We report first-principles predictions of a cage-like polymeric nitrogen phase(cage-N)composed of interlocked N10 clusters stabilized by mixed sp^(2)/sp^(3) hybridization.Under high pressure,cage-N exhibits exceptiona...We report first-principles predictions of a cage-like polymeric nitrogen phase(cage-N)composed of interlocked N10 clusters stabilized by mixed sp^(2)/sp^(3) hybridization.Under high pressure,cage-N exhibits exceptional mechanical performance,including an ideal compressive strength of 343 GPa at a pressure of 300 GPa,~33% higher than that of diamond.This ultrahigh strength arises from the synergistic interplay between its three-dimensional covalent framework and hybridized bonding topology,which enables isotropic stress accommodation and dynamic electronic rearrangement.These results establish cage-N as a promising non-carbon ultrahard material and provide a bonding-driven route toward designing superhard frameworks under extreme conditions.展开更多
The four-decade quest for synthesizing ambient-stable polymeric nitrogen,a promising high-energy-density material,remains an unsolved challenge in materials science.We develop a multi-stage computational strategy empl...The four-decade quest for synthesizing ambient-stable polymeric nitrogen,a promising high-energy-density material,remains an unsolved challenge in materials science.We develop a multi-stage computational strategy employing density functional tight-binding-based rapid screening combined with density functional theory refinement and global structure searching,effectively bridging computational efficiency with quantum accuracy.This integrated approach identifies four novel polymeric nitrogen phases(Fddd,P3221,I4m2,and𝑃P6522)that are thermodynamically stable at ambient pressure.Remarkably,the helical𝑃6522 configuration demonstrates exceptional thermal resilience up to 1500 K,representing a predicted polymeric nitrogen structure that maintains stability under both atmospheric pressure and high-temperature extremes.Our methodology establishes a paradigm-shifting framework for the accelerated discovery of metastable energetic materials,resolving critical bottlenecks in theoretical predictions while providing experimentally actionable targets for polymeric nitrogen synthesis.展开更多
Polymeric nitrogen is a potential high-energy-density material with the advantages of high energy density, easy availability of raw materials, and non-pollution. The design and synthesis of polymeric nitrogen are impo...Polymeric nitrogen is a potential high-energy-density material with the advantages of high energy density, easy availability of raw materials, and non-pollution. The design and synthesis of polymeric nitrogen are important in the research field of energetic materials. The cubic gauche nitrogen was successfully synthesized at high pressure in the diamond anvil cell, which stimulated the theoretical and experimental investigations. To date, several hundred kinds of polymeric nitrogen have been reported. This review introduces the progressive development of polymeric nitrogen with high energy density, the challenges faced by the synthesized polymeric nitrogen under high-pressure,and the importance to improve the stability of polymeric nitrogen at ambient pressure. Furthermore, alternative methods for synthesizing polymeric nitrogen under moderate conditions are also presented. In this field, more efforts are needed to develop strategies for stabilizing more polymeric nitrogen to ambient conditions, especially the stability of free surfaces.展开更多
Since the discoveries of polymeric nitrogen, named cg-N (2004), LP-N (2014), HLP-N (2019), another polymorph named black phosphorus nitrogen (BP-N) was synthesized at high-pressure-high-temperature conditions. The nar...Since the discoveries of polymeric nitrogen, named cg-N (2004), LP-N (2014), HLP-N (2019), another polymorph named black phosphorus nitrogen (BP-N) was synthesized at high-pressure-high-temperature conditions. The narrow existing pressure region and similar synthesized pressure of BP-N compared with cg-N indicate that the stable energy and enthalpy of formation of these two structures are close to each other, which was confirmed by our theoretical calculation. In order to obtain the pressure region of BP-N phase, pure N2 and TiN/Pb + N2 precursors were used for laser-heating high pressure experiments in diamond anvil cell (DAC), and the phase identity was examined by Raman and XRD mapping. BP-N can be synthesized in the pressure range of 130 GPa to 140 GPa with the assistance of heating absorber. With the decrease of the pressure, BP-N can be quenched to ~ 40 GPa. The synthesizing pressure–temperature and the stable pressure region of BP-N are important for further exploration of BP-N and its kinetic and thermal dynamic relationship with other polymeric nitrogen, especially cg-N.展开更多
