Y. Gagou, B. Allouche, P. Saint-Grégoire, M. El Marssi
Resistive Random-Access Memories (ReRAM) are an alternative way to create new memory devices. This is physically possible due to the existence in the material, of two resistive states clearly discreditable, as a function of voltage value and polarity first parameter under control to pass from one state to another one. However, the mechanism of the resistance switching is not simple and is under debate. We present in the present chapter all the factors entering in the switching process in tetragonal tungsten bronze (TTB) type structure oxide thin films deposited by PLD technique onto MgO or STO substrates. Results show that GdK2Nb5O15 (GKN) thin films deposited on MgO and STO substrates are resistively switchable. It was found that the nature of the substrate strongly affects the resistance ratio: GKN on SRO/LSCO/MgO showed a large hysteresis compared to GKN on SRO/STO. Substrate effect and oxygen vacancy on resistance switching in GKN thin film were studied in the same experimental conditions. The study of resistance switching in the GKN/MgO and GKN/STO thin films has confirmed that for low voltages, below the threshold value of 1.3 V, the electric transport is dominated by the formation of a Schottky type barrier, which allows a minimum leakage current. Resistance switching in GKN is attributed to the oxygen vacancies migration which can be controlled by the substrate or the frequency sweep.
{"title":"Resistance Switching Effect in Octahedral framework oxide","authors":"Y. Gagou, B. Allouche, P. Saint-Grégoire, M. El Marssi","doi":"10.23647/ca.md20200109","DOIUrl":"https://doi.org/10.23647/ca.md20200109","url":null,"abstract":"Resistive Random-Access Memories (ReRAM) are an alternative way to create new memory devices. This is physically possible due to the existence in the material, of two resistive states clearly discreditable, as a function of voltage value and polarity first parameter under control to pass from one state to another one. However, the mechanism of the resistance switching is not simple and is under debate. We present in the present chapter all the factors entering in the switching process in tetragonal tungsten bronze (TTB) type structure oxide thin films deposited by PLD technique onto MgO or STO substrates. Results show that GdK2Nb5O15 (GKN) thin films deposited on MgO and STO substrates are resistively switchable. It was found that the nature of the substrate strongly affects the resistance ratio: GKN on SRO/LSCO/MgO showed a large hysteresis compared to GKN on SRO/STO. Substrate effect and oxygen vacancy on resistance switching in GKN thin film were studied in the same experimental conditions. The study of resistance switching in the GKN/MgO and GKN/STO thin films has confirmed that for low voltages, below the threshold value of 1.3 V, the electric transport is dominated by the formation of a Schottky type barrier, which allows a minimum leakage current. Resistance switching in GKN is attributed to the oxygen vacancies migration which can be controlled by the substrate or the frequency sweep.","PeriodicalId":19388,"journal":{"name":"OAJ Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83546127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Vtyurin, A. Krylov, S. Krylova, Y. Gerasimova, A. A. Ivanenko, V. Voronov
Phase transitions in crystals of fluorine-containing elpasolites are investigated by Raman scattering spectroscopy. It was found that lattice instabilities in these crystals are induced by soft mode condensations, while restorations of these modes in the distorted phases have not been observed due to their strong interactions with low-frequency noncritical lattice vibrations. Increasing the mass of a rare-earth ions shifts down frequencies of noncritical modes, that enhances these interactions and leads to a narrowing of the range of existence of intermediate phase and then to its disappearance.
