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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Mean polarizability of molecules and anisotropy of the Lorentz tensor upon a nematic-smectic a phase transition: Their behavior in a homologous series
Место публикации : Russ. J. Phys. Chem. A: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 86, Is. 5. - P.720-728. - ISSN 0036-0244, DOI 10.1134/S0036024412050044
Примечания : Cited References: 37
Предметные рубрики: CHOLESTERIC LIQUID-CRYSTALS
REFRACTIVE-INDEX DATA
A PHASE
MESOMORPHIC PROPERTIES
ORIENTATIONAL ORDER
OPTICAL ANISOTROPY
LOCAL-FIELD
POLYMORPHISM
TEMPERATURE
A-monotone
Alkyl chain
Experimental values
Homologous series
Homologues
Limiting values
Lorentz
Mesophases
Molecular core
Molecular polarizabilities
Nematic
Orientational order parameters
Polarizabilities
Polarizability density
Quadratic dependence
A-monotone
Smectic
Smectic phase
Smectic phasis
Smectic-A phasis
Ключевые слова (''Своб.индексиров.''): molecular polarizability--anisotropy--phase transition--nematic--smectic--homologues
Аннотация: Experimental values of the mean polarizability of molecules, (gamma) over bar, and components of the Lorentz tensor, L-j, in the nematic and smectic A phases are obtained for a homologous series of n-alkyl-p-(4-ethoxybenzylideneamino)-alpha-methylcinnamates. Dependences of the (gamma) over bar and L-j values on the mesophase temperature, the orientational order parameter S of molecules, and the number n in the homologous series are revealed. The quadratic dependence of (gamma) over bar (S) in the nematic and smectic phases is established that is invariant with respect to the nematic-smectic A transition. Polarizability densities of the molecular core and the alkyl chain are found from the monotone decreasing dependence (gamma) over bar (n)/v (where v is volume per one molecule) in the smectic phase. The presence (or absence) of the odd-even alternation of L-j(n) in the nematic (smectic) phase is shown. A monotone decrease in the Lorentz tensor anisotropy L with an increase in n is revealed in the smectic phase, and limiting values L-j(n - infinity) are determined.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : New features of a smectic-A-crystal-B phase transition in a homologous series of liquid crystals
Место публикации : JETP Letters. - 2014. - Vol. 99, Is. 3. - P.158-163. - ISSN 0021-3640, DOI 10.1134/S0021364014030047. - ISSN 1090-6487
Примечания : Cited References: 21
Предметные рубрики: POLARIZABILITY
POLYMORPHISM
ANISOTROPY
MOLECULES
BEHAVIOR
Аннотация: The components L j of the Lorentz tensor and the polarizability density of molecules G in the smectic-A and crystalline-B phases have been determined for homologues of the series of alkyl-p-(4-alkoxybenzylideneamino-)cinnamates. The quantity L j (G) in both phases is a linear (quadratic) function of the orientational order parameter of molecules S, which is invariant (noninvariant) with respect to the A-B transition, which is manifested in the form of jumps δL j and δG and enhancement of the G(S) dependence. An increase in the length of terminal molecular chains and weakening of interlayer correlation of molecules are accompanied by strengthening of the A-B transition of the first order and G(S) dependences in both phases together with an increase in δL j and δG. Change δG and dependence G(S) in the B phase are related to change in the conformation (flattening) of aromatic molecular cores.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Cheng F., Xia, Zhiguo, Molokeev M. S., Jing X.
Заглавие : Effects of composition modulation on the luminescence properties of Eu3+ doped Li1-xAgxLu(MoO4)2 solid-solution phosphors
Место публикации : Dalton Trans.: Royal Society of Chemistry, 2015. - Vol. 44, Is. 41. - P.18078-18089. - ISSN 1477-9226, DOI 10.1039/c5dt02760h
Примечания : Cited References: 42. - The present work was supported by the National Natural Science Foundations of China (Grant No. 51272242, 51572023, 51511130035), Natural Science Foundations of Beijing (2132050), the Program for New Century Excellent Talents in University of Ministry of Education of China (NCET-12-0950), Beijing Nova Program (Z131103000413047), Beijing Youth Excellent Talent Program (YETP0635), the Funds of the State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences (RERU2015022), and the excellent tutor section of the Fundamental Research Funds for the Central Universities of China University of Geosciences, Beijing (2-9-2015-028). This work was also partly supported by the Russian Foundation for Basic Research (Grant No. 15-52-53080 GFEN_a).