A high-efficient one-step synthesis of cubic gauche polymeric nitrogen was developed just by thermal treatment of KN3powders.Raman and infrared spectra confirm the formation of cubic gauche polymeric nitrogen.Further ...A high-efficient one-step synthesis of cubic gauche polymeric nitrogen was developed just by thermal treatment of KN3powders.Raman and infrared spectra confirm the formation of cubic gauche polymeric nitrogen.Further thermogravimetric differential scanning calorimeter measurements show that the content of cubic gauche polymeric nitrogen is as high as 1.5 wt%with high thermal stability,which is the highest content value reported so far.展开更多
Polymeric nitrogen materials are the crown of high energy density materials due to their environmental friendliness.Here,we proposed a general strategy to achieve crown-like polymeric nitrogen(cr-N)by combining high-p...Polymeric nitrogen materials are the crown of high energy density materials due to their environmental friendliness.Here,we proposed a general strategy to achieve crown-like polymeric nitrogen(cr-N)by combining high-pressure and chemical exfoliation methods.Using the first-principle structure search,we demonstrated that the cerium(Ce)atoms can effectively open the N≡N bond of N_(2)at a moderate pressure of 25.7 GPa,and then the layered chelate P1-CeN_(8)with the crown-like N_(18) ring is formed via the ligand effect of metallic Ce.Interestingly,when released to ambient conditions,P1-CeN_(8)can still maintain good stability due to robust N–N bonds;meanwhile,the interaction strength between the Ce atoms and N_(18) ring decreases.As a result,Ce atoms can be selectively removed by alkaline anions,and the dynamic progresses are presented,which is similar to the synthesis of MXenes via the alkali intercalation exfoliation method,and then crown-like polymeric nitrogen cr-N is formed.The cr-N is proved to be dynamically,mechanically,and thermally stable at ambient conditions.Moreover,the excellent gravimetric energy density,detonation pressure,and detonation velocity of cr-N make it a significant high-energy density material.This work opens a new general avenue to realize polymeric nitrogen via high-pressure and chemical exfoliation methods.展开更多
Exploring the fundamental building block is essential for constructing functional materials with extended topological configurations.In the polymeric nitrogen system,no fundamental building blocks have been reported s...Exploring the fundamental building block is essential for constructing functional materials with extended topological configurations.In the polymeric nitrogen system,no fundamental building blocks have been reported so far.Here,we successfully synthesize the buckled 1-dimensional(1D)band-shaped and 2-dimensional(2D)layered polymeric nitrogen frameworks with N_(18)ring as a fundamental building block for the first time.Furthermore,the dimensions of the polymeric nitrogen frameworks can be regulated by pressure conditions.Bader charge analyses indicate that the charge transfer from the La atom to the low-order bonded nitrogen atom plays a crucial role in stabilizing these two lowdimensional polymeric frameworks.Both LaN_(16)and LaN_(8)are promising high-energy-density materials(HEDMs).This study reveals that the N_(18)ring can serve as a fundamental building block,analogous to the six-membered ring in carbon-based materials,enabling the construction of novel polymeric nitrogen materials with extended frameworks.展开更多
Polymeric nitrogen has long been pursued as a high-energy density material but is very challenging to synthesize at ambient pressure conditions especially with light element precursors.Using a developed one pot method...Polymeric nitrogen has long been pursued as a high-energy density material but is very challenging to synthesize at ambient pressure conditions especially with light element precursors.Using a developed one pot method,we successfully synthesized the atomic polymeric nitrogen employing lithium azide as a precursor.Raman spectrum measurements detected the emerging vibrational peak at 635 cm-1for the polymerized lithium azide sample,indicating the formation of atomic cubic gauche nitrogen(cg-N)with N–N single bonds.Through systematic investigations,the preparation conditions are optimized to be 180℃with a reaction time of 3 h for obtaining atomic cubic gauche polymeric nitrogen.The one pot method achieves the quantitative synthesis of cg-N at ambient pressure using alkali metal azide as the precursors.It offers a simple way for further scalable synthesis of polymeric atomic nitrogen high energy density materials.展开更多
