Metastable-Phase Materials E-Book
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- Herausgeber: Wiley-VCH GmbH
- Kategorie: Fachliteratur
- Sprache: Englisch
- Veröffentlichungsjahr: 2024
This book summarizes an arising branch of materials, metastable materials, which are rarely discussed before and addresses their applications in catalytic reactions.
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Table of Contents
Cover
Table of Contents
Title Page
Copyright
Foreword
Preface
1 Introduction of the Metastable‐Phase Materials
1.1 Introduction
1.2 What Are Metastable‐Phase Materials?
1.3 The Categories of Metastable‐Phase Materials
1.4 The Influence on Polymorphs of Materials
1.5 The Wide Applications of Metastable‐Phase Materials
1.6 The Criterion for Stable‐Phase and Metastable‐Phase Materials
References
2 Synthetic Methodology
2.1 Introduction
2.2 The Key for Synthesizing Metastable‐Phase Materials
2.3 The Synthetic Methods for Synthesizing Metastable‐Phase Materials
References
3 Characterization
3.1 Introduction
3.2 Characterizations
3.3 How to Determine the Phase of Metastable‐Phase 2D Metal Oxides
References
4 Metastable‐Phase Metals
4.1 Introduction
4.2 Noble Metals
4.3 Non‐noble Metals
4.4 The Criterion to Determine the Stable‐Phase and Metastable‐Phase Metals
References
5 Metastable‐Phase Oxide, Chalcogenide, Phosphide, and Boride Materials
5.1 Introduction
5.2 Oxides
5.3 Chalcogenides
5.4 Others
References
6 Spin‐Dependent Metastable‐Phase Materials
6.1 Introduction
6.2 Spin‐Related Catalysis
6.3 Spin‐Related Catalysts for Alkaline OER
6.4 Spin‐Related Catalyst for Acidic OER
References
7 Crystallography, Design, and Synthesis of Two‐Dimensional Metastable‐Phase Oxides
7.1 Introduction
7.2 The Point Group, Crystal System, Crystal Lattice, and Space Groups of 2D Materials
7.3 The Possible Crystal Structures and Chemical Formula of 2D Metal Oxides
7.4 How to Prepare Metastable‐Phase 2D Metal Oxides
7.5 2D Metastable‐Phase Noble Metal Oxides
7.6 Metastable‐Phase 2D Non‐noble Metal Oxides
7.7 The Covalent Bond Behavior in Metastable‐Phase 1T Metal Oxides
References
8 Electrocatalysis
8.1 Introduction
8.2 Several Typical Electrochemical Reactions
8.3 Metastable‐Phase Catalysts for Advanced Electrocatalysis
References
9 Photocatalysis
9.1 Introduction
9.2 Fundamental Concepts of Photocatalysis
9.3 Metastable‐Phase Catalysts and Photocatalysis
9.4 The Advantages and Disadvantages of Photocatalysis
References
10 Thermocatalysts
10.1 Introduction
10.2 Several Typical Thermocatalytic Reactions
10.3 Metastable‐Phase Catalysts for Thermocatalysis
References
Summary and Outlook
Index
End User License Agreement
List of Tables
Chapter 1
Table 1.1 The effect of temperature on polymorphs.
Table 1.2 The effect of pressure on polymorphs.
Table 1.3 The criterion to determine stable‐phase and metastable‐phase for r...
Chapter 3
Table 3.1 Systematic Absences for X‐Ray and Electron Diffraction
Chapter 4
Table 4.1 The crystal structures and cell parameters of the stable‐phase nob...
Table 4.2 Crystal structure and cell parameters of the stable‐phase non‐nobl...
Table 4.3 The criterion to determine the stable‐phase and metastable‐phase m...
Chapter 5
Table 5.1 Crystallographic information for rutile, anatase, and brookite TiO
Table 5.2 Crystallographic information for α...
Table 5.3 Crystallographic information for Wurtzite ZnO and Zincblende ZnO....
Table 5.4 Crystallographic information for stable‐phase graphite, metastable...
Chapter 7
Table 7.1 The summary of 10 elements in the layer point group, 4‐layer cryst...
Table 7.2 The summary of 5‐layer crystal lattices.
Table 7.3 Summary of the possible 2D single‐layer metallene oxides based on ...
Table 7.4 The summary of the radius ratio for a given polyhedron or polygon....
Table 7.5 The summary of 192 kinds of binary metallene oxides, which may for...
Table 7.6 Crystallographic information for 1T‐IrO
2
, 3R‐IrO
2
, and monoclinic‐...
Table 7.7 The MO lengths of common oxides with rutile structure.
Table 7.8 The MO lengths of synthesized 1T oxides.
Table 7.9 The forces constants of 1T‐ and Rutile IrO
2
.
Chapter 8
Table 8.1 The summary of metastable‐phases Au and Ag.
Table 8.2 The summary of metastable‐phase Ru and Rh.
Table 8.3 The summary of OER performances of metastable‐phase 2D iridium oxi...
Chapter 9
Table 9.1 Crystallographic and physical properties of rutile, anatase, and b...
List of Illustrations
Chapter 1
Figure 1.1 The schematic of metastable‐phase and stable‐phase. The red ball ...
Figure 1.2 The crystal structures of (a) α‐Ni and (b) β‐Ni.
Figure 1.3 The crystal structures of (a) rutile‐, (b) anatase‐, and (c) broo...
Figure 1.4 The crystal structures of (a) α‐ and (b) γ‐Fe.
Figure 1.5 The crystal structures of (a) α‐ and (b) β‐Sn.
Figure 1.6 The crystal structures of (a) graphite and (b) diamond.
Figure 1.7 The crystal structures of FeAl alloy at (a) low and (b) high temp...
Chapter 2
Figure 2.1 The schematic of how to synthesize metastable‐phase materials.