{"title":"Temperature phase transitions in Rb2KRe3+F6 elpasolites - Raman spectroscopy study","authors":"A. Vtyurin, A. Krylov, S. Krylova, Y. Gerasimova, A. A. Ivanenko, V. Voronov","doi":"10.23647/ca.md20202508","DOIUrl":"https://doi.org/10.23647/ca.md20202508","url":null,"abstract":"Phase transitions in crystals of fluorine-containing elpasolites are investigated by Raman scattering spectroscopy. It was found that lattice instabilities in these crystals are induced by soft mode condensations, while restorations of these modes in the distorted phases have not been observed due to their strong interactions with low-frequency noncritical lattice vibrations. Increasing the mass of a rare-earth ions shifts down frequencies of noncritical modes, that enhances these interactions and leads to a narrowing of the range of existence of intermediate phase and then to its disappearance.","PeriodicalId":19388,"journal":{"name":"OAJ Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82450116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hybrid lead halide perovskites emerged at the beginning of 2010s decade as one of the most promising materials for photovoltaic applications. Easy and low-cost solution-based fabrication processes can be used, obtaining perovskite solar cells (PSCs) with efficiencies above 20%. However, there still are some major issues to overcome, like stabiliddty, and the general understanding of the recombination mechanisms resHybrid lead halide perovskites emerged at the beginning of 2010s decade as one of the most promising materials for photovoltaic applications. Easy and low-cost solution-based fabrication processes can be used, obtaining perovskite solar cells (PSCs) with efficiencies above 20%. However, there still are some major issues to overcome, like stability, and the general understanding of the recombination mechanisms results particularly puzzling. In this chapter, an analysis is provided on most recent research results about the different mechanisms, location and relationships of charge carrier recombination in PSCs. After introducing the theoretical framework, including the main transport equations and relations with luminescence techniques, the radiative and non-radiative natures of recombination are commented and compared in terms of main contributions. Also, the effects of changing the perovskite composition and morphology are surveyed. The location of the recombination processes, whether in the bulk material or towards the interface, are tackled, as well as related features with the current-voltage hysteresis. On the latter, and along the complete chapter, the dual ionic-electronic conductivity of hybrid lead halide perovskites is particularly attended. ults particularly puzzling. In this chapter, an analysis is provided on most recent research results about the different mechanisms, location and relationships of charge carrier recombination in PSCs. After introducing the theoretical framework, including the main transport equations and relations with luminescence techniques, the radiative and non-radiative natures of recombination are commented and compared in terms of main contributions. Also, the effects of changing the perovskite composition and morphology are surveyed. The location of the recombination processes, whether in the bulk material or towards the interface, are tackled, as well as related features with the current-voltage hysteresis. On the latter, and along the complete chapter, the dual ionic-electronic conductivity of hybrid lead halide perovskites is particularly attended. ybrid lead halide perovskites emerged at the beginning of 2010s decade as one of the most promising materials for photovoltaic applications. Easy and low-cost solution-based fabrication processes can be used, obtaining perovskite solar cells (PSCs) with efficiencies above 20%. However, there still are some major issues to overcome, like stability, and the general understanding of the recombination mechanisms results particularly puzzling. In this chap
{"title":"Hybrid perovskites: Charge carrier recombination effects in photovoltaic devices","authors":"O. Amora","doi":"10.23647/ca.md20201601","DOIUrl":"https://doi.org/10.23647/ca.md20201601","url":null,"abstract":"Hybrid lead halide perovskites emerged at the beginning of 2010s decade as one of the most promising materials for photovoltaic applications. Easy and low-cost solution-based fabrication processes can be used, obtaining perovskite solar cells (PSCs) with efficiencies above 20%. However, there still are some major issues to overcome, like stabiliddty, and the general understanding of the recombination mechanisms resHybrid lead halide perovskites emerged at the beginning of 2010s decade as one of the most promising materials for photovoltaic applications. Easy and low-cost solution-based fabrication processes can be used, obtaining perovskite solar cells (PSCs) with efficiencies above 20%. However, there still are some major issues to overcome, like stability, and the general understanding of the recombination mechanisms results particularly puzzling. In this chapter, an analysis is provided on most recent research results about the different mechanisms, location and relationships of charge carrier recombination in PSCs. After introducing the theoretical framework, including the main transport equations and relations with luminescence techniques, the radiative and non-radiative natures of recombination are commented and compared in terms of main contributions. Also, the effects of changing the perovskite composition and morphology are surveyed. The location of the recombination processes, whether in the bulk material or towards the interface, are tackled, as well as related features with the current-voltage hysteresis. On the latter, and along the complete chapter, the dual ionic-electronic conductivity of hybrid lead halide perovskites is particularly attended. ults particularly puzzling. In this chapter, an analysis is provided on most recent research results about the different mechanisms, location and relationships of charge carrier recombination in PSCs. After introducing the theoretical framework, including the main transport equations and relations with luminescence techniques, the radiative and non-radiative natures of recombination are commented and compared in terms of main contributions. Also, the effects of changing the perovskite composition and morphology are surveyed. The location of the recombination processes, whether in the bulk material or towards the interface, are tackled, as well as related features with the current-voltage hysteresis. On the latter, and along the complete chapter, the dual ionic-electronic conductivity of hybrid lead halide perovskites is particularly attended. ybrid lead halide perovskites emerged at the beginning of 2010s decade as one of the most promising materials for photovoltaic applications. Easy and low-cost solution-based fabrication processes can be used, obtaining perovskite solar cells (PSCs) with efficiencies above 20%. However, there still are some major issues to overcome, like stability, and the general understanding of the recombination mechanisms results particularly puzzling. In this chap","PeriodicalId":19388,"journal":{"name":"OAJ Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90823954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nanometric laminar two-dimensional artificial multiferroic oxide thin films can be elaborated using spinel ferrites and perovskite ferroelectrics like CoFe2O4 and BaTiO3. Such materials can retain their individual ferromagnetic or ferroelectric properties. In the thin epitaxial film regime a cross coupling of these properties is possible thanks to strain engineering. After introducing the concepts supporting artificial multiferroic laminar structures, the growth of strained BaTiO3 thin films and the growth of subsequent Co-ferrites layers will be detailed. With respect to the relative film thickness, a detailed understanding of the elastic behavior of these films will be proposed based on the characterization using several synchrotron radiation techniques including x-ray specular and off-specular diffraction, x-ray absorption spectroscopy, as well as x-ray magnetic circular dichroism.
