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Lu C, Chen C. Indentation Strengths of Zirconium Diboride: Intrinsic versus Extrinsic Mechanisms. J Phys Chem Lett 2021; 12:2848-2853. [PMID: 33720728 DOI: 10.1021/acs.jpclett.1c00434] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Zirconium diboride (ZrB2) is an important ultra-high-temperature ceramic, which exhibits outstanding mechanical properties and is widely used in extreme environments. Extensive experimental studies, however, have found that synthesized ZrB2 specimens show widely scattered indentation hardness values ranging from 8.7 to 26 GPa. We have performed comprehensive stress-strain calculations of ZrB2 to explore its structural and stress responses and found that ZrB2 possesses an intrinsic indentation strength of 32.7 GPa, which is on par with those of other transition-metal borides that exhibit higher indentation hardness values of ∼30 GPa. This result suggests that large variations in measured hardness are driven by extrinsic factors, and an analysis of available experimental data indicates that the quality of the crystallinity of specimens holds the key to realizing improved hardness corresponding to the predicted intrinsic indentation strength. These findings offer insights into the origin of the previously reported lower hardness values of ZrB2 and raise the prospects of achieving superior strengths in well-crystallized ZrB2 that approach or match those of other ultrahard transition-metal compounds.
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Affiliation(s)
- Cheng Lu
- School of Mathematics and Physics, China University of Geosciences (Wuhan), Wuhan 430074, China
| | - Changfeng Chen
- Department of Physics and Astronomy, University of Nevada, Las Vegas, Las Vegas, Nevada 89154, United States
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Lu C, Gong W, Li Q, Chen C. Elucidating Stress-Strain Relations of ZrB 12 from First-Principles Studies. J Phys Chem Lett 2020; 11:9165-9170. [PMID: 33054239 DOI: 10.1021/acs.jpclett.0c02656] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Transition-metal boron-rich compounds exhibit favorable synthesis conditions and mechanical properties that hold great promise for wide-ranging applications. However, the complex bonding networks of these compounds produce diverse structural and mechanical behaviors that require in-depth studies. A notable case is ZrB12, which has been reported to possess high Vickers hardness comparable to those of ReB2 and WB4. Surprisingly, first-principles calculations of stress-strain relations reveal unexpected low indentation strengths of ZrB12 well below those of ReB2 and WB4. Such contrasting results are reconciled by noting that the additional presence of a boron-rich phase of ZrB50 in the experimental synthesis process likely plays a key role in the extrinsic strengthening. These findings uncover mechanisms for the higher measured strength of ZrB12 and offer insights for elucidating extrinsic hardening phenomena that may exist in other transition-metal compounds.
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Affiliation(s)
- Cheng Lu
- School of Mathematics and Physics, China University of Geosciences (Wuhan), Wuhan 430074, China
| | - Weiguang Gong
- International Center for Computational Method & Software, State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Quan Li
- International Center for Computational Method & Software, State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Changfeng Chen
- Department of Physics and Astronomy, University of Nevada, Las Vegas, Nevada 89154, United States
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Akopov G, Mak WH, Koumoulis D, Yin H, Owens-Baird B, Yeung MT, Muni MH, Lee S, Roh I, Sobell ZC, Diaconescu PL, Mohammadi R, Kovnir K, Kaner RB. Synthesis and Characterization of Single-Phase Metal Dodecaboride Solid Solutions: Zr1–xYxB12 and Zr1–xUxB12. J Am Chem Soc 2019; 141:9047-9062. [DOI: 10.1021/jacs.9b03482] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Georgiy Akopov
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
- Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States
| | - Wai H. Mak
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Dimitrios Koumoulis
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Hang Yin
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Bryan Owens-Baird
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
- Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States
| | - Michael T. Yeung
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Mit H. Muni
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Shannon Lee
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
- Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States
| | - Inwhan Roh
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
- College of Chemistry, University of California, Berkeley, California 94720, United States
| | - Zachary C. Sobell
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Paula L. Diaconescu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Reza Mohammadi
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Kirill Kovnir
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
- Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States
| | - Richard B. Kaner
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
- Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, United States
- California NanoSystems Institute (CNSI), University of California, Los Angeles, California 90095, United States
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Ma S, Bao K, Tao Q, Xu C, Feng X, Zhao X, Ge Y, Zhu P, Cui T. Double-zigzag boron chain-enhanced Vickers hardness and manganese bilayers-induced high d-electron mobility in Mn 3B 4. Phys Chem Chem Phys 2019; 21:2697-2705. [PMID: 30663734 DOI: 10.1039/c8cp05870a] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The D7b-type structure Mn3B4 was fabricated by high-temperature and high-pressure (HPHT) methods. Hardness examination yielded an asymptotic Vickers hardness of 16.3 GPa, which is much higher than that of Mn2B and MnB2. First principle calculations and XPS results demonstrated that double zigzag boron chains form a strong covalent skeletons, which enhances this structure's integrity with high hardness. Considering that the hardensses of MnB and Mn3B4 are higher than those of Mn2B and MnB2, zigzag and double zigzag boron backbones are superior to isolated boron and graphite-like boron layer backbones for achieving higher hardness. This situation also states that a higher boron content is not the sole factor for the higher hardness in the low boron content transition metal borides. Futhermore, the co-presence of metallic manganese bilayers contribute to the high d-electron mobility and generate electrical conductivity and antiferromagnetism in Mn3B4 which provide us with a new structure prototype to design general-purpose high hardness materials.
