Polymorphism is a very important phenomenon in borates and is helpful when studying their structure and properties.Low-temperature phaseα-LiMB_(9)O_(15)(M=Sr,Pb),crystallized in the chiral space groups P2_(1)2_(1)2_(...Polymorphism is a very important phenomenon in borates and is helpful when studying their structure and properties.Low-temperature phaseα-LiMB_(9)O_(15)(M=Sr,Pb),crystallized in the chiral space groups P2_(1)2_(1)2_(1) and P63,was synthesized via a high-temperature solid reaction,while high-temperature phaseβ-LiMB_(9)O_(15)(M=Sr,Pb)crystallizes in a non-centrosymmetric space group R3c.All of these four phases have three-dimensional structures made up of fundamental building units[B_(3)O_(7)]with six-membered rings,yet the[B_(3)O_(7)]units construct B–O frameworks with different types of three-dimensional channels.The TG-DSC measurements and X-ray diffraction of powders at different temperatures show that α-LiSrB_(9)O_(15) transforms intoβ-LiSrB_(9)O_(15) at 840℃,and the high-temperature β-phase compound is a congruent melting compound.展开更多
基金financially supported by the West Light Foundation of CAS(2020-XBQNXZ-002)the National Natural Science Foundation of China(U2003131,51972336,61835014)+2 种基金the High-Level Professional and Technical Personnel of Autonomous Region,Xinjiang Major Science and Technology Project(2021A01001)the International Partnership Program of CAS(1A1365KYSB20200008)the Instrument Developing Project of CAS(GJJSTD20200007).
文摘Polymorphism is a very important phenomenon in borates and is helpful when studying their structure and properties.Low-temperature phaseα-LiMB_(9)O_(15)(M=Sr,Pb),crystallized in the chiral space groups P2_(1)2_(1)2_(1) and P63,was synthesized via a high-temperature solid reaction,while high-temperature phaseβ-LiMB_(9)O_(15)(M=Sr,Pb)crystallizes in a non-centrosymmetric space group R3c.All of these four phases have three-dimensional structures made up of fundamental building units[B_(3)O_(7)]with six-membered rings,yet the[B_(3)O_(7)]units construct B–O frameworks with different types of three-dimensional channels.The TG-DSC measurements and X-ray diffraction of powders at different temperatures show that α-LiSrB_(9)O_(15) transforms intoβ-LiSrB_(9)O_(15) at 840℃,and the high-temperature β-phase compound is a congruent melting compound.