Figure 2.2 The schematic of ball‐milling process.
Figure 2.3 The schematic of hydrothermal process.
Figure 2.4 Characterization of stabilized metastable catalyst. (a) Schematic...
Figure 2.5 The schematic of high‐pressure equipment.
Figure 2.6 (a) The SEM and (b) TEM images of 1T‐IrO
2
, representing ultrathin...
Chapter 3
Figure 3.1 The schematic of X‐ray diffraction. The red balls represent the l...
Figure 3.2 Comparison of XRD patterns of 1T‐IrO
2
(red curve), simulation X‐r...
Figure 3.3 Metastable 3R‐RhO
2
: (a) TEM image.(b) ED pattern, (c) HRTEM i...
Figure 3.4 Structure representations of 1T‐IrO
2
. (a) Ir‐LIII edge XANES of 1...
Figure 3.5 Magnetic analysis of Mn‐RuO
2
NFs. (a) Magnetization hysteresis M–...
Chapter 4
Figure 4.1 (a) Characterizations of 2H–Au SSs. (i) TEM image of AuSSs on a G...
Figure 4.2 Ag nanowires selected from GS‐Ag nanowires sample after heating: ...
Figure 4.3 Morphology characterizations of RhMo NSs. (a,b) HAADF‐STEM images...
Figure 4.4 Structural analysis of RhMo NSs. (a) HAADF‐STEM image from a sing...
Figure 4.5 (a) Low‐magnification TEM images. (b) XRD patterns of the
hcp
‐Ni@...
Figure 4.6 Synthesis and electronic interactions of a coherent metastable
hc
...
Figure 4.7 Electronic structure characterization of
hcp
Ir–Ni. (a) A model o...
Figure 4.8 TEM images of (a) 12 nm, (b) 18 nm, (c) 22 nm, and (d) 26 nm Pd@R...
Figure 4.9 (a) The calculation of formation energy (Ef) and phases of
hcp
Ni...
Figure 4.10 Map of volume–temperature heating paths for
fcc
Co. Five cycles ...
Figure 4.11 (a) The crystal structure of metastable‐phase...
Chapter 5
Figure 5.1 The crystal structure of stable‐phase rutile TiO
2
with style: (a)...
Figure 5.2 The crystal structure of metastable‐phase anatase TiO
2
with style...
Figure 5.3 The crystal structure of metastable‐phase brookite TiO
2
with styl...
Figure 5.4 The crystal structure of (a) α‐, (b) β‐...
Figure 5.5 The crystal structures of (a) stable‐phase wurtzite ZnO and (b) m...
Figure 5.6 The crystal structure of (a) stable‐phase MoS
2
and (b) metastable...
Figure 5.7 Theoretically calculated (based on density functional theory) the...
Figure 5.8 The crystal structures of (a) stable‐phase graphite. (b) Metastab...
Chapter 6
Figure 6.1 The schematic illustration of the experimental setup by applying ...
Figure 6.2 Spin‐pinning effect for triplet oxygen evolution on the oxyhydrox...
Figure 6.3 Electrochemical performance of the catalysts. (a) Schematic illus...
Chapter 7
Figure 7.1 The evolution from graphene to metallene oxides. The fascinating ...
Figure 7.2 The single unit of single‐layered metallene oxides. (a) CN of 3: ...
Figure 7.3 The single unit of single‐layered metallene oxides. (a) CN of 3: ...
Figure 7.4 The distribution of possible single‐layer metallene oxides in the...
Figure 7.5 Schematic diagram of the alkali‐assisted mechanothermal method....
Figure 7.6 The crystal structure of (a–c) stable‐phase and metastable‐phase ...
Figure 7.7 The crystal structure of metastable monoclinic 2D IrO
2
NR.
Figure 7.8 (a) SEM image showing the uniform distribution of the IrO
2
NR. (b)...
Figure 7.9 TEM image of IrO
2
NR. TEM images show nanoribbon morphology in a l...
Figure 7.10 The crystal structures of (a–c) α‐phase...
Figure 7.11 (a) Schematic representation of the synthesis of 1T‐PtO
2
by the ...
Figure 7.12 The crystal structures of (a–c) rutile structure and (d–f) metas...
Figure 7.13 (a) XRD pattern and its enlarged view. (b) The SEM and (c) TEM i...
Figure 7.14 The crystal structures of (a–c) rutile structure and (d–f) metas...
Figure 7.15 The crystal structure of (a and b) fcc‐phase and (c) metastable‐...
Figure 7.16 The crystal structures of (a, b) monoclinic
P
2
1
/
c
phase. (c, d) ...
Figure 7.17 (a) Sn K‐edge XANES of h‐SnO
2
, commercial‐SnO
2
, SnO, and Sn foil...
Figure 7.18 A model of hydrogen bond.
Figure 7.19 (a, b) The SEM and TEM images of 1T‐IrO
2
. (c) (d) The crystal st...
Chapter 8
Figure 8.1 (a) Schematic illustration of a unit cell (top panel) and (101)
f
...
Figure 8.2 (a) TEM image of RuCu.(b) TEM image of RhMo.
Figure 8.3 Characterization of P‐
hcp
Ni. (a) Schematic structures of
fcc
Ni,...
Figure 8.4 Morphological and structural characterization of
hcp
RuNi. (a) Sy...
Figure 8.5 (a,d) HAADF‐STEM images of the monolayer and multilayer 1T‐IrO
2
, ...
Figure 8.6 (a) Polarization curves of 1T‐IrO
2
, rutile‐IrO
2
, and commercial c...
Figure 8.7 (a) The schematic synthesis of the microwave‐assisted mechano‐the...
Figure 8.8 (a) The OER polarization curves of 3R‐IrO
2
, rutile‐IrO
2
, C‐IrO
2
, ...
