Grain size and structure distortion characterization of <i>α</i>-MgAgSb thermoelectric material by powder diffraction

Xiyang Li; Zhigang Zhang; Lunhua He; Maxim Avdeev; Yang Ren; Huaizhou Zhao; Fangwei Wang

doi:10.1088/1674-1056/aba09c

Chinese Physics B, Volume. 29, Issue 10, (2020)

Grain size and structure distortion characterization of α-MgAgSb thermoelectric material by powder diffraction

Xiyang Li1...2, Zhigang Zhang1,3, Lunhua He1,3, Maxim Avdeev4, Yang Ren5, Huaizhou Zhao1, and Fangwei Wang1,23,† |Show fewer author(s)

Author Affiliations

¹Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 0090, China

²School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 101408, China

³Songshan Lake Materials Laboratory, Dongguan 52808, China

⁴Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 223, Australia

⁵X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA

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Figures & Tables(5)

$(a) Crystalline structure of α-MgAgSb, the space group is I-4c2 (No. 120). (b) The neutron diffraction, and synchrotron x-ray diffraction data of MgAg0.97Sb0.99 measured at room temperature.$

Fig. 1. (a) Crystalline structure of α-MgAgSb, the space group is I-4c2 (No. 120). (b) The neutron diffraction, and synchrotron x-ray diffraction data of MgAg_0.97Sb_0.99 measured at room temperature.

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$Rietveld refinement of MgAg0.97Sb0.99 neutron diffraction data with size parameter refined (a), and without size parameter refined (b).$

Fig. 2. Rietveld refinement of MgAg_0.97Sb_0.99 neutron diffraction data with size parameter refined (a), and without size parameter refined (b).

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$Rietveld refinement of MgAg0.97Sb0.99 synchrotron x-ray diffraction data with size parameter refined (a), and without size parameter refined (b).$

Fig. 3. Rietveld refinement of MgAg_0.97Sb_0.99 synchrotron x-ray diffraction data with size parameter refined (a), and without size parameter refined (b).

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Fig. 4. Static structure distortion in MgAg_0.97Sb_0.99. The refined bond distances and bond angles of the nearest Mg–Sb bonds are shown in Table 1. The refinement results show a significant distortion of this Mg–Sb formed distorted NaCl structure.

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Table 1. Refined parameters of MgAg_0.97Sb_0.99 measured by high resolution neutron diffraction and synchrotron x-ray diffraction, respectively.

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Table 1. Refined parameters of MgAg_0.97Sb_0.99 measured by high resolution neutron diffraction and synchrotron x-ray diffraction, respectively.

		Neutron diffraction	X-ray diffraction
Cell parameters:
a, b/Å		9.1706(7)	9.1723(3)
c/Å		12.7082(9)	12.7100(4)
V/Å³		1068.8(2)	1069.1(2)
Atom parameters:
Mg	x	−0.0232(4)	−0.030(2)
	y	0.2837(4)	0.284(2)
	z	0.1101(3)	0.1128(9)
Ag1	x	{0}	{0}
	y	0	0
	z	0.25	0.25
Ag2	x	0	0
	y	0	0
	z	0	0
Ag3	x	0.2239(3)	0.2243(4)
	y	0.2239(3)	0.2243(4)
	z	0.25	0.25
Sb	x	0.2353(4)	0.2357(3)
	y	0.4751(4)	0.4767(3)
	z	0.1180(3)	0.1172(2)
Mg–Sb bond distances:
b1/Å		2.937(5)	2.97(2)
b2/Å		2.948(4)	2.90(2)
b3/Å		2.952(4)	3.02(2)
b4/Å		3.247(4)	3.21(2)
b5/Å		3.460(5)	3.44(2)
b6/Å		3.871(4)	3.90(2)
Mg-Sb bond angles:
b1–b2/(°)		100.2(3)	99.9(3)
b1–b3/(°)		87.0(2)	85.4(3)
b1–b4/(°)		95.2(2)	94.8(3)
b1–b6/(°)		83.1(2)	81.7(3)
b2–b3/(°)		94.7(2)	94.6(3)
b2–b4/(°)		95.6(2)	97.5(3)
b2–b5/(°)		90.0(2)	91.8(3)
b3–b5/(°)		90.0(2)	89.8(3)
b3–b6/(°)		83.5(2)	82.1(3)
b4–b5/(°)		86.0(2)	87.5(3)
b4–b6/(°)		86.0(2)	85.8(3)
b5–b6/(°)		86.6(2)	86.3(2)
X and Y parameters:
X/(°)		–	0.36431
Y/(°)		0.184(6)	0.0012(2)
Size parameters:
GausSiz/(°)²		0.008(2)	0.000617(3)
Grain size/nm		28(4)	24(1)
Reliability factors^a:
R_wp/%		10.8	9.94
χ²		1.98	10.2

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Xiyang Li, Zhigang Zhang, Lunhua He, Maxim Avdeev, Yang Ren, Huaizhou Zhao, Fangwei Wang. Grain size and structure distortion characterization of α-MgAgSb thermoelectric material by powder diffraction[J]. Chinese Physics B, 2020, 29(10):

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Paper Information

Received: May. 21, 2020

Accepted: --

Published Online: Apr. 21, 2021

The Author Email: Wang Fangwei (fwwang@iphy.ac.cn)

DOI:10.1088/1674-1056/aba09c

Topics

Nuclear physics

Particles and fields

Particle and nuclear astrophysics and cosmology

Table 1. Refined parameters of MgAg0.97Sb0.99 measured by high resolution neutron diffraction and synchrotron x-ray diffraction, respectively.

Table 1. Refined parameters of MgAg0.97Sb0.99 measured by high resolution neutron diffraction and synchrotron x-ray diffraction, respectively.

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Table 1. Refined parameters of MgAg_0.97Sb_0.99 measured by high resolution neutron diffraction and synchrotron x-ray diffraction, respectively.

Table 1. Refined parameters of MgAg_0.97Sb_0.99 measured by high resolution neutron diffraction and synchrotron x-ray diffraction, respectively.