Conduction mechanism of metal-TiO2–Si structures

The conduction model has been proposed for the metal-TiO2–Si (MIS) structures. Rutile films have been prepared on Si substrates by magnetron sputtering of TiO2 target and annealing in the air at temperatures T = 800 and 1050 K. The current-voltage (CVC) and capacitance-voltage characteristics of the structures have been measured over the range of T = 283–363 K. At positive potentials on the gate, the conductivity of the MIS structures is determined by the space charge-limited current in the dielectric layer

Conduction mechanism of metal-TiO2-Si structures

The influence of annealing of titanium oxide films on the currents of metal-TiO2-n-Si structures was investigated. It has been shown that regardless of the annealing temperature the conductivity of structures at positive potentials on the gate is determined by currents limited by the space charge in the dielectric with traps exponentially distributed on energy. At negative potentials the main contribution to the current is the thermal generation of charge carriers in the space charge region in the silicon. Interface properties of TiO2-n-Si depend on the structural and phase state of the titanium oxide film which are determined by the annealing temperature

Атрибутные аннотации и их применение в дедуктивной верификации C-программ

In this paper a new kind of annotations, called attribute annotations, and the methodology for their application in a deductive program verification are proposed. A collection of annotating attributes for the subset C-kernel of the C language is described, and on their base two versions of axiomatic semantics of C-kernel - forward semantics and mixed forward semantics - are presented.Предложен новый вид аннотаций, называемых атрибутными аннотациями, и методология их применения в дедуктивной верификации программ. Описана коллекция аннотирующих атрибутов для подмножества C-kernel языка C и на их основе представлены два варианта аксиоматической семантики языка C- kernel - семантика прямого прослеживания и смешанная семантика прямого прослеживания

Integration of first-principles methods and crystallographic database searches for new ferroelectrics: Strategies and explorations

In this concept paper, the development of strategies for the integration of first-principles methods with crystallographic database mining for the discovery and design of novel ferroelectric materials is discussed, drawing on the results and experience derived from exploratory investigations on three different systems: (1) the double perovskite Sr(Sb$_{1/2}$Mn$_{1/2}$)O$_3$ as a candidate semiconducting ferroelectric; (2) polar derivatives of schafarzikite $M$Sb$_2$O$_4$; and (3) ferroelectric semiconductors with formula $M_2$P$_2$(S,Se)$_6$. A variety of avenues for further research and investigation are suggested, including automated structure type classification, low-symmetry improper ferroelectrics, and high-throughput first-principles searches for additional representatives of structural families with desirable functional properties.Comment: 13 pages, 5 figures, 4 table

Exploration of structural, thermal, vibrational and spectroscopic properties of new noncentrosymmetric double borate Rb3NdB6O12

New noncentrosymmetric rare earth borate Rb3NdB6O12 is found in the ternary system Rb2O–Nd2O3–B2O3. The Rb3NdB6O12 powder was fabricated by solid state synthesis at 1050 K for 72 h and the crystal structure was obtained by the Rietveld method. Rb3NdB6O12 crystallized in space group R32 with unit cell parameters a = 13.5236(4), c = 31.162(1) Å, Z = 3. From DSC measurements, the reversible phase transition (I type) in Rb3NdB6O12 is observed at 852–936 K. The 200 μm thick tablet is transparent over the spectral range of 0.3–6.5 μm and the band gap is found as Eg ∼ 6.29 eV. Nonlinear optical response of Rb3NdB6O12 tested via SHG is estimated to be higher than that of K3YB6O12. Blue shift of Nd luminescent lines is found in comparison with other borates. The vibrational parameters of Rb3NdB6O12 are evaluated by experimental methods

The crystal growth and properties of novel magnetic double molybdate RbFe5_{5}(MoO4_{4})7_{7} with mixed Fe3+^{3+}/Fe2+^{2+}states and 1D negative thermal expansion

Single crystals of new compound RbFe$_5$(MoO$_4$)$_7$ were successfully grown by the flux method, and their crystal structure was determined using the X-ray single-crystal diffraction technique. The XRD analysis showed that the compound crystallizes in the monoclinic space group P21/m, with unit cell parameters a = 6.8987(4), b = 21.2912(12) and c = 8.6833(5) Å, β = 102.1896(18)°, V = 1246.66(12) Å$^3$, Z (molecule number in the unit cell) = 2, R-factor (reliability factor) = 0.0166, and T = 293(2) K. Raman spectra were collected on the single crystal to show the local symmetry of MoO$_4$ tetrahedra, after the confirmation of crystal composition using energy dispersive X-ray spectroscopy (EDS). The polycrystalline samples were synthesized by a solid-state reaction in the Ar atmosphere; the particle size and thermal stability were investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) analyses. The compound decomposes above 1073 K in an Ar atmosphere with the formation of Fe(III) molybdate. The thermal expansion coefficient along the c direction has the value α = −1.3 ppm K$^{−1}$ over the temperature range of 298–473 K. Magnetic measurements revealed two maxima in the magnetization below 20 K, and paramagnetic behavior above 50 K with the calculated paramagnetic moment of 12.7 μB per formula unit is in good agreement with the presence of $_3$Fe$^{3+}$ and $_2$Fe$^{3+}$ in the high-spin (HS) state. The electronic structure of RbFe5(MoO4)7 is comparatively evaluated using X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations

Верификация C-программ в мультиязыковой системе СПЕКТР

This paper presents the expendable multi-language analysis and verication system SPECTRUM, which is being developed within the framework of the project SPEC- TRUM. The project prospects are discussed using the example of C program verication. The project aims at the development of a new integrated approach to program verica- tion which will allow the integration, unication and combination of program verication techniques together with accumulation and reuse of knowledge about them. One of the project features consists in the use of the specialized executable specication language Atoment. This language provides a unied format to represent both verication meth- ods and data for them (program models, annotations, logic formulas). The C-targeted component of the SPECTRUM system is based on our two-level C program verication method. This method represents a good illustration of the integrated approach, since it provides a complex C program verication that combines operational, axiomatic and transformational approaches.Представлена расширяемая мультиязыковая система анализа и верификации СПЕКТР, разрабатываемая в рамках одноименного проекта, и показаны перспективы ее использования на примере верификации C-программ. Проект СПЕКТР направлен на создание нового интегрированного подхода к верификации императивных программ, который позволяет интегрировать, унифицировать и комбинировать методы и техники верификации императивных программ, накапливать и использовать знания о них. Особенностью подхода является использование специализированного языка выполнимых спецификаций Atoment для разработки средств верификации программ, который позволяет представить в едином унифицированном формате как методы и техники верификации, так и данные для них (программные модели, аннотации, логические формулы). C-компонента системы СПЕКТР использует двухуровневый метод верификации C-программ. Этот метод является хорошей иллюстрацией интегрированного подхода, поскольку он обеспечивает комплексную верификацию C-программ, базирующуюся на комбинации операционного, аксиоматического и трансформационного подходов