Figure 8.9 (a,b) The free‐energy profiles of OER over (a) 3R‐IrO
2
and (b) ru...
Figure 8.10 (a) SEM image and (b) TEM image of Am‐IrO
2
. (c) STEM‐EDS element...
Figure 8.11 (a) Formation energies of oxygen single vacancy and double vacan...
Figure 8.12 (a) LSV curves of the IrO
2
NR, IrO
2
NS, C‐IrO
2
, and C‐Ir/C samples...
Figure 8.13 (a) Polarization curves of the h‐SnO
2
, Commercial‐SnO
2
and rutil...
Figure 8.14 (a) Schematic representation for in situ growth of molecular‐sca...
Figure 8.15 (a) The HER polarization curves of Rh‐NA/RhO
2
, Rutile‐RhO
2
, C‐Rh...
Figure 8.16 (a) The schematic representation of hydrogen spillover assisted ...
Figure 8.17 (a) LSV curves of N‐MoS
2
/rGO, N‐MoS
2
, MoS
2
/rGO, and Pt/C. (b) Ta...
Figure 8.18 Physical characterization of monoclinic Pd
6
P/CNT catalyst. (a) T...
Figure 8.19 GOR performance of different electrocatalysts. (a) CVs in 1.0 M ...
Chapter 9
Figure 9.1 The schematic of photocatalysis mechanism.
Figure 9.2 Linear relations between band gap vs CB and VB for Ag
x
In
x
Zn
2−2x
...
Figure 9.3 The crystal structures of (a) α‐ and (b) β‐Bi
2
O
3
.
Figure 9.4 TEM images of the (a) Few layer MoS
2
.(b) Bulk MoS
2
.(c) Cu...
Chapter 10
Figure 10.1 The crystal structure of β‐MoO
3
with space group of P2
1
/c.
Figure 10.2 The crystal structure of metastable‐phase MoO
3
with space group ...
Figure 10.3 The crystal structure of metastable‐phases: (a) CuO with space g...
Figure 10.4 The crystal structure of metastable‐phase In
2
O
3
with space group...
Figure 10.5 The crystal structure of metastable‐phase AgBiO
3
with space grou...
Figure 10.6 Comparison of phenylacetylene hydrogenation performance between ...
Figure 10.7 (a) H
2
yields of MoS
1.75
Se
0.25
at various reaction times. (b) H
2
Figure 10.8 The crystal structure of metastable‐phase χ‐...
Guide
Cover
Table of Contents
Title Page
Copyright
Foreword
Preface
Begin Reading
Summary and Outlook
Index
End User License Agreement
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Metastable‐Phase Materials
Synthesis, Characterization, and Catalytic Applications
Edited by
Qi Shao, Zhenhui Kang, and Mingwang Shao
Editors
Prof. Qi ShaoSoochow UniversityCollege of Chemistry, ChemicalEngineering and Materials ScienceSuzhou 215123China
Prof. Zhenhui KangSoochow UniversityInstitute of Functional Nano & SoftMaterials (FUNSOM), Jiangsu KeyLaboratory for Carbon‐BasedFunctional Materials and DevicesSuzhou 215123China
Prof. Mingwang ShaoSoochow UniversityInstitute of Functional Nano & SoftMaterials (FUNSOM), Jiangsu KeyLaboratory for Carbon‐BasedFunctional Materials and DevicesSuzhou 215123China
Cover Image: © imagenavi/Getty Images
All books published by WILEY‐VCH are carefully produced. Nevertheless, authors, editors, and publisher do not warrant the information contained in these books, including this book, to be free of errors. Readers are advised to keep in mind that statements, data, illustrations, procedural details or other items may inadvertently be inaccurate.
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© 2024 WILEY‐VCH GmbH, Boschstraße 12, 69469 Weinheim, Germany
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Print ISBN: 978‐3‐527‐35105‐3ePDF ISBN: 978‐3‐527‐83981‐0ePub ISBN: 978‐3‐527‐83982‐7oBook ISBN: 978‐3‐527‐83983‐4
Foreword
At present, there are three issues awaiting human beings to be addressed: rational development and use of energy, developing new materials with superior performance, and protecting the environment in which we live. All these issues are closely related to catalysis.
First of all, materials are the symbol of the development of human society, and the synthesis of materials is the premise and basis of the development of materials science. Metastable‐phase materials enrich the content of materials, and the rapid rise of nanoscience and technology gives metastable‐phase materials new vitality. As metastable‐phase materials have higher free energy than stable ones, it is very likely for them to have good catalytic performance.
The research of catalytic processes has become one of the most active topics in the fields of chemistry and chemical engineering, because most chemical reactions rely on catalysts to accelerate the reaction rate or improve their selectivity. At present, the rational and effective use of catalysts in energy, environment, and other processes is more urgent. However, it is still difficult to rationally and effectively use catalysts because the catalytic processes are quite complex, including the study of catalyst structure and catalytic mechanism, which requires the participation of researchers in a variety of disciplines.
For this reason, I believe that the efforts to combine materials science and catalytic science must be fruitful and have great theoretical and practical significance in energy, chemistry, chemical industry, environment, and other fields.
This book does just that, providing representative content and insights on both crystalline structure and catalysis of catalysts, illustrating the relationship between the structure of metastable‐phase materials and catalytic properties, and demonstrating the richness of metastable‐phase materials and the complexity of catalytic processes. At the end of the book, the authors also point out the prospects for the future development of metastable‐phase materials and catalytic processes, which is certainly very meaningful.
