EPR of the Gd3+probe near ferroelectric phase transition in Pb5Ge3O11

Trubitsyn, M. P.; Waplak, S.; Krokhmal, Yu. D.

doi:10.1080/01411590601090930

Cited by 4 publications

(8 citation statements)

References 2 publications

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“…In order to reveal the mechanisms of the anomalous broadening of EPR signals in the vicinity of ferroelectric phase transition, the orientational dependence of their linewidths was studied in detail. It must be pointed out that the obtained results do not correlate well with the conclusions presented in [1,2].…”

Section: Introductioncontrasting

confidence: 69%

“…We assume, as the authors in [1,2], that it is possible to restrict ourselves to the first terms in the expansion (5). The results of such approximation are presented in Figure 4.…”

Section: Epr and Temperature Behaviour Of The Order Parametermentioning

confidence: 98%

“…Such type of investigations employs a weak dependence of the characteristic behaviour of structural phase transitions on the presence of impurity defects in a crystal in an amount necessary for the detection of paramagnetic resonance. [3À7] In our paper, the temperature dependence of spontaneous polarization was obtained from the temperature dependences of the EPR signal positions measured in a wider temperature range as compared with [1,2]. This enabled us to determine the parameters of the LandauÀDevonshire thermodynamic potential with a higher accuracy.…”

Section: Introductionmentioning

confidence: 99%

“…The authors of [1,2] have studied the temperature dependence of resonance positions and widths of electron paramagnetic resonance (EPR) lines in the vicinity of ferroelectric phase transition in lead germanate (Pb 5 Ge 3 O 11 ), using as a probe Gd 3C ions. The data obtained have been used by the authors both for the construction of the temperature dependence of the order parameter and for the estimation of a critical interval in which thermodynamic anomalies traceable to local fluctuations of the order parameter are essential.…”

Section: Introductionmentioning

confidence: 99%

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Study of ferroelectric phase transition in Pb₅Ge₃O₁₁by paramagnetic resonance of Gd³⁺centres

et al. 2015

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To cite this article: V.A. Vazhenin, E.L. Rumyantsev, M.Yu. Artyomov & A.P. Potapov (2015): Study of ferroelectric phase transition in Pb 5 Ge 3 O 11 by paramagnetic resonance of Gd 3+ centres, Phase Transitions,The temperature dependence of the fine structure of trigonal paramagnetic Gd 3C centres in Pb 5 Ge 3 O 11 was investigated in a wide temperature range in the vicinity of structural phase transition. The temperature dependence of the squared order parameter has been constructed based on the obtained data. It was shown that for the adequate description of its behaviour, the sixth-power term in polarization must be taken into account in the expansion of the thermodynamic potential. The orientational dependence of anomalous broadening of electron paramagnetic resonance signals in the vicinity of ferroelectric phase transition was studied. By comparison of the observed behaviour with the angular dependences of the line width that are characteristic of various broadening mechanisms, it was inferred that it can be attributed to defect induced statistical dispersion of fine structure triclinic parameters.

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Section: Introductioncontrasting

confidence: 69%

“…We assume, as the authors in [1,2], that it is possible to restrict ourselves to the first terms in the expansion (5). The results of such approximation are presented in Figure 4.…”

Section: Epr and Temperature Behaviour Of The Order Parametermentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Study of ferroelectric phase transition in Pb₅Ge₃O₁₁by paramagnetic resonance of Gd³⁺centres

et al. 2015

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“…(2) and to the deviation of the behavior of the order parameter in lead germanate [17,18] from the dependence (3) (T 0 is the temperature of the structural transition) typ ical for second order phase transitions. For the cen ters, which do not have the symmetry plane σ h ⊥ C 3 in the paraelectric phase, the contribution Δb 20 (P) includes both odd and even powers of P; consequently, these complexes should exhibit dissimilar behavior of B res (T).…”

