Influence of Preparation Processes on the Structure and Properties of the Ductile Thermoelectric Material Ag2S0.4Te0.6

doi:10.15541/jim20260018

Abstract

Abstract:

Ag₂S_0.4Te_0.6 is an inorganic semiconductor with favorable ductility and thermoelectric performance, showing potential for applications in wearable electronics. Recent studies have indicated that optimization of preparation processes, such as annealing, can significantly enhance the ductility of the material, which is closely related to its phase composition and crystal structure. In this work, high-resolution synchrotron radiation powder X-ray diffraction data of the Ag₂S_0.4Te_0.6 powder sample before and after annealing were collected over a temperature range of 110-700 K. By combining Rietveld structural refinement, high-resolution transmission electron microscopy, and atomic pair distribution function analysis, the influence of the annealing process on the phase composition and structural evolution behavior of the powder samples was investigated in detail. The results show that the pristine Ag₂S_0.4Te_0.6 powder is predominantly amorphous, containing only a small amount of poorly crystalline monoclinic phase. During heating, the material gradually crystallizes, first forming a monoclinic phase, which subsequently transforms into mixed body-centered cubic (bcc) and face-centered cubic (fcc) phases. After cooling back to room temperature, the sample remains in a mixed state of bcc-dominated cubic crystallinity and amorphous phase. In contrast, the annealed powder sample already exhibits a mixed cubic crystalline/amorphous state at room temperature, and no obvious phase transition behavior is observed during heating. Moreover, the thermoelectric properties of Ag₂S_0.4Te_0.6 bulk sample remain largely unaffected by the annealing process. This study provides structural insights for further understanding the annealing-induced improvement in ductility of Ag₂S_0.4Te_0.6 materials.

Key words: Ag₂S_0.4Te_0.6, thermoelectric material, synchrotron radiation, structural evolution, annealing

CLC Number:

TB34

LIU Jinxiao, LIU Zhenhan, CHEN Xingyu, ZHOU Zhengyang, QIU Pengfei, ZHANG Jiawei, SHI Xun. Influence of Preparation Processes on the Structure and Properties of the Ductile Thermoelectric Material Ag₂S_0.4Te_0.6[J]. Journal of Inorganic Materials, 2026, 41(7): 939-946.

Figures/Tables 12

Fig. 1 BSE images of (a) pristine and (b) annealed Ag2S0.4Te0.6 bulk samples, along with EDS elemental distribution mappings of Ag, Te and S

Fig. 2 (a, b) SPXRD patterns (λ=0.490027(0) Å) and (c, d) DSC curves of (a, c) pristine and (b, d) annealed Ag2S0.4Te0.6 powder samples

Fig. 3 Rietveld refinement of SPXRD data of samples using (a) monoclinic Ag2Te, (b-f) bcc Ag2Te, and (g-i) fcc Ag2Te as models

Fig. 4 (a) HRTEM image of amorphous region in the pristine Ag2S0.4Te0.6 powder sample with inset showing the fast Fourier transform (FFT) image corresponding to area marked by the white square; (b) HRTEM image of the annealed Ag2S0.4Te0.6 powder sample showing a crystalline matrix with a bcc structure embedded in an amorphous region with inset showing the FFT image of the crystalline area; (c) SAED pattern and (d) IFFT image corresponding to the crystalline region marked in panel Fig. (b)

Fig. 5 Temperature-dependent curves of (a) electrical conductivity, (b) Seebeck coefficient, (c) power factor, (d) total thermal conductivity, and (e) thermoelectric figure of merit zT for pristine and annealed Ag2S0.4Te0.6 bulk sample

Fig. S1 BSE images of the (a) pristine and (b) annealed Ag2S0.4Te0.6 bulk samples Red circles indicate the selected regions for EDS point analysis

Table S1 Atomic percentages of the element distribution at the designated detection points in the pristine bulk sample

Point	#1	#2	#3	#4	#5	#6	#7	Average
Ag/%	67.5	67.5	67.4	67.0	67.8	67.1	67.4	67.4
Te/%	19.5	19.7	19.7	19.6	19.6	19.3	19.4	19.5
S/%	13.0	12.8	12.9	13.3	12.6	13.6	13.2	13.1

Table S2 Atomic percentages of the element distribution at the designated detection points in the annealed bulk sample

Point	#1	#2	#3	#4	#5	#6	#7	Average
Ag/%	67.5	68.0	67.4	68.2	67.9	67.4	67.4	67.7
Te/%	19.5	19.3	19.7	19.0	19.5	19.8	19.9	19.5
S/%	13.0	12.7	12.9	12.8	12.6	12.8	12.7	12.8

