Physik der Ferrite und der verwandten magnetischen Oxide

Krupička, S.

doi:10.1007/978-3-322-83522-2

Cited by 257 publications

(97 citation statements)

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“…(1) and (2) points to the wide range of relaxation times. 10,11 These equations are used for studying of ferroelectric ceramics as well as ferrites.…”

Section: Resultsmentioning

confidence: 99%

F-center mechanism of long-term relaxation in lead zirconate-titanate-based piezoelectric ceramics. 1. After-heating relaxation

Ishchuk¹,

Kuzenko²

2015

J. Adv. Dielect.

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Results of experimental investigation of relaxation aging processes in Pb(Zr,Ti)O 3 -based solid solutions after termination of external actions are presented. Heating, DC electric field, uniaxial pressure and some of their combinations were taken as external actions. In the main part of the present paper, we use heating as external action. The said processes are long-time one and are described by the logarithmic function of time.Reversible and nonreversible relaxation processes take place depending on the action intensity. The relaxation rate depends on the action intensity also, and the said dependence has nonlinear and nonmonotonic form if external action leads to domain disordering.The oxygen vacancies-based model for description of the long-time relaxation processes is suggested. The model takes into account oxygen vacancies on the sample's surface ends, their conversion into F þ -and F 0 -centers under external effects (due to the liberation of the pyroelectric charge) and subsequent relaxation of these centers into the simple oxygen vacancies after the actions termination. The initial sample's state is electroneutrality one. F-center formation leads to the violation of the original sample's electroneutrality, and generates DC electric field into the sample. Relaxation of F-centers is accompanied by decreasing of electric field, induced by them, and dielectric constant relaxation as consequent effect.

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“…(1) and (2) points to the wide range of relaxation times. 10,11 These equations are used for studying of ferroelectric ceramics as well as ferrites.…”

Section: Resultsmentioning

confidence: 99%

F-center mechanism of long-term relaxation in lead zirconate-titanate-based piezoelectric ceramics. 1. After-heating relaxation

Ishchuk¹,

Kuzenko²

2015

J. Adv. Dielect.

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“…A handbook by Dunlop and Ö zdemir [1997] is written mainly for rock magnetists and provides very good insight into the physical principles of magnetism. Among the classical literature, let us refer to the Nobel lecture of Néel [1970], and older, very good handbooks of Krupička [1969Krupička [ , 1973, focusing on magnetism of ferrites and iron oxides.…”

Section: Short Excursion Into Theorymentioning

confidence: 99%

“…For the following, we used the approach described in the handbooks of Krupička [1969Krupička [ , 1973.…”

Section: Ferrimagnetism and Antiferromagnetismmentioning

confidence: 99%

On determination of the Curie point from thermomagnetic curves

2006

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[1] In many rock magnetic studies, information on magnetic mineralogy is of crucial importance. Besides standard analytical methods, such as X-ray spectroscopy, more sensitive thermomagnetic analyses are often used. Temperature dependence of magnetic parameters can serve as basis for determination of magnetic second-order phase transition temperatures. Although limited by several drawbacks, the most serious being thermally induced transformations of the original minerals, this method provides useful information not only about the presence of magnetic minerals, but also additional knowledge on, e.g., the prevailing grain size distribution or degree of substitution. In thermomagnetic analysis, temperature dependence of two parameters, induced magnetization and magnetic susceptibility, is mostly used. However, let us say because of historical reasons, the same approach for the Curie point determination has been often used in analyzing the two parameters. In our contribution, we discuss the physical principles of the two parameters, showing that the methods developed and used for induced magnetization cannot be used also for temperature dependence of magnetic susceptibility because there is no physical justification to do so. Otherwise, the error in determining the Curie point can be some few degrees but can reach also several tens of degrees. Such an error has serious consequences for further interpretation of the data, e.g., in terms of degree of Ti substitution in Ti magnetite.

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“…The results show that zinc favours the tetrahedral coordinated spin-down sites 4f 1 in these synthetic hexagonal ferrites as well as in natural magnetoplumbite samples and in spinel-type ferrites [25]. Reasons for such a behaviour are the preference energy of the Zn 2+ -ion and its tendency to form covalent bonds [26]. The fact that the trigonal-bipyramidal site 2b is formed from two face-bonded tetraeders explains the occurence of zinc (with a small yield) also in this sites.…”

Section: Resultsmentioning

confidence: 97%

Synthesis and characterization of hexagonal ferrites BaFe_12‐2xZn_xTi_xO₁₉ (0 ≤ x ≤ 2) by thermal decomposition of freeze‐dried precursors

Rösler¹,

Wartewig²,

Langbein³

2003

Cryst. Res. Technol.

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Substituted barium hexaferrites, BaFe 12-2x Zn x Ti x O 19 (0 ≤ x ≤ 2), have been synthesized by thermal decomposition of freeze-dried acetate precursors. Decomposition and phase formation were investigated by means of thermal analysis, XRD and IR spectroscopy. The initially amorphous decomposed precursor reacts to the substituted hexaferrite via a spinel-like maghemite (γ-Fe 2 O 3 ) and Zn/Ti containing spinel ferrites. The synthesis method allows a decrease of the reaction temperature and time, necessary for producing a single phase hexaferrite. At relative low reaction temperatures, the substitution rate x shows remarkable differences at different iron sublattices. For x ≤ 0,8 this selective substitution results in an increase of magnetization as x grows.

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Physik der Ferrite und der verwandten magnetischen Oxide

Cited by 257 publications

References 0 publications

F-center mechanism of long-term relaxation in lead zirconate-titanate-based piezoelectric ceramics. 1. After-heating relaxation

F-center mechanism of long-term relaxation in lead zirconate-titanate-based piezoelectric ceramics. 1. After-heating relaxation

On determination of the Curie point from thermomagnetic curves

Synthesis and characterization of hexagonal ferrites BaFe_12‐2xZn_xTi_xO₁₉ (0 ≤ x ≤ 2) by thermal decomposition of freeze‐dried precursors

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Physik der Ferrite und der verwandten magnetischen Oxide

Cited by 257 publications

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F-center mechanism of long-term relaxation in lead zirconate-titanate-based piezoelectric ceramics. 1. After-heating relaxation

F-center mechanism of long-term relaxation in lead zirconate-titanate-based piezoelectric ceramics. 1. After-heating relaxation

On determination of the Curie point from thermomagnetic curves

Synthesis and characterization of hexagonal ferrites BaFe12‐2xZnxTixO19 (0 ≤ x ≤ 2) by thermal decomposition of freeze‐dried precursors

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Synthesis and characterization of hexagonal ferrites BaFe_12‐2xZn_xTi_xO₁₉ (0 ≤ x ≤ 2) by thermal decomposition of freeze‐dried precursors