基于A位元素置换策略合成新型MAX相材料Ti_3ZnC_2
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摘要
MAX相材料是一类兼具金属和陶瓷特性的三元层状材料,在高温导电、耐磨、耐腐蚀和耐辐照损伤等方面性能优异。目前已经合成出的MAX相材料已有70余种,但A位元素一直局限在ⅢA和ⅣA主族元素,如Al、Si、Ga等,而以副族元素占据A位的MAX相鲜有报道。本研究以Ti_3AlC_2为前驱体,利用熔盐中的A位置换反应,制备出了A位为Zn元素的全新MAX相材料Ti_3ZnC_2。结合X射线衍射、扫描电子显微镜和透射电子显微镜等分析手段对Ti_3ZnC_2的成分和结构进行了确认,并通过密度泛函理论对Ti_3ZnC_2的结构稳定性和晶格参数进行了确定。进一步通过热力学计算对Fe、Co、Ni、Cu等几种元素的A位置换反应进行了预测,发现采用这几种元素的氧化物进行置换反应在热力学上也都具有可行性。本研究所提出的元素置换策略是在保持MAX相六方层状晶体结构的基础上,利用Al、Zn在高温下形成共晶产物实现Zn原子向A层内的迁移,而熔盐介质的存在促进了反应动力学。本方法巧妙地避免了MAX相传统合成过程中竞争相的形成,如M-A合金相,因此可以用于探索更多未知的MAX相材料。
Using Ti_3AlC_2 as the precursor, a new MAX phase Ti_3ZnC_2 was synthesized via an A-elemental substitution reaction in a molten salts bath. Composition and crystal structure of Ti_3ZnC_2 were confirmed by XRD, SEM and TEM analysis. Its structure stability and lattice parameter of Ti_3ZnC_2 were further proved by a theoretical calculation based on density function theory(DFT). Moreover, thermodynamics of A-elemental substitution reactions based on Fe, Co, Ni, and Cu were investigated. All results indicated that the similar substitution reactions are feasible to form series of MAX phases whose A sites are Fe, Co, Ni, and Cu elements. The substitution reaction was achieved by diffusion of Zn atoms into A-layers of Ti_3AlC_2, which requires Al-Zn eutectic formation at high temperatures. The molten salts provided a moderate environment for substitution reaction and accelerated reaction dynamics. The major advantage of this substitution reaction is that MAX phase keeps individual metal carbide layers intact, thus the formation of competitive phases, such as MA alloys, was avoided. The proposed A-elemental sub-stitution reactions approach opens a new door to design and synthesize novel MAX phases which could not be synthesized by the traditional methods.
Using Ti_3AlC_2 as the precursor, a new MAX phase Ti_3ZnC_2 was synthesized via an A-elemental substitution reaction in a molten salts bath. Composition and crystal structure of Ti_3ZnC_2 were confirmed by XRD, SEM and TEM analysis. Its structure stability and lattice parameter of Ti_3ZnC_2 were further proved by a theoretical calculation based on density function theory(DFT). Moreover, thermodynamics of A-elemental substitution reactions based on Fe, Co, Ni, and Cu were investigated. All results indicated that the similar substitution reactions are feasible to form series of MAX phases whose A sites are Fe, Co, Ni, and Cu elements. The substitution reaction was achieved by diffusion of Zn atoms into A-layers of Ti_3AlC_2, which requires Al-Zn eutectic formation at high temperatures. The molten salts provided a moderate environment for substitution reaction and accelerated reaction dynamics. The major advantage of this substitution reaction is that MAX phase keeps individual metal carbide layers intact, thus the formation of competitive phases, such as MA alloys, was avoided. The proposed A-elemental sub-stitution reactions approach opens a new door to design and synthesize novel MAX phases which could not be synthesized by the traditional methods.
引文
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[11]FASHANDI H,LAI C C,DAHLQVIST M,et al.Ti2Au2C and Ti3Au2C2 formed by solid state reaction of gold with Ti2AlC and Ti3AlC2.Chemical Communications,2017,53(69):9554-9557.
[12]LU C,WANG G,YANG G,et al.Substitution behavior of Ag atoms in the Ti2Al C ceramic.Journal of the American Ceramic Society,2017,100(2):732-738.
