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Effects of single particle on shape phase transitions and phase coexistence in odd-even nuclei

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Chinese Physics C 2018年第3期42卷 69-76页

作者：于向茹胡静李晓雪安思雨张宇 Department of Physics Liaoning Normal University

A classical analysis of shape phase transitions and phase coexistence in odd-even nuclei has been performed in the framework of the interacting boson-fermion model. The results indicate that the effects of a single particle may influence different types of transitions in different ways. Especially, it is revealed that phase coexistence can clearly emerge in the critical region and thus be taken as a indicator of the shape phase transitions in odd-even nuclei.

关键词： shape phase transition phase coexistence the interacting boson-fermion model

Non-equilibrium phases Formed in Cu–In–Se–Te System Synthesized by Melt-Quench Method

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Acta Metallurgica Sinica(English Letters) 2015年第5期28卷 567-579页

作者： Rangasami Chinnusamy Department of Physics Kongu Engineering College

Non-equilibrium phases formed in melt-quenched CuIn（SexTe1-x）2 system, where x = 0.1, 0.2, 0.4, 0.5, 0.6, 0.8 and 0.9, have been studied using Rietveld refinement of the crystal structure and Raman spectroscopy. Results of structure refinement have showed that all the samples, except the CuIn（Se0.1Te0.9）2, are heterogeneous. All the observed non-equilibrium phases are quaternary system and are found to have chalcopyrite structure （I42d）, in accordance with the CuInTe2-CuInSe2 phase diagram. The lattice constants deduced from the refinement have showed linear variation with Se content. A detailed analysis of the characteristic Al modes present in the Raman spectrum of individual sample has corroborated the results obtained from the structure analysis. The position of Al mode of individual phase is found to vary linearly with Se content, which suggests that CuIn（SexTe1-x）2 system exhibits single-mode behaviour.

关键词： Chalcogenides Crystal growth phase coexistence X-ray diffraction Crystal structure Raman spectroscopy

Magnetic properties of rare earth HoCrO_3 chromites

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Journal of Rare Earths 2011年第11期29卷 1060-1065页

作者：苏玉玲张金仓冯振杰李子炯沈岩曹世勋 Department of Physics Zhengzhou University of Light Industry Department of Physics Shanghai University

The temperature dependence of the magnetic properties was systemically studied by dc/ac magnetization and specific heat measurement for heavy rare earth HoCrO3 chromites.The results revealed the existence of complex phase coexistence and competitive magnetic behavior in HoCrO3 chromites.It was found that,in the region of higher temperature above 141.0 K,HoCrO3 behaved as a typical Curie-Weiss paramagnetic（PM）.And in the region of low temperature,a novel magnetization behavior was observed with negative magnetization（diamagnetism-like） characteristics under an external field of 100 Oe and M-T curves exhibited two symmetrical branches for field cooling（FC） and zero field cooling（ZFC） modes.This behavior indicated the coexistence of canted antiferromagnetic（CAFM） and weak ferromagnetic（FM） phase.These also exhibited the existence of competition mechanism below characteristic temperature TN1=141.0 K and the magnetic order of Ho ion below 7.5 K.The current complex magnetization might be attributed to the interaction between paramagnetic Ho3＋ moments and canted Cr3＋ moments.

关键词： rare earth chromites phase coexistence magnetic interaction

Effects caused by antiferroelectric nanodomains in PZT-based coarse-grained ceramics with compositions from the morphotropic boundary region

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Journal of Advanced Dielectrics 2017年第1期7卷 27-38页

作者： V.M.Ishchuk D.V.Kuzenko V.L.Sobolev Science&Technology Center\Reactivelectron"of the National Academy of Sciences of Ukraine Donetsk 83049 Ukraine Department of Physics South Dakota School of Mines&Technology Rapid CitySouth Dakota 57USA

Presented results demonstrate importance of taking into account such a phenomenon as the solid solution decomposition at the boundaries separating coexisting phases in lead zirconate-titanate-based solid solutions with compositions belonging to the morphotropic boundary region of the"temperature–composition"phase diagram.It is shown that in the local decomposition of solid solutions in the vicinity of the boundaries separating the tetragonal and rhombohedral phases in lead zirconate-titanate-based solid solutions lead to the changes of the solid solution's chemical composition and to the formation of segregates.It is also shown that the proper thermoelectric treatment of samples containing these segregates can give substantially higher values of piezoelectric parameters in the lead zirconate-titanate-based compounds.