It should also be noted that I have known the authors of this book for many years and know that they have rich experience in teaching and researching in both theoretical and experimental aspects, as well as good desire and enthusiasm for writing. This book focuses on their research achievements in the synthesis of metastable‐phase materials and the catalytic processes, such as two‐dimensional metastable‐phase oxides, metastable‐phase metals, and spin‐related metastable phases. Combined with the latest research progress in related fields at home and abroad, the content is rich and detailed. It is believed that the publication of this book will help people to understand and master the basic knowledge about the synthesis, characterization, and catalytic properties of metastable‐phase materials. The readers may get enlightenment from this book and then expand the application of metastable‐phase materials in many fields.
Xiaoqing Huang
State Key Laboratory of Physical Chemistry of Solid Surfaces
College of Chemistry and Chemical Engineering
Xiamen University
Xiamen 361005, China
Preface
Metastable‐phase materials are in a thermodynamically unstable state. However, they can exist under certain conditions. Metastable‐phase materials are numerous. For simple chemical compounds, the ratio of metastable‐phase materials is not large compared to the stable‐phase counterparts. For organic ones and polymers, the number of metastable‐phase compounds becomes dramatically large. For biological materials, nearly 100% phases are metastable ones.
Compared to their stable‐phase materials, metastable‐phase oxides have higher Gibbs free energy, various stoichiometries, diverse crystal structures, and unique coordination environment. For example, metastable‐phase 2D oxides are quite famous for their large surface area, edge‐sharing connection, hopping conduction pathway, and unusual magnetic property, thereby leading to fascinating new properties and promising applications.
Inspired by the recent great progress of metastable‐phase materials, in this book, we aim to provide a timely account of the latest progress of metastable‐phase materials. First of all, we introduce how to synthesize metastable‐phase materials. Several synthetic methods, including mechanical‐energy‐related methods, thermal‐energy‐related methods, and the combined method, are also introduced. Then the commonly used characterizations for structural, morphological, and spectroscopic information of metastable‐phase materials are mainly discussed. In the following chapters, the metastable‐phase metals, oxides, chalcogenides, phosphides, and boride materials, and spin‐related metastable‐phase materials are represented. Case studies on 2D metastable‐phase oxides are provided, followed by examples of different applications related to electrocatalysis, photocatalysis, and thermocatalysis. We complete this book by discussing the current challenges and future perspectives along the concept of metastable‐phase materials.
Qi Shao
College of Chemistry, Chemical Engineering and Materials Science
Soochow University
China
1Introduction of the Metastable‐Phase Materials
Qi Shao1 and Mingwang Shao2
1Soochow University, College of Chemistry, Chemical Engineering and Materials Science, Suzhou, 215123, Jiangsu, China
2Soochow University, Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon‐Based Functional Materials & Devices, Suzhou, 215123, Jiangsu, China
1.1 Introduction
From the point of classical thermodynamics, no metastable‐phase can exist [1]. Yet, when we look around our world, the number of metastable‐phase materials is so huge that it is predominantly larger than that of stable‐phase ones. For simple chemical compounds, the ratio of metastable‐phases to stablephases is not large. However, the number of metastable compounds becomes dramatically large for complex chemicals, such as organic ones and polymers [2]. For biological materials, nearly 100% phases are metastable ones [3]. Therefore, we can say with certainty: The more complex the materials, the larger the number of metastable‐phases.
Such a huge number of metastable‐phase materials will certainly bring out interesting and important properties, which may find wide applications in the energy, material, industry, agriculture, biology, environmental, and catalysis‐related fields [4]. It should be pointed out that in this book the authors have tried to emphasize on classification, synthetic methodology, characterization, and catalytic performance of different metastable‐phase materials.
1.2 What Are Metastable‐Phase Materials?
A metastable‐phase material is the matter located in a state that corresponds to a local minimum in energy separated by a barrier from the state corresponding to the global minimum. Metastable‐phases are in a nonequilibrium state and thus show thermodynamic instability [5]. The energy barrier ensures the metastability and keeps the metastable‐phase materials from transformation to stable states, as shown in Figure 1.1.
Figure 1.1 The schematic of metastable‐phase and stable‐phase. The red ball and the blue ball point to metastable‐phase and stable‐phase, respectively.
Some metastable‐phase materials may exist for a long time, such as diamond, which may exist virtually infinitely at room temperature. However, some only exist for a very short time, such as β‐Sn, which may exist only for a few days at a temperature of −20 °C and then transform to α‐Sn [6].
1.3 The Categories of Metastable‐Phase Materials
Considering the large number of metastable‐phase materials, several classifications for metastable‐phase materials are highly recommended.
From the point of crystallinity, metastable‐phases may be classified as crystalline metastable‐phases, microcrystalline metastable‐phases, quasicrystalline metastable‐phases, and amorphous metastable‐phases.
Microcrystalline metastable‐phase materials, or nanocrystalline metastable‐phase materials, have large surface energy, which is favorable to the stability of metastable‐phases [7]. These materials have numerous grain boundaries and defects, which bring out larger values of hardness, strength, heat capacity, electrical resistivity, and magnetism [8].
Quasicrystalline metastable‐phase materials show lack of transition symmetry [9]. These materials usually have low surface energy, low friction ecoefficiency, but high values of wear resistance, hardness, high‐temperature plasticity, thermal resistance, corrosion resistance [10].
Amorphous metastable‐phase materials have short‐range order and long‐range disorder [11]. They have excellent soft magnetic performance and high values of strength and corrosion resistance [12, 13].
This book will focus on the crystalline metastable‐phase materials only.
As metastable‐phases, together with their corresponding stable‐phases, form polymorphs, we classified polymorphs according to the chemical bonds and the coordination environment.
Figure 1.2 The crystal structures of (a) α‐Ni and (b) β‐Ni.
1.3.1 Different Packing Orders
These polymorphs have the same layers with identical composition, coordination environment, connection mode of coordination. Yet, there are differences in the packing order of these layers.
