Magnetic properties of nanocrystalline KNbO3

Головина, И. С.; Shanina, B. D.; Kolesnik, S. P.; Geǐfman, I. N.; Andriiko, A. A.

doi:10.1063/1.4829702

Cited by 22 publications

(21 citation statements)

References 16 publications

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“…Classical examples are unexpected experimental results of Yadlovker and Berger [16,17,18], which reveal the enhancement of polar properties of cylindrical nanoparticles of Rochelle salt. Frey and Payne [19], Zhao et al [20], Drobnich et al [21], Erdem et al [22] and Golovina et al [23,24,25] demonstrate the possibility to control the phase transitions (including new polar phases appearance) for BaTiO3, S2P2S6, PbTiO3 and KTa1-хNbхO3 nanopowders and nanoceramics by finite size effects.…”

Section: Introductionmentioning

confidence: 99%

Labyrinthine domains in ferroelectric nanoparticles: Manifestation of a gradient-induced morphological transition

et al. 2018

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In the framework of the Landau-Ginzburg-Devonshire (LGD) approach we studied finite size effects of the phase diagram and domain structure evolution in spherical nanoparticles of uniaxial ferroelectric. The particle surface is covered by a layer of screening charge characterized by finite screening length. The phase diagram, calculated in coordinates "particle radius -screening length" has a wide region of versatile poly-domain structures separating single-domain ferroelectric and nonpolar paraelectric phases. Unexpectedly, we revealed a region of stable irregular labyrinthine domains in the nanoparticles of uniaxial ferroelectric CuInP2S6 with the first order paraelectric-ferroelectric phase transition. We established that the origin of labyrinthine domains is the mutual balance of LGD, polarization gradient and electrostatic energies. The branching of the domain walls appears and increases rapidly when the polarization gradient energy decreases below the critical value.Allowing for the generality of LGD approach, we expect that the gradient-induced morphological transition can be the source of labyrinthine domains appearance in many spatially-confined ferroics with long-range order parameter, including relaxors, ferromagnetics, antiferrodistortive materials and materials with incommensurate ferroic phases.

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Section: Introductionmentioning

confidence: 99%

Labyrinthine domains in ferroelectric nanoparticles: Manifestation of a gradient-induced morphological transition

et al. 2018

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“…Frey and Payne [108], Zhao et al [109], and Erdem et al [110] demonstrated a possibility to control the temperature of a ferroelectric phase transition, as well as the magnitude and position of a dielectric permittivity maximum, for BaTiO 3 and PbTiO 3 nanopowders and nanoceramics. The research of KTa 1− Nb O 3 nanopowders [111] and ceramic nanograins [112][113][114] revealed the emergence of new polar phases and a shift of the phase transition temperature with respect to that in bulk crystals. The size effects were detected in SrBi 2 Ta 2 O 9 nanoparticles by Yu et al [115] and Ke et al [116], by using Raman spectroscopy.…”

Section: Multiferroic Nanoparticles the State Of Artmentioning

confidence: 99%

Renovation of Interest in the Magnetoelectric Effect in Nanoferroics

Glinchuk

Khist

2018

Ukr. J. Phys.

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Recent theoretical studies of the influence of the magnetoelectric effect on the physical properties of nanosized ferroics and multiferroics have been reviewed. Special attention is focused on the description of piezomagnetic, piezoelectric, and linear magnetoelectric effects near the ferroid surface in the framework of the Landau–Ginzburg–Devonshire phenomenological theory, where they are considered to be a result of the spontaneous surface-induced symmetry reduction. Therefore, nanosized particles and thin films can manifest pronounced piezomagnetic, piezoelectric, and magnetoelectric properties, which are absent for the corresponding bulk materials. In particular, the giant magnetoelectric effect induced in nanowires by the surface tension is possible. A considerable influence of size effects and external fields on the magnetoelectric coupling coefficients and the dielectric, magnetic, and magnetoelectric susceptibilities in nanoferroics is analyzed. Particular attention is paid to the influence of a misfit deformation on the magnetoelectric coupling in thin ferroic films and their phase diagrams, including the appearance of new phases absent in the bulk material. In the framework of the Landau–Ginzburg–Devonshire theory, the linear magnetoelectric and flexomagnetoelectric effects induced in nanoferroics by the flexomagnetic coupling are considered, and a significant influence of the flexomagnetic effect on the nanoferroic susceptibility is marked. The manifestations of size effects in the polarization and magnetoelectric properties of semiellipsoidal bismuth ferrite nanoparticles are discussed.

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“…It was established experimentally that extrinsic and intrinsic defects play a crucial role in the impurities [9,13,49]. It is known that the concentration of defects inside the crystal is inhomogeneous and strongly increases when going from the bulk to the surface of the particle [49].…”

Section: Ii1 Model Background For Ktao 3 -Knbo 3 Systemmentioning

confidence: 99%

Effect of Vegard strains on the extrinsic size effects in ferroelectric nanoparticles

et al. 2014

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By changing the size and the shape of ferroelectric nanoparticles, one can govern their polar properties including their improvements in comparison with the bulk prototypes. At that the shift of the ferroelectric transition temperature can reach as much as hundreds of Kelvins. Phenomenological description of these effects was proposed in the framework of Landau-Ginsburg-Devonshire (LGD) theory using the conceptions of surface tension and surface bond contraction. However, this description contains a series of poorly defined parameters, which physical nature is ambiguous. It is appeared that the size and shape dependences of the phase transition temperature along with all polar properties are defined by the nature of the size effect.Existing LGD-type models do not take into account that defects concentration strongly increases near the particle surface. In order to develop an adequate phenomenological description of size effects in ferroelectric nanoparticles, one should consider Vegard strains (local lattice deformations) originated from defects accumulation the near surface.In the paper we propose a theoretical model that takes into account Vegard strains and perform a detailed quantitative comparison of the theoretical results with experimental ones for quasi-spherical nanoparticles, which reveal the essential (about 100 K) increase of the transition temperature in spherical nanoparticles in comparison with bulk crystals. The average radius of nanoparticles was about 25 nm, they consist of KTa 1х Nb х O 3 solid solution, where KTaO 3 is a quantum paraelectric, while KNbO 3 is a ferroelectric. From the comparison between the theory and experiment we unambiguously established the leading contribution of Vegard strains into the extrinsic size effect in ferroelectric nanoparticles. We determined the dependence of * Corresponding author 1: anna.n.morozovska@gmail.com † Corresponding author 2: isgolovina@ukr.net 1 Vegard strains on the content of Nb and reconstructed the Curie temperature dependence on the content of Nb using this dependence. Appeared that the dependence of the Curie temperature on the Nb content becomes non-monotonic one for the small (< 20 nm) elongated KTa 1-х Nb х O 3 nanoparticles. We established that the accumulation of intrinsic and extrinsic defects near the surface can play the key role in the physical origin of extrinsic size effect in ferroelecric nanoparticles and govern its main features.

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Magnetic properties of nanocrystalline KNbO3

Cited by 22 publications

References 16 publications

Labyrinthine domains in ferroelectric nanoparticles: Manifestation of a gradient-induced morphological transition

Labyrinthine domains in ferroelectric nanoparticles: Manifestation of a gradient-induced morphological transition

Renovation of Interest in the Magnetoelectric Effect in Nanoferroics

Effect of Vegard strains on the extrinsic size effects in ferroelectric nanoparticles

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