Negative area compressibility in silver oxalate
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Negative area compressibility in silver oxalate Francisco Colmenero1,* Zheshuai Lin2,*
, Xingxing Jiang2,*
, Xiaodong Li3, Yanchun Li3, and
1
Department of Molecular Physics, Instituto de Estructura de la Materia (IEM-CSIC), 28006 Madrid, Spain Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China 3 Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China 2
Received: 11 June 2020
ABSTRACT
Accepted: 5 September 2020
The presence of extremely large negative linear compressibilities (NLC) in crystalline silver oxalate was discovered in a recent work by using first principles solid-state calculations. Although the minimum value of the NLC was found for a negative applied hydrostatic pressure, in this work the presence of NLC in this material for positive applied pressures is verified experimentally by means of high-pressure X-ray diffraction experiments performed at room temperature in the Beijing synchrotron radiation facility. The results of this study demonstrate with certainty that the compressibility of silver oxalate along [010] crystallographic direction is negative for applied pressures in the range from 0.0 to 0.85 GPa. Since the measured compressibility decreases largely as the pressure decreases, large negative values of the compressibility are expected for negative applied pressures in agreement with the results found using first principles methods. Furthermore, the analysis of the variation of the lattice parameters of the crystal structure of silver oxalate under pressure in the principal axes reference system revealed that this material also exhibits the largest negative area compressibility phenomenon found so far at zero pressure, the values of the compressibilities along two of the principal axes being - 16.7 and - 20.0 TPa1 . The negative compressibility phenomenon in silver oxalate can be rationalized in terms of a ‘‘chains of rotating parallelograms’’ structural model.
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Springer Science+Business
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Introduction In a recent paper [1], the presence of large negative linear compressibilities (NLC) [2–12] in crystalline silver oxalate, Ag2 C2 O4 ; was discovered by using
high-quality first principles solid-state calculations based in density functional theory employing large plane wave basis sets and pseudopotential functions [13, 14]. In fact, the absolute value of minimum compressibility found for silver oxalate, 1 - 831.9 10 TPa , is the largest found so far and
Handling Editor: Nathan Mara.
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https://doi.org/10.1007/s10853-020-05305-y
J Mater Sci
the range of applied hydrostatic pressures for which this compound exhibits NLC is also the widest found up to date [1]. The crystal structure of silver oxalate, its mechanical properties and the deformation of the crystal structure under pressure at the basis of the NLC p
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