Section: +mentioning

confidence: 99%

dimer paramagnetic centers in lead germanate crystals doped with iron and halogen (Cl−, Br−, F−) ions

et al. 2013

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Electron paramagnetic resonance (EPR) of trig onal Fe3+ centers (the ground state 6 S 5/2 ) in ferroelec tric lead germanate was studied in [1][2][3]. As a result, it was concluded that these centers are associated with individual trivalent iron ions localized in the position Pb7 (in the notation of [4]) of the ferroelectric phase Pb 5 Ge 3 O 11 . The local symmetry of the center increases in the paraelectric phase: C 3 C 3h . It was found in [5] that annealing of the above crystals in chlorine containing atmosphere leads to the appear ance of several Fe 3+ -Cl -dimer complexes with tri clinic symmetry, so that the chlorine ions are situated in the interstices of the channel (Fig. 1) formed by the Pb triangles and running along the C 3 axis [4,6]. This work is devoted to studying the mechanisms of the for mation of defects under doping of lead germanate by various halogen ions. 2.The measurements were performed on poly and single domain samples of Pb 5 Ge 3 O 11 single crystals grown with the use of the Czochralski method from the charge produced by solid phase synthesis and doped with 0.01-0.2 mol % Fe. The second order fer roelectric transition P3( ) ( ) in pure lead germanate occurs at a temperature of 450 K [7]; its crystalline structure at room temperature and at 473 K was found in [4,6] by neutron diffraction. To dope the crystals by halogen ions the samples were annealed at 800 K in the corresponding atmosphere for two hours. To prepare the chlorine , bromine , and fluorine con taining atmospheres in an open bulb we used ZnCl 2 , CsBr, and polytetrafluoroethylene (teflon), respec tively. The samples were made single domain by cool ing them down from 450 K in an electric field of 150 V/mm. The measurements were carried out on aBruker EMX Plus X band EPR spectrometer in the temperature range of 100-500 K.3. The EPR spectra in the region of the high field transition 5 6 (or 1/2 3/2, see Fig. 1 in [5]) of the Fe 3+ trigonal center in the initial and annealed Pb 5 Ge 3 O 11 samples at room temperature in the mag netic field B || C 3 are shown in Fig. 2. Annealing in the presence of zinc chloride (spectrum b in Fig. 2) leads to a considerable increase in the intensity of three sat ellites (marked by vertical arrows). In [5], these satel lites were attributed to the transitions of Fe 3+ -Cldimer complexes. It should be mentioned that the number of nonequivalent Fe 3+ -Cl -centers is actually more than 3, as indicated, e.g., by an increase in the line width of the trigonal complex, but we did not manage to resolve all of them. The presence of these centers in the initial crystal is caused by a small chlo ride contamination of germanium dioxide used in the charge synthesis.The temperature behavior of the positions of the signals in spectrum b (Fig. 2) is shown in Fig. 3. It proved impossible to measure the temperature depen dence for two satellites in the entire range owing to their overlap and strong (almost an order of magni tude) broadening at high temperatures. The bend in the temperature dependences near 435 ...

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Paramagnetic copper centers in ferroelectric lead germanate with halogens

et al. 2014

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EPR of the Gd³⁺probe near ferroelectric phase transition in Pb₅Ge₃O₁₁

Cited by 4 publications

References 2 publications

Study of ferroelectric phase transition in Pb₅Ge₃O₁₁by paramagnetic resonance of Gd³⁺centres

Study of ferroelectric phase transition in Pb₅Ge₃O₁₁by paramagnetic resonance of Gd³⁺centres

dimer paramagnetic centers in lead germanate crystals doped with iron and halogen (Cl−, Br−, F−) ions

Paramagnetic copper centers in ferroelectric lead germanate with halogens

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EPR of the Gd3+probe near ferroelectric phase transition in Pb5Ge3O11

Cited by 4 publications

References 2 publications

Study of ferroelectric phase transition in Pb5Ge3O11by paramagnetic resonance of Gd3+centres

Study of ferroelectric phase transition in Pb5Ge3O11by paramagnetic resonance of Gd3+centres

dimer paramagnetic centers in lead germanate crystals doped with iron and halogen (Cl−, Br−, F−) ions

Paramagnetic copper centers in ferroelectric lead germanate with halogens

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Product

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EPR of the Gd³⁺probe near ferroelectric phase transition in Pb₅Ge₃O₁₁

Study of ferroelectric phase transition in Pb₅Ge₃O₁₁by paramagnetic resonance of Gd³⁺centres

Study of ferroelectric phase transition in Pb₅Ge₃O₁₁by paramagnetic resonance of Gd³⁺centres