Dielectric nonlinearity of relaxor ferroelectric ceramics at low ac drives

Dielectric nonlinear response of (PbMg$_{1/3}$Nb$_{2/3}$O$_3$)$_{0.9}$(PbTiO$_3$)$_{0.1}$ (0.9PMN-0.1PT) relaxor ceramics was investigated under different ac drive voltages. It was observed that: (i) the dielectric permittivity is independent on ac field amplitude at high temperatures; (ii) with increasing ac drive, the permittivity maximum increases, and the temperature of the maximum shifts to lower temperature; (iii) the nonlinear effect is weakened when the measurement frequency increases. The influences of increasing ac drive were found to be similar to that of decreasing frequency. It is believed that the dielectric nonlinearities of relaxors at low drives can be explained by the phase transition theory of ergodic space shrinking in succession. A Monte Carlo simulation was performed on the flips of micro polarizations at low ac drives to verify the theory.Comment: Submitted to J. Phys.: Cond. Matte

Unique single-domain state in a polycrystalline ferroelectric ceramic

Non-180° ferroelectric domains are also ferroelastic domains; their existence in polycrystalline materials is to relieve internal stresses generated during solid-solid phase transitions and minimize the elastic distortion energy. Therefore, grains with random orientations in polycrystalline ceramics are always occupied by many domains, especially in the regions close to grain boundaries. In this Rapid Communication, we report the observation of a single-domain state in a BaTiO3-based polycrystalline ceramic at intermediate poling electric fields with in situ transmission electron microscopy. The grains in the virgin ceramic and under high poling fields are found multidomained. The unique single-domain state is believed to be responsible for the ultrahigh piezoelectric property observed in this lead-free composition and is suggested to be of orthorhombic symmetry for its exceptionally low elastic modulus.This article is from Physical Review B 89 (2014): 100104(R), doi: 10.1103/PhysRevB.89.100104.Posted with permission.</p

Poland and Germany, 1989-1991: The Role of Economic Factors in Foreign Policy

The Donald W. Treadgold Papers publication series was created to honor a great teacher and scholar. Donald W. Treadgold was professor of history and international studies at the University of Washington from 1949 to 1993. During that time he wrote seven books, on of which - Twentieth Century Russia - went into eight editions. He was twice editor of Slavic Review, the organ of the American Association for the Advancement of Slavic Studies, and received the AAASS Award for Distinguished Contributions to Slavic Studies, as well as the AAASS Award for Destinguished Service. Professor Treadgold molded several generations of Russian historians and contributed enormously to the field of Russian history. He was, in other ways as well, an inspiration to all who knew him. The Treadgold Papers series was created in 1993 on the occaision of Professor Treadgold's retirement, on the initiative of Professor Daniel Waugh. Professor Treadgold passed away in December 1994. The series is dedicated to the memory of a great man, publishing papers in those areas which were close to his heart

Georgia on my mind? Russian sanctions and the end of the ‘Rose Revolution’

In recent years Russia has launched a concerted effort to undermine pro-Western regimes in the former Soviet area by using economic sanctions. Most studies of this economic offensive have focused on Russia's obvious use of natural gas as a political weapon. This paper adds to that literature by showing how the Kremlin in fact uses many kinds of sanctions simultaneously. The case of Georgia illustrates this clearly. To undermine President Saakashvili Moscow used not only energy sanctions, but also trade and financial sanctions, as well as restrictions on Georgian migrant workers. As this case shows, democratic regimes may be particularly vulnerable to such economic sanctions, since even a relatively small economic decline can cause an incumbent to lose an election. The Russian effort in Georgia seems to have succeeded, as Saakashvili's party was driven from office in the 2012 and 2013 elections by Georgian Dream, a new coalition founded by Bidzina Ivanishvili, a billionaire who made his fortune in Russia. However, Ivanishvili has now found that he, too, faces Russian economic pressure

Pipeline politics: Russian energy sanctions and the 2010 Ukrainian elections

In early 2010, the ‘Orange Revolution’ in the Ukraine came to an end. The pro-Western President, Viktor Yushchenko, was replaced by the pro-Russian Viktor Yanukovych. This paper argues that Russian energy sanctions helped pave the way for Yanukovych's election. The Kremlin undermined the Ukrainian economy by exploiting the country's dependence on Russian oil and gas, imposing harsh price increases and financial terms and even cutting off supplies in 2006 and 2009. In the end, I argue, these measures fit the ‘classic model’ of economic sanctions: impose pain until the population turns against its government and removes it. Uniquely, however, this paper links sanctions to the long-standing literature on elections in the U.S. and other democracies which shows how economic decline influences voting behavior. A certain level of sanctions may cause a predictable change in election outcomes in the targeted state. This opens, I believe, an important new potential avenue in research on sanctions