G. I. Ivanova

X-ray and magnetic birefringence studies of some lanthanide metallomesogens with Schiff's base ligands

Abstract Low angle X-ray scattering studies have been used to identify the mesophase of some calamitic lanthanide mesogens as smectic A, while magnetic birefringence studies have shown a huge magnetic anisotropy for these complexes.

The synthesis of liquid crystalline lanthanide complexes and their magnetic birefringence

Liquid crystalline complexes of the type [ML(LH)2](NO3)2, where LH=C7H15O-C6H3(OH)CH=N-C18H37 and M=Gd, Dy, and La, have been obtained. All of them exhibit the SA phase and have high magnetic birefringence constants due to the association of the complexes in solution. In the case of the dysprosium derivative, the effect is much stronger (four orders of magnitude greater than the usual value) because of the high magnetic anisotropy of the particles of the complex.

Synthesis and mesogenic properties of azomethine complexes of lanthanides with alkyl sulfate anions

Liquid-crystalline cationic complexes of lanthanides with azomethines containing the alkyl sulfate anion as the counterion were synthesized. The temperatures of existence of the mesophase of the complexes with the alkyl sulfate anion were by 80–100°C lower than those of similar complexes with the Cl− and NO3− counterions.

EPR of the first Fe(III)-containing spin-crossover metallomesogens

The low-spin (LS) to high-spin (HS) transition in two mesogenic Fe(III) complexes with alkyloxysalicyliden-N′-ethyl-N-ethylendiamine as ligands is studied by electron paramagnetic resonance (EPR). The symmetrization of the crystal field around the Fe(III) ion under first heating of a polycrystalline sample from the room temperature was observed in the spectra of HS complexes. The line narrowing (from 45 to 15 mT) under the crystal-smectic phase transition is explained by the strengthening of the intermolecular exchange interaction, as a result of the structural reorganization of layers in the smectic phase. A feature of both mesogenic spin-transition systemsis an unusual field-induced spin instability which leads to the hysteresis of the HS-LS composition. This instability is detected by EPR and magnetic susceptibility methods. The alignment of systems by magnetic field in the mesophase and a complete or partial orientational order under cooling the mesophase to the glass state are the main reason for this hysteresis. The influence of EPR-silent LS complexes reveals itself in the line broadening of HS compounds’ when the temperature is lowered from 220 K.

Magnetic anisotropy of liquid crystals based on lanthanide mesogenic complexes

The values of magnetic anisotropy of smectic A-phases for a number of lanthanide complexes (LH)2LM(NO3)2, where M=Nd, Eu, Gd, Tb, Dy, Ho, and Er, and LH is a Schiffs base), were measured. These values are two orders of magnitude larger than those normally found for diamagnetic liquid crystals and are well correlated with magnetic birefringence constants and molecular mangetic anisotropy of nomesogenic lanthanide diketonates.

Preparation and liquid-crystalline properties of mono- and binuclear complexes of Fe(III) with pentadentate Schiff’s base

Liquid-crystalline mono-and binuclear complexes of Fe(III) based on pentadentate Schiff’s base, N,N′-bis(2-hydroxy-4-octadecyloxybenzyliden)-1,7-diamino-4-azaheptane, have been prepared for the first time. The effects of counterions of the binuclear complexes and of the monodentate ligand in the mononuclear complexes on formation of the mesophase as well as phase transitions temperatures and the range of the mesophase existence have been demonstrated. EPR studies have revealed the possibility of spin-crossover properties of the complexes.

Thermo- and photoinduced properties of the Fe(III) complexes with the pentadentate ligand according to the EPR data

Compounds [Fe(Salten)L]BPh4 (Salten = N,N-bis[(2-oxyphenyl)methylene]-4-azaheptane-1,7-diamine; L = Him (I) and Pic (II)) were studied by the EPR method in the temperature range from 5 to 300 K. The thermoinduced spin transition is observed in compound II. Its thermodynamic parameters and parameters of the ground electronic low-spin state were determined. The effect of decreasing the intensity of the stationary EPR signal upon laser pulse irradiation at λ = 532 nm was observed in the studied samples.

Methods of logical synthesis for library elements and blocks with regular layout structure

The paper is devoted to research and development of custom IP-blocks design methods in the form of standard elements with regular layout structure in the layers of polysilicon and diffusion. For today the leading developers of microelectronic devices continue to work out the key modules of microelectronic systems, such as core microprocessors, microcontrollers completely custom-made in a mode in which the final composition of library elements is not known beforehand, and the design is extremely low at the transistor level. However, automation of logic and layout synthesis process for a completely custom design is difficult due to significant increase in the complexity of the problem with increasing integration of microelectronic systems and decreasing the size of the standard elements to 22nm and below. The authors proposed FinFET layout design formation methods for layout synthesis of elements with a regular layout structure in layers of polysilicon and diffusion.

Simultaneous logic and layout synthesis for Fin-fet based elements with regular layout in polysilicon and diffusion

Actuality of investigation. Nowadays the leading developers of microelectronic devices continue the elaboration of completely custom-made key microelectronic systems modules, such as microprocessors cores, microcontrollers in a mode where the final composition of library elements is not known beforehand, and the design is performaning at the extremely low transistor level. However, automation of logic and layout synthesis process for a completely custom design is difficult due to significant increase of problem complexity with increasing integration of microelectronic systems and decreasing technology sizes to 22nm and below. The purpose of this paper investigation is FinFET layout generation methods for synthesis of elements with regular layout structure in polysilicon and diffusion layers for the full custom data flow.

Multi-interval static timing analysis accounting logic compatibility

The influence of technological and circuit parameters variations on the combinational circuit elements delay increases with the transistor size reduction. Delay uncertainty comes from the parameter values dispersion; therefore, it is critical to analyze the possible delay variance. This paper presents the solution to problems of complex digital circuits performance analysis with the presence of the aforementioned uncertainty. In order to account technological and circuit element parameters uncertainty we propose a method which is based on interval modeling. Unlike the traditional analysis based on the test sequence modeling with ordering events during the time, the proposed method provides space ordering, thus it offers significant accuracy increase for interval delay analysis with simultaneous input switching consideration.