Off-stoichiometry effects on the thermoelectric properties of Cu2+δSe (−0.1 ≤ δ ≤ 0.05) compounds synthesized by a high-pressure and high-temperature method. Issue 4 (20th December 2019)

• Record Type: Journal Article
• Authors: Xue, Lisha; Shen, Weixia; Zhang, Zhuangfei; Shen, Manjie; Ji, Wenting; Fang, Chao; Zhang, Yuewen; Jia, Xiaopeng
• Is Part Of: CrystEngComm. Volume 22:Issue 4(2020)
• Page Start: 695
• Page End: 700
• Publication Date: 2019-12-20
• Subjects: Crystals -- Periodicals; Crystal growth -- Periodicals; Crystallography -- Periodicals; Cristaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Cristallographie -- Périodiques; 548
• DOI: 10.1039/c9ce01651a
• Languages: English
• ISSNs: 1466-8033

Abstract

Abstract : The chemical composition can directly tune the transport properties of Cu2 Se liquid-like materials, including the carrier concentration, carrier mobility and superionic feature. Abstract : The chemical composition can directly tune the transport properties of Cu2 Se liquid-like materials, including the carrier concentration, carrier mobility and superionic feature. In this work, the off-stoichiometry effects of both the deficiency and excess of Cu on the phase transition and thermoelectric properties of Cu2+ δ Se (−0.1 ≤ δ ≤ 0.05) compounds are investigated. The Cu2+ δ Se samples were synthesized by a high-pressure and high-temperature (HPHT) technique in 30 minutes. Cu2+ δ Se (−0.1 ≤ δ < 0) existed as a mixture of the monoclinic α-Cu2 Se phase and cubic β-Cu2 Se phase at room temperature, while only the monoclinic α-Cu2 Se phase was detected in the Cu2+ δ Se (0 ≤ δ ≤ 0.05) compounds. Increasing the Cu content can effectively regulate the carrier concentration and reduce the thermal conductivity from 1.45 W m −1 K −1 ( δ = −0.1) to 0.47 W m −1 K −1 ( δ = 0.05) at 843 K. The ultralow lattice thermal conductivity of 0.3 W m −1 K −1 was achieved for Cu1.97 Se and Cu2.0 Se by stoichiometry tuning. A maximum zT value of 1.46 at 843 K was obtained for Cu2.0 Se, which is 100% higher than that of Cu1.9 Se. This work demonstrates the potential of off-stoichiometry for tuning the TE properties of Ag + and Cu + based superionic materials.