting is closely correlated with the transition. This structural change is thickness-dependent, and different from a strain-induced transition in the conventional sense.

  7. Oxygen-vacancy-mediated Negative Differential Resistance in La and Mg co-substituted BiFeO3 Thin Film

    OpenAIRE

    Ke, Qingqing; Kumar, Amit; Lou, Xiaojie; Zeng, Kaiyang; Wang, John

    2012-01-01

    The conductive characteristics of Bi0.9La0.1Fe0.96Mg0.04O3(BLFM) thin film are investigated at various temperatures and a negative differential resistance (NDR) is observed in the thin film, where a leakage current peak occurs upon application of a downward electric field above 80 oC. The origin of the NDR behavior is shown to be related to the ionic defect of oxygen vacancies (VO..) present in the film. On the basis of analyzing the leakage mechanism and surface potential behavior, the NDR b...

  8. The enhanced photocurrent of epitaxial BiFeO3 film at 130 °C

    Science.gov (United States)

    Yang, Yuxi; Xu, Wenting; Xu, Xijun; Wang, Yaojin; Yuan, Guoliang; Wang, Yiping; Liu, Zhiguo

    2016-01-01

    The short-circuit photocurrent (ISC) that can be reversed by polarization switch enhances with temperature increasing to 130 °C in the epitaxial BiFeO3 thin film on SrTiO3 substrate. The La2/3Sr1/3MnO3/BiFeO3/indium tin oxide (In2O3:SnO2 = 9:1) junction shows the current rectifying characteristic and the photovoltaic effect at 20-130 °C. Importantly, the ISC can be reversed by the polarization switch in this temperature range. More charge carriers are activated and the density of free electrons enhances with the increase in the temperature, which results in the decrease in the depletion layer width. As a result, the open-circuit voltage decreases 50% and the ISC increases from 180 nA to 404 nA with the increase in the temperature from 20 °C to 130 °C. This suggests that the corresponding sensors and devices can be used at a relatively high temperature.

  9. BiFeO3 thin films: Novel effects

    Indian Academy of Sciences (India)

    V R Palkar; R Pinto

    2002-05-01

    In this paper we report synthesis of phase-pure highly resistive magnetoelectric BiFeO3 thin films on Pt/TiO2/SiO2/Si substrate by using pulsed laser deposition technique. For the first time saturated ferroelectric hysteresis loop has been observed. It has confirmed the presence of ferroelectricity in BiFeO3 compound. The films exhibit dielectric anomaly near Neel temperature. This anomaly is related to the influence of vanishing magnetic order on the electric order. In situ domain alignment occurs during observation of the films under transmission electron microscope.

  10. Variation of electric properties across the grain boundaries in BiFeO3 film

    Science.gov (United States)

    Stojadinović, Bojan; Vasić, Borislav; Stepanenko, Dimitrije; Tadić, Nenad; Gajić, Radoš; Dohčević-Mitrović, Zorana

    2016-02-01

    Stark differences in charge transport properties between the interior and the boundary regions of grains in an undoped BiFeO3 thin film have been found. The material is ferroelectric and each grain is a single domain. A spatial resolution that distinguishes between the grain interior and the boundary between the grains has been achieved by using piezoelectric force microscopy and conductive atomic force microscopy measurements. The local electric properties, as well as the local band gap show hysteresis only when probed in the grain interior, but do not show hysteresis when probed in the region around the boundary between two grains. The leakage current is more pronounced at the grain boundaries, and the region that carries significant current increases with the applied voltage.

  11. Electric and Magnetic Properties of Sputter Deposited BiFeO3 Films

    Directory of Open Access Journals (Sweden)

    N. Siadou

    2013-01-01

    Full Text Available Polycrystalline BiFeO3 films have been magnetron sputter deposited at room temperature and subsequently heat-treated ex situ at temperatures between 400 and 700°C. The deposition was done in pure Ar atmosphere, as the use of oxygen-argon mixture was found to lead to nonstoichiometric films due to resputtering effects. At a target-to-substrate distance d=2′′ the BiFeO3 structure can be obtained in larger range process gas pressures (2–7 mTorr but the films do not show a specific texture. At d=6′′ codeposition from BiFeO3 and Bi2O3 has been used. Films sputtered at low rate tend to grow with the (001 texture of the pseudo-cubic BiFeO3 structure. As the film structure does not depend on epitaxy similar results are obtained on different substrates. A result of the volatility of Bi, Bi rich oxide phases occur after heat treatment at high temperatures. A Bi2SiO5 impurity phase forms on the substrate side, and does not affect the properties of the main phase. Despite the deposition on amorphous silicon oxide substrate weak ferromagnetism phenomena and displaced loops have been observed at low temperatures showing that their origin is not strain. Ba, La, Ca, and Sr doping suppress the formation of impurity phases and leakage currents.

  12. Polarized Raman study on the lattice structure of BiFeO3 films prepared by pulsed laser deposition

    KAUST Repository

    Yang, Yang

    2014-11-01

    Polarized Raman spectroscopy was used to study the lattice structure of BiFeO3 films on different substrates prepared by pulsed laser deposition. Interestingly, the Raman spectra of BiFeO3 films exhibit distinct polarization dependences. The symmetries of the fundamental Raman modes in 50-700 cm-1 were identified based on group theory. The symmetries of the high order Raman modes in 900-1500 cm-1 of BiFeO3 are determined for the first time, which can provide strong clarifications to the symmetry of the fundamental peaks in 400-700 cm-1 in return. Moreover, the lattice structures of BiFeO3 films are identified consequently on the basis of Raman spectroscopy. BiFeO3 films on SrRuO3 coated SrTiO3 (0 0 1) substrate, CaRuO3 coated SrTiO3 (0 0 1) substrate and tin-doped indium oxide substrate are found to be in the rhombohedral structure, while BiFeO3 film on SrRuO3 coated Nb: SrTiO3 (0 0 1) substrate is in the monoclinic structure. Our results suggest that polarized Raman spectroscopy would be a feasible tool to study the lattice structure of BiFeO3 films.

  13. Influence of rare-earth elements doping on structure and optical properties of BiFeO3 thin films fabricated by pulsed laser deposition

    International Nuclear Information System (INIS)

    The Bi1−xEuxFeO3 (BEFOx, x = 0, 0.03, 0.05, 0.07, 0.1) films were grown on LaNiO3 coating Si substrates by pulsed laser deposition. X-ray diffraction patterns indicate that the films exhibit a (1 0 0)-highly oriented pseudocubic perovskite crystal structure. Scanning electron microscopy exhibits that the number of island-like structures decreases with increasing Eu dopant. The position of the A1-1 mode of the films in the Raman spectra shifts to higher wavenumber with increasing x. With increasing the amount of Eu, the refractive index increases and the extinction coefficient decreases. In addition, the band gap of BEFOx films decreases with increasing Eu dopant.

  14. Preferential Crystal Growth of (100)-Oriented BiFeO3 Films on Si Substrate

    Science.gov (United States)

    Hayashi, M.; Yasui, S.; Funakubo, H.; Uchida, H.

    2011-10-01

    Bi-based perovskite-type oxide materials such as BiFeO3 (BFO) and the related compounds receive much attention and have been developed actively as important candidates for Pb-free ferroelectric / piezoelectric materials instead of toxic Pb-based perovskite oxide materials. Recently, many researches have been reported for thin films of BFO by various film-deposition techniques for actual application of semiconductive devices, microactuators, etc. In this report, we tried preferential crystal growth of BFO films on semiconductive silicon substrates using uniaxial-(100)-oriented LaNiO3 (LNO) buffer layer. BFO films were fabricated via chemical solution deposition (CSD) technique on platinized silicon wafer [(111)Pt/TiO2/(100)Si] and (100)LNO-coated platinized silicon [(100)LNO/(111)Pt/TiO2/(100)Si] substrates. XRD analysis indicated that the films fabricated on (111)Pt/TiO2/(100)Si substrate consisted of randomly-oriented BFO crystal with lower crystallinity and trace amount of the second Bi2Fe4O9 phase. On the other hand, the films on (100)LNO/(111)Pt/TiO2/(100)Si consisted of uniaxial-(100)-oriented BFO crystal with higher crystallinity. The crystallization temperature these films were 450 and 400°C, respectively. These results suggest that the BFO crystal was grown epitaxially on uniaxial oriented (100)LNO plane which also had perovskite-type crystal structure. Consequently, (100)-oriented BFO films were prepared on Si substrate successfully using (100)LNO buffer layer.

  15. Preferential Crystal Growth of (100)-Oriented BiFeO3 Films on Si Substrate

    International Nuclear Information System (INIS)

    Bi-based perovskite-type oxide materials such as BiFeO3 (BFO) and the related compounds receive much attention and have been developed actively as important candidates for Pb-free ferroelectric / piezoelectric materials instead of toxic Pb-based perovskite oxide materials. Recently, many researches have been reported for thin films of BFO by various film-deposition techniques for actual application of semiconductive devices, microactuators, etc. In this report, we tried preferential crystal growth of BFO films on semiconductive silicon substrates using uniaxial-(100)-oriented LaNiO3 (LNO) buffer layer. BFO films were fabricated via chemical solution deposition (CSD) technique on platinized silicon wafer [(111)Pt/TiO2/(100)Si] and (100)LNO-coated platinized silicon [(100)LNO/(111)Pt/TiO2/(100)Si] substrates. XRD analysis indicated that the films fabricated on (111)Pt/TiO2/(100)Si substrate consisted of randomly-oriented BFO crystal with lower crystallinity and trace amount of the second Bi2Fe4O9 phase. On the other hand, the films on (100)LNO/(111)Pt/TiO2/(100)Si consisted of uniaxial-(100)-oriented BFO crystal with higher crystallinity. The crystallization temperature these films were 450 and 400deg. C, respectively. These results suggest that the BFO crystal was grown epitaxially on uniaxial oriented (100)LNO plane which also had perovskite-type crystal structure. Consequently, (100)-oriented BFO films were prepared on Si substrate successfully using (100)LNO buffer layer.

  16. Magnetoelectric coupling of spray pyrolysis deposited multiferroic BiFeO3 films

    International Nuclear Information System (INIS)

    Magnetoelectric effect has been studied in films of BiFeO3 with particle sizes in the range, 12 to 92 nm deposited by spray pyrolysis method. The field emission scanning electron microscopy images show that the films were uniform, dense and of near spherically shaped nano-particles. The ferroelectric loops were studied in the presence of magnetic field and about 30% increase in the remanent polarization was obtained. The enhanced polarization was observed above some critical value of the applied field which is attributed to the suppression of cycloidal spin structure. A large coupling between ferromagnetic and ferroelectric order parameters has been found at room temperature. It has been attributed to the large ferroelastic domains and suppression of the cycloid spin structure. - Highlights: ► BiFeO3 films deposited by spray pyrolysis method at low temperature ► Improved ferroelectric and ferromagnetic properties were obtained ► A strong magnetoelectric coupling was observed

  17. Stabilisation of Fe2O3-rich Perovskite Nanophase in Epitaxial Rare-earth Doped BiFeO3 Films.

    Science.gov (United States)

    Zhang, Huairuo; Reaney, Ian M; Marincel, Daniel M; Trolier-McKinstry, Susan; Ramasse, Quentin M; MacLaren, Ian; Findlay, Scott D; Fraleigh, Robert D; Ross, Ian M; Hu, Shunbo; Ren, Wei; Rainforth, W Mark

    2015-01-01

    Researchers have demonstrated that BiFeO3 exhibits ferroelectric hysteresis but none have shown a strong ferromagnetic response in either bulk or thin film without significant structural or compositional modification. When remanent magnetisations are observed in BiFeO3 based thin films, iron oxide second phases are often detected. Using aberration-corrected scanning transmission electron microscopy, atomic resolution electron energy loss spectrum-mapping and quantitative energy dispersive X-ray spectroscopy analysis, we reveal the existence of a new Fe2O3-rich perovskite nanophase, with an approximate formula (Fe0.6Bi0.25Nd0.15)(3+) Fe(3+)O3, formed within epitaxial Ti and Nd doped BiFeO3 perovskite films grown by pulsed laser deposition. The incorporation of Nd and Bi ions on the A-site and coherent growth with the matrix stabilise the Fe2O3-rich perovskite phase and preliminary density functional theory calculations suggest that it should have a ferrimagnetic response. Perovskite-structured Fe2O3 has been reported previously but never conclusively proven when fabricated at high-pressure high-temperature. This work suggests the incorporation of large A-site species may help stabilise perovskite-structured Fe2O3. This finding is therefore significant not only to the thin film but also to the high-pressure community. PMID:26272264

  18. The enhanced photocurrent of epitaxial BiFeO3 film at 130 °C

    International Nuclear Information System (INIS)

    The short-circuit photocurrent (ISC) that can be reversed by polarization switch enhances with temperature increasing to 130 °C in the epitaxial BiFeO3 thin film on SrTiO3 substrate. The La2/3Sr1/3MnO3/BiFeO3/indium tin oxide (In2O3:SnO2 = 9:1) junction shows the current rectifying characteristic and the photovoltaic effect at 20–130 °C. Importantly, the ISC can be reversed by the polarization switch in this temperature range. More charge carriers are activated and the density of free electrons enhances with the increase in the temperature, which results in the decrease in the depletion layer width. As a result, the open-circuit voltage decreases 50% and the ISC increases from 180 nA to 404 nA with the increase in the temperature from 20 °C to 130 °C. This suggests that the corresponding sensors and devices can be used at a relatively high temperature

  19. Effects of Interfaces on the Structure and Novel Physical Properties in Epitaxial Multiferroic BiFeO3 Ultrathin Films

    Directory of Open Access Journals (Sweden)

    Chuanwei Huang

    2014-07-01

    Full Text Available In functional oxide films, different electrical/mechanical boundaries near film surfaces induce rich phase diagrams and exotic phenomena. In this paper, we review some key points which underpin structure, phase transition and related properties in BiFeO3 ultrathin films. Compared with the bulk counterparts, we survey the recent results of epitaxial BiFeO3 ultrathin films to illustrate how the atomic structure and phase are markedly influenced by the interface between the film and the substrate, and to emphasize the roles of misfit strain and depolarization field on determining the domain patterns, phase transformation and associated physical properties of BiFeO3 ultrathin films, such as polarization, piezoelectricity, and magnetism. One of the obvious consequences of the misfit strain on BiFeO3 ultrathin films is the emergence of a sequence of phase transition from tetragonal to mixed tetragonal & rhombohedral, the rhombohedral, mixed rhombohedral & orthorhombic, and finally orthorhombic phases. Other striking features of this system are the stable domain patterns and the crossover of 71° and 109° domains with different electrical boundary conditions on the film surface, which can be controlled and manipulated through the depolarization field. The external field-sensitive enhancements of properties for BiFeO3 ultrathin films, including the polarization, magnetism and morphotropic phase boundary-relevant piezoelectric response, offer us deeper insights into the investigations of the emergent properties and phenomena of epitaxial ultrathin films under various mechanical/electrical constraints. Finally, we briefly summarize the recent progress and list open questions for future study on BiFeO3 ultrathin films.

  20. Effect of substrates on magnetization of BiFeO3 films

    Science.gov (United States)

    Xu, Tingting; Kan, Yi; Jin, Yaming; Lu, Xiaomei; Wu, Huarui; He, Ju; Lu, Xueliang; Zhu, Weili; Huang, Fengzhen; Zhu, Jinsong

    2015-08-01

    BiFeO3 (BFO) films were fabricated on Pt/Ti/SiO2/Si and single crystalline LiNbO3 (LN) substrates using metal organic decomposition method and annealed in N2/O2. Magnetizations of these films were systematically characterized. It is found that BFO films prepared on Pt/Ti/SiO2/Si substrates exhibit stronger saturation magnetization (MS) than those prepared on LN substrates, and their magnetizations rely more on annealing atmosphere. We consider that both oxide feature of LN substrates and in-plane compressive stress introduced by LN reduce the Fe2+ content in the top BFO films and further stabilize the films against post-treatment. This work provides a valuable guidance for fabricating high quality magnetic oxide films.

  1. Controllable growth of ultrathin BiFeO3 from finger-like nanostripes to atomically flat films

    Science.gov (United States)

    Feng, Yu; Wang, Can; Tian, Shilu; Zhou, Yong; Ge, Chen; Guo, Haizhong; He, Meng; Jin, Kuijuan; Yang, Guozhen

    2016-09-01

    BiFeO3 (BFO) ultrathin films with nominal thicknesses from 2 to 12 nm were grown with a SrRuO3 (SRO) buffer layer on TiO2-terminated (001) SrTiO3 (STO) substrates using pulsed laser deposition. The surface morphologies and domain configurations of the thin films were investigated using atomic force microscopy and piezoelectric force microscopy. Periodical one-dimensional finger-like nanostripes of BFO on the SRO covered STO substrates were observed. With increasing thickness, the BFO ultrathin films develop from the finger-like nanostripes to an atomically flat surface. The formation of the finger-like nanostructures of BFO is related to the atomic step or terrace structure of the substrate. The BFO nanostripes and the atomically flat thin films both show good ferroelectricity. The as-grown domain orientations of the BFO ultrathin films are ascribed to the chemical terminations at the surface of the SRO layer. These results indicate that the surface morphologies and the domain configurations of BFO ultrathin films can be artificially designed by using substrates with optimized terrace structures and chemical termination, and these films are potentially useful in multifunctional nanoelectronic devices.

  2. Enhanced open voltage of BiFeO3 polycrystalline film by surface modification of organolead halide perovskite

    International Nuclear Information System (INIS)

    Inorganic-organolead halide perovskite CH3NH3PbI3 modified BiFeO3 polycrystalline film has been established. The composite photoelectrode presents much larger open voltage and several magnitudes superior photoelectric conversion performance in comparison to the ordinary BiFeO3 polycrystalline film. The I-V curve shows that the short-circuit current (Jsc) is 1.74 mA·cm−2 and open-circuit voltage (Voc) is 1.62 V, the device's photon to current efficiency is over 1%. The large open voltage and high photovoltaic efficiency is believed to attributed to the spontaneous polarization of composite perovskite induced by BiFeO3 lattice and modified reduced work function of the modified BiFeO3 surface. Our results clearly show that the present BiFeO3-CH3NH3PbI3 planar device is capable to generate a large voltage in macro scale under visible light, leading an approach to further applications on photodetectors and optoelectronic switch.

  3. Domain switching in spray pyrolysis-deposited nano-crystalline BiFeO3 films

    International Nuclear Information System (INIS)

    Single-phase nano-scale BiFeO3 (BFO) films have been prepared under a controlled substrate temperature by a simple spray pyrolysis method. Fourier-transform infrared spectroscopy results indicate that single-phase BFO is deposited at low temperature. A magnetoelectric coupling to the anti-ferromagnetic and α-β phase transitions was observed at 350.2 and 832.8 °C, respectively. The capacitance-voltage (C-V) curves exhibit two coercive fields corresponding to ferroelastic (71° and 109°) and ferroelectric (180°) domains. Ferroelectric domain switching is dominant at lower electric fields. A non-volatile domain switching in the BFO films can prevent domain wall pinning and can enhance fatigue behavior in the films.

  4. Studying the Polarization Switching in Polycrystalline BiFeO3 Films by 2D Piezoresponse Force Microscopy.

    Science.gov (United States)

    Jin, Yaming; Lu, Xiaomei; Zhang, Junting; Kan, Yi; Bo, Huifeng; Huang, Fengzhen; Xu, Tingting; Du, Yingchao; Xiao, Shuyu; Zhu, Jinsong

    2015-01-01

    For rhombohedral multiferroelectrics, non-180° ferroelectric domain switching may induce ferroelastic and/or (anti-)ferromagnetic effect. So the determination and control of ferroelectric domain switching angles is crucial for nonvolatile information storage and exchange-coupled magnetoelectric devices. We try to study the intrinsic characters of polarization switching in BiFeO3 by introducing a special data processing method to determine the switching angle from 2D PFM (Piezoresponse Force Microscopy) images of randomly oriented samples. The response surface of BiFeO3 is first plotted using the piezoelectric tensor got from first principles calculations. Then from the normalized 2D PFM signals before and after switching, the switching angles of randomly oriented BiFeO3 grains can be determined through numerical calculations. In the polycrystalline BiFeO3 films, up to 34% of all switched area is that with original out-of-plane (OP) polarization parallel to the poling field. 71° polarization switching is more favorable, with the area percentages of 71°, 109° and 180° domain switching being about 42%, 29% and 29%, respectively. Our analysis further reveals that IP stress and charge migration have comparable effect on switching, and they are sensitive to the geometric arrangements. This work helps exploring a route to control polarization switching in BiFeO3, so as to realize desirable magnetoelectric coupling. PMID:26192555

  5. Pillar shape modulation in epitaxial BiFeO3–CoFe2O4 vertical nanocomposite films

    Directory of Open Access Journals (Sweden)

    Dong Hun Kim

    2014-08-01

    Full Text Available Self-assembled epitaxial CoFe2O4-BiFeO3 nanocomposite films, in which pillars of CoFe2O4 grow within a single crystal BiFeO3 matrix, show both ferrimagnetism and ferroelectricity. The pillars typically have a uniform cross-section, but here two methods are demonstrated to produce a width modulation during growth by pulsed laser deposition. This was achieved by growing a blocking layer of BiFeO3 to produce layers of separated pillars or pillars with constrictions, or by changing the temperature during growth to produce bowling-pin shaped pillars. Modulated nanocomposites showed changes in their magnetic anisotropy compared to nanocomposites with uniform width. The magnetic anisotropy was interpreted as a result of magnetoelastic and shape anisotropies.

  6. Magnetic spin structure and magnetoelectric coupling in BiFeO3-BaTiO3 multilayer

    International Nuclear Information System (INIS)

    Magnetic spin structures in epitaxial BiFeO3 single layer and an epitaxial BaTiO3/BiFeO3 multilayer thin film have been studied by means of nuclear resonant scattering of synchrotron radiation. We demonstrate a spin reorientation in the 15 × [BaTiO3/BiFeO3] multilayer compared to the single BiFeO3 thin film. Whereas in the BiFeO3 film, the net magnetic moment m→ lies in the (1–10) plane, identical to the bulk, m→ in the multilayer points to different polar and azimuthal directions. This spin reorientation indicates that strain and interfaces play a significant role in tuning the magnetic spin order. Furthermore, large difference in the magnetic field dependence of the magnetoelectric coefficient observed between the BiFeO3 single layer and multilayer can be associated with this magnetic spin reorientation

  7. Dynamics of surface screening charges on domains of BiFeO3 films

    Science.gov (United States)

    Gu, Jun-xing; Jin, Kui-juan; Ge, Chen; Ma, Chao; Yang, Guo-zhen

    2016-01-01

    The dynamics of surface screening charges on BiFeO3 films with pre-written stripe domains was studied with surface potential measurements by Kelvin Probe Force Microscopy. The screening effect decays exponentially over time, and this decay is slower in the arrays with wider domains or larger intervals of domains, indicating that the in-plane diffusion of the surface screening charges plays a major role in the decay dynamics. The good agreement between experimental data and theoretical results based on diffusion-drift model confirms the mechanism of in-plane diffusion of the screening charges in the decay dynamics. Our work could provide a pathway to control the data stability of charge storage by artificially designing the ferroelectric domains.

  8. Strong strain dependence of ferroelectric coercivity in a BiFeO3 film

    Energy Technology Data Exchange (ETDEWEB)

    Biegalski, Michael D [ORNL; Kim, Dae Ho [Tulane University; Dorr, Kathrin [IFW Dresden; Christen, Hans M [ORNL

    2011-01-01

    The ferroelectric polarization loop of an epitaxial BiFeO3 film on a piezoelectric substrate has been measured as a function of the continuously and reversibly varied biaxial strain of e = 0.36 0.51 %. Over this range, the ferroelectric coercive field (Ec) at 80 K increases reversibly by 36 % with the increasing tensile strain. The strain dependence of the remanent polarization agrees with previous experimental results and simulations based on thermodynamic considerations. In contrast, such calculations predict dEc/de <0, contradicting our experiments. Thus, the strain dependence of kinetic barriers influencing the rates of domain wall nucleation and propagation which are neglected in thermodynamic models may dominate the observed positive dEc/de.

  9. Dynamics of surface screening charges on domains of BiFeO3 films

    Directory of Open Access Journals (Sweden)

    Jun-xing Gu

    2016-01-01

    Full Text Available The dynamics of surface screening charges on BiFeO3 films with pre-written stripe domains was studied with surface potential measurements by Kelvin Probe Force Microscopy. The screening effect decays exponentially over time, and this decay is slower in the arrays with wider domains or larger intervals of domains, indicating that the in-plane diffusion of the surface screening charges plays a major role in the decay dynamics. The good agreement between experimental data and theoretical results based on diffusion-drift model confirms the mechanism of in-plane diffusion of the screening charges in the decay dynamics. Our work could provide a pathway to control the data stability of charge storage by artificially designing the ferroelectric domains.

  10. Ferroelectric domain scaling and switching in ultrathin BiFeO3 films deposited on vicinal substrates

    International Nuclear Information System (INIS)

    We report on electrically switchable polarization and ferroelectric domain scaling over a thickness range of 5-100 nm in BiFeO3 films deposited on [110] vicinal substrates. The BiFeO3 films of variable thickness were deposited with SrRuO3 bottom layer using the pulsed laser deposition technique. The domains are engineered into preferentially oriented patterns due to substrate vicinality along the [110] direction. The domain width scales closely with the square root of film thickness, in agreement with the Landau-Lifschitz-Kittel (LLK) law. Switching spectroscopy piezo-response force microscopy provides clear evidence for the ferroelectric switching behavior in all the films. (paper)

  11. Fabrication of Multiferroic Co-Substituted BiFeO3 Epitaxial Films on SrTiO3 (100 Substrates by Radio Frequency Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    Yasuo Ando

    2011-06-01

    Full Text Available The 10 at.% Co-substituted BiFeO3 films (of thickness 50 nm were successfully prepared by radio frequency (r.f. magnetron sputtering on SrTiO3 (100 substrates with epitaxial relationships of [001](001Co-BiFeO3//[001](001SrTiO3. In this study, a single phase Co-substituted BiFeO3 epitaxial film was fabricated by r.f. magnetron sputtering. Sputtering conditions such as Ar, O2 gas pressure, annealing temperature, annealing atmosphere, and sputtering power were systematically changed. It was observed that a low Ar gas pressure and low sputtering power is necessary to suppress the formation of the secondary phases of BiOx. The Co-substituted BiFeO3 films were crystalized with post-annealing at 600 °C in air. The process window for single phase films is narrower than that for pure BiFeO3 epitaxial films. By substituting Fe with Co in BiFeO3, the magnetization at room temperature increased to 20 emu/cm3. This result suggests that Co-substituted BiFeO3 films can be used in spin-filter devices.

  12. Modulating the ratio of tetragonal/rhombohedral phases in strained BiFeO3 films by varying the oxygen pressure during deposition

    Science.gov (United States)

    Staruch, Margo; Kim, Heungsoo

    2014-03-01

    Room-temperature multiferroic BiFeO3 (BFO) has been the subject of recent research interest due to its potential applications in random access memory and other spintronic devices. Compressive strain in the BFO lattice results in a symmetry change from a rhombohedral to a monoclinically-distorted tetragonal structure, with intermediate strains lying near a morphotropic phase boundary. This has been demonstrated to lead to enhanced piezoelectric and dielectric properties. However, the effect of growth conditions, such as substrate temperature and oxygen partial pressure during deposition, on the multiferroic properties of strained BFO films has yet to be systematically studied. In this work, BiFeO3 thin films were grown on (001) LaAlO3 single crystal substrates by pulsed laser deposition at different oxygen partial pressures. By examining the structure and microstructure of the resulting films, the ratio of the tetragonal-like and rhombohedral phases was found to vary with oxygen deposition pressure. The effects of this modulation on the magnetic and ferroelectric properties will be presented. This work was funded by the Office of Naval Research (ONR) through the Naval Research Laboratory Basic Research Program.

  13. Transverse photovoltaic effect of tetragonal BiFeO3 films

    Science.gov (United States)

    Gao, R. L.; Zhang, H. R.; Fu, C. L.; Cai, W.; Chen, G.; Deng, X. L.; Sun, J. R.

    2016-05-01

    Tetragonal BiFeO3 films with the thickness of 30 nm were grown epitaxially on (001) oriented LaAlO3 substrate by using pulsed laser deposition (PLD). The transverse photovoltaic effects were studied as a function of the sample directions in-plane as well as the angle between the linearly polarized light and the plane of the sample along X and Y directions. The absorption onset and the direct band gap are ~2.25 eV and ~2.52 eV, respectively. The photocurrent depends not only on the the sample directions in-plane but also on the angle between the linearly polarized light and the plane of the sample along X and Y directions. The results indicate that the bulk photovoltaic effect together with the depolarization field were ascribed to this phenomenon. Detailed analysis presents that the polarization direction is along [110] direction and this depolarization field induced photocurrent is equal to ~3.53 μA/cm2. The BPV induced photocurrent can be approximate described as Jx≈2.23cos(2θ), such an angular dependence of photocurrent is produced as a consequence of asymmetric microscopic processes of carriers such as excitation and recombination.

  14. Combined effects of Bi deficiency and Mn substitution on the structural transformation and functionality of BiFeO3 films

    International Nuclear Information System (INIS)

    Mn-doped BiFeO3 films with Mn contents of 5 and 10 mol. % were prepared via a chemical route. A carefully controlled amount of Bi deficiency was introduced to further tune the lattice structure and the functionality of multiferroic BiFeO3. The crystal structure of Bi1−δFe1−xMnxO3 films was investigated by X-ray diffraction and Raman spectra; a rhombohedral-to-orthorhombic phase transition was revealed. The observed double hysteresis loops and two capacitance maxima from polarization vs electric field and capacitance-voltage measurements indicate an antiferroelectric-like behavior. Additionally, the coexistence of ferroelectric (FE) and antiferroelectric (AFE) phases in Bi1−δFe1−xMnxO3 films was revealed from the domain structures obtained by piezoelectric force microscopy. The effects of Mn substitution in conjunction with Bi deficiency on the FE-AFE phase transition and electrical behavior of BiFeO3 films are discussed in detail. Meanwhile, magnetic and photoluminescence measurements on the films illustrate that Mn substitution gives rise to the net magnetic moment and the defects induced by both Bi deficiency and Mn substitution influence the electronic structure of BiFeO3 films. This study thus shows a simple and effective way to control the functionalities of BiFeO3 films

  15. Epitaxial strain and electric boundary condition effects on the structural and ferroelectric properties of BiFeO3 films

    OpenAIRE

    Johann, Florian; Morelli, Alessio; Biggemann, Daniel; Arredondo-Arechavala, Miryam; Vrejoiu, Ionela

    2011-01-01

    The influence of both compressive and tensile epitaxial strain along with the electrical boundary conditions on the ferroelastic and ferroelectric domain patterns of bismuth ferrite films was studied. BiFeO3 films were grown on SrTiO3(001), DyScO3(110), GdScO3(110), and SmScO3(110) substrates to investigate the effect of room temperature in-plane strain ranging from -1.4% to +0.75%. Piezoresponse force microscopy, transmission electron microscopy, x-ray diffraction measurements, and ferroelec...

  16. Influence of piezoelectric strain on the Raman spectra of BiFeO3 films deposited on PMN-PT substrates

    Science.gov (United States)

    Himcinschi, Cameliu; Guo, Er-Jia; Talkenberger, Andreas; Dörr, Kathrin; Kortus, Jens

    2016-01-01

    BiFeO3 epitaxial thin films were deposited on piezoelectric 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (PMN-PT) substrates with a conductive buffer layer (La0.7Sr0.3MnO3 or SrRuO3) using pulsed laser deposition. The calibration of the strain values induced by the electric field applied on the piezoelectric PMN-PT substrates was realised using X-Ray diffraction measurements. The method of piezoelectrically induced strain allows one to directly obtain a quantitative correlation between the strain and the shift of the Raman-active phonons. This is a prerequisite for making Raman scattering a strong tool to probe the strain coupling in multiferroic nanostructures. Using the Poisson's number for BiFeO3, one can determine the volume change induced by strain, and therefore the Grüneisen parameters for specific phonon modes.

  17. Microstructure development of BiFeO3-PbTiO3 films deposited by pulsed laser deposition on platinum substrates

    OpenAIRE

    Esat, F; Comyn, TP; Bell., AJ

    2014-01-01

    BiFeO3-PbTiO3 films around the morphotropic phase boundary were deposited by pulsed laser deposition on polycrystalline Pt/TiOx/SiO2/Si substrates. X-ray analysis confirms that 0.6BiFeO3-0.4PbTiO3 films are (0 0 1) tetragonal preferentially orientated due to lattice matching with the underlying substrate. The misfit strain at the substrate-film interface is relieved by a ∼19% orientation transformation from (0 0 1) to (1 0 0) due to the lattice mismatch at the substrate-film interface and the...

  18. Enhanced ferroelectric photoelectrochemical properties of polycrystalline BiFeO3 film by decorating with Ag nanoparticles

    Science.gov (United States)

    Liu, Qing; Zhou, Yang; You, Lu; Wang, Junling; Shen, Mingrong; Fang, Liang

    2016-01-01

    Polycrystalline BiFeO3 (BFO) films are fabricated on Pt/Ti/SiO2/Si(100) substrate as photoelectrode using sol-gel method. The microstructure, optical, and photoelectrochemical (PEC) properties of the films are characterized and optimized by controlling the film thickness. Moreover, the PEC properties of the BFO films are dependent on ferroelectric polarization, which is mainly ascribed to the modulation of band structure at the BFO/electrolyte interface by the polarization. Further enhancement of PEC properties is obtained by decorating the samples with appropriate amounts of Ag nanoparticles, which is attributed to the reduced electron-hole recombination, and localized surface plasmon resonance effect of Ag nanoparticles.

  19. Optical and electrical properties of spray pyrolysis deposited nano-crystalline BiFeO3 films

    Directory of Open Access Journals (Sweden)

    Annapu Reddy Venkateswarlu

    2011-12-01

    Full Text Available The nano-crystalline BiFeO3 were prepared under controlled substrate temperature by spray pyrolysis method. Their structural, optical and electrical properties were studied and correlated. A blueshift (Δλ ∼ 8.17 nm in the absorbance peaks was observed in the films with decrease in grain size. The absorption coefficient spectra show defect transitions at 1.9 and 2.3 eV in large grain size films due to oxygen vacancies. The lowest leakage was observed in smaller grain size (< 20 nm films due to negligible oxygen vacancies, smooth surface roughness and large energy bang gap. The Poole-Frankel conduction mechanism has been found to be the predominant mechanism for the leakage current.

  20. Heterointerface design and strain tuning in epitaxial BiFeO3:CoFe2O4 nanocomposite films

    Science.gov (United States)

    Zhang, Wenrui; Fan, Meng; Li, Leigang; Chen, Aiping; Su, Qing; Jia, Quanxi; MacManus-Driscoll, Judith L.; Wang, Haiyan

    2015-11-01

    The ability to control the morphology of heterointerfaces with coupled functionalities is fascinating from both fundamental and technological perspectives. Here, using BiFeO3:CoFe2O4 vertically aligned nanocomposite (VAN) films as a model system, we demonstrate a simple and effective method to modulate the heterointerface and its morphology in nanocomposite films with pulsed laser deposition. By tuning the deposition frequency through thickness during film growth, both vertically straight and gradient heterointerfaces have been achieved. The modulated heterointerface is strongly correlated with strain tuning and interface coupling, and thus modifies the magnetic anisotropy, coercive fields, and ferroelectric switching behavior. This study provides a viable approach for tailoring the interface strain and coupling in VAN and achieving tunable physical properties.

  1. Electrical and mechanical switching of ferroelectric polarization in the 70 nm BiFeO3 film

    Science.gov (United States)

    Chen, Liufang; Cheng, Zhihao; Xu, Wenting; Meng, Xiangjian; Yuan, Guoliang; Liu, Junming; Liu, Zhiguo

    2016-01-01

    Ferroelectric polarization switching and its domain evolution play a key role on the macroscopic electric properties of ferroelectric or piezoelectric devices. Mechanical switching has been reported recently in ~5 nm BaTiO3 and PbZr0.2Ti0.8O3 epitaxial films; however it is still a challenge for a mechanical force to switch polarization of a slightly thicker film in the same way as an electric field. Here, we report that the polarization of a 70 nm BiFeO3 epitaxial film can be completely switched by a mechanical force, and its domain evolution is similar to that observed with electrical switching. With the gradual increase of the field/force, new domains nucleate preferentially at domain boundaries, the μm-size domains commonly decompose to a mass of nm-size domains, and finally they may reorganize to μm-size domains which undergo 180o polarization switching through multi steps. Importantly, the complete mechanical switching of polarization was also established in the (0 0 1) film with a smooth surface. Furthermore, either upward or downward polarization can be read out nondestructively by a constant current. Our study sheds light on prospective applications of ferroelectrics in the absence of an electric field, such as memory devices and other micro-electromechanical systems.

  2. Magnetic Structure of Multiferroic BiFeO3 Film with Engineered Ferroelectric Domains

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, P.P [Michigan State University, East Lansing; Baek, S H [University of Wisconsin; Zarestky, Jerel L. [Ames Laboratory; Tian, Wei [Ames Laboratory and Iowa State University; Eom, C-B [HSX Laboratory, University of Wisconsin-Madison

    2010-10-01

    We report on neutron scattering and piezoresponse force microscopy studies of multiferroic BiFeO{sub 3} films epitaxially grown on vicinal SrTiO{sub 3} substrates. We find that these BiFeO{sub 3} films exhibit a G-type antiferromagnetic structure modulated with cycloidal spiral magnetic ordering with the features of magnetic domains depending upon the ferroelectric domain states: a single antiferromagnetic domain for the films with a ferroelectric monodomain while two- or multiantiferromagnetic domains existing in the films displaying two- or four-ferroelectric variants, respectively. These results imply the correlation between ferroelectric and magnetic order parameters in the BiFeO{sub 3} films and the expected strong magnetoelectric coupling makes these multiferroic films promising candidates for device applications with the capability to tune the magnetism using an electric field.

  3. Bipolar resistive switching and its temperature dependence in the composite structure of BiFeO3 bilayer

    Science.gov (United States)

    Ma, W. J.; Xiong, W. M.; Zhang, X. Y.; Wang, Ying; Zhang, H. Y.; Wang, C. Q.; Wang, Biao; Zheng, Yue

    2016-04-01

    In order to demonstrate the control of BiFeO3 thin film on the resistive switching effect and achieve the high-performance resistive switching device, the single layers and bilayer have been fabricated by chemical solution deposition method, respectively. In comparison with the single films, the composite film exhibits great performance of the resistive switching in endurance and repeatability, high stability and resistance ratio of high resistance state to low resistance state. Resistive switching effect in the BiFeO3 composite structure demonstrates an effective way to improve the endurance and repeatability of the resistive switching characteristics by designing the relative devices.

  4. Magnetization Reversal by Out-of-plane Voltage in BiFeO3-based Multiferroic Heterostructures.

    Science.gov (United States)

    Wang, J J; Hu, J M; Peng, Ren-Ci; Gao, Y; Shen, Y; Chen, L Q; Nan, C W

    2015-01-01

    Voltage controlled 180° magnetization reversal has been achieved in BiFeO3-based multiferroic heterostructures, which is promising for the future development of low-power spintronic devices. However, all existing reports involve the use of an in-plane voltage that is unfavorable for practical device applications. Here, we investigate, using phase-field simulations, the out-of-plane (i.e., perpendicular to heterostructures) voltage controlled magnetism in heterostructures consisting of CoFe nanodots and (110) BiFeO3 thin film or island. It is predicted that the in-plane component of the canted magnetic moment at the CoFe/BiFeO3 interface can be reversed repeatedly by applying a perpendicular voltage across the bottom (110) BiFeO3 thin film, which further leads to an in-plane magnetization reversal in the overlaying CoFe nanodot. The non-volatility of such perpendicular voltage controlled magnetization reversal can be achieved by etching the continuous BiFeO3 film into isolated nanoislands with the same in-plane sizes as the CoFe nanodot. The findings would provide general guidelines for future experimental and engineering efforts on developing the electric-field controlled spintronic devices with BiFeO3-based multiferroic heterostructures. PMID:25995062

  5. FAST TRACK COMMUNICATION: Ferroelectric properties and dielectric responses of multiferroic BiFeO3 films grown by RF magnetron sputtering

    Science.gov (United States)

    Qi, Xiaoding; Tsai, Po-Chou; Chen, Yi-Chun; Ko, Cheng-Hung; Huang, Jung-Chun-Andrew; Chen, In-Gann

    2008-12-01

    Multiferroic BiFeO3 films have been grown on LaNiO3-x/SrTiO3 and Pt/Si substrates by RF magnetron sputtering. The films showed fully saturated ferroelectric hysteresis loops with large remanent polarization of 64 µC cm-2, suitable for most device applications. Piezoresponse force microscopy confirmed that the films were electrically writable. In addition to the high-frequency intrinsic dielectric loss of epitaxial films, the Argand diagram also revealed low-frequency contributions from both dc conductivity and interfacial polarization at electrodes. For polycrystalline films on Pt/Si, the dominant contribution to dielectric loss was space charge polarization at grain boundaries.

  6. Control of oxygen octahedral rotation in BiFeO3 films using modulation of SrRuO3 bottom electrode layer

    Science.gov (United States)

    Lee, Sungsu; Jo, Ji Young

    2015-03-01

    Oxygen octahedral rotation of multiferroic BiFeO3 (BFO) has attracted great attention due to changes of electrical and magnetic properties. Coupling of octahedral rotation in BFO-bottom electrode layer interface remains unexplored. Recently, there have been reported the control of octahedral rotation in SrRuO3 (SRO) film on SrTiO3 (001) substrate by coherently controlling the oxygen pressure during growth and interfacial coupling. Here we demonstrate that the octahedral rotation of BFO film is changed using tetragonal a0a0c- tilted-SRO bottom electrodes. In this work, BFO/SRO heterostructure is fabricated to SrTiO3 (001) single crystal substrates by pulsed laser deposition at different oxygen partial pressures. The rotation pattern of FeO6 and the structural symmetry are identified from half-integer reflections using high-resolution X-ray diffraction. The effects depending on octahedral tilting of BFO films on the magnetic and ferroelectric properties will be presented.

  7. Oxygen diffusion and nonstoichiometry in BiFeO3.

    Science.gov (United States)

    Ito, Toshimitsu; Ushiyama, Tomoharu; Aoki, Mitsuko; Tomioka, Yasuhide; Hakuta, Yukiya; Takashima, Hiroshi; Wang, Ruiping

    2013-11-01

    Leakage current is a serious problem for the use of ferroelectricity in room-temperature multiferroics BiFeO3, and oxygen nonstoichiometry is considered as one of its principal origins. In order to establish a method to control oxygen content in the compound, we investigated the annealing process of stoichiometric BiFeO3 grains in air and revealed that oxygen diffusion occurs in two steps: (1) the weight of the sample decreases in a short time, which originates from the generation of oxygen deficiency near the surface of the grains; and then (2) it increases gradually and slowly, which originates from oxygen diffusion toward equilibrium in the inner part of the grains, introducing excess oxygen there. Step 1 causes the leakage current, and step 2 tends to cause inhomogeneity of oxygen content as well as the leakage current. Steps 1 and 2 are related to oxygen deficiency and excess oxygen often observed in thin films and bulk crystals, respectively. For the synthesis of homogeneous and highly insulating bulk sample, it is important to avoid these annealing processes, and it is a good way to grow a crystal with stoichiometric oxygen content by the control of atmospheric oxygen partial pressure and taking out its inner part. PMID:24143962

  8. Antiferromagnetic transitions in `tetragonal-like' BiFeO3

    Energy Technology Data Exchange (ETDEWEB)

    MacDougall, Gregory J [ORNL; Christen, Hans M [ORNL; Siemons, Wolter [ORNL; Biegalski, Michael D [ORNL; Zarestky, Jerel L [ORNL; Liang, Shuhua [ORNL; Dagotto, Elbio R [ORNL; Nagler, Stephen E [ORNL

    2012-01-01

    Recent studies have reported the existence of an epitaxially-stabilized tetragonal-like (`T-like') monoclinic phase in BiFeO3 thin-films with high levels of compressive strain. Though there is abundant evidence that structural and ferroelectric properties are di erent than in rhombohedral-like (`R-like') films with lower levels of strain, little information exists on magnetic properties. Here,we report a detailed neutron scattering study of a nearly phase-pure film of T-like BiFeO3. By tracking the temperature dependence and relative intensity of several superstructure peaks in the reciprocal lattice cell, we confirm antiferromagnetism with largely G-type character and T_N = 324 K. A minority magnetic phase with C-type character is also reported with T_N= 260 K. The co-existence of the two phases in T-like BiFeO3 and the difference in ordering temperatures between R-like and T-like systems is explained through simple Fe-O-Fe bond distance considerations.

  9. Antiferromagnetic transitions in 'tetragonal-like' BiFeO3

    International Nuclear Information System (INIS)

    Recent studies have reported the existence of an epitaxially-stabilized tetragonal-like ('T-like') monoclinic phase in BiFeO3 thin-films with high levels of compressive strain. Though there is abundant evidence that structural and ferroelectric properties are different than in rhombohedral-like ('R-like') films with lower levels of strain, little information exists on magnetic properties. Here,we report a detailed neutron scattering study of a nearly phase-pure film of T-like BiFeO3. By tracking the temperature dependence and relative intensity of several superstructure peaks in the reciprocal lattice cell, we confirm antiferromagnetism with largely G-type character and TN = 324 K. A minority magnetic phase with C-type character is also reported with TN = 260 K. The co-existence of the two phases in T-like BiFeO3 and the difference in ordering temperatures between R-like and T-like systems is explained through simple Fe-O-Fe bond distance considerations.

  10. Phase Coexistence near a Morphotropic Phase Boundary in Sm-doped BiFeO3 Films

    Energy Technology Data Exchange (ETDEWEB)

    S Emery; C Cheng; D Kan; F Rueckert; S Alpay; V Nagarajan; I Takeuchi; B Wells

    2011-12-31

    We have investigated heteroepitaxial films of Sm-doped BiFeO{sub 3} with a Sm-concentration near a morphotropic phase boundary. Our high-resolution synchrotron x-ray diffraction, carried out in a temperature range of 25 to 700 C, reveals substantial phase coexistence as one changes temperature to crossover from a low-temperature PbZrO{sub 3}-like phase to a high-temperature orthorhombic phase. We also examine changes due to strain for films exhibiting anisotropic misfit between film and substrate. Additionally, thicker films exhibit a substantial volume collapse associated with the structural transition that is suppressed in thinner films.

  11. Ferroelectric Domain Scaling and Switching in Ultrathin BiFeO3 Films Deposited on Vicinal Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Shelke, Vilas [University of Alabama, Tuscaloosa; Mazumdar, Dipanjan [University of Alabama, Tuscaloosa; Jesse, Stephen [ORNL; Kalinin, Sergei V [ORNL; Baddorf, Arthur P [ORNL; Gupta, Dr. Arunava [University of Alabama, Tuscaloosa

    2012-01-01

    We report on electrically switchable polarization and ferroelectric domain scaling over a thickness range of 5-100 nm in BiFeO{sub 3} films deposited on [110] vicinal substrates. The BiFeO{sub 3} films of variable thickness were deposited with SrRuO{sub 3} bottom layer using the pulsed laser deposition technique. The domains are engineered into preferentially oriented patterns due to substrate vicinality along the [110] direction. The domain width scales closely with the square root of film thickness, in agreement with the Landau-Lifschitz-Kittel (LLK) law. Switching spectroscopy piezo-response force microscopy provides clear evidence for the ferroelectric switching behavior in all the films.

