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Batio3 Based Materials for Piezoelectric and Electro-Optic Applications
BaTiO3 based materials for Piezoelectric and Electro-Optic Applications by Ytshak Avrahami B.Sc. Materials Science and Engineering, B.A. Physics (Cum Laude) Technion – Israel Institute of Technology, 1995 M.Sc. Materials Science and Engineering Technion – Israel Institute of Technology, 1997 SUBMITTED TO THE DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERING IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN ELECTRONIC, PHOTONIC AND MAGNETIC MATERIALS JANUARY 2003 © 2003 Massachusetts Institute of Technology All rights reserved 2 Abstract BaTiO3 based materials for Piezoelectric and Electro-Optic Applications by Ytshak Avrahami Submitted to the Department of Materials Science and Engineering on February 13, 2003 in Partial Fulfillment of the Requirements for the Degree of Doctor OF Philosophy in Electronic, Photonic and Magnetic Materials ABSTRACT Ferroelectric materials are key to many modern technologies, in particular piezoelectric actuators and electro-optic modulators. BaTiO3 is one of the most extensively studied ferroelectric materials. The use of BaTiO3 for piezoelectric applications is, however, limited due to the small piezoelectric coefficient of the room temperature-stable tetragonal phase. Furthermore, research on BaTiO3 for integrated optics applications remains sparse. In this work Zr-, Hf-, and KNb- doped BaTiO3 materials were prepared in a composition range that stabilizes the rhombohedral phase. These materials were prepared as bulk polycrystals using a standard solid-state reaction technique in order to test the piezoelectric and dielectric properties. Some compositions were then chosen for thin film deposition. The films were deposited using pulsed laser deposition on MgO and SOI substrates. Growth orientation, remnant strain and optical properties were then measured. -
1. Introduction Barium Titanate (Batio3) Is a Versatile Elctroceram
ARCHIVESOFMETALLURGYANDMATERIALS Volume 54 2009 Issue 4 B. WODECKA-DUŚ∗, D. CZEKAJ∗ FABRICATION AND DIELECTRIC PROPERTIES OF DONOR DOPED BaTiO3 CERAMICS OTRZYMYWANIE I WŁAŚCIWOŚCI DIELEKTRYCZNE DONOROWO DOMIESZKOWANEJ CERAMIKI BaTiO3 Barium titanate BaTiO3 is a common ferroelectric material which adopts the perovskite structure type ABO3. It is widely utilized to manufacture a variety of electronic components. In the present study lanthanum-doped BaTiO3 compositions with ◦ x=0.1 mol.% and x=0.3 mol.%, in Ba1−xLaxTi1−x/4O3 were prepared by free sintering method in air at temperature T=1350 C. The grain size distribution and morphology of the powders were studied as well as the X-ray diffraction analysis was performed to confirm formation of the desired crystalline structure. Temperature dependence of dielectric permittivity was studied in the temperature range of ferroelectric-paraelectric phase transition. Keywords: Ba1−xLaxTi1−x/4O3, donor doped, dielectric permittivity, ferroelectric ceramics Tytanian baru BaTiO3 jest przedstawicielem tlenowooktaedrycznych związków o strukturze krystalicznej typu perowskitu ABO3. Materiał ten charakteryzuje się wieloma interesującymi właściwościami, które można modyfikować poprzez zmianę składu chemicznego oraz optymalizację technologii otrzymywania. Przedmiotem niniejszej pracy było otrzymanie metodą swobodnego spiekania (T=1350◦C) na bazie półprzewodnikowego BaTiO3, domieszkowanego donorowo lantanem, roztworu stałego o składzie Ba1−xLaxTi1−x/4O3, dla koncentracji x=0,1 mol.% i x=0,3 mol.%. Celem zoptymalizowania warunków technologicznych przeprowadzono analizę ziarnową proszków. Wykorzy- stując metodę dyfrakcji promieni rentgenowskich (metoda XRD) zbadano strukturę krystaliczną, przeprowadzono identyfikację fazową oraz wyznaczono średni wymiar krystalitów otrzymanego roztworu stałego o różnej zawartości lantanu. Zbadano również temperaturowe zależności stałych dielektrycznych w obszarze przemiany fazowej oraz określono parametry ferroelektryczne otrzymanej elektroceramiki. -
