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Author: Alain Girard
Publisher:
ISBN:
Category :
Languages : fr
Pages : 210
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Author: Alain Girard
Publisher:
ISBN:
Category :
Languages : fr
Pages : 210
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Book Description
Author: Alain Girard
Publisher:
ISBN:
Category :
Languages : fr
Pages : 0
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Author: Minoru Fujimoto
Publisher: Springer Science & Business Media
ISBN: 1475727259
Category : Science
Languages : en
Pages : 256
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Book Description
Intended for readers with some prior knowledge of condensed-matter physics, this text emphasises the basic physics behind spontaneous structural changes in crystals. Starting with the relevant thermodynamic principles, the author discusses the nature of order variables and their collective motion in a crystal lattice. He also goes on to describe experimental methods for modulated crystal structures and gives examples of structural changes in representative systems. Both a graduate text and reference work.
Author: Pierre Toldano
Publisher: World Scientific
ISBN: 9789810223649
Category : Science
Languages : en
Pages : 424
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Book Description
This book deals with the phenomenological theory of first-order structural phase transitions, with a special emphasis on reconstructive transformations in which a group-subgroup relationship between the symmetries of the phases is absent. It starts with a unified presentation of the current approach to first-order phase transitions, using the more recent results of the Landau theory of phase transitions and of the theory of singularities. A general theory of reconstructive phase transitions is then formulated, in which the structures surrounding a transition are expressed in terms of density-waves, providing a natural definition of the transition order-parameters, and a description of the corresponding phase diagrams and relevant physical properties. The applicability of the theory is illustrated by a large number of concrete examples pertaining to the various classes of reconstructive transitions: allotropic transformations of the elements, displacive and order-disorder transformations in metals, alloys and related structures, crystal-quasicrystal transformations.
Author: Arnaud Desmedt
Publisher:
ISBN:
Category :
Languages : fr
Pages : 234
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Book Description
DANS LES CRISTAUX ORGANIQUES D'INTERCROISSANCE DE LA THIOUREE (AUSSI APPELES COMPOSES D'INCLUSION), LES MOLECULES DE THIOUREE LIEES ENTRE ELLES PAR DES LIAISONS HYDROGENE, CONSTITUENT UNE SOUS-STRUCTURE HOTE SOUS FORME DE CANAUX LINEAIRES ET INFINIS DANS LESQUELS DES MOLECULES INVITEES DE TAILLE ADAPTEE PEUVENT S'INSERER. LE BUT DE CE TRAVAIL ETAIT D'ELUCIDER LES MECANISMES DE TRANSITION DE PHASE DE CES MATERIAUX COMPOSITES COMMENSURABLES EN ANALYSANT L'EVOLUTION THERMIQUE DES PROPRIETES DYNAMIQUES ET STRUCTURALES DU SYSTEME PROTOTYPE CYCLOHEXANE/THIOUREE. LA METHODOLOGIE ADOPTEE DANS CE TRAVAIL EST BASEE SUR UNE APPROCHE MULTI-TECHNIQUE. LES PROPRIETES DE SYMETRIE DES TROIS PHASES THERMOTROPIQUES DISTINGUEES PAR DES ANALYSES CALORIMETRIQUES DU COMPOSE D'INCLUSION ONT ETE SONDEES PAR DIFFRACTION DES RAYONS X ET DIFFUSION RAMAN. L'AFFINEMENT RIETVELD DE LA STRUCTURE CRISTALLINE A TEMPERATURE AMBIANTE A PERMIS DE REALISER DES SIMULATIONS NUMERIQUES DE LA DYNAMIQUE MOLECULAIRE ET CES RESULTATS ONT GUIDE L'INTERPRETATION DES SPECTRES EXPERIMENTAUX OBTENUS SUR MONOCRISTAL PAR DIFFUSION INCOHERENTE QUASI-ELASTIQUE DES NEUTRONS (IQNS) ET RMN DU DEUTERIUM. GRACE A LA LARGE FENETRE TEMPORELLE OFFERTE PAR LES SPECTROMETRES TEMPS DE VOL ET A RETRODIFFUSION EN IQNS ET A LA DETERMINATION PRECISE DES ORIENTATIONS MOLECULAIRE OFFERTE PAR LA RMN DU DEUTERIUM, LA DYNAMIQUE DES MOLECULES DE CYCLOHEXANE A ETE SONDEE DANS LES TROIS PHASES THERMOSTRUCTURALES DU COMPOSE. L'ENSEMBLE DE CES RESULTATS EXPERIMENTAUX A PERMIS DE PROPOSER DES MECANISMES DE MISE EN ORDRE DES MOLECULES INVITEES DANS LES TROIS PHASES CRISTALLINES, D'IDENTIFIER LES PARAMETRES D'ORDRE GOUVERNANT LES TRANSITIONS DE PHASE ET, EN SE BASANT SUR LA THEORIE DES GROUPES ET LA
Author:
Publisher: Elsevier
ISBN: 0444598316
Category : Science
Languages : en
Pages : 417
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Book Description
Modern Problems in Condensed Matter Sciences, Volume 14.2: Incommensurate Phases in Dielectrics, 2: Materials offers a physical picture of incommensurate insulators and gives readers an idea how experimental techniques can be used to study the dynamic and static properties of incommensurate systems on a microscopic level. The selection first offers information on the modulated phases in thiourea and incommensurate phase of quartz and barium sodium niobate (BSN). Discussions focus on the characteristics of the incommensurate phase in BSN, thermal hysteresis and relaxation effects, macroscopic symmetry breaking and related anomalies, properties of quartz and the discovery of the incommensurate phase, and dynamical properties. The text examines the incommensurate phases in an aromatic molecular crystal, including symmetry properties, molecular nature of the structural instability, satellite reflections, and excitations in incommensurate phases. The publication ponders on the incommensurate structures in liquid crystals, as well as liquid crystals and effects of incommensurability; incommensurate structures in cholesterol and sematic liquid crystals induced by external fields; incommensurate flex electric structure in hematic liquid crystals; and incommensurate sematic structures as polymorphous modifications. The selection is a vital reference for researchers interested in the incommensurate phases in dielectrics.
