ABSTRACT
An efficient application of a material is only possible if we know its physical and chemical properties, which is frequently obstructed by the presence of micro- or macroscopic inclusions of secondary phases. While sometimes a sophisticated synthesis route can address this issue, often obtaining pure material is not possible. One example is TaGeIr, which has highly sample-dependent properties resulting from the presence of several impurity phases, which influence electronic transport in the material. The effect of these minority phases was avoided by manufacturing, with the help of focused-ion-beam, a µm-scale device containing only one phase-TaGeIr. This work provides evidence for intrinsic semiconducting behavior of TaGeIr and serves as an example of selective single-domain device manufacturing. This approach gives a unique access to the properties of compounds that cannot be synthesized in single-phase form, sparing costly and time-consuming synthesis efforts.
ABSTRACT
The spark-plasma-sintering (SPS) technique has successfully been applied for the single-step direct synthesis of Ti2O3 from a mixture of powders of rutile/anatase with titanium. The components react by diffusion through the grain boundaries, forming several intermediate phases locally. A single-phase material of titanium(III) oxide is obtained in compact bulk form after 180 min of SPS treatment at 1473 K. The electrical and thermal transport properties of such a SPS-prepared material measured in the temperature range between 300 and 800 K reflect the known semiconductor-to-metal transition above 400 K. The observed metallic-like electrical and thermal conductivity above this temperature is in good agreement with previously reported results. A maximum of the thermoelectric figure-of-merit ZT = 0.04 is achieved at 350 K.