Fluorinated Polymers As Smart Materials for Advanced Biomedical Applications
polymers Review Fluorinated Polymers as Smart Materials for Advanced Biomedical Applications Vanessa F. Cardoso 1,2,* ID , Daniela M. Correia 3,4, Clarisse Ribeiro 1,5 ID , Margarida M. Fernandes 1,5 and Senentxu Lanceros-Méndez 4,6 1 Centro/Departamento de Física, Universidade do Minho, 4710-057 Braga, Portugal; cribeiro@fisica.uminho.pt (C.R.); margaridafernandes@fisica.uminho.pt (M.M.F.) 2 CMEMS-UMinho, Universidade do Minho, DEI, 4800-058 Guimaraes, Portugal 3 Departamento de Química e CQ-VR, Universidade de Trás-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal; [email protected] 4 BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940 Leioa, Spain; [email protected] 5 CEB—Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal 6 IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain * Correspondence: [email protected]; Tel.: +351-253-60-40-73 Received: 11 January 2018; Accepted: 6 February 2018; Published: 8 February 2018 Abstract: Fluorinated polymers constitute a unique class of materials that exhibit a combination of suitable properties for a wide range of applications, which mainly arise from their outstanding chemical resistance, thermal stability, low friction coefficients and electrical properties. Furthermore, those presenting stimuli-responsive properties have found widespread industrial and commercial applications, based on their ability to change in a controlled fashion one or more of their physicochemical properties, in response to single or multiple external stimuli such as light, temperature, electrical and magnetic fields, pH and/or biological signals. In particular, some fluorinated polymers have been intensively investigated and applied due to their piezoelectric, pyroelectric and ferroelectric properties in biomedical applications including controlled drug delivery systems, tissue engineering, microfluidic and artificial muscle actuators, among others. -
Poly[4(5)-Vinylimidazole]/Polyvinylidene Fluoride Composites As Proton Exchange Membranes Jingjing Pan
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by RIT Scholar Works Rochester Institute of Technology RIT Scholar Works Theses Thesis/Dissertation Collections 4-1-2009 Poly[4(5)-vinylimidazole]/polyvinylidene fluoride composites as proton exchange membranes Jingjing Pan Follow this and additional works at: http://scholarworks.rit.edu/theses Recommended Citation Pan, Jingjing, "Poly[4(5)-vinylimidazole]/polyvinylidene fluoride composites as proton exchange membranes" (2009). Thesis. Rochester Institute of Technology. Accessed from This Thesis is brought to you for free and open access by the Thesis/Dissertation Collections at RIT Scholar Works. It has been accepted for inclusion in Theses by an authorized administrator of RIT Scholar Works. For more information, please contact [email protected]. Poly[4(5)-Vinylimidazole]/Polyvinylidene Fluoride Composites as Proton Exchange Membranes Jingjing Pan April 2009 Thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Chemistry. Approved: _______________________________________ Thomas W. Smith (Advisor) ______________________________ Paul Rosenberg (Department Head) Department of Chemistry Rochester Institute of