The Structure and Magnetic Properties of SmCo5-type Medium- and High-entropy Intermetallic Compounds
-
摘要: 以SmCo5为原型,设计了3种中熵金属间化合物(Sm1/3Ce1/3Pr1/3)Co5、(Sm1/3Ce1/3Nd1/3)Co5、(Sm1/3Pr1/3Nd1/3)Co5和1种高熵金属间化合物(Sm1/4Ce1/4Pr1/4Nd1/4)Co5,并采用原子半径差和混合焓预测了形成单相结构的可能性. 应用真空电弧熔炼技术成功制备了4种金属间化合物. 采用X射线衍射仪(XRD)、能谱仪(EDS) 和振动样品磁强计(VSM) 表征了样品的物相、成分和磁学性能. 结果表明:4种化合物均为单相,具有六方CaCu5结构,空间群为P6/mmm,稀土原子占据1a位置;稀土位置上的原子浓度为等原子比;化合物的室温磁化行为遵循Langevin模型,磁化强度依赖于化合物的成分;磁价模型计算证实了化合物(Sm1/3Ce1/3Pr1/3)Co5、(Sm1/3Ce1/3Nd1/3)Co5和(Sm1/4Ce1/4Pr1/4Nd1/4)Co5中的Ce为+4价,对磁矩没有贡献.Abstract: Three medium-entropy intermetallic compounds (Sm1/3Ce1/3Pr1/3)Co5, (Sm1/3Ce1/3Nd1/3)Co5 and (Sm1/3Pr1/3Nd1/3)Co5 and a high-entropy intermetallic compound (Sm1/4Ce1/4Pr1/4Nd1/4)Co5 were designed on the basis of SmCo5. The possibility of forming single-phase structure was predicted using atomic size difference and mixing enthalpy. Four intermetallics were synthesized via the vacuum arc-melting technology. The X-ray diffractometer (XRD), the energy dispersive X-ray spectrometer (EDS) and the vibration sample magnetometer (VSM) were used to study the phase, chemical compositions and magnetic properties. The results show that four intermetallics are single-phase structures and crystalline in a hexagonal CaCu5 structure with a space group of P6/mmm. The rare earth atoms occupy 1a site. The atomic concentration at the rare earth site is equiatomic ratio. The room temperature magnetizations follow the Langevin model. Magnetization depends on the composition of the compound. The magnetic valence model was employed to check the valence of Ce. The calculated results show that Ce is tetravalent in (Sm1/3Ce1/3Pr1/3)Co5, (Sm1/3Ce1/3Nd1/3)Co5 and (Sm1/4Ce1/4Pr1/4Nd1/4)Co5 and makes no contribution to the magnetic moment.
-
Key words:
- high-entropy /
- SmCo5 /
- intermetallic compound /
- single phase /
- magnetic properties
-
表 1 (Sm1/4Ce1/4Pr1/4Nd1/4)Co5衍射峰的指标化结果
Table 1. The index results of diffraction peaks in compound (Sm1/4Ce1/4Pr1/4Nd1/4)Co5
晶面 2θ实验值 2θ计算值 100 20.518 20.518 001 22.241 22.251 101 30.459 30.447 110 35.959 35.934 200 41.740 41.733 111 42.680 42.674 002 45.420 45.402 201 47.820 47.795 112 59.238 59.215 211 61.220 61.218 202 63.343 63.360 300 64.563 64.591 301 69.221 69.231 103 74.543 74.553 220 76.200 76.186 注:M(15)=109,F(15)=58. 表 2 (Sm, R)Co5(R=Ce, Pr, Nd) 化合物的晶格参数、品质因子与可信度因子
Table 2. The lattice parameters, quality factors and credibility factors of (Sm, R)Co5 (R=Ce, Pr, Nd) compounds
晶格参数 a/nm c/nm V/nm3 M F (Sm1/3Ce1/3Pr1/3)Co5 0.498 6(7) 0.399 2(7) 0.085 98 181 81 (Sm1/3Ce1/3Nd1/3)Co5 0.498 7(3) 0.299 0(5) 0.085 96 177 98 (Sm1/3Pr1/3Nd1/3)Co5 0.500 4(4) 0.397 6(5) 0.086 25 105 55 (Sm1/4Ce1/4Pr1/4Nd1/4)Co5 0.499 4(2) 0.399 1(9) 0.086 23 109 58 表 3 (Sm, R)Co5 (R=Ce, Pr, Nd)化合物的Rietveld精修结果
Table 3. The Rietveld refined results of (Sm, R)Co5 (R=Ce, Pr, Nd) compounds
