Polycrystalline Materials – from Design to (Micro)Structural Characterization and Applications

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

Deadline for manuscript submissions: 31 July 2024 | Viewed by 9727

Special Issue Editors


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Guest Editor
Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
Interests: crystallography; powder diffraction; structural and microstructural analysis; electrochemistry; batteries; thin films; mechanochemistry; metal-organic compounds

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Guest Editor
Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
Interests: crystallography, electrical properties; magnetic properties; materials science; thin films

Special Issue Information

Dear Colleagues,

Despite numerous attempts, it can be very challenging to obtain a single crystal with a straightforward structural solution. In recent years, the development of computer programs for solving structure solution and analyzing powder diffraction data has enabled the crystal structure of polycrystalline materials to be determined, making powder X-ray diffraction an even more valuable method. When it comes to synthetic procedures that exclusively produce polycrystalline material, for instance, mechanochemical synthesis, the use of powder X-ray diffraction is essential. This also applies to polycrystalline thin films.

It is possible not only to determine the purity of the sample, but also to determine new structures from powder X-ray diffraction data to obtain information about the microstructural features, porosity and thermal expansion of the material. The morphology of the sample can have a significant effect on its properties; therefore, we encourage any research findings that compare the properties of the same compound in different states, such as powders vs. thin films or single crystals. Additionally, even when it seems that X-ray diffraction data do not provide enough information to fully determine the structure of a material, the impossible becomes possible when combined with other analytical tools, such as solid-state NMR, IR spectroscopy, Raman, and many other techniques.

The main idea of this Special Issue is to relate synthetic processes to the crystal structure and microstructure of the compounds produced, as well as to the properties and potential applications. We invite all scientists, both synthetic chemists and colleagues working in the field of X-ray diffraction, microstructural analysis or software development for the analysis of powder diffraction data, to submit their research for evaluation and help to make this Special Issue a valuable contribution to the scientific community. In particular, if you have found a potential application of a material, such as a high conductivity, multiferroics, gas sorption/separation properties, interesting thermal expansion behavior, etc., you are invited to share your important findings with us.

We look forward to your contributions in the form of communications, full articles, or review papers.

Dr. Sanja Burazer
Dr. Lidija Androš Dubraja
Guest Editors

Manuscript Submission Information

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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 2600 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

  • structure determination from PXRD data
  • microstructural analysis
  • powder diffraction software
  • Rietveld refinement
  • polycrystalline thin films
  • synchrotron radiation
  • spin coating
  • mechanochemistry
  • solvothermal synthesis
  • electrochemical materials
  • magnetic materials
  • thermal expansion materials
  • porous materials

Published Papers (8 papers)