[13]CLARK S J,SEGALL M D,PICKARD C J,et al.First principles methods using CASTEP.Zeitschrift für KristallographieCrystalline Materials,2005,220(5/6):567-570.
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[15]FRANK W,ELS?SSER C,F?HNLE M.Ab initio force-constant method for phonon dispersions in alkali metals.Physical Review Letters,1995,74:1791-1794.
[16]PARLINSKI K,LI Z Q,KAWAZOE Y.First-principles determination of the soft mode in cubic ZrO2.Physical Review Letters,1997,78:4063-4066.
[17]BORN M.On the stability of crystal lattices.I.Mathematical Proceedings of the Cambridge Philosophical Society,1940,36(2):160-172.
[2]BARSOUM M W,EL-RAGHY T.Synthesis and characterization of a remarkable ceramic:Ti3SiC2.Journal of the American Ceramic Society,1996,79(7):1953-1956.
[3]SUN Z M.Progress in research and development on MAX phases:a family of layered ternary compounds.International Materials Reviews,2011,56(3):143-166.
[4]CHING W Y,MO Y,ARYAL S,et al.Intrinsic mechanical properties of 20 MAX-phase compounds.Journal of the American Ceramic Society,2013,96(7):2292-2297.
[5]SCABAROZI T H,AMINI S,FINKEL P,et al.Electrical,thermal,and elastic properties of the MAX-phase Ti2SC.Journal of Applied Physics,2008,104(3):033502-1-5.
[6]SCABAROZI T,GANGULY A,HETTINGER J D,et al.Electronic and thermal properties of Ti3Al(C0.5,N0.5)2,Ti2Al(C0.5,N0.5),and Ti2Al N.Journal of Applied Physics,104(7):073713-1-6.
[7]HETTINGER J D,LOFLAND S E,FINKEL P,et al.Electrical transport,thermal transport,and elastic properties of M2Al C,(M=Ti,Cr,Nb,and V).Physical Review B,2005,72(11):115120-1-6.
[8]LIU G,CHEN K,ZHOU H,et al.Layered growth of Ti2AlC and Ti3AlC2 in combustion synthesis.Materials Letters,2007,61(3):779-784.
[9]BARSOUM M W,EL-RAGHY T,ALI M.Processing and characterization of Ti2AlC,Ti2AlN,and Ti2AlC0.5N0.5.Metallurgical and Materials Transactions A,2000,31(7):1857-1865.
[10]FASHANDI H,DAHLQVIST M,LU J,et al.Synthesis of Ti3AuC2,Ti3Au2C2 and Ti3Ir C2 by noble metal substitution reaction in Ti3SiC2 for high-temperature-stable Ohmic contacts to SiC.Nature materials,2017,16(8):814-818.
[11]FASHANDI H,LAI C C,DAHLQVIST M,et al.Ti2Au2C and Ti3Au2C2 formed by solid state reaction of gold with Ti2AlC and Ti3AlC2.Chemical Communications,2017,53(69):9554-9557.
[12]LU C,WANG G,YANG G,et al.Substitution behavior of Ag atoms in the Ti2Al C ceramic.Journal of the American Ceramic Society,2017,100(2):732-738.
[13]CLARK S J,SEGALL M D,PICKARD C J,et al.First principles methods using CASTEP.Zeitschrift für KristallographieCrystalline Materials,2005,220(5/6):567-570.
[14]SEGALL M D,LINDAN P J D,PROBERT M J,et al.First-principles simulation:ideas,illustrations and the CASTEPcode.Journal of Physics:Condensed Matter,2002,14(11):2717.
[15]FRANK W,ELS?SSER C,F?HNLE M.Ab initio force-constant method for phonon dispersions in alkali metals.Physical Review Letters,1995,74:1791-1794.
[16]PARLINSKI K,LI Z Q,KAWAZOE Y.First-principles determination of the soft mode in cubic ZrO2.Physical Review Letters,1997,78:4063-4066.
[17]BORN M.On the stability of crystal lattices.I.Mathematical Proceedings of the Cambridge Philosophical Society,1940,36(2):160-172.