晶格参数 (Sm1/3Ce1/3Pr1/3)Co5 (Sm1/3Ce1/3Nd1/3)Co5 (Sm1/3Pr1/3Nd1/3)Co5 (Sm1/4Ce1/4Pr1/4Nd1/4)Co5 a/nm 0.498 51 0.498 45 0.500 82 0.499 25 c/nm 0.399 31 0.399 02 0.397 84 0.399 08 V/nm3 0.085 94 0.085 85 0.086 42 0.086 14 1a(0, 0, 0) Sm Sm Sm Sm Ce Ce — Ce Pr — Pr Pr — Nd Nd Nd 2c(1/3, 2/3, 0) Co Co Co Co 3g(1/2, 0, 1/2) Co Co Co Co Rp/% 6.190 7.515 7.556 6.705 Rwp/% 8.044 9.660 10.028 8.585 s 1.558 1.561 1.363 1.376 注:空间群为P6/mmm. 表 4 (Sm, R)Co5 (R=Ce, Pr, Nd)化合物的成分分析结果
Table 4. The results of composition analysis of (Sm, R) CO5 (R=Ce, Pr, Nd) compounds
元素 (Sm1/3Ce1/3Pr1/3)Co5 (Sm1/3Ce1/3Nd1/3)Co5 (Sm1/3Pr1/3Nd1/3)Co5 (Sm1/4Ce1/4Pr1/4Nd1/4)Co5 Sm 5.57 5.62 5.76 3.94 Ce 5.39 5.43 — 4.17 Pr 5.72 — 5.49 3.97 Nd — 5.73 5.38 4.01 Co 83.32 83.22 83.36 83.91 表 5 (Sm, R)Co5 (R=Ce, Pr, Nd)化合物的计算磁矩
Table 5. The calculated moments of (Sm, R)Co5 (R=Ce, Pr, Nd) compounds
化合物 μB实验值 Ce3+的计算结果 Ce4+的计算结果 μB计算值 Nsp↑ 误差/% μB计算值 Nsp↑ 误差/% (Sm1/3Ce1/3Pr1/3)Co5 6.24 7.02 0 12.50 6.30 0 0.96 (Sm1/3Ce1/3Nd1/3)Co5 6.37 7.04 0 10.52 6.33 0 0.63 (Sm1/3Pr1/3Nd1/3)Co5 8.74 8.60 0.1 1.60 8.60 0.1 1.60 (Sm1/4Ce1/4Pr1/4Nd1/4)Co5 6.88 7.33 0 6.54 6.80 0 1.16 -
[1] YEH J W, LIN S J, CHIN T S, et al. Formation of simple crystal structures in Cu-Co-Ni-Cr-Al-Fe-Ti-V alloys with multiprincipal metallic elements[J]. Metallurgical & Materials Transactions A, 2004, 35(8): 2533-2536. doi: 10.1007/s11661-006-0234-4 [2] JUAN C C, TSAI M H, TSAI C W, et al. Enhanced mechanical properties of HfMoTaTiZr and HfMoNbTaTiZr refractory high-entropy alloys[J]. Intermetallics, 2015, 62: 76-83. doi: 10.1016/j.intermet.2015.03.013 [3] NENE S S, FRANK M, LIU K, et al. Corrosion-resistant high entropy alloy with high strength and ductility[J]. Scripta Materialia, 2019, 166: 168-172. doi: 10.1016/j.scriptamat.2019.03.028 [4] LI J, GAO B, TANG S, et al. High temperature deformation behavior of carbon-containing FeCoCrNiMn high entropy alloy[J]. Journal of Alloys and Compounds, 2018, 747: 571-579. doi: 10.1016/j.jallcom.2018.02.332 [5] LI P, WANG A, LIU C T. A ductile high entropy alloy with attractive magnetic properties[J]. Journal of Alloys and Compounds, 2017, 694: 55-60. doi: 10.1016/j.jallcom.2016.09.186 [6] MISHRA R K, SHAHI R R. Effect of annealing conditions and temperatures on phase formation and magnetic beha-viour of CrFeMnNiTi high entropy alloy[J]. Journal of Magnetism and Magnetic Materials, 2018, 465: 169-175. doi: 10.1016/j.jmmm.2018.04.056 [7] YANG T, ZHAO Y L, TONG Y, et al. Multicomponent intermetallic nanoparticles and superb mechanical behaviors of complex alloys[J]. Science, 2018, 362: 933-937. doi: 10.1126/science.aas8815 [8] YADAV T P, MUKHOPADHYAY S, MISHRA S S, et al. Synthesis of a single phase of high-entropy Laves intermetallics in the Ti-Zr-V-Cr-Ni equiatomic alloy[J]. Philosophical Magazine Letters, 2017, 97(12): 494-503. doi: 10.1080/09500839.2017.1418539 [9] ZHOU N, JIANG S, HUANG T, et al. Single-phase high-entropy intermetallic compounds (HEICs): bridging high-entropy alloys and ceramics[J]. Science Bulletin, 2019, 64(12): 856-864. doi: 10.1016/j.scib.2019.05.007 [10] STRNAT K J, STRNAT R M W. Rare earth-cobalt permanent magnets[J]. Journal of Magnetism and Magnetic Materials, 1991, 100(1): 38-56. [11] NORDSTR M L, ERIKSSON O, BROOKS M S S, et al. Theory of ferromagnetism in