Technology Rochester, New York 14623-5603 Copyright Release Form: INVESTIGATION OF POLY[4(5)-VINYLIMIDAZOLE] COMPOSITES AND THEIR POTENTIAL AS PROTON CONDUCTIVE MEMBRANES I, Jingjing Pan, hereby grant permission to the Wallace Memorial Library of Rochester Institute of Technology to reproduce my thesis in whole or in part. Any reproduction will not be for commercial use or profit. Jingjing Pan April, 2009 i Abstract In the present research, the morphology and thermal chemical characteristics of composite films comprised of poly(vinylidene fluoride) (PVF2) and poly[4(5)-vinylimidazole/vinylimidazolium trifluoromethylsulfonylimide] (PVIm/VIm+TFSI-]) were studied. -
Piezoelectricity in PVDF and PVDF Based Piezoelectric Nanogenerator: a Concept
IOSR Journal of Applied Physics (IOSR-JAP) e-ISSN: 2278-4861.Volume 9, Issue 3 Ver. I (May. – June. 2017), PP 95-99 www.iosrjournals.org Piezoelectricity in PVDF and PVDF Based Piezoelectric Nanogenerator: A Concept Binoy Bera1,*, Madhumita Das Sarkar2 1,2Department of computer science and engineering, West Bengal University of Technology, Kolkata – 700064, India Abstract: Polyvinylidene fluoride or simply PVDF is one of the most important semicrystalline polymers which generate piezoelectricity when a pressure or mechanical force applied on it. It has four crystalline phases α, β, ɣ and δ depending on the chain conformation structure. Among them α is non polar phase and β and ɣ are polar phase. Piezoelectricity in PVDF arises due to the β and ɣ phase formation. Several materials have been introduced for the preparation of nanogenerator. Among them PVDF (polyvinylidene fluoride) is most interesting material used in nanogenerator preparation due to its flexibility, bio- compatiable, nontoxic in nature. It is used in nanogenerator application due to its good ferroelectric, piezoelectric and pyroelectric properties. In this article we describe little bit concept about PVDF, its piezoelectricity and PVDF based nanogenerator. Application of piezoelectric nanogenerator is also briefly described here. Keywords: PVDF, nanogenerator, piezoelectricity, β phase, electrospinning, electroactive phase, Poling process. I. Introduction Polyvinylidene fluoride, or polyvinylidene difluoride, (PVDF) is a highly non- reactive thermoplastic fluoropolymer produced by the polymerization of vinylidene difluoride. PVDF has four crystalline phases α, β, ɣ and δ depending on the chain conformation. Among them α is thermodynamically most stable and non polar in nature. β and ɣ are polar phase. -
Preparation of Barium Strontium Titanate Powder from Citrate
APPLIED ORGANOMETALLIC CHEMISTRY Appl. Organometal. Chem. 13, 383–397 (1999) Preparation of Barium Strontium Titanate Powder from Citrate Precursor Chen-Feng Kao* and Wein-Duo Yang Department of Chemical Engineering, National Cheng Kung University, Tainan, 70101, Taiwan TiCl4 or titanium isopropoxide reacted with INTRODUCTION citric acid to form a titanyl citrate precipitate. Barium strontium citrate solutions were then BaTiO3 is ferroelectric and piezoelectric and has added to the titanyl citrate reaction to form gels. extensive applications as an electronic material. It These gels were dried and calcined to (Ba,Sr)- can be used as a capacitor, thermistor, transducer, TiO3 powders. The gels and powders were accelerometer or degausser of colour television. characterized by DSC/TGA, IR, SEM and BaTiO3 doped with strontium retains its original XRD analyses. These results showed that, at characteristics but has a lower Curie temperature 500 °C, the gels decomposed to Ba,Sr carbonate for positive temperature coefficient devices under and TiO2, followed by the formation of (Ba,Sr)- various conditions. TiO3. The onset of perovskite formation oc- Besides solid-state reactions, chemical reactions curred at 600 °C, and was nearly complete at have also been used to prepare BaTiO3 powder. 