Synthesis and Study of Physical Properties of New Single Crystals of (Bi₂Te₃)1-xLaₓ Solid Solution

In the present study, bismuth telluride (Bi₂Te₃) was selected as the base material due to its well-known thermoelectric characteristics. This semiconductor compound plays a crucial role in applications such as energy conversion, cooling technologies, and waste heat recovery systems. Lanthanum is a rare-earth element. To enhance its functional properties, lanthanum (La) was introduced into the Bi₂Te₃ matrix, forming (Bi₂Te₃)1-xLaₓ solid solutions. It is an interesting and promising area of research in the field of obtaining single-crystal thermoelectric materials. The investigation of such doped single crystals represents a promising direction for improving thermoelectric efficiency. Lanthanum (La) has been widely employed as a dopant to optimize carrier concentration, modify the crystal lattice, and improve the thermoelectric performance of Bi₂Te₃-based materials. A detailed analysis of the (Bi₂Te₃)1-xLaₓ system was carried out, including the construction of phase diagrams. It was established that within the composition range x = 0.01–0.05, a solid solution region based on Bi₂Te₃ exists at room temperature. Additionally, a eutectic interaction between Bi₂Te₃ and La was identified at approximately 15 at.% La with a temperature close to 440 °C. Lanthanum doping resulted in measurable changes in the physical properties of Bi₂Te₃ single crystals. The results demonstrate that lanthanum incorporation yields single crystals with enhanced thermoelectric and galvanomagnetic properties, making them attractive for advanced material applications.