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論文題目「Synthesis of Titanium-based Transition Metal Nitride and Oxynitride Nanoparticles by Induction Thermal Plasma 」
Yirong Wang
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論文題目「Synthesis of Titanium-based Transition Metal Nitride and Oxynitride Nanoparticles by Induction Thermal Plasma 」
Yirong Wang
Titanium nitride (TiN) and titanium oxynitride (TiON) are promising ceramic
materials that exhibit high electrical conductivity, superior mechanical
hardness, excellent thermal and chemical stability. The adjustable band
gap and chemical stability of TiN and TiON make them widely used in hard
coatings, fuel cells, supercapacitor electrodes, and visible light responsive
photocatalytic materials. Incorporating transition metals such as Ta, Nb,
Zr, and Cr into the Ti–N or Ti–O–N matrix leads to the formation of titanium-based
transition metal nitrides (Ti–Me–N) and oxynitrides (Ti–Me–O–N), which
further enhance phase stability, electronic modulation, and compositional
flexibility. These multicomponent systems are increasingly attracting attention
for applications in the fields of functional ceramics and energy materials
such as catalysis, energy, optoelectronic devices, optical coatings and
microelectronic devices. Conventional synthesis methods are time-consuming
and complex. This makes it difficult to synthesize titanium oxynitride
on a large scale without introducing impurities. Induction thermal plasmas
achieve extremely high temperatures up to 10,000 K, exhibit high chemical
reactivity, rapid quenching effect (103~106 K/s), electrodeless discharge
and controllable atmosphere. Induction thermal plasmas is particularly
suitable for synthesis and modulation of high-purity nanoparticles. This
dissertation explores the controlled synthesis of Ti–Me–N and Ti–Me–O–N
nanoparticles using induction thermal plasma and systematically investigates
the relationships among precursor composition, thermodynamic parameters,
formation mechanism, and final structural characteristics.
Chapter 1 presents the background and motivation for the study of Ti-Me-N and Ti-Me-O-N nanoparticles. The superiority of inductive thermal plasma in the synthesis of nanoparticles is emphasized. The objective of this dissertation is introduced.
In Chapter 2, ternary titanium niobium nitride (Ti1-xNbxN) nanoparticles were successfully synthesized using metallic Ti and Nb powders with various Nb/(Ti+Nb) molar ratios under Ar–NH3 plasma environment. All samples crystallized in a cubic rock salt structure. Diffraction peak shifts and lattice parameter changes followed Vegard’s law. There was uniform particle morphology and homogeneous elemental distribution across all compositions. The average particle size was consistently around 10–14 nm. Thermodynamic calculations revealed that Nb supersaturated earlier than Ti, which was followed by the rapid condensation of Ti, Nb, and their nitride species.
Chapter 3 extended the investigation to other transition metals. Ternary Ti-Me-N (Me = Ta, Nb, Zr, Cr) nanoparticles were prepared using Ti and Me powders or nitrides with a molar ratio of 1:1 in Ar–NH3 plasma environment. The XRD and TEM analyses confirmed that all of the nanoparticles exhibited a cubic rock salt structure, with an average particle size ranging from 8 to 17 nm. The morphologies were relatively uniform and cubic-shaped, with varying degrees of agglomeration due to high surface energy. Elemental mapping revealed an even distribution of the Ti and Me elements, confirming the formation of solid solutions. In the Ti–Ta–N, Ti–Nb–N, and Ti–Zr–N systems, metals with higher nucleation temperatures and lower saturation ratios (Ta, Nb, and Zr) nucleated earlier than Ti. Nitridation occurs when metal vapors interact with ammonia decomposition products, forming stable Ti-Me-N nanoparticles that condense and solidify.
