Xiang Jin , Huaijin Ma , Qi Li , Jiawei Xu , Hongwei Zhu , Ru Xing , Jianjun Zhao , O. Tegus , Jiaohong Huang
{"title":"高压热处理法制备La0.65Ca0.35-xBaxMnO3(x=0,0.1,0.2,0.3)的磁热效应及临界行为研究","authors":"Xiang Jin , Huaijin Ma , Qi Li , Jiawei Xu , Hongwei Zhu , Ru Xing , Jianjun Zhao , O. Tegus , Jiaohong Huang","doi":"10.1016/j.jallcom.2025.178704","DOIUrl":null,"url":null,"abstract":"<div><div>In this study, a series of polycrystalline La<sub>0.65</sub>Ca<sub>0.35-<em>x</em></sub>Ba<sub><em>x</em></sub>MnO<sub>3</sub>(<em>x</em> = 0,0.1,0.2,0.3) samples were synthesized through high-pressure heat treatment processing. Their magnetic properties, magnetocaloric effects, and critical behaviors associated with phase transitions were investigated. The substitution of Ba<sup>2+</sup> for Ca<sup>2+</sup> resulted in lattice expansion, which in turn increased the Mn-O-Mn bond angle and enhanced the double-exchange interaction within the system. It was revealed by experimental magnetic studies and Density functional theory calculations that the magnetic interactions, dominated by Mn-3d in the ferromagnetic ground state, were strengthened, leading to an increase in the Curie temperature from 219 K (<em>x</em> = 0) to 249 K (<em>x</em> = 0.1), 272 K (<em>x</em> = 0.2) and 300 K (<em>x</em> = 0.3). Under a magnetic field of 7 T, the maximum magnetic entropy change was found to be 4.47 J·kg<sup>−1</sup>·K<sup>−1</sup> (<em>x</em> = 0), 4.25 J·kg<sup>−1</sup>·K<sup>−1</sup> (<em>x</em> = 0.1), 3.60 J·kg<sup>−1</sup>·K<sup>−1</sup> (<em>x</em> = 0.2) and 3.28 J·kg<sup>−1</sup>·K<sup>−1</sup> (<em>x</em> = 0.3), respectively. Notably, compared to solid-state reaction method samples, the refrigerating temperature range broadened by 131.25 %, 57.44 %, and 47.45 % for x = 0, 0.1, and 0.2, respectively, using high-pressure heat treatment. Additionally, the x = 0.1 sample exhibited a first-to-second-order phase transition. Analysis of Arrott plots confirmed the first-order phase transition in the parent sample and the second-order phase transition in the doped samples. Furthermore, the Modified Arrott plot, Kouver-Fisher, and local exponent methods revealed that, as the Ba content increased, the critical exponents <em>β</em>, <em>γ</em>, and <em>δ</em> of the samples with second-order phase transition characteristics (doped samples) approached 0.5, 1.0, and 0.667, respectively. The introduction of Ba was found to facilitate the establishment of a second-order phase transition pattern that is more consistent with the mean-field theory model.</div></div>","PeriodicalId":344,"journal":{"name":"Journal of Alloys and Compounds","volume":"1014 ","pages":"Article 178704"},"PeriodicalIF":6.3000,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Investigation into magnetocaloric effects and critical behavior of La0.65Ca0.35-xBaxMnO3(x = 0,0.1,0.2,0.3) prepared by high-pressure heat treatment\",\"authors\":\"Xiang Jin , Huaijin Ma , Qi Li , Jiawei Xu , Hongwei Zhu , Ru Xing , Jianjun Zhao , O. Tegus , Jiaohong Huang\",\"doi\":\"10.1016/j.jallcom.2025.178704\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>In this study, a series of polycrystalline La<sub>0.65</sub>Ca<sub>0.35-<em>x</em></sub>Ba<sub><em>x</em></sub>MnO<sub>3</sub>(<em>x</em> = 0,0.1,0.2,0.3) samples were synthesized through high-pressure heat treatment processing. Their magnetic properties, magnetocaloric effects, and critical behaviors associated with phase transitions were investigated. The substitution of Ba<sup>2+</sup> for Ca<sup>2+</sup> resulted in lattice expansion, which in turn increased the Mn-O-Mn bond angle and enhanced the double-exchange interaction within the system. It was revealed by experimental magnetic studies and Density functional theory calculations that the magnetic interactions, dominated by Mn-3d in the ferromagnetic ground state, were strengthened, leading to an increase in the Curie temperature from 219 K (<em>x</em> = 0) to 249 K (<em>x</em> = 0.1), 272 K (<em>x</em> = 0.2) and 300 K (<em>x</em> = 0.3). Under a magnetic field of 7 T, the maximum magnetic entropy change was found to be 4.47 J·kg<sup>−1</sup>·K<sup>−1</sup> (<em>x</em> = 0), 4.25 J·kg<sup>−1</sup>·K<sup>−1</sup> (<em>x</em> = 0.1), 3.60 J·kg<sup>−1</sup>·K<sup>−1</sup> (<em>x</em> = 0.2) and 3.28 J·kg<sup>−1</sup>·K<sup>−1</sup> (<em>x</em> = 0.3), respectively. Notably, compared to solid-state reaction method samples, the refrigerating temperature range broadened by 131.25 %, 57.44 %, and 47.45 % for x = 0, 0.1, and 0.2, respectively, using high-pressure heat treatment. Additionally, the x = 0.1 sample exhibited a first-to-second-order phase transition. Analysis of Arrott plots confirmed the first-order phase transition in the parent sample and the second-order phase transition in the doped samples. Furthermore, the Modified Arrott plot, Kouver-Fisher, and local exponent methods revealed that, as the Ba content increased, the critical exponents <em>β</em>, <em>γ</em>, and <em>δ</em> of the samples with second-order phase transition characteristics (doped samples) approached 0.5, 1.0, and 0.667, respectively. The introduction of Ba was found to facilitate the establishment of a second-order phase transition pattern that is more consistent with the mean-field theory model.</div></div>\",\"PeriodicalId\":344,\"journal\":{\"name\":\"Journal of Alloys and Compounds\",\"volume\":\"1014 \",\"pages\":\"Article 178704\"},\"PeriodicalIF\":6.3000,\"publicationDate\":\"2025-02-05\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Alloys and Compounds\",\"FirstCategoryId\":\"88\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0925838825002622\",\"RegionNum\":2,\"RegionCategory\":\"材料科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"CHEMISTRY, PHYSICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Alloys and Compounds","FirstCategoryId":"88","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0925838825002622","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
摘要
本研究通过高压热处理工艺合成了一系列La0.65Ca0.35-xBaxMnO3(x=0,0.1,0.2,0.3)多晶样品。研究了它们的磁性能、磁热效应和与相变相关的临界行为。Ba2+取代Ca2+导致晶格扩展,从而增加了Mn-O-Mn键角,增强了体系内的双交换相互作用。实验磁学研究和密度泛函数理论计算表明,在铁磁基态中以Mn-3d为主的磁相互作用增强,导致居里温度从219 K (x=0)上升到249 K (x=0.1)、272 K (x=0.2)和300 K (x=0.3)。在7 T磁场下,最大磁熵变化分别为4.47 J·kg-1·K-1 (x=0)、4.25 J·kg-1·K-1 (x=0.1)、3.60 J·kg-1·K-1 (x=0.2)和3.28 J·kg-1·K-1 (x=0.3)。值得注意的是,与固相反应法样品相比,当x=0、0.1和0.2时,高压热处理的制冷温度范围分别扩大了131.25%、57.44%和47.45%。此外,x=0.1样品表现出一阶到二阶的相变。Arrott图分析证实了母体样品的一级相变和掺杂样品的二级相变。此外,修正Arrott图、Kouver-Fisher和局部指数方法表明,随着Ba含量的增加,具有二级相变特征的样品(掺杂样品)的临界指数β、γ和δ分别接近0.5、1.0和0.667。发现Ba的引入有助于建立更符合平均场理论模型的二阶相变模式。
Investigation into magnetocaloric effects and critical behavior of La0.65Ca0.35-xBaxMnO3(x = 0,0.1,0.2,0.3) prepared by high-pressure heat treatment
In this study, a series of polycrystalline La0.65Ca0.35-xBaxMnO3(x = 0,0.1,0.2,0.3) samples were synthesized through high-pressure heat treatment processing. Their magnetic properties, magnetocaloric effects, and critical behaviors associated with phase transitions were investigated. The substitution of Ba2+ for Ca2+ resulted in lattice expansion, which in turn increased the Mn-O-Mn bond angle and enhanced the double-exchange interaction within the system. It was revealed by experimental magnetic studies and Density functional theory calculations that the magnetic interactions, dominated by Mn-3d in the ferromagnetic ground state, were strengthened, leading to an increase in the Curie temperature from 219 K (x = 0) to 249 K (x = 0.1), 272 K (x = 0.2) and 300 K (x = 0.3). Under a magnetic field of 7 T, the maximum magnetic entropy change was found to be 4.47 J·kg−1·K−1 (x = 0), 4.25 J·kg−1·K−1 (x = 0.1), 3.60 J·kg−1·K−1 (x = 0.2) and 3.28 J·kg−1·K−1 (x = 0.3), respectively. Notably, compared to solid-state reaction method samples, the refrigerating temperature range broadened by 131.25 %, 57.44 %, and 47.45 % for x = 0, 0.1, and 0.2, respectively, using high-pressure heat treatment. Additionally, the x = 0.1 sample exhibited a first-to-second-order phase transition. Analysis of Arrott plots confirmed the first-order phase transition in the parent sample and the second-order phase transition in the doped samples. Furthermore, the Modified Arrott plot, Kouver-Fisher, and local exponent methods revealed that, as the Ba content increased, the critical exponents β, γ, and δ of the samples with second-order phase transition characteristics (doped samples) approached 0.5, 1.0, and 0.667, respectively. The introduction of Ba was found to facilitate the establishment of a second-order phase transition pattern that is more consistent with the mean-field theory model.
期刊介绍:
The Journal of Alloys and Compounds is intended to serve as an international medium for the publication of work on solid materials comprising compounds as well as alloys. Its great strength lies in the diversity of discipline which it encompasses, drawing together results from materials science, solid-state chemistry and physics.