  12. Simultaneous achievement of high dielectric constant and low temperature dependence of capacitance in (111)-oriented BaTiO3-Bi(Mg0.5Ti0.5)O3-BiFeO3 solid solution thin films

    Science.gov (United States)

    Kimura, Junichi; Chentir, Mohamed-Tahar; Shimizu, Takao; Uchida, Hiroshi; Funakubo, Hiroshi

    2016-01-01

    The temperature dependence of the capacitance of (111)c-oriented (0.90-x)BaTiO3-0.10Bi(Mg0.5Ti0.5)O3-xBiFeO3 solid solution films is investigated. These films are prepared on (111)cSrRuO3/(111)Pt/TiO2/SiO2/(100)Si substrates by the chemical solution deposition technique. All the films have perovskite structures and the crystal symmetry at room temperature varies with increasing x ratio, from pseudocubic when x = 0-0.30 to rhombohedral when x = 0.50-0.90. The pseudocubic phase shows a high relative dielectric constant (ɛr) (ranging between 400 and 560 at room temperature and an operating frequency of 100 kHz) and a low temperature dependence of capacitance up to 400°C, while maintaining a dielectric loss (tan δ) value of less than 0.2 at 100 kHz. In contrast, ɛr for the rhombohedral phase increases monotonically with increasing temperature up to 250°C, and increasingly high tan δ values are recorded at higher temperatures. These results indicate that pseudocubic (0.90-x)BaTiO3-0.10Bi(Mg0.5Ti0.5)O3-xBiFeO3 solid solution films with (111) orientation are suitable candidates for high-temperature capacitor applications.

  13. Simultaneous achievement of high dielectric constant and low temperature dependence of capacitance in (111-oriented BaTiO3-Bi(Mg0.5Ti0.5O3-BiFeO3 solid solution thin films

    Directory of Open Access Journals (Sweden)

    Junichi Kimura

    2016-01-01

    Full Text Available The temperature dependence of the capacitance of (111c-oriented (0.90–xBaTiO3-0.10Bi(Mg0.5Ti0.5O3-xBiFeO3 solid solution films is investigated. These films are prepared on (111cSrRuO3/(111Pt/TiO2/SiO2/(100Si substrates by the chemical solution deposition technique. All the films have perovskite structures and the crystal symmetry at room temperature varies with increasing x ratio, from pseudocubic when x = 0–0.30 to rhombohedral when x = 0.50–0.90. The pseudocubic phase shows a high relative dielectric constant (εr (ranging between 400 and 560 at room temperature and an operating frequency of 100 kHz and a low temperature dependence of capacitance up to 400°C, while maintaining a dielectric loss (tan δ value of less than 0.2 at 100 kHz. In contrast, εr for the rhombohedral phase increases monotonically with increasing temperature up to 250°C, and increasingly high tan δ values are recorded at higher temperatures. These results indicate that pseudocubic (0.90–xBaTiO3-0.10Bi(Mg0.5Ti0.5O3-xBiFeO3 solid solution films with (111 orientation are suitable candidates for high-temperature capacitor applications.

  14. Stress-induced R-MA-MC-T symmetry changes in BiFeO3 films

    Energy Technology Data Exchange (ETDEWEB)

    Christen, Hans M [ORNL; Nam, Joong Hee [Korea Institute of Ceramic Engineering and Technology; Kim, Hyun Sik [University of Warwick, UK; Hatt, Alison J [Lawrence Berkeley National Laboratory (LBNL); Spaldin, Nicola A [ETH Zurich, Switzerland

    2011-01-01

    Recent reports on epitaxial BiFeO{sub 3} films show that the crystal structure changes from nearly rhombohedral (''R like'') to nearly tetragonal (''T like'') at strains exceeding {approx}-4.5%, with the T-like structure being characterized by a highly enhanced c/a ratio. While both the R-like and the T-like phases are monoclinic, our detailed x-ray diffraction results reveal a symmetry change from M{sub A} and M{sub C} type, respectively, at this R-like-to-T-like transition. Therefore, the ferroelectric polarization is confined to different (pseudocubic) planes in the two phases. By applying additional strain or by modifying the unit-cell volume of the film by substituting Ba for Bi, the monoclinic distortion in the T-like M{sub C} phase is reduced, i.e., the system approaches a true tetragonal symmetry. Therefore, in going from bulk to highly strained films, a phase sequence of rhombohedral (R)-to-monoclinic (R-like M{sub A})-to-monoclinic (T-like M{sub C})-to-tetragonal (T) is observed. This sequence is otherwise seen only near morphotropic phase boundaries in lead-based solid-solution perovskites (i.e., near a compositionally induced phase instability), where it can be controlled by electric field, temperature, or composition. Our results now show that this evolution can occur in a lead-free, stoichiometric material and can be induced by stress alone.

  15. Strain Effects of the Structural Characteristics of Ferroelectric Transition in Single-Domain Epitaxial BiFeO3 Films

    Institute of Scientific and Technical Information of China (English)

    LIU Yang; PENG Xing-Ping

    2011-01-01

    Structural characteristics of phase transition in single-domain epitaxial BiFeOz films are studied by the Landau-Devonshire theory. It is predicted that remanent polarization shows strong strain dependence for different temperatures while spontaneous polarization is almost independent of strain over a wide temperature (0-500 °C). We also obtain the thickness dependence of the c-axis lattice parameter and Curie temperature, and make a comparison between the polarization rotation angle and the angle attributed to the structural evolution in epitaxial (001)p BiFeOa h'lms grown on SrTiO3 substrates. The theoretical results are in agreement with recent experimental and theoretical data. Our calculations show that the clamping effect should also be taken into account in order to depict the mechanism of the polarization rotation completely.%@@ Structural characteristics of phase transition in single-domain epitaxial BiFeO films are studied by the Landau- Devonshire theory.It is predicted that remanent polarization shows strong strain dependence for different tem- peratures while spontaneous polarization is almost independent of strain over a wide temperature (0-500 ℃).We also obtain the thickness dependence of the c-axis lattice parameter and Curie temperature, and make a compari- son between the polarization rotation angle and the angle attributed to the structural evolution in epitaxial (001) BiFeO films grown on SrTiO substrates.The theoretical results are in agreement with recent experimental and theoretical data.Our calculations show that the damping effect should also be taken into account in order to depict the mechanism of the poIarization rotation completely.

  16. Dependence of BiFeO3 thickness on exchange bias in BiFeO3/ Co2FeAl multiferroic structures

    Science.gov (United States)

    Zhang, X.; Zhang, D. L.; Wang, Y. H.; Miao, J.; Xu, X. G.; Jiang, Y.

    2011-01-01

    We have grown BiFeO3 (BFO) thin films with different thickness on Si/SiO2/Ti/Pt(111) substrates by pulsed laser deposition. Half-metallic Co2FeAl (CFA) films with a thickness of 5 nm were then grown on the BFO films by magnetron sputtering. Through the magnetic hysteresis loops of the BFO/CFA heterostructure, we observe a direct correlation between the thickness of the BFO film and exchange bias (EB) field. The EB field exhibits fluctuation behavior with a cyclical BFO thickness of 60 nm, which is close to the spiral modulation wavelength (62 nm) of BFO. It indicates the influence of spiral modulation on the EB in the BFO/CFA multiferroic structure.

  17. Exploring Topological Defects in Epitaxial BiFeO3 Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, Rama K [ORNL; Chen, Yi-Chun [National Cheng Kung University, Tainan, Taiwan; Tai, Hsiang-Hua [National Cheng Kung University, Tainan, Taiwan; Balke, Nina [ORNL; Wu, Pingping [Pennsylvania State University; Bhattacharya, Saswata [Pennsylvania State University, University Park, PA; Chen, Long-Qing [Pennsylvania State University; Chu, Ying-Hao [National Chiao Tung University, Hsinchu, Taiwan; Lin, I-Nan [Tamkang University (TKU), Tamsui, Taiwan; Kalinin, Sergei V [ORNL; Nagarajan, Valanoor [University of New South Wales

    2011-01-01

    Using a combination of piezoresponse force microscopy (PFM) and phase-field modeling, we demonstrate ubiquitous formation of center-type and possible ferroelectric closure domain arrangements during polarization switching near the ferroelastic domain walls in (100) oriented rhombohedral BiFeO{sub 3}. The formation of these topological defects is determined from the vertical and lateral PFM data and confirmed from the reversible changes in surface topography. These observations provide insight into the mechanisms of tip-induced ferroelastic domain control and suggest that formation of topological defect states under the action of local defect- and tip-induced fields is much more common than previously believed.

  18. Thin films

    International Nuclear Information System (INIS)

    This volume is a compilation of papers presented at the 1990 Spring Meeting of the Materials Research Society in a symposium entitled Thin Films: Stresses and Mechanical Properties II. As indicated by the title, the symposium was the second in a series, the first of which was held at the Fall Meeting in 1988. The importance of thin film mechanical properties is now recognized to the extent that basic characterization techniques such as microindentation and thin film stress measurement are performed routinely, and new characterization techniques are being developed on a daily basis. Many of the papers in the symposium dealt with the developments in these characterization methods and their application to a broad spectrum of materials such as compositionally modulated structures, ion implanted materials, optical coatings, and the numerous metals, ceramics and organics used in semiconductor device manufacture

  19. Thin Films

    Czech Academy of Sciences Publication Activity Database

    Šolcová, Olga

    Maribor: Univerza v Mariboru, 2013. [Nanofuture. Maribor (SI), 03.02.2013-07.02.2013] R&D Projects: GA TA ČR TA01020804 Institutional support: RVO:67985858 Keywords : sol-gel methods * thin films * nannomaterials Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  20. A complete strain–temperature phase diagram for BiFeO3 films on SrTiO3 and LaAlO3 (0 0 1) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Siemons, W. [Oak Ridge National Laboratory; Beekman, C. [Oak Ridge National Laboratory; MacDougall, G. J. [Oak Ridge National Laboratory; Zarestky, Jerel L. [Ames Laboratory; Nagler, S E. [Oak Ridge National Laboratory; Christen, H. M. [Oak Ridge National Laboratory

    2013-10-29

    BiFeO3 has a complex phase diagram as function of both strain and temperature, undergoing a morphotropic phase transformation under large compressive strain. Epitaxial films, grown by pulsed laser deposition, are ideal for the study of the intricate phase coexistence between multiple polymporphs. Three polymorphs have been identified in the literature. They are carefully described in this paper (labelled R', T', and S'). As both ferroelectric and magnetic properties are typically strongly linked to structural distortions, the structural, ferroelectric and magnetic transition temperatures are expected to differ between the R', T' and S' polymorphs. In this paper we present a complete strain–temperature phase diagram for each of the polymorphs.

  1. Strong perpendicular exchange bias in epitaxial La(0.7)Sr(0.3)MnO3:BiFeO3 nanocomposite films through vertical interfacial coupling.

    Science.gov (United States)

    Zhang, Wenrui; Chen, Aiping; Jian, Jie; Zhu, Yuanyuan; Chen, Li; Lu, Ping; Jia, Quanxi; MacManus-Driscoll, Judith L; Zhang, Xinghang; Wang, Haiyan

    2015-09-01

    An exchange bias effect with perpendicular anisotropy is of great interest owing to potential applications such as read heads in magnetic storage devices with high thermal stability and reduced dimensions. Here we report a novel approach for achieving perpendicular exchange bias by orienting the ferromagnetic/antiferromagnetic coupling in the vertical geometry through a unique vertically aligned nanocomposite (VAN) design. Our results demonstrate robust perpendicular exchange bias phenomena in micrometer-thick films employing a prototype material system of antiferromagnetic BiFeO3 and ferromagnetic La0.7Sr0.3MnO3. The unique response of exchange bias to a perpendicular magnetic field reveals the existence of exchange coupling along their vertical heterointerfaces, which exhibits a strong dependence on their strain states. This VAN approach enables a large selection of material systems for achieving perpendicular exchange bias, which could lead to advanced spintronic devices. PMID:26222013

  2. A complete strain–temperature phase diagram for BiFeO3 films on SrTiO3 and LaAlO3 (0 0 1) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Siemons, W. [Oak Ridge National Laboratory; Beekman, C. [Oak Ridge National Laboratory; MacDougall, G. J. [Oak Ridge National Laboratory; Zarestky, Jerel L. [Ames Laboratory; Nagler, S. E. [Oak Ridge National Laboratory; Christen, H. M. [Oak Ridge National Laboratory

    2013-12-23

    BiFeO3 has a complex phase diagram as function of both strain and temperature, undergoing a morphotropic phase transformation under large compressive strain. Epitaxial films, grown by pulsed laser deposition, are ideal for the study of the intricate phase coexistence between multiple polymporphs. Three polymorphs have been identified in the literature. They are carefully described in this paper (labelled R', T', and S'). As both ferroelectric and magnetic properties are typically strongly linked to structural distortions, the structural, ferroelectric and magnetic transition temperatures are expected to differ between the R', T' and S' polymorphs. In this paper we present a complete strain–temperature phase diagram for each of the polymorphs.

  3. Giant elastic tunability in strained BiFeO3 near an electrically induced phase transition.

    Science.gov (United States)

    Li, Q; Cao, Y; Yu, P; Vasudevan, R K; Laanait, N; Tselev, A; Xue, F; Chen, L Q; Maksymovych, P; Kalinin, S V; Balke, N

    2015-01-01

    Elastic anomalies are signatures of phase transitions in condensed matters and have traditionally been studied using various techniques spanning from neutron scattering to static mechanical testing. Here, using band-excitation elastic/piezoresponse spectroscopy, we probed sub-MHz elastic dynamics of a tip bias-induced rhombohedral-tetragonal phase transition of strained (001)-BiFeO3 (rhombohedral) ferroelectric thin films from ∼10(3) nm(3) sample volumes. Near this transition, we observed that the Young's modulus intrinsically softens by over 30% coinciding with two- to three-fold enhancement of local piezoresponse. Coupled with phase-field modelling, we also addressed the influence of polarization switching and mesoscopic structural heterogeneities (for example, domain walls) on the kinetics of this phase transition, thereby providing fresh insights into the morphotropic phase boundary in ferroelectrics. Furthermore, the giant electrically tunable elastic stiffness and corresponding electromechanical properties observed here suggest potential applications of BiFeO3 in next-generation frequency-agile electroacoustic devices, based on the utilization of the soft modes underlying successive ferroelectric phase transitions. PMID:26597483

  4. Ferroelectric and electrical characterization of multiferroic BiFeO3 at the single nanoparticle level

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, Rama K [ORNL; Bogle, K A [University of New South Wales, Sydney, Australia; Kumar, Amit [ORNL; Jesse, Stephen [ORNL; Magaraggia, R [University of Glasgow; Stamps, R [University of Glasgow; Ogale, S [National Chemical Laboratory, India; Potdar, H S [National Chemical Laboratory, India

    2011-01-01

    Ferroelectric BiFeO3 (BFO) nanoparticles deposited on epitaxial substrates of SrRuO3 (SRO) and La1xSrxMnO3 (LSMO) were studied using band excitation piezoresponse spectroscopy (BEPS), piezoresponse force microscopy (PFM), and ferromagnetic resonance (FMR). BEPS confirms that the nanoparticles are ferroelectric in nature. Switching behavior of nanoparticle clusters were studied and showed evidence for inhomogeneous switching. The dimensionality of domains within nanoparticles was found to be fractal in nature, with a dimensionality constant of 1.4, on par with ferroelectric BFO thin-films under 100 nm in thickness. Ferromagnetic resonance studies indicate BFO nanoparticles only weakly affect the magnetic response of LSMO.

  5. Thin Films

    Directory of Open Access Journals (Sweden)

    M. Benmouss

    2003-01-01

    the optical absorption are consistent with the film color changes. Finally, the optical and electrochromic properties of the films prepared by this method are compared with those of our sputtered films already studied and with other works.

  6. Interfacial effects revealed by ultrafast relaxation dynamics in BiFeO3/YBa2Cu3O7 bilayers

    Science.gov (United States)

    Springer, D.; Nair, Saritha K.; He, Mi; Lu, C. L.; Cheong, S. A.; Wu, T.; Panagopoulos, C.; Chia, Elbert E. M.; Zhu, Jian-Xin

    2016-02-01

    The temperature dependence of the relaxation dynamics in the bilayer thin film heterostructure composed of multiferroic BiFeO3 (BFO) and superconducting YBa2Cu3O7 (YBCO) grown on a (001) SrTiO3 substrate is studied by a time-resolved pump-probe technique, and compared with that of pure YBCO thin film grown under the same growth conditions. The superconductivity of YBCO is found to be retained in the heterostructure. We observe a speeding up of the YBCO recombination dynamics in the superconducting state of the heterostructure, and attribute it to the presence of weak ferromagnetism at the BFO/YBCO interface as observed in magnetization data. An extension of the Rothwarf-Taylor model is used to fit the ultrafast dynamics of BFO/YBCO, that models an increased quasiparticle occupation of the ferromagnetic interfacial layer in the superconducting state of YBCO.

  7. Interfacial effects revealed by ultrafast relaxation dynamics in BiFeO 3 / YBa 2 Cu 3 O 7 bilayers

    KAUST Repository

    Springer, D.

    2016-02-12

    The temperature dependence of the relaxation dynamics in the bilayer thin film heterostructure composed of multiferroic BiFeO3 (BFO) and superconducting YBa2Cu3O7 (YBCO) grown on a (001) SrTiO3 substrate is studied by a time-resolved pump-probe technique, and compared with that of pure YBCO thin film grown under the same growth conditions. The superconductivity of YBCO is found to be retained in the heterostructure. We observe a speeding up of the YBCO recombination dynamics in the superconducting state of the heterostructure, and attribute it to the presence of weak ferromagnetism at the BFO/YBCO interface as observed in magnetization data. An extension of the Rothwarf-Taylor model is used to fit the ultrafast dynamics of BFO/YBCO, that models an increased quasiparticle occupation of the ferromagnetic interfacial layer in the superconducting state of YBCO.

  8. Large elasto-optic effect and reversible electrochromism in multiferroic BiFeO3.

    Science.gov (United States)

    Sando, D; Yang, Yurong; Bousquet, E; Carrétéro, C; Garcia, V; Fusil, S; Dolfi, D; Barthélémy, A; Ghosez, Ph; Bellaiche, L; Bibes, M

    2016-01-01

    The control of optical fields is usually achieved through the electro-optic or acousto-optic effect in single-crystal ferroelectric or polar compounds such as LiNbO3 or quartz. In recent years, tremendous progress has been made in ferroelectric oxide thin film technology-a field which is now a strong driving force in areas such as electronics, spintronics and photovoltaics. Here, we apply epitaxial strain engineering to tune the optical response of BiFeO3 thin films, and find a very large variation of the optical index with strain, corresponding to an effective elasto-optic coefficient larger than that of quartz. We observe a concomitant strain-driven variation in light absorption-reminiscent of piezochromism-which we show can be manipulated by an electric field. This constitutes an electrochromic effect that is reversible, remanent and not driven by defects. These findings broaden the potential of multiferroics towards photonics and thin film acousto-optic devices, and suggest exciting device opportunities arising from the coupling of ferroic, piezoelectric and optical responses. PMID:26923332

  9. Large elasto-optic effect and reversible electrochromism in multiferroic BiFeO3

    Science.gov (United States)

    Sando, D.; Yang, Yurong; Bousquet, E.; Carrétéro, C.; Garcia, V.; Fusil, S.; Dolfi, D.; Barthélémy, A.; Ghosez, Ph.; Bellaiche, L.; Bibes, M.

    2016-02-01

    The control of optical fields is usually achieved through the electro-optic or acousto-optic effect in single-crystal ferroelectric or polar compounds such as LiNbO3 or quartz. In recent years, tremendous progress has been made in ferroelectric oxide thin film technology--a field which is now a strong driving force in areas such as electronics, spintronics and photovoltaics. Here, we apply epitaxial strain engineering to tune the optical response of BiFeO3 thin films, and find a very large variation of the optical index with strain, corresponding to an effective elasto-optic coefficient larger than that of quartz. We observe a concomitant strain-driven variation in light absorption--reminiscent of piezochromism--which we show can be manipulated by an electric field. This constitutes an electrochromic effect that is reversible, remanent and not driven by defects. These findings broaden the potential of multiferroics towards photonics and thin film acousto-optic devices, and suggest exciting device opportunities arising from the coupling of ferroic, piezoelectric and optical responses.

  10. Ultrafast magneto-optical spectroscopy of BiFeO3-BaTiO3 based structures

    Science.gov (United States)

    Magill, Brenden A.; Bishop, Michael; McGill, Stephen A.; Zhou, Yuon; Chopra, Anuj; Maurya, Deepam; Song, Hyun-Cheol; Priya, Shashank; Khodaparast, Giti A.

    2015-09-01

    Ultrafast optical spectroscopy can provide insight into fundamental microscopic interactions, dynamics and the coupling of several degrees of freedom. Pump/ probe studies can reveal the answer to questions like "What are the achievable switching speeds in multiferroics?", "What is the influence of the crystallographic orientation and domain states on the available switching states?", and "What is the effect of the hetrostructure on promoting the coupling between the varying field excitations?". In this presentation, we report on two color (400/800nm) ultrafast pump-probe differential reflectance spectroscopy of BiFeO3-BaTiO3 structures to probe the coupling between optical and acoustic phonons to spin waves. The data presented here is a combination of different transient reflectivity measurements to probe both the carrier and spin dynamics. The (001)-BiFeO3-BaTiO3 thin films were prepared using pulsed laser deposition on vicinal SrTiO3 substrates using La0.70 Sr0.30MnO3 bottom electrodes. Crystal orientation and topography were analyzed by x-ray diffraction and atomic force microscopy. . Our results are important to developing devices on the basis of this material system. This work was supported by the AFOSR through grant FA9550-14-1-0376,NSF-Career Award DMR-0846834, and the Virginia Tech Institute for Critical Technology and Applied Science.

  11. 100-nm-sized magnetic domain reversal by the magneto-electric effect in self-assembled BiFeO3/CoFe2O4 bilayer films.

    Science.gov (United States)

    Sone, Keita; Naganuma, Hiroshi; Ito, Masaki; Miyazaki, Takamichi; Nakajima, Takashi; Okamura, Soichiro

    2015-01-01

    A (001)-epitaxial-BiFeO3/CoFe2O4 bilayer was grown by self-assembly on SrTiO3 (100) substrates by just coating a mixture precursor solution. The thickness ratio of the bilayer could be controlled by adjusting the composition ratio. For example, a BiFeOx:CoFe2Ox = 4:1 (namely Bi4CoFe6Ox) mixture solution could make a total thickness of 110 nm divided into 85-nm-thick BiFeO3 and 25-nm-thick CoFe2O4. Self-assembly of the bilayer occurred because the perovskite BiFeO3 better matched the lattice constant (misfit approximately 1%) and crystal symmetry of the perovskite SrTiO3 than the spinel CoFe2O4 (misfit approximately 7%). The magnetic domains of the hard magnet CoFe2O4 were switched by the polarization change of BiFeO3 due to an applied vertical voltage, and the switched magnetic domain size was approximately 100 nm in diameter. These results suggest that self-assembled BiFeO3/CoFe2O4 bilayers are interesting in voltage driven nonvolatile memory with a low manufacturing cost. PMID:25906339

  12. Synthesis and characterization of Bi1−xNdxFeO3 thin films deposited using a high throughput physical vapour deposition technique

    International Nuclear Information System (INIS)

    The high throughput synthesis of BiFeO3 and rare earth doped BiFeO3 films using a modified molecular beam epitaxy technique is reported. Optimum conditions for deposition have been established and compositionally graded Bi(1−x)NdxFeO3 (x = 0.08 to 0.24) thin films have been fabricated on platinised silicon substrate (Si/SiO2/TiO2/Pt) with the aim of finding the optimum Nd dopant concentrations for enhanced piezoelectric properties. For x < 0.12, the structure and symmetry were identical to that of the R3c BiFeO3 end member. For x > 0.20, the structure and symmetry were consistent with the NdFeO3 end member (Pnma). For compositions 0.12 < x < 0.2, a gradual transition from R3c to Pnma was observed via a mixed phase region but no compositional interval could be unambiguously identified in which the intermediate PbZrO3-like structure, reported by Karimi et al. (2009) [6], existed as a single phase. Piezoresponse force microscopy remanent hysteresis measurements of the film revealed a statistical increase in the piezoelectric response at x ≈ 0.11 within the R3c region adjacent to the mixed phase field. - Highlights: ► High throughput synthesis and characterization of BiFeO3 and Nd-doped BiFeO3 films ► The piezoelectric properties of compositionally graded bismuth ferrite are studied. ► The structure and phase assemblage of Nd-doped bismuth ferrite have been studied

  13. Pyrolyzed thin film carbon

    Science.gov (United States)

    Tai, Yu-Chong (Inventor); Liger, Matthieu (Inventor); Harder, Theodore (Inventor); Konishi, Satoshi (Inventor); Miserendino, Scott (Inventor)

    2010-01-01

    A method of making carbon thin films comprises depositing a catalyst on a substrate, depositing a hydrocarbon in contact with the catalyst and pyrolyzing the hydrocarbon. A method of controlling a carbon thin film density comprises etching a cavity into a substrate, depositing a hydrocarbon into the cavity, and pyrolyzing the hydrocarbon while in the cavity to form a carbon thin film. Controlling a carbon thin film density is achieved by changing the volume of the cavity. Methods of making carbon containing patterned structures are also provided. Carbon thin films and carbon containing patterned structures can be used in NEMS, MEMS, liquid chromatography, and sensor devices.

  14. Thin film processes II

    CERN Document Server

    Kern, Werner

    1991-01-01

    This sequel to the 1978 classic, Thin Film Processes, gives a clear, practical exposition of important thin film deposition and etching processes that have not yet been adequately reviewed. It discusses selected processes in tutorial overviews with implementation guide lines and an introduction to the literature. Though edited to stand alone, when taken together, Thin Film Processes II and its predecessor present a thorough grounding in modern thin film techniques.Key Features* Provides an all-new sequel to the 1978 classic, Thin Film Processes* Introduces new topics, and sever

  15. (110)-Textured Ca-doped BiFeO3 film on refined Pt(111) electrode layer on glass substrate at reduced temperature

    Science.gov (United States)

    Chang, H. W.; Shen, C. Y.; Yuan, F. T.; Tien, S. H.; Lin, S. Y.; Chen, W. A.; Wang, C. R.; Tu, C. S.; Jen, S. U.

    2016-03-01

    Multiferroic and photovoltaic properties of polycrystalline Bi0.85Ca0.15FeO3 (BCFO) film on refined Pt(111) electrode buffered glass substrate have been studied. Optimized Pt(111) electrode layer having large grain size and smooth morphology enables the development of highly (110)-textured BCFO film at a temperature as low as 450 °C. The prepared BCFO film has dense microstructure, fine grain size, and smooth surface morphology. Good ferroelectric properties with the remanent polarization (2Pr) of 108 μC/cm2 and electrical coercive field of 405 kV/cm are achieved. Improved ferromagnetic properties with magnetization of 9.2 emu/cm3 and coercivity of 1250 Oe are also attained. Significant PV properties with open-circuit photovoltage of 0.49 V and the short-circuit photocurrent of 67.4 μA/cm2 at illumination intensity of 228 mW/cm2 are observed, which are comparable to BCFO ceramics or BFO epitaxial films.

  16. Ceramic Composite Thin Films

    Science.gov (United States)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  17. Optical and electrical properties of thin films of bismuth ferric oxide

    International Nuclear Information System (INIS)

    The bismuth ferric oxide (BFO) has caused great attention in recent years because of their multi ferric properties, making it very attractive for different technological applications. In this paper simultaneous ablation of two white (Bi and Fe2O3) was used in a reactive atmosphere (containing oxygen) to deposit thin films of BFO. The composition of the films is changed by controlling the plasma parameters such as the average kinetic energy of the ions (E p) and the plasma density (Np). The effects caused by excess of Bi and Fe in atomic structure and the optical and electrical properties of the films BiFeO3 in terms of plasma parameters were studied. The X-ray diffraction patterns of BFO samples with excess of bismuth above 2% at. They exhibited small changes in structure leading to improved levels of leakage currents compared to levels of the film with a stoichiometry close to BiFeO3 composition. These samples showed a secondary phase (Bi25FeO40 selenite type) that led to the increase in the values of band gap and resistivity as well as the improvement of the piezoelectric properties. On the other hand, the films with iron excess showed as secondary phase compounds of iron oxide (α - γ-Fe2O3) that caused increments in the conductivity and decrease in the values of band gap. The results are discussed in terms of the excesses of Bi and Fe which were correlated with the plasma parameters. (Author)

  18. Pr and Gd co-doped bismuth ferrite thin films with enhanced multiferroic properties

    Indian Academy of Sciences (India)

    Chang Chun Chen; Zi Xuan Liu; Gui Wang; Yi Lin Yan

    2014-12-01

    Pr and Gd co-modified Bi0.95−PrGd0.05FeO3 ( = 0.00, 0.05, 0.10) (BPGFO) thin films on Pt(111)/Ti/SiO2/Si(100) substrates were prepared by a sol-gel together with spin coating technique. A detailed study of electrical and magnetic properties of these thin films is reported. X-ray diffraction analysis shows that, with an increase in Pr content, the crystal structures of BPGFO thin films retain rhombohedral (R3c) symmetry accompanied by structure distortion. Polarization-electric field hysteresis loops of these thin films demonstrate that the incorporation of Pr and Gd into the Bi site of BiFeO3 thin film could enhance the ferroelectric performance. Compared to other thin films, the optimal ferroelectric behaviours in Bi0.85Pr0.1Gd0.05FeO3 thin film are ascribed to its large dielectric constant, low dissipation factor and low leakage current density. Room temperature magnetization-magnetic field curves of these thin films indicate that all the samples are of paramagnetic behaviours and the enhanced saturation magnetic properties can be found.

  19. Giant Optical Enhancement of Strain Gradient in Ferroelectric BiFeO3 Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yuelin [Argonne National Lab. (ANL), Argonne, IL (United States); Adamo, C. [Stanford Univ., CA (United States); Chen, Pice [Univ. of Wisconsin, Madison, WI (United States); Evans, Paul G. [Univ. of Wisconsin, Madison, WI (United States); Nakhmanson, Serge M. [Univ. of Connecticut, Storrs, CT (United States); Parker, William [Argonne National Lab. (ANL), Argonne, IL (United States); Rowland, Clare E. [Northwestern Univ., Evanston, IL (United States); Schaller, Richard D. [Northwestern Univ., Evanston, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States); Schlom, Darrell G. [Cornell Univ., Ithaca, NY (United States); Cornell Univ., Ithaca, NY (United States). Kavli Inst. for Nanoscale Science; Walko, Donald A. [Argonne National Lab. (ANL), Argonne, IL (United States); Wen, Haidan [Argonne National Lab. (ANL), Argonne, IL (United States); Zhang, Qingteng [Univ. of Wisconsin, Madison, WI (United States)

    2015-11-20

    Through mapping of the spatiotemporal strain profile in ferroelectric BiFeO3 epitaxial thin films, we report an optically initiated dynamic enhancement of the strain gradient of 105–106 m-1 that lasts up to a few ns depending on the film thickness. Correlating with transient optical absorption measurements, the enhancement of the strain gradient is attributed to a piezoelectric effect driven by a transient screening field mediated by excitons. These findings not only demonstrate a new possible way of controlling the flexoelectric effect, but also reveal the important role of exciton dynamics in photostriction and photovoltaic effects in ferroelectrics.

  20. Carbon thin film thermometry

    Science.gov (United States)

    Collier, R. S.; Sparks, L. L.; Strobridge, T. R.

    1973-01-01

    The work concerning carbon thin film thermometry is reported. Optimum film deposition parameters were sought on an empirical basis for maximum stability of the films. One hundred films were fabricated for use at the Marshall Space Flight Center; 10 of these films were given a precise quasi-continuous calibration of temperature vs. resistance with 22 intervals between 5 and 80 K using primary platinum and germanium thermometers. Sensitivity curves were established and the remaining 90 films were given a three point calibration and fitted to the established sensitivity curves. Hydrogen gas-liquid discrimination set points are given for each film.

  1. Biomimetic thin film synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Graff, G.L.; Campbell, A.A.; Gordon, N.R.

    1995-05-01

    The purpose of this program is to develop a new process for forming thin film coatings and to demonstrate that the biomimetic thin film technology developed at PNL is useful for industrial applications. In the biomimetic process, mineral deposition from aqueous solution is controlled by organic functional groups attached to the underlying substrate surface. The coatings process is simple, benign, inexpensive, energy efficient, and particularly suited for temperature sensitive substrate materials (such as polymers). In addition, biomimetic thin films can be deposited uniformly on complex shaped and porous substrates providing a unique capability over more traditional line-of-sight methods.

  2. The origin of enhanced optical absorption of the BiFeO3/ZnO heterojunction in the visible and terahertz regions.

    Science.gov (United States)

    Feng, Hong-Jian; Yang, Kang; Deng, Wan; Li, Mengmeng; Wang, Mingzi; Duan, Bi; Liu, Feng; Tian, Jinshou; Guo, Xiaohui

    2015-10-28

    Optical absorption is improved for the BiFeO3/ZnO heterostructure prepared by a sol-gel process, especially, in the terahertz energy region. A dipole-corrected slab model is used to describe the bilayer film, and first-principles calculations agree with the experiments which present unambiguous explanation for the enhancement of the optical properties. Two-dimensional electrons in the ZnO side of the heterostructure are found to play an essential role in forming the photoinduced carriers and the enhancement of the absorption. The conducting layers tend to penetrate into the interface and decrease the band gap, leading to the transport of carriers through the interface to the BiFeO3 side. The photoinduced carriers can be separated by the ferroelectric domains in BiFeO3, and this mechanism makes the heterostructure an ideal candidate for BiFeO3-based ferroelectric photovoltaic cells. PMID:26403497

  3. Thin film device applications

    CERN Document Server

    Kaur, Inderjeet

    1983-01-01

    Two-dimensional materials created ab initio by the process of condensation of atoms, molecules, or ions, called thin films, have unique properties significantly different from the corresponding bulk materials as a result of their physical dimensions, geometry, nonequilibrium microstructure, and metallurgy. Further, these characteristic features of thin films can be drasti­ cally modified and tailored to obtain the desired and required physical characteristics. These features form the basis of development of a host of extraordinary active and passive thin film device applications in the last two decades. On the one extreme, these applications are in the submicron dimensions in such areas as very large scale integration (VLSI), Josephson junction quantum interference devices, magnetic bubbles, and integrated optics. On the other extreme, large-area thin films are being used as selective coatings for solar thermal conversion, solar cells for photovoltaic conver­ sion, and protection and passivating layers. Ind...

  4. Ferroelectric thin films

    International Nuclear Information System (INIS)

    The area of ferroelectric thin films has expanded rapidly recently with the advent of high quality multi-oxide deposition technology. Advances in thin film quality has resulted in the realization of new technologies not achievable through classical bulk ceramic processing techniques. An example of this progress is the co-processing of ferroelectric thin films with standard semiconductor silicon and GaAs integrated circuits for radiation hard, non-volatile memory products. While the development of this class of products is still embryonic, the forecasted market potential is rapidly out distancing the combined developmental effort. Historically the greatest use of bulk ferroelectric material has been in sensor technology, utilizing the pyroelectric and piezoelectric properties of the material. By comparison, a relatively small development effort has been reported for ferroelectric thin film senor technology, a field sure to provide exciting advances in the future. The papers in this proceedings volume were presented at the first symposium dedicated to the field of ferroelectric thin films held by the Materials Research Society at the Spring 1990 Meeting in San Francisco, CA, April 16-20, 1990. The symposium was designed to provide a comprehensive tutorial covering the newest advances of ferroelectric thin films, including material systems, new deposition techniques and physical, electrical and electro-optic characterization

  5. Multifunctional dual-tunable multiferroic Ba0.25Sr0.75TiO3-BiFeO3-Ba0.25Sr0.75TiO3 trilayered structure for tunable microwave applications

    International Nuclear Information System (INIS)

    A multiferroic trilayered structure composed of a BiFeO3 (BFO) layer and two Ba0.25Sr0.75TiO3 (BST) layers is grown on a Pt/TiO2/SiO2/Si substrate by pulsed laser deposition. The trilayered BST/BFO/BST thin film structure exhibits a significant tuning response for the dielectric constant with an electric field and a magnetic field, respectively. Microwave devices based on such multifunctional materials can offer dual, i.e. electric and magnetic, tuning possibility and extra flexibility in designing and shaping the device performances.

  6. Synthesis of BiFeO3 by carbonate precipitation

    Indian Academy of Sciences (India)

    V Kothai; Rajeev Ranjan

    2012-04-01

    Magnetoelectric multiferroic BiFeO3 (BFO) was synthesized by a simple carbonate precipitation technique of metal nitrate solutions. X-ray powder diffraction and thermo-gravimetric analysis (TGA) revealed that the precipitate consists of an intimate mixture of crystalline bismuth carbonate and an amorphous hydroxide of iron. The precipitate yielded BiFeO3 at an optimal calcination temperature of ∼560°C. Energy dispersive X-ray (EDX) analysis showed 1:1 ratio between Bi and Fe in the oxide. X-ray photoelectron spectroscopy (XPS) studies confirmed that Fe to be in +3 oxidation states both in the precipitated powder and BiFeO3. The synthesized BFO exhibits a very weak ferromagnetic correlation at room temperature and the degree of which increases slightly on cooling down to 10 K suggesting alteration in the long range spatial modulation of the spins arrangement as compared to the bulk BiFeO3.

  7. Negative magnetostrictive magnetoelectric coupling of BiFeO3

    OpenAIRE

    Lee, Sanghyun; Fernandez-Diaz, M. T.; H. Kimura; Noda, Y.; Adroja, D. T.; Lee, Seongsu; Park, Junghwan; Kiryukhin, V.; Cheong, S.-W.; Mostovoy, M; Park, Je-Geun

    2013-01-01

    How the magnetoelectric coupling actually occurs on a microscopic level in multiferroic BiFeO3 is not well known. By using the high-resolution single crystal neutron diffraction techniques, we have determined the electric polarization of each individual elements of BiFeO3, and concluded that the magnetostrictive coupling suppresses the electric polarization at the Fe site below TN. This negative magnetoelectric coupling appears to outweigh the spin current contributions arising from the cyclo...

  8. Evaporated VOx Thin Films

    Science.gov (United States)

    Stapinski, Tomasz; Leja, E.

    1989-03-01

    VOx thin films on glass were obtained by thermal evaporation of V205, powder. The structural investigations were carried out with the use of X-ray diffractometer. The electrical properties of the film were examined by means of temperature measurements of resistivity for the samples heat-treated in various conditions. Optical transmission and reflection spectra of VOX films of various composition showed the influence of the heat treatment.

  9. Measurement of transient atomic displacements in thin films with picosecond and femtometer resolution.

    Science.gov (United States)

    Kozina, M; Hu, T; Wittenberg, J S; Szilagyi, E; Trigo, M; Miller, T A; Uher, C; Damodaran, A; Martin, L; Mehta, A; Corbett, J; Safranek, J; Reis, D A; Lindenberg, A M

    2014-05-01

    We report measurements of the transient structural response of weakly photo-excited thin films of BiFeO3, Pb(Zr,Ti)O3, and Bi and time-scales for interfacial thermal transport. Utilizing picosecond x-ray diffraction at a 1.28 MHz repetition rate with time resolution extending down to 15 ps, transient changes in the diffraction angle are recorded. These changes are associated with photo-induced lattice strains within nanolayer thin films, resolved at the part-per-million level, corresponding to a shift in the scattering angle three orders of magnitude smaller than the rocking curve width and changes in the interlayer lattice spacing of fractions of a femtometer. The combination of high brightness, repetition rate, and stability of the synchrotron, in conjunction with high time resolution, represents a novel means to probe atomic-scale, near-equilibrium dynamics. PMID:26798776

  10. Measurement of transient atomic displacements in thin films with picosecond and femtometer resolution

    Directory of Open Access Journals (Sweden)

    M. Kozina

    2014-05-01

    Full Text Available We report measurements of the transient structural response of weakly photo-excited thin films of BiFeO3, Pb(Zr,TiO3, and Bi and time-scales for interfacial thermal transport. Utilizing picosecond x-ray diffraction at a 1.28 MHz repetition rate with time resolution extending down to 15 ps, transient changes in the diffraction angle are recorded. These changes are associated with photo-induced lattice strains within nanolayer thin films, resolved at the part-per-million level, corresponding to a shift in the scattering angle three orders of magnitude smaller than the rocking curve width and changes in the interlayer lattice spacing of fractions of a femtometer. The combination of high brightness, repetition rate, and stability of the synchrotron, in conjunction with high time resolution, represents a novel means to probe atomic-scale, near-equilibrium dynamics.

  11. Domain wall conductivity in semiconducting hexagonal ferroelectric TbMnO3 thin films

    Science.gov (United States)

    Kim, D. J.; Connell, J. G.; Seo, S. S. A.; Gruverman, A.

    2016-04-01

    Although enhanced conductivity of ferroelectric domain boundaries has been found in BiFeO3 and Pb(Zr,Ti)O3 films as well as hexagonal rare-earth manganite single crystals, the mechanism of the domain wall conductivity is still under debate. Using conductive atomic force microscopy, we observe enhanced conductance at the electrically-neutral domain walls in semiconducting hexagonal ferroelectric TbMnO3 thin films where the structure and polarization direction are strongly constrained along the c-axis. This result indicates that domain wall conductivity in ferroelectric rare-earth manganites is not limited to charged domain walls. We show that the observed conductivity in the TbMnO3 films is governed by a single conduction mechanism, namely, the back-to-back Schottky diodes tuned by the segregation of defects.

  12. Heterogeneity in Polymer Thin Films

    OpenAIRE

    Kanaya, Toshiji; Inoue, Rintaro; Nishida, Koji

    2011-01-01

    In the last two decades very extensive studies have been performed on polymer thin films to reveal very interesting but unusual properties. One of the most interesting findings is the decrease in glass transition temperature Tg with film thickness in polystyrene (PS) thin film supported on Si substrate. Another interesting finding is apparent negative thermal expansivity in glassy state for thin films below ∼25 nm. In order to understand the unusual properties of polymer thin films we have st...

  13. Thin films and nanomaterials

    International Nuclear Information System (INIS)

    The objective of this book is to disseminate the most recent research in Thin Films, Nanomaterials, Corrosion and Metallurgy presented at the International Conference on Advanced Materials (ICAM 2011) held in PSG College of Technology, Coimbatore, India during 12-16 December 2011. The book is a compilation of 113 chapters written by active researchers providing information and critical insights into the recent advancements that have taken place. Important new applications are possible today in the fields of microelectronics, opto-electronics, metallurgy and energy by the application of thin films on solid surfaces. Recent progress in high vacuum technology and new materials has a remarkable effect in thin film quality and cost. This has led to the development of new single or multi-layered thin film devices with diverse applications in a multitude of production areas, such as optics, thermal barrier coatings and wear protections, enhancing service life of tools and to protect materials against thermal and atmospheric influence. On the other hand, thin film process techniques and research are strongly related to the basic research activities in nano technology, an increasingly important field with countless opportunities for applications due to the emergence of new properties at the nanoscale level. Materials and structures that are designed and fabricated at the nano scale level, offer the potential to produce new devices and processes that may enhance efficiencies and reduce costs in many areas, as photovoltaic systems, hydrogen storage, fuel cells and solar thermal systems. In the book, the contributed papers are classified under two sections i) thin films and ii) nanomaterials. The thin film section includes single or multi layer conducting, insulating or semiconducting films synthesized by a wide variety of physical or chemical techniques and characterized or analyzed for different applications. The nanomaterials section deals with novel or exciting materials

  14. Thin film photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Zweibel, K; Ullal, H S

    1989-05-01

    Thin films are considered a potentially attractive technological approach to making cost-effective electricity by photovoltaics. Over the last twenty years, many have been investigated and some (cadmium telluride, copper indium diselenide, amorphous silicon) have become leading candidates for future large-scale commercialization. This paper surveys the past development of these key thin films and gives their status and future prospects. In all cases, significant progress toward cost-effective PV electricity has been made. If this progress continues, it appears that thin film PV could provide electricity that is competitive for summer daytime peaking power requirements by the middle of the 1990s; and electricity in a range that is competitive with fossil fuel costs (i.e., 6 cents/kilowatt-hour) should be available from PV around the turn of the century. 22 refs., 9 figs.

  15. Thin film temperature sensor

    Science.gov (United States)

    Grant, H. P.; Przybyszewski, J. S.

    1980-01-01

    Thin film surface temperature sensors were developed. The sensors were made of platinum-platinum/10 percent rhodium thermocouples with associated thin film-to-lead wire connections and sputtered on aluminum oxide coated simulated turbine blades for testing. Tests included exposure to vibration, low velocity hydrocarbon hot gas flow to 1250 K, and furnace calibrations. Thermal electromotive force was typically two percent below standard type S thermocouples. Mean time to failure was 42 hours at a hot gas flow temperature of 1250 K and an average of 15 cycles to room temperature. Failures were mainly due to separation of the platinum thin film from the aluminum oxide surface. Several techniques to improve the adhesion of the platinum are discussed.

  16. Thin Film Microbatteries

    International Nuclear Information System (INIS)

    Thin film batteries are built layer by layer by vapor deposition. The resulting battery is formed of parallel plates, much as an ordinary battery construction, just much thinner. The figure (Fig. 1) shows an example of a thin film battery layout where films are deposited symmetrically onto both sides of a supporting substrate. The full stack of films is only 10 to 15 (micro)m thick, but including the support at least doubles the overall battery thickness. When the support is thin, the entire battery can be flexible. At least six companies have commercialized or are very close to commercializing such all-solid-state thin film batteries and market research predicts a growing market and a variety of applications including sensors, RFID tags, and smarter cards. In principle with a large deposition system, a thin film battery might cover a square meter, but in practice, most development is targeting individual cells with active areas less than 25 cm2. For very small battery areas, 2, microfabrication processes have been developed. Typically the assembled batteries have capacities from 0.1 to 5 mAh. The operation of a thin film battery is depicted in the schematic diagram (Fig. 2). Very simply, when the battery is allowed to discharge, a Li+ ion migrates from the anode to the cathode film by diffusing through the solid electrolyte. When the anode and cathode reactions are reversible, as for an intercalation compound or alloy, the battery can be recharged by reversing the current. The difference in the electrochemical potential of the lithium determines the cell voltage. Most of the thin films used in current commercial variations of this thin film battery are deposited in vacuum chambers by RF and DC magnetron sputtering and by thermal evaporation onto unheated substrates. In addition, many publications report exploring a variety of other physical and chemical vapor deposition processes, such as pulsed laser deposition, electron cyclotron resonance sputtering, and

  17. Thin film ceramic thermocouples

    Science.gov (United States)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  18. Size dependent structural, vibrational and magnetic properties of BiFeO3 and core-shell structured BiFeO3@SiO2 nanoparticles

    International Nuclear Information System (INIS)

    Bulk BiFeO3, BiFeO3 nanoparticles and core-shell structured BiFeO3@SiO2 nanoparticles were synthesized by solid state reaction method, sol-gel and Stöber process (SiO2 shell) respectively. Transmission electron microscopy image confirmed the core-shell structure of BiFeO3@SiO2 nanoparticles with BiFeO3 core ∼50-90 nm and SiO2 shell ∼16 nm. X-ray diffraction and FTIR spectroscopy results showed the presence of distorted rhombohedral structure with R3c space group in all three samples. The magnetic measurement indicated the existence of room-temperature weak ferromagnetism in core-shell BiFeO3@SiO2 nanoparticles and BiFeO3 nanoparticles, whereas bulk BiFeO3 showed antiferromagnteic nature. Electron Spin Resonance results confirmed the enhancement in magnetic properties of coreshell structured BiFeO3@SiO2 nanoparticles in comparison with BiFeO3 nanoparticles and bulk BiFeO3

  19. Thin film metal-oxides

    CERN Document Server

    Ramanathan, Shriram

    2009-01-01

    Presents an account of the fundamental structure-property relations in oxide thin films. This title discusses the functional properties of thin film oxides in the context of applications in the electronics and renewable energy technologies.

