Oxygen vacancies in BaTi<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Scharfschwerdt, Raphaela; Mazur, Anton S.; Schirmer, O. F.; Hesse, H.; Mendricks, S.

doi:10.1103/physrevb.54.15284

Cited by 102 publications

(92 citation statements)

References 18 publications

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“…Others emphasized that this and similar values of the g-factor (g = 1.963-1.975) should be ascribed to the Ti 3+ -V O , that is Ti 3+ -F + centers, rather than exactly to Ti 3+ [21][22][23][24]. These observations of Ti 3+ and Ti 3+ -V O signals at room temperature and above strongly contradict the reports of a different group of authors, where manifestation of the Ti 3+ ion in EPR spectra was observed only at rather low temperatures (below 250 K [17], even mostly below 80 K [18][19][20]). None of the mentioned references refers to mechanically activated BaTiO 3 , but mostly to doped BaTiO 3 ceramics obtained using different reduction or oxidation treatments.…”

Section: Resultscontrasting

confidence: 68%

“…On the other hand, several authors reported that the EPR peak with g ≈ 1.97 may be caused by intrinsic Ti 3+ related defects in BaTiO 3 [16][17][18][19][20][21][22][23][24] . A few of them observed this peak just in reduced BaTiO 3 ceramic [20,25]. Some authors whose examinations included EPR spectra at room temperature and above, attributed a peak at g = 1.97 to the localized Ti 3+ states [16].…”

Section: Resultsmentioning

confidence: 96%

“…None of the mentioned references refers to mechanically activated BaTiO 3 , but mostly to doped BaTiO 3 ceramics obtained using different reduction or oxidation treatments. It is known that a major source of oxygen vacancies and F + centers or Ti 3+ -F + defects complexes in oxide perovskites refers to charge compensations of acceptor-type dopants and impurity cations, or to annealing treatments in reducing atmospheres [20,25]. Also, the excess of positive charge of donor-type dopants or similar impurities can be compensated by forming Ti 3+ centers or barium vacancies [17].…”

Section: Resultsmentioning

confidence: 99%

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Influence of mechanical activation on the structure of ultrafine BaTiO3 powders

Pavlović

Popović

Krstić³

et al. 2009

Journal of Alloys and Compounds

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Section: Resultscontrasting

confidence: 68%

Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

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Influence of mechanical activation on the structure of ultrafine BaTiO3 powders

Pavlović

Popović

Krstić³

et al. 2009

Journal of Alloys and Compounds

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“…These centers may appear from a trapped electron at a Ti 3+ e g ͑3d 3z 2 −r 2͒ orbital forming a paramagnetic complex. 16,17 Now that we have qualitatively described a plausible scenario for the larger Cu 2+ ESR linewidths in the oxygen deficient CaCu 3 Ti 4 O 12 samples, let us turn to the role played by the oxygen vacancies in the dielectric constants. In Fig.…”

Section: 17mentioning

confidence: 99%

“…11 Furthermore, paramagnetic complexes arising from Ti 3+ ions coupled to an oxygen vacancy were experimentally found to occur in ferroelectric materials such as BaTiO 3 . 13,16,17 Therefore the presence of oxygen vacancies in the CaCu 3 Note that the IBLC and vacancy effects are difficult to separate from each other and in some cases are related. The combination of these effects may account for the conflicting data and interpretations in literature.…”

Section: 17mentioning

confidence: 99%

Role of oxygen vacancies in the magnetic and dielectric properties of the high-dielectric-constant systemCaCu3Ti4O12: An electron-spin resonance study

et al. 2006

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We report experiments of electron spin resonance ͑ESR͒ of Cu 2+ in polycrystalline samples of CaCu 3 Ti 4 O 12 post-annealed in different atmospheres. After being synthesized by solid state reaction, pellets of CaCu 3 Ti 4 O 12 were annealed for 24 h at 1000°C under air, Ar or O 2 . Our temperature dependent ESR data revealed for all samples nearly temperature independent g value ͑2.15͑1͒͒ and linewidth for T ӷ T N Ϸ 25 K. However, the values of ESR linewidth are strongly affected by the oxygen content in the sample. For instance, argon post-annealed samples show a much larger linewidth than the O 2 or air post-annealed samples. We attribute this broadening to an increase of the dipolar homogeneous broadening of the Cu 2+ ESR lines due to the presence of oxygen vacancies which induce an S =1/2 spin inside the TiO 6 octahedra. Correlation between a systematic dependence of the ESR linewidth on the oxygen content and the high dielectric constant of these materials is addressed. Also, ESR, magnetic susceptibility, and specific heat data for a single crystal of CaCu 3 Ti 4 O 12 and for polycrystals of CdCu 3 Ti 4 O 12 are reported.