CeCo5[J]. Physical Review B, 1990, 41(13): 9111-9120. doi: 10.1103/PhysRevB.41.9111 [12] FRANSE J J M, RADWAŃSKI R J. Handbook of magne-tic materials[M]. Amsterdam: Elsevier, 1993: 307-501. [13] PARETI L, MOZE O, SOLZI M, et al. Magnetocrystalline anisotropy in Y1-xPrxCo5[J]. Journal of Applied Phy-sics, 1988, 63(1): 172-175. doi: 10.1063/1.340485 [14] RAO J E G U S. An analysis of the rare earth contribution to the magnetic anisotropy in RCo5 and R2Co17 compounds[J]. Journal of Solid State Chemistry, 1973, 6: 387-395. doi: 10.1016/0022-4596(73)90228-4 [15] ALAMEDA J M, GIVORD D, LEMAIRE R Q, et al. Co energy and magnetization anisotropies in RCo5 intermetallics between 4.2 K and 300 K[J]. Journal of Applied Physics, 1981, 52(3): 2079-2081. doi: 10.1063/1.329622 [16] WANG K, ZHANG M, OUYANG Y, et al. Enhancement of rotating magnetocaloric effect by Fe substitution in NdCo5-xFex alloys[J]. Intermetallics, 2020, 118: 106676/1-7. http://www.sciencedirect.com/science/article/pii/S0966979519309458 [17] 梁翠芬, 熊予莹, 初本莉, 等. 磁性纳米Fe3O4/TiO2复合材料的制备[J]. 华南师范大学学报(自然科学版), 2010(2): 63-66. https://www.cnki.com.cn/Article/CJFDTOTAL-HNSF201002014.htmLIANG C F, XIONG Y Y, CHU B L, et al. Sythesis of magnetie nanometer Fe3O4 powder and Fe3O4/TiO2 composite material[J]. Journal of South China Normal University(Natural Science Edition), 2010(2): 63-66. https://www.cnki.com.cn/Article/CJFDTOTAL-HNSF201002014.htm [18] 戚平, 周庆琼, 林子豪, 等. 磁性固相萃取-液相色谱法测定环境水样中多种碱性染料[J]. 华南师范大学学报(自然科学版), 2015, 47(2): 58-66. https://www.cnki.com.cn/Article/CJFDTOTAL-HNSF201502011.htmQI P, ZHOU Q Q, LIN Z H, et al. Determination of basic dyes in environmental water by magnetic solid phase extraction high performance liquid chromatography[J]. Journal of South China Normal University(Natural Science Edition), 2015, 47(2): 58-66. https://www.cnki.com.cn/Article/CJFDTOTAL-HNSF201502011.htm [19] FANG L, ZHANG T, WANG H, et al. Effect of ball milling process on coercivity of nanocrystalline SmCo5 magnets[J]. Journal of Magnetism and Magnetic Materials, 2018, 446: 200-205. doi: 10.1016/j.jmmm.2017.09.012 [20] CUI B Z, LI W F, HADJIPANAYIS G C. Formation of SmCo5 single-crystal submicron flakes and textured polycrystalline nanoflakes[J]. Acta Materialia, 2011, 59(2): 563-571. doi: 10.1016/j.actamat.2010.09.060 [21] TAKEUCHI A, AKIHISA I. Classification of bulk metallic glasses by atomic size difference, heat of mixing and period of constituent elements and its application to characterization of the main alloying element[J]. Materials Transactions, 2005, 46(12): 2817-2829. doi: 10.2320/matertrans.46.2817 [22] YANG X, ZHANG Y. Prediction of high-entropy stabilized solid-solution in multi-component alloys[J]. Materials Chemistry and Physics, 2012, 132(2/3): 233-238. http://www.sciencedirect.com/science/article/pii/S0254058411009357 [23] GUO X P, GUO Y Q. Effects on structure and magnetic properties of SmCo5 based intermetallic compounds by increasing configuration entropy from binary to quaternary equiatomic rare earths at Sm site[J]. Journal of Alloys and Compounds, 2020, 813: 152230/1-8. -