Table S3 Rietveld refinement of SPXRD data for the bcc Ag2Te phase

Temperature		600 K (pristine)	700 K (pristine)	300 K (pristine, after cycling)	300 K (annealed)	300 K (annealed, after cycling)
No. of points		30052	30052	30057	30062	30059
No. of reflections		52	53	51	52	52
No. of parameters		15	16	16	16	16
R_p/%		1.84	1.84	2.08	2.20	2.12
R_wp/%		3.12	4.12	3.78	3.05	3.66
GOF		4.54	5.02	5.48	2.20	2.98
a=b=c/Å		5.1031(8)	5.1263(13)	5.0481(6)	5.0420(2)	5.0536(10)
Volume/Å³		132.8930(4)	134.7170(6)	128.6440(3)	128.1770(9)	129.0650(4)
U_iso/Å²	Ag1	0.2084(6)	0.2077(7)	0.1917(18)	0.1861(18)	0.1892(13)
	Te1	0.1068(7)	0.1102(13)	0.0887(7)	0.0944(15)	0.0955(9)
	S1	0.1068(7)	0.1102(13)	0.0887(7)	0.0944(15)	0.0955(9)
Occupancy	Ag1	0.3333	0.3333	0.3522(15)	0.3333	0.3461(12)
	Te1	0.6	0.6	0.6(6)	0.6	0.6
	S1	0.4	0.4	0.3999(6)	0.4	0.4

Table S4 Rietveld refinement of the SPXRD data for the fcc Ag2Te phase

Temperature		700 K (pristine)	300 K (annealed)	300 K (annealed, after cycling)
No. of points		30052	30062	30059
No. of reflections		58	62	58
No. of parameters		17	17	16
R_p/%		1.34	2.29	3.23
R_wp/%		2.44	4.01	5.43
GOF		2.87	3.13	4.42
a=b=c/Å		6.4927(14)	6.4140(4)	6.3978(6)
Volume/Å³		273.6970(10)	263.9000(3)	261.8700(4)
U_iso/Å²	Ag1	0.0546(4)	0.0547(3)	0.0550(4)
	Ag2	0.1926(4)	0.1800(3)	0.1795(4)
	Te1	0.1795(2)	0.1752(3)	0.1750(7)
	S1	0.1795(2)	0.1752(3)	0.1750(7)
Occupancy	Ag1	0.1345(6)	0.1330(2)	0.1435(3)
	Ag2	0.0703(6)	0.0766(2)	0.0613(3)
	Te1	0.6050(7)	0.6060(3)	0.6094(4)
	S1	0.3950(7)	0.3940(3)	0.3906(4)

Fig. S2 (a, b) PDF spectra at different temperatures for (a) pristine and (b) annealed powder samples in the range of 2-40 Å with inset showing the PDF spectra in the short range of 2-6 Å; (c, d) Synchrotron radiation X-ray PDF spectra of (c) pristine powder at 700 K and (d) annealed powder at 300 K in the range of 2-6 Å fitted with average structures from the Im¯3m and Fm¯3m space groups, together with partial PDF data for different atomic pairs; (e) Synchrotron radiation X-ray PDF spectra for pristine Ag2S0.4Te0.6 at 700 K in the range of 2-30 Å Blue circles are fitted using the average structures of the Im¯3m and Fm¯3m space groups, with the fitting model displayed as a red line and the difference curve as a green line (with offset shown below the data and fit)

Fig. S3 Synchrotron radiation X-ray PDF patterns of Ag2S0.4Te0.6 powder (a) before annealing at 600 K and (b) after annealing at 300 K