1 1000 °C. Traces of SrCO3 were still present. Among them the hydrolysis of metal alkoxide , The cation ratios of the titanate powder oxalate precipitation in ethanol2, and alcoholic prepared in the pH range 5–6 were closest to dehydration of citrate solution3 are among the more the original stoichiometry. Only 0.1 mol% of the attractive methods. In 1956 Clabaugh et al.4 free cations remained in solution. -
A Novel Route to Synthesis of Lead Glycolate and Perovskite Lead Titanate, Lead Zirconate, and Lead Zirconate Titanate (PZT)
36 «“√ “√«‘®—¬ ¡¢. (∫».) 7 (1) : ¡.§. - ¡’.§. 2550 A Novel Route to Synthesis of Lead Glycolate and Perovskite Lead Titanate, Lead Zirconate, and Lead Zirconate Titanate (PZT) via Sol-Gel Process π«—µ°√√¡¢Õß°√–∫«π°“√ —߇§√“–Àå‡≈¥‰°≈‚§‡≈µ·≈–‚§√ß √â“ß·∫∫ ‡æÕ√Õø ‰°µå¢Õ߇≈¥‰∑∑“‡πµ ‡≈¥‡´Õ√å‚§‡πµ ·≈– ‡≈¥‡´Õ√å‚§‡πµ‰∑∑“‡πµ ºà“π°√–∫«π°“√‚´≈-‡®≈ Nuchnapa Tangboriboon (πÿ™π¿“ µ—Èß∫√‘∫Ÿ√≥å)* Dr. Sujitra Wongkasemjit (¥√. ÿ®‘µ√“ «ß»å‡°…¡®‘µµå)** Dr. Alexander M. Jameison (¥√. Õ‡≈Á°´“π‡¥Õ√å ‡ÕÁ¡ ‡®¡‘ —π)*** Dr. Anuvat Sirivat (¥√. Õπÿ«—≤πå »‘√‘«—≤πå)**** ABSTRACT The reaction of lead acetate trihydrate Pb(CH3COO)2.3H2O and ethylene glycol, using triethylenetetramine (TETA) as a catalyst, provides, in one step, an access to a polymer-like precursor of lead glycolate [-PbOCH2CH2O-] via oxide one pot synthesis (OOPS). The lead glycolate precursor has superior electrical properties than lead acetate trihydrate, suggesting that the lead glycolate precursor can possibly be used as a starting material mixed with other precursors such as titanium glycolate and sodium tris (glycozirconate) to produce lead titanate, lead zirconate, and lead zirconate titanate by sol-gel transition process. ∫∑§¥¬— àÕ ß“π«‘®—¬π’ȉ¥â»÷°…“°“√‡°‘¥ªØ‘°‘√‘¬“√–À«à“߇≈¥Õ–´’‡µ¥‰µ√‰Œ‡¥√µ ·≈–‡Õ∑‘≈’π‰°≈§Õ≈‚¥¬„™â “√ ‰µ√‡Õ∑‘≈’π‡µµ√–¡’π‡ªìπ§–µ–≈’ µå‡æ◊ËÕ„™â„π°“√º≈‘µ “√µ—Èßµâπ‚æ≈‘‡¡Õ√å§◊Õ‡≈¥‰°≈‚§‡≈µ [-PbOCH2CH2O-] ∑ ”§’Ë ≠™π— ¥Àπ‘ ßµ÷Ë Õ¢∫«π°“√𔉪„™à „π°“√ â ߇§√“–À— å “√‰¥Õ‡≈§µ√‘ °™π‘ ¥µ‘ “ßÊà ‰¥·°â à “√‡øÕ√‚√‰¥Õå ‡≈§µ√‘ °‘ “√·Õπ‰∑‡øÕ√å‚√Õ‘‡≈§µ√‘°·≈– “√‡æ’¬‚´‰¥Õ‘‡≈§µ√‘°®“°°“√ —߇§√“–Àå¥â«¬ “√ª√–°Õ∫ÕÕ°‰´¥å‡æ’¬ß ¢—ÈπµÕπ‡¥’¬«∑’ˇ√’¬°«à“ Oxide One Pot Synthesis (OOPS) ∑”„À≥⠓√µ—Èßµâπ‡≈¥‰°≈‚§‡≈µ¡’ ¡∫—µ‘∑“߉øøÑ“ ¥’°«à“‡≈¥Õ–´’‡µ¥‰µ√‰Œ‡¥√µ πÕ°®“°π’Ȭ—ß “¡“√∂𔉪„™âº ¡°—∫ “√µ—Èßµâπ™π‘¥Õ◊ËπÊ ‡™àπ ‰∑∑“‡π’¬¡ ‰°≈‚§‡≈µ·≈–‚´‡¥’¬¡∑√’ ‰°≈‚§‡´Õ√å‚§‡πµ‡æ◊ËÕº≈‘µ‡≈¥‰∑∑“‡πµ ‡≈¥‡´Õ√å‚§‡πµ·≈–‡≈¥‡´Õ√å‚§‡πµ ‰∑∑“‡πµ ‚¥¬ºà“π°√–∫«π°“√‚´≈-‡®≈∑√“π ‘™—Ëπ Key Words : OOPS, Sol-gel process, Dielectric materials §” ”§—≠ : OOPS °√–∫«π°“√‚´≈-‡®≈ «— ¥ÿ‰¥Õ‘‡≈§µ√‘° * Ph.D. -
Bismuth Sodium Titanate Based Materials for Piezoelectric Actuators
Review Bismuth Sodium Titanate Based Materials for Piezoelectric Actuators Klaus Reichmann 1,*, Antonio Feteira 2,† and Ming Li 3,† Received: 19 October 2015; Accepted: 23 November 2015; Published: 4 December 2015 Academic Editor: Lorean Pardo 1 Institute of Chemistry and Technology of Materials, Graz University of Technology, Stremayrgasse 9, Graz 8010, Austria 2 Materials and Engineering Research Institute, Sheffield Hallam University, City Campus, Howard Street, Sheffield S1 1WB, UK; [email protected] 3 Advanced Materials Research Group, Department of Mechanical, Materials and Manufacturing Engineering, The University of Nottingham, University Park, Nottingham NG7 2RD, UK; [email protected] * Correspondence: [email protected]; Tel.: +43-316-8733-2321 † These authors contributed equally to this work. Abstract: The ban of lead in many