The search for high energy density materials(HEDMs)in polymeric nitrogen compounds has gained considerable attention.Previous theoretical predictions and experiments have revealed that metal ions can be used to stabil...The search for high energy density materials(HEDMs)in polymeric nitrogen compounds has gained considerable attention.Previous theoretical predictions and experiments have revealed that metal ions can be used to stabilize the pentazolate(N-5)anion.In this work,by employing a machine learning-accelerated crystal structure searching method and first-principles calculations,we found that the new pentazolate salts,CaN(10)and BaN(10),are energetically favorable at high pressures.Phonon dispersion calculations reveal that they are quenchable at ambient pressure.Ab initio molecular dynamics simulations verify their dynamic stability at finite temperature.Bader charge and electron localization function illustrates that alkaline earth atoms serve as electron donors,contributing to the stability of N5 rings.Bonding calculations reveal covalent bonds between nitrogen atoms and weak interactions between N5 rings.Similar to other pentazolate salts,these polymeric nitrides have high energy densities of approximately 2.35 kJ/g for CaN(10)and 1.32 kJ/g for BaN(10).The predictions of CaN(10)and BaN(10)structures indicate that these salts are potential candidates for green nitrogen-rich HEDMs.展开更多
In recent decades,pentazolate salts have gained considerable attention as high energy density materials(HEDMs).Using the machine-learning accelerated structure searching method,we predicted four pentazolate salts stab...In recent decades,pentazolate salts have gained considerable attention as high energy density materials(HEDMs).Using the machine-learning accelerated structure searching method,we predicted four pentazolate salts stabilized with tetravalent metals(Ti-N and Zr-N).Specifically,the ground state MN_(20)(M=Ti,Zr)adopts the space-group P 4/mcc under ambient conditions,transforming into the I-4 phase at higher pressure.Moreover,the I-4-MN_(20)becomes energetically stable at moderate pressure(46.8 GPa for TiN_(20),38.7 GPa for ZrN_(20)).Anharmonic phonon spectrum calculations demonstrate the dynamic stabilities of these MN_(20)phases.Among them,the P 4/mcc phase can be quenched to 0 GPa.Further ab-initio molecular dynamic simulations suggest that the N_(5)rings within these MN_(20)systems can still maintain integrity at finite temperatures.Calculations of the projected crystal orbital Hamilton population and reduced density gradient revealed their covalent and noncovalent interactions,respectively.The aromaticity of the N_(5)ring was investigated by molecular orbital theory.Finally,we predicted that these MN_(20)compounds have very high energy densities and exhibit good detonation velocities and pressures,compared to the HMX explosive.These calculations enrich the family of pentazolate compounds and may also guide future experiments.展开更多
基金supported by the Natural Science Foundation of China(Grant Nos.T2325013,52288102,52090024,12034009,12474004,and 12304036)the National Key R&D Program of China Grant No.2023YFA1610000+1 种基金the Fundamental Research Funds for the Central Universitiesthe Program for Jilin University and Sun Yat-sen University.
文摘We report first-principles predictions of a cage-like polymeric nitrogen phase(cage-N)composed of interlocked N10 clusters stabilized by mixed sp^(2)/sp^(3) hybridization.Under high pressure,cage-N exhibits exceptional mechanical performance,including an ideal compressive strength of 343 GPa at a pressure of 300 GPa,~33% higher than that of diamond.This ultrahigh strength arises from the synergistic interplay between its three-dimensional covalent framework and hybridized bonding topology,which enables isotropic stress accommodation and dynamic electronic rearrangement.These results establish cage-N as a promising non-carbon ultrahard material and provide a bonding-driven route toward designing superhard frameworks under extreme conditions.
基金supported by the National Natural Science Foundation of China(Grant Nos.11974154,and 12304278)the Taishan Scholars Special Funding for Construction Projects(Grant No.tstp20230622)+1 种基金the Natural Science Foundation of Shandong Province(Grant Nos.ZR2022MA004,ZR2023QA127,and ZR2024QA121)the Special Foundation of Yantai for Leading Talents above Provincial Level。
文摘The four-decade quest for synthesizing ambient-stable polymeric nitrogen,a promising high-energy-density material,remains an unsolved challenge in materials science.We develop a multi-stage computational strategy employing density functional tight-binding-based rapid screening combined with density functional theory refinement and global structure searching,effectively bridging computational efficiency with quantum accuracy.This integrated approach identifies four novel polymeric nitrogen phases(Fddd,P3221,I4m2,and𝑃P6522)that are thermodynamically stable at ambient pressure.Remarkably,the helical𝑃6522 configuration demonstrates exceptional thermal resilience up to 1500 K,representing a predicted polymeric nitrogen structure that maintains stability under both atmospheric pressure and high-temperature extremes.Our methodology establishes a paradigm-shifting framework for the accelerated discovery of metastable energetic materials,resolving critical bottlenecks in theoretical predictions while providing experimentally actionable targets for polymeric nitrogen synthesis.