{"title":"Artificial laminar oxide multiferroic magnetoelectric thin film structures - Elaboration methods and study by synchrotron radiation techniques","authors":"C. Mocuta, P. Ohresser, A. Barbier","doi":"10.23647/ca.md20202604","DOIUrl":"https://doi.org/10.23647/ca.md20202604","url":null,"abstract":"Nanometric laminar two-dimensional artificial multiferroic oxide thin films can be elaborated using spinel ferrites and perovskite ferroelectrics like CoFe2O4 and BaTiO3. Such materials can retain their individual ferromagnetic or ferroelectric properties. In the thin epitaxial film regime a cross coupling of these properties is possible thanks to strain engineering. After introducing the concepts supporting artificial multiferroic laminar structures, the growth of strained BaTiO3 thin films and the growth of subsequent Co-ferrites layers will be detailed. With respect to the relative film thickness, a detailed understanding of the elastic behavior of these films will be proposed based on the characterization using several synchrotron radiation techniques including x-ray specular and off-specular diffraction, x-ray absorption spectroscopy, as well as x-ray magnetic circular dichroism.","PeriodicalId":19388,"journal":{"name":"OAJ Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87636840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. H. Michels-Brito, L. Michels, K. Hunvik, É. C. dos Santos, B. Pacakova, L. Cavalcanti, K. Knudsen, H. Bordallo, O. Fossum
Fluorohectorite is a synthetic 2:1 layer smectite clay where the presence of exchangeable cations located between water molecules in the interlayer space allows for expansion of the crystal lattice. This swelling property is extremely relevant to many applications including water treatment, bioactive molecules intercalation (drug delivery), soil remediation, CO2capture as well as extra-terrestrial environment studies. In the present chapter, the aim is to discuss why Fluorohectorite can be in particular advantageous for many applications where retention of big volumes is an issue. We will also discuss on the main experimental techniques used to study these materials.
{"title":"Experimental methods to study clay minerals and perspective applications of Fluorohectorite","authors":"P. H. Michels-Brito, L. Michels, K. Hunvik, É. C. dos Santos, B. Pacakova, L. Cavalcanti, K. Knudsen, H. Bordallo, O. Fossum","doi":"10.23647/ca.md20201501","DOIUrl":"https://doi.org/10.23647/ca.md20201501","url":null,"abstract":"Fluorohectorite is a synthetic 2:1 layer smectite clay where the presence of exchangeable cations located between water molecules in the interlayer space allows for expansion of the crystal lattice. This swelling property is extremely relevant to many applications including water treatment, bioactive molecules intercalation (drug delivery), soil remediation, CO2capture as well as extra-terrestrial environment studies. In the present chapter, the aim is to discuss why Fluorohectorite can be in particular advantageous for many applications where retention of big volumes is an issue. We will also discuss on the main experimental techniques used to study these materials.","PeriodicalId":19388,"journal":{"name":"OAJ Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80175395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recently, the one-dimensional ferroelectric perovskite nanostructures have been of high interest due to a number of unique properties that allow the improvement of the current ceramic nanotechnologies. In order to receive the nanoparticles of a given structure and morphology it is quite important to expand and summary the knowledge regarding the physicochemical processes of the formation and growth of a new phase. Therefore, in this paper, based on the existing works, an attempt to describe the influence of the crystallization mechanism as well as hydrothermal synthesis parameters (such as the reagent nature, pH, concentration, surfactant, heat treatment mode) on the peculiarities of the anisotropic growth and the formation of the one-dimensional perovskite nanostructures was carried out.