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Research

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18 pages, 4877 KiB  
Article
Removal of Organic Materials from Mytilus Shells and Their Morphological and Chemical-Physical Characterisation
by Alberto Ubaldini, Flavio Cicconi, Sara Calistri, Stefano Salvi, Chiara Telloli, Giuseppe Marghella, Alessandro Gessi, Stefania Bruni, Naomi Falsini and Antonietta Rizzo
Crystals 2024, 14(5), 464; https://doi.org/10.3390/cryst14050464 - 16 May 2024
Viewed by 510
Abstract
A simple and effective method to eliminate the organic component from mussel shells is presented. It is based on the use of hot hydrogen peroxide. Mollusc shells are composite materials made of a calcium carbonate matrix with different polymorphs and numerous biomacromolecules. The [...] Read more.
A simple and effective method to eliminate the organic component from mussel shells is presented. It is based on the use of hot hydrogen peroxide. Mollusc shells are composite materials made of a calcium carbonate matrix with different polymorphs and numerous biomacromolecules. The described method was used on mussel shells, but it is generalisable and allows the complete removal of these organic components, without altering the inorganic part. Specimens were kept in a H2O2 40% bath for few hours at 70 °C. The organic layers found on the faces of the shells were peeled away in this way, and biomacromolecules were degraded and removed. Their fragments are soluble in aqueous solution. This easily permits the chemical-physical characterisation and the study of the microstructure. The quality of calcite and aragonite microcrystals of biogenic origin is very high, superior to that of materials of geological or synthetic origin. This may suggest various industrial applications for them. Calcium carbonate is a useful precursor for cements and other building materials, and the one obtained in this way is of excellent quality and high purity. Full article
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19 pages, 3717 KiB  
Article
CO2 Promoting Polymorphic Transformation of Clarithromycin: Polymorph Characterization, Pathway Design, and Mechanism Study
by Lixin Hou, Dingding Jing, Yanfeng Wang and Ying Bao
Crystals 2024, 14(5), 394; https://doi.org/10.3390/cryst14050394 - 24 Apr 2024
Viewed by 553
Abstract
Carbon dioxide (CO2) has a wide range of uses such as food additives and raw materials for synthetic chemicals, while its application in the solid-state transformation of pharmaceutical crystals is rare. In this work, we report a case of using 1 [...] Read more.
Carbon dioxide (CO2) has a wide range of uses such as food additives and raw materials for synthetic chemicals, while its application in the solid-state transformation of pharmaceutical crystals is rare. In this work, we report a case of using 1 atm CO2 as an accelerator to promote the polymorphic transformation of clarithromycin (CLA). Initially, crystal structures of Form 0′ and three solvates were successfully determined by single crystal X-ray diffraction (SCXRD) analysis for the first time and found to be isomorphous. Powder X-ray diffraction (PXRD) and thermal analysis indicated that the solvate desolvates and transforms into the structurally similar non-solvated Form 0′ at room temperature to ~50 °C. Form 0′ and Form II are monotropically related polymorphs with Form II being the most stable. Subsequently, the effect of CO2 on the transformation of CLA solvates to Form II was studied. The results show that CO2 can significantly facilitate the transformation of Form 0′ to Form II, despite no significant effect on the desolvation process. Finally, the molecular mechanism of CO2 promoting the polymorphic transformation was revealed by the combination of the measurement of adsorption capacity, theoretical calculations as well as crystal structure analysis. Based on the above results, a new pathway of preparing CLA Form II was designed: transform CLA solvates into Form 0′ in 1 atm air at 50 °C followed by the transformation of Form 0′ to Form II in 1 atm CO2 at 50 °C. This work provides a new idea for promoting the phase transformation of pharmaceutical crystals as well as a new scenario for the utilization of CO2. Full article
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17 pages, 8162 KiB  
Article
Fine Tuning of Hierarchical Zeolite Beta Acid Sites Strength
by Ivana Landripet, Andreas Puškarić, Marko Robić and Josip Bronić
Crystals 2024, 14(1), 53; https://doi.org/10.3390/cryst14010053 - 29 Dec 2023
Viewed by 894
Abstract
Two different synthesis methods to obtain hierarchical Beta zeolite are investigated: direct synthesis using cetyltrimethylammonium bromide (CTAB) as a mesoporous template and post-synthesis desilication by etching with NaOH and TPAOH. The main focus of this study is to show the possibility of fine [...] Read more.
Two different synthesis methods to obtain hierarchical Beta zeolite are investigated: direct synthesis using cetyltrimethylammonium bromide (CTAB) as a mesoporous template and post-synthesis desilication by etching with NaOH and TPAOH. The main focus of this study is to show the possibility of fine tuning of the acid site (OH) strength (Brønsted and Lewis acid sites) through wet impregnation of these hierarchical Beta zeolites with divalent metal cations (Mg2+, Co2+, Ni2+, Cu2+, and Zn2+), which are important for various applications. Fourier transform infrared spectroscopy (FTIR) and deuterated acetonitrile as the probe molecule were used as a powerful technique to analyze the quantity and number of Brønsted/Lewis acid sites in the modified zeolite Beta structure. Investigating the influence of different divalent metal cations with a comparable ionic radius on the acidity of the hierarchical Beta zeolites, the present research aims to shed light on the structure–activity relationship that determines their catalytic behavior, for the development of efficient and environmentally friendly catalysts for various industrial applications. Full article
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18 pages, 5830 KiB  
Article
Supramolecular Structure, Hirshfeld Surface Analysis, Morphological Study and DFT Calculations of the Triphenyltetrazolium Cobalt Thiocyanate Complex
by Essam A. Ali, Rim Bechaieb, Rashad Al-Salahi, Ahmed S. M. Al-Janabi, Mohamed W. Attwa and Gamal A. E. Mostafa
Crystals 2023, 13(11), 1598; https://doi.org/10.3390/cryst13111598 - 19 Nov 2023
Cited by 1 | Viewed by 1022
Abstract
Polymorphism is a prevalent occurrence in pharmaceutical solids and demands thorough investigation during product development. This paper delves into the crystal growth and structure of a newly synthesized polymorph (TPT)2[CoII(NCS)4], (1), where TPT is triphenyl tetrazolium. The [...] Read more.