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Affiliation(s)
- Shuailing Ma
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, 130012, People's Republic of China.
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Akopov G, Roh I, Sobell ZC, Yeung MT, Kaner RB. Investigation of ternary metal dodecaborides (M 1M 2M 3)B 12 (M 1, M 2 and M 3 = Zr, Y, Hf and Gd). Dalton Trans 2018; 47:6683-6691. [PMID: 29666867 DOI: 10.1039/c8dt00563j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Samples of metal borides with a nominal composition of ((M1)(1-x-z)(M2)(x)(M3)(z)) : 20B (M1, M2 and M3 = Zr, Y, Hf and Gd) were prepared by arc-melting and studied for phase composition (using powder X-ray diffraction (PXRD) and energy dispersive X-ray spectroscopy (EDS)) and mechanical properties (Vickers hardness). Ternary metal dodecaboride phases were successfully synthesized for the majority of compositions, including stabilization of two high-pressure (6.5 GPa) phases (cubic-UB12 structure), HfB12 and GdB12, in (Zr1-x-zHfxGdz) : 20B and (Y1-x-zHfxGdz) : 20B nominal alloy compositions. Unit cell refinement for the samples showed solid solution formation in most cases. Vickers hardness measurements indicated that most samples possess enhanced hardness in comparison to their parent phases, with the alloy (Zr0.50Y0.25Gd0.25) : 20B having a hardness of 46.9 ± 2.4 GPa compared to 41.3 ± 1.1 and 41.6 ± 1.3 GPa for alloy compositions of 1.0 Zr : 20B and 1.0 Y : 20B, respectively, at 0.49 N of applied load. Using the data from this manuscript as well as previous work, pseudo-ternary phase diagrams (at a constant boron content) have been constructed.
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Affiliation(s)
- Georgiy Akopov
- Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.
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Akopov G, Roh I, Sobell ZC, Yeung MT, Pangilinan L, Turner CL, Kaner RB. Effects of Variable Boron Concentration on the Properties of Superhard Tungsten Tetraboride. J Am Chem Soc 2017; 139:17120-17127. [PMID: 29140089 DOI: 10.1021/jacs.7b08706] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Tungsten tetraboride is an inexpensive, superhard material easily prepared at ambient pressure. Unfortunately, there are relatively few compounds in existence that crystallize in the same structure as tungsten tetraboride. Furthermore, the lack of data in the tetraboride phase space limits the discovery of any new superhard compounds that also possess high incompressibility and a three-dimensional boron network that withstands shear. Thus, the focus of the work here is to chemically probe the range of thermodynamically stable tetraboride compounds with respect to both the transition metal and the boron content. Tungsten tetraboride alloys with a variable concentration of boron were prepared by arc-melting and investigated for their mechanical properties and thermal stability. The purity and phase composition were confirmed by energy dispersive X-ray spectroscopy and powder X-ray diffraction. For variable boron WBx, it was found that samples prepared with a metal to boron ratio of 1:11.6 to 1:9 have similar hardness values (∼40 GPa at 0.49 N loading) as well as having a similar thermal oxidation temperature of ∼455 °C. A nearly single phase compound was successfully stabilized with tantalum and prepared with a nearly stoichiometric amount of boron (4.5) as W0.668Ta0.332B4.5. Therefore, the cost of production of WB4 can be decreased while maintaining its remarkable properties. Insights from this work will help design future compounds stable in the adaptable tungsten tetraboride structure.
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Affiliation(s)
- Georgiy Akopov
- Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA) , Los Angeles, California 90095, United States
| | - Inwhan Roh
- Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA) , Los Angeles, California 90095, United States
| | - Zachary C Sobell
- Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA) , Los Angeles, California 90095, United States
| | - Michael T Yeung
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Lisa Pangilinan
- Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA) , Los Angeles, California 90095, United States
| | | | - Richard B Kaner
- Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA) , Los Angeles, California 90095, United States.,Department of Materials Science and Engineering, University of California, Los Angeles (UCLA) , Los Angeles, California 90095, United States.,California NanoSystems Institute (CNSI), University of California, Los Angeles (UCLA) , Los Angeles, California 90095, United States
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Akopov G, Yeung MT, Kaner RB. Rediscovering the Crystal Chemistry of Borides. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1604506. [PMID: 28323358 DOI: 10.1002/adma.201604506] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 11/14/2016] [Indexed: 06/06/2023]
Abstract
For decades, borides have been primarily studied as crystallographic oddities. With such a wide variety of structures (a quick survey of the Inorganic Crystal Structure Database counts 1253 entries for binary boron compounds!), it is surprising that the applications of borides have been quite limited despite a great deal of fundamental research. If anything, the rich crystal chemistry found in borides could well provide the right tool for almost any application. The interplay between metals and the boron results in even more varied material's properties, many of which can be tuned via chemistry. Thus, the aim of this review is to reintroduce to the scientific community the developments in boride crystal chemistry over the past 60 years. We tie structures to material properties, and furthermore, elaborate on convenient synthetic routes toward preparing borides.
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Affiliation(s)
- Georgiy Akopov
- Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles, CA, 90095, USA
| | - Michael T Yeung
- Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles, CA, 90095, USA
| | - Richard B Kaner
- Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles, CA, 90095, USA
- Department of Materials Science and Engineering and California NanoSystems Institute, University of California, Los Angeles, CA, 90095, USA
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