Low-temperature phase transformations in weakly doped quantum paraelectrics: novel features and quantum reentrant dipolar glass state in KTa0.982Nb0.018O3

Трепаков, В. А.; Prosandeev, S. A.; Savinov, M.; Galinetto, P.; Samoggia, G.; Kapphan, S.; Jastrabı́k, L.; Boatner, L. A.

doi:10.1016/j.jpcs.2004.02.012

Cited by 9 publications

(12 citation statements)

References 59 publications

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“…a small admixture of the first order PT, and is caused by the change from the positive to negative of the β coefficient of P 4 in the Landau free energy function in the vicinity of the PT. This agrees well with a small temperature hysteresis in the PT region of KTN-1.8 observed in [13,14]. Below 27 K, the dc electric field permittivity dependence has a complex character due to the appearance of the dielectric hysteresis, mixed phase formation with competition of the polar long-range and short-range ordering and, finally, dipole-glass-like state arising at lower temperatures (analogies for ferromagnets see e.g.…”

Section: Resultssupporting

confidence: 85%

“…As result, above 27 K the linear permittivity agrees well with dominating behaviour characteristic of conventional displacive-type ferroelectrics with low-T phase transitions. At the same time, rounding of the ε(T) maximum and occurrence of a small temperature region in the immediate proximity to PT point in which ε(T) behaviour obeys the Curie-Weiss law with T Cg ~ 17 K (which is very close to the glass transition temperature T g ~ 15 K [13,14]) clearly evidence low-T dipole glass formation trends. Figure 2 presents the dc field dependence of the dielectric permittivity at different temperatures.…”

Section: Resultsmentioning

confidence: 73%

“…The KTN-1.8 single crystals growth, {100} oriented specimens preparation and linear permittivity measurements technique have been described in [13,14]. The dielectric response versus a bias dc fields was measured at the level of 0-1.4 kV/cm.…”

Section: Methodsmentioning

confidence: 99%

“…Just recently we reported on permittivity and Raman scattering studies for Nb impurity induced phase transition in diluted KTN with x = 0.0018, KTN-1.8 [14,13]. The practically nondisprsive (100 Hz -1 MHz) dielectric permittivity goes over a sharp maximum at the transition point T C ~ 27 K accompanied by intensity increasing, splitting and stiffness of the TO1 ferroelectric (FE) soft mode at further cooling.…”

Section: Introductionmentioning

confidence: 97%

“…We report on new analyses of the linear permittivity are supplemented by nonlinear dielectric permittivity measurements on external dc field for the KTN-1.8 specimens used in [13,14]. Nonlinear dielectric permittivity is much more sensitive to dipole or glass order and mixed phases formation [15].…”

Section: Introductionmentioning

confidence: 99%

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Low temperature structural transformations of dilute KTa _1–x Nb _x O ₃ : x = 0.018, quantum superparaelectric or reentrant glass scenario?

Трепаков

Savinov

Prosandeev

et al. 2005

phys. stat. sol. (c)

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Impurity induced structural transformations are studied for KTa 1-x Nb x O 3 with x = 0.0018 (KTN-1.8) by low-frequency linear and non-linear dielectric spectroscopy techniques. Nb admixture leads to the appearance of a sharp ε′(T) maximum accompanying the ferroelectric phase transition at T C ~ 27 K, and a glasslike state formation at lower temperatures. The linear permittivity evidences properties inherent to systems being near the quantum-mechanical displacive limit and shows the long range polar order with macroscopic polarization formation at ~ 27 K. This conclusion was proven by nonlinear polarization response stuidy under dc electric field action, which evidenced also the proximity of the three-critical point. Above 27 K, the nonlinearity increases at cooling in accordance with the Devonshire theory for the paraelectric phase of conventional ferroelectrics. Below 27 K, the random distribution of Nb 5+ ions and related system's inhomogeneities provoke a new low temperature phase state formation, which can be treated as reentrant polar-glass.

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Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 73%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Low temperature structural transformations of dilute KTa _1–x Nb _x O ₃ : x = 0.018, quantum superparaelectric or reentrant glass scenario?