{"title":"A review of the synthesis of single-crystal 1D perovskite nanostructures by the hydrothermal method","authors":"O. Kovalenko, A. Ragulya","doi":"10.23647/ca.md20200307","DOIUrl":"https://doi.org/10.23647/ca.md20200307","url":null,"abstract":"Recently, the one-dimensional ferroelectric perovskite nanostructures have been of high interest due to a number of unique properties that allow the improvement of the current ceramic nanotechnologies. In order to receive the nanoparticles of a given structure and morphology it is quite important to expand and summary the knowledge regarding the physicochemical processes of the formation and growth of a new phase. Therefore, in this paper, based on the existing works, an attempt to describe the influence of the crystallization mechanism as well as hydrothermal synthesis parameters (such as the reagent nature, pH, concentration, surfactant, heat treatment mode) on the peculiarities of the anisotropic growth and the formation of the one-dimensional perovskite nanostructures was carried out.","PeriodicalId":19388,"journal":{"name":"OAJ Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88070632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Ivanchenko, S. Umerova, D. Baranovskyi, O. Kovalenko, A. Ragulya
The diversity of the applicational scope of modern printed electronics relentlessly requires the improvement of operational properties simultaneously with reducing the overall dimensions of devices. One of the most effective ways to overcome this major obstacle is the reduction of functional layers thickness in respect to the size of the device. In the present article, we are discussing a simple way of practical implementation of miniaturization concept through the application of a well-known high-productive industrial method of tape casting for obtaining thin nanostructured ceramic layers based on BaTiO3 nanopowders for MLCC. Using of nanosized powders per se imply a new approach of developing suspensions with suitable rheology for tape casting. We demonstrate, that a length of polymer molecule defines the size of floccules and therefore influences the thickness and surface quality of tape casted films. A certain nanopowder/polymer ratio contributes to the formation of the tapes with the surface roughness comparable with the size of one nanoparticle (20-25 nm). Moreover, it was established that developed suspensions are extremely sensitive to temperature changes. Lowering the temperature significantly affects the flow character of suspension and thus the thickness of casted tapes. Considering this fact, we propose an effective self-developed pre-cooling method of nanopowder suspension casting, which allows obtaining extremely thin and smooth tapes with a thickness of less than 1 µm and surface roughness of 20–25 nm by tape casting method.
{"title":"BaTiO3 films for multilayer devices by tape casting","authors":"S. Ivanchenko, S. Umerova, D. Baranovskyi, O. Kovalenko, A. Ragulya","doi":"10.23647/ca.md20201707","DOIUrl":"https://doi.org/10.23647/ca.md20201707","url":null,"abstract":"The diversity of the applicational scope of modern printed electronics relentlessly requires the improvement of operational properties simultaneously with reducing the overall dimensions of devices. One of the most effective ways to overcome this major obstacle is the reduction of functional layers thickness in respect to the size of the device. In the present article, we are discussing a simple way of practical implementation of miniaturization concept through the application of a well-known high-productive industrial method of tape casting for obtaining thin nanostructured ceramic layers based on BaTiO3 nanopowders for MLCC. Using of nanosized powders per se imply a new approach of developing suspensions with suitable rheology for tape casting. We demonstrate, that a length of polymer molecule defines the size of floccules and therefore influences the thickness and surface quality of tape casted films. A certain nanopowder/polymer ratio contributes to the formation of the tapes with the surface roughness comparable with the size of one nanoparticle (20-25 nm). Moreover, it was established that developed suspensions are extremely sensitive to temperature changes. Lowering the temperature significantly affects the flow character of suspension and thus the thickness of casted tapes. Considering this fact, we propose an effective self-developed pre-cooling method of nanopowder suspension casting, which allows obtaining extremely thin and smooth tapes with a thickness of less than 1 µm and surface roughness of 20–25 nm by tape casting method.","PeriodicalId":19388,"journal":{"name":"OAJ Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86509850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article reviews Framework Structures (FWSs), defined as crystalline materials built of rigid AXn polyhedra sharing vertices (like perovskites, tungsten bronzes, Dion-Jacobson, Ruddlesden-Popper, and Aurivillius phases, quartz, silicates, and others), and their pecularities resulting from this linkage. The situation of rigid units linked by common vertices may allow the units to accomplish concordant rotations without deformation, which gives rise to soft phonon modes called “Rigid Unit Modes” (RUMs). The condensation of a RUM can trigger structural phase transitions to a structure of lower symmetry, with tilted polyhedra, at the origin of spontaneous ferroic or multiferroic properties. We overview results precedently obtained on RUMs in perovskites, tetragonal tungsten bronzes, and quartz, and detail new results on “maximally localized RUMs” (MLRUMs), a fundamental new concept in the physics of RUMs. We introduce also the related new concept of “skeletions” that allows to generate all ferroelastic phases found in these systems, and generalizes the Glazer's tilt-system approach.