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High‐Performance Programmable Memory Devices Based on Co‐Doped BaTiO₃

et al. 2011

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Recently, resistive random access memory (RRAM) devices have attracted great attentions for a variety of advantages such as high-density, high-speed, low-power, and thus promising applications in next-generation nonvolatile memory technology. [1][2][3][4] The memory effect is realized through switching between high resistance state (HRS) and low resistance state (LRS), controlled by electric fi eld with either opposite polarity (bipolar) or different magnitude (unipolar). In understanding this resistive switching (RS) effect, quite a number of microscopic mechanisms have been proposed, while the formation/rupture of conductive fi laments in insulating matrix as one of the major switching mechanisms has been intensively studied. [3][4][5] It is demonstrated that the composition of the conductive fi laments and their formation/rupture are remarkably materials-dependent, thus the RRAM device performance is materials dependent too. For the favored device performance, complex transition metal oxides may be the most promising candidates. [ 3 ] The strong correlation of electrons in these oxides brings out rich competing phenomena between various electronic phases in a delicate balance, allowing a phase change and thus dramatic change of the electrical property, e.g. resistance, in response to a minute external perturbation, e.g., an applied electric fi eld. [ 6 ] Furthermore, the atomic and/or electronic reconstruction at grain boundaries or doping centers in these oxides enriches the electronic phases, providing an opportunity for advanced electronics. [ 7 , 8 ] By an extensive testing of various oxide materials in terms of the RRAM performance, we eventually choose ferroelectric BaTiO 3 for the present study. A low-doping at the Ti-site can introduce itinerant electrons, leading to the presence of inhomogeneous state, i.e., the coexistence of metallic and ferroelectric phases. [ 9 ] As an electric fi eld is applied on this inhomogeneous state, the local Joule heating induced by inhomogeneous current distribution may lead to the reconstruction of local atomic and/or electronic phases, causing the large change in conductance. [ 8 , 10 ] Besides, earlier works suggested that the ferroelectric displacements will also change the electronic structure. [ 11 ] Hence, BaTiO 3 -based materials offer a good opportunity to develop the RRAM devices with more promising functionalities. In this work, we fabricate 5at% Co-doped BaTiO 3 (BTCO) fi lms. The unipolar RS characteristics with the endurance of more than 10 5 and switching time of less than 10 ns in addition to other preferred properties are demonstrated.We fabricated the BTCO-based memory cell, with the entire materials stack (thicknesses) of Au(400 nm)/BTCO(400 nm)/ Pt(300 nm)/Ti(50 nm)/SiO 2 (500 nm)/Si. The X-ray diffraction (XRD) data indicate that the BTCO fi lms are polycrystalline, as shown in Figure 1 a. Figure 1 b and c depict a schematic drawing of the measurement confi guration and the scanning electron Figure 1 . (a) XRD data of the as-prepared BaTi 0.95 Co ...

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Oxygen vacancies in BaTiO3

Cited by 102 publications

References 18 publications

Influence of mechanical activation on the structure of ultrafine BaTiO3 powders

Influence of mechanical activation on the structure of ultrafine BaTiO3 powders

Role of oxygen vacancies in the magnetic and dielectric properties of the high-dielectric-constant systemCaCu3Ti4O12: An electron-spin resonance study

High‐Performance Programmable Memory Devices Based on Co‐Doped BaTiO₃

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Oxygen vacancies in BaTiO3

Cited by 102 publications

References 18 publications

Influence of mechanical activation on the structure of ultrafine BaTiO3 powders

Influence of mechanical activation on the structure of ultrafine BaTiO3 powders

Role of oxygen vacancies in the magnetic and dielectric properties of the high-dielectric-constant systemCaCu3Ti4O12: An electron-spin resonance study

High‐Performance Programmable Memory Devices Based on Co‐Doped BaTiO3

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High‐Performance Programmable Memory Devices Based on Co‐Doped BaTiO₃