  20. Thin films for material engineering

    Science.gov (United States)

    Wasa, Kiyotaka

    2016-07-01

    Thin films are defined as two-dimensional materials formed by condensing one by one atomic/molecular/ionic species of matter in contrast to bulk three-dimensional sintered ceramics. They are grown through atomic collisional chemical reaction on a substrate surface. Thin film growth processes are fascinating for developing innovative exotic materials. On the basis of my long research on sputtering deposition, this paper firstly describes the kinetic energy effect of sputtered adatoms on thin film growth and discusses on a possibility of room-temperature growth of cubic diamond crystallites and the perovskite thin films of binary compound PbTiO3. Secondly, high-performance sputtered ferroelectric thin films with extraordinary excellent crystallinity compatible with MBE deposited thin films are described in relation to a possible application for thin-film MEMS. Finally, the present thin-film technologies are discussed in terms of a future material science and engineering.

  1. Rare Earth Oxide Thin Films

    CERN Document Server

    Fanciulli, Marco

    2007-01-01

    Thin rare earth (RE) oxide films are emerging materials for microelectronic, nanoelectronic, and spintronic applications. The state-of-the-art of thin film deposition techniques as well as the structural, physical, chemical, and electrical properties of thin RE oxide films and of their interface with semiconducting substrates are discussed. The aim is to identify proper methodologies for the development of RE oxides thin films and to evaluate their effectiveness as innovative materials in different applications.

  2. Selective inorganic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, M.L.F.; Weisenbach, L.A.; Anderson, M.T. [Sandia National Laboratories, Albuquerque, NM (United States)] [and others

    1995-05-01

    This project is developing inorganic thin films as membranes for gas separation applications, and as discriminating coatings for liquid-phase chemical sensors. Our goal is to synthesize these coatings with tailored porosity and surface chemistry on porous substrates and on acoustic and optical sensors. Molecular sieve films offer the possibility of performing separations involving hydrogen, air, and natural gas constituents at elevated temperatures with very high separation factors. We are focusing on improving permeability and molecular sieve properties of crystalline zeolitic membranes made by hydrothermally reacting layered multicomponent sol-gel films deposited on mesoporous substrates. We also used acoustic plate mode (APM) oscillator and surface plasmon resonance (SPR) sensor elements as substrates for sol-gel films, and have both used these modified sensors to determine physical properties of the films and have determined the sensitivity and selectivity of these sensors to aqueous chemical species.

  3. Protein Thin Film Machines

    OpenAIRE

    Federici, Stefania; Oliviero, Giulio; Hamad-Schifferli, Kimberly; Bergese, Paolo

    2010-01-01

    We report the first example of microcantilever beams that are reversibly driven by protein thin film machines fuelled by cycling the salt concentration of the surrounding solution. We also show that upon the same salinity stimulus the drive can be completely reversed in its direction by introducing a surface coating ligand. Experimental results are throughout discussed within a general yet simple thermodynamic model.

  4. Thin film scintillators

    Science.gov (United States)

    McDonald, Warren; McKinney, George; Tzolov, Marian

    2015-03-01

    Scintillating materials convert energy flux (particles or electromagnetic waves) into light with spectral characteristic matching a subsequent light detector. Commercial scintillators such as yttrium aluminum garnet (YAG) and yttrium aluminum perovskite (YAP) are commonly used. These are inefficient at lower energies due to the conductive coating present on their top surface, which is needed to avoid charging. We hypothesize that nano-structured thin film scintillators will outperform the commercial scintillators at low electron energies. We have developed alternative thin film scintillators, zinc tungstate and zinc oxide, which show promise for higher sensitivity to lower energy electrons since they are inherently conductive. Zinc tungstate films exhibit photoluminescence quantum efficiency of 74%. Cathodoluminescence spectroscopy was applied in transmission and reflection geometries. The comparison between the thin films and the YAG and YAP commercial scintillators shows much higher light output from the zinc tungstate and zinc oxide at electron energies less than 5 keV. Our films were integrated in a backscattered electron detector. This detector delivers better images than an identical detector with commercial YAG scintillator at low electron energies. Dr. Nicholas Barbi from PulseTor LLC, Dr. Anura Goonewardene, NSF Grants: #0806660, #1058829, #0923047.

  5. Anharmonic phonons and magnons in BiFeO3

    International Nuclear Information System (INIS)

    The phonon density of states (DOS) and magnetic excitation spectrum of polycrystalline BiFeO3 were measured for temperatures 200 < T < 750K, using inelastic neutron scattering (INS). Our results indicate that the magnetic spectrum of BiFeO3 closely resembles that of similar Fe perovskites, such as LaFeO3, despite the cycloid modulation in BiFeO3. We do not find any evidence for a spin gap. A strong T-dependence of the phonon DOS was found, with a marked broadening of the whole spectrum, providing evidence of strong anharmonicity. This anharmonicity is corroborated by large amplitude motions of Bi and O ions observed with neutron diffraction. These results highlight the importance of spin-phonon coupling in this material.

  6. Anharmonic phonons and magnons in BiFeO3

    Energy Technology Data Exchange (ETDEWEB)

    Delaire, Olivier A [ORNL; Ma, Jie [ORNL; Stone, Matthew B [ORNL; Huq, Ashfia [ORNL; Gout, Delphine J [ORNL; Brown, Craig [National Institute of Standards and Technology (NIST); Wang, Kefeng [Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing; Ren, Zhifeng [Boston College, Chestnut Hill

    2012-01-01

    The phonon density of states (DOS) and magnetic excitation spectrum of polycrystalline BiFeO3 were measured for temperatures 200 < T < 750K , using inelastic neutron scattering (INS). Our results indicate that the magnetic spectrum of BiFeO3 closely resembles that of similar Fe perovskites, such as LaFeO3, despite the cycloid modulation in BiFeO3. We do not find any evidence for a spin gap. A strong T-dependence of the phonon DOS was found, with a marked broadening of the whole spectrum, providing evidence of strong anharmonicity. This anharmonicity is corroborated by large amplitude motions of Bi and O ions observed with neutron diffraction. These results highlight the importance of spin-phonon coupling in this material.

  7. Magnetic hysteresis of cerium doped bismuth ferrite thin films

    International Nuclear Information System (INIS)

    The influence of Cerium doping on the structural and magnetic properties of BiFeO3 thin films have been investigated. Rietveld refinement of X-ray diffraction data and successive de-convolution of Raman scattering spectra of Bi1−xCexFeO3 (BCFO) thin films with x=0–0.20 reflect the single phase rhombohedral (R3c) formation for x<0.08, whereas concentration-driven gradual structural phase transition from rhombohedral (R3c) to partial tetragonal (P4mm) phase follows for x≥0.08. All low wavenumber Raman modes (<300 cm−1) showed a noticeable shift towards higher wavenumber with increase in doping concentration, except Raman E-1 mode (71 cm−1), shows a minor shift. Sudden evolution of Raman mode at 668 cm−1, manifested as A1-tetragonal mode, accompanied by the shift to higher wavenumber with increase in doping concentration (x) affirm partial structural phase transition. Anomalous wasp waist shaped (M–H) hysteresis curves with improved saturation magnetization (Ms) for BCFO thin films is attributed to antiferromagnetic interaction/hybridization between Ce 4f and Fe 3d electronic states. The contribution of both hard and soft phase to the total coercivity is calculated. Polycrystalline Bi0.88Ce0.12FeO3 thin film found to exhibit better magnetic properties with Ms=15.9 emu/g without any impure phase. - Highlights: • Synthesis of single phase Bi1−xCexFeO3 thin films with (x=0–0.2) on cost effective corning glass and silicon substrates using CSD technique. • Structural modification studies using Rietveld refinement of XRD and de-convolution of Raman spectra revealed partial phase transition from rhombohedral (R3c) to tetragonal (P4mm) phase. • Possible reasons for origin of pinched magnetic behavior of BCFO thin films are identified. • Contribution of both hard and soft magnetic phase in coercivity of BCFO thin films is calculated and practical applications of such materials exhibiting pinching behavior are conferred

  8. Physics of thin films

    Energy Technology Data Exchange (ETDEWEB)

    Francombe, M.H. (Dept. of Physics, Univ. of Pittsburgh, Pittsburgh, PA (US)); Vossen, J.L. (John Vossen Associates, Technical and Scientific Consulting, Bridgewater, NJ (US))

    1992-01-01

    This book of Physics of Thin Films emphasizes two main technical themes. The first is essentially an extension of the topical thrust on Thin Films for Advance Electronic Devices, developed in Volume 15 of this series. The second deals primarily with the physical and mechanical behavior of films and the influence of these in relation to various applications. The first of the four articles in this volume, by Neelkanth G. Dhere, discusses high-transition-temperature (T{sub c}) superconducting films. Since their discovery in 1986, both world-wide research activity and published literature on high-T{sub c} oxide films have exploded at a phenomenal rate. In his treatment, the author presents an effective survey of the already vast literature on this subject, discusses the numerous techniques under development for the growth of these perovskite-related complex oxides, and describes their key properties and applications. In particular, factors affecting the epitaxial structure, critical current capability, and microwave conductivity in Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O based film compositions are evaluated in relation to their use at 77K. An overview of potential applications in a variety of microwave devices, wide-band optical detectors, SQUID-type high-sensitivity magnetometers, etc., is included.

  9. Physics of thin films

    International Nuclear Information System (INIS)

    This book of Physics of Thin Films emphasizes two main technical themes. The first is essentially an extension of the topical thrust on Thin Films for Advance Electronic Devices, developed in Volume 15 of this series. The second deals primarily with the physical and mechanical behavior of films and the influence of these in relation to various applications. The first of the four articles in this volume, by Neelkanth G. Dhere, discusses high-transition-temperature (Tc) superconducting films. Since their discovery in 1986, both world-wide research activity and published literature on high-Tc oxide films have exploded at a phenomenal rate. In his treatment, the author presents an effective survey of the already vast literature on this subject, discusses the numerous techniques under development for the growth of these perovskite-related complex oxides, and describes their key properties and applications. In particular, factors affecting the epitaxial structure, critical current capability, and microwave conductivity in Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O based film compositions are evaluated in relation to their use at 77K. An overview of potential applications in a variety of microwave devices, wide-band optical detectors, SQUID-type high-sensitivity magnetometers, etc., is included

  10. Thin film superconductor magnetic bearings

    Science.gov (United States)

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  11. Biomimetic thin film deposition

    Energy Technology Data Exchange (ETDEWEB)

    Rieke, P.R.; Graff, G.E.; Campbell, A.A.; Bunker, B.C.; Baskaran, S.; Song, L.; Tarasevich, B.J.; Fryxell, G.E.

    1995-09-01

    Biological mineral deposition for the formation of bone, mollusk shell and other hard tissues provides materials scientists with illustrative materials processing strategies. This presentation will review the key features of biomineralization and how these features can be of technical importance. We have adapted existing knowledge of biomineralization to develop a unique method of depositing inorganic thin films and coating. Our approach to thin film deposition is to modify substrate surfaces to imitate the proteins found in nature that are responsible for controlling mineral deposition. These biomimetic surfaces control the nucleation and growth of the mineral from a supersaturated aqueous solution. This has many processing advantages including simple processing equipment, environmentally benign reagents, uniform coating of highly complex shapes, and enhanced adherence of coating. Many different types of metal oxide, hydroxide, sulfide and phosphate materials with useful mechanical, optical, electronic and biomedical properties can be deposited.

  12. Thin film processes

    CERN Document Server

    Vossen, John L

    1978-01-01

    Remarkable advances have been made in recent years in the science and technology of thin film processes for deposition and etching. It is the purpose of this book to bring together tutorial reviews of selected filmdeposition and etching processes from a process viewpoint. Emphasis is placed on the practical use of the processes to provide working guidelines for their implementation, a guide to the literature, and an overview of each process.

  13. Handbook of thin film technology

    CERN Document Server

    Frey, Hartmut

    2015-01-01

    “Handbook of Thin Film Technology” covers all aspects of coatings preparation, characterization and applications. Different deposition techniques based on vacuum and plasma processes are presented. Methods of surface and thin film analysis including coating thickness, structural, optical, electrical, mechanical and magnetic properties of films are detailed described. The several applications of thin coatings and a special chapter focusing on nanoparticle-based films can be found in this handbook. A complete reference for students and professionals interested in the science and technology of thin films.

  14. Thin film mechanics

    Science.gov (United States)

    Cooper, Ryan C.

    This doctoral thesis details the methods of determining mechanical properties of two classes of novel thin films suspended two-dimensional crystals and electron beam irradiated microfilms of polydimethylsiloxane (PDMS). Thin films are used in a variety of surface coatings to alter the opto-electronic properties or increase the wear or corrosion resistance and are ideal for micro- and nanoelectromechanical system fabrication. One of the challenges in fabricating thin films is the introduction of strains which can arise due to application techniques, geometrical conformation, or other spurious conditions. Chapters 2-4 focus on two dimensional materials. This is the intrinsic limit of thin films-being constrained to one atomic or molecular unit of thickness. These materials have mechanical, electrical, and optical properties ideal for micro- and nanoelectromechanical systems with truly novel device functionality. As such, the breadth of applications that can benefit from a treatise on two dimensional film mechanics is reason enough for exploration. This study explores the anomylously high strength of two dimensional materials. Furthermore, this work also aims to bridge four main gaps in the understanding of material science: bridging the gap between ab initio calculations and finite element analysis, bridging the gap between ab initio calculations and experimental results, nanoscale to microscale, and microscale to mesoscale. A nonlinear elasticity model is used to determine the necessary elastic constants to define the strain-energy density function for finite strain. Then, ab initio calculations-density functional theory-is used to calculate the nonlinear elastic response. Chapter 2 focuses on validating this methodology with atomic force microscope nanoindentation on molybdenum disulfide. Chapter 3 explores the convergence criteria of three density functional theory solvers to further verify the numerical calculations. Chapter 4 then uses this model to investigate

  15. Perovskite type nanopowders and thin films obtained by chemical methods

    Directory of Open Access Journals (Sweden)

    Viktor Fruth

    2010-09-01

    Full Text Available The review presents the contribution of the authors, to the preparation of two types of perovskites, namely BiFeO3 and LaCoO3, by innovative methods. The studied perovskites were obtained as powders, films and sintered bodies. Their complex structural and morphological characterization is also presented. The obtained results have underlined the important influence of the method of preparation on the properties of the synthesized perovskites.

  16. Magnetic properties of proton irradiated BiFeO3

    International Nuclear Information System (INIS)

    The crystal structure and magnetic properties of BiFeO3 samples, proton-irradiated with 0, 10, and 20 pC/μm2, were investigated with x-ray diffraction (XRD), vibrating sample magnetometer, and Mössbauer spectroscopy measurements. From the Rietveld refinement analysis of the XRD patterns, the crystal structure of BiFeO3 is determined to be rhombohedral with the space group of R3c. We have observed the decrease in the lattice constant and oxygen occupancy with proton irradiation. The magnetization hysteresis (M-H) curves show the appearance of the weak ferromagnetic behavior in the proton irradiated BiFeO3 samples. The Mössbauer spectra of proton irradiated BiFeO3 samples at 295 K were analyzed with two-sextets (B1 and B2) and doublet. From the isomer shift (δ) values, ionic states were determined to be Fe3+. Compared to non-irradiated sample, having the antiferromagnetic area ratio (two-sextets) of 45.47, 54.53% the antiferromagnetic and paramagnetic area ratios (doublet) of 10 and 20 pC/μm2 proton irradiated BiFeO3 samples are 41.36, 51.26, and 7.38% and 41.03, 50.90, and 8.07%, respectively. Our experimental observation suggests that the increase in the paramagnetic area ratio is due to the disappearance of superexchange interaction, resulted from the removal of the oxygen with proton irradiation. Also, the appearance of the weak ferromagnetic behavior is caused by the breaking of the antiferromagnetic coupling.

  17. Change in the magnetic structure of (Bi,SmFeO3 thin films at the morphotropic phase boundary probed by neutron diffraction

    Directory of Open Access Journals (Sweden)

    Shingo Maruyama

    2014-11-01

    Full Text Available We report on the evolution of the magnetic structure of BiFeO3 thin films grown on SrTiO3 substrates as a function of Sm doping. We determined the magnetic structure using neutron diffraction. We found that as Sm increases, the magnetic structure evolves from a cycloid to a G-type antiferromagnet at the morphotropic phase boundary, where there is a large piezoelectric response due to an electric-field induced structural transition. The occurrence of the magnetic structural transition at the morphotropic phase boundary offers another route towards room temperature multiferroic devices.

  18. Polycrystalline thin film photovoltaic technology

    Energy Technology Data Exchange (ETDEWEB)

    Ullal, H.S.; Zweibel, K.; Mitchell, R.L.; Noufi, R.

    1991-03-01

    Low-cost, high-efficiency thin-film modules are an exciting photovoltaic technology option for generating cost-effective electricity in 1995 and beyond. In this paper we review the significant technical progress made in the following thin films: copper indium diselenide, cadmium telluride, and polycrystalline thin silicon films. Also, the recent US DOE/SERI initiative to commercialize these emerging technologies is discussed. 6 refs., 9 figs.

  19. Resistance switching and memory effects in solution-processed BiFeO3/LaNiO3 junctions

    Science.gov (United States)

    Pandya, N. C.; Debnath, A. K.; Joshi, U. S.

    2016-02-01

    Resistance switching and memory effects have been observed in a heterostructure consisting of BiFeO3 (BFO) on a LaNiO3 (LNO) conducting oxide bottom electrode fabricated by chemical solution deposition on quartz substrates. The phase purity and lattice strain of monodispersed thin film nanostructures were confirmed by XRD. Bipolar switching with a resistance switching ratio of one order of magnitude at small bias voltages of  +1.3 V and  -0.7 V for positive and negative bias respectively has been estimated from the I-V traces measured over a span of more than 6 h. Excellent retention behavior of the BFO-LNO device is confirmed for its possible use as a non-volatile resistance random access memory device. The modeling of the I-V data suggests that in the low resistance state (on) Ohmic conduction is well fitted, whereas in the high resistance state (off) the trap-controlled space-charge-limited current mechanism dominates. The observed resistive switching (RS) is attributed to formation of a metallic filament and its rupture under electric stress conditions. The valence states of Fe ions in the fabricated device structures indicate that oxygen vacancies could also lead to RS in the device.

  20. Tunable electronic and magnetism of SrTiO3/BiFeO3 (001) superlattice: For electrochemical applications

    International Nuclear Information System (INIS)

    Practical strategy in tuning the conductivity and magnetism of SrTiO3/BiFeO3 (STO/BFO) (001) superlattice is investigated using the first-principles method based on density functional theory. Our calculated results show that both the conductivity and magnetism of this superlattice can be tuned via a control of its interface terminations. The STO layers maintain semiconducting, while the BFO layers demonstrate metallic character. Therefore, the conductivity of STO/BFO is controlled by the BFO layers. Furthermore, a magnetic STO/BFO (001) superlattice can be found in n-type TiO2/BiO interface but with heavy electron carriers. The thickness of BFO does not change the electronic structure and character of STO/BFO (001) superlattice. This study provides a fundamental understanding of the chemically turned conductivity and magnetism of BFO thin films, which may further advance electrochemical applications like magnetic-field aided chemical gas sensing, solar cells, and photo-catalytic chemical reactions

  1. Tunable electronic and magnetism of SrTiO3/BiFeO3 (001) superlattice: For electrochemical applications

    Science.gov (United States)

    Xu, Qiang; Sopiha, Kostiantyn; Sobhan, Mushtaq; Anariba, Franklin; Ong, Khuong Phuong; Zheng, Jian Wei; Wu, Ping

    2016-01-01

    Practical strategy in tuning the conductivity and magnetism of SrTiO3/BiFeO3 (STO/BFO) (001) superlattice is investigated using the first-principles method based on density functional theory. Our calculated results show that both the conductivity and magnetism of this superlattice can be tuned via a control of its interface terminations. The STO layers maintain semiconducting, while the BFO layers demonstrate metallic character. Therefore, the conductivity of STO/BFO is controlled by the BFO layers. Furthermore, a magnetic STO/BFO (001) superlattice can be found in n-type TiO2/BiO interface but with heavy electron carriers. The thickness of BFO does not change the electronic structure and character of STO/BFO (001) superlattice. This study provides a fundamental understanding of the chemically turned conductivity and magnetism of BFO thin films, which may further advance electrochemical applications like magnetic-field aided chemical gas sensing, solar cells, and photo-catalytic chemical reactions.

  2. Resistance switching and memory effects in solution-processed BiFeO3/LaNiO3 junctions

    International Nuclear Information System (INIS)

    Resistance switching and memory effects have been observed in a heterostructure consisting of BiFeO3 (BFO) on a LaNiO3 (LNO) conducting oxide bottom electrode fabricated by chemical solution deposition on quartz substrates. The phase purity and lattice strain of monodispersed thin film nanostructures were confirmed by XRD. Bipolar switching with a resistance switching ratio of one order of magnitude at small bias voltages of  +1.3 V and  −0.7 V for positive and negative bias respectively has been estimated from the I–V traces measured over a span of more than 6 h. Excellent retention behavior of the BFO–LNO device is confirmed for its possible use as a non-volatile resistance random access memory device. The modeling of the I–V data suggests that in the low resistance state (on) Ohmic conduction is well fitted, whereas in the high resistance state (off) the trap-controlled space-charge-limited current mechanism dominates. The observed resistive switching (RS) is attributed to formation of a metallic filament and its rupture under electric stress conditions. The valence states of Fe ions in the fabricated device structures indicate that oxygen vacancies could also lead to RS in the device. (paper)

  3. Investigation on Silicon Thin Film Solar Cells

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The preparation, current status and trends are investigated for silicon thin film solar cells. The advantages and disadvantages of amorphous silicon thin film, polycrystalline silicon thin film and mono-crystalline silicon thin film solar cells are compared. The future development trends are pointed out. It is found that polycrystalline silicon thin film solar cells will be more promising for application with great potential.

  4. Photoinduced magnetoresistance and magnetic-field-modulated photoelectric response in BiFeO3/Si heterojunctions

    Science.gov (United States)

    Xi, Jianfeng; Ni, Hao; Zhao, Kun; Lu, Huibin; Guo, Erjia; He, Meng; Jin, Kuijuan; Zhou, Yueliang; Yang, Guozhen; Xiao, Lizhi; Zhang, Zhenwei

    2016-05-01

    The BiFeO3 film grown on Si substrate without template exhibits a diode-like effect, and the forward direction of the diode can be switched by external electric fields. The laser irradiation and the magnetic field can induce polarization, thus modulating the photovoltaic effect. The magnetoresistance values change from -1.19 to -5.79 and to -35.48 % dramatically under 50 μA current in 770 Oe when the junction is irradiated by 532 and 1064 nm lasers, respectively. These results reveal unusual and interesting charge conduction behavior in leaky ferroelectrics and should promote the study of BiFeO3 based on multifunctional materials.

  5. Structural study of yttrium substituted BiFeO3

    Science.gov (United States)

    Mejía Gómez, J. A.; Canaria, C.; Ochoa Burgos, R.; Ortiz, C. A.; Supelano, G. I.; Parra Vargas, C. A.

    2016-02-01

    Yttrium-substituted Bi1-xYxFeO3 (x=0, 0.03, 0.07, 0.15, 0.2 and 0.5) samples were prepared by solid state reaction technique. Morphological analysis was obtained by Scanning Electron Microscopy (SEM) technique indicating mainly granular behaviour. In addition, the substitution of yttrium promotes smaller particle size of BiFeO3. The obtained samples were also studied by X-ray diffraction (XRD). The crystal structure and the lattice parameters were confirmed by XRD. Rietveld refinement of experimental X-ray diffraction patterns showed that substituted BiFeO3 compounds crystallize in a R3c type structure and the lattice parameters decrease as Y concentration increases.

  6. The Ultrathin Limit and Dead-layer Effects in Local Polarization Switching of BiFeO3

    Energy Technology Data Exchange (ETDEWEB)

    Maksymovych, Petro [ORNL; Huijben, Mark [University of Twente, Netherlands; Pan, Minghu [ORNL; Jesse, Stephen [ORNL; Balke, Nina [ORNL; Chang, Hye Jung [ORNL; Borisevich, Albina Y [ORNL; Baddorf, Arthur P [ORNL; Rijnders, Guus [MESA+ University of Twente, Enschede, Netherlands; Blank, Dave H. A. [University of Twente, Netherlands; Ramesh, R. [University of California, Berkeley; Kalinin, Sergei V [ORNL

    2012-01-01

    Using piezoresponse force microscopy in ultra-high vacuum, polarization switching has been detected and quantified in epitaxial BiFeO3 films from 200 down to ~ 4 unit cells. Local remnant piezoresponse was used to infer the applied electric field inside the ferroelectric volume, and account for the elusive effect of dead-layers in ultrathin films. The dead-layer manifested itself in the slower than anticipated decrease of the switching bias with film thickness, yielding apparent Kay-Dunn scaling of the switching field, while the statistical analysis of hysteresis loops revealed lateral variation of the dead-layer with sub-10 nm resolution.

  7. Polyimide Aerogel Thin Films

    Science.gov (United States)

    Meador, Mary Ann; Guo, Haiquan

    2012-01-01

    Polyimide aerogels have been crosslinked through multifunctional amines. This invention builds on "Polyimide Aerogels With Three-Dimensional Cross-Linked Structure," and may be considered as a continuation of that invention, which results in a polyimide aerogel with a flexible, formable form. Gels formed from polyamic acid solutions, end-capped with anhydrides, and cross-linked with the multifunctional amines, are chemically imidized and dried using supercritical CO2 extraction to give aerogels having density around 0.1 to 0.3 g/cubic cm. The aerogels are 80 to 95% porous, and have high surface areas (200 to 600 sq m/g) and low thermal conductivity (as low as 14 mW/m-K at room temperature). Notably, the cross-linked polyimide aerogels have higher modulus than polymer-reinforced silica aerogels of similar density, and can be fabricated as both monoliths and thin films.

  8. Polycrystalline thin films

    Science.gov (United States)

    Zweibel, K.; Mitchell, R.; Ullal, H.

    1987-02-01

    This annual report for fiscal year 1986 summarizes the status, accomplishments, and projected future research directions of the Polycrystalline Thin Film Task in the Photovoltaic Program Branch of the Solar Energy Research Institute's Solar Electric Research Division. Subcontracted work in this area has concentrated on the development of CuInSe2 and CdTe technologies. During FY 1986, major progress was achieved by subcontractors in (1) achieving 10.5% (SERI-verified) efficiency with CdTe, (2) improving the efficiency of selenized CuInSe2 solar cells to nearly 8%, and (3) developing a transparent contact to CdTe cells for potential use in the top cells of tandem structures.

  9. Thin-film microextraction.

    Science.gov (United States)

    Bruheim, Inge; Liu, Xiaochuan; Pawliszyn, Janusz

    2003-02-15

    The properties of a thin sheet of poly(dimethylsiloxane) (PDMS) membrane as an extraction phase were examined and compared to solid-phase microextraction (SPME) PDMS-coated fiber for application to semivolatile analytes in direct and headspace modes. This new PDMS extraction approach showed much higher extraction rates because of the larger surface area to extraction-phase volume ratio of the thin film. Unlike the coated rod formats of SPME using thick coatings, the high extraction rate of the membrane SPME technique allows larger amounts of analytes to be extracted within a short period of time. Therefore, higher extraction efficiency and sensitivity can be achieved without sacrificing analysis time. In direct membrane SPME extraction, a linear relationship was found between the initial rate of extraction and the surface area of the extraction phase. However, for headspace extraction, the rates were somewhat lower because of the resistance to analyte transport at the sample matrix/headspace barrier. It was found that the effect of this barrier could be reduced by increasing either agitation, temperature, or surface area of the sample matrix/headspace interface. A method for the determination of PAHs in spiked lake water samples was developed based on the membrane PDMS extraction coupled with GC/MS. A linearity of 0.9960 and detection limits in the low-ppt level were found. The reproducibility was found to vary from 2.8% to 10.7%. PMID:12622398

  10. Origin of the giant linear magnetoelectric effect in perovskitelike multiferroic BiFeO3

    Science.gov (United States)

    Popkov, A. F.; Davydova, M. D.; Zvezdin, K. A.; Solov'yov, S. V.; Zvezdin, A. K.

    2016-03-01

    In this article the mechanism of the linear magnetoelectric (ME) effect in the rhombohedral multiferroic BiFeO3 is considered. The study is based on the symmetry approach of the Ginzburg-Landau type, in which polarization, antiferrodistortion, and antiferromagnetic momentum vectors are viewed as ordering parameters. We demonstrate that the linear ME effect in BFO is caused by reorientation of the antiferrodistortion vector in either electric or magnetic field. The numerical estimations, which show quantitative agreement with the results of the recent measurements in film samples, have been performed. A possibility of significant enhancement of the magnetoelectric effect by applying an external static electric field has been investigated. The considered approach is promising for explaining the high values of the ME effect in composite films and heterostructures with BFO.

  11. Thin functional conducting polymer films

    OpenAIRE

    Tian, S.

    2005-01-01

    In the present study, thin functional conducting polyaniline (PANI) films, either doped or undoped, patterned or unpatterned, were prepared by different approaches. The properties of the obtained PANI films were investigated in detail by a combination of electrochemistry with several other techniques, such as SPR, QCM, SPFS, diffraction, etc. The sensing applications (especially biosensing applications) of the prepared PANI films were explored. Firstly, the pure PANI films were prepar...

  12. Interfaces and thin films physics

    International Nuclear Information System (INIS)

    The 1988 progress report of the Interfaces and Thin Film Physics laboratory (Polytechnic School France) is presented. The research program is focused on the thin films and on the interfaces of the amorphous semiconductor materials: silicon and silicon germanium, silicon-carbon and silicon-nitrogen alloys. In particular, the following topics are discussed: the basic processes and the kinetics of the reactive gas deposition, the amorphous materials manufacturing, the physico-chemical characterization of thin films and interfaces and the electron transport in amorphous semiconductors. The construction and optimization of experimental devices, as well as the activities concerning instrumentation, are also described

  13. Stress induced enhanced polarization in multilayer BiFeO3/BaTiO3 structure with improved energy storage properties

    Directory of Open Access Journals (Sweden)

    Savita Sharma

    2015-10-01

    Full Text Available Present work reports the fabrication of a multilayer (5-layer structure of BiFeO3(BFO/BaTiO3(BTO using spin-coating technique. The crystallographic structure, surface morphology and ferroelectric behavior of multilayer structure in metal-ferroelectric-metal capacitor have been studied. Le-Bail refinement of X-ray diffraction data revealed the formation of polycrystalline pure perovskite phase with induced stress. The values of remnant (Pr and saturation polarization (Ps for BFO/BTO multilayer structure are found to be 38.14 μC/cm2 and 71.54 μC/cm2 respectively, which are much higher than the corresponding values reported for bare BFO thin film. A large value of dielectric constant of 187 has been obtained for multilayer structure with a low leakage current density of 1.09 × 10−7 A/cm2 at applied bias of 10 V. The BFO/BTO multilayer structure favors the enhanced energy storage capacity as compared to bare BFO thin film with improved values of energy-density and charge-discharge efficiency as 121 mJ/cm3 and 59% respectively, suggesting futuristic energy storage applications.

  14. Stress induced enhanced polarization in multilayer BiFeO3/BaTiO3 structure with improved energy storage properties

    International Nuclear Information System (INIS)

    Present work reports the fabrication of a multilayer (5-layer) structure of BiFeO3(BFO)/BaTiO3(BTO) using spin-coating technique. The crystallographic structure, surface morphology and ferroelectric behavior of multilayer structure in metal-ferroelectric-metal capacitor have been studied. Le-Bail refinement of X-ray diffraction data revealed the formation of polycrystalline pure perovskite phase with induced stress. The values of remnant (Pr) and saturation polarization (Ps) for BFO/BTO multilayer structure are found to be 38.14 μC/cm2 and 71.54 μC/cm2 respectively, which are much higher than the corresponding values reported for bare BFO thin film. A large value of dielectric constant of 187 has been obtained for multilayer structure with a low leakage current density of 1.09 × 10−7 A/cm2 at applied bias of 10 V. The BFO/BTO multilayer structure favors the enhanced energy storage capacity as compared to bare BFO thin film with improved values of energy-density and charge-discharge efficiency as 121 mJ/cm3 and 59% respectively, suggesting futuristic energy storage applications

  15. Thin-film solar cell

    NARCIS (Netherlands)

    Metselaar, J.W.; Kuznetsov, V.I.

    1998-01-01

    The invention relates to a thin-film solar cell provided with at least one p-i-n junction comprising at least one p-i junction which is at an angle alpha with that surface of the thin-film solar cell which collects light during operation and at least one i-n junction which is at an angle beta with t

  16. A strain-driven morphotropic phase boundary in BiFeO3.

    Science.gov (United States)

    Zeches, R J; Rossell, M D; Zhang, J X; Hatt, A J; He, Q; Yang, C-H; Kumar, A; Wang, C H; Melville, A; Adamo, C; Sheng, G; Chu, Y-H; Ihlefeld, J F; Erni, R; Ederer, C; Gopalan, V; Chen, L Q; Schlom, D G; Spaldin, N A; Martin, L W; Ramesh, R

    2009-11-13

    Piezoelectric materials, which convert mechanical to electrical energy and vice versa, are typically characterized by the intimate coexistence of two phases across a morphotropic phase boundary. Electrically switching one to the other yields large electromechanical coupling coefficients. Driven by global environmental concerns, there is currently a strong push to discover practical lead-free piezoelectrics for device engineering. Using a combination of epitaxial growth techniques in conjunction with theoretical approaches, we show the formation of a morphotropic phase boundary through epitaxial constraint in lead-free piezoelectric bismuth ferrite (BiFeO3) films. Electric field-dependent studies show that a tetragonal-like phase can be reversibly converted into a rhombohedral-like phase, accompanied by measurable displacements of the surface, making this new lead-free system of interest for probe-based data storage and actuator applications. PMID:19965507

  17. Thin-Film Power Transformers

    Science.gov (United States)

    Katti, Romney R.

    1995-01-01

    Transformer core made of thin layers of insulating material interspersed with thin layers of ferromagnetic material. Flux-linking conductors made of thinner nonferromagnetic-conductor/insulator multilayers wrapped around core. Transformers have geometric features finer than those of transformers made in customary way by machining and mechanical pressing. In addition, some thin-film materials exhibit magnetic-flux-carrying capabilities superior to those of customary bulk transformer materials. Suitable for low-cost, high-yield mass production.

  18. Dielectric investigations of BiFeO3 ceramics

    Directory of Open Access Journals (Sweden)

    Simonas Greičius

    2009-06-01

    Full Text Available In this paper we present the results from the investigation of the dielectric permittivity of BiFeO3 ceramics, prepared by mechanochemical synthesis method in a broad frequency and temperature range. The dielectric permittivity is mainly caused by high conductivity, which is suppressed in the frequencies above 1 MHz. The investigated ceramics showed conductivity activation energy E/k=11280±12 K, and σ0=54161±800 S. The plots of M* revealed conductivity mechanism with τ0=1.12·10^-13 s, and E/k=9245 K.

  19. Size effects in thin films

    CERN Document Server

    Tellier, CR; Siddall, G

    1982-01-01

    A complete and comprehensive study of transport phenomena in thin continuous metal films, this book reviews work carried out on external-surface and grain-boundary electron scattering and proposes new theoretical equations for transport properties of these films. It presents a complete theoretical view of the field, and considers imperfection and impurity effects.

  20. Nanotemplated lead telluride thin films

    OpenAIRE

    Li, Xiaohong; Nandhakumar, Iris S.; Attard, George S.; Markham, Matthew L.; Smith, David C.; Baumberg, Jeremy J.

    2009-01-01

    Direct lyotropic liquid crystalline templating has been successfully applied to produce nanostructured IV–VI semiconductor PbTe thin films by electrodeposition both on gold and n-type (100) silicon substrates. The PbTe films were characterized by transmission electron microscopy, X-ray diffraction and polarized optical microscopy and the results show that the films have a regular hexagonal nanoarchitecture with a high crystalline rock salt structure and exhibit strong birefringenc...

  1. Thin films and froth flotation

    International Nuclear Information System (INIS)

    The properties of thin, aqueous films on solid surfaces and their central role in the froth flotation process are discussed. The stability of these films can generally be described in terms of electrostatic and van der Waals forces. Significant experimental and theoretical advances are required in many areas (e.g. short range forces, film drainage) before a clear picture of the collision of, adhesion between and detachment of bubbles and particles will emerge. (orig.)

  2. Thin-film ternary superconductors

    International Nuclear Information System (INIS)

    Physical properties and preparation methods of thin film ternary superconductors, (mainly molybdenum chalcogenides) are reviewed. Properties discussed include the superconducting critical fields and critical currents, resistivity and the Hall effect. Experimental results at low temperatures, together with electron microscopy data are used to determine magnetic flux pinning mechanisms in films. Flux pinning results, together with an empirical model for pinning, are used to get estimates for possible applications of thin film ternary superconductors where high current densities are needed in the presence of high magnetic fields. The normal state experimental data is used to derive several Fermi surface parameters, e.g. the Fermi velocity and the effective Fermi surface area. (orig.)

  3. Calorimetry of epitaxial thin films.

    Science.gov (United States)

    Cooke, David W; Hellman, F; Groves, J R; Clemens, B M; Moyerman, S; Fullerton, E E

    2011-02-01

    Thin film growth allows for the manipulation of material on the nanoscale, making possible the creation of metastable phases not seen in the bulk. Heat capacity provides a direct way of measuring thermodynamic properties of these new materials, but traditional bulk calorimetric techniques are inappropriate for such a small amount of material. Microcalorimetry and nanocalorimetry techniques exist for the measurements of thin films but rely on an amorphous membrane platform, limiting the types of films which can be measured. In the current work, ion-beam-assisted deposition is used to provide a biaxially oriented MgO template on a suspended membrane microcalorimeter in order to measure the specific heat of epitaxial thin films. Synchrotron x-ray diffraction showed the biaxial order of the MgO template. X-ray diffraction was also used to prove the high quality of epitaxy of a film grown onto this MgO template. The contribution of the MgO layer to the total heat capacity was measured to be just 6.5% of the total addenda contribution. The heat capacity of a Fe(.49)Rh(.51) film grown epitaxially onto the device was measured, comparing favorably to literature data on bulk crystals. This shows the viability of the MgO∕SiN(x)-membrane-based microcalorimeter as a way of measuring the thermodynamic properties of epitaxial thin films. PMID:21361612

  4. Mecanosíntese do composto BiFeO3 Mechanosynthesis of the BiFeO3 compound

    Directory of Open Access Journals (Sweden)

    V. F. Freitas

    2008-09-01

    Full Text Available Os compostos cerâmicos BiFeO3 puro e modificado (Bi0,95R0,05FeO3, com terras raras R = Gd ou Eu, foram sintetizados por moagem em altas energias. As amostras foram analisadas por difração de raios X, microscopia eletrônica de varredura e espectroscopia por energia dispersiva de raios X. A difração de raios X indicou que as amostras modificadas com Eu são monofásicas, enquanto que as amostras puras e modificadas com Gd apresentaram majoritariamente a fase BiFeO3, com uma pequena quantidade de outras fases. A espectroscopia por energia dispersiva de raios X revelou a presença dos átomos modificantes na amostra e o mapeamento destes átomos indicou uma distribuição homogênea deles em toda a amostra. A microscopia eletrônica de varredura mostrou uma significante diminuição no tamanho das partículas, estando estas com dimensões sub-micrométricas e com diâmetro médio em torno de 500 nm. Estudos de densificação dos corpos cerâmicos indicaram compostos altamente densos, com densidades relativas acima de 0,9 sendo que o composto modificado com Eu alcançou a densidade relativa ρ/ρ0 = 0,98.The, pure and rare earth modified (Bi0.95R0.05FeO3 / R = Gd or Eu BiFeO3 compounds were synthesized by high-energy ball milling. The samples were analyzed by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The X-ray diffraction results indicated single phase Eu modified samples, while the pure and Gd modified ones presented the BiFeO3 as majority phase, and small amount of the spurious phase. The energy dispersive spectroscopy revealed the presence of the modifiers atoms in the sample and the mapping of these atoms indicated the homogeneous distribution of them in the whole samples. The scanning electron microscopy showed a decrease significant on the particle size, with medium diameter around 500 nm. Densification studies indicated high-dense ceramics body, with relative density above of 0.9, were Eu modified compound reached relative density ρ/ρ0 = 0.98.

  5. Large pyramid shaped single crystals of BiFeO3 by solvothermal synthesis method

    International Nuclear Information System (INIS)

    Synthesis parameters are optimized in order to grow single crystals of multiferroic BiFeO3. 2 to 3 mm size pyramid (tetrahedron) shaped single crystals were successfully obtained by solvothermal method. Scanning electron microscopy with EDAX confirmed the phase formation. Raman scattering spectra of bulk BiFeO3 single crystals have been measured which match well with reported spectra.

  6. Double-perovskite multiferroic Bi2FeCrO6 polycrystalline thin film: The structural, multiferroic, and ferroelectric domain properties

    International Nuclear Information System (INIS)

    Highlights: ► Double perovskite multiferroic BFCO film was grown by PLD method. ► Domain evolution under external electric field was simulated by Monte-Carlo method. ► Better electrical, ferroelectric and magnetic properties were found in BFCO film. ► BFCO film may be a promising material for functional device application. -- Abstract: Double-perovskite Bi2FeCrO6 (BFCO) thin film has been deposited on Pt/Ti/SiO2/Si (1 0 0) substrate by pulsed laser deposition method. X-ray diffraction reveals that the BFCO film was polycrystalline and high purity. The surface morphology in BFCO film exhibits the dense and uniform grain. Interestingly, compared with BiFeO3 film, the BFCO film shows a better ferroelectric properties. Moreover, a well-defined magnetic hysteresis of the BFCO film indicates a ferromagnetic property at room temperature. The ferroelectric domain structure of polycrystalline BFCO film was investigated by piezoresponse force microscopy. Furthermore, the domain structure of polycrystalline BFCO film under an applied electric field was simulated by a Monte Carlo method. Those results suggest that the multiferroic BFCO double-perovskite thin film may be a promising functional material for the future device application

  7. Nanoscale mechanical softening of morphotropic BiFeO3.

    Science.gov (United States)

    Heo, Yooun; Jang, Byong-Kweon; Kim, Seung Jin; Yang, Chan-Ho; Seidel, Jan

    2014-12-01

    Mechanical switching can be used to form phase-transformed areas in mixed-phase bismuth ferrite thin films, which might be exploited to yield various soft elastic areas with greatly reduced Young's modulus on the nanoscale. Due to the mechanically susceptible nature of morphotropic phase boundaries in multiferroics, combined elastic control of electronic, magnetic, and ferroelectric properties becomes possible. PMID:25327302

  8. Bismuth ferrite based thin films, nanofibers, and field effect transistor devices

    Science.gov (United States)

    Rivera-Beltran, Rut

    In this research an attempt has been made to explore bismuth ferrite thin films with low leakage current and nanofibers with high photoconductivity. Thin films were deposited with pulsed laser deposition (PLD) method. An attempt has been made to develop thin films under different deposition parameters with following target compositions: i) 0.6BiFeO3-0.4(Bi0.5 K0.5)TiO3 (BFO-BKT) and ii) bi-layered 0.88Bi 0.5Na0.5TiO3-0.08Bi0.5K0.5TiO 3-0.04BaTiO3/BiFeO3 (BNT-BKT-BT/BFO). BFO-BKT thin film shows suppressed leakage current by about four orders of magnitude which in turn improve the ferroelectric and dielectric properties of the films. The optimum remnant polarization is 19 muC.cm-2 at the oxygen partial pressure of 300 mtorr. The BNT-BKT-BT/BFO bi-layered thin films exhibited ferroelectric behavior as: Pr = 22.0 muC.cm-2, Ec = 100 kV.cm-1 and epsilonr = 140. The leakage current of bi-layered thin films have been reduced two orders of magnitude compare to un-doped bismuth ferrite. Bismuth ferrite nanofibers were developed by electrospinning technique and its electronic properties such as photoconductivity and field effect transistor performance were investigated extensively. Nanofibers were deposited by electrospinning of sol-gel solution on SiO2/Si substrate at driving voltage of 10 kV followed by heat treatment at 550 °C for 2 hours. The composition analysis through energy dispersive detector and electron energy loss spectroscopy revealed the heterogeneous nature of the composition with Bi rich and Fe deficient regions. X-ray photoelectron spectroscopy results confirmed the combination of Fe3+ and Fe2+ valence state in the fibers. The photoresponse result is almost hundred times higher for a fiber of 40 nm diameter compared to a fiber with 100 nm diameter. This effect is described by a size dependent surface recombination mechanism. A single and multiple BFO nanofibers field effect transistors devices were fabricated and characterized. Bismuth ferrite FET behaves

  9. Semiconductor-nanocrystal/conjugated polymer thin films

    Science.gov (United States)

    Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

    2010-08-17

    The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

  10. The magnetism of BiFeO3 powders

    Science.gov (United States)

    Luo, Xi; Tseng, Li-Ting; Li, Sean; Yi, Jiabao

    2015-12-01

    Conventional sintering and direct ball milling of Bi2O3 + Fe2O3 mixture were used for the fabrication of BiFeO3 powders. The fabricated powders were performed annealing or high energy ball milling to vary the grain size from bottom-up or top-down. It was found that the magnetization of the powders synthesized by both methods plotted with the reciprocal of the grain size could be linearly fitted, indicating that the magnetism is from the finite size effect. Exchange bias phenomenon was observed after field cooling (FC) of the powders, confirming the magnetization is due to the uncompensated or canted surface spins. No spin glass behavior was found in these powders.

  11. Preparation of thin vyns films

    International Nuclear Information System (INIS)

    The fabrication of thin films of VYNS resin (copolymer of chloride and vinyl acetate) of superficial density from 3 to 50 μg/cm2 with solutions in cyclohexanone is presented. Study and discussion of some properties compared with formvar film (polyvinyl formals). It appears that both can be used as source supports but formvar films are prepared more easily and more quickly, in addition they withstand higher temperatures. The main quality of VYNS is that they can be easily separated even several days after their preparation

  12. Phase coexistence, phase transitions, and piezoelectric switching in highly-strained BiFeO3

    Science.gov (United States)

    Christen, Hans M.; Beekman, C.; Siemons, W.; Chi, M.; Howe, J. Y.; Biegalski, M. D.; Balke, N.; Maksymovych, P.; Ward, T. Z.; Farrar, A. K.; Romero, J. B.; Tenne, D.

    2013-03-01

    Highly strained (T') BiFeO3 films are investigated as function of temperature by x-ray diffraction in combination with atomic-force, piezo-response force, and transmission electron microscopies. In these films on LaAlO3 substrates, the coexistence of the T' majority phase (c/a ~ 1.25) with an intermediary S' polymorph (c/a ~ 1.09) leads to the formation of stripe patterns in samples where the bulk-like, nearly rhombohedral R' polymorph is absent. While T' films at 300K are monoclinic, our results reveal a true tetragonal high-temperature phase (at T >=700K) for which Raman spectroscopy demonstrates a polar nature. However, piezoelectric switching of the T' phase is possible only in the presence of the S' polymorph. This polymorph, and the stripe patterns that result from its coexistence with the T' form appear after growth upon cooling below ~570K. This shows that the S' polymorph is formed by additional stress resulting from the differences in thermal expansion between film and substrate. These results point to new approaches for tuning functional properties in materials exhibiting strain-induced polymorphic phase transitions. Sponsored by US-DOE, BES, MSED and supported at ORNL's CNMS and ShaRE user programs by US-DOE, BES. Raman studies supported by NSF grant DMR-1006136.

