Special Issue "Crystallography of Functional Materials"

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Crystal Engineering".

Deadline for manuscript submissions: closed (20 March 2017)

Special Issue Editors

Guest Editor
Dr. Winnie Wong-Ng

Material Measurement Laboratory, The National Institute of Standards and Technology (NIST)
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Interests: Crystallography (laboratory and synchrotron X-ray and neutron diffraction), crystal chemistry, phase equilibria, structure/property relationships of functional materials; standard reference materials; reference X-ray powder patterns; databases; modeling; energy conversion materials; high-throughput combinatorial thin film approaches
Guest Editor
Dr. Claudia Rawn

Department of Materials Science and Engineering, University of Tennessee
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Interests: In situ neutron and X-ray powder diffraction; small molecule crystallography; ceramic synthesis; structure/property relations

Special Issue Information

Dear Colleagues,

In the new millennium, functional materials will play an increasingly vital role in economic growth and quality of life. These materials encompass areas in electronics, computers, information, communication, biotechnology, aerospace, defense, environment, energy, medicine, and consumer products. The development and fundamental understanding of the properties of functional materials are central to technological needs, and are at the forefront of materials research.

Functional materials, which possess specific natural properties and functions, form the basis for a wide range of technologies, as stated above. A partial list of these properties includes ferroelectricity, piezoelectricity, ferromagnetism, ionic conductivity, superconductivity, photovoltaic behavior, and giant magneto-resistance, with resulting applications in microelectronic devices and data storage, sensing, energy storage, hydrogen storage, thermoelectric waste heat conversion, solar cells, fuel cells, batteries, and other energy conversion and harvesting applications. Functional materials of interest cover different classes of solid-state materials ranging from semiconductors to polymers, from molecular crystals to nanoparticles.

The field of crystallography provides the foundation for the understanding of the structure properties relationship. It bridges the fundamental understanding of materials with the applications. As functional materials play a critical role in our modern society and future economic, physical, and social success, the underlying crystallographic information for these materials is of utmost importance for the many research communities involved.

The goal of this Special Issue is to solicit papers to cover the latest developments in the cross disciplinary fields of structure science and functional materials, so as to provide structure and property relationships including but not limited to phase transformations, local structures, modular and disordered structures, and defects. The forms of materials of interest include single crystals, bulk ceramics, amorphous solids, liquid crystals, thin films and nanostructures. In situ and in operando crystallography and high-pressure crystallography are also important areas for this issue. We welcome discussions of various techniques or combined techniques of investigation, including diffraction (X-ray (laboratory and synchrotron), neutron, and electron) and various scattering techniques.

Dr. Winnie Wong-Ng
Dr. Claudia Rawn
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Functional materials
  • Structure (including local structure) and property relationships
  • Single crystals, bulk ceramics, amorphous solids, liquid crystals, thin films and nanostructures
  • In situ and non-ambient crystallography
  • Diffraction and scattering techniques

Published Papers (9 papers)

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Editorial

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Open AccessEditorial Crystallography of Functional Materials
Crystals 2017, 7(9), 279; doi:10.3390/cryst7090279
Received: 13 September 2017 / Revised: 13 September 2017 / Accepted: 13 September 2017 / Published: 15 September 2017
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Abstract
The goal of this special issue is to obtain new insights into the roles of crystallography in functional materials. This special issue consists of eight papers illustrating the structure and property relationships, as well as applications of selected classes of materials that deal
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The goal of this special issue is to obtain new insights into the roles of crystallography in functional materials. This special issue consists of eight papers illustrating the structure and property relationships, as well as applications of selected classes of materials that deal with various aspects of functional materials, ranging from battery, magnetic, photocatalysis, and waveguide materials, to luminescent metal-organic frameworks and borates, semiconductors, and inorganic electrides. This issue provides further evidence of the importance of crystallography in understanding and improving various properties of functional materials, whether they are single crystals, bulk polycrystalline materials, or thin films. Full article
(This article belongs to the Special Issue Crystallography of Functional Materials)