The typical examples are α‐Ni and β‐Ni (Figure 1.2), where α‐Ni is the stable‐phase, while β‐Ni is a metastable‐phase one. Both of them are coordinated with the number of 12. Each layer of these two materials is composed of the closest packing Ni atoms, with one Ni atom surrounded by six Ni in one layer. Their difference is in the packing order, α‐Ni is packed with the order of ABC and β‐Ni is AB [14]. The ABC packing endows α‐Ni with strong ferromagnetism, while the magnetism of β‐Ni is so weak that it can be ignored [15, 16].
The number of this kind of polymorphs is extraordinarily large because only a small amount of energy is needed to alter the packing order. Both SiC and ZnS have hundreds of polymorphs with different packing orders [17, 18].
1.3.2 Different Connecting Modes
These polymorphs have the same coordination polyhedron but different connection modes of these polyhedra. The typical example is TiO2. Rutile‐, anatase‐, and brookite‐TiO2 have the same TiO6 coordination octahedron (Figure 1.3) [19]. Although their connection mode shares edge and corner together, rutile‐, anatase‐, and brookite‐TiO2 share 2, 4, and 3 edges, respectively, among which rutile‐TiO2 is the most stable material [20].
As the energy to alter connection mode is larger than that for packing order, the number of this kind of polymorphs is less than that of previous ones.
1.3.3 Different Coordination Number
Different coordination number indicates the formation or breaking of chemical bonds, which often involves a large amount of energy [21]. Therefore the number of this kind of polymorphs is small.
Figure 1.3 The crystal structures of (a) rutile‐, (b) anatase‐, and (c) brookite‐TiO2.
Figure 1.4 The crystal structures of (a) α‐ and (b) γ‐Fe.
The typical example of this kind of polymorphs is iron (Fe). The α‐ and γ‐Fe have body‐centered cubic and face‐centered cubic phases (Figure 1.4), with the coordination numbers of 8 and 12, respectively [22].
1.3.4 Different Kinds of Chemical Bonds
There are only a few examples for this kind of polymorphs. For example, α‐ and β‐Sn are formed with covalent bonds and metallic bonds, respectively (Figure 1.5) [23]. Another example is carbon, where graphite has a mixture of covalent bonds and van der Waals bonds, while diamond is composed of pure covalent bonds (Figure 1.6) [24, 25].
Figure 1.5 The crystal structures of (a) α‐ and (b) β‐Sn.
Figure 1.6 The crystal structures of (a) graphite and (b) diamond.
1.3.5 Order and Disorder Polymorphs
Order and disorder polymorphs generally exist in alloys and metallic compounds. At low temperatures, different kinds of atoms were arranged orderly to form crystals with low symmetry; and at high temperature, these atoms occupy the positions disorderly to obtain crystals with high symmetry [26].
For example, FeAl alloy is a simple cube at low temperatures and becomes a body‐centered cube at high temperatures (Figure 1.7) [27, 28].
1.3.6 Molecular Thermal‐Motion‐Related Polymorphs
Temperature also has a significant effect on crystals with ionic groups [29]. As the temperature rises, the thermal vibration of ionic groups becomes so obvious that these groups may rotate freely showing spherical symmetry, leading to the high symmetry of crystal [30]. For example, NaCN and KCN have low symmetry at low temperatures and form rocksalt structure at high temperatures [31].
Figure 1.7 The crystal structures of FeAl alloy at (a) low and (b) high temperatures.
Organic compound C29H60, whose carbon atoms are connected by the chain‐like mode, belongs to the orthorhombic system at low temperatures [32]. As the temperature increases, the molecule rotates around the long axis and has cylindrical symmetry, leading to hexagonal crystal system.
1.3.7 Spin‐Related Polymorphs
The polymorphs have the same in X‐ray diffraction patterns. Yet, neutron diffraction can discover their differences due to the spin variation.
For example, α‐Fe becomes β‐Fe when temperature is over 770 °C [33]. Although both of them are body‐centered cubic phase, the former one is spin‐order and the latter one is spin‐disorder. Another example is the superconductor, YBa2Cu3O7−δ when the temperature is below 90 K. It becomes a common conductor with temperature over 90 K [34].
1.4 The Influence on Polymorphs of Materials
1.4.1 Temperature
In this case, as the temperature rises, the coordination number of crystals decreases and crystal symmetry increases [35]. As shown in Table 1.1, metals Ti, Zr, and Tl are in hexagonal closest packing ordering at low temperatures and become body‐centered cubic ordering at high temperatures [36–38]. In this process, the coordination number decreases from 12 to 8.
1.4.2 Pressure
When increasing the pressure, the coordination number of crystals will increase and the crystal symmetry will decrease.
Table 1.1 The effect of temperature on polymorphs.
Name
Crystal structure at low
T
Coordination number at low
T
Crystal structure at high
T
Coordination number at high
T
CsCl
CsCl
8 : 8
NaCl
6 : 6
RbCl
CsCl
8 : 8
NaCl
6 : 6
Ti
HCP
12
BCC
8
Zr
HCP
12
BCC
8
Tl
HCP
12
BCC
8
CaCO
3
Aragonite
9
Calcite
6
KNO
3
Aragonite
9
Calcite
6
Table 1.2 The effect of pressure on polymorphs.
Name
Crystal structure at low
P
Coordination number at low
p
Crystal structure at high
P
Coordination number at high
P
RbCl
NaCl
6 : 6
CsCl
8 : 8
RbBr
NaCl
6 : 6
CsCl
8 : 8
RbI
NaCl
6 : 6
CsCl
8 : 8
Cs
BCC
8
FCC
12
Fe
BCC
8
FCC
12
GeO
2
Quartz
4 : 2
Rutile
6 : 3
As shown in Table 1.2, metals Cs and Fe are body‐centered cubic phase at ambient pressure and become face‐centered cubic phase with increasing pressure. Their coordination numbers also increase from 8 to 12 [39, 40].