  13. Giant dielectric response and enhanced thermal stability of multiferroic BiFeO3

    International Nuclear Information System (INIS)

    Highlights: • We report a novel wet chemical route for facile and large-scale fabricate of BiFeO3. • Giant dielectric response was observed in BiFeO3 ceramics. • BiFeO3 nanoparticles, fabricated by the novel method, are thermally stable up to 900 °C. • This synthesis technique can be easily extended to many other functional material systems. - Abstract: A wet chemical synthesis technique for large-scale fabrication of multiferroic bismuth ferrite (BiFeO3) nanoparticles under ambient pressure is reported. The process employs bismuth nitride and potassium hexacyanoferrate as raw materials and involves easy control and simple operation steps. The single crystalline nature of BiFeO3 was confirmed by X-ray diffraction (XRD) and selected area electron diffraction pattern. This synthesis technique can be extended to many other material systems and it provides a general, simple and convenient route for large-scale fabrication of nanocomplex oxides. Our results revealed that the synthesized BiFeO3 ceramics exhibited giant dielectric constant (>104) and two dielectric relaxations. A Debye-like relaxation was found at relatively low temperature with activation energy of 0.25 eV, which was assigned to the carrier hopping process between Fe2+ and Fe3+ sites in BiFeO3. The grain boundary effect contributed to the relative high temperature dielectric relaxation

  14. Shielding superconductors with thin films

    CERN Document Server

    Posen, Sam; Catelani, Gianluigi; Liepe, Matthias U; Sethna, James P

    2015-01-01

    Determining the optimal arrangement of superconducting layers to withstand large amplitude AC magnetic fields is important for certain applications such as superconducting radiofrequency cavities. In this paper, we evaluate the shielding potential of the superconducting film/insulating film/superconductor (SIS') structure, a configuration that could provide benefits in screening large AC magnetic fields. After establishing that for high frequency magnetic fields, flux penetration must be avoided, the superheating field of the structure is calculated in the London limit both numerically and, for thin films, analytically. For intermediate film thicknesses and realistic material parameters we also solve numerically the Ginzburg-Landau equations. It is shown that a small enhancement of the superheating field is possible, on the order of a few percent, for the SIS' structure relative to a bulk superconductor of the film material, if the materials and thicknesses are chosen appropriately.

  15. Thin Film Solid Lubricant Development

    Science.gov (United States)

    Benoy, Patricia A.

    1997-01-01

    Tribological coatings for high temperature sliding applications are addressed. A sputter-deposited bilayer coating of gold and chromium is investigated as a potential solid lubricant for protection of alumina substrates during sliding at high temperature. Evaluation of the tribological properties of alumina pins sliding against thin sputtered gold films on alumina substrates is presented.

  16. Thin film polymeric gel electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Derzon, Dora K. (1554 Rosalba St. NE., Albuquerque, Bernalillo County, NM 87112); Arnold, Jr., Charles (3436 Tahoe, NE., Albuquerque, Bernalillo County, NM 87111); Delnick, Frank M. (9700 Fleming Rd., Dexter, MI 48130)

    1996-01-01

    Novel hybrid thin film electrolyte, based on an organonitrile solvent system, which are compositionally stable, environmentally safe, can be produced efficiently in large quantity and which, because of their high conductivities .apprxeq.10.sup.-3 .OMEGA..sup.-1 cm.sup.-1 are useful as electrolytes for rechargeable lithium batteries.

  17. Optical thin films test methodology

    International Nuclear Information System (INIS)

    An over view of different test procedures for thin film optical coatings have been discussed in this paper. These procedures cover optical coatings for high precision and commercial applications. These tests include visual inspection test, self adhesion test, moderate abrasion test, etc. Two groups of testing sequences have been given depending upon the environmental conditions. (author)

  18. Superfast Thinning of a Nanoscale Thin Liquid Film

    OpenAIRE

    Winkler, Michael; Kofod, Guggi; Krastev, Rumen; Abel, Markus

    2011-01-01

    This fluid dynamics video demonstrates an experiment on superfast thinning of a freestanding thin aqueous film. The production of such films is of fundamental interest for interfacial sciences and the applications in nanoscience. The stable phase of the film is of the order $5-50\\,nm$; nevertheless thermal convection can be established which changes qualitatively the thinning behavior from linear to exponentially fast. The film is thermally driven on one spot by a very cold needle, establishi...

  19. Enhanced dielectric properties of multilayered BiFeO3/BaTiO3 capacitors deposited by pulsed laser deposition

    Science.gov (United States)

    Sharma, Savita; Tomar, Monika; Puri, Nitin K.; Gupta, Vinay

    2016-04-01

    We report on dielectric studies of BiFeO3(BFO)/BaTiO3(BTO) multilayer structure fabricated by pulsed laser deposition technique. Multilayered capacitors were prepared by increasing number of alternating individual layers from 2 to 7 while maintaining the total thickness of the layered structure as 350 nm. The dielectric constant of the BFO/BTO multilayer structure was significantly increased to 772 (at 1 kHz) and the dielectric loss decreased to 1.08 (at 1 kHz) in comparison to that of bare BFO and BTO thin films of 350 nm thickness. Further the dielectric constant increased with increasing number of individual layers. The increase in dielectric constant is related to the enhancement of ferroelectricity and reduced leakage current which is due to the induced stress at the interface of BFO and BTO layer in the multilayer capacitor. A high value of ferroelectric polarization (˜ 99.80 µC/cm2) was obtained for 6-layer BFO/BTO structure. The multilayer structure exhibited superior dielectric properties and can be undeniably used as the dielectric layer in silicon-based capacitors and tunable microwave device applications.

  20. Phase Coarsening in Thin Films

    Science.gov (United States)

    Wang, K. G.; Glicksman, M. E.

    2015-08-01

    Phase coarsening (Ostwald ripening) phenomena are ubiquitous in materials growth processes such as thin film formation. The classical theory explaining late-stage phase coarsening phenomena was developed by Lifshitz and Slyozov, and by Wagner in the 1960s. Their theory is valid only for a vanishing volume fraction of the second phase in three dimensions. However, phase coarsening in two-dimensional systems is qualitatively different from that in three dimensions. In this paper, the many-body concept of screening length is reviewed, from which we derive the growth law for a `screened' phase island, and develop diffusion screening theory for phase coarsening in thin films. The coarsening rate constant, maximum size of phase islands in films, and their size distribution function will be derived from diffusion screening theory. A critical comparison will be provided of prior coarsening concepts and improvements derived from screening approaches.

  1. Polarization Manipulation via Orientation Control in Polycrystalline BiFeO3 Thin Films on Biaxially Textured, Flexible Metallic Tapes

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Junsoo [ORNL; Goyal, Amit [ORNL; Jesse, Stephen [ORNL; Heatherly Jr, Lee [ORNL

    2011-01-01

    (111)-, (101)-, and (001)-oriented polycrystalline BiFeO3 films were fabricated on rolling-assisted biaxially textured substrates (RABiTS) with appropriate, buffer layer engineering of heteroepitaxially grown buffer multilayers on RABiTS. The crystallographic orientation and polarization direction were confirmed using X-ray diffraction and piezoresponse force microscopy (PFM), respectively. All the films exhibited excellent ferroelectric properties. Switching spectroscopy PFM demonstrated that the switching polarization in (111)-oriented polycrystalline BiFeO3 films is higher than (101) or (001) oriented films. These high-quality, BiFeO3 films on low-cost, flexible, biaxially textured metallic tapes with controllable orientation and polarization are attractive for application in flexible ferroelectric devices.

  2. Thin films stress modeling : a novel approach

    OpenAIRE

    Bhattacharyya, A. S.; Ramgiri, Praveen Kumar

    2015-01-01

    A novel approach to estimate the thin film stress was discussed based on surface tension. The effect of temperature and film thickness was studies. The effect of stress on the film mechanical properties was observed.

  3. Correlation of magnetoelectric coupling in multiferroic BaTiO3-BiFeO3 superlattices with oxygen vacancies and antiphase octahedral rotations

    International Nuclear Information System (INIS)

    Multiferroic (BaTiO3-BiFeO3) × 15 multilayer heterostructures show high magnetoelectric (ME) coefficients αME up to 24 V/cm·Oe at 300 K. This value is much higher than that of a single-phase BiFeO3 reference film (αME = 4.2 V/cm·Oe). We found clear correlation of ME coefficients with increasing oxygen partial pressure during growth. ME coupling is highest for lower density of oxygen vacancy-related defects. Detailed scanning transmission electron microscopy and selected area electron diffraction microstructural investigations at 300 K revealed antiphase rotations of the oxygen octahedra in the BaTiO3 single layers, which are an additional correlated defect structure of the multilayers

  4. Selective inorganic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, M.L.F.; Pohl, P.I.; Brinker, C.J. [Sandia National Labs., Albuquerque, NM (United States)

    1997-04-01

    Separating light gases using membranes is a technology area for which there exists opportunities for significant energy savings. Examples of industrial needs for gas separation include hydrogen recovery, natural gas purification, and dehydration. A membrane capable of separating H{sub 2} from other gases at high temperatures could recover hydrogen from refinery waste streams, and facilitate catalytic dehydrogenation and the water gas shift (CO + H{sub 2}O {yields} H{sub 2} + CO{sub 2}) reaction. Natural gas purification requires separating CH{sub 4} from mixtures with CO{sub 2}, H{sub 2}S, H{sub 2}O, and higher alkanes. A dehydrating membrane would remove water vapor from gas streams in which water is a byproduct or a contaminant, such as refrigeration systems. Molecular sieve films offer the possibility of performing separations involving hydrogen, natural gas constituents, and water vapor at elevated temperatures with very high separation factors. It is in applications such as these that the authors expect inorganic molecular sieve membranes to compete most effectively with current gas separation technologies. Cryogenic separations are very energy intensive. Polymer membranes do not have the thermal stability appropriate for high temperature hydrogen recovery, and tend to swell in the presence of hydrocarbon natural gas constituents. The authors goal is to develop a family of microporous oxide films that offer permeability and selectivity exceeding those of polymer membranes, allowing gas membranes to compete with cryogenic and adsorption technologies for large-scale gas separation applications.

  5. Ab Initio Study of BiFeO3: Thermodynamic Stability Conditions.

    Science.gov (United States)

    Heifets, E; Kotomin, E A; Bagaturyants, A A; Maier, J

    2015-07-16

    BiFeO3 is investigated intensively, mainly as a multiferroic material. In this paper, the state-of-the-art ab initio hybrid functional approach with atomic basis sets was employed for a study of the stability range of BiFeO3 with respect to its decomposition into binary oxides and elementary metals, as a function of temperature and oxygen partial pressure. The calculated atomic and electronic structure of BiFeO3 was compared with previous LDA+U calculations using plane-wave basis sets. Based on performed calculations, the phase diagram was constructed, which allows us to predict the stability region of stoichiometric BiFeO3. PMID:26266871

  6. Interfacial magnetism and exchange coupling in BiFeO3–CuO nanocomposite

    International Nuclear Information System (INIS)

    Ferromagnetic BiFeO3 nanocrystals of average size 9 nm were used to form a composite with antiferromagnetic CuO nanosheets, with the composition (x)BiFeO3/(100−x)CuO, x = 0, 20, 40, 50, 60, 80 and 100. The dispersion of BiFeO3 nanocrystals into the CuO matrix was confirmed by x-ray diffraction and transmission electron microscopy. The ferromagnetic ordering as observed in pure BiFeO3 occurs mainly due to the reduction in the particle size as compared to the wavelength (62 nm) of the spiral modulated spin structure of the bulk BiFeO3. Surface spin disorder of BiFeO3 nanocrystals gives rise to an exponential behavior of magnetization with temperature. Strong magnetic exchange coupling between the BiFeO3 nanocrystal and the CuO matrix induces an interfacial superparamagnetic phase with a blocking temperature of about 80 K. Zero field and field cooled magnetizations are analyzed by a ferromagnetic core and disordered spin shell model. The temperature dependence of the calculated saturation magnetization exhibits three magnetic contributions in three temperature regimes. The BiFeO3/CuO nanocomposites reveal an exchange bias effect below 170 K. The maximum exchange bias field HEB is 1841 Oe for x = 50 at 5 K under field cooling of 50 kOe. The exchange bias coupling results in an increase of coercivity of 1934 Oe at 5 K. Blocked spins within an interfacial region give rise to a remarkable exchange bias effect in the nanocomposite due to strong magnetic exchange coupling between the BiFeO3 nanocrystals and the CuO nanosheets. (paper)

  7. Thin films of soft matter

    CERN Document Server

    Kalliadasis, Serafim

    2007-01-01

    A detailed overview and comprehensive analysis of the main theoretical and experimental advances on free surface thin film and jet flows of soft matter is given. At the theoretical front the book outlines the basic equations and boundary conditions and the derivation of low-dimensional models for the evolution of the free surface. Such models include long-wave expansions and equations of the boundary layer type and are analyzed via linear stability analysis, weakly nonlinear theories and strongly nonlinear analysis including construction of stationary periodic and solitary wave and similarity solutions. At the experimental front a variety of very recent experimental developments is outlined and the link between theory and experiments is illustrated. Such experiments include spreading drops and bubbles, imbibitions, singularity formation at interfaces and experimental characterization of thin films using atomic force microscopy, ellipsometry and contact angle measurements and analysis of patterns using Minkows...

  8. Polycrystalline thin films : A review

    Energy Technology Data Exchange (ETDEWEB)

    Valvoda, V. [Charles Univ., Prague (Czech Republic). Faculty of Mathematics and Physics

    1996-09-01

    Polycrystalline thin films can be described in terms of grain morphology and in terms of their packing by the Thornton`s zone model as a function of temperature of deposition and as a function of energy of deposited atoms. Grain size and preferred grain orientation (texture) can be determined by X-ray diffraction (XRD) methods. A review of XRD analytical methods of texture analysis is given with main attention paid to simple empirical functions used for texture description and for structure analysis by joint texture refinement. To illustrate the methods of detailed structure analysis of thin polycrystalline films, examples of multilayers are used with the aim to show experiments and data evaluation to determine layer thickness, periodicity, interface roughness, lattice spacing, strain and the size of diffraction coherent volumes. The methods of low angle and high angle XRD are described and discussed with respect to their complementary information content.

  9. Organic thin-film photovoltaics

    OpenAIRE

    Liu, Miaoyin

    2010-01-01

    Zusammenfassung Zur Verbesserung der Leistungsumwandlung in organischen Solarzellen sind neue Materialien von zentraler Bedeutung, die sämtliche Erfordernisse für organische Photovoltaik-Elemente erfüllen. In der vorliegenden Arbeit „Organic thin-film photovoltaics“ wurden im Hinblick auf ein besseres Verständnis der Zusammenhänge zwischen molekularer Struktur und der Leistungsfähigkeit neue Materialien in „bulk-heterojunction“ Solarzellen und in Festphasen-Farbstoffsensibilisierten ...

  10. Size-Dependent Infrared Phonon Modes and Ferroelectric Phase Transition in BiFeO3 Nanoparticles

    International Nuclear Information System (INIS)

    One emergent property of ferroelectric nanoparticles is the sized-induced structural distortion to a high-symmetry paraelectric phase at small particle sizes. Finite length scale effects can thus be advantageously employed to elucidate ferroelectric transition mechanisms. In this work, we combine infrared spectroscopy with group theory and lattice dynamics calculations to reveal the displacive nature of the ferroelectric transition in BiFeO3, a room temperature multiferroic. Systematic intensity and frequency trends in selected vibrational modes show that the paraelectric phase is Pm3 m and the lowest frequency A1 feature is the soft mode that drives the first order transition. Finite length scale effects are also evident in the electronic structure with a red-shifted band gap in nanoscale BiFeO3 compared with that of the rhombohedral film, a result that can impact the development of ferroelectric photovoltaics and oxide-based electronics. Taken together, these findings demonstrate the foundational importance of size effects for enhancing the rich functionality and broad utility of transition metal oxides.

  11. Size-Dependent Infrared Phonon Modes and Ferroelectric Phase Transition in BiFeO3 Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Peng [University of Tennessee; Xu, Xiaoshan [ORNL; Koenigsmann, Christopher [State University of New York, Stony Brook; Santulli, Alexander [State University of New York, Stony Brook; Wong, Stanislaus [State University of New York, Stony Brook; Musfeldt, J.L. [University of Tennessee, Knoxville (UTK)

    2010-10-01

    One emergent property of ferroelectric nanoparticles is the sized-induced structural distortion to a high-symmetry paraelectric phase at small particle sizes. Finite length scale effects can thus be advantageously employed to elucidate ferroelectric transition mechanisms. In this work, we combine infrared spectroscopy with group theory and lattice dynamics calculations to reveal the displacive nature of the ferroelectric transition in BiFeO3, a room temperature multiferroic. Systematic intensity and frequency trends in selected vibrational modes show that the paraelectric phase is Pm3 m and the lowest frequency A1 feature is the soft mode that drives the first order transition. Finite length scale effects are also evident in the electronic structure with a red-shifted band gap in nanoscale BiFeO3 compared with that of the rhombohedral film, a result that can impact the development of ferroelectric photovoltaics and oxide-based electronics. Taken together, these findings demonstrate the foundational importance of size effects for enhancing the rich functionality and broad utility of transition metal oxides.

  12. The Photovoltaic Properties of BiFeO3Lao.7Sro.3MnO3 Heterostructures

    Institute of Scientific and Technical Information of China (English)

    LUO Bing-Cheng; CHEN Chang-Le; FAN Fei; JIN Ke-Xin

    2012-01-01

    An epitaxial BiFeO3/La0.7Sr0.3MnO3 (BFO/LSMO) multiferroic heterostructure is grown on an LaAlO3 (001) substrate by laser molecular beam epitaxy,and its photovoltaic properties are investigated.It is found that the photocurrent is significantly increased under illumination,and the short-circuit photocurrent has a linear relationship with the laser intensity.Furthermore,when the ferroelectric polarization of the BFO layer is switched,the short-circuit photocurrent and open-circuit voltage can be switched.These results are discussed by considering the contributions from the ferroelectric polarization and the electrode/film interface.%An epitaxial BifeO3/La0.7Sr0.3Mno3 (BFO/LSMO) multiferroic heterostructure is grown on an LaAIO3. Substrate by laser molecular beam epitaxy, and its photovoltaic properties are investigated. It is found that the photocurrent is significantly increased under illumination, and the short-circuit photocurrent has a linear relationship with the laser intensity. Furthermore, when the ferroelectric polarization of the BFO layer is switched, the short-circuit photocurrent and open-circuit voltage can be switched. These results are discussed by considering the contributions from the ferroelectric polarization and the electrode/rim interface.

  13. SYNTHESIS AND CHARACTERIZATIONS OF PURE AND DOPED NANOCRYSTALLINE BiFeO3 CERAMICS BY SHS

    Directory of Open Access Journals (Sweden)

    YOGESH A. CHAUDHARI

    2014-03-01

    Full Text Available The pure and Zn incorporated BiFeO3 ceramics were synthesized by self-propagating high temperature synthesis (SHS. The X-ray diffractometer (XRD studies revealed that, both BiFeO3 and BiFe0.95Zn0.05O3 ceramics crystallizes in a single phase rhombhohedral structure. The room temperature ferroelectric and magnetic hysteresis loop evidenced coexistence of ferroelectricity and magnetism in single phase undoped and Zn doped BiFeO3. The M-H hysteresis loop of BiFe0.95Zn0.05O3 sample demonstrated a weak ferromagnetism at 300 K and 5 K respectively. The room temperature ferroelectric P-E hysteresis loops of BiFeO3 and BiFe0.95Zn0.05O3 exhibited an unsaturated behavior and suggests a partial reversal of polarization. A variation of dielectric constant with respect to temperature in BiFeO3 and BiFe0.95Zn0.05O3 ceramic delivers a dielectric anomaly around 480 and 450°C which is a consequence of antiferromagnetic to paramagnetic phase transition (TN. Moreover, for BiFeO3 the anomaly manifests a possible coupling between electric and magnetic dipole moments.

  14. Exchange bias effect in BiFeO3-NiO nanocomposite

    Science.gov (United States)

    Chakrabarti, Kaushik; Sarkar, Babusona; Dev Ashok, Vishal; Das, Kajari; Sinha Chaudhuri, Sheli; Mitra, Amitava; De, S. K.

    2014-01-01

    Ferromagnetic BiFeO3 nanocrystals of average size 11 nm were used to form nanocomposites (x)BiFeO3/(100 - x)NiO, x = 0, 20, 40, 50, 60, 80, and 100 by simple solvothermal process. The ferromagnetic BiFeO3 nanocrystals embedded in antiferromagnetic NiO nanostructures were confirmed from X-ray diffraction and transmission electron microscope studies. The modification of cycloidal spin structure of bulk BiFeO3 owing to reduction in particle size compared to its spin spiral wavelength (62 nm) results in ferromagnetic ordering in pure BiFeO3 nanocrystals. High Neel temperature (TN) of NiO leads to significant exchange bias effect across the BiFeO3/NiO interface at room temperature. A maximum exchange bias field of 123.5 Oe at 300 K for x = 50 after field cooling at 7 kOe has been observed. The exchange bias coupling causes an enhancement of coercivity up to 235 Oe at 300 K. The observed exchange bias effect originates from the exchange coupling between the surface uncompensated spins of BiFeO3 nanocrystals and NiO nanostructures.

  15. Induced modifications in the properties of Sr doped BiFeO3 multiferroics

    Institute of Scientific and Technical Information of China (English)

    Tanvir Hussain; Saadat A. Siddiqi; Shahid Atiq; M.S. Awan

    2013-01-01

    Multiferroics exhibit unique combination of ferroic properties, simultaneously. For instance, in BiFeO3, magnetic and electric properties co-exist. In this work, BiFeO3 and Sr-doped BiFeO3 samples with general formula, Bi1 ? xSrxFeO3 (x ¼ 0.00, 0.05, 0.10, 0.20, and 0.30) were synthesized by sol-gel auto-combustion technique, in order to investigate these ferroic properties. The samples were confirmed to have perovskite type rhombohedral structure, characteristic of BiFeO3. A dilute phase of Bi2Fe4O9 was also found in all the Sr-doped samples. The micrographs of the palletized samples revealed that minutely doped Sr might not have any effect on the morphology of the samples. Frequency dependent dielectric measurements were carried out at room temperature for all the samples from 100 Hz to 1 MHz. The dielectric constant of un-doped sample at low frequency was 52 which decreased with increasing Sr doping. An enhancement of magnetic properties was observed with increasing the Sr contents. Pure BiFeO3 material was observed to have the least value of remanent magnetization. As the Sr2þ ions were doped in BiFeO3, its magnetization and remanence were increased to 0.867 emu/g and 0.175 emu/g, respectively, at x ¼ 0.30.

  16. Ferroelectric properties of BiFeO3 ceramics sintered under low oxygen partial pressure

    International Nuclear Information System (INIS)

    BiFeO3 ceramics were prepared in various atmospheres with hydrothermally-synthesized BiFeO3 crystalline powders, and their dielectric and ferroelectric properties were investigated. The single BiFeO3 phase was formed when the sample was sintered at 800 .deg. C under air, and a minor Bi2Fe4O9 phase was observed when it was sintered under a N2 or an Ar atmosphere. The BiFeO3 ceramic sintered under N2 showed a dense microstructure and superior electric properties: a dielectric constant of 75, a low loss tangent of 0.01 at 100 kHz and a high resistivity of 1.37 x 1011 Ω · cm. A pinched and asymmetric P-E hysteresis and a typical butterfly-shaped S-E loop were observed in the BiFeO3 ceramic sintered under N2. The electric properties of BiFeO3 ceramics sintered in various atmospheres are discussed on the basis of defect chemistry.

  17. Weak ferromagnetic ordering in Ca doped polycrystalline BiFeO3

    International Nuclear Information System (INIS)

    Structural and magnetic properties of polycrystalline BiFeO3, Bi0.9Ca0.1FeO2.95, Bi0.9Ba0.05Ca0.05FeO2.95, and Bi0.9Ba0.1FeO2.95 ceramic samples were studied to establish the effects of doping in BiFeO3 on the magnetic property. X-ray diffraction data of the undoped and doped BiFeO3 samples were refined to a rhombohedral structure with space group R3c. X-ray photoelectron spectroscopy study showed the formation of a single-phase in both the undoped and doped BiFeO3 ceramics with Fe in the 3+ valence state. Ca doped and Ba-Ca co-doped BiFeO3 ceramic samples show weak ferromagnetic ordering at room temperature. This observation makes Ca doped and Ba-Ca co-doped BiFeO3 samples an interesting material system for magnetoelectric coupling studies.

  18. Fabrication, Characterization, Properties, and Applications of Low-Dimensional BiFeO3 Nanostructures

    Directory of Open Access Journals (Sweden)

    Heng Wu

    2014-01-01

    Full Text Available Low-dimensional BiFeO3 nanostructures (e.g., nanocrystals, nanowires, nanotubes, and nanoislands have received considerable attention due to their novel size-dependent properties and outstanding multiferroic properties at room temperature. In recent years, much progress has been made both in fabrications and (microstructural, electrical, and magnetic in characterizations of BiFeO3 low-dimensional nanostructures. An overview of the state of art in BiFeO3 low-dimensional nanostructures is presented. First, we review the fabrications of high-quality BiFeO3 low-dimensional nanostructures via a variety of techniques, and then the structural characterizations and physical properties of the BiFeO3 low-dimensional nanostructures are summarized. Their potential applications in the next-generation magnetoelectric random access memories and photovoltaic devices are also discussed. Finally, we conclude this review by providing our perspectives to the future researches of BiFeO3 low-dimensional nanostructures and some key problems are also outlined.

  19. Photoconductivity of thin organic films

    International Nuclear Information System (INIS)

    Thin organic films were deposited on silicon oxide surfaces with golden interdigitated electrodes (interelectrode gap was 2 μm), and the film resistivities were measured in dark and under white light illumination. The compounds selected for the measurements include molecules widely used in solar cell applications, such as polythiophene (PHT), fullerene (C60), pyrelene tetracarboxylic diimide (PTCDI) and copper phthalocyanine (CuPc), as well as molecules potentially interesting for photovoltaic applications, e.g. porphyrin-fullerene dyads. The films were deposited using thermal evaporation (e.g. for C60 and CuPc films), spin coating for PHT, and Langmuir-Schaeffer for the layer-by-layer deposition of porphyrin-fullerene dyads. The most conducting materials in the series are films of PHT and CuPc with resistivities 1.2 x 103 Ω m and 3 x 104 Ω m, respectively. Under light illumination resistivity of all films decreases, with the strongest light effect observed for PTCDI, for which resistivity decreases by 100 times, from 3.2 x 108 Ω m in dark to 3.1 x 106 Ω m under the light.

  20. Electrical and magnetic properties of single-phased and highly resistive ferroelectromagnet BiFeO3 ceramic

    International Nuclear Information System (INIS)

    Investigation of BiFeO3 is being conducted intensively. However, preparing perfect samples with high resistance is still a prerequisite for the clarification of the properties of BiFeO3. Here we report electrical and magnetic properties and phase transitions of BiFeO3 ceramic synthesized by a rapid sintering processing. The dependence of the sintering products on the sintering temperatures revealed that single-phased BiFeO3 ceramic was synthesized at 880 deg, C using this rapid sintering technique. The as-prepared BiFeO3 sample shows a high resistivity of 6.7 x 1010Ω cm at an external electric field of 100 kVcm-1. Vibrating sample magnetometer (VSM) measurement verified that the high resistance BiFeO3 ceramic presented an antiferromagnetic characterization

  1. Zinc oxide thin film acoustic sensor

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, Ali Jasim; Salih, Wafaa Mahdi; Hassan, Marwa Abdul Muhsien; Nusseif, Asmaa Deiaa; Kadhum, Haider Abdullah [Department of Physics , College of Science, Al-Mustansiriyah University, Baghdad (Iraq); Mansour, Hazim Louis [Department of Physics , College of Education, Al-Mustansiriyah University, Baghdad (Iraq)

    2013-12-16

    This paper reports the implementation of (750 nm) thickness of Zinc Oxide (ZnO) thin film for the piezoelectric pressure sensors. The film was prepared and deposited employing the spray pyrolysis technique. XRD results show that the growth preferred orientation is the (002) plane. A polycrystalline thin film (close to mono crystallite like) was obtained. Depending on the Scanning Electron Microscopy photogram, the film homogeneity and thickness were shown. The resonance frequency measured (about 19 kHz) and the damping coefficient was calculated and its value was found to be about (2.5538), the thin film be haves as homogeneous for under and over damped. The thin film pressure sensing was approximately exponentially related with frequency, the thin film was observed to has a good response for mechanical stresses also it is a good material for the piezoelectric properties.

  2. Flexible Tactile Sensor Using Polyurethane Thin Film

    OpenAIRE

    Seiji Aoyagi; Tomokazu Takahashi; Masato Suzuki

    2012-01-01

    A novel capacitive tactile sensor using a polyurethane thin film is proposed in this paper. In previous studies, capacitive tactile sensors generally had an air gap between two electrodes in order to enhance the sensitivity. In this study, there is only polyurethane thin film and no air gap between the electrodes. The sensitivity of this sensor is higher than the previous capacitive tactile sensors because the polyurethane is a fairly flexible elastomer and the film is very thin (about 1 µm)....

  3. Silicon Thin-Film Solar Cells

    OpenAIRE

    2007-01-01

    We review the field of thin-film silicon solar cells with an active layer thickness of a few micrometers. These technologies can potentially lead to low cost through lower material costs than conventional modules, but do not suffer from some critical drawbacks of other thin-film technologies, such as limited supply of basic materials or toxicity of the components. Amorphous Si technology is the oldest and best established thin-film silicon technology. Amorphous silicon is deposited at low t...

  4. Capturing ultrafast photoinduced local structural distortions of BiFeO3.

    Science.gov (United States)

    Wen, Haidan; Sassi, Michel; Luo, Zhenlin; Adamo, Carolina; Schlom, Darrell G; Rosso, Kevin M; Zhang, Xiaoyi

    2015-01-01

    The interaction of light with materials is an intensively studied research forefront, in which the coupling of radiation energy to selective degrees of freedom offers contact-free tuning of functionalities on ultrafast time scales. Capturing the fundamental processes and understanding the mechanism of photoinduced structural rearrangement are essential to applications such as photo-active actuators and efficient photovoltaic devices. Using ultrafast x-ray absorption spectroscopy aided by density functional theory calculations, we reveal the local structural arrangement around the transition metal atom in a unit cell of the photoferroelectric archetype BiFeO3 film. The out-of-plane elongation of the unit cell is accompanied by the in-plane shrinkage with minimal change of interaxial lattice angles upon photoexcitation. This anisotropic elastic deformation of the unit cell is driven by localized electric field as a result of photoinduced charge separation, in contrast to a global lattice constant increase and lattice angle variations as a result of heating. The finding of a photoinduced elastic unit cell deformation elucidates a microscopic picture of photocarrier-mediated non-equilibrium processes in polar materials. PMID:26463128

  5. Enhancement of switching speed of BiFeO3 capacitors by magnetic fields

    Directory of Open Access Journals (Sweden)

    E. J. Guo

    2014-09-01

    Full Text Available The effect of a magnetic field on the ferroelectric switching kinetics of BiFeO3 (BFO capacitors with La0.8Ca0.2MnO3 (LCMO bottom electrode and Pt top contact has been investigated. We find a strong dependence of the remnant polarization and coercive field on the magnetic field. The switching time can be systematically tuned by magnetic field and reaches a tenfold reduction around the Curie temperature of LCMO at 4 T. We attribute this behavior to the splitting of the voltage drops across the BFO film and the LCMO bottom electrode, which can be strongly influenced by an external magnetic field due to the magnetoresistance. Further experiments on the BFO capacitors with SrRuO3 bottom electrodes show little magnetic field dependence of ferroelectric switching confirming our interpretation. Our results provide an efficient route to control the ferroelectric switching speed through the magnetic field, implying potential application in multifunctional devices.

  6. Thin films for emerging applications v.16

    CERN Document Server

    Francombe, Maurice H

    1992-01-01

    Following in the long-standing tradition of excellence established by this serial, this volume provides a focused look at contemporary applications. High Tc superconducting thin films are discussed in terms of ion beam and sputtering deposition, vacuum evaporation, laser ablation, MOCVD, and other deposition processes in addition to their ultimate applications. Detailed treatment is also given to permanent magnet thin films, lateral diffusion and electromigration in metallic thin films, and fracture and cracking phenomena in thin films adhering to high-elongation substrates.

  7. Minerals deposited as thin films

    International Nuclear Information System (INIS)

    Free matrix effects are due to thin film deposits. Thus, it was decided to investigate this technique as a possibility to use pure oxide of the desired element, extrapolating its concentration from analytical curves made with avoiding, at the same time, mathematical corrections. The proposed method was employed to determine iron and titanium concentrations in geological samples. The range studied was 0.1-5%m/m for titanium and 5-20%m/m for iron. For both elements the reproducibility was about 7% and differences between this method and other chemical determinations were 15% for titanium and 7% for iron. (Author)

  8. Interactions in thin aqueous films

    OpenAIRE

    Hänni-Ciunel, Katarzyna

    2006-01-01

    In der Arbeit werden die Wechselwirkungen in dünnen flüssigen Filmen untersucht und modifiziert. Schaum- (gas/flüssig/gas) und Benetzungsfilme (gas/flüssig/fest) werden mittels Thin Film Pressure Balance (TFPB) untersucht. Die Apparatur wurde im Rahmen der Arbeit für die Studien an asymmetrischen Filmen aufgebaut und modifiziert. Die Ladungen an den Filmgrenzflächen werden gezielt modifiziert. Die Adsoprtion von Tensiden bestimmt die Oberflächenladung an der gas/flüssig Grenzfläche. Die Oberf...

  9. The role of thin films in wetting

    OpenAIRE

    Marmur, Abraham

    1988-01-01

    The role of thin films in wetting is reviewed. Three modes of spontaneous spreading are discussed : incomplete spreading, complete spreading and mixed-mode spreading. A thin film can be either molecular or colloidal in thickness. Molecularly adsorbed films are mainly associated with incomplete spreading. Colloidal films usually extend from the bulk of the liquid in dynamic situations of complete spreading. Their existence at equilibriuim with the bulk depends on the orientation in the gravita...

  10. Microstructural evolution of tungsten oxide thin films

    International Nuclear Information System (INIS)

    Tungsten oxide thin films are of great interest due to their promising applications in various optoelectronic thin film devices. We have investigated the microstructural evolution of tungsten oxide thin films grown by DC magnetron sputtering on silicon substrate. The structural characterization and surface morphology were carried out using X-ray diffraction and Scanning Electron Microscopy (SEM). The as deposited films were amorphous, where as, the films annealed above 400 deg. were crystalline. In order to explain the microstructural changes due to annealing, we have proposed a 'instability wheel' model for the evolution of the microstructure. This model explains the transformation of mater into various geometries within them selves, followed by external perturbation.

  11. Thin liquid films dewetting and polymer flow

    CERN Document Server

    Blossey, Ralf

    2012-01-01

    This book is a treatise on the thermodynamic and dynamic properties of thin liquid films at solid surfaces and, in particular, their rupture instabilities. For the quantitative study of these phenomena, polymer thin films haven proven to be an invaluable experimental model system.   What is it that makes thin film instabilities special and interesting, warranting a whole book? There are several answers to this. Firstly, thin polymeric films have an important range of applications, and with the increase in the number of technologies available to produce and to study them, this range is likely to expand. An understanding of their instabilities is therefore of practical relevance for the design of such films.   Secondly, thin liquid films are an interdisciplinary research topic. Interdisciplinary research is surely not an end to itself, but in this case it leads to a fairly heterogeneous community of theoretical and experimental physicists, engineers, physical chemists, mathematicians and others working on the...

  12. Synthesis, microstructure and properties of BiFeO3-based multiferroic materials: A review

    Directory of Open Access Journals (Sweden)

    Bernardo, M. S.

    2014-02-01

    Full Text Available BiFeO3-based materials are currently one of the most studied multiferroics due to their possible applications at room temperature. However, among the large number of published papers there is much controversy. For example, possibility of synthesizing a pure BiFeO3 phase is still source of discussion in literature. Not even the nature of the binary Bi2O3-Fe2O3 diagram has been clarified yet. The difficulty in controlling the formation of parasite phases reaches the consolidation step. Accordingly, the sintering conditions must be carefully determined both to get dense materials and to avoid bismuth ferrite decomposition. However, the precise conditions to attain dense bismuth ferrite materials are frequently contradictory among different works. As a consequence, the reported properties habitually result opposed and highly irreproducible hampering the preparation of BiFeO3 materials suitable for practical applications. In this context, the purpose of the present review is to summarize the main researches regarding BiFeO3 synthesis, microstructure and properties in order to provide an easier understanding of these materials.Los materiales basados en BiFeO3 son en la actualidad uno de los multiferroicos más estudiados debido a sus posibles aplicaciones a temperatura ambiente. Sin embargo, entre la multitud de trabajos publicados referentes a estos materiales existe mucha controversia. Por ejemplo, la posibilidad de sintetizar una fase BiFeO3 pura es aún objeto de discusión en la bibliografía y la naturaleza de los diagramas de fases del sistema Bi2O3-Fe2O3 aún no está clara. La dificultad para controlar las fases parásitas se extiende al proceso de consolidación por lo que las condiciones de sinterización deben ser cuidadosamente controladas para obtener materiales densos y al mismo tiempo evitar la descomposición de la ferrita. No obstante, las condiciones precisas para obtener materiales densos de BiFeO3 son frecuentemente contradictorias entre los distintos trabajos. Como consecuencia, las propiedades descritas son a menudo discordantes y poco reproducibles impidiendo la preparación de materiales de BiFeO3 adecuados para sus aplicaciones prácticas. En este contexto, el propósito de esta revisión es resumir las principales investigaciones en torno a la síntesis, microestructura y propiedades de los materiales de BiFeO3 facilitando así la comprensión de los mismos.

  13. Ellipsometric Studies on Silver Telluride Thin Films

    Directory of Open Access Journals (Sweden)

    M. Pandiaraman

    2011-01-01

    Full Text Available Silver telluride thin films of thickness between 45 nm and 145 nm were thermally evaporated on well cleaned glass substrates at high vacuum better than 10 – 5 mbar. Silver telluride thin films are polycrystalline with monoclinic structure was confirmed by X-ray diffractogram studies. AFM and SEM images of these films are also recorded. The phase ratio and amplitude ratio of these films were recorded in the wavelength range between 300 nm and 700 nm using spectroscopic ellipsometry and analysed to determine its optical band gap, refractive index, extinction coefficient, and dielectric functions. High absorption coefficient determined from the analysis of recorded spectra indicates the presence of direct band transition. The optical band gap of silver telluride thin films is thickness dependent and proportional to square of reciprocal of thickness. The dependence of optical band gap of silver telluride thin films on film thickness has been explained through quantum size effect.

  14. Synthesis and characterization of BiFeO3 for photocatalytic degradation of azo dye

    International Nuclear Information System (INIS)

    A novel approach is reported to synthesize single phase BiFeO3 via. sol-gel auto combustion method using glycine as fuel. Synthesized powder was subjected to annealing at different temperatures, i.e. 400 °C, 450 °C, 500 °C, 550 °C, and 600°C. Crystal structure of BiFeO3 samples examined by X-ray diffraction indicates that the samples were single-phased with different particle sizes, as particle sizes are temperature dependent and crystallized in rhombohedral structure. As the temperature was increased, the diffraction peak intensity of BiFeO3 in the XRD spectra gradually enhanced and the diffraction peaks became sharper. The optical properties of the resultant BiFeO3 were characterized using UV-Vis spectrophotometer over the range of 350-800 nm. UV-vis spectra of all the samples indicate that optical band gap lies in the visible region in the range of 2.2-2.07 eV at all temperatures. Moreover, photocatalytic properties of the BiFeO3 powders were investigated by the photodegradation of Reactive Black-5 (RB-5)

  15. Synthesis and characterization of BiFeO3 for photocatalytic degradation of azo dye

    Science.gov (United States)

    Kaur, Manpreet; Uniyal, Poonam

    2015-08-01

    A novel approach is reported to synthesize single phase BiFeO3 via. sol-gel auto combustion method using glycine as fuel. Synthesized powder was subjected to annealing at different temperatures, i.e. 400 °C, 450 °C, 500 °C, 550 °C, and 600°C. Crystal structure of BiFeO3 samples examined by X-ray diffraction indicates that the samples were single-phased with different particle sizes, as particle sizes are temperature dependent and crystallized in rhombohedral structure. As the temperature was increased, the diffraction peak intensity of BiFeO3 in the XRD spectra gradually enhanced and the diffraction peaks became sharper. The optical properties of the resultant BiFeO3 were characterized using UV-Vis spectrophotometer over the range of 350-800 nm. UV-vis spectra of all the samples indicate that optical band gap lies in the visible region in the range of 2.2-2.07 eV at all temperatures. Moreover, photocatalytic properties of the BiFeO3 powders were investigated by the photodegradation of Reactive Black-5 (RB-5).

  16. Electrostatic thin film chemical and biological sensor

    Science.gov (United States)

    Prelas, Mark A.; Ghosh, Tushar K.; Tompson, Jr., Robert V.; Viswanath, Dabir; Loyalka, Sudarshan K.

    2010-01-19

    A chemical and biological agent sensor includes an electrostatic thin film supported by a substrate. The film includes an electrostatic charged surface to attract predetermined biological and chemical agents of interest. A charge collector associated with said electrostatic thin film collects charge associated with surface defects in the electrostatic film induced by the predetermined biological and chemical agents of interest. A preferred sensing system includes a charge based deep level transient spectroscopy system to read out charges from the film and match responses to data sets regarding the agents of interest. A method for sensing biological and chemical agents includes providing a thin sensing film having a predetermined electrostatic charge. The film is exposed to an environment suspected of containing the biological and chemical agents. Quantum surface effects on the film are measured. Biological and/or chemical agents can be detected, identified and quantified based on the measured quantum surface effects.

  17. Structure, synthesis and multiferroic nature of BiFeO3 and 0.9BiFeO3–0.1BaTiO3: An overview

    Indian Academy of Sciences (India)

    Dhananjai Pandey; Anar Singh

    2009-06-01

    A brief review of the crystal structure and multiferroic nature of pure BiFeO3 and 0.9BiFeO3–0.1BaTiO3 (BF–0.1BT) is presented. An atomic level evidence for magnetoelectric coupling of intrinsic multiferroic origin in BF–0.1BT is presented.

  18. Nanostructured thin films and coatings functional properties

    CERN Document Server

    Zhang, Sam

    2010-01-01

    The second volume in ""The Handbook of Nanostructured Thin Films and Coatings"" set, this book focuses on functional properties, including optical, electronic, and electrical properties, as well as related devices and applications. It explores the large-scale fabrication of functional thin films with nanoarchitecture via chemical routes, the fabrication and characterization of SiC nanostructured/nanocomposite films, and low-dimensional nanocomposite fabrication and applications. The book also presents the properties of sol-gel-derived nanostructured thin films as well as silicon nanocrystals e

  19. Strain Localization in Thin Films of Bi(Fe,Mn)O3 Due to the Formation of Stepped Mn(4+)-Rich Antiphase Boundaries.

    Science.gov (United States)

    MacLaren, I; Sala, B; Andersson, S M L; Pennycook, T J; Xiong, J; Jia, Q X; Choi, E-M; MacManus-Driscoll, J L

    2015-12-01

    The atomic structure and chemistry of thin films of Bi(Fe,Mn)O3 (BFMO) films with a target composition of Bi2FeMnO6 on SrTiO3 are studied using scanning transmission electron microscopy imaging and electron energy loss spectroscopy. It is shown that Mn(4+)-rich antiphase boundaries are locally nucleated right at the film substrate and then form stepped structures that are approximately pyramidal in three dimensions. These have the effect of confining the material below the pyramids in a highly strained state with an out-of-plane lattice parameter close to 4.1 Å. Outside the area enclosed by the antiphase boundaries, the out-of-plane lattice parameter is much closer to bulk values for BFMO. This suggests that to improve the crystallographic perfection of the films whilst retaining the strain state through as much of the film as possible, ways need to be found to prevent nucleation of the antiphase boundaries. Since the antiphase boundaries seem to form from the interaction of Mn with the Ti in the substrate, one route to perform this would be to grow a thin buffer layer of pure BiFeO3 on the SrTiO3 substrate to minimise any Mn-Ti interactions. PMID:26474888

  20. PREPARATION AND CHARACTERIZATION OF POLY-CRYSTALLINE SILICON THIN FILM

    Institute of Scientific and Technical Information of China (English)

    Y.F. Hu; H. Shen; Z.Y. Liu; L.S. Wen

    2003-01-01

    Poly-crystalline silicon thin film has big potential of reducing the cost of solar cells.In this paper the preparation of thin film is introduced, and then the morphology of poly-crystalline thin film is discussed. On the film we developed poly-crystalline silicon thin film solar cells with efficiency up to 6. 05% without anti-reflection coating.

  1. Thermal Expansion Coefficients of Thin Crystal Films

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The formulas for atomic displacements and Hamiltonian of a thin crystal film in phonon occupation number representation are obtained with the aid of Green's function theory. On the basis of these results, the formulas for thermal expansion coefficients of the thin crystal film are derived with the perturbation theory, and the numerical calculations are carried out. The results show that the thinner films have larger thermal expansion coefficients.

  2. Slip-controlled thin film dynamics

    OpenAIRE

    Fetzer, R.; Rauscher, M; Münch, A.; Wagner, B. A.; Jacobs, K.

    2006-01-01

    In this study, we present a novel method to assess the slip length and the viscosity of thin films of highly viscous Newtonian liquids. We quantitatively analyse dewetting fronts of low molecular weight polystyrene melts on Octadecyl- (OTS) and Dodecyltrichlorosilane (DTS) polymer brushes. Using a thin film (lubrication) model derived in the limit of large slip lengths, we can extract slip length and viscosity. We study polymer films with thicknesses between 50 nm and 230 nm and various tempe...

  3. BDS thin film damage competition

    Energy Technology Data Exchange (ETDEWEB)

    Stolz, C J; Thomas, M D; Griffin, A J

    2008-10-24

    A laser damage competition was held at the 2008 Boulder Damage Symposium in order to determine the current status of thin film laser resistance within the private, academic, and government sectors. This damage competition allows a direct comparison of the current state-of-the-art of high laser resistance coatings since they are all tested using the same damage test setup and the same protocol. A normal incidence high reflector multilayer coating was selected at a wavelength of 1064 nm. The substrates were provided by the submitters. A double blind test assured sample and submitter anonymity so only a summary of the results are presented here. In addition to the laser resistance results, details of deposition processes, coating materials, and layer count will also be shared.

  4. Thin-film optical shutter

    Science.gov (United States)

    Matlow, S. L.

    1981-02-01

    The ideal solution to the excessive solar gain problem is an optical shutter, a device which switches from being highly transmissive to solar radiation to being highly reflective to solar radiation when a critical temperature is reached in the enclosure. The switching occurs because one or more materials in the device undergo a phase transition at the critical temperature. A specific embodiment of macroconjugated macromolecules, the poly (p-phenylene)'s, was chosen as the one most likely to meet all of the requirements of the thin film optical shutter project (TFOS). The reason for this choice is explored. In order to be able to make meaningful calculations of the thermodynamic and optical properties of the poly (p-phenylene)'s a quantum mechanical method, the equilibrium bond length (EBL) theory, was developed. Some results of EBL theory are included.

  5. Resistive memory effects in BiFeO3 single crystals controlled by transverse electric fields

    Science.gov (United States)

    Kawachi, S.; Kuroe, H.; Ito, T.; Miyake, A.; Tokunaga, M.

    2016-04-01

    The effects of electric fields perpendicular to the c-axis of the trigonal cell in single crystals of BiFeO3 are investigated through magnetization and resistance measurements. Magnetization and resistance exhibit hysteretic changes under applied electric fields, which can be ascribed to the reorientation of the magnetoelectric domains. Samples are repetitively switched between high- and low-resistance states by changing the polarity of the applied electric fields over 20 000 cycles at room temperature. These results demonstrate the potential of BiFeO3 for use in non-volatile memory devices.

  6. Size effect study in magnetoelectric BiFeO3 system

    Indian Academy of Sciences (India)

    Shwetha Shetty; V R Palkar; R Pinto

    2002-05-01

    In this paper, we report for the first time finite size effects on Néel temperature (N) of magnetoelectric BiFeO3 system. Novel wet chemical route has been developed to produce fine particles of BiFeO3 with controlled size and size distribution. Unlike other oxide systems, lattice volume contraction has been observed with decrease in particle size. The decrease in N is co-related to unit cell volume contraction occurring with reduction in particle size.