Author: JACQUES.. OLLIVIER
Publisher:
ISBN:
Category :
Languages : fr
Pages : 200
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Book Description
LES CRISTAUX ORGANIQUES PEUVENT PRESENTER DEUX FORMES D'INCOMMENSURABILITE. CERTAINS CRISTAUX PRESENTENT UNE PHASE INCOMMENSURABLE MODULEE A LA SUITE D'UNE TRANSITION DE PHASE STRUCTURALE. D'AUTRES SONT CONSTITUES DE PLUSIEURS SOUS-RESEAUX IMBRIQUES DONT LES PARAMETRES DE MAILLE RESPECTIFS SONT IRRATIONNELS ENTRE EUX. CE TRAVAIL A PORTE SUR L'ETUDE PAR DIFFUSION DE NEUTRONS DU 4,4'-DICHLORODIPHENYL SULFONE (BCPS) APPARTENANT A LA PREMIERE CATEGORIE DE COMPOSES INCOMMENSURABLES ET SUR L'ETUDE PAR DIFFUSION DE LA LUMIERE DE COMPOSES D'INCLUSION D'ALCANE/UREE APPARTENANT EUX A LA SECONDE CATEGORIE. L'ETUDE DU BCPS A MONTRE POUR LA PREMIERE FOIS DANS UNE PHASE INCOMMENSURABLE UN BLOCAGE DE LA FREQUENCE DU MODE MOU PILOTANT LA TRANSITION DISPLACIVE A UNE VALEUR FINIE A LA TRANSITION. SIMULTANEMENT UNE COMPOSANTE NON RESOLUE EN ENERGIE A FREQUENCE NULLE (PIC CENTRAL) EST APPARU SUR LES SPECTRES. LE MEME BLOCAGE DE FREQUENCE OBSERVE SUR LE MODE MOU A LA TRANSITION A ETE RETROUVE POUR LE PHASON, MODE CARACTERISTIQUE DE LA PHASE INCOMMENSURABLE. L'ETUDE DES COMPOSES D'INCLUSION D'ALCANE/UREE A MONTRE L'EXISTENCE DE DEUX CONTRIBUTIONS QUASIELASTIQUES DANS UNE REGION DU SPECTRE INEXPLOREE A CE JOUR. UNE DE CES CONTRIBUTIONS PEUT ETRE ATTRIBUEE AUX REORIENTATIONS DIFFUSIONNELLES DES MOLECULES D'ALCANE INCLUSES, ALORS QUE L'AUTRE PEUT ETRE RAISONNABLEMENT ATTRIBUEE AU MODE DE GLISSEMENT, EQUIVALENT DU PHASON POUR LES INCOMMENSURABLES COMPOSITES.
Author: ABDELKRIM.. MOULEHIAWY
Publisher:
ISBN:
Category :
Languages : fr
Pages : 236
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Book Description
DESCRIPTION DES DIFFERENTES PARTIES DU DISPOSITIF EXPERIMENTAL: SPECTROMETRE IR, CRYOSTAT OPTIQUE A REGULATION DE TEMPERATURE ET GROUPE DE POMPAGE. EXPOSE DE LA THEORIE DE L'EXCITON VIBRATIONNEL POUR CARACTERISER LES NIVEAUX D'ENERGIE EXCITONIQUES DU CRISTAL MOLECULAIRE. APPLICATION AU CYCLOHEXANE ET AU FERROCENE. INTERPRETATION DU PHENOMENE DE CHANGEMENT DE PHASE BASEE SUR LE TRANSFERT RESONNANT DE L'EXCITATION VIBRATIONNELLE
Author: Boris K. Vainshtein
Publisher: Springer Science & Business Media
ISBN: 3642975127
Category : Science
Languages : en
Pages : 538
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Book Description
Modern Crystallography provides an encyclopedic exposition of the field in four volumes written by Russian scientists. Structures of Crystals considers the ideal and real atomic structure of crystals as well as their electronic structures, the fundamentals of chemical bonding between atoms, geometric representations in the theory of crystal structure and crystal chemistry, as well as lattice energy. The important classes of crystal structures in inorganic compounds as well as structure polymers, liquid crystals, biological crystals, and macromolecules are treated. This second edition is complemented by recent data on many types of crystal structures - fullerenes, high-temperature superconductors, minerals, liquid crystals, etc.
Author: Y Sok Khay Chhor (auteur d'une thèse de sciences.)
Publisher:
ISBN:
Category :
Languages : fr
Pages : 304
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Book Description
