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Above-Room-Temperature LiNbO3-Type Polar Magnet Stabilized by Chemical and Physical Pressure TEXT SIZE: A A A
LiNbO3 (LN)-type polar magnets are technologically important but require stringent and costly high-pressure synthesis with very limited sample yields. We develop a chemical strategy to reduce the physical synthesis pressure. LN-type polar magnets require 7 GPa to stabilize in the high-pressure Mn2FeNbO6 (MFNO) phase. Here, MFNO was successfully stabilized in the isostructural LN matrix at intermediate physical pressure (below 5 GPa) at gram levels for each run by dilution with LN according to (Li1-xMnx)(Fex/2Nb1-x/2)O-3 (x = 0.18, 0.33, 0.46, 0.57). LN-diluted MFNO demonstrates ferromagnetism above room-temperature (magnetic ordering temperature T-C approximate to 516-554 K) and has large estimated spontaneous polarization (P-S approximate to 18-63 mu C/cm(2)). Irreversible c-axis near-zero thermal expansion stemming from magnetostriction was observed around the magnetic transition temperature region upon heating at ambient pressure, which irreversibly elongates the distance between the face-sharing (Li/Mn) and (Fe/Nb) octahedral centroids along the c-axis and thus weakens the magnetic interactions. The magnetic ordering temperature drops in the annealed samples. The findings in (Li1-xMnx)(Fex/2Nb1-x/2)O-3 show that polar magnets can be made by chemical pressure together with soft physical pressure and shed light on large-scale and lower cost stabilization of high-pressure phases.
 

Publication name

 CHEMISTRY OF MATERIALS Volume: 32 Issue: 4 Pages: 1618-1626 DOI: 10.1021/acs.chemmater.9b05051 Published: FEB 25 2020

Author(s)

 Han, Yifeng; Zhu, Chuanhui; Peng, Yi; Li, Shufang; Wu, MeiXia; Zhao, Shuang; Deng, Zheng; Jin, Changqing; Du, Wei; Walker, David; Li, Man-Rong

Corresponding author(s) 

 LI Manrong 
 limanrong@mail.sysu.edu.cn  
 Sun Yat Sen Univ, Sch Chem, Minist Educ, Key Lab Bioinorgan & Synthet Chem, Guangzhou 510275, Peoples R China.

Author(s) from IGCAS   DU Wei

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