Research

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Open AccessArticle Extended Defect Propagation in Highly Tensile-Strained Ge Waveguides
Crystals 2017, 7(6), 157; doi:10.3390/cryst7060157
Received: 8 March 2017 / Revised: 5 May 2017 / Accepted: 11 May 2017 / Published: 26 May 2017
Cited by 1 | PDF Full-text (7155 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Tensile-strained Ge is a possible laser material for Si integrated circuits, but reports of lasers using tensile Ge show high threshold current densities and short lifetimes. To study the origins of these shortcomings, Ge ridge waveguides with tensile strain in three dimensions were
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Tensile-strained Ge is a possible laser material for Si integrated circuits, but reports of lasers using tensile Ge show high threshold current densities and short lifetimes. To study the origins of these shortcomings, Ge ridge waveguides with tensile strain in three dimensions were fabricated using compressive silicon nitride (SiNx) films with up to 2 GPa stress as stress liners. A Raman peak shift of up to 11 cm−1 was observed, corresponding to 3.6% hydrostatic tensile strain for waveguides with a triangular cross-section. Real time degradation in tensile-strained Ge was observed and studied under transmission electron microscopy (TEM). A network of defects, resembling dark line defects, was observed to form and propagate with a speed and density strongly correlated with the local strain extracted from both modeled and measured strain profiles. This degradation suggests highly tensile-strained Ge lasers are likely to have significantly shorter lifetime than similar GaAs or InGaAs quantum well lasers. Full article
(This article belongs to the Special Issue Crystallography of Functional Materials)
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Open AccessArticle Crystallography and Growth of Epitaxial Oxide Films for Fundamental Studies of Cathode Materials Used in Advanced Li-Ion Batteries
Crystals 2017, 7(5), 127; doi:10.3390/cryst7050127
Received: 13 March 2017 / Revised: 25 April 2017 / Accepted: 28 April 2017 / Published: 8 May 2017
Cited by 2 | PDF Full-text (7796 KB) | HTML Full-text | XML Full-text
Abstract
Li-ion battery systems, synthesized as epitaxial thin films, can provide powerful insights into their electrochemical processes. Crystallographic analysis shows that many important cathode oxides have an underlying similarity: their structures can be considered as different ordering schemes of Li and transition metal ions
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Li-ion battery systems, synthesized as epitaxial thin films, can provide powerful insights into their electrochemical processes. Crystallographic analysis shows that many important cathode oxides have an underlying similarity: their structures can be considered as different ordering schemes of Li and transition metal ions within a pseudo-cubic sublattice of oxygen anions arranged in a face-center cubic (FCC) fashion. This oxygen sublattice is compatible with SrTiO3 and similar perovskite oxides, thus perovskites can be used as supporting substrates for growing epitaxial cathode films. The predicted epitaxial growth and crystallographic relations were experimentally verified for different oxide films deposited by pulsed laser deposition (PLD) on SrTiO3 or SrRuO3/SrTiO3 of different orientations. The results based on cross-sectional high-resolution TEM of the following films are presented in the paper: (a) trigonal LiCoO2; (b) orthorhombic LiMnO2; (c) monoclinic Li2MnO3; (d) compositionally-complex monoclinic Li1.2Mn0.55Ni0.15Co0.1O2. All results demonstrated the feasibility of epitaxial growth for these materials, with the growth following the predicted cube-on-cube orientation relationship between the cubic and pseudo-cubic oxygen sublattices of a substrate and a film, respectively. Full article
(This article belongs to the Special Issue Crystallography of Functional Materials)
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Open AccessArticle Structure Determination and Luminescent Property Studies of the Single Crystal Na3Sm(BO3)2
Crystals 2017, 7(5), 129; doi:10.3390/cryst7050129
Received: 30 January 2017 / Revised: 25 April 2017 / Accepted: 28 April 2017 / Published: 5 May 2017
Cited by 1 | PDF Full-text (3643 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Sodium samarium borate Na3Sm(BO3)2, was prepared by a flux method and structurally characterized by single-crystal structure analysis for the first time. The results show that it crystallizes in the monoclinic system P21/n,