Polymorphism is a prevalent occurrence in pharmaceutical solids and demands thorough investigation during product development. This paper delves into the crystal growth and structure of a newly synthesized polymorph (TPT)2[CoII(NCS)4], (1), where TPT is triphenyl tetrazolium. The study combines experimental and theoretical approaches to elucidate the 3D framework of the crystal structure, characterized by hydrogen-bonded interactions between (TPT)+ cations and [Co(NCS)4]2− anions. Hirshfeld surface analysis, along with associated two-dimensional fingerprints, is employed to comprehensively investigate and quantify intermolecular interactions within the structure. The enrichment ratio is calculated for non-covalent contacts, providing insight into their propensity to influence crystal packing interactions. Void analysis is conducted to predict the mechanical behavior of the compound. Utilizing Bravais-Friedel, Donnay-Harker (BFDH), and growth morphology (GM) techniques, the external morphology of (TPT)2[CoII(NCS)4] is predicted. Experimental observations align well with BFDH predictions, with slight deviations from the GM model. Quantum computational calculations of the synthesized compounds is performed in the ground state using the DFT/UB3LYP level of theory. These calculations assess the molecule’s stability and chemical reactivity, including the computation of the HOMO-LUMO energy difference and other chemical descriptors. The study provides a comprehensive exploration of the newly synthesized polymorph, shedding light on its crystal structure, intermolecular interactions, mechanical behavior, and external morphology, supported by both experimental and computational analyses. Full article
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17 pages, 11304 KiB  
Article
Research on Microstructure, Synthesis Mechanisms, and Residual Stress Evolution of Polycrystalline Diamond Compacts
by Peishen Ni, Yongxuan Chen, Wenxin Yang, Zijian Hu and Xin Deng
Crystals 2023, 13(8), 1286; https://doi.org/10.3390/cryst13081286 - 20 Aug 2023
Viewed by 1178
Abstract
The microstructure and residual stress of polycrystalline diamond compact (PDC) play crucial roles in the performance of PDCs. Currently, in-depth research is still to be desired on the evolution mechanisms of microstructure and residual stress during high pressure high temperature (HPHT) synthesis process [...] Read more.
The microstructure and residual stress of polycrystalline diamond compact (PDC) play crucial roles in the performance of PDCs. Currently, in-depth research is still to be desired on the evolution mechanisms of microstructure and residual stress during high pressure high temperature (HPHT) synthesis process of PDCs. This study systematically investigated the influencing mechanisms of polycrystalline diamond (PCD) layer material design, especially the Co content of the PCD layer, on microstructure and residual stress evolution in PDCs via Raman spectroscopy and finite element micromechanical simulation. The research shows that when the original Co content of the PCD layer is higher than 15 wt.%, the extra Co in the PCD layer will migrate backwards towards the carbide substrate and form Co-enrichment regions at the PCD–carbide substrate interface. As the original Co content of the PCD layer increases from 13 to 20 wt.%, the residual compressive stress of diamond phase at the upper surface center of the PCD layer gradually decreases and transforms into tensile stress. When the original Co content of the PCD layer is as high as 30 wt.%, the residual stress transforms back into significant compressive stress again. The microstructure-based micromechanical simulation at the PCD–carbide substrate interface shows that the Co-enrichment region is the key for the transformation of the residual stress of the diamond phase from tensile stress into significant compressive stress. Full article
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12 pages, 6988 KiB  
Article
The Influence of Inserted Metal Ions on Acid Strength of OH Groups in Faujasite
by Glorija Medak, Andreas Puškarić and Josip Bronić
Crystals 2023, 13(2), 332; https://doi.org/10.3390/cryst13020332 - 16 Feb 2023
Cited by 2 | Viewed by 1318
Abstract
The number and the strength of acid sites in catalysts have paramount importance on their efficiency. In zeolites chemistry, increased content of framework Al in zeolites gives a higher number of strong acid sites. Their strength can be a disadvantage in catalytic reactions [...] Read more.
The number and the strength of acid sites in catalysts have paramount importance on their efficiency. In zeolites chemistry, increased content of framework Al in zeolites gives a higher number of strong acid sites. Their strength can be a disadvantage in catalytic reactions (e.g., methanol to olefins conversion) due to undesired secondary reactions of coke formation. Here, the Faujasite type of zeolite with higher content of Al has been used for investigating the role of defects in structure and inserted (wet impregnation and thermal treatment) metal cations (Mg, Co, Ni, Zn) on the strength of OH acid sites. Desorption of deuterated acetonitrile, as a probe molecule, was used for OH groups acid strength measurements at different temperatures (150, 200, and 300 °C). Full article
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17 pages, 6295 KiB  
Article
Electrochemical Investigation of the OER Activity for Nickel Phosphite-Based Compositions and Its Morphology-Dependent Fluorescence Properties
by Maria Poienar, Paula Svera, Bogdan-Ovidiu Taranu, Catalin Ianasi, Paula Sfirloaga, Gabriel Buse, Philippe Veber and Paulina Vlazan
Crystals 2022, 12(12), 1803; https://doi.org/10.3390/cryst12121803 - 12 Dec 2022
Cited by 2 | Viewed by 1315
Abstract
Herein, we present the investigation of catalytical and fluorescence properties for Ni11(HPO3)8(OH)6 materials obtained through a hydrothermal approach. As part of the constant search for new materials that are both cost effective and electrocatalytically active for [...] Read more.
Herein, we present the investigation of catalytical and fluorescence properties for Ni11(HPO3)8(OH)6 materials obtained through a hydrothermal approach. As part of the constant search for new materials that are both cost effective and electrocatalytically active for the oxygen evolution reaction (OER) in alkaline medium, the present study involves several graphite electrodes modified with Ni11(HPO3)8(OH)6 mixed with reduced graphene oxide (rGO) and carbon black. The experimental results obtained in 0.1 mol L–1 KOH electrolyte solution show the electrode modified with rGO, 5 mg carbon black and 1 mg nickel phosphite as displaying the highest current density. This performance can be attributed to the synergistic effect between nickel phosphite and the carbon materials. Investigation of the electrode’s OER performance in 0.1 mol L–1 KOH solution revealed a Tafel slope value of just 46 mV dec–1. By increasing the concentration to 0.5 and 1 mol L–1, this value increased as well, but there was a significant decrease in overpotential. Fluorescence properties were analyzed for the first time at the excitation length of 344 nm, and the observed strong and multiple emissions are described. Full article
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Review