基金supported by the CASHIPS Director’s Fund (Grant No. YZJJ202207-CX)。
文摘Polymeric nitrogen is a potential high-energy-density material with the advantages of high energy density, easy availability of raw materials, and non-pollution. The design and synthesis of polymeric nitrogen are important in the research field of energetic materials. The cubic gauche nitrogen was successfully synthesized at high pressure in the diamond anvil cell, which stimulated the theoretical and experimental investigations. To date, several hundred kinds of polymeric nitrogen have been reported. This review introduces the progressive development of polymeric nitrogen with high energy density, the challenges faced by the synthesized polymeric nitrogen under high-pressure,and the importance to improve the stability of polymeric nitrogen at ambient pressure. Furthermore, alternative methods for synthesizing polymeric nitrogen under moderate conditions are also presented. In this field, more efforts are needed to develop strategies for stabilizing more polymeric nitrogen to ambient conditions, especially the stability of free surfaces.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11904281).
文摘Since the discoveries of polymeric nitrogen, named cg-N (2004), LP-N (2014), HLP-N (2019), another polymorph named black phosphorus nitrogen (BP-N) was synthesized at high-pressure-high-temperature conditions. The narrow existing pressure region and similar synthesized pressure of BP-N compared with cg-N indicate that the stable energy and enthalpy of formation of these two structures are close to each other, which was confirmed by our theoretical calculation. In order to obtain the pressure region of BP-N phase, pure N2 and TiN/Pb + N2 precursors were used for laser-heating high pressure experiments in diamond anvil cell (DAC), and the phase identity was examined by Raman and XRD mapping. BP-N can be synthesized in the pressure range of 130 GPa to 140 GPa with the assistance of heating absorber. With the decrease of the pressure, BP-N can be quenched to ~ 40 GPa. The synthesizing pressure–temperature and the stable pressure region of BP-N are important for further exploration of BP-N and its kinetic and thermal dynamic relationship with other polymeric nitrogen, especially cg-N.
基金Project supported by the CASHIPS Director’s Fund(Grant Nos.YZJJ202207-CX,YZJJ202308-TS,YZJJGGZX-2022-01)。
文摘A high-efficient one-step synthesis of cubic gauche polymeric nitrogen was developed just by thermal treatment of KN3powders.Raman and infrared spectra confirm the formation of cubic gauche polymeric nitrogen.Further thermogravimetric differential scanning calorimeter measurements show that the content of cubic gauche polymeric nitrogen is as high as 1.5 wt%with high thermal stability,which is the highest content value reported so far.
基金supported by the National Key R&D Program of China(2023YFA1406200)the National Natural Science Foundation of China(12174143,U23A20561)+1 种基金the Higher Educational Youth Innovation Science and Technology Program Shandong Province(2022KJ183)the Natural Science Foundation of Shandong Province(ZR2023MA016)。
文摘Polymeric nitrogen materials are the crown of high energy density materials due to their environmental friendliness.Here,we proposed a general strategy to achieve crown-like polymeric nitrogen(cr-N)by combining high-pressure and chemical exfoliation methods.Using the first-principle structure search,we demonstrated that the cerium(Ce)atoms can effectively open the N≡N bond of N_(2)at a moderate pressure of 25.7 GPa,and then the layered chelate P1-CeN_(8)with the crown-like N_(18) ring is formed via the ligand effect of metallic Ce.Interestingly,when released to ambient conditions,P1-CeN_(8)can still maintain good stability due to robust N–N bonds;meanwhile,the interaction strength between the Ce atoms and N_(18) ring decreases.As a result,Ce atoms can be selectively removed by alkaline anions,and the dynamic progresses are presented,which is similar to the synthesis of MXenes via the alkali intercalation exfoliation method,and then crown-like polymeric nitrogen cr-N is formed.The cr-N is proved to be dynamically,mechanically,and thermally stable at ambient conditions.Moreover,the excellent gravimetric energy density,detonation pressure,and detonation velocity of cr-N make it a significant high-energy density material.This work opens a new general avenue to realize polymeric nitrogen via high-pressure and chemical exfoliation methods.
基金supported by the National Key R&D Program of China(2023YFA1406200)the National Natural Science Foundation of China(NSFC)(12174143,12404014)+1 种基金the Basic Science Center Project of NSFC(52388201)the China Postdoctoral Science Foundation funded project(2023M741352).