  7. Plasmonic modes in thin films: quo vadis?

    Directory of Open Access Journals (Sweden)

    AntonioPolitano

    2014-07-01

    Recent calculations indicate the emergence of acoustic surface plasmons (ASP in Ag thin films exhibiting quantum well states and in graphene films. The slope of the dispersion of ASP decreases with film thickness. We also discuss open issues in research on plasmonic modes in graphene/metal interfaes.

  8. Magnetization in permalloy thin films

    Indian Academy of Sciences (India)

    Rachana Gupta; Mukul Gupta; Thomas Gutberlet

    2008-11-01

    Thin films of permalloy (Ni80Fe20) were prepared using an Ar+N2 mixture with magnetron sputtering technique at ambient temperature. The film prepared with only Ar gas shows reflections corresponding to the permalloy phase in X-ray diffraction (XRD) pattern. The addition of nitrogen during sputtering results in broadening of the peaks in XRD pattern, which finally leads to an amorphous phase. The - loop for the sample prepared with only Ar gas is matching well with the values obtained for the permalloy. For the samples prepared with increased nitrogen partial pressure the magnetic moment decreased rapidly and the values of coercivity increased. The polarized neutron reflectivity measurements (PNR) were performed in the sample prepared with only Ar gas and with nitrogen partial pressure of 5 and 10%. It was found that the spin-up and spin-down reflectivities show exactly similar reflectivity for the sample prepared with Ar gas alone, while PNR measurements on 5 and 10% sample show splitting in the spin-up and spin-down reflectivity.

  9. Synthesis and characterization of BiFeO3 nanotube arrays and Y-junction BiFeO3 nanotubes

    Institute of Scientific and Technical Information of China (English)

    LI ChunYang; LIU Bing; ZHAO JianPo; WANG JiangFeng; HU BinBin; DU ZuLiang

    2009-01-01

    Multiferroic BiFeO3(BFO) nanotube arrays (-100 nm in diameter and-50 μm in length) were synthesized by the sol-gel method utilizing the anodic aluminum oxide (AAO) membrane technique. The micro-structure and chemical components of the BFO nanotubes were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectrometer (XPS). The BFO nanotubes exhibited polycrystalline microstructures. The novel Y-junction BFO nano-tubes were simultaneously fabricated.

  10. TiO2 thin film photocatalyst

    Institute of Scientific and Technical Information of China (English)

    YU Jiaguo

    2004-01-01

    It is well known that the photocatalytic activity of TiO2 thin films strongly depends on the preparing methods and post-treatment conditions, since they have a decisive influence on the chemical and physical properties of TiO2 thin films.Therefore, it is necessary to elucidate the influence of the preparation process and post-treatment conditions on the photocatalytic activity and surface microstructures of the films. This review deals with the preparation of TiO2 thin film photocatalysts by wet-chemical methods (such as sol-gel, reverse micellar and liquid phase deposition) and the comparison of various preparation methods as well as their advantage and disadvantage. Furthermore, it is discussed that the advancement of photocatalytic activity, super-hydrophilicity and bactericidal activity of TiO2 thin film photocatalyst in recent years.

  11. Alumina Thin Film Growth: Experiments and Modeling

    OpenAIRE

    Wallin, Erik

    2007-01-01

    The work presented in this thesis deals with experimental and theoretical studies related to the growth of crystalline alumina thin films. Alumina, Al2O3, is a polymorphic material utilized in a variety of applications, e.g., in the form of thin films. Many of the possibilities of alumina, and the problems associated with thin film synthesis of the material, are due to the existence of a range of different crystalline phases. Controlling the formation of the desired phase and the transformati...

  12. Electrochromism of amorphous ruthenium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Se-Hee; Liu, Ping; Tracy, C. Edwin; Deb, Satyen K. [National Renewable Energy Laboratory, Center for Basic Sciences, 1617 Cole Boulevard, Golden, CO 80401 (United States); Cheong, Hyeonsik M. [Sogang University, Shinsoo-Dong, Seoul 121-742 (Korea, Republic of)

    2003-12-01

    We report on the electrochromic behavior of amorphous ruthenium oxide thin films and their electrochemical characteristics for use as counterelectrodes for electrochromic devices. Hydrous ruthenium oxide thin films were prepared by cyclic voltammetry on ITO coated glass substrates from an aqueous ruthenium chloride solution. The cyclic voltammograms of this material show the capacitive behavior including two redox reaction peaks in each cathodic and anodic scan. The ruthenium oxide thin film electrode exhibits a 50% modulation of optical transmittance at 670 nm wavelength with capacitor charge/discharge.

  13. Technology of Environmental Thin Film

    International Nuclear Information System (INIS)

    This book indicates environment and surface engineering with technical term, the newest and eco-friendly technology, surface engineering and thick film, technology of surface analysis and reality test, present condition of electronic component in business, physical vapor deposition method, chemical vapor deposition method, plasma assisted etching, part materials of every functional film and manufacturing method, film resistance materials, film gene materials, total using of various film, film superconductivity materials, and photo electricity film.

  14. Research on Advanced Thin Film Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Goldner, Ronald B. [Tufts Univ., Medford, MA (United States)

    2003-11-24

    During the past 7 years, the Tufts group has been carrying out research on advanced thin film batteries composed of a thin film LiCo02 cathode (positive electrode), a thin film LiPON (lithium phosphorous oxynitride) solid electrolyte, and a thin film graphitic carbon anode (negative electrode), under grant DE FG02-95ER14578. Prior to 1997, the research had been using an rfsputter deposition process for LiCoOi and LiPON and an electron beam evaporation or a controlled anode arc evaporation method for depositing the carbon layer. The pre-1997 work led to the deposition of a single layer cell that was successfully cycled for more than 400 times [1,2] and the research also led to the deposition of a monolithic double-cell 7 volt battery that was cycled for more than 15 times [3]. Since 1997, the research has been concerned primarily with developing a research-worthy and, possibly, a production-worthy, thin film deposition process, termed IBAD (ion beam assisted deposition) for depositing each ofthe electrodes and the electrolyte of a completely inorganic solid thin film battery. The main focus has been on depositing three materials - graphitic carbon as the negative electrode (anode), lithium cobalt oxide (nominally LiCoCb) as the positive electrode (cathode), and lithium phosphorus oxynitride (LiPON) as the electrolyte. Since 1998, carbon, LiCoOa, and LiPON films have been deposited using the IBAD process with the following results.

  15. Finite-temperature properties of multiferroic BiFeO3

    DEFF Research Database (Denmark)

    Kornev, Igor; Lisenkov, S; Haumont, R; Dkhil, B; Bellaiche, L

    2007-01-01

    An effective Hamiltonian scheme is developed to study finite-temperature properties of multiferroic BiFeO3. This approach reproduces very well (i) the symmetry of the ground state, (ii) the Néel and Curie temperatures, and (iii) the intrinsic magnetoelectric coefficients (that are very weak). Thi...

  16. Local Weak Ferromagnetism in Single-Crystalline Ferroelectric BiFeO3

    DEFF Research Database (Denmark)

    Ramazanoglu, M.; Laver, Mark; Ratcliff, W.; Watson, S.M.; Chen, W.C.; Jackson, A.; Kothapalli, K.; Lee, S.; Cheong, S.-W.; Kiryukhin, V.

    2011-01-01

    Polarized small-angle neutron scattering studies of single-crystalline multiferroic BiFeO3 reveal a long-wavelength spin density wave generated by ∼1° spin canting of the spins out of the rotation plane of the antiferromagnetic cycloidal order. This signifies weak ferromagnetism within mesoscopic...

  17. Temperature Dependent Structure of BiFeO3: Probing For Spin Lattice Correlations

    Science.gov (United States)

    Tyson, Trevor; Yu, Tian; Zhang, Han; Abeykoon, Milinda

    The local structure of BiFeO3 has been measured over a broad range of temperatures and in magnetic fields. This detailed study explores the nature of the coupling of magnetism and with the lattice on crossing magnetic transitions. Estimates on the structural changes are given. This work is supported by DOE Grant DE-FG02-07ER46402.

  18. Magnetic dispersion and anisotropy in multiferroic BiFeO3

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Masaaki [ORNL; Fishman, Randy Scott [ORNL; Hong, Tao [ORNL; Lee, C. H. [AIST, Japan; Ushiyama, T. [AIST, Japan; Yanagisawa, Y. [AIST, Japan; Tomioka, Y. [AIST, Japan; Ito, T. [AIST, Japan

    2012-01-01

    We have determined the full magnetic dispersion relations of multiferroic BiFeO3. In particular, two excitation gaps originating from magnetic anisotropies have been clearly observed. The direct observation of the gaps enables us to accurately determine the Dzyaloshinskii-Moriya (DM) interaction and the single ion anisotropy. The DM interaction supports a sizable magneto-electric coupling in this compound.

  19. Synthesis, microstructure and properties of BiFeO3-based multiferroic materials: A review

    International Nuclear Information System (INIS)

    BiFeO3-based materials are currently one of the most studied multiferroics due to their possible applications at room temperature. However, among the large number of published papers there is much controversy. For example, possibility of synthesizing a pure BiFeO3 phase is still source of discussion in literature. Not even the nature of the binary Bi2O3-Fe2O3 diagram has been clarified yet. The difficulty in controlling the formation of parasite phases reaches the consolidation step. Accordingly, the sintering conditions must be carefully determined both to get dense materials and to avoid bismuth ferrite decomposition. However, the precise conditions to attain dense bismuth ferrite materials are frequently contradictory among different works. As a consequence, the reported properties habitually result opposed and highly irreproducible hampering the preparation of BiFeO3 materials suitable for practical applications. In this context, the purpose of the present review is to summarize the main researches regarding BiFeO3 synthesis, microstructure and properties in order to provide an easier understanding of these materials. (Author)

  20. Direct mechanosynthesis of pure BiFeO3 perovskite nanoparticles: reaction mechanism

    Czech Academy of Sciences Publication Activity Database

    Perejon, A.; Murafa, Nataliya; Sanchez-Jimenez, P.E.; Criado, J. M.; Šubrt, Jan; Dianez, MJ.; Peréz-Maqueda, L. A.

    2013-01-01

    Roč. 1, č. 22 (2013), s. 3551-3562. ISSN 2050-7526 Institutional support: RVO:61388980 Keywords : LOW-TEMPERATURE SYNTHESIS * SOLID-STATE SYNTHESIS * MULTIFERROIC BIFEO3 * RAMAN-SCATTERING * BISMUTH FERRITE Subject RIV: CA - Inorganic Chemistry

  1. Permanent laser conditioning of thin film optical materials

    Science.gov (United States)

    Wolfe, C. Robert; Kozlowski, Mark R.; Campbell, John H.; Staggs, Michael; Rainer, Frank

    1995-01-01

    The invention comprises a method for producing optical thin films with a high laser damage threshold and the resulting thin films. The laser damage threshold of the thin films is permanently increased by irradiating the thin films with a fluence below an unconditioned laser damage threshold.

  2. Phase transformation kinetics in thin films

    International Nuclear Information System (INIS)

    This book contains papers presented at the materials Research Society Symposium on Phase Transformations Kinetics in Thin Films held in Anaheim, California from April 29 through May 1, 1991. This symposium provided a multidisciplinary forum for explorations, on experimental and theoretical levels, of thin film reactions and stability, phase nucleation and growth, and amorphization. The papers in this volume, refereed by the peer review process, are organized according to materials and techniques and do not reflect the order of presentations at the symposium. Symposium sessions were organized in the areas of thin-film crystallization, solid-state amorphization, interfacial reactions, solid-state transformations, phase-change optical media and ferroelectric thin films. Contributed papers ranged from theoretical determination of the limits to melt nucleation to commercial concerns of processing techniques for specific properties. Despite this breadth, the similarity of experimental techniques and thermodynamic underpinnings for most of the materials provided a common basis for discussions

  3. Highly stretchable wrinkled gold thin film wires

    International Nuclear Information System (INIS)

    With the growing prominence of wearable electronic technology, there is a need to improve the mechanical reliability of electronics for more demanding applications. Conductive wires represent a vital component present in all electronics. Unlike traditional planar and rigid electronics, these new wearable electrical components must conform to curvilinear surfaces, stretch with the body, and remain unobtrusive and low profile. In this paper, the piezoresistive response of shrink induced wrinkled gold thin films under strain demonstrates robust conductive performance in excess of 200% strain. Importantly, the wrinkled metallic thin films displayed negligible change in resistance of up to 100% strain. The wrinkled metallic wires exhibited consistent performance after repetitive strain. Importantly, these wrinkled thin films are inexpensive to fabricate and are compatible with roll to roll manufacturing processes. We propose that these wrinkled metal thin film wires are an attractive alternative to conventional wires for wearable applications

  4. Highly stretchable wrinkled gold thin film wires

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Joshua, E-mail: joshuk7@uci.edu; Park, Sun-Jun; Nguyen, Thao [Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697 (United States); Chu, Michael [Department of Biomedical Engineering, University of California, Irvine, California 92697 (United States); Pegan, Jonathan D. [Department of Materials and Manufacturing Technology, University of California, Irvine, California 92697 (United States); Khine, Michelle, E-mail: mkhine@uci.edu [Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697 (United States); Department of Biomedical Engineering, University of California, Irvine, California 92697 (United States)

    2016-02-08

    With the growing prominence of wearable electronic technology, there is a need to improve the mechanical reliability of electronics for more demanding applications. Conductive wires represent a vital component present in all electronics. Unlike traditional planar and rigid electronics, these new wearable electrical components must conform to curvilinear surfaces, stretch with the body, and remain unobtrusive and low profile. In this paper, the piezoresistive response of shrink induced wrinkled gold thin films under strain demonstrates robust conductive performance in excess of 200% strain. Importantly, the wrinkled metallic thin films displayed negligible change in resistance of up to 100% strain. The wrinkled metallic wires exhibited consistent performance after repetitive strain. Importantly, these wrinkled thin films are inexpensive to fabricate and are compatible with roll to roll manufacturing processes. We propose that these wrinkled metal thin film wires are an attractive alternative to conventional wires for wearable applications.

  5. Electroless plating of thin gold films directly onto silicon nitride thin films and into micropores.

    Science.gov (United States)

    Whelan, Julie C; Karawdeniya, Buddini Iroshika; Bandara, Y M Nuwan D Y; Velleco, Brian D; Masterson, Caitlin M; Dwyer, Jason R

    2014-07-23

    A method to directly electrolessly plate silicon-rich silicon nitride with thin gold films was developed and characterized. Films with thicknesses coating planar, curved, and line-of-sight-obscured silicon nitride surfaces. PMID:24999923

  6. High temperature superconducting thin film microwave filters

    International Nuclear Information System (INIS)

    Low loss thin films of high temperature superconductors (HTSC) on MgO as well as LaAlO3 substrates has been successfully developed. This effort aims at the development of application oriented innovations, such as HTSC based passive microwave devices. As an initial attempt in developing microwave devices, we have designed, fabricated and tested HTSC microstrip resonators at X-band using YBCO thin films on LaAlO3 substrates

  7. Advances in CZTS thin films and nanostructured

    Science.gov (United States)

    Ali, N.; Ahmed, R.; Bakhtiar-Ul-Haq; Shaari, A.

    2015-06-01

    Already published data for the optical band gap (Eg) of thin films and nanostructured copper zinc tin sulphide (CZTS) have been reviewed and combined. The vacuum (physical) and non-vacuum (chemical) processes are focused in the study for band gap comparison. The results are accumulated for thin films and nanostructured in different tables. It is inferred from the re- view that the nanostructured material has plenty of worth by engineering the band gap for capturing the maximum photons from solar spectrum.

  8. Laser-annealing of thin semiconductor films

    OpenAIRE

    Boneberg, Johannes; Nedelcu, Johann; Bucher, Ernst; Leiderer, Paul

    1994-01-01

    Optical reflectivity and transmissivity measurements have been used to investigate the dynamics of melting and recrystallisation of thin films of Si and Ge after laser-annealing with a ns Nd:YAG-laser pulse. We report on temperature dependent changes of the reflectivity of the liquid phase above and below the melting point and on various nucleation and solidification scenarios in thin film, depending on the energy density of the amding laser.

  9. Characteristics and durability of fluoropolymer thin films

    OpenAIRE

    Cheneler, David; Bowen, James; Evans, Stephen D.; Górzny, Marcin; Adams, Michael J; Ward, Michael C.L.

    2011-01-01

    The use of plasma-polymerised fluoropolymer (CFxOy) thin films in the manufacture of microelectromechanical systems (MEMS) devices is well-established, being employed in the passivation step of the deep reactive ion etching (DRIE) process, for example. This paper presents an investigation of the effect of exposure to organic and aqueous liquid media on plasma polymerised CFxOy thin films. Atomic force microscopy (AFM), scanning electron microscopy (SEM), ellipsometry, X-ray photoelectron spec...

  10. Thin film description by wavelet coefficients statistics

    Czech Academy of Sciences Publication Activity Database

    Boldyš, Jiří; Hrach, R.

    2005-01-01

    Roč. 55, č. 1 (2005), s. 55-64. ISSN 0011-4626 Grant ostatní: GA UK(CZ) 173/2003 Institutional research plan: CEZ:AV0Z10750506 Keywords : thin films * wavelet transform * descriptors * histogram model Subject RIV: BD - Theory of Information Impact factor: 0.360, year: 2005 http://library.utia.cas.cz/separaty/2009/ZOI/boldys-thin film description by wavelet coefficients statistics .pdf

  11. Epitaxy, thin films and superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Jagd Christensen, Morten

    1997-05-01

    This report is the result of structural investigations of 3d transition metal superlattices consisting of Fe/V, Cr/Mn, V/Mn and Fe/Mn, and a structural and magnetic study of a series of Ho/Pr alloys. The work includes preparation and characterization of substrates as well as growth of thin films and Fe/V superlattices by molecular beam epitaxy, including in-situ characterization by reflection high energy electron diffraction and Auger electron spectroscopy. Structural characterization has been done by x-ray diffraction and neutron diffraction. The x-ray diffraction experiments have been performed on the rotating copper anode at Risoe, and at synchrotron facilities in Hamburg and Brookhaven, and the neutron scattering was done at the Danish research reactor DR3 at Risoe. In addition to longitudinal scans, giving information about the structural parameters in the modulation direction, non-specular scans were also performed. This type of scans gives information about in-plane orientation and lattice parameters. From the analysis, structural information is obtained about lattice parameters, epitaxial strain, coherence lengths and crystallographic orientation for the superlattice systems, except Fe/Mn superlattices, which could not be modelled. For the Ho/Pr alloys, x-ray magnetic scattering was performed, and the crystal and magnetic structure was investigated. (au) 14 tabs.; 58 ills., 96 refs.

  12. Studies in thin film flows

    CERN Document Server

    McKinley, I S

    2000-01-01

    the general case of non-zero capillary number numerically. Using the lubrication approximation to the Navier-Stokes equations we investigate the evolution and stability of a thin film of incompressible Newtonian fluid on a planar substrate subjected to a jet of air blowing normally to the substrate. For the simple model of the air jet we adopt, the initially axisymmetric problems we study are identical to those of a drop spreading on a turntable rotating at constant angular velocity (the simplest model for spin coating). We consider both drops without a dry patch (referred to as 'non-annular') and drops with a dry patch at their centre (referred to as 'annular'). First, both symmetric two-dimensional and axisymmetric three-dimensional drops are considered in the quasi-static limit of small capillary number. The evolution of both non-annular and annular drops and the stability of equilibrium solutions to small perturbations with zero wavenumber are determined. Using a specially developed finite-difference code...

  13. Epitaxy, thin films and superlattices

    International Nuclear Information System (INIS)

    This report is the result of structural investigations of 3d transition metal superlattices consisting of Fe/V, Cr/Mn, V/Mn and Fe/Mn, and a structural and magnetic study of a series of Ho/Pr alloys. The work includes preparation and characterization of substrates as well as growth of thin films and Fe/V superlattices by molecular beam epitaxy, including in-situ characterization by reflection high energy electron diffraction and Auger electron spectroscopy. Structural characterization has been done by x-ray diffraction and neutron diffraction. The x-ray diffraction experiments have been performed on the rotating copper anode at Risoe, and at synchrotron facilities in Hamburg and Brookhaven, and the neutron scattering was done at the Danish research reactor DR3 at Risoe. In addition to longitudinal scans, giving information about the structural parameters in the modulation direction, non-specular scans were also performed. This type of scans gives information about in-plane orientation and lattice parameters. From the analysis, structural information is obtained about lattice parameters, epitaxial strain, coherence lengths and crystallographic orientation for the superlattice systems, except Fe/Mn superlattices, which could not be modelled. For the Ho/Pr alloys, x-ray magnetic scattering was performed, and the crystal and magnetic structure was investigated. (au)

  14. Superconducting thin-film gradiometer

    International Nuclear Information System (INIS)

    We describe the design, fabrication, and performance of planar thin-film dc SQUID's and planar gradiometers in which a dc SQUID is incorporated as a null detector. Each gradiometer was fabricated on a planar substrate and measured an off-diagonal component of changes in the magnetic field gradient. The gradiometer with the highest sensitivity had 127 x 33-mm loops that could be connected in parallel or in series: The sensitivities were 2.1 x 10-13 and 3.7 x 10-13 T m-1 Hz/sup -1/2/, respectively. The intrinsic balance of the gradiometers was about 100 ppm for fields parallel to their plane, and a balance of about 1 ppm could be achieved for fields perpendicular to their plane. When the series-loop gradiometer was rotated through 3600 in the earth's field, the output returned to its initial value to within an amount corresponding to a balance of 1 ppm. Possible improvements in sensitivity are discussed

  15. Microstructural evolution of tungsten oxide thin films

    Science.gov (United States)

    Hembram, K. P. S. S.; Thomas, Rajesh; Rao, G. Mohan

    2009-10-01

    Tungsten oxide thin films are of great interest due to their promising applications in various optoelectronic thin film devices. We have investigated the microstructural evolution of tungsten oxide thin films grown by DC magnetron sputtering on silicon substrate. The structural characterization and surface morphology were carried out using X-ray diffraction and Scanning Electron Microscopy (SEM). The as deposited films were amorphous, where as, the films annealed above 400 °C were crystalline. In order to explain the microstructural changes due to annealing, we have proposed a "instability wheel" model for the evolution of the microstructure. This model explains the transformation of mater into various geometries within them selves, followed by external perturbation.

  16. Microstructural evolution of tungsten oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hembram, K.P.S.S., E-mail: hembram@isu.iisc.ernet.in [Department of Instrumentation, Indian Institute of Science, Bangalore - 560 012 (India); Theoretical Science Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore - 560064 (India); Thomas, Rajesh; Rao, G. Mohan [Department of Instrumentation, Indian Institute of Science, Bangalore - 560 012 (India)

    2009-10-30

    Tungsten oxide thin films are of great interest due to their promising applications in various optoelectronic thin film devices. We have investigated the microstructural evolution of tungsten oxide thin films grown by DC magnetron sputtering on silicon substrate. The structural characterization and surface morphology were carried out using X-ray diffraction and Scanning Electron Microscopy (SEM). The as deposited films were amorphous, where as, the films annealed above 400 deg. were crystalline. In order to explain the microstructural changes due to annealing, we have proposed a 'instability wheel' model for the evolution of the microstructure. This model explains the transformation of mater into various geometries within them selves, followed by external perturbation.

  17. Thin-film crystalline silicon solar cells

    CERN Document Server

    Brendel, Rolf

    2011-01-01

    This introduction to the physics of silicon solar cells focuses on thin cells, while reviewing and discussing the current status of the important technology. An analysis of the spectral quantum efficiency of thin solar cells is given as well as a full set of analytical models. This is the first comprehensive treatment of light trapping techniques for the enhancement of the optical absorption in thin silicon films.

  18. Post deposition purification of PTCDA thin films

    International Nuclear Information System (INIS)

    The decomposition of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) molecules during evaporation of unpurified raw material in ultra high vacuum was studied. The fragments were identified by mass spectrometry and the influence of these fragments and further contaminations of the raw material on the electronic structure of PTCDA thin films was measured by photoemission spectroscopy. Annealing of contaminated PTCDA films was tested as cheap and easy to perform method for (partial) post deposition purification of the contaminated films

  19. Polymer surfaces, interfaces and thin films

    International Nuclear Information System (INIS)

    Neutron reflectometry can be used in various ways to investigate surfaces, interfaces and thin films of polymers. Its potential comes mostly from the possibilities offered by selective deuteration, where a particular component can be made visible with respect to its activity at the interface. In addition the depth resolution is much better than with most other direct techniques, and details of the profiles may be resolved. Several examples will be discussed including the segment diffusion at the interface between two polymer films, the determination of the narrow interfaces between incompatible polymer blends and the development of order in thin diblock copolymer films. (author) 10 figs., 2 tabs., 38 refs

  20. Thin-film Rechargeable Lithium Batteries

    Science.gov (United States)

    Dudney, N. J.; Bates, J. B.; Lubben, D.

    1995-06-01

    Thin film rechargeable lithium batteries using ceramic electrolyte and cathode materials have been fabricated by physical deposition techniques. The lithium phosphorous oxynitride electrolyte has exceptional electrochemical stability and a good lithium conductivity. The lithium insertion reaction of several different intercalation materials, amorphous V{sub 2}O{sub 5}, amorphous LiMn{sub 2}O{sub 4}, and crystalline LiMn{sub 2}O{sub 4} films, have been investigated using the completed cathode/electrolyte/lithium thin film battery.

  1. Polymer surfaces, interfaces and thin films

    Energy Technology Data Exchange (ETDEWEB)

    Stamm, M. [Max-Planck-Institut fuer Polymerforschung, Mainz (Germany)

    1996-11-01

    Neutron reflectometry can be used in various ways to investigate surfaces, interfaces and thin films of polymers. Its potential comes mostly from the possibilities offered by selective deuteration, where a particular component can be made visible with respect to its activity at the interface. In addition the depth resolution is much better than with most other direct techniques, and details of the profiles may be resolved. Several examples will be discussed including the segment diffusion at the interface between two polymer films, the determination of the narrow interfaces between incompatible polymer blends and the development of order in thin diblock copolymer films. (author) 10 figs., 2 tabs., 38 refs.

  2. Synthesis and characterization of Bi{sub 1−x}Nd{sub x}FeO{sub 3} thin films deposited using a high throughput physical vapour deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Darby, M.S.B., E-mail: darbymsb@gmail.com [Department of Materials, Science and Engineering, University of Sheffield, Sheffield, S1 3JD (United Kingdom); Karpinsky, D.V. [Complexo de Laboratórios Tecnológicos, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Pokorny, J. [Department of Materials, Science and Engineering, University of Sheffield, Sheffield, S1 3JD (United Kingdom); Institute of Physics, Academy of Sciences of the Czech Republic, 182 21 Prague (Czech Republic); Guerin, S. [Ilika Technologies Limited, Kenneth Dibben House, Enterprise Road, University of Southampton Science Park, Chilworth, Southampton, SO16 7NS (United Kingdom); Kholkin, A.L. [Complexo de Laboratórios Tecnológicos, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Miao, S. [Department of Materials, Science and Engineering, University of Sheffield, Sheffield, S1 3JD (United Kingdom); Hayden, B.E. [Ilika Technologies Limited, Kenneth Dibben House, Enterprise Road, University of Southampton Science Park, Chilworth, Southampton, SO16 7NS (United Kingdom); Reaney, I.M. [Department of Materials, Science and Engineering, University of Sheffield, Sheffield, S1 3JD (United Kingdom)

    2013-03-01

    The high throughput synthesis of BiFeO{sub 3} and rare earth doped BiFeO{sub 3} films using a modified molecular beam epitaxy technique is reported. Optimum conditions for deposition have been established and compositionally graded Bi{sub (1−x)}Nd{sub x}FeO{sub 3} (x = 0.08 to 0.24) thin films have been fabricated on platinised silicon substrate (Si/SiO{sub 2}/TiO{sub 2}/Pt) with the aim of finding the optimum Nd dopant concentrations for enhanced piezoelectric properties. For x < 0.12, the structure and symmetry were identical to that of the R3c BiFeO{sub 3} end member. For x > 0.20, the structure and symmetry were consistent with the NdFeO{sub 3} end member (Pnma). For compositions 0.12 < x < 0.2, a gradual transition from R3c to Pnma was observed via a mixed phase region but no compositional interval could be unambiguously identified in which the intermediate PbZrO{sub 3}-like structure, reported by Karimi et al. (2009) [6], existed as a single phase. Piezoresponse force microscopy remanent hysteresis measurements of the film revealed a statistical increase in the piezoelectric response at x ≈ 0.11 within the R3c region adjacent to the mixed phase field. - Highlights: ► High throughput synthesis and characterization of BiFeO3 and Nd-doped BiFeO3 films ► The piezoelectric properties of compositionally graded bismuth ferrite are studied. ► The structure and phase assemblage of Nd-doped bismuth ferrite have been studied.

  3. Thin Ice Films at Mineral Surfaces.

    Science.gov (United States)

    Yeşilbaş, Merve; Boily, Jean-François

    2016-07-21

    Ice films formed at mineral surfaces are of widespread occurrence in nature and are involved in numerous atmospheric and terrestrial processes. In this study, we studied thin ice films at surfaces of 19 synthetic and natural mineral samples of varied structure and composition. These thin films were formed by sublimation of thicker hexagonal ice overlayers mostly produced by freezing wet pastes of mineral particles at -10 and -50 °C. Vibration spectroscopy revealed that thin ice films contained smaller populations of strongly hydrogen-bonded water molecules than in hexagonal ice and liquid water. Thin ice films at the surfaces of the majority of minerals considered in this work [i.e., metal (oxy)(hydr)oxides, phyllosilicates, silicates, volcanic ash, Arizona Test Dust] produced intense O-H stretching bands at ∼3400 cm(-1), attenuated bands at ∼3200 cm(-1), and liquid-water-like bending band at ∼1640 cm(-1) irrespective of structure and composition. Illite, a nonexpandable phyllosilicate, is the only mineral that stabilized a form of ice that was strongly resilient to sublimation in temperatures as low as -50 °C. As mineral-bound thin ice films are the substrates upon which ice grows from water vapor or aqueous solutions, this study provides new constraints from which their natural occurrences can be understood. PMID:27377606

  4. Carrier lifetimes in thin-film photovoltaics

    Science.gov (United States)

    Baek, Dohyun

    2015-09-01

    The carrier lifetimes in thin-film solar cells are reviewed and discussed. Shockley-Read-Hall recombination is dominant at low carrier density, Auger recombination is dominant under a high injection condition and high carrier density, and surface recombination is dominant under any conditions. Because the surface photovoltage technique is insensitive to the surface condition, it is useful for bulk lifetime measurements. The photoconductance decay technique measures the effective recombination lifetime. The time-resolved photoluminescence technique is very useful for measuring thin-film semiconductor or solar-cell materials lifetime, because the sample is thin, other techniques are not suitable for measuring the lifetime. Many papers have provided time-resolved photoluminescence (TRPL) lifetimes for copper-indium-gallium-selenide (CIGS) and CdTe thin-film solar cell. The TRPL lifetime strongly depends on open-circuit voltage and conversion efficiency; however, the TRPL life time is insensitive to the short-circuit current.

  5. Formation and Characterization of Transversely Modulated Nanostructures in Metallic Thin Films using Epitaxial Control

    Science.gov (United States)

    Boyerinas, Brad Michael

    This thesis describes a fundamental investigation into the formation, characterization, and modeling of epitaxially-controlled self-assembly at the nanoscale. The presence of coherent nanophases and the clamping effect from an epitaxial substrate enables the formation of transversely modulated nanostructures (TMNS) resulting in improved functionality, which was previously observed through increased piezoelectric response in BiFeO3. The ability to fabricate high quality epitaxial films presents opportunity to investigate coherent phase decomposition in other material systems with multifunctional response. The research herein aims to extend the concept of nanoscale self assembly in metallic systems, including Ag-Si and Pd-PdH. First, the effect of annealing a Ag-Si couple was examined, and ordered, nanoscale Ag crystallites were observed along the interface with the epitaxial Si wafer. It is demonstrated that Ag foil can be used in place of doped Ag paste (commonly used in solar cell metallization) to achieve TMNS at the interface. It was proved that annealing the Ag-Si couple in air is necessary for the self-assembly reaction to take place, as doing so prevents bulk diffusion and eutectic melting. Electron backscatter diffraction was used to verify the epitaxial relation between the Ag nanostructures and Si crystal. A method to fabricate ordered, nanoscale PdH precipitates in epitaxial Pd thin films via high temperate gas phase hydrogenation was established. Epitaxial Pd films were deposited via e-beam deposition and a V buffer layer was necessary to induce epitaxy. This novel self-assembled nanostructure may enable hysteresis-less absorption and desorption, thus improving functionality with regard to hydrogen sensing and storage. The epitaxial Pd film was characterized before and after hydrogenation with x-ray diffraction and atomic force microscopy to determine composition and nanostructure of the film. A thermodynamic model was developed to demonstrate the

  6. Nanostructured thin films as functional coatings

    Energy Technology Data Exchange (ETDEWEB)

    Lazar, Manoj A; Tadvani, Jalil K; Tung, Wing Sze; Lopez, Lorena; Daoud, Walid A, E-mail: Walid.Daoud@sci.monash.edu.au [School of Applied Sciences and Engineering, Monash University, Churchill, VIC 3842 (Australia)

    2010-06-15

    Nanostructured thin films is one of the highly exploiting research areas particularly in applications such as photovoltaics, photocatalysis and sensor technologies. Highly tuned thin films, in terms of thickness, crystallinity, porosity and optical properties, can be fabricated on different substrates using the sol-gel method, chemical solution deposition (CSD), electrochemical etching, along with other conventional methods such as chemical vapour deposition (CVD) and physical vapour deposition (PVD). The above mentioned properties of these films are usually characterised using surface analysis techniques such as XRD, SEM, TEM, AFM, ellipsometry, electrochemistry, SAXS, reflectance spectroscopy, STM, XPS, SIMS, ESCA, X-ray topography and DOSY-NMR. This article presents a short review of the preparation and characterisation of thin films of nanocrystalline titanium dioxide and modified silicon as well as their application in solar cells, water treatment, water splitting, self cleaning fabrics, sensors, optoelectronic devices and lab on chip systems.

  7. Nanostructured thin films as functional coatings

    International Nuclear Information System (INIS)

    Nanostructured thin films is one of the highly exploiting research areas particularly in applications such as photovoltaics, photocatalysis and sensor technologies. Highly tuned thin films, in terms of thickness, crystallinity, porosity and optical properties, can be fabricated on different substrates using the sol-gel method, chemical solution deposition (CSD), electrochemical etching, along with other conventional methods such as chemical vapour deposition (CVD) and physical vapour deposition (PVD). The above mentioned properties of these films are usually characterised using surface analysis techniques such as XRD, SEM, TEM, AFM, ellipsometry, electrochemistry, SAXS, reflectance spectroscopy, STM, XPS, SIMS, ESCA, X-ray topography and DOSY-NMR. This article presents a short review of the preparation and characterisation of thin films of nanocrystalline titanium dioxide and modified silicon as well as their application in solar cells, water treatment, water splitting, self cleaning fabrics, sensors, optoelectronic devices and lab on chip systems.

  8. Niobium Thin Film Characterization for Thin Film Technology Used in Superconducting Radiofrequency Cavities

    Science.gov (United States)

    Dai, Yishu; Valente-Feliciano, Anne-Marie

    2015-10-01

    Superconducting RadioFrequency (SRF) penetrates about 40-100 nm of the top surface, making thin film technology possible in producing superconducting cavities. Thin film is based on the deposition of a thin Nb layer on top of a good thermal conducting material such as Al or Cu. Thin film allows for better control of the surface and has negligible response to the Earth's magnetic field, eliminating the need for magnetic shielding of the cavities. Thin film superconductivity depends heavily on coating process conditions, involving controllable parameters such as crystal plane orientation, coating temperature, and ion energy. MgO and Al2O3 substrates are used because they offer very smooth surfaces, ideal for studying film growth. Atomic Force Microscopy is used to characterize surface's morphology. It is evident that a lower nucleation energy and a long coating time increases the film quality in the r-plane sapphire crystal orientation. The quality of the film increases with thickness. Nb films coated on r-plane, grow along the (001) plane and yield a much higher RRR compared to the films grown on a- and c-planes. This information allows for further improvement on the research process for thin film technology used in superconducting cavities for the particle accelerators. National Science Foundation, Department of Energy, Jefferson Lab, Old Dominion University.

  9. Electrochemical Analysis of Conducting Polymer Thin Films

    Directory of Open Access Journals (Sweden)

    Bin Wang

    2010-04-01

    Full Text Available Polyelectrolyte multilayers built via the layer-by-layer (LbL method has been one of the most promising systems in the field of materials science. Layered structures can be constructed by the adsorption of various polyelectrolyte species onto the surface of a solid or liquid material by means of electrostatic interaction. The thickness of the adsorbed layers can be tuned precisely in the nanometer range. Stable, semiconducting thin films are interesting research subjects. We use a conducting polymer, poly(p-phenylene vinylene (PPV, in the preparation of a stable thin film via the LbL method. Cyclic voltammetry and electrochemical impedance spectroscopy have been used to characterize the ionic conductivity of the PPV multilayer films. The ionic conductivity of the films has been found to be dependent on the polymerization temperature. The film conductivity can be fitted to a modified Randle’s circuit. The circuit equivalent calculations are performed to provide the diffusion coefficient values.

  10. Hydrogen behavior in nanocrystalline titanium thin films

    International Nuclear Information System (INIS)

    Nanocrystalline titanium films of different thicknesses, sputtered on sapphire substrates, were charged electrochemically with hydrogen. Hydrogen absorption and the thermodynamics of the nanocrystalline Ti-H thin film system were studied using electromotive force (EMF) measurements. The phase boundaries obtained from the EMF-pressure-concentration curves were confirmed by X-ray diffraction, complemented by in situ stress measurements during hydrogen charging. The change in the stress increase with hydrogen concentration was found to be in good agreement with the obtained phase boundaries. In comparison to bulk Ti-H system, considerable changes, such as shifted phase boundaries, and narrowed and sloped miscibility gaps, were observed in Ti-H thin films. These changes vary among the films of different crystalline orientation and are attributed to both microstructural effects and stress contributions. The influence of the initial crystallographic growth orientation of Ti films on the measured thermodynamic isotherms, phase transitions and stress development is discussed in detail.

  11. Thermal conductivity of nanoscale thin nickel films

    Institute of Scientific and Technical Information of China (English)

    YUAN Shiping; JIANG Peixue

    2005-01-01

    The inhomogeneous non-equilibrium molecular dynamics (NEMD) scheme is applied to model phonon heat conduction in thin nickel films. The electronic contribution to the thermal conductivity of the film is deduced from the electrical conductivity through the use of the Wiedemann-Franz law. At the average temperature of T = 300 K, which is lower than the Debye temperature ()D = 450 K,the results show that in a film thickness range of about 1-11 nm, the calculated cross-plane thermal conductivity decreases almost linearly with the decreasing film thickness, exhibiting a remarkable reduction compared with the bulk value. The electrical and thermal conductivities are anisotropic in thin nickel films for the thickness under about 10 nm. The phonon mean free path is estimated and the size effect on the thermal conductivity is attributed to the reduction of the phonon mean free path according to the kinetic theory.

  12. Critical behavior of ferromagnetic Ising thin films

    International Nuclear Information System (INIS)

    In the present work, we study the magnetic properties and critical behavior of simple cubic ferromagnetic thin films. We simulate LxLxd films with semifree boundary conditions on the basis of the Monte Carlo method and the Ising model with nearest neighbor interactions. A Metropolis dynamics was implemented to carry out the energy minimization process. For different film thickness, in the nanometer range, we compute the temperature dependence of the magnetization, the magnetic susceptibility and the fourth order Binder's cumulant. Bulk and surface contributions of these quantities are computed in a differentiated fashion. Additionally, according to finite size scaling theory, we estimate the critical exponents for the correlation length, magnetic susceptibility, and magnetization. Results reveal a strong dependence of critical temperature and critical exponents on the film thickness. The obtained critical exponents are finally compared to those reported in literature for thin films

  13. Thermal conductivities of thin, sputtered optical films

    International Nuclear Information System (INIS)

    The normal component of thin-film thermal conductivity has been measured for the first time, to the best of our knowledge, for several advanced sputtered optical materials. Included are data for single layers of boron nitride, silicon aluminum nitride, silicon aluminum oxynitride, silicon carbide, and for dielectric-enhanced metal reflectors of the form Al(SiO2/Si3N4)n and Al(Al2O3/AlN)n. Sputtered films of more conventional materials such as SiO2, Al2O3, Ta2O5, Ti, and Si have also been measured. The data show that thin-film thermal conductivities are typically 10 to 100 times lower than conductivities for the same materials in bulk form. Structural disorder in the amorphous or fine-grained films appears to account for most of the conductivity difference. Conclusive evidence for a film--substrate interface contribution is presented

  14. Surface morphology of thin films polyoxadiazoles

    Directory of Open Access Journals (Sweden)

    J. Weszka

    2011-12-01

    Full Text Available urpose: The purpose of this paper was to analyse the surface morphology of thin films polyoxadiazoles. Design/methodology/approach: SSix different polymers which belong to the group of polyoxadiazoles were dissolved in the solvent NMP. Each of these polymer was deposited on a glass substrate and a spin coating method was applied with a spin speed of 1000, 2000 and 3000 rev/min. Changes in surface topography and roughness were observed. An atomic force microscope AFM Park System has been used. Photos have been taken in noncontact mode while observing an area of 10 x 10 microns.Findings: The analysis of images has confirmed that the quality of thin films depends upon the used polymers. It was also observed that the parameters of the spin coating method have significant effect on the morphology and the surface roughness. The speed of the spin has got a strong impact on the topography of the thin films obtained.Research limitations/implications: The morphology of polyoxadiazoles thin films has been described. This paper include description how the spin speed influences the morphology of polymer thin films. In order to use a polymer thin film in photovoltaics or optoelectronics it must have a uniform thickness and a low surface roughness. Further research, in which the optical properties of thin films are investigated, is strongly recommended.Practical implications: Conductive polymers may find applications in photovoltaics or optoelectronics. It is important to study this group of material engineering and to find a new use for them. Materials from which thin films are made of will have an impact on the properties and characteristics of electronics devices in which they are be applied.Originality/value: The value of this paper is defining the optimal parameters of spin-coating technology for six polyoxadiazoles. The results allow the choosing optimal parameters of the deposition process. Spin coating is a very good method to obtain thin films which

  15. Thin Films in the Photovoltaic Industry

    International Nuclear Information System (INIS)

    In the past years, the yearly world market growth rate for Photovoltaics was an average of more than 40%, which makes it one of the fastest growing industries at present. Business analysts predict the market volume to increase to 40 billion euros in 2010 and expect rising profit margins and lower prices for consumers at the same time. Today PV is still dominated by wafer based Crystalline Silicon Technology as the 'working horse' in the global market, but thin films are gaining market shares. For 2007 around 12% are expected. The current silicon shortage and high demand has kept prices higher than anticipated from the learning curve experience and has widened the windows of opportunities for thin film solar modules. Current production capacity estimates for thin films vary between 3 and 6 GW in 2010, representing a 20% market share for these technologies. Despite the higher growth rates for thin film technologies compared with the industry average, Thin Film Photovoltaic Technologies are still facing a number of challenges to maintain this growth and increase market shares. The four main topics which were discussed during the workshop were: Potential for cost reduction; Standardization; Recycling; Performance over the lifetime.

  16. ANTIFERROMAGNETIC TO PARAMAGNETIC PHASE TRANSITIONS IN BISMUTH FERRITE (BiFeO3 CERAMICS BY SOLID STATE REACTION

    Directory of Open Access Journals (Sweden)

    Chandrashekhar P. Bhole

    2012-07-01

    Full Text Available This paper describes the synthesis of multiferroic BiFeO3 ceramics was prepared by solid state reaction and high energy ball milling method. The structural studies was carried out by using an X-ray diffraction pattern and demonstrated that the BiFeO3 ceramic crystallizes in a rhombhohedral perovskite phase. The ferroelectric hystersis loop measured at room temperature demonstrates a lossy loop with unsaturated behavior and symbolize a partial reversal of polarization. A dielectric constant with temperature measurement for BiFeO3 ceramic represents an anomaly around 350°C for all frequencies and intimately associated with antiferromagnetic to paramagnetic phase transition (TN of BiFeO3.

  17. Ion beam-based characterization of multicomponent oxide thin films and thin film layered structures

    International Nuclear Information System (INIS)

    Fabrication of thin film layered structures of multi-component materials such as high temperature superconductors, ferroelectric and electro-optic materials, and alloy semiconductors, and the development of hybrid materials requires understanding of film growth and interface properties. For High Temperature Superconductors, the superconducting coherence length is extremely short (5--15 Angstrom), and fabrication of reliable devices will require control of film properties at extremely sharp interfaces; it will be necessary to verify the integrity of thin layers and layered structure devices over thicknesses comparable to the atomic layer spacing. Analytical techniques which probe the first 1--2 atomic layers are therefore necessary for in-situ characterization of relevant thin film growth processes. However, most surface-analytical techniques are sensitive to a region within 10--40 Angstrom of the surface and are physically incompatible with thin film deposition and are typically restricted to ultra high vacuum conditions. A review of ion beam-based analytical methods for the characterization of thin film and multi-layered thin film structures incorporating layers of multicomponent oxides is presented. Particular attention will be paid to the use of time-of-flight techniques based on the use of 1- 15 key ion beams which show potential for use as nondestructive, real-time, in-situ surface diagnostics for the growth of multicomponent metal and metal oxide thin films

  18. Measuring thin films by transmission spectroscopy

    International Nuclear Information System (INIS)

    Full text: The refractive index, extinction coefficient and thickness of thin dielectric films are important parameters for device manufacturers and experimenters. We have developed a method which allows these values to be determined from a single transmission spectrum of the film as deposited on a known substrate. The technique exploits the interference fringes seen in such a transmission spectrum to establish envelope functions of the turning points in the spectrum. From these envelope functions the refractive index and extinction coefficient of the film is determined at each turning point. Consequently we can determine the film's thickness with a single measurement step. Copyright (2005) Australian Institute of Physics

  19. Thermal conductivity of dielectric thin films

    International Nuclear Information System (INIS)

    A direct reading thermal comparator has been used to measure the thermal conductivity of dielectric thin film coatings. In the past, the thermal comparator has been used extensively to measure the thermal conductivity of bulk solids, liquids, and gases. The technique has been extended to thin film materials by making experimental improvements and by the application of an analytical heat flow model. Our technique also allows an estimation of the thermal resistance of the film/substrate interface which is shown to depend on the method of film deposition. The thermal conductivity of most thin films was found to be several orders of magnitude lower than that of the material in bulk form. This difference is attributed to structural disorder of materials deposited in thin film form. The experimentation to date has centered primarily on optical coating materials. These coatings, used to enhance the optical properties of components such as lenses and mirrors, are damaged by thermal loads applied in high-power laser applications. It has been widely postulated that there may be a correlation between the thermal conductivity and the damage threshold of these materials. 31 refs., 11 figs., 8 tabs

  20. Organic thin films and surfaces directions for the nineties

    CERN Document Server

    Ulman, Abraham

    1995-01-01

    Physics of Thin Films has been one of the longest running continuing series in thin film science consisting of 20 volumes since 1963. The series contains some of the highest quality studies of the properties ofvarious thin films materials and systems.In order to be able to reflect the development of todays science and to cover all modern aspects of thin films, the series, beginning with Volume 20, will move beyond the basic physics of thin films. It will address the most important aspects of both inorganic and organic thin films, in both their theoretical as well as technological aspects. Ther

  1. Control of crystal phase and morphology in hydrothermal synthesis of BiFeO3 crystal

    Science.gov (United States)

    Xu, Xuqing; Xu, Qianrui; Huang, Yajun; Hu, Xiuxiu; Huang, Yuqing; Wang, Gaoyu; Hu, Xiaolin; Zhuang, Naifeng

    2016-03-01

    Bismuth ferrite crystal is synthesized by hydrothermal method. The effect of hydrothermal temperature, KOH concentration, supersaturation, cooling rate, and compactedness on the crystal phase and the morphology of product were investigated. The results indicated that BiFeO3 microcrystalline with good quality could been synthesized at 140-240 °C with KOH concentration of 4-14 mol L-1. In addition, it is favorable for improving the crystal quality to reduce the supersaturation and decrease the cooling rate. With the increasing of the compactedness, surface holes and cracks of the as-grown crystals would be reduced. The optimization of hydrothermal condition provides guidance to grow BiFeO3 crystal with a large size and high quality for practical application.