electronic products and the expectation that, sooner or later, this ban will include the currently exempt piezoelectric ceramics based on Lead-Zirconate-Titanate has motivated many research groups to look for lead-free substitutes. After a short overview on different classes of lead-free piezoelectric ceramics with large strain, this review will focus on Bismuth-Sodium-Titanate and its solid solutions. These compounds exhibit extraordinarily high strain, due to a field induced phase transition, which makes them attractive for actuator applications. The structural features of these materials and the origin of the field-induced strain will be revised. Technologies for texturing, which increases the useable strain, will be introduced. Finally, the features that are relevant for the application of these materials in a multilayer design will be summarized. Keywords: piezoelectric actuator; multilayer; lead-free; bismuth sodium titanate 1. -
Systematic Review Protocol for the PFBA, Pfhxa, Pfhxs, PFNA, and PFDA (Anionic and Acid Forms) IRIS Assessments
EPA/635/R-20/131 IRIS Assessments Protocol www.epa.gov/iris Systematic Review Protocol for the PFBA, PFHxA, PFHxS, PFNA, and PFDA (anionic and acid forms) IRIS Assessments CASRN 335-76-2 (PFDA) CASRN 375-95-1 (PFNA) CASRN 307-24-4 (PFHxA) CASRN 355-46-4 (PFHxS) CASRN 375-22-4 (PFBA) Supplemental Information―Appendix A October 2019 Updated February 2020 (in response to public comments) This document was posted for public comment on November 8, 2019 (link to more information), and subsequently updated in response to those comments (updates are outlined in Section 12). It does not represent and should not be construed to represent any Agency determination or policy. Integrated Risk Information System Center for Public Health and Environmental Assessment Office of Research and Development U.S. Environmental Protection Agency Washington, DC Systematic Review Protocol for the PFBA, PFHxA, PFHxS, PFNA, and PFDA IRIS Assessments DISCLAIMER This document was posted for public comment on November 8, 2019 (link to more information), and subsequently updated in response to those comments (updates are outlined in Section 12). It does not represent and should not be construed to represent any Agency determination or policy. This document is a draft for review purposes only and does not constitute Agency policy. ii DRAFT―DO NOT CITE OR QUOTE Systematic Review Protocol for the PFBA, PFHxA, PFHxS, PFNA, and PFDA IRIS Assessments CONTENTS AUTHORS|CONTRIBUTORS|REVIEWERS ..................................................................................................... -
The Uses of Polyvinylidene Fluoride Based Resins in Chemical Handling Systems Denis K
INTERCORR2014_306 Copyright 2014, ABRACO Trabalho apresentado durante o INTERCORR 2014, em Fortaleza/CE no mês de maio de 2014. As informações e opiniões contidas neste trabalho são de exclusiva responsabilidade do(s) autor(es). The Uses of Polyvinylidene Fluoride based resins in Chemical Handling Systems Denis K. de Almeidaa, Fabio L. F. Paganinib, David Seilerc Abstract Polyvinylidene fluoride (PVDF) based polymer resins have been used for corrosive and chemically aggressive fluid containment since 1964. In the 1980’s copolymers of vinylidene fluoride and hexafluoropropylene (HFP) were introduced that complimented the very rigid PVDF product line with a more flexible version of PVDF. Recently, other new technologies have been introduced for PVDF where it has been functionalized which allows it to be bonded to lower cost structural polymers during processing. Additionally, recent development of special grades of PVDF allow for finely