文摘Exploring the fundamental building block is essential for constructing functional materials with extended topological configurations.In the polymeric nitrogen system,no fundamental building blocks have been reported so far.Here,we successfully synthesize the buckled 1-dimensional(1D)band-shaped and 2-dimensional(2D)layered polymeric nitrogen frameworks with N_(18)ring as a fundamental building block for the first time.Furthermore,the dimensions of the polymeric nitrogen frameworks can be regulated by pressure conditions.Bader charge analyses indicate that the charge transfer from the La atom to the low-order bonded nitrogen atom plays a crucial role in stabilizing these two lowdimensional polymeric frameworks.Both LaN_(16)and LaN_(8)are promising high-energy-density materials(HEDMs).This study reveals that the N_(18)ring can serve as a fundamental building block,analogous to the six-membered ring in carbon-based materials,enabling the construction of novel polymeric nitrogen materials with extended frameworks.
基金supported by the National Key R&D Program of China(Grant No.2023YFA1406000)the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-052).
文摘Polymeric nitrogen has long been pursued as a high-energy density material but is very challenging to synthesize at ambient pressure conditions especially with light element precursors.Using a developed one pot method,we successfully synthesized the atomic polymeric nitrogen employing lithium azide as a precursor.Raman spectrum measurements detected the emerging vibrational peak at 635 cm-1for the polymerized lithium azide sample,indicating the formation of atomic cubic gauche nitrogen(cg-N)with N–N single bonds.Through systematic investigations,the preparation conditions are optimized to be 180℃with a reaction time of 3 h for obtaining atomic cubic gauche polymeric nitrogen.The one pot method achieves the quantitative synthesis of cg-N at ambient pressure using alkali metal azide as the precursors.It offers a simple way for further scalable synthesis of polymeric atomic nitrogen high energy density materials.
基金financial support from the National Key R&D Program of China(Grant No.2016YFA0300404)the National Natural Science Foundation of China(Grant Nos.11974162,and 11834006)+1 种基金the Fundamental Research Funds for the Central Universitiesfinancial support from the Project funded by China Postdoctoral Science Foundation(Grant No.2019M651767)。
文摘The search for high energy density materials(HEDMs)in polymeric nitrogen compounds has gained considerable attention.Previous theoretical predictions and experiments have revealed that metal ions can be used to stabilize the pentazolate(N-5)anion.In this work,by employing a machine learning-accelerated crystal structure searching method and first-principles calculations,we found that the new pentazolate salts,CaN(10)and BaN(10),are energetically favorable at high pressures.Phonon dispersion calculations reveal that they are quenchable at ambient pressure.Ab initio molecular dynamics simulations verify their dynamic stability at finite temperature.Bader charge and electron localization function illustrates that alkaline earth atoms serve as electron donors,contributing to the stability of N5 rings.Bonding calculations reveal covalent bonds between nitrogen atoms and weak interactions between N5 rings.Similar to other pentazolate salts,these polymeric nitrides have high energy densities of approximately 2.35 kJ/g for CaN(10)and 1.32 kJ/g for BaN(10).The predictions of CaN(10)and BaN(10)structures indicate that these salts are potential candidates for green nitrogen-rich HEDMs.
基金J.S.gratefully acknowledges the financial support from the National Natural Science Foundation of China(12125404,11974162,11834006)the Fundamental Research Funds for the Central Universities.K.X.acknowledges the National Natural Science Foundation of China under 12004185+2 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China under 20KJB140016the Scientific Research Start-up Funds of Nanjing Forestry University(163101110)the financial support from the Project funded by China Postdoctoral Science Foundation(2019M651767).
文摘In recent decades,pentazolate salts have gained considerable attention as high energy density materials(HEDMs).Using the machine-learning accelerated structure searching method,we predicted four pentazolate salts stabilized with tetravalent metals(Ti-N and Zr-N).Specifically,the ground state MN_(20)(M=Ti,Zr)adopts the space-group P 4/mcc under ambient conditions,transforming into the I-4 phase at higher pressure.Moreover,the I-4-MN_(20)becomes energetically stable at moderate pressure(46.8 GPa for TiN_(20),38.7 GPa for ZrN_(20)).Anharmonic phonon spectrum calculations demonstrate the dynamic stabilities of these MN_(20)phases.Among them,the P 4/mcc phase can be quenched to 0 GPa.Further ab-initio molecular dynamic simulations suggest that the N_(5)rings within these MN_(20)systems can still maintain integrity at finite temperatures.Calculations of the projected crystal orbital Hamilton population and reduced density gradient revealed their covalent and noncovalent interactions,respectively.The aromaticity of the N_(5)ring was investigated by molecular orbital theory.Finally,we predicted that these MN_(20)compounds have very high energy densities and exhibit good detonation velocities and pressures,compared to the HMX explosive.These calculations enrich the family of pentazolate compounds and may also guide future experiments.