Трепаков

Savinov

Prosandeev

et al. 2005

phys. stat. sol. (c)

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Cathodoluminescence from mixed KTaO₃‐KNbO₃ crystals

Kibar

Townsend

Wang

et al. 2007

Phys. Status Solidi (c)

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Cathodoluminescence spectra are shown for a sequence of mixed crystals of KTaO 3 :KNbO 3 . The luminescence emission bands are broadly similar across the spectrum from 250 to 850 nm, although their relative strengths are sensitive to composition and temperature. A UV band near 330 nm is only well resolved in some compositions and a broad line near 700 nm may arise from Cr ions. The presence of low temperature phase transitions within the crystals is evidenced by intensity steps and spectral changes of the cathodoluminescence. Hysteresis is seen, as are domain effects and electric field shifts of the transition temperatures. The cathodoluminescence of the surface material reveals more transitions than are reported from earlier bulk studies. ] pre-phase softening, precursor effects, plus additional phases [4,7] and existence of dipolar glassy states [8]. In part some differences may result from inaccuracies in the measurement of the Nb concentration, since there are significant differences between compositions of the growth melt and the crystal, as well as sample uniformity.The KTN materials offer a useful framework to explore phase transitions by variations in optical properties. Optical absorption and second harmonic generation have also revealed extra sub-phases [7]. Luminescence properties similarly reveal phase transitions, as briefly reviewed [9], with changes in spectra between phases (as for NH 4 Br [10]), minor wavelength shifts [11], charge release and intense emission events at the phase transition for KNbO 3 [12], irreversible phase changes [13], or those which require a high temperature regeneration of the starting phase [14] and hysteresis effects between cooling and heating [12]. There can be differences between the spectra and the number of detectable phase transitions when recording luminescence with X-ray excitation (RL, radioluminescence) or electrons (CL, cathodoluminescence) [15]. Such differences exist since surface relaxation processes sensed by CL can proceed more readily than those in the bulk material, as for RL. Surface damage as the result of polishing and/or contaminants may additionally result in local changes in phase, composition or dislocation density. Unexpected events can occur with dramatic intensity steps during heating or cooling at temperatures

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A combined X-ray diffraction and Raman scattering study of the phase transitions in Sr1−xCaxTiO3 (x=0.04, 0.06, and 0.12)

Mishra

Ranjan

Pandey

et al. 2005

Journal of Solid State Chemistry

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Low-temperature phase transformations in weakly doped quantum paraelectrics: novel features and quantum reentrant dipolar glass state in KTa0.982Nb0.018O3

Cited by 9 publications

References 59 publications

Low temperature structural transformations of dilute KTa _1–x Nb _x O ₃ : x = 0.018, quantum superparaelectric or reentrant glass scenario?

Low temperature structural transformations of dilute KTa _1–x Nb _x O ₃ : x = 0.018, quantum superparaelectric or reentrant glass scenario?

Cathodoluminescence from mixed KTaO₃‐KNbO₃ crystals

A combined X-ray diffraction and Raman scattering study of the phase transitions in Sr1−xCaxTiO3 (x=0.04, 0.06, and 0.12)

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Low-temperature phase transformations in weakly doped quantum paraelectrics: novel features and quantum reentrant dipolar glass state in KTa0.982Nb0.018O3

Cited by 9 publications

References 59 publications

Low temperature structural transformations of dilute KTa 1–x Nb x O 3 : x = 0.018, quantum superparaelectric or reentrant glass scenario?

Low temperature structural transformations of dilute KTa 1–x Nb x O 3 : x = 0.018, quantum superparaelectric or reentrant glass scenario?

Cathodoluminescence from mixed KTaO3‐KNbO3 crystals

A combined X-ray diffraction and Raman scattering study of the phase transitions in Sr1−xCaxTiO3 (x=0.04, 0.06, and 0.12)

Contact Info

Product

Resources

About

Low temperature structural transformations of dilute KTa _1–x Nb _x O ₃ : x = 0.018, quantum superparaelectric or reentrant glass scenario?

Low temperature structural transformations of dilute KTa _1–x Nb _x O ₃ : x = 0.018, quantum superparaelectric or reentrant glass scenario?

Cathodoluminescence from mixed KTaO₃‐KNbO₃ crystals