woven and non-woven chemical filtration products and the creation of reliable conductive versions. Due to special properties not found in other plastics or metals, PVDF is used extensively in the following industries: chlor-alkali containment, bromine, acid production & distribution, mining, metal preparation, petrochemical, pharmaceutical, food & beverage, semiconductor, pulp & paper, waste water treatment, and power generation. This paper will outline the use of PVDF, reactive PVDF and/or PVDF based copolymers in specific chemicals and the special corrosive conditions that can be associated with them. -
Synthesis of Barium Titanate from Titanyl Acylate Precursor by Sol-Precipitate Method Thandar Win', Kyaw Naing2 and Khin Mar Tunj
MM 1000115 Jour. Myan. Acad. Arts & Sc. 2008 Vol. VI. No. 1 Synthesis of Barium Titanate from Titanyl Acylate Precursor by Sol-precipitate Method Thandar Win', Kyaw Naing2 and Khin Mar TunJ Abstract Nanometersize barium titanates (BaTiO3:BT) powders can be obtained by sol-precipitate method in the presence of polyoxyethylene (20) sorbiton monooleate (Tween-80) as a polymeric surface modifier in a strong alkaline solution (pH > 13) . FT-IR, TG/ DTA, SEM and XRD were used to investigate the effects of the surfactant influence on the morphology of the obtained BaTiO3 powders. With adding surfactant, a slower rate of hydroiyzatibn is observed and the rate of condensation is slower. The addition of Tween-80 surfactant in general leads to the formation of smaller particle size of BaTiO3 (70-100 nm). Without adding surfactant, larger particle size of BaTiO3 (100-200 nm) was obtained. The nanometersize BaTiO3 powders were readily sintered at 1000-1200°C. Raman-active modes of tetragonal phase BT were detected from Raman spectra of BaTiO3 between 800°C to 1200°C. Key words: Barium Titanates, sol-precipitate method, Tween-80, tetragonal-phase, Raman Spectra Introduction Barium titanate crystallizes in a perovskite structure is an important electronic ceramic. Barium titanate (BaTi(>3 : BT) naoncrystals have great advantages over micrometer size ceramic powders when the thickness of a single ceramic layer decreases to less than 2fxm. Low temperature synthesis has provided on exciting possibility for high purity, homogeneous, and ultrafine BaTiO3 nonoparticles. BT nonocrystals have been synthesized by Using a hydrothermal method, sol-gel processing, the oxalate route, microwave heating, a micro-emulsion process and a polymeric precursor method. -
Thermogravimetric Study of Barium Titanate James Nicholas Lingscheit Iowa State University
Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1973 Thermogravimetric study of barium titanate James Nicholas Lingscheit Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Chemical Engineering Commons Recommended Citation Lingscheit, James Nicholas, "Thermogravimetric study of barium titanate " (1973). Retrospective Theses and Dissertations. 5029. https://lib.dr.iastate.edu/rtd/5029 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS This material was produced from a microfilm copy of the original document. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the original submitted. The following explanation of techniques is provided to help you understand markings or patterns which may appear on this reproduction. 1. The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting thru an image and duplicating adjacent pages to insure you complete continuity. 2. When an image on the film is obliterated with a large round black mark, it is an indication that the photographer suspected that the copy may have moved during exposure and thus cause a blurred image.