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Sodium samarium borate Na3Sm(BO3)2, was prepared by a flux method and structurally characterized by single-crystal structure analysis for the first time. The results show that it crystallizes in the monoclinic system P21/n, with a = 6.5667(3) Å, b = 8.7675(4) Å, c = 10.1850(5), β = 90.86°, V = 586.32(5) Å3 and Z = 4. The structure contains NaO7, NaO6, NaO5, SmO8, and BO3 units, which are interconnected via corner- or edge-sharing O atoms into a three-dimensional structure. The excitation spectra, emission spectra, decay time, and Commission International de l’Éclairage (CIE) chromaticity index of Na3Sm(BO3)2 were studied. Under near light excitation (406 nm), the powdered Na3Sm(BO3)2 shows the orange-red emission, which originates from the 4G5/26H9/2 and 4G5/26H7/2 transformation of Sm3+ ion. Full article
(This article belongs to the Special Issue Crystallography of Functional Materials)
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Open AccessFeature PaperArticle Crystal and Magnetic Structures in Layered, Transition Metal Dihalides and Trihalides
Crystals 2017, 7(5), 121; doi:10.3390/cryst7050121
Received: 20 March 2017 / Revised: 18 April 2017 / Accepted: 23 April 2017 / Published: 27 April 2017
Cited by 7 | PDF Full-text (1009 KB) | HTML Full-text | XML Full-text
Abstract
Materials composed of two dimensional layers bonded to one another through weak van der Waals interactions often exhibit strongly anisotropic behaviors and can be cleaved into very thin specimens and sometimes into monolayer crystals. Interest in such materials is driven by the study
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Materials composed of two dimensional layers bonded to one another through weak van der Waals interactions often exhibit strongly anisotropic behaviors and can be cleaved into very thin specimens and sometimes into monolayer crystals. Interest in such materials is driven by the study of low dimensional physics and the design of functional heterostructures. Binary compounds with the compositions M X 2 and M X 3 where M is a metal cation and X is a halogen anion often form such structures. Magnetism can be incorporated by choosing a transition metal with a partially filled d-shell for M, enabling ferroic responses for enhanced functionality. Here a brief overview of binary transition metal dihalides and trihalides is given, summarizing their crystallographic properties and long-range-ordered magnetic structures, focusing on those materials with layered crystal structures and partially filled d-shells required for combining low dimensionality and cleavability with magnetism. Full article
(This article belongs to the Special Issue Crystallography of Functional Materials)
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Open AccessArticle Synthesis, Crystal Structure, and Luminescent Properties of New Zinc(II) and Cadmium(II) Metal-Organic Frameworks Based on Flexible Bis(imidazol-1-yl)alkane Ligands
Crystals 2016, 6(10), 132; doi:10.3390/cryst6100132
Received: 1 September 2016 / Revised: 28 September 2016 / Accepted: 11 October 2016 / Published: 13 October 2016
Cited by 6 | PDF Full-text (3988 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
New metal-organic frameworks (MOFs) based on zinc and cadmium ions, terephthalic acid, and flexible ligands 1,5-bis(imidazol-1-yl)pentane or 1,6-bis(imidazol-1-yl)hexane were prepared and characterized by X-ray diffraction, thermorgavimetric analysis and IR spectroscopy. The imidazolyl ligands were prepared by a new robust procedure involving the reaction
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New metal-organic frameworks (MOFs) based on zinc and cadmium ions, terephthalic acid, and flexible ligands 1,5-bis(imidazol-1-yl)pentane or 1,6-bis(imidazol-1-yl)hexane were prepared and characterized by X-ray diffraction, thermorgavimetric analysis and IR spectroscopy. The imidazolyl ligands were prepared by a new robust procedure involving the reaction between imidazole and 1,5-dibromopentane or 1,6-dibromohexane in a superbasic medium (KOH in DMSO). MOFs based on 1,5-bis(imidazol-1-yl)pentane had diamond topology (dia) and are triply interpenetrated. Ligands with longer spacer 1,6-bis(imidazol-1-yl)hexane, terephthalate ions and zinc(II) ions formed five-fold interpenetrated metal-organic framework also with dia topology, while cadmium(II) ions with the same ligands formed eight-connected uninodal net with a very rare self-penetrated topological type ilc and a point symbol 424.5.63. The influence of the chemical composition of MOFs on their photoluminescent properties is investigated and discussed in detail. Full article
(This article belongs to the Special Issue Crystallography of Functional Materials)
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Review