{"title":"Framework structure crystalline materials and Rigid Unit Modes (RUMs). Introducing the new concept of MLRUMs and skeletions Authors","authors":"M. Smirnov, P. Saint-Grégoire","doi":"10.23647/ca.md20202005","DOIUrl":"https://doi.org/10.23647/ca.md20202005","url":null,"abstract":"This article reviews Framework Structures (FWSs), defined as crystalline materials built of rigid AXn polyhedra sharing vertices (like perovskites, tungsten bronzes, Dion-Jacobson, Ruddlesden-Popper, and Aurivillius phases, quartz, silicates, and others), and their pecularities resulting from this linkage. The situation of rigid units linked by common vertices may allow the units to accomplish concordant rotations without deformation, which gives rise to soft phonon modes called “Rigid Unit Modes” (RUMs). The condensation of a RUM can trigger structural phase transitions to a structure of lower symmetry, with tilted polyhedra, at the origin of spontaneous ferroic or multiferroic properties. We overview results precedently obtained on RUMs in perovskites, tetragonal tungsten bronzes, and quartz, and detail new results on “maximally localized RUMs” (MLRUMs), a fundamental new concept in the physics of RUMs. We introduce also the related new concept of “skeletions” that allows to generate all ferroelastic phases found in these systems, and generalizes the Glazer's tilt-system approach.","PeriodicalId":19388,"journal":{"name":"OAJ Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82575911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We will address in detail the structural distortions responsible for the symmetry lowering of the ideal cubic Pm-3m perovskite to the orthorhombic Pnma structure of RFeO3 and RMnO3 (R = trivalent rare-earth cation), important to the stabilization of the different magnetic and multiferroic phases in these materials. We will also show how the Amplimodes tool of Bilbao Crystallographic Server is useful in quantifying these distortions and establish which phonons can be used as probes of both the octahedra tilting and deformation.
{"title":"Structural distortions of orthorhombic RFeO3 and RMnO3","authors":"R. Vilarinho, A. Almeida, J. Agostinho Moreira","doi":"10.23647/ca.md20202608","DOIUrl":"https://doi.org/10.23647/ca.md20202608","url":null,"abstract":"We will address in detail the structural distortions responsible for the symmetry lowering of the ideal cubic Pm-3m perovskite to the orthorhombic Pnma structure of RFeO3 and RMnO3 (R = trivalent rare-earth cation), important to the stabilization of the different magnetic and multiferroic phases in these materials. We will also show how the Amplimodes tool of Bilbao Crystallographic Server is useful in quantifying these distortions and establish which phonons can be used as probes of both the octahedra tilting and deformation.","PeriodicalId":19388,"journal":{"name":"OAJ Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84571928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The lattice dynamics of perovskite oxides are investigated theoretically within the polarizability model which is a nonlinear approach taking into account anharmonic electron-lattice interactions. The emphasis is on local lattice anomalies which appear in the phonon modes dispersion. Above the actual phase transition temperature finite size polarized clusters appear at an onset temperature TBH which marks the precursor formation temperature. These local anomalies appear as well experimentally and are reviewed for various perovskite compounds.
{"title":"The intricate lattice dynamics of perovskite oxides","authors":"A. Bussmann-Holder, J. Ko, K. Roleder","doi":"10.23647/ca.md20202805","DOIUrl":"https://doi.org/10.23647/ca.md20202805","url":null,"abstract":"The lattice dynamics of perovskite oxides are investigated theoretically within the polarizability model which is a nonlinear approach taking into account anharmonic electron-lattice interactions. The emphasis is on local lattice anomalies which appear in the phonon modes dispersion. Above the actual phase transition temperature finite size polarized clusters appear at an onset temperature TBH which marks the precursor formation temperature. These local anomalies appear as well experimentally and are reviewed for various perovskite compounds.","PeriodicalId":19388,"journal":{"name":"OAJ Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83704177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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