  2. BiFeO3 nanocrystals for bio-imaging based on nonlinear optical harmonic generation

    CERN Document Server

    Schwung, Sebastian; Clarke, Gareth; Joulaud, Cécile; Magouroux, Thibaud; Staedler, Davide; Passemard, Solène; Jüstel, Thomas; Badie, Laurent; Galez, Christine; Wolf, Jean Pierre; Volkov, Yuri; Prina-Mello, Adriele; Gerber-Lemaire, Sandrine; Rytz, Daniel; Mugnier, Yannick; Bonacina, Luigi; Dantec, Ronan Le

    2014-01-01

    Second Harmonic Generation (SHG) from BiFeO3 nanocrystals is investigated for the first time to determine their potential as biomarkers for multiphoton imaging. Nanocrystals are produced by an auto-combustion method with TRIS as a fuel. Stable colloidal suspensions with mean particle diameters in the range 100-120 nm are then obtained after wet-milling and sonication steps. SHG properties are determined using two complementary experimental techniques, Hyper Rayleigh Scattering and nonlinear polarization microscopy. BiFeO3 shows a very high second harmonic efficiency with an averaged coefficient of 79+-12 pm/V. From the nonlinear polarization response of individual nanocrystals, relative values of the independent dij coefficients are also determined and compared with recent theoretical and experimental studies. Additionally, the particles show a moderate magnetic response, which is attributed to gamma-Fe2O3 impurities. A combination of high nonlinear optical efficiency and magnetic response within the same pa...

  3. Pressure-induced phase transitions of multiferroic BiFeO3

    International Nuclear Information System (INIS)

    Pressure-induced phase transitions of multiferroic BiFeO3 have been investigated using synchrotron radiation X-ray diffraction with diamond anvil cell technique at room temperature. Present experimental data clearly show that rhombohedral (R3c) phase of BiFeO3 first transforms to monoclinic (C2/m) phase at 7 GPa, then to orthorhombic (Pnma) phase at 11 GPa, which is consistent with recent theoretical ab initio calculation. However, we observe another peak at 2θ=7° in the pressure range of 5-7 GPa that has not been reported previously. Further analysis reveals that this reflection peak is attributed to the orthorhombic (Pbam) phase, indicating the coexistence of monoclinic phase with orthorhombic phase in low pressure range. (authors)

  4. Crystallization of zirconia based thin films.

    Science.gov (United States)

    Stender, D; Frison, R; Conder, K; Rupp, J L M; Scherrer, B; Martynczuk, J M; Gauckler, L J; Schneider, C W; Lippert, T; Wokaun, A

    2015-07-28

    The crystallization kinetics of amorphous 3 and 8 mol% yttria stabilized zirconia (3YSZ and 8YSZ) thin films grown by pulsed laser deposition (PLD), spray pyrolysis and dc-magnetron sputtering are explored. The deposited films were heat treated up to 1000 °C ex situ and in situ in an X-ray diffractometer. A minimum temperature of 275 °C was determined at which as-deposited amorphous PLD grown 3YSZ films fully crystallize within five hours. Above 325 °C these films transform nearly instantaneously with a high degree of micro-strain when crystallized below 500 °C. In these films the t'' phase crystallizes which transforms at T > 600 °C to the t' phase upon relaxation of the micro-strain. Furthermore, the crystallization of 8YSZ thin films grown by PLD, spray pyrolysis and dc-sputtering are characterized by in situ XRD measurements. At a constant heating rate of 2.4 K min(-1) crystallization is accomplished after reaching 800 °C, while PLD grown thin films were completely crystallized already at ca. 300 °C. PMID:26119755

  5. Enhanced magnetoelectric properties of BiFeO3 on formation of BiFeO3/SrFe12O19 nanocomposites

    Science.gov (United States)

    Das, Anusree; Chatterjee, Souvik; Bandyopadhyay, Sudipta; Das, Dipankar

    2016-06-01

    Nanocomposites (NCs) comprising (1-x) BiFeO3 (BFO) and x SrFe12O19 (SRF) (x = 0.1, 0.2, 0.3, and 0.4) have been prepared by a sol-gel route. Presence of pure phases of both BiFeO3 (BFO) and SrFe12O19 (SRF) in the NCs for x = 0.3 and 0.4 has been confirmed by Rietveld analysis of XRD data though a minor impurity phase is observed in the case of x = 0.1 and 0.2 NCs. Transmission electron micrographs of the NCs show that particles are mostly spherical with average size of 30 nm. M-H measurements at 300 and 10 K indicate predominantly ferrimagnetic behavior of all the NCs with an increasing trend of saturation magnetization values with increasing content of SRF. Dielectric constant (ɛr) of the NCs at room temperature shows a dispersive behavior with frequency and attains a constant value at higher frequency. ɛr - T measurements reveal an increasing trend of dielectric constant of the NCs with increasing temperature and show an anomaly around the antiferromagnetic transition temperature of BFO, which indicates magnetoelectric coupling in the NCs. The variation of capacitance in the presence of magnetic field confirms the enhancement of magnetoelectric effect in the NCs. 57Fe Mössbauer spectroscopy results indicate the presence of only Fe3+ ions in usual crystallographic sites of BFO and SRF.

  6. Solid surfaces, interfaces and thin films

    CERN Document Server

    Lüth, Hans

    2015-01-01

    This book emphasises both experimental and theoretical aspects of surface, interface and thin-film physics. As in previous editions the preparation of surfaces and thin films, their atomic and morphological structure, their vibronic and electronic properties as well as fundamentals of adsorption are treated. Because of their importance in modern information technology and nanostructure research, particular emphasis is paid to electronic surface and interface states, semiconductor space charge layers and heterostructures. A special chapter of the book is devoted to collective phenomena at interfaces and in thin films such as superconductivity and magnetism. The latter topic includes the meanwhile important issues giant magnetoresistance and spin-transfer torque mechanism, both effects being of high interest in information technology. In this new edition, for the first time, the effect of spin-orbit coupling on surface states is treated. In this context the class of the recently detected topological insulators,...

  7. Method for synthesizing thin film electrodes

    Science.gov (United States)

    Boyle, Timothy J.

    2007-03-13

    A method for making a thin-film electrode, either an anode or a cathode, by preparing a precursor solution using an alkoxide reactant, depositing multiple thin film layers with each layer approximately 500 1000 .ANG. in thickness, and heating the layers to above 600.degree. C. to achieve a material with electrochemical properties suitable for use in a thin film battery. The preparation of the anode precursor solution uses Sn(OCH.sub.2C(CH.sub.3).sub.3).sub.2 dissolved in a solvent in the presence of HO.sub.2CCH.sub.3 and the cathode precursor solution is formed by dissolving a mixture of (Li(OCH.sub.2C(CH.sub.3).sub.3)).sub.8 and Co(O.sub.2CCH.sub.3).H.sub.2O in at least one polar solvent.

  8. Thin Film Photovoltaic/Thermal Solar Panels

    Institute of Scientific and Technical Information of China (English)

    David JOHNSTON

    2008-01-01

    A solar panel is described.in which thin films of semiconductor are deposited onto a metal substrate.The semiconductor-metal combination forms a thin film photovoltaic cell,and also acts as a reflector,absorber tandem, which acts as a solar selective surface,thus enhancing the solar thermal performance of the collector plate.The use of thin films reduces the distance heat is required to flow from the absorbing surface to the metal plate and heat exchange conduits.Computer modelling demonstrated that,by suitable choice of materials,photovohaic efficiency call be maintained,with thermal performance slishtly reduced,compared to that for thermal-only panels.By grading the absorber layer-to reduce the band gap in the lower region-the thermal performance can be improved,approaching that for a thermal-only solar panel.

  9. Thin-film solar cells. Duennschichtsolarzellen

    Energy Technology Data Exchange (ETDEWEB)

    Bloss, W.H.; Pfisterer, F.; Schock, H.W. (Stuttgart Univ. (Germany, F.R.). Inst. fuer Physikalische Elektronik)

    1990-01-01

    The authors present the state of the art in research and development, technology, production and marketing, and of the prospects of thin-film solar cells. Thin-film solar cells most used at present are based on amorphous silicon and on the compound semiconductors CuInSe{sub 2} and CdTe. Efficiencies in excess 12% have been achieved (14.1% with CuInSe{sub 2}). Stability is the main problem with amorphous silicon. Thin-film solar cells made from compound semiconductors do not have this problem, though their cost-effective series production needs to be shown still. The development potential of the three types mentioned will be ca. 30% in terms of efficiency: in terms of production cost, it is estimated with some certainty to be able to reach the baseline of 1 DM/Watt peak output (W{sub p}). (orig.).

  10. Multifractal characteristics of titanium nitride thin films

    Directory of Open Access Journals (Sweden)

    Ţălu Ştefan

    2015-09-01

    Full Text Available The study presents a multi-scale microstructural characterization of three-dimensional (3-D micro-textured surface of titanium nitride (TiN thin films prepared by reactive DC magnetron sputtering in correlation with substrate temperature variation. Topographical characterization of the surfaces, obtained by atomic force microscopy (AFM analysis, was realized by an innovative multifractal method which may be applied for AFM data. The surface micromorphology demonstrates that the multifractal geometry of TiN thin films can be characterized at nanometer scale by the generalized dimensions Dq and the singularity spectrum f(α. Furthermore, to improve the 3-D surface characterization according with ISO 25178-2:2012, the most relevant 3-D surface roughness parameters were calculated. To quantify the 3-D nanostructure surface of TiN thin films a multifractal approach was developed and validated, which can be used for the characterization of topographical changes due to the substrate temperature variation.

  11. Nanostructured thin films and coatings mechanical properties

    CERN Document Server

    2010-01-01

    The first volume in "The Handbook of Nanostructured Thin Films and Coatings" set, this book concentrates on the mechanical properties, such as hardness, toughness, and adhesion, of thin films and coatings. It discusses processing, properties, and performance and provides a detailed analysis of theories and size effects. The book presents the fundamentals of hard and superhard nanocomposites and heterostructures, assesses fracture toughness and interfacial adhesion strength of thin films and hard nanocomposite coatings, and covers the processing and mechanical properties of hybrid sol-gel-derived nanocomposite coatings. It also uses nanomechanics to optimize coatings for cutting tools and explores various other coatings, such as diamond, metal-containing amorphous carbon nanostructured, and transition metal nitride-based nanolayered multilayer coatings.

  12. Domains in Ferroic Crystals and Thin Films

    CERN Document Server

    Tagantsev, Alexander K; Fousek, Jan

    2010-01-01

    Domains in Ferroic Crystals and Thin Films presents experimental findings and theoretical understanding of ferroic (non-magnetic) domains developed during the past 60 years. It addresses the situation by looking specifically at bulk crystals and thin films, with a particular focus on recently-developed microelectronic applications and methods for observation of domains with techniques such as scanning force microscopy, polarized light microscopy, scanning optical microscopy, electron microscopy, and surface decorating techniques. Domains in Ferroic Crystals and Thin Films covers a large area of material properties and effects connected with static and dynamic properties of domains, which are extremely relevant to materials referred to as ferroics. In most solid state physics books, one large group of ferroics is customarily covered: those in which magnetic properties play a dominant role. Numerous books are specifically devoted to magnetic ferroics and cover a wide spectrum of magnetic domain phenomena. In co...

  13. Vibration welding system with thin film sensor

    Science.gov (United States)

    Cai, Wayne W; Abell, Jeffrey A; Li, Xiaochun; Choi, Hongseok; Zhao, Jingzhou

    2014-03-18

    A vibration welding system includes an anvil, a welding horn, a thin film sensor, and a process controller. The anvil and horn include working surfaces that contact a work piece during the welding process. The sensor measures a control value at the working surface. The measured control value is transmitted to the controller, which controls the system in part using the measured control value. The thin film sensor may include a plurality of thermopiles and thermocouples which collectively measure temperature and heat flux at the working surface. A method includes providing a welder device with a slot adjacent to a working surface of the welder device, inserting the thin film sensor into the slot, and using the sensor to measure a control value at the working surface. A process controller then controls the vibration welding system in part using the measured control value.

  14. Epitaxial integration of a nanoscale BiFeO3 phase boundary with silicon

    Science.gov (United States)

    Liang, Wen-I.; Peng, Chun-Yen; Huang, Rong; Kuo, Wei-Cheng; Huang, Yen-Chin; Adamo, Carolina; Chen, Yi-Chun; Chang, Li; Juang, Jenh-Yih; Schlom, Darrel G.; Chu, Ying-Hao

    2016-01-01

    The successful integration of the strain-driven nanoscale phase boundary of BiFeO3 onto a silicon substrate is demonstrated with extraordinary ferroelectricity and ferromagnetism. The detailed strain history is delineated through a reciprocal space mapping technique. We have found that a distorted monoclinic phase forms prior to a tetragonal-like phase, a phenomenon which may correlates with the thermal strain induced during the growth process.

  15. Regular nanodomain vertex arrays in BiFeO3 single crystals

    OpenAIRE

    Berger, A; Hesse, D.; Hähnel, A.; Arredondo-Arechavala, Miryam; Alexe, M.

    2012-01-01

    Domain patterns consisting of triangular nanodomains of less than 50 nm size, arranged into long regular vertex arrays separated by stripe domains, were observed by (scanning and high-resolution) transmission electron microscopy and piezoresponse force microscopy in BiFeO3 single crystals grown from solution flux. Piezoresponse force microscopy analysis together with crystallographic analysis by selected area and nanobeam electron diffraction indicate that these patterns consist of ferroelect...

  16. Strain-induced isosymmetric phase transition in BiFeO3

    OpenAIRE

    Ederer, Claude

    2009-01-01

    We calculate the effect of epitaxial strain on the structure and properties of multiferroic bismuth ferrite, BiFeO3, using first-principles density-functional theory. We investigate epitaxial strain corresponding to an (001)-oriented substrate and find that, while small strain causes only quantitative changes in behavior from the bulk material, compressive strains of greater than 4% induce an isosymmetric phase transition accompanied by a dramatic change in structure. In striking contrast to ...

  17. Photocatalytic activity of BiFeO3 nanoparticles synthesized through hydrothermal method

    International Nuclear Information System (INIS)

    Multiferroic BiFeO3 (BFO) nanoparticles (Nps) were synthesized using hydrothermal method. From the X-Ray diffraction analysis (XRD), the synthesized Nps were found to having rhombohedral structure with R3c space group confirmed by Rietveld analysis. Fourier transform infrared spectroscopy (FTIR) analysis was carried out to identify the chemical bonds present in the BFO Nps. Photocatalytic properties of synthesized Nps were studied for the degradation of Methylene Blue (MB) dye under visible light of 150W

  18. Controlled preparation and structure characterization of BiFeO3 with macroscopic shapes

    International Nuclear Information System (INIS)

    Graphical abstract: We firstly explored two facile and successful techniques for BiFeO3 immobilization on silica fiber, namely, a combined impregnation method with carbon nanofibers (CNFs) templates route, and a combined solvothermal method with CNFs templates route. It is expected that such materials with direct macroscopic shapes would hold promise as highly functionalized materials for potential practical applications, especially in photocatalysis. - Highlights: • BiFeO3 with macroscopic shape was successfully obtained. • The synthetic methods used here are facile, effective, and reproducible. • Phase composition was strongly affected by calcination temperatures. • The obtained materials are promising visible-light-driven photocatalysts. - Abstract: BiFeO3 was successfully immobilized on silica fiber via two synthetic techniques (a combined impregnation method with carbon nanofibers templates route; a combined solvothermal method with carbon nanofibers templates route). The phase structure, morphology and optical absorption property of the samples were characterized by X-ray diffraction, field emission scanning electron microscopy, and ultraviolet–visible diffuse reflectance spectroscopy. The results confirmed that carbon nanofibers can act as effective templates for BiFeO3 immobilization on silica fiber with the applied two methods. Compared with solvent thermal method, impregnation method tends to form a relatively uniform particle size distribution and highly-crystallized phase when the calcination temperature was kept at 773 K for 5 h. It turned out the phase composition of the samples is strongly affected by the calcination temperatures for both cases. Such materials with direct macroscopic shapes would hold promise as highly functionalized materials for potential practical applications, especially in photocatalysis

  19. Magnetically actuated peel test for thin films

    International Nuclear Information System (INIS)

    Delamination along thin film interfaces is a prevalent failure mechanism in microelectronic, photonic, microelectromechanical systems, and other engineering applications. Current interfacial fracture test techniques specific to thin films are limited by either sophisticated mechanical fixturing, physical contact near the crack tip, or complicated stress fields. Moreover, these techniques are generally not suitable for investigating fatigue crack propagation under cyclical loading. Thus, a fixtureless and noncontact experimental test technique with potential for fatigue loading is proposed and implemented to study interfacial fracture toughness for thin film systems. The proposed test incorporates permanent magnets surface mounted onto micro-fabricated released thin film structures. An applied external magnetic field induces noncontact loading to initiate delamination along the interface between the thin film and underlying substrate. Characterization of the critical peel force and peel angle is accomplished through in situ deflection measurements, from which the fracture toughness can be inferred. The test method was used to obtain interfacial fracture strength of 0.8-1.9 J/m2 for 1.5-1.7 μm electroplated copper on natively oxidized silicon substrates. - Highlights: ► Non-contact magnetic actuation test for interfacial fracture characterization. ► Applied load is determined through voltage applied to the driving electromagnet. ► Displacement and delamination propagation is measured using an optical profiler. ► Critical peel force and peel angle is measured for electroplated Cu thin-film on Si. ► The measured interfacial fracture energy of Cu/Si interface is 0.8-1.9 J/m2.

  20. Size dependent magnetic and electrical properties of Ba-doped nanocrystalline BiFeO3

    Directory of Open Access Journals (Sweden)

    Mehedi Hasan

    2016-03-01

    Full Text Available Improvement in magnetic and electrical properties of multiferroic BiFeO3 in conjunction with their dependence on particle size is crucial due to its potential applications in multifunctional miniaturized devices. In this investigation, we report a study on particle size dependent structural, magnetic and electrical properties of sol-gel derived Bi0.9Ba0.1FeO3 nanoparticles of different sizes ranging from ∼ 12 to 49 nm. The substitution of Bi by Ba significantly suppresses oxygen vacancies, reduces leakage current density and Fe2+ state. An improvement in both magnetic and electrical properties is observed for 10 % Ba-doped BiFeO3 nanoparticles compared to its undoped counterpart. The saturation magnetization of Bi0.9Ba0.1FeO3 nanoparticles increase with reducing particle size in contrast with a decreasing trend of ferroelectric polarization. Moreover, a first order metamagnetic transition is noticed for ∼ 49 nm Bi0.9Ba0.1FeO3 nanoparticles which disappeared with decreasing particle size. The observed strong size dependent multiferroic properties are attributed to the complex interaction between vacancy induced crystallographic defects, multiple valence states of Fe, uncompensated surface spins, crystallographic distortion and suppression of spiral spin cycloid of BiFeO3.

  1. Effect of sintering temperature on the optical properties of BiFeO3 nanoparticles

    Science.gov (United States)

    Jalandhara, Devender; Singh, Gurdhir; Yadav, Kamlesh

    2016-05-01

    BiFeO3 is a multiferroic material which exhibits excellent optical properties. BiFeO3 nanoparticles are synthesized by using sol-gel method. The prepared samples are sintered at 500°C, 600°C, 700°C, 800°C and 850°C. In this paper, the effect of sintering temperature on the optical properties in BiFeO3 nanoparticles is studied. Field emission electron microscopy (FESEM) images show that particles are nearly spherical in shape. It is found that the particles size increases from 37 nm to 51 nm with increasing the sintering temperature. FESEM images also reveal a homogenous size distribution of nanoparticles. All the functional groups are indexed in the Fourier transform infrared spectroscopy (FTIR) spectra. It is found that Fe-O stretching peaks are appeared in the wave number range 447 and 507 cm-1. The value of energy band gap are found 2.14, 2.26, 2.30, 2.36, and 2.54 eV for the samples sintered at 500°C, 600°C, 700°C, 800°C and 850°C respectively. Thus, the increase in band gap with increasing temperature has been observed. The present samples can be used as photo-catalyst, in non-volatile memories and to make spintronics devices.

  2. BiFeO3 as electrode material for lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Shihai, Luo; Mei, Gao; Jun, Chen; Xianran, Xing; Zhong, Li; Xingtai, Zhou; Wen, Wen

    2011-01-15

    Various electrode materials have been investigated as potential ones for lithium ion battery applications. However, to explore new materials for energy storage is very important, especially for those having potential to be used in electric vehicles. In this study, powdered BiFeO3 was synthesized using a molten salt method and was used as electrode material for lithium battery application. The structural transformations occurring during the electrochemical cycling process were investigated using the synchrotron in situ XRD and XANES, by which not only the phase transitions can be observed in the real time but also much better signal to noise ratio can be obtained due to its flux. Lithium ions were inserted into BiFeO3 during the discharge process and results indicated that Ni ions are responsible for charge transfer during the electrochemical cycling process. The reduction of Bi as the gradual insertion of Li ions, is a three step reproduction process. Future work to stabilize the lithiated BiFeO3 lattice is ongoing.

  3. Size dependent magnetic and electrical properties of Ba-doped nanocrystalline BiFeO3

    Science.gov (United States)

    Hasan, Mehedi; Hakim, M. A.; Basith, M. A.; Hossain, Md. Sarowar; Ahmmad, Bashir; Zubair, M. A.; Hussain, A.; Islam, Md. Fakhrul

    2016-03-01

    Improvement in magnetic and electrical properties of multiferroic BiFeO3 in conjunction with their dependence on particle size is crucial due to its potential applications in multifunctional miniaturized devices. In this investigation, we report a study on particle size dependent structural, magnetic and electrical properties of sol-gel derived Bi0.9Ba0.1FeO3 nanoparticles of different sizes ranging from ˜ 12 to 49 nm. The substitution of Bi by Ba significantly suppresses oxygen vacancies, reduces leakage current density and Fe2+ state. An improvement in both magnetic and electrical properties is observed for 10 % Ba-doped BiFeO3 nanoparticles compared to its undoped counterpart. The saturation magnetization of Bi0.9Ba0.1FeO3 nanoparticles increase with reducing particle size in contrast with a decreasing trend of ferroelectric polarization. Moreover, a first order metamagnetic transition is noticed for ˜ 49 nm Bi0.9Ba0.1FeO3 nanoparticles which disappeared with decreasing particle size. The observed strong size dependent multiferroic properties are attributed to the complex interaction between vacancy induced crystallographic defects, multiple valence states of Fe, uncompensated surface spins, crystallographic distortion and suppression of spiral spin cycloid of BiFeO3.

  4. Hydrothermal Synthesis of BiFeO3 Nanoparticles for Visible Light Photocatalytic Applications.

    Science.gov (United States)

    Niu, Feng; Gao, Tong; Zhang, Ning; Chen, Zhi; Huang, Qiaoli; Qin, Laishun; Sun, Xingguo; Huang, Yuexiang

    2015-12-01

    Bismuth ferrite is a promising material for visible light response photocatalytic applications due to its narrow band gap. In this work, single crystalline BiFeO3 nanoparticles were prepared by a modified hydrothermal process. The effects of hydrothermal temperature, reaction time and precursor xerogel amoumt on the as-prepared BiFeO3 particle size and morphology were investigated by XRD, TEM and HRTEM. The XRD analysis reveals that single crystalline BiFeO3 particles can be obtained when the hydrothermal temperature is kept below 220 degrees C. TEM observation showed that the as-formed BFO particles are in a square or rectangle-like shape and that the particle size is increased with increasing hydrothermal temperature. The hydrothermal reaction time and the amount of xerogel could also influence the as-formed BFO particle morphology and size. The band gap of the as-prepared BFO nanoparticles was identified by UV-vis diffuse reflectance spectrum. The measurement of photodegradation of methyl orange dye in an aqueous solution revealed that the as-prepared BFO nanoparticles exhibit photocatalytic activity under visible light irradiation. PMID:26682398

  5. Tailoring electronic structure of polyazomethines thin films

    Directory of Open Access Journals (Sweden)

    J. Weszka

    2010-09-01

    Full Text Available Purpose: The aim of this work is to show how electronic properties of polyazomethine thin films deposited by chemical vapor deposition method (CVD can be tailored by manipulating technological parameters of pristine films preparation as well as modifying them while the as-prepared films put into iodine atmosphere.Design/methodology/approach: The recent achievements in the field of designing and preparation methods to be used while preparing polymer photovoltaic solar cells or optoelectronic devices.Findings: The method used allow for pure pristine polymer thin films to be prtepared without any unintentional doping taking place during prepoaration methods. This is a method based on polycondensation process, where polymer chain developing is running directly due to chemical reaction between molecules of bifunctional monomers. The method applied to prepare thin films of polyazomethines takes advantage of monomer transporting by mreans of neutral transport agent as pure argon is.Research limitations/implications: The main disadvantage of alternately conjugated polymers seems to be quite low mobility of charge carrier that is expected to be a consequence of their backbone being built up of sp2 hybridized carbon and nitrogen atoms. Varying technological conditions towards increasing reagents mass transport to the substrate is expected to give such polyazomethine thin films organization that phenylene rin stacking can result in special π electron systems rather than linear ones as it is the case.Originality/value: Our results supply with original possibilities which can be useful in ooking for good polymer materials for optoelectronic and photovoltaic applications. These results have been gained on polyazomethine thin films but their being isoelectronic counterpart to widely used poly p-phenylene vinylene may be very convenient to develop high efficiency polymer solar cells

  6. Bilaterally Microstructured Thin Polydimethylsiloxane Film Production

    DEFF Research Database (Denmark)

    Vudayagiri, Sindhu; Yu, Liyun; Hassouneh, Suzan Sager;

    2015-01-01

    Thin PDMS films with complex microstructures are used in the manufacturing of dielectric electro active polymer (DEAP) actuators, sensors and generators, to protect the metal electrode from large strains and to assure controlled actuation. The current manufacturing process at Danfoss Polypower A...... with the existing manufacturing process. In employing the new technique, films with microstructures on both surfaces are successfully made with two different liquid silicone rubber (LSR) formulations: 1) pure XLR630 and 2) XLR630 with titanium dioxide (TiO2). The LSR films (∼70 μm) are cast on a....../S produces films with a one-sided microstructured surface only. It would be advantageous to produce a film with both surfaces microstructured, as this increases the film’s performance efficiency. The new technique introduced herein produces bilaterally microstructured film by combining an embossing method...

  7. Thin film oxygen partial pressure sensor

    Science.gov (United States)

    Wortman, J. J.; Harrison, J. W.; Honbarrier, H. L.; Yen, J.

    1972-01-01

    The development is described of a laboratory model oxygen partial pressure sensor using a sputtered zinc oxide thin film. The film is operated at about 400 C through the use of a miniature silicon bar. Because of the unique resistance versus temperature relation of the silicon bar, control of the operational temperature is achieved by controlling the resistance. A circuit for accomplishing this is described. The response of sputtered zinc oxide films of various thicknesses to oxygen, nitrogen, argon, carbon dioxide, and water vapor caused a change in the film resistance. Over a large range, film conductance varied approximately as the square root of the oxygen partial pressure. The presence of water vapor in the gas stream caused a shift in the film conductance at a given oxygen partial pressure. A theoretical model is presented to explain the characteristic features of the zinc oxide response to oxygen.

  8. Solid-state thin-film supercapacitor with ruthenium oxide and solid electrolyte thin films

    Science.gov (United States)

    Yoon, Y. S.; Cho, W. I.; Lim, J. H.; Choi, D. J.

    Direct current reactive sputtering deposition of ruthenium oxide thin films (bottom and top electrodes) at 400°C are performed to produce a solid-state thin-film supercapacitor (TFSC). The supercapacitor has a cell structure of RuO 2/Li 2.94PO 2.37N 0.75 (Lipon)/RuO 2/Pt. Radio frequency, reactive sputtering deposition of an Li 2.94PO 2.37N 0.75 electrolyte film is performed on the bottom RuO 2 film at room temperature to separate the bottom and top RuO 2 electrodes electrically. The stoichiometry of the RuO 2 thin film is investigated by Rutherford back-scattering spectrometry (RBS). X-ray diffraction (XRD) shows that the as-deposited RuO 2 thin film is an amorphous phase. Scanning electron microscopy (SEM) measurements reveal that the RuO 2/Lipon/RuO 2 hetero-interfaces have no inter-diffusion problems. Charge-discharge measurements with constant current at room temperature clearly reveal typical supercapacitor behaviour for a RuO 2/Lipon/RuO 2/Pt cell structure. Since the electrolyte thin film has low ionic mobility, the capacity and cycle performance are inferior to those of a bulk type of supercapacitor. These results indicate that a high performance, TFSC can be fabricated by a solid electrolyte thin film with high ionic conductivity.

  9. Functional planar thin film optical waveguide lasers

    International Nuclear Information System (INIS)

    Fabrication and characterization of planar and channel waveguiding thin films with the goal to develop active and passive elements are intensively studied over the last 20 years. Large scale of materials and properties were tested (morphology, crystallinity, luminescence, waveguiding, etc.). The goal of our contribution is to give an overview of materials and fabrication processes which were used for development and construction of functional planar waveguide lasers (PWL). The compact survey of finalized PWL and their basic parameters is given. A special part is devoted to fabrication of waveguide lasers using laser technology. Applications of thin film waveguide lasers are mentioned

  10. Advances in thin-film solar cells

    CERN Document Server

    Dharmadasa, I M

    2012-01-01

    This book concentrates on the latest developments in our understanding of solid-state device physics. The material presented is mainly experimental and based on CdTe thin-film solar cells. It extends these new findings to CIGS thin-film solar cells and presents a new device design based on graded bandgap multilayer solar cells. This design has been experimentally tested using the well-researched GaAs/AlGaAs system and initial devices have shown impressive device parameters. These devices are capable of absorbing all radiation (UV, visible, and infra-red) within the solar spectrum and combines

  11. Thin Films Made Fast and Modified Fast

    International Nuclear Information System (INIS)

    Thin films are playing a more and more important role for technological applications and there are many aspects of materials surface processing and thin film production, ranging from simple heat treatments to ion implantation or laser surface treatments. These methods are often very complicated, involving many basic processes and they have to be optimized for the desired application. Nuclear methods, especially Moessbauer spectroscopy, can be successfully applied for this task and some examples will be presented for laser-beam and ion-beam based processes.

  12. Intrinsically conductive polymer thin film piezoresistors

    DEFF Research Database (Denmark)

    Lillemose, Michael; Spieser, Martin; Christiansen, N.O.;

    2008-01-01

    We report on the piezoresistive effect in the intrinsically conductive polymer, polyaniline. A process recipe for indirect patterning of thin film polyaniline has been developed. Using a specially designed chip, the polyaniline thin films have been characterised with respect to resistivity and...... strain sensitivity using two- and four-point measurement method. We have found that polyaniline has a negative gauge factor of K = -4.9, which makes it a candidate for piezoresistive read-out in polymer based MEMS-devices. (C) 2007 Elsevier B.V. All rights reserved....

  13. Electrical analysis of niobium oxide thin films

    International Nuclear Information System (INIS)

    In this work, a series of niobium oxide thin films was deposited by reactive magnetron sputtering. The total pressure of Ar/O2 was kept constant at 1 Pa, while the O2 partial pressure was varied up to 0.2 Pa. The depositions were performed in a grounded and non-intentionally heated substrate, resulting in as-deposited amorphous thin films. Raman spectroscopy confirmed the absence of crystallinity. Dielectric measurements as a function of frequency (40 Hz–110 MHz) and temperature (100 K–360 K) were performed. The dielectric constant for the film samples with thickness (d) lower than 650 nm decreases with the decrease of d. The same behaviour was observed for the conductivity. These results show a dependence of the dielectric permittivity with the thin film thickness. The electrical behaviour was also related with the oxygen partial pressure, whose increment promotes an increase of the Nb2O5 stoichiometry units. - Highlights: • Niobium oxide thin films were deposited by reactive magnetron sputtering. • XRD showed a phase change with the increase of the P(O2). • Raman showed that increasing P(O2), Nb2O5 amorphous increases. • Conductivity tends to decrease with the increase of P(O2). • Dielectric analysis indicates the inexistence of preferential grow direction

  14. Perovskite Thin Films via Atomic Layer Deposition

    KAUST Repository

    Sutherland, Brandon R.

    2014-10-30

    © 2014 Wiley-VCH Verlag GmbH & Co. KGaA. (Graph Presented) A new method to deposit perovskite thin films that benefit from the thickness control and conformality of atomic layer deposition (ALD) is detailed. A seed layer of ALD PbS is place-exchanged with PbI2 and subsequently CH3NH3PbI3 perovskite. These films show promising optical properties, with gain coefficients of 3200 ± 830 cm-1.

  15. Dynamics of liquid films and thin jets

    Science.gov (United States)

    Zak, M.

    1979-01-01

    The theory of liquid films and thin jets as one- and two-dimensional continuums is examined. The equations of motion have led to solutions for the characteristic speeds of wave propagation for the parameters characterizing the shape. The formal analogy with a compressible fluid indicates the possibility of shock wave generation in films and jets and the formal analogy to the theory of threads and membranes leads to the discovery of some new dynamic effects. The theory is illustrated by examples.

  16. Viscous fingering in volatile thin films

    OpenAIRE

    Agam, Oded

    2008-01-01

    A thin water film on a cleaved mica substrate undergoes a first order phase transition between two values of film thickness. By inducing a finite evaporation rate of the water, the interface between the two phases develops a fingering instability similar to that observed in the Saffman-Taylor problem. We draw the connection between the two problems, and construct solutions describing the dynamics of evaporation in this system.

  17. Thin film dynamics with surfactant phase transition

    OpenAIRE

    Köpf, M. H.; Gurevich, S. V.; Friedrich, R.

    2009-01-01

    A thin liquid film covered with an insoluble surfactant in the vicinity of a first-order phase transition is discussed. Within the lubrication approximation we derive two coupled equations to describe the height profile of the film and the surfactant density. Thermodynamics of the surfactant is incorporated via a Cahn-Hilliard type free-energy functional which can be chosen to describe a transition between two stable phases of different surfactant density. Within this model, a linear stabilit...

  18. Mechanical integrity of thin films

    International Nuclear Information System (INIS)

    Mechanical considerations starting with the initial film deposition including questions of adhesion and grading the interface are reviewed. Growth stresses, limiting thickness, stress relief, control aging, and creep are described

  19. YBCO thin films in ac and dc films

    CERN Document Server

    Shahzada, S

    2001-01-01

    We report studies on the dc magnetization of YBCO thin films in simultaneously applied dc and ac fields. The effect of the ac fields is to decrease the irreversible magnetization drastically leading to complete collapse of the hysteresis loops for relatively small ac fields (250e). The magnitude of the decrease depends on the component of the ac field parallel to the c-axis. The decrease is non-linear with ac amplitude and is explained in the framework of the critical state response of ultra thin films in perpendicular geometry. The ac fields increase the relaxation rapidly at short times while the long time response appears unaffected. (author)

  20. Biaxial Fatigue Testing of Thin Films

    International Nuclear Information System (INIS)

    A new experimental setup, which allows for testing in an equi-biaxial loading condition, has been developed and applied to investigate the fatigue behaviour of thin films. A load controlled cycling, performed at room temperature on flat specimens, reproduces the strain amplitude and mean strain in the film corresponding to a thermal cycling in a given temperature range. The setup is based on the ring-on-ring test, which has been successfully used in biaxial fracture testing of glass and ceramics, and includes an optical in-situ failure detection system. The method is validated for specimens consisting in a gold film deposited on a polymer substrate

  1. Study of iron mononitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tayal, Akhil, E-mail: mgupta@csr.res.in; Gupta, Mukul, E-mail: mgupta@csr.res.in; Phase, D. M., E-mail: mgupta@csr.res.in; Reddy, V. R., E-mail: mgupta@csr.res.in; Gupta, Ajay, E-mail: mgupta@csr.res.in [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore,-452001 (India)

    2014-04-24

    In this work we have studied the crystal structural and local ordering of iron and nitrogen in iron mononitride thin films prepared using dc magnetron sputtering at sputtering power of 100W and 500W. The films were sputtered using pure nitrogen to enhance the reactivity of nitrogen with iron. The x-ray diffraction (XRD), conversion electron Mössbauer spectroscopy (CEMS) and soft x-ray absorption spectroscopy (SXAS) studies shows that the film crystallizes in ZnS-type crystal structure.

  2. Energetic Deposition of Niobium Thin Film in Vacuum

    OpenAIRE

    Wu, Genfa

    2002-01-01

    Niobium thin films are expected to be free of solid inclusions commonly seen in solid niobium. For particle accelerators, niobium thin film has the potential to replace the solid niobium in the making of the accelerating structures. In order to understand and improve the superconducting performance of niobium thin films at cryogenic temperature, an energetic vacuum deposition system has been developed to study deposition energy effects on the properties of niobium thin films on various substr...

  3. Correlated dewetting patterns in thin polystyrene films

    International Nuclear Information System (INIS)

    We describe preliminary results of experiments and simulations concerned with the dewetting of thin polystyrene films (thickness < 7 nm) on top of silicon oxide wafers. In the experiments we scratched an initially flat film with an atomic force microscopy (AFM) tip, producing dry channels in the film. Dewetting of the films was imaged in situ using AFM and a correlated pattern of holes ('satellite holes') was observed along the rims bordering the channels. The development of this complex film rupture process was simulated and the results of experiments and simulations are in good agreement. On the basis of these results, we attempt to explain the appearance of satellite holes and their positions relative to pre-existing holes

  4. Humidity sensing characteristics of hydrotungstite thin films

    Indian Academy of Sciences (India)

    G V Kunte; S A Shivashankar; A M Umarji

    2008-11-01

    Thin films of the hydrated phase of tungsten oxide, hydrotungstite (H2WO4.H2O), have been grown on glass substrates using a dip-coating technique. The -axis oriented films have been characterized by X-ray diffraction and scanning electron microscopy. The electrical conductivity of the films is observed to vary with humidity and selectively show high sensitivity to moisture at room temperature. In order to understand the mechanism of sensing, the films were examined by X-ray diffraction at elevated temperatures and in controlled atmospheres. Based on these observations and on conductivity measurements, a novel sensing mechanism based on protonic conduction within the surface layers adsorbed onto the hydrotungstite film is proposed.

  5. Correlated dewetting patterns in thin polystyrene films

    CERN Document Server

    Neto, C; Seemann, R; Blossey, R; Becker, J; Grün, G

    2003-01-01

    We describe preliminary results of experiments and simulations concerned with the dewetting of thin polystyrene films (thickness < 7 nm) on top of silicon oxide wafers. In the experiments we scratched an initially flat film with an atomic force microscopy (AFM) tip, producing dry channels in the film. Dewetting of the films was imaged in situ using AFM and a correlated pattern of holes ('satellite holes') was observed along the rims bordering the channels. The development of this complex film rupture process was simulated and the results of experiments and simulations are in good agreement. On the basis of these results, we attempt to explain the appearance of satellite holes and their positions relative to pre-existing holes.

  6. Resistance contact thin-film resistor

    Directory of Open Access Journals (Sweden)

    Spirin V. G.

    2008-10-01

    Full Text Available The analytical model of the calculation of the contact resistance of the thin-film resistor is Offered. The Explored dependency of the contact resistance from wedge of the pickling. The Considered influence adhesive layer on warm-up stability of the resistor. They Are Received formulas of the calculation systematic and casual inaccuracy contributed by contact resistance.

  7. New techniques for producing thin boron films

    International Nuclear Information System (INIS)

    A review will be presented of methods for producing thin boron films using an electron gun. Previous papers have had the problem of spattering of the boron source during the evaporation. Methods for reducing this problem will also be presented. 12 refs., 4 figs

  8. Electrical characterization of thin film ferroelectric capacitors

    NARCIS (Netherlands)

    Tiggelman, M.P.J.; Reimann, K.; Klee, M.; Beelen, D.; Keur, W.; Schmitz, J.; Hueting, R.J.E.

    2006-01-01

    Tunable capacitors can be used to facilitate the reduction of components in wireless technologies. The tunability of the capacitors is caused by the sensitivity of the relative dielectric constant to a change in polarization with electric field. Thin film ferroelectric MIM capacitors on silicon offe

  9. Ferromagnetic resonance in very thin films

    Czech Academy of Sciences Publication Activity Database

    Cochran, J. F.; Kamberský, Vladimír

    2006-01-01

    Roč. 302, - (2006), s. 348-361. ISSN 0304-8853 Institutional research plan: CEZ:AV0Z10100521 Keywords : ferromagnetic resonance * magnetic thin films Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.212, year: 2006

  10. Flexoelectricity in barium strontium titanate thin film

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Seol Ryung; Huang, Wenbin; Yuan, Fuh-Gwo; Jiang, Xiaoning, E-mail: xjiang5@ncsu.edu [Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Shu, Longlong [Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Electronic Materials Research Laboratory, International Center for Dielectric Research, Xi' an Jiao Tong University, Xi' an, Shaanxi 710049 (China); Maria, Jon-Paul [Department of Material Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2014-10-06

    Flexoelectricity, the linear coupling between the strain gradient and the induced electric polarization, has been intensively studied as an alternative to piezoelectricity. Especially, it is of interest to develop flexoelectric devices on micro/nano scales due to the inherent scaling effect of flexoelectric effect. Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} thin film with a thickness of 130 nm was fabricated on a silicon wafer using a RF magnetron sputtering process. The flexoelectric coefficients of the prepared thin films were determined experimentally. It was revealed that the thin films possessed a transverse flexoelectric coefficient of 24.5 μC/m at Curie temperature (∼28 °C) and 17.44 μC/m at 41 °C. The measured flexoelectric coefficients are comparable to that of bulk BST ceramics, which are reported to be 10–100 μC/m. This result suggests that the flexoelectric thin film structures can be effectively used for micro/nano-sensing devices.

  11. US Polycrystalline Thin Film Solar Cells Program

    Science.gov (United States)

    Ullal, Harin S.; Zweibel, Kenneth; Mitchell, Richard L.

    1989-11-01

    The Polycrystalline Thin Film Solar Cells Program, part of the United States National Photovoltaic Program, performs R and D on copper indium diselenide and cadmium telluride thin films. The objective of the program is to support research to develop cells and modules that meet the U.S. Department of Energy's long-term goals by achieving high efficiencies (15 to 20 percent), low-cost ($50/m(sup 2)), and long-time reliability (30 years). The importance of work in this area is due to the fact that the polycrystalline thin-film CuInSe2 and CdTe solar cells and modules have made rapid advances. They have become the leading thin films for PV in terms of efficiency and stability. The U.S. Department of Energy has increased its funding through an initiative through the Solar Energy Research Institute in CuInSe2 and CdTe with subcontracts to start in spring 1990.

  12. US polycrystalline thin film solar cells program

    Energy Technology Data Exchange (ETDEWEB)

    Ullal, H S; Zweibel, K; Mitchell, R L [Solar Energy Research Inst., Golden, CO (USA)

    1989-11-01

    The Polycrystalline Thin Film Solar Cells Program, part of the United States National Photovoltaic Program, performs R D on copper indium diselenide and cadmium telluride thin films. The objective of the Program is to support research to develop cells and modules that meet the US Department of Energy's long-term goals by achieving high efficiencies (15%-20%), low-cost ($50/m{sup 2}), and long-time reliability (30 years). The importance of work in this area is due to the fact that the polycrystalline thin-film CuInSe{sub 2} and CdTe solar cells and modules have made rapid advances. They have become the leading thin films for PV in terms of efficiency and stability. The US Department of Energy has increased its funding through an initiative through the Solar Energy Research Institute in CuInSe{sub 2} and CdTe with subcontracts to start in Spring 1990. 23 refs., 5 figs.

  13. A ferroelectric transparent thin-film transistor

    NARCIS (Netherlands)

    Prins, MWJ; GrosseHolz, KO; Muller, G; Cillessen, JFM; Giesbers, JB; Weening, RP; Wolf, RM

    1996-01-01

    Operation is demonstrated of a field-effect transistor made of transparant oxidic thin films, showing an intrinsic memory function due to the usage of a ferroelectric insulator. The device consists of a high mobility Sb-doped n-type SnO2 semiconductor layer, PbZr0.2Ti0.8Os3 as a ferroelectric insula

  14. Microwave-enhanced thin-film deposition

    Science.gov (United States)

    Chitre, S.

    1984-01-01

    The deposition of semiconducting and insulating thin films at low temperatures using microwave technology was explored. The method of plasma formations, selection of a power source, the design of the microwave plasma cavity, the microwave circuitry, impedance matching, plasma diagnostics, the deposition chamber and the vacuum system were studied.

  15. Rechargeable Thin-film Lithium Batteries

    Science.gov (United States)

    Bates, J. B.; Gruzalski, G. R.; Dudney, N. J.; Luck, C. F.; Yu, Xiaohua

    1993-08-01

    Rechargeable thin film batteries consisting of lithium metal anodes, an amorphous inorganic electrolyte, and cathodes of lithium intercalation compounds have recently been developed. The batteries, which are typically less than 6 {mu}m thick, can be fabricated to any specified size, large or small, onto a variety of substrates including ceramics, semiconductors, and plastics. The cells that have been investigated include Li TiS{sub 2}, Li V{sub 2}O{sub 5}, and Li Li{sub x}Mn{sub 2}O{sub 4}, with open circuit voltages at full charge of about 2.5, 3.6, and 4.2, respectively. The development of these batteries would not have been possible without the discovery of a new thin film lithium electrolyte, lithium phosphorus oxynitride, that is stable in contact with metallic lithium at these potentials. Deposited by rf magnetron sputtering of Li{sub 3}PO{sub 4} in N{sub 2}, this material has a typical composition of Li{sub 2.9}PO{sub 3.3}N{sub 0.46} and a conductivity at 25{degrees}C of 2 {mu}S/cm. The maximum practical current density obtained from the thin film cells is limited to about 100 {mu}A/cm{sup 2} due to a low diffusivity of Li{sup +} ions in the cathodes. In this work, the authors present a short review of their work on rechargeable thin film lithium batteries.

  16. Thermoviscoelastic models for polyethylene thin films

    DEFF Research Database (Denmark)

    Li, Jun; Kwok, Kawai; Pellegrino, Sergio

    2016-01-01

    This paper presents a constitutive thermoviscoelastic model for thin films of linear low-density polyethylene subject to strains up to yielding. The model is based on the free volume theory of nonlinear thermoviscoelasticity, extended to orthotropic membranes. An ingredient of the present approach...

  17. Surface spin slips in thin holmium films

    Directory of Open Access Journals (Sweden)

    F. H. S. Sales

    2012-09-01

    Full Text Available We report a theoretical investigation of new spin slips phases of thin holmium (Ho films. The new phases originate from the loss of coordination of atoms in the near surface region, which affects the balance between exchange and anisotropy energies, favoring the alignment of near surface spins along the basal plane easy axis directions.

  18. Monte Carlo simulation of magnetic nanostructured thin films

    Institute of Scientific and Technical Information of China (English)

    Guan Zhi-Qiang; Yutaka Abe; Jiang Dong-Hua; Lin Hai; Yoshitake Yamazakia; Wu Chen-Xu

    2004-01-01

    @@ Using Monte Carlo simulation, we have compared the magnetic properties between nanostructured thin films and two-dimensional crystalline solids. The dependence of nanostructured properties on the interaction between particles that constitute the nanostructured thin films is also studied. The result shows that the parameters in the interaction potential have an important effect on the properties of nanostructured thin films at the transition temperatures.