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Open AccessReview Structural Aspects of Porphyrins for Functional Materials Applications
Crystals 2017, 7(7), 223; doi:10.3390/cryst7070223
Received: 19 April 2017 / Revised: 22 June 2017 / Accepted: 12 July 2017 / Published: 15 July 2017
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Abstract
Porphyrinic compounds comprise a diverse group of materials which have in common the presence of one or more cyclic tetrapyrroles known as porphyrins in their molecular structures. The resulting aromaticity gives rise to the semiconducting properties that make these compounds of interest for
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Porphyrinic compounds comprise a diverse group of materials which have in common the presence of one or more cyclic tetrapyrroles known as porphyrins in their molecular structures. The resulting aromaticity gives rise to the semiconducting properties that make these compounds of interest for a broad range of applications, including artificial photosynthesis, catalysis, molecular electronics, sensors, non-linear optics, and solar cells. In this brief review, the crystallographic attributes of porphyrins are emphasized. Examples are given showing how the structural orientations of the porphyrin macrocycle, and the inter-porphyrin covalent bonding present in multiporphyrins influence the semiconducting properties. Beginning with porphine, the simplest porphyrin, we discuss how the more complex structures that have been reported are described by adding peripheral substituents and internal metalation to the macrocycles. We illustrate how the conjugation of the π-bonding, and the presence of electron donor/acceptor pairs, which are the basis for the semiconducting properties, are affected by the crystallographic topology. Full article
(This article belongs to the Special Issue Crystallography of Functional Materials)
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Open AccessReview Polymorphism and Structural Distortions of Mixed-Metal Oxide Photocatalysts Constructed with α-U3O8 Types of Layers
Crystals 2017, 7(5), 145; doi:10.3390/cryst7050145
Received: 12 April 2017 / Revised: 12 May 2017 / Accepted: 14 May 2017 / Published: 18 May 2017
Cited by 1 | PDF Full-text (6926 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A series of mixed-metal oxide structures based on the stacking of α-U3O8 type pentagonal bipyramid layers have been investigated for symmetry lowering distortions and photocatalytic activity. The family of structures contains the general composition Am+((n+1)/m)
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A series of mixed-metal oxide structures based on the stacking of α-U3O8 type pentagonal bipyramid layers have been investigated for symmetry lowering distortions and photocatalytic activity. The family of structures contains the general composition Am+((n+1)/m)B(3n+1)O(8n+3) (e.g., A = Ag, Bi, Ca, Cu, Ce, Dy, Eu, Gd K, La, Nd, Pb, Pr, Sr, Y; B = Nb, Ta; m = 1–3; n = 1, 1.5, 2), and the edge-shared BO7 pentagonal pyramid single, double, and/or triple layers are differentiated by the average thickness, (i.e., 1 ≤ n ≤ 2), of the BO7 layers and the local coordination environment of the “A” site cations. Temperature dependent polymorphism has been investigated for structures containing single layered (n = 1) monovalent (m = 1) “A” site cations (e.g., Ag2Nb4O11, Na2Nb4O11, and Cu2Ta4O11). Furthermore, symmetry lowering distortions were observed for the Pb ion-exchange synthesis of Ag2Ta4O11 to yield PbTa4O11. Several members within the subset of the family have been constructed with optical and electronic properties that are suitable for the conversion of solar energy to chemical fuels via water splitting. Full article
(This article belongs to the Special Issue Crystallography of Functional Materials)
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Open AccessReview Structure Property Relationships and Cationic Doping in [Ca24Al28O64]4+ Framework: A Review
Crystals 2017, 7(5), 143; doi:10.3390/cryst7050143
Received: 20 March 2017 / Revised: 8 May 2017 / Accepted: 10 May 2017 / Published: 16 May 2017
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Abstract
Ca12Al14O33 (C12A7, 12CaO·7Al2O3, or [Ca12Al14O32]2+:O2) is a material with a clathrate cage framework, positively charged and stabilized by anions occluded
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Ca12Al14O33 (C12A7, 12CaO·7Al2O3, or [ Ca 12 Al 14 O 32 ] 2 + : O 2 ) is a material with a clathrate cage framework, positively charged and stabilized by anions occluded within 17% of the cages. The occluded anion is modular and can be elemental, polyatomic, and electronic in nature. This review focuses on the electride C12A7 ( [ Ca 24 Al 28 O 64 ] 4 + : ( 4 * ) e ( 2 ) O 2 ), where O2− anions are replaced with electrons, and compliments previous structural and electronic property reviews to illuminate the structure–property relationships. Electride formation is updated with new findings in carbonaceous reduction methods. Most importantly, an extensive compilation of cationic doped C12A7 isostructural compounds is presented as motivation to study doped C12A7 electrides. Cationic dopants have profound impacts on the electronic properties due to changes in the density of states, localized electron behavior, and structural distortions. Full article
(This article belongs to the Special Issue Crystallography of Functional Materials)
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