关键词： Solid solution decomposition phase coexistence morphotropic boundary in ferroelectrics

On Stochastic Error and Computational Efficiency of the Markov Chain Monte Carlo Method

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Communications in Computational Physics 2014年第7期16卷 467-490页

作者： Jun Li Philippe Vignal Shuyu Sun Victor M.Calo Center for Numerical Porous Media King Abdullah University of Science and TechnologyThuwalSaudi Arabia Material Science and Engineering King Abdullah University of Science and TechnologyThuwalSaudi Arabia AppliedMathematics and Computational Science Earth Sciences and EngineeringKing Abdullah University of Science and TechnologyThuwalSaudi Arabia.

InMarkov ChainMonte Carlo(MCMC)simulations,thermal equilibria quantities are estimated by ensemble average over a sample set containing a large number of correlated samples.These samples are selected in accordance with the probability distribution function,known from the partition function of equilibrium state.As the stochastic error of the simulation results is significant,it is desirable to understand the variance of the estimation by ensemble average,which depends on the sample size(i.e.,the total number of samples in the set)and the sampling interval(i.e.,cycle number between two consecutive samples).Although large sample sizes reduce the variance,they increase the computational cost of the simulation.For a given CPU time,the sample size can be reduced greatly by increasing the sampling interval,while having the corresponding increase in variance be negligible if the original sampling interval is very small.In this work,we report a few general rules that relate the variance with the sample size and the sampling interval.These results are observed and confirmed numerically.These variance rules are derived for theMCMCmethod but are also valid for the correlated samples obtained using other Monte Carlo methods.The main contribution of this work includes the theoretical proof of these numerical observations and the set of assumptions that lead to them.

关键词： phase coexistence Gibbs ensemble molecular simulation Markov Chain Monte Carlo method variance estimation blocking method

Electromechanical phase transition of a dielectric elastomer tube under internal pressure of constant mass

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Theoretical & Applied Mechanics Letters 2017年第3期7卷 121-125页

作者： Song Che Tongqing Lu T.J. Wang State Key Lab for Strength and Vibration of Mechanical Structures Department of Engineering Mechanics Xi' an Jiaotong University Xi' an 710049 China

The electromechanical phase transition for a dielectric elastomer （DE） tube has been demonstrated in recent experiments, where it is found that the unbulged phase gradually changed into bulged phase. Previous theoretical works only studied the transition process under pressure control condition, which is not consistent with the real experimental condition. This paper focuses on more complex features of the electromechanical phase transition under internal pressure of constant mass. We derive the equilibrium equations and the condition for coexistent states for a DE tube under an internal pressure, a voltage through the thickness and an axial force. We find that under mass control condition the voltage needed to maintain the phase transition increases as the process proceeds. We analyze the entire process of electromechanical phase transition and find that the evolution of configurations is also different from that for pressure control condition.

关键词： phase transition Dielectric elastomer Electromechanical coupling phase coexistence

Nanostructures formation in ferroelectrics in the process of phase transformation

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Journal of Advanced Dielectrics 2014年第4期4卷 32-41页

作者： V.Ishchuk N.Spiridonov V.Sobolev Science and Engineering Center\Reaktivelektron"of the National Academy of Sciences of Ukraine 83096 Donetsk Ukraine Department of Physics South Dakota School of Mines and Technology Rapid City SD 57701USA

Received 26 June 2014;Revised 13 October 2014;Accepted 20 October 2014;Published 12 November 2014 Inhomogeneous states caused by the coexistence of the ferroelectric(FE)and antiferroelectric(AFE)phases in lead–zirconate–titanate based solid solutions have been investigated.It has been found that the domains of the FE and AFE phases with sizes of the order of 20 nm to 30 nm coexist in the bulk of the samples due to a small difference in the free energies of these phases.The coherent character of the interphase boundaries(IPBs)leads to the concentration of the elastic stresses along these boundaries.These elastic stresses cause the local decomposition of the solid solution and formation of segregates near the IPBS due to the condition that equivalent positions of the crystal lattice are occupied by the ions with different sizes.The sizes of the segregates formed in this way are of the order 8 nm to 15 nm.Some physical effects caused by the presence of these segregate nanostructures are analyzed and discussed.

关键词： Ferroelectrics antiferroelectrics phase transitions phase coexistence interdomain boundaries local decomposition of solid solutions

High performance of(KxNa1-x)0.98Li0.02(Nb0.82-yTa0.18Sby)O3 Lead-free piezoelectric ceramics

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High performance of(KxNa1-x)0.98Li0.02(Nb0.82-yTa0.18Sby)O3 ...