Special Issue "Compounds with Polar Metallic Bonding"

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

Deadline for manuscript submissions: closed (31 March 2018)

Special Issue Editor

Guest Editor
Dr. Constantin Hoch

LMU Munich, Department for Chemistry, Butenandtstraße 5-13(D), D-81377 München, Germany
Website | E-Mail
Interests: preparative inorganic chemistry; intermetallics; polar metals; subvalent compounds; crystallography; solid state chemistry; nitrido- and oxometalates; amalgams

Special Issue Information

Dear Colleagues,

This Special Issue on “Compounds with Polar Metallic Bonding” is intended to open an exchange between chemical, physical and material-oriented disciplines committed to intermetallic systems with strongly correlated electrons. The term “polar metal” is ubiquitous here, and can describe numerous different effects. Polarity can indicate the interplay of conduction electrons with magnetic dipoles in the lattice. It can also describe the presence of electric dipole moments within a ferroelectric metal. Additionally, the term is used when referring to an intermetallic phase crystallising in a polar space group, or when electronegativity differences between the constituent elements of an intermetallic phase induce Coulombic interactions within an overall metallic matrix.

In all these cases, polarity induces new, interesting property combinations in metallic systems. To understand the mechanisms in this field, it is necessary to understand interplay between localised moments, as electric or magnetic dipoles, as well as Coulombic monopoles with the delocalized conduction electrons. For the establishment of structure–property relations for compounds with polar metallic bonding it is indispensable to present reliable models of their electronic structures. In order to understand the electronic consequences of polarity on the basis of quantum-mechanical calculations, it is necessary to have detailed crystal structure models at hand. Additionally, prior to crystal structure elucidation there is, of course, chemical synthesis.

We would like to combine reports on all related topics in this special issue. Some specifically interesting topics that may be included are listed below as keywords. These should only be considered as examples—any advanced topic in the field of polar metallic bonding is welcome.

Dr. Constantin Hoch
Guest Editor

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 1200 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.


  • Synthesis of compounds with polar metallic bonding
  • Crystal structure reports in polar intermetallics
  • Band structure calculations and electronic structure modelling
  • Physical properties and structure-property relations
  • Bulk phases, thin films and cocrystals of polar intermetallic systems
  • Polar metallic systems in applications

Published Papers (1 paper)

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Open AccessArticle Crystal Structure, Spectroscopic Investigations, and Physical Properties of the Ternary Intermetallic REPt2Al3 (RE = Y, Dy–Tm) and RE2Pt3Al4 Representatives (RE = Tm, Lu)
Crystals 2018, 8(4), 169; doi:10.3390/cryst8040169
Received: 1 March 2018 / Revised: 9 April 2018 / Accepted: 10 April 2018 / Published: 16 April 2018
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The REPt2Al3 compounds of the late rare-earth metals (RE = Y, Dy–Tm) were found to crystallize isostructural. Single-crystal X-ray investigations of YPt2Al3 revealed an orthorhombic unit cell (a = 1080.73(6), b = 1871.96(9), c
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The REPt2Al3 compounds of the late rare-earth metals (RE = Y, Dy–Tm) were found to crystallize isostructural. Single-crystal X-ray investigations of YPt2Al3 revealed an orthorhombic unit cell (a = 1080.73(6), b = 1871.96(9), c = 413.04(2) pm, wR2 = 0.0780, 942 F2 values, 46 variables) with space group Cmmm (oC48; q2pji2hedb). A comparison with the Pearson database indicated that YPt2Al3 forms a new structure type, in which the Pt and Al atoms form a [Pt2Al3]δ polyanion and the Y atoms reside in the cavities within the framework. Via a group-subgroup scheme, the relationship between the PrNi2Al3-type structure and the new YPt2Al3-type structure was illustrated. The compounds with RE = Dy–Tm were characterized by powder X-ray diffraction experiments. While YPt2Al3 is a Pauli-paramagnet, the other REPt2Al3 (RE = Dy–Tm) compounds exhibit paramagnetic behavior, which is in line with the rare-earth atoms being in the trivalent oxidation state. DyPt2Al3 and TmPt2Al3 exhibit ferromagnetic ordering at TC = 10.8(1) and 4.7(1) K and HoPt2Al3 antiferromagnetic ordering at TN = 5.5(1) K, respectively. Attempts to synthesize the isostructural lutetium compound resulted in the formation of Lu2Pt3Al4 (Ce2Ir3Sb4-type, Pnma, a = 1343.4(2), b = 416.41(8), c = 1141.1(2) pm), which could also be realized with thulium. The structure was refined from single-crystal data (wR2 = 0.0940, 1605 F2 values, 56 variables). Again, a polyanion with bonding Pt–Al interactions was found, and the two distinct Lu atoms were residing in the cavities of the [Pt3Al4]δ framework. X-ray photoelectron spectroscopy (XPS) measurements were conducted to examine the electron transfer from the rare-earth atoms onto the polyanionic framework. Full article
(This article belongs to the Special Issue Compounds with Polar Metallic Bonding)

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