A comparative study of structural and electrical properties in lead-free BCZT ceramics: Influence of the synthesis method

In the present work, various grain size phenomena were studied in promising lead-free piezoelectric ceramics (Ba0.85Ca0.15) (Zr0.10Ti0.90)O3 fabricated via chemical and conventional oxide methods. Phase composition was ascertained by the Rietveld refinement. Average grain size estimated from the microstructure was ∼1.5 μm in the sol-gel derived ceramic (SG-BCZT) which was much smaller than that obtained in coarse grained (∼27 μm) sample prepared by solid state method (SS-BCZT). Systematic investigation of various functional properties viz. dielectric, ferroelectric, piezoelectric and impedance emphasized the profound influence of grain size effects. The increase in grain boundary volume fraction enhanced diffuseness while lowered the dielectric peak in SG-BCZT. Similarly, increase in elastic stiffness and progressive hindrance to domain wall movements, resulted in a decrease of the remnant polarization and the associated piezoelectric charge coefficient values in small-grained SG-BCZT sample. Accordingly, higher Young's modulus value of 158.3 GPa was observed in SG-BCZT as compared to 117.9 GPa in SS-BCZT. Local-area piezoresponse force microscopy (PFM) images revealed lamellar domains with periodicity 250 ± 90 nm in SS-BCZT while small sized fractal-like irregular domains with an estimated domain width of 150 ± 60 nm were registered in SG-BCZT. Complex impedance spectroscopy results along with grain boundary conductivity were also guided by grain size effect. The mechanisms of grain size driven effects and their impact on the functional properties were discussed.publishe

Mn-Doped BaTiO3Ceramics: Thermal and electrical properties for multicaloric applications

Multiferroic materialsare widely used in microelectronics because they are sensitive to elastic, magnetic, and electric fields and there is an intrinsic coupling between them. In particular, transition metal-doped BaTiO3 is consideredas a viable multiferroic because of the simultaneous presence of ferroelectricity and magnetism.In this work, we study the electrical and thermal properties of Mn-doped BaTiO3 ceramics that can be used for multicaloric applications. We found that Mn doping leads to the broadening and shifting of the phase transition accompanied with simultaneous decrease of latent heat and entropy. Mn doping causes a decrease in the bulk resistivity while contact resistance remains intact. Doped ceramics can withstand high electric fields(up to 40 kV/cm) and exhibit linear I-V characteristics followed by the Schottkylimited current in contrast to earlier observations. As such, these ceramics are promising for multicaloric applications. © 2019 by the authors.Russian Science Foundation, RSF: № 18-19-00512Funding: This work was supported by the Russian Science Foundation (grant № 18-19-00512)

Development of Hydrometallurgical Process of Non-Ferrous and Rare Metals Recovery from Untraditional Mineral Raw Materials and Natural Brines

In connection with gradual lowering of supplies of tradit- ional ore raw materials involving non-ferrous and rare metals, winch is treated by well-known technologies, invo-lving into the production of untraditional, secondary and technogeneous raw materials appears to be actual task

Polarization reversal by tip of scanning probe microscope in SBN

We present the results of experimental study of the influence of initial domain state on the shape and size of isolated domains created by the conductive tip of scanning probe microscope during local polarization reversal in relaxor ferroelectric strontium barium niobate doped with nickel and cerium. The domain radius was found to increase with increasing voltage and time and depend on the initial polarization direction. Circular domains of the opposite sign were found to appear due to polarization backswitching. The obtained results can be used for practical applications of domain and domain wall engineering in ferroelectrics

Electromechanical and magnetic properties of BiFeO3-LaFeO3-CaTiO3 ceramics near the rhombohedral-orthorhombic phase boundary

BiFeO3-LaFeO3-CaTiO3 ceramics have been studied by X-ray diffraction, magnetization measurements, and piezoresponse force microscopy (PFM). The compositional ranges of the polar, antipolar, and non-polar phases have been estimated. PFM measurements testify gradual decrease of piezoelectric response in Bi(0.85-x)La(0.15)CaxFe(1-x)Ti(x)O(3) system with Ca/Ti content increase, except a narrow concentration region near polar-antipolar phase boundary where piezoelectric signal shows maximum value. It is found that increase of dopant concentration leads to apparent decrease of the off-center Bi-O displacement and, consequently, causes a reduction of piezoelectric response. It is concluded that notable remanent magnetization in polar and non-polar structural phases is a result of the Dzyaloshinsky-Moria interaction. (C) 2013 AIP Publishing LL

Macroscopic and local piezoelectric properties of Pb(Mg1/3Nb2/3)O-3-PbTiO3 single crystals exhibiting giant piezoelectric response

The temperature and bias field dependences of macroscopic, measured by pulsating load method, and local, measured by piezoresponse force microscopy, longitudinal piezoelectric responses have been studied in (001)-oriented flux-grown (1 - x) Pb(Mg1/3Nb2/3)O-3-xPbTiO(3) (0.0 <= x <= 0.29) single crystals. Both types of responses exhibit a dramatic enhancement with increasing bias fields. At the same time, their temperature maxima shift from the Vogel-Fulcher temperature to the vicinity of the dielectric permittivity maximum, where the critical point in the E-T phase diagram is located. Both datasets confirm a quasicritical nature of the giant field-induced piezoelectric response in relaxor single crystals. (C) 2013 AIP Publishing LL

Local Piezoelectric Properties of Doped Biomolecular Crystals

Piezoelectricity is the ability of certain crystals to generate mechanical strain proportional to an external electric field. Though many biomolecular crystals contain polar molecules, they are frequently centrosymmetric, signifying that the dipole moments of constituent molecules cancel each other. However, piezoelectricity can be induced by stereospecific doping leading to symme-try reduction. Here, we applied piezoresponse force microscopy (PFM), highly sensitive to local piezoelectricity, to characterize( 010) faces of a popular biomolecular material, α-glycine, doped with other amino acids such as L-alanine and L-threonine as well as co-doped with both. We show that, while apparent vertical piezoresponse is prone to parasitic electrostatic effects, shear piezoelectric activity is strongly affected by doping. Undoped α-glycine shows no shear piezoelectric response at all. The shear response of the L-alanine doped crystals is much larger than those of the L-threonine doped crystals and co-doped crystals. These observations are rationalized in terms of host–guest molecule interactions. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This work was supported by the collaborative program of the Israeli Ministry of Science with the Russian Foundation for Basic Research (RFBR), grant № 3-16492, and directly by the RFBR (grant № 19-52-06004 MNTI_a). The equipment of the Ural Center for Shared Use “Modern Nanotechnology” UrFU was used. A.K. acknowledges the Ministry of Science and Higher Education of the Russian Federation for the support under the project № 075-15-2021-588 from 1.06.2021. The work was also developed within the scope of the project CICECO at the Aveiro Institute of Materials, refs. UIDB/50011/2020 and UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology/MCTES. I.L. expresses his gratitude to the Estate of Olga Klein–Astrachan fund, grant № 721977

Imprint effect in PZT thin films at compositions around the morphotropic phase boundary

Piezoeresponse force microscopy (PFM) and local piezoresponse hysteresis loops were used to study the imprint effect in PbZr1-xTixO3 thin films at compositions around the morphotropic phase boundary (MPB). Schottky barriers and mechanical coupling between film-substrate were excluded as origin for the imprint in these films. Comparing the composition dependence of the effective d33 before poling with some reports in the literature, the existence of point defects such as complex vacancies (Vpb.., VO.. and Vpb..-VO..) and Ti3+ centers is discussed as probable origin for the imprint effect observed here. © 2016, © Taylor & Francis Group, LLC