Effects of Sc, Ti, Hf, V, Nb and Ta doping on the properties of ZrNiSn alloys

• Published in: Journal of materials science Vol. 54; no. 14; pp. 10325 - 10334
• Main Authors: Gong, Bo, Liu, Fusheng, Zhu, Jiaxu, Wang, Xiao, Ao, Weiqin, Zhang, Chaohua, Li, Yu, Li, Junqin, Xie, Heping
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.07.2019; Springer; Springer Nature B.V
• Subjects: Alloys; Carrier density; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Crystallography and Scattering Methods; Diffraction; Dopants; Doping; Electric properties; Electronic Materials; Hafnium; Hardness; Magnetic levitation; Materials Science; Mechanical properties; Microhardness; Niobium; P-type semiconductors; Plasma sintering; Polymer Sciences; Power factor; Room temperature; Scandium; Semiconductors; Smelting; Solid Mechanics; Spark plasma sintering; Tantalum; Thermal conductivity; Thermal stability; Thermoelectricity; Titanium; Vanadium; X-rays; Zirconium
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-019-03623-4

In this study, the effects of three different types of doping elements on the thermoelectric properties, mechanical properties and thermal stability of Zr 0.95 A 0.05 NiSn (A = p-type dopant: Sc; isoelectronic dopants: Zr, Ti and Hf; n-type dopants: V, Nb and Ta) were systematically investigated. The sample was prepared by smelting multiple magnetic suspensions in combination with the spark plasma sintering method. X-ray diffraction analysis and scanning electron microscopy observations showed that nearly single-phase half-Heusler compounds were obtained for the levitation-melted ingots. The results demonstrate that p-type doping causes the semiconductor behavior of this material to change from n type to p type, resulting in poor thermoelectric properties. The mass fluctuations and stress fluctuations introduced by the isoelectronic doping cause the thermal conductivity to decrease, and n-type dopants increase the carrier concentration of the material, resulting in an increase in its power factor. On this basis, the ZT max value of the Zr 0.95 M 0.05 NiSn (M = Ti 0.25 Hf 0.25 Nb 0.25 V 0.25 ) sample reached 0.76, which is 58% higher than that of ZrNiSn within the measurement temperature range. In addition, all of the samples maintained excellent mechanical properties, and their microhardness (HV) was greater than 900; no significant endothermic or exothermic phenomenon of all these samples was observed from room temperature to 700 °C, confirming their good thermal stability.