In Chapter 4, the focus shifted to oxynitride synthesis. Titanium niobium oxynitride (Ti–Nb–O–N) nanoparticles were synthesized with varied Nb and oxygen contents. The XRD results showed that achieving an optimal balance of Nb and O content resulted in the formation of a homogeneous oxynitride phase. However, excess oxygen or niobium caused phase segregation into TiO2, hcp-NbN, or Nb2O5. Lattice parameters expanded with Nb doping and contracted with oxygen incorporation. The oxygen content significantly affected the morphology and particle size. Higher oxygen content resulted in larger cubic structures. The XPS spectra showed a shift from Ti–N and Nb–N bonding to Ti–O and Nb–O bonding as the oxygen content increased. Thermodynamic equilibrium indicated that Nb nucleated first under O-free and lower O2 conditions. However, NbO2 became the initial nucleation phase when the oxygen content was higher.
In Chapter 5, the study was further extended to the synthesis of Ti–Me–O–N (Me = Ta, Nb, Zr, Cr) nanoparticles using micro-sized Ti and Me (Ta, Nb, Cr) or ZrN powders in Ar–O2 and Ar–NH3 plasma environments. Analyses of XRD and HRTEM confirmed the successful formation of crystalline phases with predominantly cubic rock salt structures. The extent of solid solution formation and the emergence of secondary phases were found to depend strongly on the ionic radius and chemical reactivity of the transition metal dopant. Larger metal ions, such as Zr and Nb, led to partial phase separation or oxide enrichment due to lattice distortion or a high affinity for oxygen. Metals with similar or smaller ionic radii such as Ta and Cr facilitated the formation of homogeneous solid solutions. Elemental mapping revealed uniform distribution in most samples, except for the Ti–Zr–O–N sample, in which ZrO2 segregation occurred. The XPS results confirmed the coexistence of Me–N, Me–O, and Me–ON bonds in all systems. Thermodynamic and kinetic analyses revealed the primary nucleation species for the Ti-Ta-O-N, Ti-Nb-O-N, Ti-Zr-O-N, and Ti-Cr-O-N systems to be the oxides TaO2, NbO2, ZrO2, and TiO2, respectively. The formation mechanism was dominated by vapor-phase condensation, followed by oxidation and nitridation, during rapid quenching.
Chapter 6 presents the conclusions of the dissertation and the outlook for future research.
In conclusion, this dissertation successfully demonstrates that induction thermal plasma is a powerful and scalable method for synthesizing high-purity titanium-based transition metal nitride and oxynitride nanoparticles. The synthesis process enables precise control over phase composition, elemental distribution, morphology, and surface chemical states. The findings contribute fundamental insights into vapor-phase nucleation dynamics, thermochemical behavior, and structure–property relationships in multicomponent ceramic systems. The knowledge gained provides valuable guidelines for designing advanced nanomaterials tailored for specific applications in electronics, energy storage, catalysis, and wear-resistant coatings.
Chapter 1 presents the background and motivation for the study of Ti-Me-N and Ti-Me-O-N nanoparticles. The superiority of inductive thermal plasma in the synthesis of nanoparticles is emphasized. The objective of this dissertation is introduced.
In Chapter 2, ternary titanium niobium nitride (Ti1-xNbxN) nanoparticles were successfully synthesized using metallic Ti and Nb powders with various Nb/(Ti+Nb) molar ratios under Ar–NH3 plasma environment. All samples crystallized in a cubic rock salt structure. Diffraction peak shifts and lattice parameter changes followed Vegard’s law. There was uniform particle morphology and homogeneous elemental distribution across all compositions. The average particle size was consistently around 10–14 nm. Thermodynamic calculations revealed that Nb supersaturated earlier than Ti, which was followed by the rapid condensation of Ti, Nb, and their nitride species.