1.4.3 The Stability in Nano‐size Metastable‐Phase Catalysts
The metastable‐phase catalysts may achieve dual improvement in catalytic activity and stability. Let us explain our assertion.
The sizes of catalysts are often in nano‐scale to obtain maximum utilization of catalyst atoms. And metastable‐phase materials may have high catalytic activity due to their high free energy. It is generally believed that the stability of metastable‐phases is the biggest challenge in the development of metastable‐phase catalysts. Yet, in fact, it is not necessarily like that.
Although the stability of the metastable‐phase in bulk is not as good as its corresponding stable‐phase, at the nanoscale, the stability of the metastable‐phase may be higher than that of the stable‐phase. For example, anatase titanium dioxide with a size less than 10 nm is higher than rutile of the same size.
In addition, dimension is also a consideration, as two‐dimensional materials only have van der Waals bonds between layers, resulting in small surface energy. Therefore, two‐dimensional materials are often more stable than their corresponding three‐dimensional stable‐phases. Iridium dioxide in the 1T phase is more stable than iridium dioxide in rutile.
In short, the low dimension and/or small size endow metastable‐phase catalysts with higher catalytic activity and stability than their corresponding stable ones.
1.5 The Wide Applications of Metastable‐Phase Materials
Metastable‐phase materials with novel properties are essential to solving enormous future challenges, such as energy crisis, food safety, resource depletion, and environmental pollution [41].
These applications include catalysts [42], photocatalysts [43], electrocatalysts [44], semiconductors [45], magnets [46], ion conductors [47], superconductors [48], thermoelectrics [49], photoluminescent materials [50], and sensors [51].
1.6 The Criterion for Stable‐Phase and Metastable‐Phase Materials
The following discussion is about the criterion for stable‐phase metals and metastable‐phase metals.
There is always an inequality (1.1), on the basis of the definition of metastable‐phases.
Or
As both the stable‐phase and metastable‐phase are solid, the difference between and is very small.
Therefore, the inequality is often correct.
On the other hand, bond energy, or bond disruption energy, is defined as the standard enthalpy change of the following fission: R − X → R + X, denoted by D0(R − X). And the enthalpy of formation may be approximated as the sum of bond energies.
So, we may obtain:
For a given chemical bond, its bond energy is inversely proportional to bond length [52, 53].
Huggins gave an equation for bond energy and bond length,
where D is bond energy, r bond length, and a and r0 are constant for a given bond.
For both stable‐phase and metastable‐phase, if the nature of their chemical bonds is the same, the following inequality is present, as a rough approximation,
Here, a is a parameter related with the crystal structure. After a broad investigation, . V is the volume of crystal cells and Z is the number of chemical formulas in a crystal cell.
The above equation may be re‐written as:
Furthermore, if the coordination numbers of stable‐phase and metastable‐phase are the same, we may obtain
For example, TiO2 has many crystal structures and the main important ones are rutile, anatase, and brookite. All these three have TiO6 coordination octahedron with various connected modes. Therefore, we may use Eq. (1.3) to determine which one is the stable‐phase. Based on the calculation (Table 1.3), rutile is the stable‐phase while others are metastable‐phases, because the value of for rutile is the smallest.
Table 1.3 The criterion to determine stable‐phase and metastable‐phase for rutile, anatase, and brookite TiO2.
Material
Unit‐cell dimension
r
average
Rutile TiO
2
a = b =
4.60 Å
, c =
2.96 Å;
α = β = γ =
90.00°
3.148
1.961
6.172
Anatase TiO
2
a
=
b
= 3.78 Å,
c =
9.62 Å;
α = β = γ =
90.00°
3.240
1.544°
6.332
Brookite TiO
2
a
=
5.15 Å
,
b
= 5.46 Å
, c
= 9.19
Å; α
=
β
=
γ
= 90.00°
3.182
1.963
6.244
References
1
Alert, R., Tierno, P., and Casademunt, J. (2016). Formation of metastable phases by spinodal decomposition.
Nature Communications
7: 13067.
2
Sasaki, S., Caldes, M.T., Guillot‐Deudon, C. et al. (2021). Design of metastable oxychalcogenide phases by topochemical (de)intercalation of sulfur in La
2
O
2
S
2
.
Nature Communications
12 (1): 3605.
3
Kocevski, V., Valdez, J.A., Derby, B.K. et al. (2023). Predicting and accessing metastable phases.
Materials Advances
4 (4): 1101–1112.
4
Wang, C.X. and Yang, G.W. (2005). Thermodynamics of metastable phase nucleation at the nanoscale.
Materials Science & Engineering R – Reports
49 (6): 157–202.
5
Bechhoefer, J., Löwen, H., and Tuckerman, L.S. (1991). Dynamical mechanism for the formation of metastable phases.
Physical Review Letters
67 (10): 1266–1269.
6
Di Maio, D. and Hunt, C. (2009). Time‐lapse photography of the β‐Sn/α‐Sn allotropic transformation.
Journal of Materials Science: Materials in Electronics
20 (4): 386–391.
7
Li, H.B., Zanella, M., Genovese, A. et al. (2011). Sequential cation exchange in nanocrystals: preservation of crystal phase and formation of metastable phases.
Nano Letters
11 (11): 4964–4970.
8
Ayyub, P., Multani, M., Barma, M. et al. (1988). Size‐induced structural phase transitions and hyperfine properties of microcrystalline Fe
2
O
3
.
Journal of Physics C – Solid State Physics
21 (11): 2229–2245.
9
Urgel, J.I., Ecija, D., Lyu, G.Q. et al. (2016). Quasicrystallinity expressed in two‐dimensional coordination networks.
