Synthesis,structure,and thermal expansion in CaZrF_(6) with two polymorphs  

作　　者：Peixian Zhang Yongqiang Qiao Kaiyue Zhao Qingjie Wang Huan Zhao Juan Guo Erjun Liang Tao Sun Jiangwei Zhang Qilong Gao 

机构地区：[1]Key Laboratory of Materials Physics of Ministry of Education,School of Physics and Microelectronics,Zhengzhou University,Zhengzhou 450052,China [2]College of Energy Materials and Chemistry,Inner Mongolia University,Hohhot 010021,China [3]First Affiliated Hospital of Dalian Medical University,222 Zhongshan Road,Dalian 116011,China [4]Ordos Laboratory,Ordos 017000,China

出　　处：《Nano Research》2024年第9期8618-8626,共9页纳米研究（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.22071221,12374032,and U22A20107);the Natural Science Foundation of Henan Province(No.222301420040);China Postdoctoral Science Foundation(No.2023M743152);the State Key Laboratory of Refractories and Metallurgy(Wuhan University of Science and Technology)(No.G202306);“Grassland Talents”of Inner Mongolia Autonomous Region,Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region(No.NJYT23030);“Steed plan High level Talents”of Inner Mongolia University,Carbon neutralization research project(No.STZX202218);Inner Mongolia Autonomous Region Natural Science Foundation(No.2023MS02002);the National Key R&D Program of China(No.2022YFA1205201).

摘　　要：Due to the high structural flexibility and controllable thermal expansion,cubic double ReO_(3)-type negative thermal expansion(NTE)fluorides provide a solution for solving the prominent phenomenon of thermal expansion mismatch between materials.However,the expensive raw materials and complex synthesis steps limit its practical application.In this work,we have designed a more advantageous method for the synthesis of NTE material CaZrF_(6),and it is expected to be generalized to the synthesis of other double ReO_(3)-fluorides.Intriguingly,a new orthorhombic phase CaZrF_(6) has been synthesized via this method in a lower temperature.Unlike the strong isotropic NTE of the cubic phase CaZrF_(6),the orthorhombic phase shows the strong anisotropic positive thermal expansion(PTE).The combined analysis of temperature-dependent X-ray diffraction(XRD),Raman spectra,and first-principles calculations shows that the low frequency phonon vibration mode with negative Grüneisen parameter in cubic CaZrF_(6) are strongly correlated with the transverse thermal vibration of F atoms and dominates the NTE of the material.

关 键 词：negative thermal expansion fluorides POLYMORPH lattice dynamics first principles calculations 

分 类 号：O62[理学—有机化学]