Structural phase transition and dielectric relaxation in Pb(Zn1/3Nb2/3)O3 single crystals

The structure and the dielectric properties of Pb(Zn1/3Nb2/3)O3 (PZN) crystal have been investigated by means of high-resolution synchrotron x-ray diffraction (with an x-ray energy of 32 keV) and dielectric spectroscopy (in the frequency range of 100 Hz - 1 MHz). At high temperatures, the PZN crystal exhibits a cubic symmetry and polar nanoregions inherent to relaxor ferroelectrics are present, as evidenced by the single (222) Bragg peak and by the noticeable tails at the basis of the peak. At low temperatures, in addition to the well-known rhombohedral phase, another low-symmetry, probably ferroelectric, phase is found. The two phases coexist in the form of mesoscopic domains. The para- to ferroelectric phase transition is diffused and observed between 325 and 390 K, where the concentration of the low-temperature phases gradually increases and the cubic phase disappears upon cooling. However, no dielectric anomalies can be detected in the temperature range of diffuse phase transition. The temperature dependence of the dielectric constant show the maximum at higher temperature (Tm = 417 - 429 K, depending on frequency) with the typical relaxor dispersion at T < Tm and the frequency dependence of Tm fitted to the Vogel-Fulcher relation. Application of an electric field upon cooling from the cubic phase or poling the crystal in the ferroelectric phase gives rise to a sharp anomaly of the dielectric constant at T 390 K and diminishes greatly the dispersion at lower temperatures, but the dielectric relaxation process around Tm remains qualitatively unchanged. The results are discussed in the framework of the present models of relaxors and in comparison with the prototypical relaxor ferroelectric Pb(Mg1/3Nb2/3)O3.Comment: PDF file, 13 pages, 6 figures collected on pp.12-1

Ferroelectric Dynamics in the Perovskite Relaxor PMN

We review results obtained from recent neutron scattering studies of the lead-oxide class of perovskite relaxors PMN and PZN. A ferroelectric soft mode has been identified in PMN at 1100 K that becomes overdamped near 620 K. This is the same temperature at which polar nanoregions (PNR) begin to form, denoted by Td, and suggests that a direct connection exists between the soft mode and the PNR. The appearance of diffuse scattering intensity at Td reported by Naberezhnov et al. lends further support to this picture. At lower temperature the soft mode in PMN reappears close to Tc = 213 K (defined only for E > Ec). These results are provocative because the dynamics below Tc are characteristic of an ordered ferroelectric state, yet they occur in a system that remains cubic on average at all temperatures. We discuss a coupled-mode model that successfully describes these data as well as those from earlier lattice dynamical studies of other perovskites such as BaTiO3.Comment: 10 pages, 7 figures, Conference - Fundamental Physics of Ferroelectrics 200

The Russian consumer sector: estimation technology

The article describes the methodology for estimating the Russia’s consumer sector and the effect of its application. The monitoring procedure of the Russian consumer sector groups indicators into two units: the unit of the estimation of consumer goods and the services market estimation unit. The estimation unit of consumer goods is composed of two modules: food products and non-food products. This module offers two components that provide an estimation of the consumer sector: marketing (estimates the accessibility of retail trade and services for end users) and production (estimates the domestic manufacture). The results of the estimation show general improvements in the consumer sector in the period of 2000–2014, but overall development is evaluated as low. The analysis revealed that the financing is growing faster than the quality indices of development. As an example, the financing of agriculture has increased by 1.5 times over 15 years (against comparable prices from 2000), while agricultural production has not changed. Another most pressing challenge is the weak differentiation of the Russian economy, as evidenced by the low rates of non-food production (availability of non-foods of own production remains at a low level and averages 20 %). The results of the estimation suggest the need to reform the regulation of the sector primarily concerning priorities for its development and improvement of financial and economic mechanisms to achieve them.The research has been supported by the Russian Science Foundation Gran, the project № 15–18–10014 " Projection of optimal socio-economic systems in the turbulence of external and internal environment"

Relative value-relevance of accounting measures based on Chinese Accounting Standards and International Financial Reporting Standards

Purpose – The purpose of this paper is to investigate the relative value relevance of accounting measures based on Chinese Accounting Standards (CAS) and International Financial Reporting Standards (IFRS) in relation to both A-share and B-share markets during three distinct phases (1994-1997, 1998-2000 and 2001-2004) over which CAS were progressively harmonized with IFRS. Design/methodology/approach – Using data for 86 Chinese listed companies which issued both A- and B-shares, the authors employ the price model to test for the association between CAS-based and IFRS-based accounting information, and A-share and B-share prices. The J-test was employed to determine the relative value relevance of the information based on the two sets of accounting standards. Findings – Overall, the authors find that for both the A-share and B-share markets, both CAS-based and IFRS-based accounting information are value relevant, but IFRS-based information is more value relevant than the CAS-based information. However, the magnitude of the differences between the explanatory powers of the CAS- and IFRS-based accounting information narrowed significantly in the 2001-2004 period in both the A-share and B-share markets. The results are robust to the deflator used and the stock exchange on which the companies are listed. Practical implications – The results have implications for China and other transitional economies attempting to integrate IFRS with a uniform accounting system. Originality/value – The paper provides the first comprehensive empirical evidence as to whether or not the progressive harmonization of CAS with IFRS improved the value relevance of CAS-based accounting in China and contributes to the debate on the (ir)relevance of IFRS in emerging and transitional economies

Electronic Transport on the Shastry-Sutherland Lattice in Ising-type Rare Earth Tetraborides

In the presence of a magnetic field frustrated spin systems may exhibit plateaus at fractional values of saturation magnetization. Such plateau states are stabilized by classical and quantum mechanisms including order-by-disorder, triplon crystallization, and various competing order effects. In the case of electrically conducting systems, free electrons represent an incisive probe for the plateau states. Here we study the electrical transport of Ising-type rare earth tetraborides $R$B$_4$ ($R=$Er, Tm), a metallic Shastry-Sutherland lattice showing magnetization plateaus. We find that the longitudinal and transverse resistivities reflect scattering with both the static and dynamic plateau structure. We model these results consistently with the expected strong uniaxial anisotropy in a quantitative level, providing a framework for the study of plateau states in metallic frustrated systems.Comment: 18 pages, 5 figure