Nature Chemistry
8 (7): 657–662.
10
Yoshida, T., Itoh, K., Tamura, R., and Takeuchi, S. (2000). Plastic deformation and hardness in Mg‐Zn‐(Y, Ho) icosahedral quasicrystals.
Materials Science and Engineering A – Structural Materials Properties
294: 786–789.
11
Shi, L., Zhang, Y.F., Dong, B.Q. et al. (2013). Amorphous photonic crystals with only short‐range order.
Advanced Materials
25 (37): 5314–5320.
12
Patil, U., Hong, S.H., and Suryanarayana, C. (2005). An unusual phase transformation during mechanical alloying of an Fe‐based bulk metallic glass composition.
Journal of Alloys and Compounds
389 (1‐2): 121–126.
13
Suryanarayana, C. (2019). Mechanical alloying: a novel technique to synthesize advanced materials.
Research
2019: 17.
14
Chandran, M. and Sondhi, S.K. (2011). First‐principle calculation of stacking fault energies in Ni and Ni‐Co alloy.
Journal of Applied Physics
109
(10): 103525.
15
Hossain, M.D., Mayanovic, R.A., Dey, S. et al. (2018). Room‐temperature ferromagnetism in Ni (II)‐chromia based core–shell nanoparticles: experiment and first principles calculations.
Physical Chemistry Chemical Physics
20 (15): 10396–10406.
16
Davar, F., Fereshteh, Z., and Salavati‐Niasari, M. (2009). Nanoparticles Ni and NiO: synthesis, characterization and magnetic properties.
Journal of Alloys and Compounds
476 (1‐2): 797–801.
17
Fang, X.S., Zhai, T.Y., Gautam, U.K. et al. (2011). ZnS nanostructures: from synthesis to applications.
Progress in Materials Science
56 (2): 175–287.
18
Matsunami, H. and Kimoto, T. (1997). Step‐controlled epitaxial growth of SiC: High quality homoepitaxy.
Materials Science & Engineering R – Reports
20 (3): 125–166.
19
Kaplan, R., Erjavec, B., Dražić, G. et al. (2016). Simple synthesis of anatase/rutile/brookite TiO
2
nanocomposite with superior mineralization potential for photocatalytic degradation of water pollutants.
Applied Catalysis B – Environmental
181: 465–474.
20
Gao, C.M., Wei, T., Zhang, Y.Y. et al. (2019). A photoresponsive rutile TiO
2
heterojunction with enhanced electron–hole separation for high‐performance hydrogen evolution.
Advanced Materials
31 (8): 1806596.
21
Wang, L.L., Zhu, C.W., Xu, M.Q. et al. (2021). Boosting activity and stability of metal single‐atom catalysts via regulation of coordination number and local composition.
Journal of the American Chemical Society
143 (45): 18854–18858.
22
He, Y., Li, Y.J., Chen, C.F., and Yu, H.B. (2017). Diffusion coefficient of hydrogen interstitial atom in α‐Fe, γ‐Fe and ɛ‐Fe crystals by first‐principle calculations.
International Journal of Hydrogen Energy
42 (44): 27438–27445.
23
Haq, A.U., Askari, S., McLister, A. et al. (2019). Size‐dependent stability of ultra‐small α‐/β‐phase tin nanocrystals synthesized by microplasma.
Nature Communications
10 (1): 817.
24
Ooi, N., Rairkar, A., and Adams, J.B. (2006). Density functional study of graphite bulk and surface properties.
Carbon
44 (2): 231–242.
25
Erdemir, A. and Martin, J.M. (2018). Superior wear resistance of diamond and DLC coatings.
Current Opinion in Solid State & Materials Science
22 (6): 243–254.
26
Kim, K., Arora, A., Lewis, R.M. III, et al. (2018). Origins of low‐symmetry phases in asymmetric diblock copolymer melts.
Proceedings of the National Academy of Sciences of the United States of America
115 (5): 847–854.
27
Kupka, M. (2006). High temperature strengthening of the FeAl intermetallic phase‐based alloy.
Intermetallics
14 (2): 149–155.
28
Baker, I. and Munroe, P.R. (1997). Mechanical properties of FeAl.
International Materials Reviews
42 (5): 181–205.
29
Liu, Q., Liao, Z.R., and Axinte, D. (2020). Temperature effect on the material removal mechanism of soft‐brittle crystals at nano/micron scale.
International Journal of Machine Tools & Manufacture
159: 103620.
30
Chang, C., Wu, M.H., He, D.S. et al. (2018). 3D charge and 2D phonon transports leading to high out‐of‐plane ZT in n‐type SnSe crystals.
Science
360 (6390): 778–783.
31
Ushkov, A.V. and Grushin, V.V. (2011). Rational catalysis design on the basis of mechanistic understanding: highly efficient Pd‐catalyzed cyanation of aryl bromides with NaCN in recyclable solvents.
Journal of the American Chemical Society
133 (28): 10999–11005.
32
Mare, E.R., O'Neill, H.S.C., Berry, A.J. et al. (2021). Coordination change of Ge
4+
and Ga
3+
in silicate melt with pressure.
Geochimica Et Cosmochimica Acta
303: 184–204.
33
Vershinina, T.N., Bobrikov, I.A., Sumnikov, S.V. et al. (2021). Crystal structure and phase composition evolution during heat treatment of Fe‐45Ga alloy.
Intermetallics
131: 107110.
34
Soderholm, L., Zhang, K., Hinks, D.G. et al. (1987). Incorporation of Pr in YBa
2
Cu
3
O
7
‐δ: electronic effects on superconductivity.
Nature
328 (6131): 604–605.
35
Mary, T.A., Evans, J.S.O., Vogt, T., and Sleight, A.W. (1996). Negative thermal expansion from 0.3 to 1050 Kelvin in ZrW
2
O
8
.
