Peculiarities of the radiospectroscopy line shape in nanomaterials

Glinchuk, M. D.; Morozovskaya, A. N.; Slipenyuk, A. M.; Bykov, I. P.

doi:10.1007/bf03166934

Cited by 13 publications

(12 citation statements)

References 16 publications

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“…are the coefficients obtained in [10] from the condition of normalization, ω 0pc and ω 0ps are resonance frequency, respectively, for core and shell regions. Here resonance frequency in the ferroelectric phase ω 0f can be proportional to linear or squared polarization in ESR case and to the fourth power of polarization in NMR case because for the transition +1/2 ↔ −1/2 the resonance frequency is proportional to square quadrupole coupling constant, namely ω 0q ∼ (eQ) 2 P 4 (r, R), where eQ denotes the quadrupole moment of nuclei.…”

Section: Spectra Of Magnetic Resonancesmentioning

confidence: 99%

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Size Effects in Radiospectroscopy Spectra of Ferroelectric Nanopowders

et al. 2005

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The theoretical and experimental investigation of ferroelectric nanopowders is performed. The manifestation in radiospectroscopy spectra of size driven ferroelectric-paraelectric phase transition at some critical particle average size R = R c was the main goal of the consideration. In theoretical part the size effect for the materials with ferroelectric tetragonal phase at room temperature and cubic paraelectric phase was considered allowing for the spontaneous polarization inhomogeneity inside a particle and distribution of particle sizes. In ESR the transformation of the spectra from tetragonal symmetry to cubic symmetry lines with decrease in nanoparticle sizes was calculated. The method of Rc value extraction from the ratio of the different symmetry lines intensities in the absorption spectra was proposed. Measurements of Fe 3+ ESR spectra in nanopowder of BaTiO3 were carried out at room temperature. The samples were prepared by rate-controlled method with different particle sizes, which depend on annealing temperature. The decrease in intensity of tetragonal symmetry ESR lines of Fe 3+ and appearance of cubic symmetry line with asymmetry of the shoulders was observed with the average sizes decrease with complete disappearance of tetragonal spectrum at R ≤ 40 nm. The comparison of the theory with experiment was carried out. The theory fits experimental data pretty good. The value of critical size R c ≈ 40 nm was extracted from ESR data. The asymmetry and broadening of right hand side shoulder of ESR cubic symmetry line was shown to be related to contribution of paramagnetic centers in the vicinity of the particles surface with lower than cubic symmetry. The deconvolution of the cubic line allowed to show that this region size is about 3 nm.

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Section: Spectra Of Magnetic Resonancesmentioning

confidence: 99%

“…[9][10][11]). The main advantage of these methods is their ability to study local properties of the solids that is very important for nanomaterials, namely nanograin ceramics, nanoparticle powders, thin films.…”

Section: Introductionmentioning

confidence: 99%

Size Effects in Radiospectroscopy Spectra of Ferroelectric Nanopowders

et al. 2005

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“…[19][20][21][22] Within this context, the approach applied for ceramics and nanopowders is reasonably extending to thin films. Just like in the case of BT-based films in this study, the BT thin films in Ref.…”

Section: Resultsmentioning

confidence: 99%

Low temperature dielectric relaxation and charged defects in ferroelectric thin films

et al. 2013

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We report a dielectric relaxation in BaTiO3-based ferroelectric thin films of different composition and with several growth modes: sputtering (with and without magnetron) and sol-gel. The relaxation was observed at cryogenic temperatures (T < 100 K) for frequencies from 100 Hz up to 10 MHz. This relaxation activation energy is always lower than 200 meV and is very similar to the relaxation that we reported in the parent bulk perovskites. Based on our Electron Paramagnetic Resonance (EPR) investigation, we ascribe this dielectric relaxation to the hopping of electrons among Ti3+-V(O) charged defects. Being dependent on the growth process and on the amount of oxygen vacancies, this relaxation can be a useful probe of defects in actual integrated capacitors with no need for specific shaping

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“…However it was shown by consideration of ferroelectric nanoparticles with taking into account surface tension contribution [15] that the changing of properties is especially strong in some region in vicinity of surface (shell region) while they are close to those in bulk in the central part of a particle (core region). The model of "shell", which "feels" the influence of surface and "core" with the properties like those in the bulk was proposed recently for description of radiospectroscopy spectra in the oxides [16]. Since the ratio of the shell to the core contribution increases with the particles sizes decrease the proposed model allowed to explain successfully the observed transformation of NMR spectra of 17 O in MgO nanopowder from one line characteristic to bulk sample into two lines originated from core and shell with the sizes decrease.…”

Section: Ionic Conductivity In Nanoparticlesmentioning

confidence: 99%

Mechanism of the decrease of barriers for oxygen ionic conductivity in nanocrystalline ceramics

Glinchuk

Bykov

Hilczer

2007

Physica Status Solidi (b)

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We calculated the influence of surface tension on the barriers of oxygen ionic conductivity in nanograin ceramics. Activation energy of oxygen ions diffusion via oxygen vacancies which were considered as the dilatational centers was calculated. This energy was shown to decrease with nanoparticle sizes decreasing. The distribution function of activation energy was derived on the basis of distribution of nanoparticle sizes. We obtained an analytical expressions of ionic conductivity dependence on the temperature and nanograin sizes. These formulas fitted pretty good the observed earlier behaviour of oxygen conductivity in nanograin ceramics of ZrO 2 :16% Y observed earlier. Therefore the consideration we carried out had shown that the surface tension in nanoparticles is physical mechanism responsible for the essential enhancement of the oxygen ionic conductivity observed in nanograin samples, the main contribution to the conductivity being related to the region in vicinity of the particle surface.

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Peculiarities of the radiospectroscopy line shape in nanomaterials

Cited by 13 publications

References 16 publications

Size Effects in Radiospectroscopy Spectra of Ferroelectric Nanopowders

Size Effects in Radiospectroscopy Spectra of Ferroelectric Nanopowders

Low temperature dielectric relaxation and charged defects in ferroelectric thin films

Mechanism of the decrease of barriers for oxygen ionic conductivity in nanocrystalline ceramics

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