Recent Developments in Thermodynamic Theory of Ferroelectric Thin Films

2005 ◽  
Vol 902 ◽  
Author(s):  
Nikolay Pertsev
Keyword(s):  
Thermodynamic Formalism ◽  
Film Plane ◽  
Epitaxial Films ◽  
Thermodynamic Theory ◽  
Theoretical Studies ◽  
Structure Property ◽  
Ferroelectric Films ◽  
Structure Property Relationships ◽  
Recent Developments ◽  
Further Development

AbstractThe nonlinear thermodynamic theory of epitaxial ferroelectric films has predicted several important strain-induced phenomena, which have been already observed experimentally. This justifies further development of this theory aiming at the better understanding of the structure/property relationships in thin-film ferroelectrics. To that end, a number of new theoretical studies have been performed recently. First, the thermodynamic formalism has been extended to epitaxial films grown on dissimilar substrates inducing anisotropic strains and a shear deformation in the film plane. Second, the polarization states and dielectric properties were calculated for polydomain Pb(Zr1-xTix)O3 films deposited on cubic substrates. Third, the effect of depolarizing field on the physical properties of strained single-domain films sandwiched between continuous electrodes was described. The results of these studies will be discussed in this paper.

scholarly journals Structure–Property Relationships for Weak Ferromagnetic Perovskites

2021 ◽  
Vol 7 (8) ◽  
pp. 111
Author(s):  
Alexander Moskvin
Keyword(s):  
Optical Properties ◽  
Rare Earth ◽  
Theoretical Studies ◽  
Structure Property ◽  
Magnetoelastic Anisotropy ◽  
Structure Property Relationships ◽  
Simple Theoretical Model ◽  
Experimental And Theoretical Studies ◽  
Weak Ferromagnetic ◽  
Magnetic Sublattices

Despite several decades of active experimental and theoretical studies of rare-earth orthoferrites, the mechanism of the formation of their specific magnetic, magnetoelastic, optical, and magneto-optical properties remains a subject of discussion. This paper provides an overview of simple theoretical model approaches to quantitatively describing the structure–property relationships—in particular, the interplay between FeO6 octahedral deformations/rotations and the main magnetic and optic characteristics, such as Néel temperature, overt and hidden canting of magnetic sublattices, magnetic and magnetoelastic anisotropy, and optic and photoelastic anisotropy.

Designer Nanostructures Of Catalysts in the Environmental-HREM

1999 ◽  
Vol 5 (S2) ◽  
pp. 686-687
Author(s):  
Pratibha L. Gai
Keyword(s):  
Real Time ◽  
Selective Oxidation ◽  
Active Sites ◽  
High Resolution Electron Microscopy ◽  
Oxidation Catalysis ◽  
Atomic Scale ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Resolution Electron ◽  
Recent Developments

Major advances in the field of in situ environmental high resolution electron microscopy (EHREM) probe selective oxidation catalysis directly on the atomic scale. Dynamic gas-solid surface interactions are studied in real-time and under realistic reaction conditions to unravel atomic level insights into active sites and structure-property relationships in vital chemical and technological processes [1-3]. The recent developments include a pioneering approach with the controlled environmental cell (ECELL) facilities permanently mounted inside the EHREM [2]. Accessories have been added for simultaneous structural and compositional analyses of the reactor contents in real-time, and using atomic resolution imaging with transmission electron diffraction and parallel electron energy loss spectroscopy (PEELS). We are now developing innovative experimental methods that include very high temperature studies and combining in the same instrument facilities for both EHREM and environmental-SEM (ESEM), (EHREM-ESEM), with attractive possibilities for studying the science of selective oxidation catalysis.Alkane Catalysis, Chlorofluorocarbons and Nanotubes:In the domain of transition metal based oxides, discoveries of fundamental mechanisms underlying selective catalyzation have come from EHREM studies.

