{"title":"静水压力诱导的氧化铁纳米颗粒可逆相变。","authors":"Arkaprava Das, Anumeet Kaur and Parwinder Kaur","doi":"10.1039/D4NR01443J","DOIUrl":null,"url":null,"abstract":"<p >We report hydrostatic pressure-induced reversible phase transformation in maghemite γ-Fe<small><sub>2</sub></small>O<small><sub>3</sub></small> nanoparticles (cubic → tetragonal → cubic) using an <em>in situ</em> diamond anvil cell (DAC) technique. Thermal arc plasma-synthesized nanoparticles, particularly in a He gas medium, exhibit the reversible phase transformation under pressure ranging from 0 to 2.58 GPa. Rietveld refinement reflects that cubic to tetragonal maghemite phase transformation coexists with a cubic metallic Fe phase at 0.55 GPa pressure. The generation of two new superlattice reflections at 6.93° and 8.11°, respectively, reflects the phase transformation. The presence of a core–shell-type nanostructure observed from transmission electron microscopy micrographs is found to exhibit a spin glass shell-type behavior. This triggers pressure-induced fluctuating magnetization and interparticle interaction-induced surface anisotropy and spin disorder with broken bonds, translational symmetry, and incomplete coordination. This leads to overcoming the nucleation barrier at the surface, subsequently denser nucleation sites and increased nucleation probability. This further leads to an atomic rearrangement and tetragonality in the maghemite phase. Furthermore, with increasing pressure, the reversible structural change, <em>i.e.</em> from the tetragonal to cubic maghemite phase, has been explained in the light of the “internal stress model”. The grains are again forced back to the cubic phase <em>via</em> generation of uniform compression along the <em>c</em>-axis and tension along the <em>a</em> and <em>b</em> axes. The spin glass behavior of the core–shell nanostructure along with the “internal stress model” explain the whole reversible phase transformation phenomenon in the γ-Fe<small><sub>2</sub></small>O<small><sub>3</sub></small> phase.</p>","PeriodicalId":92,"journal":{"name":"Nanoscale","volume":null,"pages":null},"PeriodicalIF":5.8000,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Hydrostatic pressure-induced reversible phase transformation in iron oxide nanoparticles†\",\"authors\":\"Arkaprava Das, Anumeet Kaur and Parwinder Kaur\",\"doi\":\"10.1039/D4NR01443J\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p >We report hydrostatic pressure-induced reversible phase transformation in maghemite γ-Fe<small><sub>2</sub></small>O<small><sub>3</sub></small> nanoparticles (cubic → tetragonal → cubic) using an <em>in situ</em> diamond anvil cell (DAC) technique. Thermal arc plasma-synthesized nanoparticles, particularly in a He gas medium, exhibit the reversible phase transformation under pressure ranging from 0 to 2.58 GPa. Rietveld refinement reflects that cubic to tetragonal maghemite phase transformation coexists with a cubic metallic Fe phase at 0.55 GPa pressure. The generation of two new superlattice reflections at 6.93° and 8.11°, respectively, reflects the phase transformation. The presence of a core–shell-type nanostructure observed from transmission electron microscopy micrographs is found to exhibit a spin glass shell-type behavior. This triggers pressure-induced fluctuating magnetization and interparticle interaction-induced surface anisotropy and spin disorder with broken bonds, translational symmetry, and incomplete coordination. This leads to overcoming the nucleation barrier at the surface, subsequently denser nucleation sites and increased nucleation probability. This further leads to an atomic rearrangement and tetragonality in the maghemite phase. Furthermore, with increasing pressure, the reversible structural change, <em>i.e.