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15 pages, 3398 KiB  
Review
Structure–Superstructure Inter-Relations in Ca2SiO4 Belite Phase
by Vassilis Psycharis, Manolis Chatzigeorgiou, Dimitra Koumpouri, Margarita Beazi-Katsioti and Marios Katsiotis
Crystals 2022, 12(12), 1692; https://doi.org/10.3390/cryst12121692 - 23 Nov 2022
Cited by 1 | Viewed by 2017
Abstract
Belite, the second most abundant mineralogical phase in Portland cement, presents five polymorphs which are formed at different temperatures. The increased interest in belite cement-based products is due to the lower environmental impact associated with the lower energy consumption. The importance of belite [...] Read more.
Belite, the second most abundant mineralogical phase in Portland cement, presents five polymorphs which are formed at different temperatures. The increased interest in belite cement-based products is due to the lower environmental impact associated with the lower energy consumption. The importance of belite polymorphs formed at higher temperatures for cement industry applications is high, because they present better hydraulic properties. Thus, any study that helps to explore the structure relations of all belite polymorphs is of interest for both scientific and practical points of view. In the present work, a systematic structure–superstructure relation study is presented for all polymorphs, and it is based on the work of O’Keefe and Hyde (1985). In this pioneering work, generally, the structures of oxides are considered as having common characteristics with prototype structures of alloys. The basic result of the present work is the fact that all the polymorphs adopt a common architecture which is based on capped trigonal prisms of Ca cations, which host the Si one, and the oxygen anions occupy interstitial sites, i.e., an architecture in conformity with the model which considers the oxide structures as stuffed alloys. This result supports the displacive character of the transformation structural mechanism that links the five polymorphs based on the cation sites in their structures. However, based on the sites of oxygen anions, it could be considered as of diffusion character. The study of belite polymorphs is also of interest to products obtained by doping dicalcium silicate compounds, which present interesting luminescent properties. Full article
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