References 47

[1]	LIM H R, KIM H S, QAZI R, et al. Advanced soft materials, sensor integrations, and applications of wearable flexible hybrid electronics in healthcare, energy, and environment. Advanced Materials, 2020, 32(15): e1901924.
[2]	GUO C F, DING L M. Integration of soft electronics and biotissues. The Innovation, 2021, 2(1): 100074. DOI URL
[3]	MENG B, TANG W, TOO Z H, et al. A transparent single-friction-surface triboelectric generator and self-powered touch sensor. Energy & Environmental Science, 2013, 6(11): 3235.
[4]	BOLAND C S, KHAN U, RYAN G, et al. Sensitive electromechanical sensors using viscoelastic graphene-polymer nanocomposites. Science, 2016, 354(6317): 1257. PMID
[5]	YANG Q Y, YANG S Q, QIU P F, et al. Flexible thermoelectrics based on ductile semiconductors. Science, 2022, 377(6608): 854. DOI PMID
[6]	HOU C Y, ZHU M F. Semiconductors flex thermoelectric power. Science, 2022, 377(6608): 815. DOI PMID
[7]	PERUMAL S, ROYCHOWDHURY S, BISWAS K. Reduction of thermal conductivity through nanostructuring enhances the thermoelectric figure of merit in Ge_1-_xBi_xTe. Inorganic Chemistry Frontiers, 2016, 3(1): 125. DOI URL
[8]	PERUMAL S, SAMANTA M, GHOSH T, et al. Realization of high thermoelectric figure of merit in GeTe by complementary co-doping of Bi and In. Joule, 2019, 3(10): 2565. DOI URL
[9]	BU Z L, ZHANG X Y, SHAN B, et al. Realizing a 14% single-leg thermoelectric efficiency in GeTe alloys. Science Advances, 2021, 7(19): eabf2738.
[10]	JIANG Y L, DONG J F, ZHUANG H L, et al. Evolution of defect structures leading to high ZT in GeTe-based thermoelectric materials. Nature Communications, 2022, 13: 6087. DOI PMID
[11]	XING T, ZHU C X, SONG Q F, et al. Ultralow lattice thermal conductivity and superhigh thermoelectric figure-of-merit in (Mg, Bi) Co-doped GeTe. Advanced Materials, 2021, 33(17): 2008773. DOI URL
[12]	WANG J, LI J B, YU H Y, et al. Enhanced thermoelectric performance in n-type SrTiO₃/SiGe composite. ACS Applied Materials & Interfaces, 2020, 12(2): 2687.
[13]	BASU R, SINGH A. High temperature Si-Ge alloy towards thermoelectric applications: a comprehensive review. Materials Today Physics, 2021, 21: 100468. DOI URL
[14]	CHEN H B, ZHANG Z W, LIANG J S, et al. Phonon relaxation effect by regeneration of nano-inclusions in SiGe for ultralow thermal conductivity and enhanced thermoelectric performance. Materials Today Physics, 2024, 43: 101405. DOI URL
[15]	JIANG Z X, LI E L, SHI R Z, et al. Effective nonstoichiometric strategy combined post-annealing process for boosting thermoelectric properties in n-type PbTe. ACS Applied Materials & Interfaces, 2024, 16(15): 19048.
[16]	MA B P, LI Y Q, ZHU L J, et al. Modulation doping promoted ultrahigh electron mobility and enhanced thermoelectric performance in PbTe. Chemical Engineering Journal, 2024, 488: 150647. DOI URL
[17]	CAO Y, BAI H, LI Z, et al. Zn-induced defect complexity for the high thermoelectric performance of n-type PbTe compounds. ACS Applied Materials & Interfaces, 2021, 13(36): 43134.
[18]	CAO T Y, SHI X L, CHEN Z G. Advances in the design and assembly of flexible thermoelectric device. Progress in Materials Science, 2023, 131: 101003. DOI URL
[19]	JUNG S J, SHIN J, LIM S S, et al. Porous organic filler for high efficiency of flexible thermoelectric generator. Nano Energy, 2021, 81: 105604. DOI URL
[20]	ZHANG Q, SUN Y M, QIN Y K, et al. Two soluble polymers with lower ionization potentials: doping and thermoelectric properties. Journal of Materials Chemistry A, 2016, 4(4): 1432. DOI URL
[21]	AÏCH R B, BLOUIN N, BOUCHARD A, et al. Electrical and thermoelectric properties of poly(2,7-carbazole) derivatives. Chemistry of Materials, 2009, 21(4): 751. DOI URL
[22]	SHI X, CHEN H Y, HAO F, et al. Room-temperature ductile inorganic semiconductor. Nature Materials, 2018, 17(5): 421. DOI PMID
[23]	ZHAO P, XUE W H, ZHANG Y, et al. Plasticity in single- crystalline Mg₃Bi₂ thermoelectric material. Nature, 2024, 631: 777. DOI
[24]	LI A R, WANG Y C, LI Y Z, et al. High performance magnesium- based plastic semiconductors for flexible thermoelectrics. Nature Communications, 2024, 15: 5108. DOI