Предметные рубрики: RED PHOSPHORS
PHOTOLUMINESCENCE PROPERTIES
ENERGY-TRANSFER
WHITE LEDS
IONS
NA
POLYMORPHISM
TUNGSTATES
RELAXATION
MOLYBDATES
Аннотация: Double molybdate scheelite-type solid-solution phosphors Li1−xAgxLu1−y(MoO4)2:yEu3+ were synthesized by the solid state reaction method, and their crystal structures and luminescence properties were investigated in detail. The composition modulation and structural evolution of this series of samples were studied and the selected AgEu(MoO4)2, AgLu(MoO4)2, LiLu(MoO4)2 and LiEu(MoO4)2 phases were analyzed based on the Rietveld refinement. Depending on the variation of the Li/Ag ratio in Li1−xAgxLu1−y(MoO4)2:yEu3+ phosphors, the difference in the luminescence properties of Li1−xAgxLu1−y(MoO4)2:yEu3+ phosphors was ascribed to two factors, one reason could be assigned to the coupling effect and the nonradiative transition between the energy levels of LixAg1−xLu(MoO4)2 matrices and the activator Eu3+, another could be due to the near ultraviolet energy absorption and transmission efficiency between the charge-transfer (CT) band of O2−–Mo6+ and the 4f → 4f emissive transitions of Eu3+. The ultraviolet-visible diffuse reflection spectra (UV-vis DRS) and Raman spectra analysis were also used to verify the above mechanism.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Udod L. V., Sitnikov M. N., Molokeev M. S., Tarasova L. S., Yanushkevich K. I.
Заглавие : Magnetic, dielectric, and transport properties of bismuth pyrostannate Bi2(Sn0.9Mn0.1)2O7
Коллективы : Russian Foundation for Basic Researchers; Government of the Krasnoyarsk Region; Krasnoyarsk regional Foundation for Support of Scientific and Scientific-Engineering activity [18-52-00045 Bel_a]
Место публикации : Phys. Solid State. - 2017. - Vol. 59, Is. 11. - P.2268-2273. - ISSN 1063-7834, DOI 10.1134/S1063783417110038. - ISSN 1090-6460(eISSN)
Примечания : Cited References:20. - This work was supported by the Russian Foundation for Basic Researchers, the Government of the Krasnoyarsk Region, the Krasnoyarsk regional Foundation for Support of Scientific and Scientific-Engineering activity in the framework of the scientific projects no. 18-52-00045 Bel_a.
Предметные рубрики: BI2SN2O7
POLYMORPHISM
DIFFRACTION
Аннотация: The effect of replacing manganese ions on the structural, dielectric, transport, and magnetic properties of Bi2(Sn0.9Mn0.1)2O7 has been studied and the correlation between them has been determined. The change in the type of thermal processes and the thermopower sign upon polymorphous transitions were detected by differential scanning calorimetry. The paramagnetic Curie temperature and the antiferromagnetic interaction were determined in the martensite and austenite phases. The type of current carriers has been established.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Likhacheva A. Y., Goryainov S. V., Krylov A. S., Bul'bak T. A., Prasad PSR
Заглавие : Raman spectroscopy of natural cordierite at high water pressure up to 5?GPa
Место публикации : J. Raman Spectrosc.: Wiley-Blackwell, 2012. - Vol. 43, Is. 4. - P.559-563. - ISSN 0377-0486, DOI 10.1002/jrs.3060
Примечания : Cited References: 38. - We greatly appreciate the critical comments of Prof. R. Kaindl and an anonymous reviewer on this work, and we thank Dr G. Lepezin for providing the cordierite sample. This work was supported by RFBR grant 11-05-01121-a.
Предметные рубрики: SINGLE-CRYSTAL STRUCTURE
X-RAY
CHANNEL H2O
BEHAVIOR
SPECTRA
CO2
POLYMORPHISM
DIFFRACTION
CHEMISTRY
CAVITIES
Ключевые слова (''Своб.индексиров.''): cordierite--raman spectroscopy--high pressure--phase transition
Аннотация: The high-pressure behaviour of cordierite, a widespread ring aluminosilicate with channels incorporating fluid compounds (H2O, CO2), is characterized by the absence of phase transitions up to 2.5 GPa. However, the distortion of the ring tetrahedra observed previously at 2.3 GPa is supposed to introduce a phase transition at higher pressure, which has not been checked so far. This work presents a high-pressure Raman spectroscopic study of natural cordierite compressed in water medium up to 4.7 GPa in a diamond anvil cell. At P  4 GPa, a disordering of both the framework and intrachannel H2O subsystem is apparent from significant broadening of Raman peaks and the evolution of short-range order parameters. This is followed by abrupt shifts of the framework and O–H stretching modes at about 4.5 GPa, indicating a first-order phase transition. Its reversibility is seen from the recovery of the initial spectrum at P  3 GPa. The shift amplitudes of different framework modes indicate the predominance of distortion over contraction of the framework polyhedra upon this transition. The disordering of the H2O subsystem in the high-pressure phase is likely a consequence of distortion of the channel-forming framework elements, which is supposed to be a driving force of this transition. Copyright © 2011 John Wiley & Sons, Ltd.
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