  19. Thin Films Characterization by Ultra Trace Metrology

    International Nuclear Information System (INIS)

    Sensitive and accurate characterization of thin films used in nanoelectronics, thinner than a few nm, represents a challenge for many conventional methods, especially when considering in-line control. With capabilities in the E10 at/cm2 (2O3 tunnel oxide deposited on a magnetic stack. On the other hand, composition analysis by TXRF, and especially the detection of minor elements into thin films, requires the use of a specific incident angle to optimize sensitivity. Under the best conditions, determination of the composition of Co -based self aligned barriers (CoWP and CoWMoPB films with Co concentration >80%) is done with a precision of 6% on P, 8% on Mo and 13% on W (standard deviation)

  20. Hematite thin films: growth and characterization

    Science.gov (United States)

    Uribe, J. D.; Osorio, J.; Barrero, C. A.; Giratá, D.; Morales, A. L.; Devia, A.; Gómez, M. E.; Ramirez, J. G.; Gancedo, J. R.

    We have grown hematite (α - Fe 2 O 3) thin films on stainless steel and (001)-silicon single-crystal substrates by RF magnetron sputtering process in argon atmosphere at substrate temperatures from 400 to 800°C. Conversion Electron Mössbauer (CEM) spectra of the sample grown on stainless steel at 400°C exhibit values for hyperfine parameter characteristic of bulk hematite phase in the weak ferromagnetic state. Also, the relative line intensity ratio suggests that the magnetization vector of the polycrystalline film is aligned preferentially parallel to the surface. The X-ray diffraction (XRD) pattern of the polycrystalline thin film grown on steel substrates also corresponds to α - Fe 2O3. The samples were also analyzed by Atomic Force Microscopy (AFM), those grown on stainless steel reveal a morphology consisting of columnar grains with random orientation, given the inhomogeneity of the substrate surface.

  1. Thin film bismuth iron oxides useful for piezoelectric devices

    Energy Technology Data Exchange (ETDEWEB)

    Zeches, Robert J.; Martin, Lane W.; Ramesh, Ramamoorthy

    2016-05-31

    The present invention provides for a composition comprising a thin film of BiFeO.sub.3 having a thickness ranging from 20 nm to 300 nm, a first electrode in contact with the BiFeO.sub.3 thin film, and a second electrode in contact with the BiFeO.sub.3 thin film; wherein the first and second electrodes are in electrical communication. The composition is free or essentially free of lead (Pb). The BFO thin film is has the piezoelectric property of changing its volume and/or shape when an electric field is applied to the BFO thin film.

  2. Factors controlling pure-phase magnetic BiFeO3 powders synthesized by solution combustion synthesis

    International Nuclear Information System (INIS)

    Highlights: → Both the type and amount of fuel strongly affect the phase composition and crystallinity of the as-synthesized product. → The system needs a careful optimisation of these parameters to obtain pure-phase and well-crystallized BiFeO3 nanopowders. An optimization of these parameters could improve the quality of the final products. → Among all tested fuels, L-α-alanine and glycine are the suitable fuel for BiFeO3 synthesis. The optimal fuel-to-oxidant ratio (F/NO3-) of α-alanine and glycine for pure-phase BiFeO3 synthesis is 0.22 (fuel-lean reaction, -33%) and 0.37 (fuel-lean reaction, -34%), respectively, which results in a suitable flame temperature that favors the formation of BiFeO3 phase. → Still, too little fuel would result in only amorphous phase powders due to the low flame temperature and too much fuel would lead to transformation of the BiFeO3 phase to impurities (Bi2Fe4O9 and Bi25FeO39 phases) because of the high flame temperature involved. → The resulting BiFeO3 nanopowders exhibited strong H2O2-activiting ability and weak magnetism. When BiFeO3 nanopowders were used as a heterogeneous Fenton-like catalyst to degrade rhodamine B (RhB), the apparent rate constant for RhB degradation in the presence of H2O2 at pH 5.0 was evaluated to be 0.048 min-1. - Abstract: Bismuth ferric oxide nanopowders were prepared through combustion method. Pure phase and well-crystallized BiFeO3 can be obtained by controlling the combustion process, fuel type and fuel-to-oxidant ratio. The evolutions of phase constitution and structural characteristics of the as-resulted nanopowders were investigated by X-ray diffraction, scanning electron microscope, and simultaneous thermogravimetric analysis. The results revealed that both the type and amount of fuel have to be carefully considered because they play an important role in total reaction characteristics. Among all tested fuels, L-α-alanine and glycine are the suitable fuels for BiFeO3 synthesis. For α-alanine, the optimal fuel-to-oxidant ratio is 0.22, which results in a suitable flame temperature for BiFeO3 formation. Still, too little fuel would result in only amorphous phase powders due to the low flame temperature and too much fuel would lead to transformation of the BiFeO3 phase to impurities because of the high flame temperature involved. The resulting BiFeO3 nanopowders exhibited strong H2O2-activiting ability and weak magnetism. When BiFeO3 nanopowders were used as a heterogeneous Fenton-like catalyst to degrade rhodamine B (RhB), the apparent rate constant for RhB degradation in the presence of H2O2 at pH 5.0 was evaluated to be 0.048 min-1

  3. Thin-film cadmium telluride solar cells

    Science.gov (United States)

    Chu, T. L.

    1987-10-01

    Cadmium telluride, with a room-temperature band-gap energy of 1.5 eV, is a promising thin-film photovoltaic material. The major objective of this research has been to demonstrate thin-film CdTe heterojunction solar cells with a total area greater than 1 sq cm and photovoltaic efficiencies of 13 percent or more. Thin-film p-CdTe/CdS/SnO2:F/glass solar cells with an AM1.5 efficiency of 10.5 percent have been reported previously. This report contains results of work done on: (1) the deposition, resistivity control, and characterization of p-CdTe films by the close-spaced sublimation process; (2) the deposition of large-band-gap window materials; (3) the electrical properties of CdS/CdTe heterojunctions; (4) the formation of stable, reproducible, ohmic contacts (such as p-HgTe) to p-CdTe; and (5) the preparation and evaluation of heterojunction solar cells.

  4. Energetic deposition of thin metal films

    CERN Document Server

    Al-Busaidy, M S K

    2001-01-01

    deposited films. The primary aim of this thesis was to study the physical effect of energetic deposition metal thin films. The secondary aim is to enhance the quality of the films produced to a desired quality. Grazing incidence X-ray reflectivity (GIXR) measurements from a high-energy synchrotron radiation source were carried out to study and characterise the samples. Optical Profilers Interferometery, Atomic Force Microscope (AFM), Auger electron spectroscopy (AES), Medium energy ion spectroscopy (MEIS), and the Electron microscope studies were the other main structural characterisation tools used. AI/Fe trilayers, as well as multilayers were deposited using a Nordico planar D.C. magnetron deposition system at different voltage biases and pressures. The films were calibrated and investigated. The relation between energetic deposition variation and structural properties was intensely researched. Energetic deposition refers to the method in which the deposited species possess higher kinetic energy and impact ...

  5. Basic thin film processing for high-Tc superconductors

    International Nuclear Information System (INIS)

    Much attention has been paid for the thin films of perovskite-type oxides especially for the thin films of the high-Tc superconducting ceramics. Historically the thin films of the perovskite-type oxides have been studied as a basic research for ferroelectric materials. Thin films of BaTiO3 and PbTiO3 were tried to deposited and there ferroelectricity was evaluated. Recently this kind of perovskite thin films, including PZT (PbTiO3-PbZrO3) and PLZT [(Pb, La) (Zr, T)O3] have been studied in relation to the synthesis of thin film dielectrics, pyroelectrics, piezoelectrics, electro-optic materials, and acousto-optic materials. Thin films of BPB (BaPbO3- BaBiO3) were studied as oxide superconductors. At present the thin films of the rare-earth high-Tc superconductors of LSC (La1-xSrxCuO4) and YBC (YBa2Cu3O7-δ) have been successfully synthesized owing to the previous studies on the ferroelectric thin films of the perovskite- type oxides. Similar to the rare-earth high-Tc superconductors thin films of the rare-earth-free high-Tc superconductors of BSCC (Bi-Sr-Ca-Cu-O)9 and TBCC (Tl- Ba-Ca-Cu-O)10 system have been synthesized. In this section the basic processes for the fabrication of the high- Tc perovskite superconducting thin films are described

  6. Structural transformation and multiferroic properties of Ba-Mn co-doped BiFeO3

    Science.gov (United States)

    Rout, Jyoshna; Choudhary, R. N. P.

    2016-01-01

    Pure BiFeO3 and Bi1-xBaxFe1-xMnxO3 (x = 0.10, 0.20) fine ceramics were synthesized using mechano-synthesis route. The influence of co-doping (Ba-Mn) on structural and multiferroic properties of BiFeO3 has been studied in different experimental conditions. X-ray diffraction patterns, Rietveld structural refinement of XRD patterns and Fourier transform infrared (FTIR) spectra reveal the structural transition from rhombohedral (R3c) to the biphasic structure (R3c + P4mm) on co-doping. The co-doping improves surface morphology and also reduces the particle size. The room temperature M-H loops of all samples showed antiferromagnetic/weak ferromagnetic behavior. Magnetoelectric coupling coefficient determination is carried out to reveal extent of intimate interaction between electric and magnetic dipoles interaction in the samples. Room temperature occurrence of ferromagnetism, ferroelectricity and magnetoelectric effect supports the observation of multiferroism and magnetoelectric coupling in BiFeO3. Thus, co-doping at Bi- and Fe-sites of BiFeO3 can improve multiferroic properties of BiFeO3 for various applications.

  7. Thin Films for Coating Nanomaterials

    Institute of Scientific and Technical Information of China (English)

    S.M.Mukhopadhyay; P.Joshi; R.V.Pulikollu

    2005-01-01

    For nano-structured solids (those with one or more dimensions in the 1-100 nm range), attempts of surface modification can pose significant and new challenges. In traditional materials, the surface coating could be several hundreds nanometers in thickness, or even microns and millimeters. In a nano-structured material, such as particle or nanofibers, the coating thickness has to be substantially smaller than the bulk dimensions (100 nm or less), yet be durable and effective. In this paper, some aspects of effective nanometer scale coatings have been discussed. These films have been deposited by a non-line of sight (plasma)techniques; and therefore, they are capable of modifying nanofibers, near net shape cellular foams, and other high porosity materials. Two types of coatings will be focused upon: (a) those that make the surface inert and (b) those designed to enhance surface reactivity and bonding. The former has been achieved by forming 1-2 nm layer of -CF2- (and/or CF3) groups on the surface, and the latter by creating a nanolayer of SiO2-type compound. Nucleation and growth studies of the plasma-generated film indicate that they start forming as 2-3 nm high islands that grow laterally, and eventually completely cover the surface with 2-3nm film. Contact angle measurements indicate that these nano-coatings are fully functional even before they have achieved complete coverage of 2-3 nm. They should therefore be applicable to nano-structural solids.This is corroborated by application of these films on vapor grown nanofibers of carbon, and on graphitic foams. Coated and uncoated materials are infiltrated with epoxy matrix to form composites and their microstructure, as well as mechanical behaviors are compared. The results show that the nano-oxide coating can significantly enhance bond formation between carbon and organic phases, thereby enhancing wettability,dispersion, and composite behavior. The fluorocarbon coating, as expected, reduces bond formation, and

  8. Optical thin films and coatings from materials to applications

    CERN Document Server

    Flory, Francois

    2013-01-01

    Optical coatings, including mirrors, anti-reflection coatings, beam splitters, and filters, are an integral part of most modern optical systems. This book provides an overview of thin film materials, the properties, design and manufacture of optical coatings and their use across a variety of application areas.$bOptical coatings, including mirrors, anti-reflection coatings, beam splitters, and filters, are an integral part of most modern optical systems. Optical thin films and coatings provides an overview of thin film materials, the properties, design and manufacture of optical coatings and their use across a variety of application areas. Part one explores the design and manufacture of optical coatings. Part two highlights unconventional features of optical thin films including scattering properties of random structures in thin films, optical properties of thin film materials at short wavelengths, thermal properties and colour effects. Part three focusses on novel materials for optical thin films and coatings...

  9. PLD-grown thin film saturable absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Tellkamp, Friedjof

    2012-11-01

    The subject of this thesis is the preparation and characterization of thin films made of oxidic dielectrics which may find their application as saturable absorber in passively Q-switched lasers. The solely process applied for fabrication of the thin films was the pulsed laser deposition (PLD) which stands out against other processes by its flexibility considering the composition of the systems to be investigated. Within the scope of this thesis the applied saturable absorbers can be divided into two fundamentally different kinds of functional principles: On the one hand, saturable absorption can be achieved by ions embedded in a host medium. Most commonly applied bulk crystals are certain garnets like YAG (Y{sub 3}Al{sub 5}O{sub 12}) or the spinel forsterite (Mg{sub 2}SiO{sub 4}), in each case with chromium as dopant. Either of these media was investigated in terms of their behavior as PLD-grown saturable absorber. Moreover, experiments with Mg{sub 2}GeO{sub 4}, Ca{sub 2}GeO{sub 4}, Sc{sub 2}O{sub 3}, and further garnets like YSAG or GSGG took place. The absorption coefficients of the grown films of Cr{sup 4+}:YAG were determined by spectroscopic investigations to be one to two orders of magnitude higher compared to commercially available saturable absorbers. For the first time, passive Q-switching of a Nd:YAG laser at 1064 nm with Cr{sup 4+}:YAG thin films could be realized as well as with Cr:Sc{sub 2}O{sub 3} thin films. On the other hand, the desirable effect of saturable absorption can also be generated by quantum well structures. For this purpose, several layer system like YAG/LuAG, Cu{sub 2}O/MgO, and ZnO/corumdum were investigated. It turned out that layer systems with indium oxide (In{sub 2}O{sub 3}) did not only grew in an excellent way but also showed up a behavior regarding their photo luminescence which cannot be explained by classical considerations. The observed luminescence at roughly 3 eV (410 nm) was assumed to be of excitonic nature and its

  10. Ferroelectric and ferromagnetic properties of Gd-modified BiFeO3

    International Nuclear Information System (INIS)

    The polycrystalline samples of gadolinium (Gd)-modified bismuth iron oxide, Bi1−xGdxFeO3 (BGFO) with x=0, 0.05, 0.15, 0.25 were prepared by a standard high-temperature solid-state reaction technique. A preliminary X-ray structural analysis was carried out to examine the structural deformation and stability of Gd-modified BiFeO3. Room temperature surface morphology and textures of the samples were recorded by a scanning electron microscope, which reveal the uniform distribution of the plate-and rod-shaped grains in the samples. The grain size decreases with increase of Gd content in BGFO. Studies of dielectric and electric properties in a wide range of frequency (1 kHz–1 MHz) and temperature (30–400 °C) using complex impedance spectroscopic method have provided many new results. With higher Gd-concentration, dielectric constant and tangent loss of BGFO increases and decreases respectively at room temperature. Generally, the spontaneous and remnant polarizations are found to be enhanced on Gd substitutions in BFO. Studies of temperature dependence of electrical conductivity exhibit that all the samples follow Arrhenius-type of electrical conductivities behavior. The frequency dependence of ac conductivity suggests that the samples obey Jonscher's universal power law. The magneto-electric coupling coefficient of BFO is enhanced on increasing Gd content in BGFO. - Highlights: • The value of tan δ decreases whereas εr increases on increasing Gd concentration in BiFeO3. • A significant effect of Gd-substitution on coercive field and remnant polarization was observed. • The magnetic moment, magneto-electric voltage and coupling coefficient of BiFeO3 are enhanced on Gd-substitution in it

  11. Thin film cadmium telluride solar cells

    Science.gov (United States)

    Chu, T. L.; Chu, Shirley S.; Ang, S. T.; Mantravadi, M. K.

    1987-08-01

    Thin-film p-CdTe/CdS/SnO2:F/glass solar cells of the inverted configuration were prepared by the deposition of p-type CdTe films onto CdS/SnO2:F/glass substrates using CVD or close-spaced sublimation (CSS) techniques based on the procedures of Chu et al. (1983) and Nicholl (1963), respectively. The deposition rates of p-CdTe films deposited by CSS were higher than those deposited by the CVD technique (4-5 min were sufficient), and the efficiencies higher than 10 percent were obtained. However, the resistivity of films prepared by CSS was not as readily controlled as that of the CVD films. The simplest technique to reduce the resistivity of the CSS p-CdTe films was to incorporate a dopant, such as As or Sb, into the reaction mixture during the preparation of the source material. The films with resistivities in the range of 500-1000 ohm cm were deposited in this manner.

  12. Non-local thin films in Casimir force calculations

    OpenAIRE

    Esquivel, R.; Svetovoy, V.

    2005-01-01

    he Casimir force is calculated between plates with thin metallic coating. Thin films are described with spatially dispersive (nonlocal) dielectric functions. For thin films the nonlocal effects are more relevant than for half-spaces. However, it is shown that even for film thickness smaller than the mean free path for electrons, the difference between local and nonlocal calculations of the Casimir force is of the order of a few tenths of a percent. Thus the local description of thin metallic ...

  13. Nitrogen doped zinc oxide thin film

    Energy Technology Data Exchange (ETDEWEB)

    Li, Sonny X.

    2003-12-15

    To summarize, polycrystalline ZnO thin films were grown by reactive sputtering. Nitrogen was introduced into the films by reactive sputtering in an NO{sub 2} plasma or by N{sup +} implantation. All ZnO films grown show n-type conductivity. In unintentionally doped ZnO films, the n-type conductivities are attributed to Zn{sub i}, a native shallow donor. In NO{sub 2}-grown ZnO films, the n-type conductivity is attributed to (N{sub 2}){sub O}, a shallow double donor. In NO{sub 2}-grown ZnO films, 0.3 atomic % nitrogen was found to exist in the form of N{sub 2}O and N{sub 2}. Upon annealing, N{sub 2}O decomposes into N{sub 2} and O{sub 2}. In furnace-annealed samples N{sub 2} redistributes diffusively and forms gaseous N{sub 2} bubbles in the films. Unintentionally doped ZnO films were grown at different oxygen partial pressures. Zni was found to form even at oxygen-rich condition and led to n-type conductivity. N{sup +} implantation into unintentionally doped ZnO film deteriorates the crystallinity and optical properties and leads to higher electron concentration. The free electrons in the implanted films are attributed to the defects introduced by implantation and formation of (N{sub 2}){sub O} and Zni. Although today there is still no reliable means to produce good quality, stable p-type ZnO material, ZnO remains an attractive material with potential for high performance short wavelength optoelectronic devices. One may argue that gallium nitride was in a similar situation a decade ago. Although we did not obtain any p-type conductivity, we hope our research will provide a valuable reference to the literature.

  14. Identifying the Magnetoelectric Modes of Multiferroic BiFeO3

    Energy Technology Data Exchange (ETDEWEB)

    Fishman, Randy Scott [ORNL; Furukawa, N. [Aoyama Gakuin University, Kanagawa, Japan; Haraldsen, Jason T. [Los Alamos National Laboratory (LANL); Matsuda, Masaaki [ORNL; Miyahara, Shinya [Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea

    2012-01-01

    We have identified three of the four magnetoelectric modes of multiferroic BiFeO3 measured using THz spectroscopy. Excellent agreement with the observed peaks is obtained by including the effects of easy-axis anisotropy along the direction of the electric polarization. By distorting the cycloidal spin state, anisotropy splits the 1 mode into peaks at 20 and 21.5 cm 1 and activates the lower 2 mode at 27 cm 1 (T = 200 K). An electromagnon is identified with the upper 1 mode at 21.5 cm 1. Our results also explain recent Raman and inelastic neutron-scattering measurements.

  15. Local Weak Ferromagnetism in Single-Crystalline Ferroelectric BiFeO3

    OpenAIRE

    Ramazanoglu, M.; Laver, Mark; Ratcliff, W.; Watson, S. M.; Chen, W. C.; Jackson, A; Kothapalli, K.; Lee, S; Cheong, S.-W.; Kiryukhin, V.

    2011-01-01

    Polarized small-angle neutron scattering studies of single-crystalline multiferroic BiFeO3 reveal a long-wavelength spin density wave generated by ∼1° spin canting of the spins out of the rotation plane of the antiferromagnetic cycloidal order. This signifies weak ferromagnetism within mesoscopic regions of dimension 0.03 microns along [11̅ 0], to several microns along [111], confirming a long-standing theoretical prediction. The average local magnetization is 0.06  μB/Fe. Our results provide...

  16. Lanthanum doped BiFeO3 powders: Syntheses and characterization

    International Nuclear Information System (INIS)

    A soft chemistry route was employed to fabricate single-phase lanthanum modified BiFeO3 (BFO) powders. Effects of lanthanum concentration on the phase formation, grain size and morphologies of BFO powders were systematically investigated. X-ray diffraction results indicated that perovskite phase have been synthesized at the temperature of 850 oC/2 h while infrared data indicates no traces of carbonate. Raman analysis reveals that lanthanum atom substitutes bismuth into the BFO site. A homogeneous size distribution of BFO powders was evidenced by scanning electron microscopy.

  17. Enhanced magnetic and dielectric behavior in Co doped BiFeO3 nanoparticles

    International Nuclear Information System (INIS)

    Magnetic and dielectric properties of Co doped BiFeO3 (BFO) nanoparticles (13 nm) have been investigated. The dopant Co2+ converts spherical morphology to cubic nanostructures. The significant changes in temperature dependence of magnetization may be due to magnetic disorder phase induced by divalent Co. The substitution of Fe by Co disrupts cycloidal spin structure of BFO and improves the ferromagnetic property. Enhancement of the saturation magnetization and coercivity by about 10 times in doped BFO are due to changes in morphology. High dielectric constant of about 670 and low loss at room temperature show Co doped BFO as promising material for multifunctional devices

  18. PST thin films for electrocaloric coolers

    International Nuclear Information System (INIS)

    Relaxor behaviour in a thin film of partially ordered PbSc0.5Ta0.5O3 (PST) was confirmed via slim P-E loops and the frequency dependence of the temperature at which the dielectric constant is maximum. Indirect measurements of the electrocaloric effect suggest that removing a field of 774 kV cm-1 yields a temperature change of -3.5 deg. C to -6.9 deg. C over a broad range of operating temperatures near room temperature (1-127 deg. C), with a correspondingly large refrigerant capacity of 662 J kg-1. In addition to low electrical hysteresis, there is negligible thermal hysteresis. PST thin films are therefore promising for EC cooling near room temperature.

  19. Generalized Ellipsometry on Ferromagnetic Sculptured Thin Films.

    Science.gov (United States)

    Schmidt, Daniel; Hofmann, Tino; Mok, Kah; Schmidt, Heidemarie; Skomski, Ralf; Schubert, Eva; Schubert, Mathias

    2011-03-01

    We present and discuss generalized ellipsometry and generalized vector-magneto-optic ellipsometry investigations on cobalt nanostructured thin films with slanted, highly-spatially coherent, columnar arrangement. The samples were prepared by glancing angle deposition. The thin films are highly transparent and reveal strong form-induced birefringence. We observe giant Kerr rotation in the visible spectral region, tunable by choice of the nanostructure geometry. Spatial magnetization orientation hysteresis and magnetization magnitude hysteresis properties are studied using a 3-dimensional Helmholtz coil arrangement allowing for arbitrary magnetic field direction at the sample position for field strengths up to 0.4 Tesla. Analysis of data obtained within this novel vector-magneto-optic setup reveals magnetization anisotropy of the Co slanted nanocolumns supported by mean-field theory modeling.

  20. Multiferroic oxide thin films and heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Chengliang, E-mail: cllu@mail.hust.edu.cn, E-mail: Tao.Wu@kaust.edu.sa [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Hu, Weijin; Wu, Tom, E-mail: cllu@mail.hust.edu.cn, E-mail: Tao.Wu@kaust.edu.sa [Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia); Tian, Yufeng [School of Physics, Shandong University, Jinan 250100 (China)

    2015-06-15

    Multiferroic materials promise a tantalizing perspective of novel applications in next-generation electronic, memory, and energy harvesting technologies, and at the same time they also represent a grand scientific challenge on understanding complex solid state systems with strong correlations between multiple degrees of freedom. In this review, we highlight the opportunities and obstacles in growing multiferroic thin films with chemical and structural integrity and integrating them in functional devices. Besides the magnetoelectric effect, multiferroics exhibit excellent resistant switching and photovoltaic properties, and there are plenty opportunities for them to integrate with other ferromagnetic and superconducting materials. The challenges include, but not limited, defect-related leakage in thin films, weak magnetism, and poor control on interface coupling. Although our focuses are Bi-based perovskites and rare earth manganites, the insights are also applicable to other multiferroic materials. We will also review some examples of multiferroic applications in spintronics, memory, and photovoltaic devices.

  1. Multiferroic oxide thin films and heterostructures

    KAUST Repository

    Lu, Chengliang

    2015-05-26

    Multiferroic materials promise a tantalizing perspective of novel applications in next-generation electronic, memory, and energy harvesting technologies, and at the same time they also represent a grand scientific challenge on understanding complex solid state systems with strong correlations between multiple degrees of freedom. In this review, we highlight the opportunities and obstacles in growing multiferroic thin films with chemical and structural integrity and integrating them in functional devices. Besides the magnetoelectric effect, multiferroics exhibit excellent resistant switching and photovoltaic properties, and there are plenty opportunities for them to integrate with other ferromagnetic and superconducting materials. The challenges include, but not limited, defect-related leakage in thin films, weak magnetism, and poor control on interface coupling. Although our focuses are Bi-based perovskites and rare earth manganites, the insights are also applicable to other multiferroic materials. We will also review some examples of multiferroic applications in spintronics, memory, and photovoltaic devices.

  2. Electrical characterization of thin film ferroelectric capacitors

    OpenAIRE

    Tiggelman, M.P.J.; Reimann, K.; Klee, M.; Beelen, D; Keur, W.; J. Schmitz; Hueting, R.J.E.

    2006-01-01

    Tunable capacitors can be used to facilitate the reduction of components in wireless technologies. The tunability of the capacitors is caused by the sensitivity of the relative dielectric constant to a change in polarization with electric field. Thin film ferroelectric MIM capacitors on silicon offer a re-use of electronic circuitry, low tuning voltages, a high capacitance density, a low cost, a presence of bulk acoustic wave resonance(s) and decoupling functionality. The basic operation and ...

  3. Quantized Nanocrystalline CdTe Thin Films

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Nanocrystalline CdTe thin films were prepared by asymmetric rectangular pulse electrodeposition in organic solution at 110°C. STM image shows a porous network morphology constructed by interconnected spherical CdTe crystallites with a mean diameter of 4.2 nm. A pronounced size quantization was indicated in the action and absorption spectra. Potentials dependence dual conductive behavior was revealed in the photocurrent-potential (I-V) curves.

  4. Amperometric Noise at Thin Film Band Electrodes

    DEFF Research Database (Denmark)

    Larsen, Simon T.; Heien, Michael L.; Taboryski, Rafael

    2012-01-01

    Background current noise is often a significant limitation when using constant-potential amperometry for biosensor application such as amperometric recordings of transmitter release from single cells through exocytosis. In this paper, we fabricated thin-film electrodes of gold and conductive...... presented here can be used for choosing an electrode material and dimensions and when designing chip-based devices for low-noise current measurements....

  5. Ferromagnetic Liquid Thin Films Under Applied Field

    OpenAIRE

    Banerjee, S.; Widom, M.

    1999-01-01

    Theoretical calculations, computer simulations and experiments indicate the possible existence of a ferromagnetic liquid state, although definitive experimental evidence is lacking. Should such a state exist, demagnetization effects would force a nontrivial magnetization texture. Since liquid droplets are deformable, the droplet shape is coupled with the magnetization texture. In a thin-film geometry in zero applied field, the droplet has a circular shape and a rotating magnetization texture ...

  6. Electrochemical Analysis of Conducting Polymer Thin Films

    OpenAIRE

    Bin Wang; Vyas, Ritesh N.

    2010-01-01

    Polyelectrolyte multilayers built via the layer-by-layer (LbL) method has been one of the most promising systems in the field of materials science. Layered structures can be constructed by the adsorption of various polyelectrolyte species onto the surface of a solid or liquid material by means of electrostatic interaction. The thickness of the adsorbed layers can be tuned precisely in the nanometer range. Stable, semiconducting thin films are interesting research subjects. We use a conducting...

  7. Thin-film silicon solar cell technology

    Energy Technology Data Exchange (ETDEWEB)

    Shah, A.V.; Meier, J.; Kroll, U.; Droz, C.; Bailat, J. [University of Neuchatel (Switzerland). Inst. of Microtechnology; Schade, H. [RWE Schott Solar GmbH, Putzbrunn (Germany); Vanecek, M. [Academy of Sciences, Prague (Czech Republic). Inst. of Physics; Vallat Sauvain, E.; Wyrsch, N. [University of Neuchatel (Switzerland). Inst. of Microtechnology; Unaxis SPTec S A, Neuchatel (Switzerland)

    2004-07-01

    This paper describes the use, within p-i-n- and n-i-p-type solar cells, of hydrogenated amorphous silicon (a-Si:H) and hydrogenated microcrystalline silicon ({mu}c-Si:H) thin films (layers), both deposited at low temperatures (200{sup o}C) by plasma-assisted chemical vapour deposition (PECVD), from a mixture of silane and hydrogen. Optical and electrical properties of the i-layers are described. These properties are linked to the microstructure and hence to the i-layer deposition rate, that in turn, affects throughput in production. The importance of contact and reflection layers in achieving low electrical and optical losses is explained, particularly for the superstrate case. Especially the required properties for the transparent conductive oxide (TCO) need to be well balanced in order to provide, at the same time, for high electrical conductivity (preferably by high electron mobility), low optical absorption and surface texture (for low optical losses and pronounced light trapping). Single-junction amorphous and microcrystalline p-i-n-type solar cells, as fabricated so far, are compared in their key parameters (J{sub sc},FF,V{sub oc}) with the [theoretical] limiting values. Tandem and multijunction cells are introduced; the {mu}c-Si: H/a-Si: H or [micromorph] tandem solar cell concept is explained in detail, and recent results obtained here are listed and commented. Factors governing the mass-production of thin-film silicon modules are determined both by inherent technical reasons, described in detail, and by economic considerations. The cumulative effect of these factors results in distinct efficiency reductions from values of record laboratory cells to statistical averages of production modules. Finally, applications of thin-film silicon PV modules, especially in building-integrated PV (BIPV) are shown. In this context, the energy yields of thin-film silicon modules emerge as a valuable gauge for module performance, and compare very favourably with those of

  8. Thin film sensors for measuring small forces

    OpenAIRE

    F. Schmaljohann; Hagedorn, D.; LÖffler, F.

    2015-01-01

    Especially in the case of measuring small forces, the use of conventional foil strain gauges is limited. The measurement uncertainty rises by force shunts and is due to the polymer foils used, as they are susceptible to moisture. Strain gauges in thin film technology present a potential solution to overcome these effects because of their direct and atomic contact with the measuring body, omitting an adhesive layer and the polymer foil. For force measurements up to 1 N, a...

  9. Structures for dense, crack free thin films

    Science.gov (United States)

    Jacobson, Craig P.; Visco, Steven J.; De Jonghe, Lutgard C.

    2011-03-08

    The process described herein provides a simple and cost effective method for making crack free, high density thin ceramic film. The steps involve depositing a layer of a ceramic material on a porous or dense substrate. The deposited layer is compacted and then the resultant laminate is sintered to achieve a higher density than would have been possible without the pre-firing compaction step.

  10. Recent developments in thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Dhere, N.G. (Inst. Militar de Engenharia, Rio de Janeiro, RJ (Brazil))

    1990-12-15

    In recent years, remarkable progress has been made in improving the photovoltaic (PV) conversion efficiencies of thin film solar cells. The best active-area efficiencies (air mass 1.5) of thin film solar cells reported are as follows: polycrystalline CuInSe{sub 2}, 14.1%; CuIn(Ga)Se{sub 2}, 12.9%; CdTe, 12.3%, total area; single-junction hydrogenated amorphous silicon (a-Si:H), 12.0%; multiple-junction a-Si:H, 13.3%; cleaved epitaxial GaAs-Ga{sub 1-x}Al{sub x}As, 21.5%, total area. Laboratory methods for preparing small thin film solar cells are evaporation, closed-space sublimation, closed-space vapor transport, vapor phase epitaxy and metallo-organic chemical vapor deposition, while economic large-area deposition techniques such as sputtering, glow discharge reduction, electrodeposition, spraying and screen printing are being used for module fabrication. The following aperture-area efficiencies have been measured, at the Solar Energy Research Inst., for thin film modules: a-Si:H, 9.8%, 933 cm{sup 2}; CuIn(Ga)Se{sub 2}, 11.1%, 938 cm{sup 2}; CdTe, 7.3%, 838 cm{sup 2}. The instability issue of a-Si:H continues to be a high priority area. It is necessary to improve the open-circuit voltage of CuIn(Ga)Se{sub 2} cells, which do not seem to exhibit any intrinsic degradation mechanisms. With continued progress and increased production, PV modules are likely to become competitive for medium-scale power requirements in the mid-1990s. (orig.).

  11. Surface morphology of thin films polyoxadiazoles

    OpenAIRE

    J. Weszka; M.M. Szindler; M. Chwastek-Ogierman; M. Bruma; P. Jarka; Tomiczek, B.

    2011-01-01

    urpose: The purpose of this paper was to analyse the surface morphology of thin films polyoxadiazoles. Design/methodology/approach: SSix different polymers which belong to the group of polyoxadiazoles were dissolved in the solvent NMP. Each of these polymer was deposited on a glass substrate and a spin coating method was applied with a spin speed of 1000, 2000 and 3000 rev/min. Changes in surface topography and roughness were observed. An atomic force microscope AFM Park System has been used....

  12. Amorphous silicon for thin-film transistors

    OpenAIRE

    Schropp, Rudolf Emmanuel Isidore

    1987-01-01

    Hydrogenated amorphous silicon (a-Si:H) has considerable potential as a semiconducting material for large-area photoelectric and photovoltaic applications. Moreover, a-Si:H thin-film transistors (TFT’s) are very well suited as switching devices in addressable liquid crystal display panels and addressable image sensor arrays, due to a new technology of low-cost, Iow-temperature processing overlarge areas. ... Zie: Abstract

  13. Fluxoid dynamics in superconducting thin film rings

    OpenAIRE

    Kirtley, J. R.; Tsuei, C. C.; Kogan, V. G.; Clem, J. R.; Raffy, H.; Li, Z. Z.

    2003-01-01

    We have measured the dynamics of individual magnetic fluxoids entering and leaving photolithographically patterned thin film rings of the underdoped high-temperature superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+\\delta}$, using a variable sample temperature scanning SQUID microscope. These results can be qualitatively described using a model in which the fluxoid number changes by thermally activated nucleation of a Pearl vortex in, and transport of the Pearl vortex across, the ring wall.

  14. Thin-film silicon solar cell technology

    Czech Academy of Sciences Publication Activity Database

    Shah, A. V.; Schade, H.; Vaněček, Milan; Meier, J.; Vallat-Sauvain, E.; Wyrsch, N.; Kroll, U.; Droz, C.; Bailat, J.

    2004-01-01

    Roč. 12, - (2004), s. 113-142. ISSN 1062-7995 R&D Projects: GA MŽP SN/320/11/03 Institutional research plan: CEZ:AV0Z1010914 Keywords : thin-film silicon modules * hydrogen erated amorphous silicon(a-Si:H) * hydrogen erated microcrystalline (ćc-Si:H) * transparent conductive oxydes(TCOs) * building-integrated photovoltaics(BIPV) Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.196, year: 2004

  15. Casimir force between atomically thin gold films

    OpenAIRE

    Boström, Mathias; Persson, Clas; Sernelius, Bo E.

    2013-01-01

    We have used density functional theory to calculate the anisotropic dielectric functions for ultrathin gold sheets (composed of 1, 3, 6, and 15 atomic layers). Such films are important components in nano-electromechanical systems. When using correct dielectric functions rather than bulk gold dielectric functions we predict an enhanced attractive Casimir-Lifshitz force (at most around 20%) between two atomically thin gold sheets. For thicker sheets the dielectric properties and the correspondi...

  16. The carbonization of thin polyaniline films

    Czech Academy of Sciences Publication Activity Database

    Morávková, Zuzana; Trchová, Miroslava; Exnerová, Milena; Stejskal, Jaroslav

    2012-01-01

    Roč. 520, č. 19 (2012), s. 6088-6094. ISSN 0040-6090 R&D Projects: GA AV ČR IAA400500905; GA AV ČR IAA100500902; GA ČR GAP205/12/0911 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : polyaniline * thin films * infrared spectroscopy Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.604, year: 2012

  17. Multiferroic behavior of templated BiFeO3-CoFe2O4 self-assembled nanocomposites.

    Science.gov (United States)

    Aimon, Nicolas M; Kim, Dong Hun; Sun, XueYin; Ross, C A

    2015-02-01

    Self-assembled BiFeO3-CoFe2O4 nanocomposites were templated into ordered structures in which the ferrimagnetic CoFe2O4 pillars form square arrays of periods 60-100 nm in a ferroelectric BiFeO3 matrix. The ferroelectricity, magnetism, conductivity, and magnetoelectric coupling of the ordered nanocomposites were characterized by scanning probe microscopy. The insulating BiFeO3 matrix exhibited ferroelectric domains, whereas the resistive CoFe2O4 pillars exhibited single-domain magnetic contrast with high anisotropy due to the magnetoelasticity of the spinel phase. Magnetoelectric coupling was observed in which an applied voltage led to reversal of the magnetic pillars. PMID:25559139

  18. Factors affecting surface and release properties of thin PDMS films

    DEFF Research Database (Denmark)

    Vudayagiri, Sindhu; Junker, Michael Daniel; Skov, Anne Ladegaard

    2013-01-01

    -strain in the films which affect the overall performance of the films. The current research is directed towards investigating factors affecting the peel force and release of thin, corrugated polydimethylsiloxane films used in DEAP films. It has been shown that doping the PDMS films with small quantities of...

  19. Titanium diffusion in gold thin films

    International Nuclear Information System (INIS)

    In the present study, diffusion phenomena in titanium/gold (Ti/Au) thin films occurring at temperatures ranging between 200 and 400 oC are investigated. The motivation is twofold: the first objective is to characterize Ti diffusion into Au layer as an effect of different heat-treatments. The second goal is to prove that the implementation of a thin titanium nitride (TiN) layer between Ti and Au can remarkably reduce Ti diffusion. It is observed that Ti atoms can fully diffuse through polycrystalline Au thin films (260 nm thick) already at temperatures as a low as 250 oC. Starting from secondary ion mass spectroscopy data, the overall diffusion activation energy ΔE = 0.66 eV and the corresponding pre-exponential factor D0 = 5 x 10-11 cm2/s are determined. As for the grain boundary diffusivity, both the activation energy range 0.54 gb 0Dgb0 = 1.14 x 10-8 cm2/s are obtained. Finally, it is observed that the insertion of a thin TiN layer (40 nm) between gold and titanium acts as an effective diffusion barrier up to 400 oC.

  20. Surface sensitive analysis of YBCO thin films

    International Nuclear Information System (INIS)

    Successful cleaning and polishing of a set of YBa2Cu3O7-δ(YBCO) thin films prepared by pulsed laser deposition (PLD) and chemical solution deposition (CSD) have been performed. The roughness of the films was reduced to a value of less than 5 nm, which opens a way to apply local surface sensitive techniques even on formerly very rough samples (some hundred nm peak-to-valley) such as CSD YBCO films. As one application flux lines of YBCO films were imaged with the omicron cryogenic SFM in MFM mode. The knowledge about geometry and distribution of artificial nanodefects in the interior of the film is crucial for further improvement of superconducting properties of these materials. The above mentioned polishing procedure has been further developed to prepare smooth low angle wedges of such samples. This offers the possibility to obtain depth dependent information with different surface sensitive scanning techniques. A high resolution electron backscattered diffraction image on the polished wedge of CSD YBCO sample reveals the homogeneous distribution of non superconducting BaHfO3 nanoparticles in the whole volume of the film

  1. Magnetic and ferroelectric characteristics of Gd$^{3+}$ and Ti$^{4+}$ co-doped BiFeO$_3$ ceramics

    Indian Academy of Sciences (India)

    SHIVANAND MADOLAPPA; A V ANUPAMA; P W JASCHIN; K B R VARMA; B SAHOO

    2016-04-01

    Polycrystalline BiFeO3 and Bi$_{0.9}$Gd$_{0.1}$Fe$_{1−x}$Ti$_x$O$_3$ ($x = 0$, 0.01, 0.05 and 0.1) samples were synthesized by solid-state reaction route. Structural, magnetic and ferroelectric properties of these samples were investigated. X-ray powder diffraction (XRD) results confirmed the presence of a significant amount of Bi$_2$Fe$_4$O$_9$ impurity phase in the undoped BiFeO$_3$ sample. Mössbauer spectroscopy studies corroborated the XRD studies to confirm the presence of impurity phase.We have observed that gadolinium (Gd$^{3+}$) and titanium (Ti$^{4+}$) doping, respectively, on Bi$^{3+}$ and Fe$^{3+}$ sites facilitated a significant reduction in the impurity phase formation in BiFeO$_3$. Interestingly, Gd$^{3+}$-doping significantly reduced the impurity phase formation as compared to the undoped BiFeO$_3$ sample. This impurity phase formation was further overcome by doping higher ($x \\ge 0.05$) amounts of Ti in BiFeO$_3$. The crystallographicsite occupancies of Gd and Ti were confirmed by Rietveld refinement of XRD data,Mössbauer spectroscopy and magnetization measurements. An enhancement in ferromagnetic properties along with moderate ferroelectricproperties have been observed after co-doping. There was an increasing trend in remnant polarization (Pr) with the increase in Ti concentration besides an improvement in the characteristic saturation magnetization. Our resultsdemonstrate that Gd$^{3+}$ and Ti$^{4+}$ doping could be used to enhance multifunctional properties of BiFeO3 ceramics to enable them as potential material for various devices.

  2. Thin Film Deposition Using Energetic Ions

    Directory of Open Access Journals (Sweden)

    Stephan Mändl

    2010-07-01

    Full Text Available One important recent trend in deposition technology is the continuous expansion of available processes towards higher ion assistance with the subsequent beneficial effects to film properties. Nowadays, a multitude of processes, including laser ablation and deposition, vacuum arc deposition, ion assisted deposition, high power impulse magnetron sputtering and plasma immersion ion implantation, are available. However, there are obstacles to overcome in all technologies, including line-of-sight processes, particle contaminations and low growth rates, which lead to ongoing process refinements and development of new methods. Concerning the deposited thin films, control of energetic ion bombardment leads to improved adhesion, reduced substrate temperatures, control of intrinsic stress within the films as well as adjustment of surface texture, phase formation and nanotopography. This review illustrates recent trends for both areas; plasma process and solid state surface processes.

  3. Supramolecular structure of electroactive polymer thin films

    Science.gov (United States)

    Kornilov, V. M.; Lachinov, A. N.; Karamov, D. D.; Nabiullin, I. R.; Kul'velis, Yu. V.

    2016-05-01

    This paper presents the results of an experimental investigation of the supramolecular structure of polydiphenylenephthalide thin films that exhibit effects of resistive switching. The supramolecular structure of the polymer has been investigated using small-angle neutron scattering in conjunction with atomic force microscopy. It has been found that the internal structure of polymer films consists of structural elements in the form of spheroids. The sizes of the structural elements, which were obtained from the neutron scattering data and analysis of the atomic force microscopy images, correlate well with each other. A model of the formation of polymer layers has been proposed. The observed structural elements in polymer films are formed due to the association of macromolecules in the initial polymer solution.

  4. Magnetization relaxation in sputtered thin permalloy films

    Science.gov (United States)

    Oliveira, R. C.; Rodríguez-Suárez, R. L.; Aguiar, F. M. De; Rezende, S. M.; Fermin, J. R.; Azevedo, A.

    2004-05-01

    In order to understand the underlying phenomena of magnetization damping in metallic thin films, samples of permalloy films were grown by magnetron sputtering, and their 8.6-GHz ferromagnetic resonance linewidth ΔH has been measured as a function of the Permalloy (Py) film thickness t, at room temperature. We made samples of Py(t)/Si(001) and X/Py(t)/X/Si(001), with X=Pd (40Å), and Cr (25Å), with 20Å < t < 200Å. While ΔH scales with t-2 in the bare Py/Si series, it is shown that the damping behavior strongly depends on X in the sandwich samples.

  5. Sulfated cellulose thin films with antithrombin affinity

    Directory of Open Access Journals (Sweden)

    2009-11-01

    Full Text Available Cellulose thin films were chemically modified by in situ sulfation to produce surfaces with anticoagulant characteristics. Two celluloses differing in their degree of polymerization (DP: CEL I (DP 215–240 and CEL II (DP 1300–1400 were tethered to maleic anhydride copolymer (MA layers and subsequently exposed to SO3•NMe3 solutions at elevated temperature. The impact of the resulting sulfation on the physicochemical properties of the cellulose films was investigated with respect to film thickness, atomic composition, wettability and roughness. The sulfation was optimized to gain a maximal surface concentration of sulfate groups. The scavenging of antithrombin (AT by the surfaces was determined to conclude on their potential anticoagulant properties.

  6. Irradiation effects in YBCO thin films

    International Nuclear Information System (INIS)

    Oxide superconductors are very sensitive to electron or ion beam irradiation/implantation. In the past 19 years after high-Tc (HTc) superconductivity was discovered in these materials, many aspects of interactions of accelerated particles with HTc thin films were investigated. In this paper short review of most significant phenomena is given, especially of those important for electronic applications (controllable reduction of critical temperature and critical current density) and their applications for HTc film patterning, fabrication of HTc Josephson junctions and SQUIDs. Some new results in creating 3-d inhomogeneous regions in YBCO superconductors by ion irradiation/implantation and investigation of high harmonic generation in YBCO film modified by 100 keV oxygen ions are presented. (author)

  7. Nanocrystalline silicon based thin film solar cells

    Science.gov (United States)

    Ray, Swati

    2012-06-01

    Amorphous silicon solar cells and panels on glass and flexible substrate are commercially available. Since last few years nanocrystalline silicon thin film has attracted remarkable attention due to its stability under light and ability to absorb longer wavelength portion of solar spectrum. For amorphous silicon/ nanocrystalline silicon double junction solar cell 14.7% efficiency has been achieved in small area and 13.5% for large area modules internationally. The device quality nanocrystalline silicon films have been fabricated by RF and VHF PECVD methods at IACS. Detailed characterizations of the materials have been done. Nanocrystalline films with low defect density and high stability have been developed and used as absorber layer of solar cells.

  8. Visible-light driven generation of reactive radicals over BiFeO3/TiO2 nanotube array: experimental evidence and energetic mechanism

    International Nuclear Information System (INIS)

    BiFeO3-based materials have attracted broad interests due to their multiferric and photoactive properties, but there remains some controversial uncertainty about the electronic structures of various nanoparticles of BiFeO3. In this work, BiFeO3 nanoparticles smaller than 100 nm have grown into TiO2 nanotube array by an ultrasonic-immersion method. Some evidences on the energy band position of BiFeO3 nanoparticles in BiFeO3/TiO2 nanotube array were from the visible-light driven photo responses. Positive surface photovoltage polarity of the composite is the same as that of the pure TiO2 nanotube array, which reveals the photo-induced electron transfer from BiFeO3 nanoparticles to TiO2 nanotubes. Furthermore, both ·OH and ·O2− radicals could be detected by the electron paramagnetic resonance (EPR) spin-trapping method. According to the EPR result, the valence band edge of BiFeO3 nanoparticles could be deduced as more positive than the potential at which ·OH radical could be generated. A scheme on the energy band alignment and photo-induced charges transfer processes is then proposed based on the observed visible-light photo activity of BiFeO3/TiO2 nanotube array

  9. Effect of Structural Transition on Magnetic Properties of Ca and Mn co-substituted BiFeO3 Ceramics

    OpenAIRE

    Kumar, Pawan; Kar, Manoranjan

    2014-01-01

    Composition-driven structural transitions in Bi1-xCaxFe1-xMnxO3 ceramics prepared by the tartaric acid modified sol-gel technique have been studied to analyze its effect on the magnetic properties of bismuth ferrite (BiFeO3). It was observed that the co-substitution of Ca & Mn at Bi & Fe sites in BiFeO3 (BFO) significantly suppress the impurity phases. The quantitative crystallographic phase analysis has been carried out by double phase Rietveld analysis of all the XRD patterns which indicate...