Spectroscopic Studies on the Structures of Phosphate Sealing Glasses

MRS Bulletin ◽  
1998 ◽  
Vol 23 (11) ◽  
pp. 63-67 ◽  
Author(s):  
Richard K. Brow ◽  
Todd M. Alam ◽  
David R. Tallant ◽  
R. James Kirkpatrick
Keyword(s):  
Cross Sections ◽  
Spectroscopic Studies ◽  
Phosphate Glasses ◽  
Stimulated Emission ◽  
Structure Property ◽  
Thermal Expansion Coefficients ◽  
Structure Property Relationships ◽  
Recent Developments ◽  
Expansion Coefficients ◽  
Fast Ion

Phosphate glasses generally have lower glass-transition temperatures and greater thermal-expansion coefficients than silicate and borate glasses, and so are candidate materials for specialty glass-metal sealing applications. Phosphate glasses also have desirable optical properties (rare-earth stimulated-emission cross sections, low thermo-optical coefficients, ultraviolet transparency, etc.) and so are used as laser glasses. Recent developments of novel compositions for biomedical applications and as fast-ion conductors have also revived interest in the study of phosphate glass structures.The structure/property relationships in simple phosphate glasses have not received nearly the attention paid to silicate and borate-based systems. This is partially due to the difficulty in preparing anhydrous compositions with more than 50-mol% P2O5. Ultraphosphate compositions (where the [O]/[P] ratio is less than 3) are highly reactive to ambient water. In addition because P2O5 sublimes at about 300°C, ultraphosphate glasses have not been studied to the extent that metaphosphate ([O]/[P] = 3) and polyphosphate ([O]/[P] > 3) compositions have.

scholarly journals Polyelectrolyte Gels: Fundamentals, Fabrication and Applications

Gels ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 148
Author(s):  
Nisal Wanasingha ◽  
Pramod Dorishetty ◽  
Naba K. Dutta ◽  
Namita Roy Choudhury
Keyword(s):  
Polymer Networks ◽  
Polymer Gels ◽  
Important Class ◽  
Structure Property ◽  
Polyelectrolyte Gels ◽  
Structure Property Relationships ◽  
Emerging Trends ◽  
Charge Shape ◽  
Recent Developments ◽  
Recent Attention

Polyelectrolyte gels are an important class of polymer gels and a versatile platform with charged polymer networks with ionisable groups. They have drawn significant recent attention as a class of smart material and have demonstrated potential for a variety of applications. This review begins with the fundamentals of polyelectrolyte gels, which encompass various classifications (i.e., origin, charge, shape) and crucial aspects (ionic conductivity and stimuli responsiveness). It further centralises recent developments of polyelectrolyte gels, emphasising their synthesis, structure–property relationships and responsive properties. Sequentially, this review demonstrates how polyelectrolyte gels’ flourishing properties create attractiveness to a range of applications including tissue engineering, drug delivery, actuators and bioelectronics. Finally, the review outlines the indisputable appeal, further improvements and emerging trends in polyelectrolyte gels.

scholarly journals Functional Materials Based on Cyclometalated Platinum(II) β-Diketonate Complexes: A Review of Structure–Property Relationships and Applications

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4236
Author(s):  
Ashanul Haque ◽  
Hani El Moll ◽  
Khalaf M. Alenezi ◽  
Muhammad S. Khan ◽  
Wai-Yeung Wong
Keyword(s):  
Photophysical Properties ◽  
Functional Materials ◽  
Polymeric Materials ◽  
Organometallic Complexes ◽  
Structure Property ◽  
Covalent Bonds ◽  
Ancillary Ligands ◽  
Structure Property Relationships ◽  
Materials Research ◽  
Recent Developments

Square planar organoplatinum(II) complexes have garnered immense interest in the area of materials research. The combination of the Pt(II) fragment with mono-, bi- tri- and tetradentate organic ligands gives rise to a large variety of complexes with intriguing properties, especially cyclometalated Pt(II) complexes in which ligands are connected through covalent bonds demonstrate higher stability, excellent photoluminescence properties, and diverse applications. The properties and applications of the Pt(II)-based materials can be smartly fine-tuned via a judicious selection of the cyclometalating as well as ancillary ligands. In this review, attempts have been made to provide a brief review of the recent developments of neutral Pt(II) organometallic complexes bearing bidentate cyclometalating ligands and β-diketonate ancillary ligands, i.e., (C^N)Pt(O^O) and (C^C)Pt(O^O) derivatives. Both small (monomeric, dimeric) and large (polymeric) materials have been considered. We critically assessed the role of functionalities (ligands) on photophysical properties and their impact on applications.