</em> from the tetragonal to cubic maghemite phase, has been explained in the light of the “internal stress model”. The grains are again forced back to the cubic phase <em>via</em> generation of uniform compression along the <em>c</em>-axis and tension along the <em>a</em> and <em>b</em> axes. The spin glass behavior of the core–shell nanostructure along with the “internal stress model” explain the whole reversible phase transformation phenomenon in the γ-Fe<small><sub>2</sub></small>O<small><sub>3</sub></small> phase.</p>\",\"PeriodicalId\":92,\"journal\":{\"name\":\"Nanoscale\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":5.8000,\"publicationDate\":\"2024-06-18\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Nanoscale\",\"FirstCategoryId\":\"88\",\"ListUrlMain\":\"https://pubs.rsc.org/en/content/articlelanding/2024/nr/d4nr01443j\",\"RegionNum\":3,\"RegionCategory\":\"材料科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CHEMISTRY, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Nanoscale","FirstCategoryId":"88","ListUrlMain":"https://pubs.rsc.org/en/content/articlelanding/2024/nr/d4nr01443j","RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
摘要
我们利用原位金刚石砧室(DAC)技术报告了静水压力诱导的磁铁矿γ-Fe2O3 纳米粒子(立方→四方→立方)的可逆相变。热弧等离子体合成的纳米粒子,尤其是在 He 气体介质中,在 0 至 2.58 GPa 的压力下表现出可逆相变。Rietveld 精炼反映出,在 0.55 GPa 压力下,立方到四方的方镁石相变与立方金属铁相共存。分别在 6.93° 和 8.11° 处产生的两个新的超晶格反射反映了相变。从透射电子显微镜显微照片中观察到的核壳型纳米结构表现出一种自旋玻璃壳型行为。这引发了压力诱导的波动磁化和粒子间相互作用诱导的表面各向异性,以及断键、平移对称和不完全配位的自旋无序。这将导致克服表面的成核障碍,从而增加成核点的密度和成核概率。这进一步导致了方镁石相中的原子重排和四方性。此外,根据 "内应力模型 "的解释,随着压力的增加,结构会发生可逆变化,即从四方方镁石相变为立方方镁石相。通过沿 c 轴产生的均匀压缩和沿 a 轴和 b 轴产生的拉伸,晶粒再次被迫回到立方相。核壳纳米结构的自旋玻璃行为和 "内应力模型 "解释了 γ-Fe2O3 相的整个可逆相变现象。
Hydrostatic pressure-induced reversible phase transformation in iron oxide nanoparticles†
We report hydrostatic pressure-induced reversible phase transformation in maghemite γ-Fe2O3 nanoparticles (cubic → tetragonal → cubic) using an in situ diamond anvil cell (DAC) technique. Thermal arc plasma-synthesized nanoparticles, particularly in a He gas medium, exhibit the reversible phase transformation under pressure ranging from 0 to 2.58 GPa. Rietveld refinement reflects that cubic to tetragonal maghemite phase transformation coexists with a cubic metallic Fe phase at 0.55 GPa pressure. The generation of two new superlattice reflections at 6.93° and 8.11°, respectively, reflects the phase transformation. The presence of a core–shell-type nanostructure observed from transmission electron microscopy micrographs is found to exhibit a spin glass shell-type behavior. This triggers pressure-induced fluctuating magnetization and interparticle interaction-induced surface anisotropy and spin disorder with broken bonds, translational symmetry, and incomplete coordination. This leads to overcoming the nucleation barrier at the surface, subsequently denser nucleation sites and increased nucleation probability. This further leads to an atomic rearrangement and tetragonality in the maghemite phase. Furthermore, with increasing pressure, the reversible structural change, i.e. from the tetragonal to cubic maghemite phase, has been explained in the light of the “internal stress model”. The grains are again forced back to the cubic phase via generation of uniform compression along the c-axis and tension along the a and b axes. The spin glass behavior of the core–shell nanostructure along with the “internal stress model” explain the whole reversible phase transformation phenomenon in the γ-Fe2O3 phase.
期刊介绍:
Nanoscale is a high-impact international journal, publishing high-quality research across nanoscience and nanotechnology. Nanoscale publishes a full mix of research articles on experimental and theoretical work, including reviews, communications, and full papers.Highly interdisciplinary, this journal appeals to scientists, researchers and professionals interested in nanoscience and nanotechnology, quantum materials and quantum technology, including the areas of physics, chemistry, biology, medicine, materials, energy/environment, information technology, detection science, healthcare and drug discovery, and electronics.