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Pirozerski A.L.,Saint Petersburg State University | Charnaya E.V.,Saint Petersburg State University | Baryshnikov S.V.,Blagoveschensk State Pedagogical University | Nedbai A.I.,Saint Petersburg State University | And 5 more authors.
International Journal of Applied Engineering Research | Year: 2016

A modified pulse-phase ultrasonic technique for the measurement of the ultrasound velocity is described. It was applied for studies of the temperature dependence of the longitudinal ultrasound velocity in a nanocomposite MCM-41/LiCsSO4in the temperature range 160-300 K. A local decrease of the velocity with minimum at ~195 K was observed. A qualitative explanation of this anomaly and its connection with the ferroelastic phase transition in the nanoparticles within the pores is given. It is shown that ultrasonic methods are very suitable for studies of the ferroelastic phase transitions in the nanocomposites. © Research India Publications. Source


Borisov B.F.,Saint Petersburg State University | Charnaya E.V.,National Cheng Kung University | Baryshnikov S.V.,Blagoveschensk State Pedagogical University | Pirozerskii A.L.,Saint Petersburg State University | And 4 more authors.
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2010

Acoustic studies of a nanocomposite consisted of MCM-41 molecular sieves with nanoparticles of ferroelastic LiCsSO4 within pores were carried out. The critical softening of the transverse ultrasound velocity was observed which evidenced the ferroelastic phase transition in confined particles. The transition was moved to low temperatures compared to that in bulk LiCsSO 4. It is shown that acoustic methods are very suitable to reveal the ferroelastic phase transitions under nanoconfinement. © 2010 Elsevier B.V. Source


Baryshnikov S.V.,Amur State University | Charnaya E.V.,Saint Petersburg State University | Milinskii A.Yu.,Amur State University | Antonov A.A.,Blagoveschensk State Pedagogical University | Bugaev A.S.,Moscow Institute of Physics and Technology
Composites Part B: Engineering | Year: 2015

Dielectric studies were carried out for composite ceramics (BaTiO3)x/(BiFeO3)1-x (0 < x < 1) within a temperature range 23-450°C. Linear permittivity studies at various frequencies showed the emergence of peaks near the temperatures of the ferroelectric phase transition in the BaTiO3 grains and of the antiferromagnetic phase transition in the BiFeO3 grains. The positions of the peaks did not depend visibly on frequency. The permittivity peaks near the antiferromagnetic phase transition shifted to low temperature with increasing the barium titanate fraction which suggests the reduction of the Neel temperature. The decrease in the Neel temperature in the composite ceramics was confirmed by measurements of the temperature dependence of the third harmonic generation. © 2015 Elsevier Ltd. All rights reserved. Source


Baryshnikov S.V.,Blagoveschensk State Pedagogical University | Charnaya E.V.,National Cheng Kung University | Milinskiy A.Y.,Blagoveschensk State Pedagogical University | Shatskaya Y.A.,Blagoveschensk State Pedagogical University | And 2 more authors.
Physica B: Condensed Matter | Year: 2010

Measurements of the linear permittivity and third-order harmonic generation were carried out for KNO3 loaded molecular sieves MCM-41 with pores of 37 and 26 in comparison with bulk potassium nitrate. The samples were warmed up to 423 and 463 K from room temperature. The ferroelectric phase III was shown to occur upon cooling in both nanocomposites after warming till 463 K when it emerges also in bulk KNO3. Nanoconfinement led to the pronounced broadening of the temperature range of ferroelectricity. While under the thermal conditions when phase III does not arise in bulk KNO3, ferroelectricity was found only within pores of 26 . © 2010 Elsevier B.V. All rights reserved. Source


Baryshnikov S.V.,Blagoveschensk State Pedagogical University | Charnaya E.V.,National Cheng Kung University | Charnaya E.V.,Saint Petersburg State University | Stukova E.V.,Blagoveschensk State Pedagogical University | And 2 more authors.
Ferroelectrics | Year: 2010

Studies of complex permittivity and third harmonic generation were carried out for a Rochelle salt loaded porous alumina film within a temperature range from 80 to 325 K in comparison with studies of Rochelle salt single crystals. Only one peak of real part of permittivity corresponding to the lower (re-entrant) phase transition in confined Rochelle salt was observed which temperature was reduced by 10 K compared to the relevant temperature in bulk. The upper phase transition was shifted beyond the decomposition temperature in agreement with previous findings. The amplitude of the third harmonic which correlates to the emergence of ferroelectricity was found to be enhanced above 245 K till 325 K. The results obtained evidence the strong extension of the ferroelectric phase in confined Rochelle salt due to the decrease and the increase of the lower and upper phase transition temperatures, respectively. The physical nature of such extension is discussed. Copyright © Taylor & Francis Group, LLC. Source

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