Chapter 3 extended the investigation to other transition metals. Ternary Ti-Me-N (Me = Ta, Nb, Zr, Cr) nanoparticles were prepared using Ti and Me powders or nitrides with a molar ratio of 1:1 in Ar–NH3 plasma environment. The XRD and TEM analyses confirmed that all of the nanoparticles exhibited a cubic rock salt structure, with an average particle size ranging from 8 to 17 nm. The morphologies were relatively uniform and cubic-shaped, with varying degrees of agglomeration due to high surface energy. Elemental mapping revealed an even distribution of the Ti and Me elements, confirming the formation of solid solutions. In the Ti–Ta–N, Ti–Nb–N, and Ti–Zr–N systems, metals with higher nucleation temperatures and lower saturation ratios (Ta, Nb, and Zr) nucleated earlier than Ti. Nitridation occurs when metal vapors interact with ammonia decomposition products, forming stable Ti-Me-N nanoparticles that condense and solidify.
In Chapter 4, the focus shifted to oxynitride synthesis. Titanium niobium oxynitride (Ti–Nb–O–N) nanoparticles were synthesized with varied Nb and oxygen contents. The XRD results showed that achieving an optimal balance of Nb and O content resulted in the formation of a homogeneous oxynitride phase. However, excess oxygen or niobium caused phase segregation into TiO2, hcp-NbN, or Nb2O5. Lattice parameters expanded with Nb doping and contracted with oxygen incorporation. The oxygen content significantly affected the morphology and particle size. Higher oxygen content resulted in larger cubic structures. The XPS spectra showed a shift from Ti–N and Nb–N bonding to Ti–O and Nb–O bonding as the oxygen content increased. Thermodynamic equilibrium indicated that Nb nucleated first under O-free and lower O2 conditions. However, NbO2 became the initial nucleation phase when the oxygen content was higher.
In Chapter 5, the study was further extended to the synthesis of Ti–Me–O–N (Me = Ta, Nb, Zr, Cr) nanoparticles using micro-sized Ti and Me (Ta, Nb, Cr) or ZrN powders in Ar–O2 and Ar–NH3 plasma environments. Analyses of XRD and HRTEM confirmed the successful formation of crystalline phases with predominantly cubic rock salt structures. The extent of solid solution formation and the emergence of secondary phases were found to depend strongly on the ionic radius and chemical reactivity of the transition metal dopant. Larger metal ions, such as Zr and Nb, led to partial phase separation or oxide enrichment due to lattice distortion or a high affinity for oxygen. Metals with similar or smaller ionic radii such as Ta and Cr facilitated the formation of homogeneous solid solutions. Elemental mapping revealed uniform distribution in most samples, except for the Ti–Zr–O–N sample, in which ZrO2 segregation occurred. The XPS results confirmed the coexistence of Me–N, Me–O, and Me–ON bonds in all systems. Thermodynamic and kinetic analyses revealed the primary nucleation species for the Ti-Ta-O-N, Ti-Nb-O-N, Ti-Zr-O-N, and Ti-Cr-O-N systems to be the oxides TaO2, NbO2, ZrO2, and TiO2, respectively. The formation mechanism was dominated by vapor-phase condensation, followed by oxidation and nitridation, during rapid quenching.
Chapter 6 presents the conclusions of the dissertation and the outlook for future research.
In conclusion, this dissertation successfully demonstrates that induction thermal plasma is a powerful and scalable method for synthesizing high-purity titanium-based transition metal nitride and oxynitride nanoparticles. The synthesis process enables precise control over phase composition, elemental distribution, morphology, and surface chemical states. The findings contribute fundamental insights into vapor-phase nucleation dynamics, thermochemical behavior, and structure–property relationships in multicomponent ceramic systems. The knowledge gained provides valuable guidelines for designing advanced nanomaterials tailored for specific applications in electronics, energy storage, catalysis, and wear-resistant coatings.
研究論文
- Yirong Wang, Kaiwen Zhang, Motonori Hirose, Junya Matsuno, Manabu Tanaka, and Takayuki Watanabe: Synthesis of Ternary Titanium-Niobium Nitride Nanoparticles by Induction Thermal Plasma, Japanese Journal of Applied Physics, 63, 09SP04 (2024.9).
