Ultrafast Synthesis and Thermoelectric Properties of Mn_1+xTe Compounds

Abstract

MnTe compounds show great potential for thermoelectric applications in the intermediate temperature range (500-800 K) because of their large Seebeck coefficient and intrinsically low thermal conductivity. So far, the existing methods for the synthesis of MnTe compounds remain constrained to multistep processes that are time- and energy-intensive. Herein, we demonstrate ultrafast synthesis of high-density bulk MnTe compounds using a combination of self-propagating high-temperature synthesis (SHS) and plasma activated sintering. The entire synthesis and processing procedure takes less than 1 h. The thermodynamic consideration suggests that the SHS process includes two steps: (1) Mn + 2Te → MnTe + Q and (2) MnTe → MnTe + Te. With the heat released by step (1), the process moved in cycle and finished in a rather short time. The effect of extra Mn content on the structure and thermoelectric properties was investigated. There is some solubility limit of extra Mn in the MnTe compound. The extra Mn occupy interstitial sites, leading to a decrease of carrier concentration while enhancing Seebeck coefficient and decreasing thermal conductivity. Low-temperature heat capacity data indicates that the MnTe compound has a high effective mass of 8.34 m and a low Debye temperature of 186 K, which are beneficial for the large Seebeck coefficient and low thermal conductivity. Therefore, the maximum ZT value reaches 0.57 at 850 K for the MnTe compound.

Ultralow Thermal Conductivity and High Thermoelectric Performance in AgCuTe1–xSex through Isoelectronic Substitution

“…Thermal stability was determined by a thermogravimetric analysis technique (TG, STA 449F3, Jupiter) in an open alumina crucible, and high-purity nitrogen was used as the purge gas. Heat flow was determined by a differential scanning calorimeter (DSC Q20, TA Instruments) under a nitrogen atmosphere from RT to 773 K. It is noteworthy that the accuracies in the above S , σ, and κ values refer to ±5, ±3, ±4%, respectively, and error in ZT is estimated to be ∼11% …”

“…Heat flow was determined by a differential scanning calorimeter (DSC Q20, TA Instruments) under a nitrogen atmosphere from RT to 773 K. It is noteworthy that the accuracies in the above S, σ, and κ values refer to ±5, ±3, ±4%, respectively, and error in ZT is estimated to be ∼11%. 31 3. RESULTS AND DISCUSSION 3.1.…”

Significant Enhancement in the Thermoelectric Performance of Aluminum-Doped ZnO Tuned by Pore Structure

“…Thermal diffusivity was measured at 27–500 °C by the laser flash measurement system (LFA-457, Netzsch). The uncertainties in electrical conductivity, Seebeck coefficient, and thermal conductivity are ±3, ±5, and ±4%, respectively . The relative bulk density was measured by the ratio of mass to volume.…”

Thermoelectric, Magnetic, and Mechanical Characteristics of Antiferromagnetic Manganese Telluride Reinforced with Graphene Nanoplates

“…The Mn reaction with carbon consumes Mn, leading to Te-rich domains that favor the formation of MnTe 2 , as confirmed by the XRD peak at 2θ ¼ 32 ( Figure 3). The formation of the MnTe 2 phase can be explained by thermodynamic considerations [73,74] based on three reaction steps for the formation of MnTe alloy in the current study: 1) 2Mnþ2Te ! MnTe 2 þMnþ Q 1 @ mechanical alloying and milling (MnTe 2 standard heat of formation ¼ À26.4 kcal mol À1 ); [75] 2) MnTe 2 !…”