Structure-property relationships of PE/PP sandwiched films

1987 ◽  
Vol 45 ◽  
pp. 454-455
Author(s):  
J. Petermann ◽  
G. Broza ◽  
U. Rieck ◽  
A. Jaballah ◽  
A. Kawaguchi
Keyword(s):  
Mechanical Tests ◽  
Polymer Materials ◽  
Ionic Crystals ◽  
Structure Property ◽  
Polymer Systems ◽  
Structure Property Relationships ◽  
Oriented Films ◽  
Materials Used ◽  
Polymer Laminates ◽  
Heated Glass

Oriented overgrowth of polymer materials onto ionic crystals is well known and recently it was demonstrated that this epitaxial crystallisation can also occur in polymer/polymer systems, under certain conditions. The morphologies and the resulting physical properties of such systems will be presented, especially the influence of epitaxial interfaces on the adhesion of polymer laminates and the mechanical properties of epitaxially crystallized sandwiched layers.Materials used were polyethylene, PE, Lupolen 6021 DX (HDPE) and 1810 D (LDPE) from BASF AG; polypropylene, PP, (PPN) provided by Höchst AG and polybutene-1, PB-1, Vestolen BT from Chemische Werke Hüls. Thin oriented films were prepared according to the method of Petermann and Gohil, by winding up two different polymer films from two separately heated glass-plates simultaneously with the help of a motor driven cylinder. One double layer was used for TEM investigations, while about 1000 sandwiched layers were taken for mechanical tests.

Approaches for TEM imaging of cavitation in toughened nylon

1989 ◽  
Vol 47 ◽  
pp. 352-353
Author(s):  
Barbara A. Wood
Keyword(s):  
Morphological Characteristics ◽  
Structure Property ◽  
Polymer Systems ◽  
Selective Staining ◽  
Structure Property Relationships ◽  
Rubber Toughened ◽  
Shear Yield ◽  
Controversial Topic ◽  
Selection Of ◽  
Diamond Knife

A controversial topic in the study of structure-property relationships of toughened polymer systems is the internal cavitation of toughener particles resulting from damage on impact or tensile deformation.Detailed observations of the influence of morphological characteristics such as particle size distribution on deformation mechanisms such as shear yield and cavitation could provide valuable guidance for selection of processing conditions, but TEM observation of damaged zones presents some experimental difficulties.Previously published TEM images of impact fractured toughened nylon show holes but contrast between matrix and toughener is lacking; other systems investigated have clearly shown cavitated impact modifier particles. In rubber toughened nylon, the physical characteristics of cavitated material differ from undamaged material to the extent that sectioning of heavily damaged regions by cryoultramicrotomy with a diamond knife results in sections of greater than optimum thickness (Figure 1). The detailed morphology is obscured despite selective staining of the rubber phase using the ruthenium trichloride route to ruthenium tetroxide.

Catalyst Halogenation Enables Rapid and Efficient Polymerizations with Visible to Near-Infrared Light

2020 ◽  
Author(s):  
Alex Stafford ◽  
Dowon Ahn ◽  
Emily Raulerson ◽  
Kun-You Chung ◽  
Kaihong Sun ◽  
...  
Keyword(s):  
Near Infrared ◽  
Transient Absorption ◽  
Reaction Times ◽  
Infrared Light ◽  
Structure Property ◽  
Light Emitting ◽  
Structure Property Relationships ◽  
Nir Light ◽  
Light Intensities ◽  
Emission Quenching

Driving rapid polymerizations with visible to near-infrared (NIR) light will enable nascent technologies in the emerging fields of bio- and composite-printing. However, current photopolymerization strategies are limited by long reaction times, high light intensities, and/or large catalyst loadings. Improving efficiency remains elusive without a comprehensive, mechanistic evaluation of photocatalysis to better understand how composition relates to polymerization metrics. With this objective in mind, a series of methine- and aza-bridged boron dipyrromethene (BODIPY) derivatives were synthesized and systematically characterized to elucidate key structure-property relationships that facilitate efficient photopolymerization driven by visible to NIR light. For both BODIPY scaffolds, halogenation was shown as a general method to increase polymerization rate, quantitatively characterized using a custom real-time infrared spectroscopy setup. Furthermore, a combination of steady-state emission quenching experiments, electronic structure calculations, and ultrafast transient absorption revealed that efficient intersystem crossing to the lowest excited triplet state upon halogenation was a key mechanistic step to achieving rapid photopolymerization reactions. Unprecedented polymerization rates were achieved with extremely low light intensities (< 1 mW/cm<sup>2</sup>) and catalyst loadings (< 50 μM), exemplified by reaction completion within 60 seconds of irradiation using green, red, and NIR light-emitting diodes.

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