scholarly journals Defects and Lattice Instability in Doped Lead-Based Perovskite Antiferroelectrics: Revisited

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 501
Author(s):  
Dariusz Kajewski

This paper is a summary of earlier results that have been completed with recent investigations on the nature and sequence of phase transitions evolving in the antiferroelectric PbZrO3 single crystals doped with niobium and Pb(Zr0.70Ti0.30)O3 ceramics doped with different concentration of Bi2O3. It was found that these crystals undergo new phase transitions never observed before. To investigate all phase transitions, different experimental methods were used to characterize the crystal properties. Temperature and time dependencies have been tentatively measured in a wide range, including a region above Tc, where precursor dynamics is observed in the form of non-centrosymmetric regions existing locally in crystal lattices. Also, coexistence of antiferroelectric phase and one of the intermediate phases could be observed in a wide temperature range. The phase transition mechanism in PbZrO3 is discussed, taking into account the local breaking of the crystal symmetry above Tc and the defects of crystal lattices, i.e., those generated during crystal growth, and intentionally introduced by preheating in a vacuum or doping with hetero-valent dopant.

2000 ◽  
Vol 112 (22) ◽  
pp. 9917-9928 ◽  
Author(s):  
M. P. Anisimov ◽  
J. A. Koropchak ◽  
A. G. Nasibulin ◽  
L. V. Timoshina

2021 ◽  
pp. 1-50
Author(s):  
Ge Song ◽  
Bohua Huang ◽  
Rongcai Ren ◽  
Zeng-Zhen Hu

AbstractIn this paper, the interannual variability of upper-ocean temperature in the equatorial Indian Ocean (IO) and its basin-wide connections are investigated using 58-year (1958-2015) comprehensive monthly mean ocean reanalysis data. Three leading modes of an empirical orthogonal function (EOF) analysis dominate the variability of upper-ocean temperature in the equatorial IO in a wide range of timescales. A coherent interannual band within the first two EOF modes identifies an oscillation between the zonally tilting thermocline across the equatorial IO in its peak phases and basin-wide displacement of the equatorial thermocline in its transitional phases. Consistent with the recharge oscillation paradigm, this oscillation is inherent of the equatorial IO with a quasi-periodicity around 15 months, in which the wind-induced off-equatorial Rossby waves near 5°S-10°S provide the phase-transition mechanism. This intrinsic IO oscillation provides the biennial component in the observed IOD variations. The third leading mode shows a nonlinear long-term trend of the upper-ocean temperature, including the near-surface warming along the equatorial Indian Ocean, accompanied by cooling trend in the lower thermocline originating further south. Such vertical contrary trends may lead to an enhanced stratification in the equatorial IO.


1981 ◽  
Vol 50 (10) ◽  
pp. 3187-3188 ◽  
Author(s):  
Masaru Komukae ◽  
Toshio Osaka ◽  
Yasuharu Makita ◽  
Tohru Ozaki ◽  
Kazuyuki Itoh ◽  
...  

Nature ◽  
1995 ◽  
Vol 373 (6509) ◽  
pp. 49-52 ◽  
Author(s):  
Guohua Chen ◽  
Allan S. Hoffman

2002 ◽  
Vol 12 (9) ◽  
pp. 133-138
Author(s):  
F. Nad ◽  
P. Monceau

In quasi-one-dimensional (TMTTF)2X conductors [1], where X are the various centro-symmetrical and non-centrosymmetrical anions, by study of temperature dependences of conductance G and dielectric permittivity $\varepsilon '$ at low frequencies we have found anomalies which are characteristic for phase transitions: an abrupt bend on the G(l/T) dependences with thermally activated decrease of G and sharp maxima of the E' near the charge ordering temperature corresponding to the E' divergence according to the Curie law. A number of evidences have been obtained in favor that driving force of these phase transitions is the long range correlated electron interaction yielding the charge ordering along the molecular chains (a lattice version of the Wigner crystal). The anion chains, electrically balanced with molecular chains, are of very importance in the formation and the stabilization of these new phase states. It appears that the form of charge symmetry of the anions determines to a great extent the types of the occurring transitions and the developing ground states.


Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3265 ◽  
Author(s):  
Vladimir N. Uversky

Cells are inhomogeneously crowded, possessing a wide range of intracellular liquid droplets abundantly present in the cytoplasm of eukaryotic and bacterial cells, in the mitochondrial matrix and nucleoplasm of eukaryotes, and in the chloroplast’s stroma of plant cells. These proteinaceous membrane-less organelles (PMLOs) not only represent a natural method of intracellular compartmentalization, which is crucial for successful execution of various biological functions, but also serve as important means for the processing of local information and rapid response to the fluctuations in environmental conditions. Since PMLOs, being complex macromolecular assemblages, possess many characteristic features of liquids, they represent highly dynamic (or fuzzy) protein–protein and/or protein–nucleic acid complexes. The biogenesis of PMLOs is controlled by specific intrinsically disordered proteins (IDPs) and hybrid proteins with ordered domains and intrinsically disordered protein regions (IDPRs), which, due to their highly dynamic structures and ability to facilitate multivalent interactions, serve as indispensable drivers of the biological liquid–liquid phase transitions (LLPTs) giving rise to PMLOs. In this article, the importance of the disorder-based supramolecular fuzziness for LLPTs and PMLO biogenesis is discussed.


2012 ◽  
Vol 54 (5) ◽  
pp. 930-931
Author(s):  
N. A. Spiridonov ◽  
V. M. Ishchuk ◽  
N. G. Kisel’ ◽  
V. N. Spiridonov

2020 ◽  
Vol 35 (39) ◽  
pp. 2050326
Author(s):  
Abdul Jawad ◽  
Shahid Chaudhary

Among many open questions in theoretical physics, consistent quantum gravity theory is still a major issue to be solved. Recent major works in phase transitions of black holes (BH) can be helpful for quantum interpretation of classical gravity. We study the new effective method to discuss the thermodynamic phase transitions onto well renowned regular BHs. Ordinary approaches of phase transitions depend upon equation of state and it is impossible to obtain all critical points with ordinary approaches. This study is derived from the slope of temperature versus entropy and it provides the possibility of finding all the critical points analytically. This technique provides pressure, which is different from standard relation of pressure and independent of other thermodynamical relations. We discuss some issues in ordinary methods and provide an easy approach to investigate the critical behavior of thermodynamical quantities. We find out the phase transitions points and horizon radii of non-physical range for BHs. We also use the new thermodynamical relations to briefly study well-known Joule–Thomson (JT) effect on regular BH.


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