Structural and Magnetic Phase Transitions in Hexagonal Perovskites PDF Download
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Author: Iram Munawar
Publisher:
ISBN:
Category : Mineralogy
Languages : en
Pages : 0
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Author: Iram Munawar
Publisher:
ISBN:
Category : Mineralogy
Languages : en
Pages : 0
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Author: Aleksandra Podolska-Strycharska
Publisher:
ISBN:
Category :
Languages : en
Pages : 17
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Author: Karl A. Mller
Publisher: World Scientific
ISBN: 9814317691
Category : Science
Languages : en
Pages : 583
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Book Description
In this book some 50 papers published by K A Mller as author or co-author over several decades, amplified by more recent work mainly by T W Kool with collaborators, are reproduced. The main subject is Electron Paramagnetic Resonance (EPR) applied to the study of perovskites and other oxides with related subjects. This wealth of papers is organized into eleven chapters, each with an introductory text written in the light of current understanding. The contributions of the first editor on structural phase transitions have been immense, and because K A Mller and J C Fayet have published a review paper on the subject, the latter is reproduced in chapter VII. Not related to EPR is a part of chapter VIII on the dipolar and quantum paraelectric behavior with dielectric studies. in chapter X two papers proving the existence of Fermi glasses are reproduced. The year 1986 bears some significance: early in this year the paper by Bednorz and Mller on the possible observation of superconductivity was published. This resulted in a substantial shift in the paradigm of condensed matter physics, to which the present first editor has contributed scientifically with others and which will be reviewed in a second volume.
Author: Pierre Villars
Publisher: Walter de Gruyter
ISBN: 3110276658
Category : Science
Languages : en
Pages : 1827
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Book Description
By browsing about 10 000 000 scientific articles of over 200 major journals mainly in a 'cover to cover approach' some 200 000 publications were selected. The extracted data is part of the following fundamental material research fields: crystal structures (S), phase diagrams (also called constitution) (C) and the comprehensive field of intrinsic physical properties (P). This work has been done systematically starting with the literature going back to 1900. The above mentioned research field codes (S, C, P) as well as the chemical systems investigated in each publication were included in the present work. The aim of the Inorganic Substances Bibliography is to provide researchers with a comprehensive compilation of all up to now published scientific publications on inorganic systems in only three handy volumes.
Author: Graham Missell King
Publisher:
ISBN:
Category :
Languages : en
Pages : 148
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Abstract: This work describes the synthesis and characterization of a number of new AA'BB'O6 perovskites which possess the unusual combination of rock salt ordering of B/B' and layered ordering of A/A'. These compounds have been structurally characterized by powder X-ray and neutron diffraction as well as transmission electron microscopy. Several of these compounds are found to adopt polar P21 space group symmetry as a result of the cation ordering in combination with a-a-c+ octahedral tilting. A number of other compounds are shown to have a compositional modulation of the A-site cations that is accompanied by a twinning of the octahedral tilt system. Using UV-Vis spectroscopy the band gaps of these compounds have been determined. This analysis shows that NaLnMgWO6 compounds are insulators while NaLnMnWO6 compounds are semiconductors. The dielectric constants are found to be in the range of approximately 20-35. The magnetic properties of the NaLnMnWO6 and NaLnMgWO6 compounds have been measured. All NaLnMnWO6 compounds are found to order antiferromagnetically at temperatures ranging from 6-15 K. The NaLnMgWO6 compounds do not show any indications of magnetic order. The magnetic structures of NaLaMnWO6, NaNdMnWO6, and NaTbMnWO6 have been determined from neutron powder diffraction. NaLaMnWO6 is found to order into a simple commensurate structure. NaNdMnWO6 orders incommensurately due to interactions between the two magnetic ions. NaTbMnWO6 is found to pass through two magnetic phase transitions. Just below its Néel temperature it has an incommensurate modulation of its structure which disappears as it is further cooled.
Author: Francis S. Galasso
Publisher: Elsevier
ISBN: 1483146022
Category : Science
Languages : en
Pages : 228
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Book Description
Structure, Properties and Preparation of Perovskite-Type Compounds, Volume 5 presents the various methods of preparing powders, single crystals, and thin films of perovskite-type compounds. This book discusses the structure of perovskite-type compounds and their properties. Organized into 11 chapters, this volume begins with an overview of the structure, properties, and preparation of perovskite-type compounds. This text then examines how X-ray diffraction can be used to determine unit cell data and to orient single crystals. Other chapters consider the effect of nuclear radiation on the properties of ferroelectric materials. This book discusses as well the phase transitions in perovskite-type compounds, which are often associated with a change in ferroelectric properties. The final chapter explores the two techniques in the preparation of the ternary carbides with the perovskite structure, which involves melting the appropriate proportions of the two metals and carbon under argon. This book is a valuable resource for solid-state chemists.