- Kaiwen Zhang, Yuta Tanoue, Yirong Wang, Motonori Hirose, Manabu Tanaka, and Takayuki Watanabe: Synthesis of Tantalum Nitride Nanoparticles with Different Nitridation Atmosphere in Induction Thermal Plasma, IEEE Transactions of Plasma Science, 53 (7), p/1772-1779 (2025.7).
- Yirong Wang, Kaiwen Zhang, Manabu Tanaka, and Takayuki Watanabe: Formation Mechanism of Titanium-based Transition Metal Nitride Nanoparticles Synthesized by Radio Frequency Induction Thermal Plasma, Inorganic Chemistry, 64 (45), p.22355-22366 (2025.11).
国際学会
- Kaiwen Zhang, Yuta Tanoue, Manabu Tanaka, and Takayuki Watanabe: Nanoparticle Synthesis of Tantalum Oxynatiride by Induction Thermal Plasma, The 5th International Union of Materials Research Societies International Conference of Young Researchers on Advanced Materials, C-O4-002, p.116 (2022.8.4 Kyushu University).
- Yirong Wang, Kaiwen Zhang, Kohei Yamashita, Manabu Tanaka, and Takayuki Watanabe: Synthesis of Ternary Ti1-xNbxN Nanoparticles by Induction Thermal Plasma, 32nd Materials Reserch Society of Japan, E-O5-018 (2022.12.5 Yokohama, Industry & Trade Center Building).
- Yirong Wang, Kohei Yamashita, Kaiwen Zhang, Manabu Tanaka, and Takayuki Watanabe: Nanoparticle Synthesis of Ternary Titanium Niobium Nitrides by Induction Thermal Plasmas, Proceedings of 25th International Symposium on Plasma Chemistry, POS-7-121 (2023.5.22 Miyako Messe, Kyoto).
- Kaiwen Zhang, Motonori Hirose, Yirong Wang, Junya Matsuho, Manabu Tanaka, and Tlalayuki Watanabe: Synthesis of Tantalum Nitride Nanoparticles by Induction Thermal Plasma, The 51st Internatonal Conference on Plasma Sicence (2024.6.18 Beijin, China).
- Byeyon-Il Min, Yiran Wang, Manabu Tanaka, and Takayuki Watanabe: Synthesis of Garnet-Type Cubic-LLZO Solid-Electrolyte for All-Solidstate Lithium-Ion Batteries via a Combined Process of Induction Thermal Plasma and Sintering, 5th Shanghai - Kyushu - Yeungnam Symposium (2024.11.16 Yeungnam University, Korea).
- Kaiwen Zhang, Yirong Wang, Motonori Hirose, Junya Matsuho, Manabu Tanaka, and Takayuki Watanabe: Formation Mechanism of Heteroatoms-Doped Tantalum Nitride Nanoparticles by Induction Thermal Plasma, The 35th International Symposium on Chemical Engineering, F03 (2024.11.30, Okinawa Prefectural Municipal Autonomy Hall).
- Kaiwen Zhang, Yirong Wang, Motonori Hirose, Manabu Tanaka, and Talayuki Watanabe: Nanoparticle Synthesis of Heteroatoms-Doped Tantalum Nitride Nanoparticles by Induction Thermal Plasma, 25th Workshop on Fine Particle Plasmas, PO-1 (2025.1.16 National Institute for Fusion Sicence).
国内学会
- Han Chen, Yirong Wang, Kaiwen Zhang, 廣瀨基規, 田中学, 渡辺隆行: 高周波熱プラズマを用いた高融点金属酸窒化物ナノ粒子の合成, プラズマ・核融合学会九州・沖縄・山口支部第27回支部大会研究発表論文集, p.75-76, D-2 (2023.12.10 KDDI維新ホール).
- 田中学, 陳翰, 張楷文, 王芸融, 廣瀨基規, 渡辺隆行: 高周波熱プラズマによるタンタル酸窒化物ナノ粒子の合成, 第41回プラズマプロセシング研究会, 24a-3 (2024.1.24 東京工業大学).