Science
272 (5258): 90–92.
36
Assi, H., Mouchaham, G., Steunou, N. et al. (2017). Titanium coordination compounds: from discrete metal complexes to metal‐organic frameworks.
Chemical Society Reviews
46 (11): 3431–3452.
37
Lv, D.F., Chen, J.Y., Chen, Y.W. et al. (2019). Moisture stability of ethane‐selective Ni (II), Fe (III), Zr (IV)‐based metal‐organic frameworks.
AIChE Journal
65 (8): e16616.
38
Karasev, M.O., Karaseva, I.N., and Pushkin, D.V. (2021). MC
n
(M= Ga, In, Tl) coordination polyhedra in crystal structures.
Russian Journal of Inorganic Chemistry
66: 1669–1681.
39
Xie, Y., Ma, Y.M., Cui, T. et al. (2008). Origin of bcc to fcc phase transition under pressure in alkali metals.
New Journal of Physics
10 (6): 063022.
40
Matsui, M. and Anderson, O.L. (1997). The case for a body‐centered cubic phase (α′) for iron at inner core conditions.
Physics of the Earth and Planetary Interiors
103 (1‐2): 55–62.
41
Therrien, F., Jones, E.B., and Stevanović, V. (2021). Metastable materials discovery in the age of large‐scale computation.
Applied Physics Reviews
8 (3): 031310.
42
Zhang, Z., Zandkarimi, B., and Alexandrova, A.N. (2020). Ensembles of metastable states govern heterogeneous catalysis on dynamic interfaces.
Accounts of Chemical Research
53 (2): 447–458.
43
Zhang, Y.Z., Zhou, W., Tang, Y. et al. (2022). Unravelling unsaturated edge S in amorphous NiS
x
for boosting photocatalytic H
2
evolution of metastable phase CdS confined inside hydrophilic beads.
Applied Catalysis B – Environmental
305: 121055.
44
Wen, W.D., Yan, P., Sun, W.P. et al. (2023). Metastable phase Cu with optimized local electronic state for efficient electrocatalytic production of ammonia from nitrate.
Advanced Functional Materials
33 (6): 2212236.
45
Caskey, C.M., Richards, R.M., Ginley, D.S., and Zakutayev, A. (2014). Thin film synthesis and properties of copper nitride, a metastable semiconductor.
Materials Horizons
1 (4): 424–430.
46
Balasubramanian, B., Zhao, X., Valloppilly, S.R. et al. (2018). Magnetism of new metastable cobalt‐nitride compounds.
Nanoscale
10 (27): 13011–13021.
47
Zhou, L.J., Xu, J.G., Allix, M., and Kuang, X.J. (2020). Development of melilite‐type oxide ion conductors.
Chemical Record
20 (10): 1117–1128.
48
Budden, M., Gebert, T., Buzzi, M. et al. (2007). Evidence for metastable photo‐induced superconductivity in K
3
C
60
.
Nature Physics
17 (5): 611–618.
49
Ikeda, T., Collins, L.A., Ravi, V.A. et al. (2007). Self‐assembled nanometer lamellae of thermoelectric PbTe and Sb
2
Te
3
with epitaxy‐like interfaces.
Chemistry of Materials
19 (4): 763–767.
50
Cao, H.Q., Qiu, X.Q., Luo, B. et al. (2004). Synthesis and room‐temperature ultraviolet photoluminescence properties of zirconia nanowires.
Advanced Functional Materials
14 (3): 243–246.
51
Righettoni, M., Tricoli, A., and Pratsinis, S.E. (2010). Thermally stable, silica‐doped ɛ‐WO
3
for sensing of acetone in the human breath.
Chemistry of Materials
22 (10): 3152–3157.
52
Clark, C.H.D. (1939). Interrelation of dissociation energy, internuclear distance and bond order for carbon‐carbon linkages.
Nature
143 (3628): 800–801.
53
Huggins, M.L. (1953). Atomic radii. IV. Dependence of interatomic distance on bond energy.
Journal of the American Chemical Society
75: 4126–4133.
2Synthetic Methodology
Qi Shao
Soochow University, College of Chemistry, Chemical Engineering and Materials Science, Suzhou, 215123, Jiangsu, China
2.1 Introduction
The synthetic methods are the core of the material field. With the development of new synthetic methodology, various new materials have been successfully obtained, which is the precondition for the research of new properties and also the primary impetus of material science and technology [1].
Synthetic methodology of materials overlaps with other fields, such as theoretical calculation, physics, chemistry, biology, and geology [2]. Its contents include the design of materials, predication of properties, computer simulation, special synthetic technology, and characterization of structure [3]. In the chapter, we mainly discuss the various synthetic technologies for preparing different kinds of metastable‐phase materials.
2.2 The Key for Synthesizing Metastable‐Phase Materials
For the synthetic methodology, the core issues are the design of materials with required structures and properties and the choice of the synthetic routes [4]. In order to obtain the required materials, people should first consider their structures, physical and chemical properties, the thermodynamics and kinetics of the reactions, reaction conditions, and the separation of the products [5]. Especially, much attention should be paid on the improvement and innovation of the synthetic technology [6].
Synthesis of metastable‐phase materials needs large energy consumption as the first premise [7]. It is because metastable‐phase materials have higher energy than the stable ones [8]. For example, high temperature and high pressure ensure large energy consumption in the synthesis of the metastable‐phase diamond; arc discharge supplies vast energy in the preparation of C60[9]. Therefore, the key and major premise for synthesizing metastable materials lies in the input of high energy (Figure 2.1). According to this premise, Shao et al. proposed the alkali‐assisted mechanothermal method to produce new metastable‐phases of IrO2 and RhO2[10]