[25]	HU H P, WANG Y C, FU C G, et al. Achieving metal-like malleability and ductility in Ag₂Te_1-_xS_x inorganic thermoelectric semiconductors with high mobility. The Innovation, 2022, 3(6): 100341. DOI URL
[26]	YANG S Q, GAO Z Q, QIU P F, et al. Ductile Ag₂₀S₇Te₃ with excellent shape-conformability and high thermoelectric performance. Advanced Materials, 2021, 33(10): 2007681. DOI URL
[27]	WEI T R, JIN M, WANG Y C, et al. Exceptional plasticity in the bulk single-crystalline van der Waals semiconductor InSe. Science, 369(6503): 542. DOI URL
[28]	DENG T T, GAO Z Q, QIU P F, et al. High thermoelectric power factors in plastic/ductile bulk SnSe₂-based crystals. Advanced Materials, 2024, 36(5): 2304219. DOI URL
[29]	KUMAR V, CHANDRA S, SANTOSH R. electronic, First-principles calculations of the structural, elastic and optical properties of LiGaS₂ and LiGaSe₂ semiconductors under different pressures. Journal of Electronic Materials, 2018, 47: 1223. DOI URL
[30]	ZHANG J, LIU G H, CUI W, et al. Plastic deformation in silicon nitride ceramics via bond switching at coherent interfaces. Science, 2022, 378(6618): 371. DOI URL
[31]	LI X C, MENG Y, LI W P, et al. Multislip-enabled morphing of all-inorganic perovskites. Nature Materials, 2023, 22(10): 1175. DOI PMID
[32]	WU Y J, ZHANG Y, WANG X Y, et al. Twisted-layer boron nitride ceramic with high deformability and strength. Nature, 2024, 626: 779. DOI
[33]	LUO J, CHEN J, GAO Z Q, et al. Ductile inorganic ferromagnetic semiconductor. Advanced Materials, 2026, 38(4): e14083.
[34]	LV S Y, LIU X Y, LI X H, et al. Electrochemical peeling few-layer SnSe₂ for high-performance ultrafast photonics. ACS Applied Materials & Interfaces, 2020, 12(38): 43049.
[35]	LIANG J S, WANG T, QIU P F, et al. Flexible thermoelectrics: from silver chalcogenides to full-inorganic devices. Energy & Environmental Science, 2019, 12(10): 2983.
[36]	CHEN H Y, SHAO C L, HUANG S J, et al. High-entropy cubic pseudo-ternary Ag₂(S, Se, Te) materials with excellent ductility and thermoelectric performance. Advanced Energy Materials, 2024, 14(10): 2303473. DOI URL
[37]	CHANG Y, LI Z L, LUO P F, et al. Room-temperature cubic Ag₂S_1-2_xSe_xTe_x with promising ductility and thermoelectric properties enabled by entropy engineering. Advanced Functional Materials, 2024, 34(12): 2310016. DOI URL
[38]	HE S Y, LI Y B, LIU L, et al. Semiconductor glass with superior flexibility and high room temperature thermoelectric performance. Science Advances, 2020, 6(15): eaaz8423.
[39]	WANG Y C, LI A R, HU H P, et al. Reversible room temperature brittle-plastic transition in Ag₂Te_0.6S_0.4 inorganic thermoelectric semiconductor. Advanced Functional Materials, 2023, 33(26): 2300189. DOI URL
[40]	WANG Y C, LI A R, HONG Y R, et al. Iterative sublattice amorphization facilitates exceptional processability in inorganic semiconductors. Nature Materials, 2025, 24: 1545. DOI
[41]	KATO K, HIROSE R, TAKEMOTO M, et al. The RIKEN materials science beamline at SPring-8:towards visualization of electrostatic interaction. AIP Conference Proceedings, 2010, 1234(1): 875.
[42]	PETŘÍČEK V, DUŠEK M, PALATINUS L. Crystallographic computing system JANA2006: general features. Zeitschrift fur Kristallographie-Crystalline Materials, 2014, 229(5): 345.
[43]	THOMPSON P, COX D E, HASTINGS J B. Rietveld refinement of Debye-Scherrer synchrotron X-ray data from Al₂O₃. Journal of Applied Crystallography, 1987, 20(2): 79. DOI URL
[44]	TUCKER M G, KEEN D A, DOVE M T, et al. RMCProfile: reverse Monte Carlo for polycrystalline materials. Journal of Physics: Condensed Matter, 2007, 19(33): 335218. DOI URL
[45]	FARROW C L, JUHAS P, LIU J W, et al. PDFfit2 and PDFgui: computer programs for studying nanostructure in crystals. Journal of Physics: Condensed Matter, 2007, 19(33): 335219.
[46]	LI Z L, ZHANG J Y, LIN C, et al. Origin of ductility in amorphous Ag₂S_0.4Te_0.6. Applied Physics Letters, 2022, 120(7): 073905. DOI URL
[47]	ZHONG S L, BAI H, LUO H, et al. Nature of thermal hysteresis of thermoelectric properties in Ag₂Te_xS_1-_x compounds. ACS Applied Materials & Interfaces, 2024, 16(1): 1148.

Influence of Preparation Processes on the Structure and Properties of the Ductile Thermoelectric Material Ag₂S_0.4Te_0.6

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