  10. Pr and Cr co-doped BiFeO3 nanotubes: an advance multiferroic oxide material

    OpenAIRE

    Mandal Kalyan; Gopal Khan Gobinda; Das Rajasree

    2013-01-01

    Arrays of single phase pure and Pr-Cr co-doped BiFeO3 (BFO) nanotubes (NTs) with compositions BiFeO3 and Bi0.9Pr0.1Fe0.9Cr0.1O3 have been synthesized using Anodic Aluminium Oxide (AAO) template (pore diameter ~250 nm) by wet chemical liquid phase deposition technique. All the NTs show ferromagnetic nature at room temperature (RT). Better magnetic properties are observed in the co-doped BFO NTs with the value of saturation magnetization (MS) ~49 memu/g, magnetization at the remanence (MR) ~12 ...

  11. Tailoring surface phase transition and magnetic behaviors in BiFeO3 via doping engineering.

    Science.gov (United States)

    Yan, Feng; Xing, Guozhong; Wang, Rongming; Li, Lin

    2015-01-01

    The charge-spin interactions in multiferroic materials (e.g., BiFeO3) have attracted enormous attention due to their high potential for next generation information electronics. However, the weak and deficient manipulation of charge-spin coupling notoriously limits their commercial applications. To tailor the spontaneous charge and the spin orientation synergistically in BiFeO3 (BFO), in this report, the 3d element of Mn doping engineering is employed and unveils the variation of surface phase transition and magnetic behaviors by introducing chemical strain. The spontaneous ferroelectric response and the corresponding domain structures, magnetic behaviors and spin dynamics in Mn-doped BFO ceramics have been investigated systematically. Both the surface phase transition and magnetization were enhanced in BFO via Mn doping. The interaction between the spontaneous polarization charge and magnetic spin reorientation in Mn-doped BFO are discussed in detail. Moreover, our extensive electron paramagnetic resonance (EPR) results demonstrate that the 3d dopant plays a paramount role in the surface phase transition, which provides an alternative route to tune the charge-spin interactions in multiferroic materials. PMID:25774619

  12. Structural and Ferroic Properties of La, Nd, and Dy Doped BiFeO3 Ceramics

    Directory of Open Access Journals (Sweden)

    Ashwini Kumar

    2015-01-01

    Full Text Available Polycrystalline samples of Bi0.8RE0.2FeO3 (RE = La, Nd, and Dy have been synthesized by solid-state reaction route. X-ray diffraction (XRD patterns of Bi0.8La0.2FeO3 and Bi0.8Nd0.2FeO3 were indexed in rhombohedral (R3c and triclinic (P1 structure, respectively. Rietveld refined XRD pattern of Bi0.8Dy0.2FeO3 confirms the biphasic (Pnma + R3c space groups nature. Raman spectroscopy reveals the change in BiFeO3 mode positions and supplements structural change with RE ion substitution. Ferroelectric and ferromagnetic loops have been observed in the Bi0.8RE0.2FeO3 ceramics at room temperature, indicating that ferroelectric and ferromagnetic ordering coexist in the ceramics at room temperature. The magnetic measurements at room temperature indicate that rare-earth substitution induces ferromagnetism and discerns large and nonzero remnant magnetization as compared to pristine BiFeO3.

  13. Scanning tunneling spectroscopy of Pb thin films

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Michael

    2010-12-13

    The present thesis deals with the electronic structure, work function and single-atom contact conductance of Pb thin films, investigated with a low-temperature scanning tunneling microscope. The electronic structure of Pb(111) thin films on Ag(111) surfaces is investigated using scanning tunneling spectroscopy (STS). Quantum size effects, in particular, quantum well states (QWSs), play a crucial role in the electronic and physical properties of these films. Quantitative analysis of the spectra yields the QWS energies as a function of film thickness, the Pb bulk-band dispersion in {gamma}-L direction, scattering phase shifts at the Pb/Ag interface and vacuum barrier as well as the lifetime broadening at anti {gamma}. The work function {phi} is an important property of surfaces, which influences catalytic reactivity and charge injection at interfaces. It controls the availability of charge carriers in front of a surface. Modifying {phi} has been achieved by deposition of metals and molecules. For investigating {phi} at the atomic scale, scanning tunneling microscopy (STM) has become a widely used technique. STM measures an apparent barrier height {phi}{sub a}, which is commonly related to the sample work function {phi}{sub s} by: {phi}{sub a}=({phi}{sub s}+{phi}{sub t}- vertical stroke eV vertical stroke)/2, with {phi}{sub t} the work function of the tunneling tip, V the applied tunneling bias voltage, and -e the electron charge. Hence, the effect of the finite voltage in STM on {phi}{sub a} is assumed to be linear and the comparison of {phi}{sub a} measured at different surface sites is assumed to yield quantitative information about work function differences. Here, the dependence of {phi}{sub a} on the Pb film thickness and applied bias voltage V is investigated. {phi}{sub a} is found to vary significantly with V. This bias dependence leads to drastic changes and even inversion of contrast in spatial maps of {phi}{sub a}, which are related to the QWSs in the Pb

  14. Preparation and characterization of vanadium oxide thin films

    International Nuclear Information System (INIS)

    The thermotropic VO2 films have many applications, since they exhibit semiconductor-conductor switching properties at temperature around 70 grad C. Vanadium oxide thin films were prepared via sol-gel method. Spin coater was used to depose these films on Si/SiO2 and lime glass substrates. Thin films of V2O5 can be reduced to metastable VO2 thin films at the temperature of 450 grad C under the pressure of 10-2 Pa. These films are then converted to thermotropic VO2 at 700 grad C in argon under normal pressure. (authors)

  15. Investigation of irradiated ferroelectric thin films

    International Nuclear Information System (INIS)

    Irradiation effects on highly oriented Pb1Zr0.53Ti0.47O3 (PZT), Pb0.94La0.06Zr0.65Ti0.35O3 (PLZT-6), and Pb1Zr1O3 (PZ) ferroelectric (FE) and antiferroelectric (AF) thin films are investigated with respect to their possible application as a temperature sensitive element in a new bolometer system for ITER. The PZT and PZ films were deposited by a sol-gel technique on a Pt/TiO2/Si substrate, whereas the PLZT-6 film was deposited by pulsed laser deposition (PLD) on a LSCO/MgO (100) substrate. The dielectric properties, i.e. the hysteresis loop and the dielectric constant of the films, were investigated in a frequency range from 20 Hz to 100 kHz and at temperatures up to 300 deg. C, before and after neutron irradiation to a fast neutron fluence of 5x1021m-2 (E>0.1MeV). The dielectric constant was measured during cooling with 2 deg. C.min-1. The dielectric properties of the films were measured before and after annealing to 300 deg. C. (author)

  16. Cerium Dioxide Thin Films Using Spin Coating

    Directory of Open Access Journals (Sweden)

    D. Channei

    2013-01-01

    Full Text Available Cerium dioxide (CeO2 thin films with varying Ce concentrations (0.1 to 0.9 M, metal basis were deposited on soda-lime-silica glass substrates using spin coating. It was found that all films exhibited the cubic fluorite structure after annealing at 500°C for 5 h. The laser Raman microspectroscopy and GAXRD analyses revealed that increasing concentrations of Ce resulted in an increase in the degree of crystallinity. FIB and FESEM images confirmed the laser Raman and GAXRD analyses results owing to the predicted increase in film thickness with increasing Ce concentration. However, porosity and shrinkage (drying cracking of the films also increased significantly with increasing Ce concentrations. UV-VIS spectrophotometry data showed that the transmission of the films decreased with increasing Ce concentrations due to the increasing crack formation. Furthermore, a red shift was observed with increasing Ce concentrations, which resulted in a decrease in the optical indirect band gap.

  17. Reactively sputtered Fe3O4-based films for spintronics

    International Nuclear Information System (INIS)

    Half metallic polycrystalline, epitaxial Fe3O4 films and Fe3O4-based heterostructures for spintronics were fabricated by DC reactive magnetron sputtering. Large tunneling magnetoresistance was found in the polycrystalline Fe3O4 films and attributed to the insulating grain boundaries. The pinning effect of the moments at the grain boundaries leads to a significant exchange bias. Frozen interfacial/surface moments induce weak saturation of the high-field magnetoresistance. The films show a moment rotation related butterfly-shaped magnetoresistance. It was found that in the films, natural growth defects, antiphase boundaries, and magnetocrystalline anisotropy play important roles in high-order anisotropic magnetoresistance. Spin injection from Fe3O4 films to semiconductive Si and ZnO was measured to be 45% and 28.5%, respectively. The positive magnetoresistance in the Fe3O4-based heterostructures is considered to be caused by a shift of the Fe3O4 eg ↑ band near the interface. Enhanced magnetization was observed in Fe3O4/BiFeO3 heterostructures experimentally and further proved by first principle calculations. The enhanced magnetization can be explained by spin moments of the thin BiFeO3 layer substantially reversing into a ferromagnetic arrangement under a strong coupling that is principally induced by electronic orbital reconstruction at the interface. (topical review - magnetism, magnetic materials and interdisciplinary research)

  18. Thin-liquid-film evaporation at contact line

    Institute of Scientific and Technical Information of China (English)

    Hao WANG; Zhenai PAN; Zhao CHEN

    2009-01-01

    When a liquid wets a solid wall, the extended meniscus near the contact line may be divided into three regions: a nonevaporating region, where the liquid is adsorbed on the wall; a transition region or thin-film region, where effects of long-range molecular forces (disjoining pressure) are felt; and an intrinsic meniscus region, where capillary forces dominate. The thin liquid film, with thickness from nanometers up to micrometers, covering the transition region and part of intrinsic meniscus, is gaining interest due to its high heat transfer rates. In this paper, a review was made of the researches on thin-liquid-film evaporation. The major characteristics of thin film, thin-film modeling based on continuum theory, simulations based on molecular dynamics, and thin-film profile and temperature measurements were summarized.

  19. Theoretical investigation of the thermodynamic properties of metallic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hung, Vu Van [Vietnam Education Publishing House, 81 Tran Hung Dao, Hanoi (Viet Nam); Phuong, Duong Dai [Hanoi National University of Education, 136 Xuan Thuy, Hanoi (Viet Nam); Hoa, Nguyen Thi [University of Transport and Communications, Lang Thuong, Dong Da, Hanoi (Viet Nam); Hieu, Ho Khac, E-mail: hieuhk@duytan.edu.vn [Institute of Research and Development, Duy Tan University, K7/25 Quang Trung, Danang (Viet Nam)

    2015-05-29

    The thermodynamic properties of metallic thin films with face-centered cubic structure at ambient conditions were investigated using the statistical moment method including the anharmonicity effects of thermal lattice vibrations. The analytical expressions of Helmholtz free energy, lattice parameter, linear thermal expansion coefficient, specific heats at the constant volume and constant pressure were derived in terms of the power moments of the atomic displacements. Numerical calculations of thermodynamic properties have been performed for Au and Al thin films and compared with those of bulk metals. This research proposes that thermodynamic quantities of thin films approach the values of bulk when the thickness of thin film is about 70 nm. - Highlights: • Thermodynamic properties of thin films were investigated using the moment method. • Expressions of Helmholtz energy, expansion coefficient, specific heats were derived. • Calculations for Au, Al thin films were performed and compared with those of bulks.

  20. Theoretical investigation of the thermodynamic properties of metallic thin films

    International Nuclear Information System (INIS)

    The thermodynamic properties of metallic thin films with face-centered cubic structure at ambient conditions were investigated using the statistical moment method including the anharmonicity effects of thermal lattice vibrations. The analytical expressions of Helmholtz free energy, lattice parameter, linear thermal expansion coefficient, specific heats at the constant volume and constant pressure were derived in terms of the power moments of the atomic displacements. Numerical calculations of thermodynamic properties have been performed for Au and Al thin films and compared with those of bulk metals. This research proposes that thermodynamic quantities of thin films approach the values of bulk when the thickness of thin film is about 70 nm. - Highlights: • Thermodynamic properties of thin films were investigated using the moment method. • Expressions of Helmholtz energy, expansion coefficient, specific heats were derived. • Calculations for Au, Al thin films were performed and compared with those of bulks

  1. Investigating the interfacial dynamics of thin films

    Science.gov (United States)

    Rosenbaum, Aaron W.

    This thesis probes the interfacial dynamics and associated phenomena of thin films. Surface specific tools were used to study the self-assembly of alkanethiols, the mono- and bilayer dynamics of SF6, and the surface motion of poly(methyl methacrylate). Non-pertubative helium atom scattering was the principal technique used to investigate these systems. A variety of other complementary tools, including scanning tunneling microscopy, electron diffraction, Auger spectroscopy, atomic force microscopy, and ellipsometry were used in tandem with the neutral atom scattering studies. Controlling the spontaneous assembly of alkanethiols on Au(111) requires a better fundamental understanding of the adsorbate-adsorbate and substrate-adsorbate interactions. Our characterization focused on two key components, the surface structure and adsorbate vibrations. The study indicates that the Au(111) reconstruction plays a larger role than anticipated in the low-density phase of alkanethiol monolayers. A new structure is proposed for the 1-decanethiol monolayer that impacts the low-energy vibrational mode. Varying the alkane chain lengths imparts insight into the assembly process via characterization of a dispersionless phonon mode. Studies of SF6 physisorbed on Au(111) bridge surface research on rare gas adsorbates with complicated dynamical organic thin films. Mono- and bilayer coverages of SF6/Au(111) were studied at cryogenic temperatures. Our experiments probed the surface properties of SF6 yielding insights into substrate and coverage effects. The study discovered a dispersionless Einstein oscillation with multiple harmonic overtones. A second layer of SF6 softened the mode, but did not show any indications of bulk or cooperative interactions. The vibrational properties of SF 6 showed both striking similarities and differences when compared with physisorbed rare gases. Lastly, this thesis will discuss studies of thin film poly(methyl methacrylate) on Si. The non-pertubative and

  2. Pulsed laser deposition of pepsin thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kecskemeti, G. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary)]. E-mail: kega@physx.u-szeged.hu; Kresz, N. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary); Smausz, T. [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary); Hopp, B. [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary); Nogradi, A. [Department of Ophthalmology, University of Szeged, H-6720, Szeged, Koranyi fasor 10-11 (Hungary)

    2005-07-15

    Pulsed laser deposition (PLD) of organic and biological thin films has been extensively studied due to its importance in medical applications among others. Our investigations and results on PLD of a digestion catalyzing enzyme, pepsin, are presented. Targets pressed from pepsin powder were ablated with pulses of an ArF excimer laser ({lambda} = 193 nm, FWHM = 30 ns), the applied fluence was varied between 0.24 and 5.1 J/cm{sup 2}. The pressure in the PLD chamber was 2.7 x 10{sup -3} Pa. The thin layers were deposited onto glass and KBr substrates. Our IR spectroscopic measurements proved that the chemical composition of deposited thin films is similar to that of the target material deposited at 0.5 and 1.3 J/cm{sup 2}. The protein digesting capacity of the transferred pepsin was tested by adapting a modified 'protein cube' method. Dissolution of the ovalbumin sections proved that the deposited layers consisted of catalytically active pepsin.

  3. Memristive switching in vanadium dioxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Buerger, Danilo; John, Varun; Kovacs, Gyoergy; Skorupa, Ilona; Helm, Manfred; Schmidt, Heidemarie [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany)

    2011-07-01

    Memristive devices exhibit an improved performance at ultra-small scales. The microscopic model for memristive behavior in oxide nanostructures often depends on the distribution of oxygen vacancies and is determined by the cation species. In 2008 HP presented the first bipolar TiO2-based memristor for resistive applications, where the drift of oxygen vacancies causes a change in the resistance of ultrathin TiO2 films which can be locally modified by ion implantation. We prepared vanadium dioxide (VO2) thin films with the reversible metal-insulator phase transition at the thermochromic switching temperature of around 340 K by pulsed laser deposition on (0001)-sapphire substrates and analyzed the electric-pulse-induced thermochromic switching in the VO2 gap region at room temperature due to local heating. As a result, we find the typical pinched hysteresis loop of a memristor, a repeatable switching behavior for billions of voltage pulses and switching times shorter than 50 ns in VO2 thin films.

  4. Powdering characteristics of thin film evaporator, 1

    International Nuclear Information System (INIS)

    Vertical thin film evaporators have been used to concentrate and dry solutions because their rotating swing blades prevent scale from being deposited on the heated surfaces. Powdering capacity of the vertical thin film evaporator was examined experimentally for drying applications of radioactive liquid waste generated from nuclear power plants. As a result, it was found that the powdering capacity increased with the blade rotation, changing significantly in the low ratational region and scarcely in the high rotational region. The powdering capacity in the high rotational region was restricted by the lack of heat flux which was theoretically evaluated for the concentrating process. As the critical factor in the low rotational region was not clear, a visual test apparatus was made to observe flow patterns in the evaporator, and a powdering model was obtained. This model showed that powdering process was obstructed when the liquid film lost its fluidity at high concentration. Based on this model, the powdering process was simulated theoretically with good agreement between calculated and experimental results. (author)

  5. Polarized Neutron Reflectivity Simulation of Ferromagnet/ Antiferromagnet Thin Films

    International Nuclear Information System (INIS)

    This report investigates the current simulating and fitting programs capable of calculating the polarized neutron reflectivity of the exchange-biased ferromagnet/antiferromagnet magnetic thin films. The adequate programs are selected depending on whether nonspin flip and spin flip reflectivities of magnetic thin films and good user interface are available or not. The exchange-biased systems such as Fe/Cr, Co/CoO, CoFe/IrMn/Py thin films have been simulated successfully with selected programs

  6. Overview and Challenges of Thin Film Solar Electric Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Ullal, H. S.

    2008-12-01

    In this paper, we report on the significant progress made worldwide by thin-film solar cells, namely, amorphous silicon (a-Si), cadmium telluride (CdTe), and copper indium gallium diselenide (CIGS). Thin-film photovoltaic (PV) technology status is also discussed in detail. In addition, R&D and technology challenges in all three areas are elucidated. The worldwide estimated projection for thin-film PV technology production capacity announcements are estimated at more than 5000 MW by 2010.

  7. Networking Behavior in Thin Film and Nanostructure Growth Dynamics

    OpenAIRE

    Yuksel, Murat; Karabacak, Tansel; Guclu, Hasan

    2007-01-01

    Thin film coatings have been essential in development of several micro and nano-scale devices. To realize thin film coatings various deposition techniques are employed, each yielding surface morphologies with different characteristics of interest. Therefore, understanding and control of the surface growth is of great interest. In this paper, we devise a novel network-based modeling of the growth dynamics of such thin films and nano-structures. We specifically map dynamic steps taking place du...

  8. Orientation control and domain structure analysis of {100}-oriented epitaxial ferroelectric orthorhombic HfO2-based thin films

    Science.gov (United States)

    Katayama, Kiliha; Shimizu, Takao; Sakata, Osami; Shiraishi, Takahisa; Nakamura, Shogo; Kiguchi, Takanori; Akama, Akihiro; Konno, Toyohiko J.; Uchida, Hiroshi; Funakubo, Hiroshi

    2016-04-01

    Orientation control of {100}-oriented epitaxial orthorhombic 0.07YO1.5-0.93HfO2 films grown by pulsed laser deposition was investigated. To achieve in-plane lattice matching, indium tin oxide (ITO) and yttria-stabilized zirconia (YSZ) were selected as underlying layers. We obtained (100)- and (001)/(010)-oriented films on ITO and YSZ, respectively. Ferroelastic domain formation was confirmed for both films by X-ray diffraction using the superlattice diffraction that appeared only for the orthorhombic symmetry. The formation of ferroelastic domains is believed to be induced by the tetragonal-orthorhombic phase transition upon cooling the films after deposition. The present results demonstrate that the orientation of HfO2-based ferroelectric films can be controlled in the same manner as that of ferroelectric films composed of conventional perovskite-type material such as Pb(Zr, Ti)O3 and BiFeO3.

  9. Characterizations of photoconductivity of graphene oxide thin films

    Directory of Open Access Journals (Sweden)

    Shiang-Kuo Chang-Jian

    2012-06-01

    Full Text Available Characterizations of photoresponse of a graphene oxide (GO thin film to a near infrared laser light were studied. Results showed the photocurrent in the GO thin film was cathodic, always flowing in an opposite direction to the initial current generated by the preset bias voltage that shows a fundamental discrepancy from the photocurrent in the reduced graphene oxide thin film. Light illumination on the GO thin film thus results in more free electrons that offset the initial current. By examining GO thin films reduced at different temperatures, the critical temperature for reversing the photocurrent from cathodic to anodic was found around 187°C. The dynamic photoresponse for the GO thin film was further characterized through the response time constants within the laser on and off durations, denoted as τon and τoff, respectively. τon for the GO thin film was comparable to the other carbon-based thin films such as carbon nanotubes and graphenes. τoff was, however, much larger than that of the other's. This discrepancy was attributable to the retardation of exciton recombination rate thanks to the existing oxygen functional groups and defects in the GO thin films.

  10. Sputtering materials for VLSI and thin film devices

    CERN Document Server

    Sarkar, Jaydeep

    2010-01-01

    An important resource for students, engineers and researchers working in the area of thin film deposition using physical vapor deposition (e.g. sputtering) for semiconductor, liquid crystal displays, high density recording media and photovoltaic device (e.g. thin film solar cell) manufacturing. This book also reviews microelectronics industry topics such as history of inventions and technology trends, recent developments in sputtering technologies, manufacturing steps that require sputtering of thin films, the properties of thin films and the role of sputtering target performance on overall p

  11. Growth and Characterization of Epitaxial Oxide Thin Films

    OpenAIRE

    Garg, Ashish

    2001-01-01

    Epitaxial oxide thin films are used in many technologically important device applications. This work deals with the deposition and characterization of epitaxial WO3 and SrBi2Ta2O9 (SBT) thin films on single crystal oxide substrates. WO3 thin films were chosen as a subject of study because of recent findings of superconductivity at surfaces and twin boundaries in the bulk form of this oxide. Highly epitaxial thin films would be desirable in order to be able to create a device withi...

  12. Applications of thin-film photovoltaics for space

    Science.gov (United States)

    Landis, Geoffrey A.; Hepp, Aloysius F.

    1991-01-01

    The authors discuss the potential applications of thin-film polycrystalline and amorphous cells for space. There have been great advances in thin-film solar cells for terrestrial applications. Transfer of this technology to space applications could result in ultra low-weight solar arrays with potentially large gains in specific power. Recent advances in thin-film solar cells are reviewed, including polycrystalline copper indium selenide and related I-III-VI2 compounds, polycrystalline cadmium telluride and related II-VI compounds, and amorphous silicon arrays. The possibility of using thin-film multi-bandgap cascade solar cells is discussed.

  13. Thin-Film Photovoltaics: Status and Applications to Space Power

    Science.gov (United States)

    Landis, Geoffrey A.; Hepp, Aloysius F.

    1991-01-01

    The potential applications of thin film polycrystalline and amorphous cells for space are discussed. There have been great advances in thin film solar cells for terrestrial applications; transfer of this technology to space applications could result in ultra low weight solar arrays with potentially large gains in specific power. Recent advances in thin film solar cells are reviewed, including polycrystalline copper iridium selenide and related I-III-VI2 compounds, polycrystalline cadmium telluride and related II-VI compounds, and amorphous silicon alloys. The possibility of thin film multi bandgap cascade solar cells is discussed.

  14. Design and Simulation of the Thin Film Pulse Transformer

    Institute of Scientific and Technical Information of China (English)

    LIU Bao-yuan; SHI Yu; WEN Qi-ye

    2005-01-01

    A new thin film pulse transformer for using in ISND and ADSL systems has been designed based on a domain wall pinning model, the parameters of nano-magnetic thin film such as permeability and coercivity can be calculated. The main properties of the thin film transformer including the size,parallel inductance, Q value and turn ratio have been simulated and optimized. Simulation results show that the thin film transformer can be fairly operated in a frequency range of 0. 001~20 MHz.

  15. Physics of thin films advances in research and development

    CERN Document Server

    Hass, Georg; Vossen, John L

    2013-01-01

    Physics of Thin Films: Advances in Research and Development, Volume 12 reviews advances that have been made in research and development concerning the physics of thin films. This volume covers a wide range of preparative approaches, physics phenomena, and applications related to thin films. This book is comprised of four chapters and begins with a discussion on metal coatings and protective layers for front surface mirrors used at various angles of incidence from the ultraviolet to the far infrared. Thin-film materials and deposition conditions suitable for minimizing reflectance changes with

  16. Role of asphaltenes in stabilizing thin liquid emulsion films.

    Science.gov (United States)

    Tchoukov, Plamen; Yang, Fan; Xu, Zhenghe; Dabros, Tadeusz; Czarnecki, Jan; Sjöblom, Johan

    2014-03-25

    Drainage kinetics, thickness, and stability of water-in-oil thin liquid emulsion films obtained from asphaltenes, heavy oil (bitumen), and deasphalted heavy oil (maltenes) diluted in toluene are studied. The results show that asphaltenes stabilize thin organic liquid films at much lower concentrations than maltenes and bitumen. The drainage of thin organic liquid films containing asphaltenes is significantly slower than the drainage of the films containing maltenes and bitumen. The films stabilized by asphaltenes are much thicker (40-90 nm) than those stabilized by maltenes (∼10 nm). Such significant variation in the film properties points to different stabilization mechanisms of thin organic liquid films. Apparent aging effects, including gradual increase of film thickness, rigidity of oil/water interface, and formation of submicrometer size aggregates, were observed for thin organic liquid films containing asphaltenes. No aging effects were observed for films containing maltenes and bitumen in toluene. The increasing stability and lower drainage dynamics of asphaltene-containing thin liquid films are attributed to specific ability of asphaltenes to self-assemble and form 3D network in the film. The characteristic length of stable films is well beyond the size of single asphaltene molecules, nanoaggregates, or even clusters of nanoaggregates reported in the literature. Buildup of such 3D structure modifies the rheological properties of the liquid film to be non-Newtonian with yield stress (gel like). Formation of such network structure appears to be responsible for the slower drainage of thin asphaltenes in toluene liquid films. The yield stress of liquid film as small as ∼10(-2) Pa is sufficient to stop the drainage before the film reaches the critical thickness at which film rupture occurs. PMID:24564447

  17. Atomic Structure Control of Silica Thin Films on Pt(111)

    KAUST Repository

    Crampton, Andrew S

    2015-05-27

    Metal oxide thin films grown on metal single crystals are commonly used to model heterogeneous catalyst supports. The structure and properties of thin silicon dioxide films grown on metal single crystals have only recently been thoroughly characterized and their spectral properties well established. We report the successful growth of a three- dimensional, vitreous silicon dioxide thin film on the Pt(111) surface and reproduce the closed bilayer structure previously reported. The confirmation of the three dimensional nature of the film is unequivocally shown by the infrared absorption band at 1252 cm−1. Temperature programmed desorption was used to show that this three-dimensional thin film covers the Pt(111) surface to such an extent that its application as a catalyst support for clusters/nanoparticles is possible. The growth of a three-dimensional film was seen to be directly correlated with the amount of oxygen present on the surface after the silicon evaporation process. This excess of oxygen is tentatively attributed to atomic oxygen being generated in the evaporator. The identification of atomic oxygen as a necessary building block for the formation of a three-dimensional thin film opens up new possibilities for thin film growth on metal supports, whereby simply changing the type of oxygen enables thin films with different atomic structures to be synthesized. This is a novel approach to tune the synthesis parameters of thin films to grow a specific structure and expands the options for modeling common amorphous silica supports under ultra high vacuum conditions.

  18. Modelling the tribology of thin film interfaces

    CERN Document Server

    Zugic, R

    2000-01-01

    substrate). Within each group of simulations, three lubricant film thicknesses are studied to examine the effect of varying lubricant thickness. Statistical data are collected from each simulation and presented in this work. Via these data, together with the evolution, of atomic and molecular configurations, a very detailed picture of the properties of this thin film interface is presented. In particular, we conclude that perfluoropolyether lubricant forms distinct molecular layers when confined between two substrates, the rate of heat generation under shearing conditions typical of those in a head-disk interface is insufficient for thermal mechanisms to result directly in lubricant degradation, and mechanical stresses attained in the head-disk interface are unlikely to result in any significant degree of lubricant degradation. This thesis examines the tribology of a head-disk interface in an operating hard disk drive via non-equilibrium molecular dynamics computer simulations. The aim of this work is to deri...

  19. Electrical Resistance Tomography of Conductive Thin Films

    CERN Document Server

    Cultrera, Alessandro

    2016-01-01

    The Electrical Resistance Tomography (ERT) technique is applied to the measurement of sheet conductance maps of both uniform and patterned conductive thin films. Images of the sheet conductance spatial distribution, and local conductivity values are obtained. Test samples are tin oxide films on glass substrates, with electrical contacts on the sample boundary, some samples are deliberately patterned in order to induce null conductivity zones of known geometry while others contain higher conductivity inclusions. Four-terminal resistance measurements among the contacts are performed with a scanning setup. The ERT reconstruction is performed by a numerical algorithm based on the total variation regularization and the L-curve method. ERT correctly images the sheet conductance spatial distribution of the samples. The reconstructed conductance values are in good quantitative agreement with independent measurements performed with the van der Pauw and the four-point probe methods.

  20. Levan nanostructured thin films by MAPLE assembling.

    Science.gov (United States)

    Sima, Felix; Mutlu, Esra Cansever; Eroglu, Mehmet S; Sima, Livia E; Serban, Natalia; Ristoscu, Carmen; Petrescu, Stefana M; Oner, Ebru Toksoy; Mihailescu, Ion N

    2011-06-13

    Synthesis of nanostructured thin films of pure and oxidized levan exopolysaccharide by matrix-assisted pulsed laser evaporation is reported. Solutions of pure exopolysaccharides in dimethyl sulfoxide were frozen in liquid nitrogen to obtain solid cryogenic pellets that have been used as targets in pulsed laser evaporation experiments with a KrF* excimer source. The expulsed material was collected and assembled onto glass slides and Si wafers. The contact angle studies evidenced a higher hydrophilic behavior in the case of oxidized levan structures because of the presence of acidic aldehyde-hydrogen bonds of the coating formed after oxidation. The obtained films preserved the base material composition as confirmed by Fourier transform infrared spectroscopy. They were compact with high specific surface areas, as demonstrated by scanning electron and atomic force microscopy investigations. In vitro colorimetric assays revealed a high potential for cell proliferation for all coatings with certain predominance for oxidized levan. PMID:21520921

  1. Analysis on mechanism of thin film lubrication

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chaohui; LUO Jianbin; HUANG Zhiqiang

    2005-01-01

    It is an important concern to explore the properties and principles of lubrication at nano or molecularscale. For a long time, measurement apparatus for filmthickness of thin film lubrication (TFL) at nano scale havebeen devised on the basis of superthin interferometry technique. Many experiments were carried out to study the lubrication principles of TFL by taking advantages of aforementioned techniques, in an attempt to unveil the mechanism of TFL. Comprehensive experiments were conducted to explore the distinctive characteristics of TFL. Results show that TFL is a distinctive lubrication state other than any known lubrication ones, and serves as a bridge between elastohydrodynamic lubrication (EHL) and boundary lubrication (BL). Two main influence factors of TFL are the solid surface effects and the molecular properties of the lubricant, whose combination effects result in alignment of liquid molecules near the solid surfaces and subsequently lubrication with ordered film emerged. Results of theoretical analysis considering microstructure are consistent with experimental outcomes, thus validating the proposed mechanism.

  2. Separation Efficiency of Thin-film Evaporators

    Institute of Scientific and Technical Information of China (English)

    R.Billet

    2004-01-01

    The recovery of contaminants and useful substances from liquid wastes, the purification of production effluents and the separation of thermally instable mixtures are some of the multivarious applications of thin-film distillors in many processes of the chemical and allied industries and of the food industries. In a study carried out in pilot plants with distillation test systems there was found a good agreement between the experimental separation results and those obtained by computing with a theorectical model; the latter is based on the assumption of phase equilibrium between the vapour formed on an infinitely small element of area in a liquid film of any given concentric periphery of the vertically arranged evaporator. These tests were perfomed under various phase loads.

  3. Thermoviscoelastic models for polyethylene thin films

    Science.gov (United States)

    Li, Jun; Kwok, Kawai; Pellegrino, Sergio

    2016-02-01

    This paper presents a constitutive thermoviscoelastic model for thin films of linear low-density polyethylene subject to strains up to yielding. The model is based on the free volume theory of nonlinear thermoviscoelasticity, extended to orthotropic membranes. An ingredient of the present approach is that the experimentally inaccessible out-of-plane material properties are determined by fitting the model predictions to the measured nonlinear behavior of the film. Creep tests, uniaxial tension tests, and biaxial bubble tests are used to determine the material parameters. The model has been validated experimentally, against data obtained from uniaxial tension tests and biaxial cylindrical tests at a wide range of temperatures and strain rates spanning two orders of magnitude.

  4. Thin-film optical shutter. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Matlow, S.L.

    1981-02-01

    A specific embodiment of macroconjugated macromolecules, the poly (p-phenylene)'s, has been chosen as the one most likely to meet all of the requirements of the Thin Film Optical Shutter project (TFOS). The reason for this choice is included. In order to be able to make meaningful calculations of the thermodynamic and optical properties of the poly (p-phenylene)'s a new quantum mechanical method was developed - Equilibrium Bond Length (EBL) Theory. Some results of EBL Theory are included.

  5. Thin Film Photovoltaics: Markets and Industry

    OpenAIRE

    Arnulf Jäger-Waldau

    2012-01-01

    Since 2000, total PV production increased almost by two orders of magnitude, with a compound annual growth rate of over 52%. The most rapid growth in annual cell and module production over the last five years could be observed in Asia, where China and Taiwan together now account for about 60% of worldwide production. Between 2005 and 2009, thin film production capacity and volume increased more than the overall industry but did not keep up in 2010 and 2011 due to the rapid price decline for s...

  6. Fabrication of Optical Tunable Helical Thin Films

    Institute of Scientific and Technical Information of China (English)

    Linxin Hu; Peng Wang; Xingyang Wan; Shaoji Jiang

    2012-01-01

    Circular polarization selection of light is an important property of helical micro-nanostructure. The helical thin films fabricated by glancing angle deposition can provide both circular polarization selection and wavelength tuning in this work. Their selective transmissions were depicted in calculations and experiments. The wave- length tuning mechanism was revealed as the relationship between peak wavelength and deposition parameters. Therefore, tunable circular polarization components can be designed according to the mechanism mentioned above and fabricated by glancing angle deposition techniques. Potential applications include tunable optical filters, optical pulse-shapers, biosensors etc.

  7. Stable localized patterns in thin liquid films

    Science.gov (United States)

    Deissler, Robert J.; Oron, Alexander

    1992-01-01

    A two-dimensional nonlinear evolution equation is studied which describes the three-dimensional spatiotemporal behavior of the air-liquid interface of a thin liquid film lying on the underside of a cooled horizontal plate. It is shown that the equation has a Liapunov functional, and this fact is exploited to demonstrate that the Marangoni effect can stabilize the destabilizing effect of gravity (the Rayleigh-Taylor instability), allowing for the existence of stable localized axisymmetric solutions for a wide range of parameter values. Various properties of these structures are discussed.

  8. Birefringent thin films and polarizing elements

    CERN Document Server

    Hodgkinson, Ian J

    1997-01-01

    This book describes the propagation of light in biaxial media, the properties of biaxial thin films, and applications such as birefringent filters for tuning the wavelength of dye lasers.A novel feature of the first part is the parallel treatment of Stokes, Jones, and Berreman matrix formalisms in a chapter-by-chapter development of wave equations, basis vectors, transfer matrices, reflection and transmission equations, and guided waves. Computational tools for MATLAB are included.The second part focuses on an emerging planar technology in which anisotropic microstructures are formed by obliqu

  9. Mechanical properties of optical thin films

    Czech Academy of Sciences Publication Activity Database

    Tomáštík, J.; Čtvrtlík, R.; Šebestová, Hana; Schovánek, Petr; Jankůj, J.; Hrabovský, Miroslav

    Prague : ČVUT Technical University in Prague, 2012 - (Růžička, M.; Doubrava, K.; Horák, Z.), s. 469-476 ISBN 978-80-01-05060-6. [EAN 2012 - 50th Annual Conference on Experimental Stress Analysis. Tábor (CZ), 04.06.2012-07.06.2012] R&D Projects: GA TA ČR TA01010517 Institutional research plan: CEZ:AV0Z10100522 Keywords : thin films * mechanical properties * nanoindentation * scratch test Subject RIV: BH - Optics, Masers, Lasers

  10. Experiments of MAPLE thin film technology

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Miroslav; Kocourek, Tomáš; Remsa, Jan; Cristescu, R.; Mihailescu, I. N.; Dybal, Jiří; Pleštil, Josef

    Bellingham: SPIE, 2007 - (Atanasov, P.; Dreischuh, T.; Gateva, S.; Kovachev, L.), 6604OU/1-6604OU/7. (Proceedings of SPIE. 6604). ISBN 978-0-8194-6742-3. [International School on Quantum Electronics /14./. Sunny Beach (BG), 18.09.2006-22.09.2006] R&D Projects: GA ČR GA202/06/0216 Institutional research plan: CEZ:AV0Z10100522; CEZ:AV0Z40500505 Keywords : organic molecules * thin film s * PLD * MAPLE Subject RIV: BH - Optics, Masers, Lasers

  11. Optical and Nonlinear Optical Response of Light Sensor Thin Films

    OpenAIRE

    Weisz, S.Z.; O. Resto; Fonseca, F; Fernandez, L. F.E.; Vikhnin, V. S.; O. Vasquez; A. J. Rua; H. Liu

    2005-01-01

    For potential ultrafast optical sensor application, both VO2 thin films and nanocomposite crystal-Si enriched SiO2 thin films grown on fused quartz substrates were successfully prepared using pulsed laser deposition (PLD) and RF co-sputtering techniques. In photoluminescence (PL) measurement c-Si/SiO2 film contains nanoparticles of crystal Si exhibits strong red emission with the band maximum ranging from 580 to 750 nm. With ultrashort pulsed laser excitation all films show extremely intense ...

  12. High power impulse magnetron sputtering of CIGS thin films for high efficiency thin film solar cells

    Czech Academy of Sciences Publication Activity Database

    Olejníček, Jiří; Hubička, Zdeněk; Kohout, Michal; Kšírová, Petra; Kment, Štěpán; Brunclíková, Michaela; Čada, Martin; Darveau, S.A.; Exstrom, C.L.

    2014-01-01

    Roč. 1, č. 3 (2014), s. 135-137. ISSN 2336-2626 R&D Projects: GA MŠk LH12045 Institutional support: RVO:68378271 Keywords : CIGS * HiPIMS * emission spectroscopy * thin films * magnetron sputtering Subject RIV: BL - Plasma and Gas Discharge Physics http://fyzika.feld.cvut.cz/misc/ppt/articles/2014/olejnicek.pdf

  13. Nitrogen incorporation in sputter deposited molybdenum nitride thin films

    International Nuclear Information System (INIS)

    In this paper, the authors report on the high temperature performance of sputter deposited molybdenum (Mo) and molybdenum nitride (Mo2N) thin films. Various argon and nitrogen gas compositions are applied for thin film synthetization, and the amount of nitrogen incorporation is determined by Auger measurements. Furthermore, effusion measurements identifying the binding conditions of the nitrogen in the thin film are performed up to 1000 °C. These results are in excellent agreement with film stress and scanning electron microscope analyses, both indicating stable film properties up to annealing temperatures of 500 °C

  14. Nitrogen incorporation in sputter deposited molybdenum nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Stöber, Laura, E-mail: laura.stoeber@tuwien.ac.at; Patocka, Florian, E-mail: florian.patocka@tuwien.ac.at; Schneider, Michael, E-mail: michael.schneider@tuwien.ac.at; Schmid, Ulrich, E-mail: ulrich.e366.schmid@tuwien.ac.at [Institute of Sensor and Actuator Systems, TU Wien, Gußhausstraße 27-29, A-1040 Vienna (Austria); Konrath, Jens Peter, E-mail: jenspeter.konrath@infineon.com; Haberl, Verena, E-mail: verena.haberl@infineon.com [Infineon Technologies Austria AG, Siemensstraße 2, 9500 Villach (Austria)

    2016-03-15

    In this paper, the authors report on the high temperature performance of sputter deposited molybdenum (Mo) and molybdenum nitride (Mo{sub 2}N) thin films. Various argon and nitrogen gas compositions are applied for thin film synthetization, and the amount of nitrogen incorporation is determined by Auger measurements. Furthermore, effusion measurements identifying the binding conditions of the nitrogen in the thin film are performed up to 1000 °C. These results are in excellent agreement with film stress and scanning electron microscope analyses, both indicating stable film properties up to annealing temperatures of 500 °C.

  15. High Tc thin film and device development

    Energy Technology Data Exchange (ETDEWEB)

    Betts, K.; Burbank, M.B.; Cragg, A.; Fife, A.A.; Kubik, P.R.; Lee, S.; Chaklader, A.C.D.; Roemer, G.; Heinrich, B.; Chrzanowski, J.

    1989-03-01

    Thin films of the high Tc superconductor YBa/sub 2/Cu/sub 3/O/sub y/ have been deposited on various substrates by diode and magnetron sputtering using bulk sintered targets. These films have been analyzed by a variety of methods - SEM, X-rays, Electron Beam Microprobe, Mass Spectrometry and Raman Spectroscopy. The stoichiometries of the films have been measured as a function of the radial position from the centre of the sputtered beam at a fixed target-substrate distance. Patterning of the films has been carried out to form planar structures such as strip lines, microbridges and RF SQUIDs. DC current-voltage characteristics of the microbridges were measured as a function of temperature. RF SQUID behaviour has been observed for single loop devices and their properties established at 4.2 K and higher temperatures. Flux locked noise spectra with a 1/f noise power response were recorded in the frequency range 0.01 to approx.100 Hz. RF SQUID signals have been observed for temperatures up to 55 K.

  16. CLSM and UV-VIS researches on polyoxadiazoles thin films

    Directory of Open Access Journals (Sweden)

    J. Weszka

    2012-06-01

    Full Text Available Purpose: The purpose of this paper was to analyse the surface morphology and optical properties of polyoxadiazoles thin films.Design/methodology/approach: A few different conducting polymers were dissolved in N-methyl-2-pyrrolid(inone. Then the solutions were deposited on a glass substrate by spin coating method with a different spin rate. Changes in surface topography and optical properties were observed. A confocal laser scanning microscope CLSM Zeiss LSM 5 Exciter has been used. Photos have been taken from area of 120 x 120 microns.Findings: The analysis of images and spectra has confirmed that the quality of thin films depends upon the used polymers. It was also observed that the parameters of the spin coating method have significant effect on the morphology and the optical properties. The spin rate has got a strong impact on them.Research limitations/implications: The morphology and optical properties of polyoxadiazoles thin films has been described. This paper include description how the spin rate influence on the polymer thin films. In order to use a polymer thin film in photovoltaics or optoelectronics it must have a high internal transmission density. Further research of polymer thin films are recommended.Practical implications: The spin coating method allows to deposit a uniform thin films. It is important to know how the spin rate influence on the thin films properties. It is also important to find a new use for this group of material engineering in photovoltaic or optoelectronics devices.Originality/value: The good properties of thin films make them suitable for various applications. The value of this paper is defining the optimal parameters of spin-coating technology for polyoxadiazoles thin films. The results allow the choosing optimal parameters of the deposition process. Spin coating is a very good method to obtain thin films which are obligated to have the same thickness over the whole surface.

  17. The electronic, optical and ferroelectric properties of BiFeO3 during polarization reversal: A first principle study

    International Nuclear Information System (INIS)

    Highlights: • The nonlinear optical response of BiFeO3 changes nonlinearly with polarization. • Nonlinear optical response could be used as criteria for the polarization reversal. • Analyzed the origin of the change of nonlinear optical response. • The hybridization of Bi 6s and O 2p leads to the ferroelectric displacement. - Abstract: Rhombohedral BiFeO3 which has a large spontaneous polarization is a candidate material for ferroelectric random access memory (FeRAM). And the polarization reversal is the key factor for the application of FeRAM. Here, the electronic, linear and nonlinear optical properties, structure and its stability of BiFeO3 during the continuous polarization reversal from reference cubic phase to ferroelectric R3c phase were systematically investigated by LSDA + U (local spin density approximation plus Hubbard U) and DFPT (density functional perturbation theory) method. We proposed that the nonlinear optical second order coefficients could be indicators to check the polarization reversal of BiFeO3 and our result showed that the coefficient reach its maximum between 20% distortion and 40% distortion during the half path of the reversal. The relationship between the nonlinear optical second order coefficient and the Bader charge was also compared and we found the coefficient is also dependent on the Bader charge. In addition, the linear optical absorption coefficient was calculated; the obvious change in absorption peaks was observed during the transition. By comparing the crystal orbital of the reference cubic phase and distorted R3c phase we found that the hybridized Bi 6s and O 2p is the main reason that causes the structure distortion. The local phonon density of states proves that the Bi and O interaction is the origin of the instability of cubic phase BiFeO3. The factor group analysis showed the change of Raman and IR modes during the transition

  18. Optical characteristics of the thin-film scintillator detector

    International Nuclear Information System (INIS)

    A study of the thin-film detector (TFD) was made in which various light guide and scintillator film support configurations were tested for efficiency of light coupling. Masking of selected portions of the photomultiplier (PM) tube face revealed the extent to which emitted light was received at the exposed PM surfaces. By blocking off selected areas of the scintillator film surface from direct view of the PM tube faces, a measure of the light-guiding efficiency of the film and its support could be estimated. The picture that emerges is that, as the light which is initially trapped in the thin film spreads radially outward from the ion entrance/exit point, it is scattered out of the film by minute imperfections. Optimum signals were obtained by a configuration in which the thin scintillator film was supported on a thin rectangular Celluloid frame inserted within a highly polished metal cylindrical sleeve

  19. Optical thin film metrology for optoelectronics

    International Nuclear Information System (INIS)

    The manufacturing of optoelectronic thin films is of key importance, because it underpins a significant number of industries. The aim of the European joint research project for optoelectronic thin film characterization (IND07) in the European Metrology Research Programme of EURAMET is to develop optical and X-ray metrologies for the assessment of quality as well as key parameters of relevant materials and layer systems. This work is intended to be a step towards the establishment of validated reference metrologies for the reliable characterization, and the development of calibrated reference samples with well-defined and controlled parameters. In a recent comprehensive study (including XPS, AES, GD-OES, GD-MS, SNMS, SIMS, Raman, SE, RBS, ERDA, GIXRD), Abou-Ras et al. (Microscopy and Microanalysis 17 [2011] 728) demonstrated that most characterization techniques have limitations and bottle-necks, and the agreement of the measurement results in terms of accurate, absolute values is not as perfect as one would expect. This paper focuses on optical characterization techniques, laying emphasis on hardware and model development, which determine the kind and number of parameters that can be measured, as well as their accuracy. Some examples will be discussed including optical techniques and materials for photovoltaics, biosensors and waveguides.

  20. Antimony selenide thin-film solar cells

    Science.gov (United States)

    Zeng, Kai; Xue, Ding-Jiang; Tang, Jiang

    2016-06-01

    Due to their promising applications in low-cost, flexible and high-efficiency photovoltaics, there has been a booming exploration of thin-film solar cells using new absorber materials such as Sb2Se3, SnS, FeS2, CuSbS2 and CuSbSe2. Among them, Sb2Se3-based solar cells are a viable prospect because of their suitable band gap, high absorption coefficient, excellent electronic properties, non-toxicity, low cost, earth-abundant constituents, and intrinsically benign grain boundaries, if suitably oriented. This review surveys the recent development of Sb2Se3-based solar cells with special emphasis on the material and optoelectronic properties of Sb2Se3, the solution-based and vacuum-based fabrication process and the recent progress of Sb2Se3-sensitized and Sb2Se3 thin-film solar cells. A brief overview further addresses some of the future challenges to achieve low-cost, environmentally-friendly and high-efficiency Sb2Se3 solar cells.