尖晶石材料 Co3.34V2.58O8 之晶體結構與磁性研究;Crystal Structure and Magnetic Properties of the Spinel Compound Co3.34V2.58O8

Please use this identifier to cite or link to this item: https://ir.lib.ncu.edu.tw/handle/987654321/99311

Title:	尖晶石材料 Co3.34V2.58O8 之晶體結構與磁性研究;Crystal Structure and Magnetic Properties of the Spinel Compound Co3.34V2.58O8
Authors:	臧承霆;Zang, Chung-TIng
Contributors:	物理學系
Keywords:	Co3V3O8;尖晶石材料;亞鐵磁有序結構;Co3V3O8;Spinel Materials;Ferrimagnetic Ordered structure
Date:	2026-01-19
Issue Date:	2026-03-06 18:36:01 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究透過水熱法及高溫固態反應法兩種合成反應法製備，成功合成了尖晶石材料Co3V3O8，經分析後樣品的晶體結構屬於四方晶系( Tetragonal )，對應空間群為I 41 /a m d。在高解析度X光粉末繞射實驗中初步判定樣品為純相，然後由中子粉末繞射的數據來分析鈷原子( Co )佔有率後，將結果帶入 X 光繞射實驗中分析其他原子的佔有率，最終得到樣品佔有率比例為 Co3.34V2.58O8，並分析樣品的晶體結構特性。 X光吸收光譜分析顯示，鈷原子的平均化學價為+2.3 v. u.，釩原子的平均化學價為 +3.5 v. u.，並且變溫吸收光譜中顯示該樣品中的原子並沒有隨著溫度而有電荷轉移的現象產生。 M–H curve 顯示在4 K時出現明顯的磁滯現象，隨溫度升高，磁滯面積與磁能積逐漸減小，並於200 K時趨近於零。磁化率量測結果依據Curie–Weiss定律擬合，得到尼爾溫度 TN = 305 K，顯示該材料為亞鐵磁性物質。變溫中子繞射分析顯示，在5 K時，Co3.34V2.58O8呈現I 41 / a m′ d′空間群的亞鐵磁結構。其中，A位與B位的磁矩分別沿c軸排列，大小約為3.09 μB /atom 與1.26 μB /atom。隨著溫度升高，總磁矩逐漸下降，並在165 K之後磁矩幾乎為 0 μB /atom，導致磁結構轉變為canted antiferromagnetic ordering。此外，非彈性中子散射實驗未觀察到明顯的非彈性散射峰，顯示該樣品中不存在可解析的磁激子激發。;In this study, spinel-type Co3V3O8 was successfully synthesized using two preparation methods: the hydrothermal method and the high-temperature solid-state reaction method. Structural analysis revealed that the crystal structure belongs to the tetragonal system with the space group I4₁/amd. High-resolution X-ray powder diffraction measurements initially confirmed that the samples are single-phase. Subsequently, the cobalt (Co) site occupancy was determined from neutron powder diffraction data, where magnetic scattering is absent. These results were then incorporated into the X-ray diffraction refinements to determine the occupancies of the remaining atomic sites. The final refined composition was determined to be Co3.34V2.58O8, and the structural characteristics of the sample were systematically analyzed. X-ray absorption spectroscopy analysis indicates that the average oxidation state of Co is +2.3 v.u., while that of V is +3.5 v.u. Variable-temperature X-ray absorption spectra further reveal that no charge transfer occurs among the constituent atoms as a function of temperature. Magnetization (M–H) measurements show a clear hysteresis behavior at 4 K. With increasing temperature, both the hysteresis loop area and the magnetic energy product gradually decrease and approach zero at approximately 200 K. Magnetic susceptibility data fitted using the Curie–Weiss law yield a Néel temperature of Tₙ = 305 K, indicating that the material exhibits antiferromagnetic behavior. Variable-temperature neutron diffraction measurements demonstrate that at 5 K, Co3.34V2.58O8 adopts an antiferromagnetic structure described by the magnetic space group I4₁/a m′d′. The magnetic moments at the A and B sites are aligned along the caxis, with magnitudes of approximately 3.09 μB /atom and 1.26 μB/atom, respectively. As the temperature increases, the total magnetic moment gradually decreases and becomes nearly zero above 165 K, accompanied by a magnetic structure transition to a canted antiferromagnetic ordering. Furthermore, inelastic neutron scattering experiments do not reveal any discernible inelastic scattering peaks,indicating the absence of resolvable magnon excitations in this material.
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

Files in This Item:

File	Description	Size	Format
index.html		0Kb	HTML	76	View/Open

社群 sharing

Loading...