Author: Ilyas Qasim
Publisher:
ISBN:
Category : Oxides
Languages : en
Pages :
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Author: Asish K Kundu
Publisher: Springer
ISBN: 8132227611
Category : Technology & Engineering
Languages : en
Pages : 174
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Book Description
Magnetic perovskite with multi functional properties (magneto-resistive, magneto-dielectric, multiferroics, spintronics, etc.) have attracted increasing attention due to their possible applications towards storage materials and intriguing fundamental Physics. Despite the numerous investigations on multi functional materials in the past few years, a very few magnetic perovskites have been known to realize as ferromagnetic-insulators. In perovskites centred transition metal oxides strong interplay between lattice, charge, spin and/or orbital degrees of freedom provide a fantastic playground to tune their physical properties. The main purpose of this book is to introduce the phenomenon and physics of complex magnetism (phase separation, spin glass, frustrations, etc.) in perovskite manganites and cobaltites via an experimental approach. The book is organized into four chapters; Chap. 1 gives a brief introduction of various interesting phenomena in magnetic perovskites. Chapter 2 describes the results of the investigations on electronic phase separation and glassy ferromagnetism of the hole-doped perovskite manganites and cobaltites. Ordered and disordered effects and related aspects in hole-doped perovskite cobaltites are described in Chap. 3. Finally, in Chap. 4 the bismuth based magnetic perovskite is discussed.
Author: Daniel K. Jackson
Publisher:
ISBN: 9781303478888
Category :
Languages : en
Pages : 129
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Book Description
This thesis studies static and dynamic optical effects through the phase transitions of two perovskite materials, potassium tantalate niobate (KTN) and sodium bismuth titanate (NBT). Multiple experimental techniques are utilized to more thoroughly understand the nature of the phase transitions and determine the various contributions to the transitions. In the first part, the temperature dependence of the birefringence of three different potassium tantalate niobate, or KTN, crystals is examined upon approaching the phase transition from cubic to tetragonal. This birefringence, which is in violation of crystalline symmetry conditions, is caused by the strain originating from the difference in unit cell size of the end materials, KNbO3 and KTaO3. This strain is either a gradient or a modulation due to the growth striations in the material, and diffraction is observed from the volume phase gratings via the difference in refractive indices. Upon approaching the phase transition, the birefringence displays rapid temperature dependence due to the formation of polar nano-domains which are preferentially oriented due to interaction with the striations. The variation of the birefringence with temperature is reported and discussed in the context of the existing literature. A sample of K0.977Li0.003Ta0.845Nb0.155O3 or KLTN15.5 with well defined striations, KTa0.73Nb0.27O3or KTN27) with no well defined striations and a sample of KLTN36 doped with copper and vanadium and diffuse striations are examined with respect to their optical behaviors in the cubic paraelectric phase. In the second part, Raman spectroscopic measurements of sodium bismuth titanate (Na0.5Bi0.5TiO3 or NBT) were carried out upon cooling from 1000 K to 80 K to study its two phase transitions. Full spectral deconvolution was performed, comparing the results from several fitting models, with a particular emphasis on the evolution of the central peak and low frequency phonon modes. The central intensity profile is found to be composed of two well-defined Lorentzian peaks, the temperature dependence of which suggests the presence of fluctuations in M-point and R-point rotations of the oxygen octahedra as well as fluctuations in cation displacements related to polar nano-domains. The temperature behavior of both central peaks is discussed in relation to the (tilting or shifting) transition behavior in similar perovskite systems. The four observed low frequency phonon modes indicate a different symmetry assignment than the commonly assigned R3c for the low temperature phase.
Author: Rada Savkina
Publisher: CRC Press
ISBN: 100005439X
Category : Science
Languages : en
Pages : 317
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Book Description
Oxide-based materials and structures are becoming increasingly important in a wide range of practical fields including microelectronics, photonics, spintronics, power harvesting, and energy storage in addition to having environmental applications. This book provides readers with a review of the latest research and an overview of cutting-edge patents received in the field. It covers a wide range of materials, techniques, and approaches that will be of interest to both established and early-career scientists in nanoscience and nanotechnology, surface and material science, and bioscience and bioengineering in addition to graduate students in these areas. Features: Contains the latest research and developments in this exciting and emerging field Explores both the fundamentals and applications of the research Covers a wide range of materials, techniques, and approaches
