Nanodomain structures formation during polarization reversal in uniform electric field in strontium barium niobate single crystals

We have studied the ferroelectric nanodomain formation in single crystals of strontium barium niobate Sr 0.61Ba 0.39Nb 2O 6 using piezoelectric force microscopy and Raman confocal microscopy. The nanodomain structures have been created by application of the uniform electric field at room temperature. Four variants of nanodomain structure formation have been revealed: (1) discrete switching, (2) incomplete domain merging, (3) spontaneous backswitching, and (4) enlarging of nanodomain ensembles. Kinetics of the observed micro- and nanodomain structures has been explained on the basis of approach developed for lithium niobate and lithium tantalate crystals. © 2012 American Institute of Physics

Nanodomain structures formation during polarization reversal in uniform electric field in strontium barium niobate single crystals

We have studied the ferroelectric nanodomain formation in single crystals of strontium barium niobate Sr 0.61Ba 0.39Nb 2O 6 using piezoelectric force microscopy and Raman confocal microscopy. The nanodomain structures have been created by application of the uniform electric field at room temperature. Four variants of nanodomain structure formation have been revealed: (1) discrete switching, (2) incomplete domain merging, (3) spontaneous backswitching, and (4) enlarging of nanodomain ensembles. Kinetics of the observed micro- and nanodomain structures has been explained on the basis of approach developed for lithium niobate and lithium tantalate crystals. © 2012 American Institute of Physics

Tip-induced domain growth in the non-polar cuts of SBN:Ce single crystals

The local switching by conductive tip of scanning probe microscope was studied in the non-polar cuts of Ce-doped Sr0.61Ba0.39Nb2O6 single crystals after creation of the single-domain state. The switched domains possessed the egg-shaped heads and wedge-like tails. The dependences of lengths of the domain head and tail and width of the domain head on the voltage and pulse duration were derived. The start voltage for growth of the domain tail was revealed. The fast relaxation of the domain head and slow relaxation of the domain tail were observed. The model of the forward domain growth by step generation and kink motion was used for explanation of the experimental results. The obtained knowledge can be used for the domain engineering in ferroelectrics. © Published under licence by IOP Publishing Ltd.Russian Science Foundation, RSF: 19-72-00008The equipment of the Ural Centre for Shared Use “Modern nanotechnology” Ural Federal University was used. The research was made possible by the Russian Science Foundation (grant № 19-72-00008)

Temperature Effect on the Stability of the Polarized State Created by Local Electric Fields in Strontium Barium Niobate Single Crystals

AbstractThe stability of ferroelectric domain patterns at the nanoscale has been a topic of much interest for many years. We investigated the relaxation of the polarized state created by application of a local electric field using a conductive tip of a scanning probe microscope for the model uniaxial relaxor system SrxBa1−xNb2O6 (SBN) in its pure and Ce-doped form. The temporal relaxation of the induced PFM contrast was measured at various temperatures. The average value of the induced contrast decreases during heating for all investigated crystals. Below the freezing temperature the induced state remains stable after an initial relaxation. Above the freezing temperature the induced state is unstable and gradually decays with time. The stability of the induced state is strongly affected by the measuring conditions, so continuous scanning results in a faster decay of the poled domain. The obtained effects are attributed to a decrease of the induced polarization and backswitching of the polarized area under the action of the depolarization field.</jats:p

STUDY OF 3D-KINETICS OF DOMAIN STRUCTURE DURING POLARIZATION REVERSAL IN SBN SINGLE CRYSTALS BY SECOND HARMONIC GENERATION MICROSCOPY

The 3D domain structure kinetics in SBN single crystals was investigated. Domain imag-ing in the crystal bulk was realized by Čerenkov-type second harmonic generation micros-copy. Three types of domains have been revealed: domain with a broad domain boundary, cylindrical domain and conical domain.Благодарности: Исследование выполнено за счет гранта Российского научного фонда (проект № 19-72-00008). Использовано оборудование УЦКП «Современные нанотехнологии» УрФУ

Androgen receptor gene microsatellite polymorphism is associated with muscle mass and strength in bodybuilders and power athlete status

Background: The androgen receptor (AR) gene contains a polymorphic trinucleotide (CAG) microsatellite repeat sequence (short or long alleles) that has been associated with fat-free mass in untrained men, which needs to be replicated in athletic cohorts. Aim: The purpose of this study was to explore the AR (CAG) polymorphism in trained individuals. Subjects and methods: A total of 61 professional bodybuilders (40 males, 21 females), 73 elite male sprinters and weightlifters and 186 male controls were enrolled in this study. The influence of the AR (CAG) polymorphism on muscle mass and strength was assessed in bodybuilders, while the frequencies of AR (CAG) alleles were compared between power athletes and non-athletes. Results: The polymorphism was associated with anthropometric and strength measurements in bodybuilders of both genders. Those with ≥21 CAG repeats (i.e. carriers of long alleles) exhibited greater (p < 0.05) body mass index, absolute muscle mass, arm/thigh circumference and upper/lower limb strength compared to those with <21 CAG repeats. Furthermore, carriers of ≥21 CAG repeats were more frequent among power athletes compared to controls (p = 0.0076). Conclusions: Long alleles of the AR (CAG) polymorphism were associated with greater muscle mass and strength in bodybuilders, and power athlete status

Formation of self-assembled nanodomain structures in single crystals of uniaxial ferroelectrics lithium niobate, lithium tantalate and strontium–barium niobate

The formation and evolution of the self-assembled nanodomain structures during polarization reversal have been comparatively analyzed in single crystals of various uniaxial ferroelectrics: LiNbO3 (LN), LiTaO3 (LT) and SrxBa1-xNb2O6 (SBN). Several experimental methods have been used for visualization of the micro- and nanodomain patterns. The static domain images have been obtained by optical microscopy and piezoresponse force microscopy. The Raman confocal microscopy allowed us to obtain the domain images in the bulk. The equilibrium slow switching with effective screening resulted in growth of polygon-shaped micro-domains: hexagons in LN, triangles in LT and squares in SBN, which corresponds to crystal symmetry. Switching in nonequilibrium conditions (noneffective screening of depolarization field) brings to appearance of similar nanodomain structures in all studied crystals as a result of different processes: (1) formation of nanodomain ensembles, (2) discrete switching, (3) incomplete merging and (4) spontaneous backswitching