(3) So far, MAX phases are studied as either bulk materials or thin films and are prepared by traditional and nonconventional solid-state synthesis techniques (6) and thick-film methods, respectively.
(1−5) Specifically, their machinability compared to existing materials is heavily beneficial and dramatically increases the variety of potential applications. The unique combination of both metallic and ceramic properties enables them to be viable materials in high-temperature and high-pressure environments. They consist of early transition metals (M), main group elements (A), and carbon/nitrogen (X), with the general composition of M n+1AX n ( n = 1, 2, 3, and rarely 4) crystallizing in space group P6 3/ mmc. MAX phases, a class of layered ternary carbides and nitrides, attract increased scientific interest because of their intriguing properties, for example high-temperature and corrosion resistance and metallic conductivity. We demonstrate for the first time how our wet chemical synthesis strategy immensely increases the accessibility of specific shapes and morphologies via the targeted synthesis of thick films, microspheres, and hollow microspheres. Here, a facile and versatile sol–gel-based approach for the biopolymer-templated synthesis of MAX phase Cr 2GaC is introduced, capable of preparing the layered ternary carbide in a variety of technological useful shapes. In fact, MAX phases are typically studied in either bulk or thin films, considerably hindering their integration into highly functional applications. This is particularly odd considering their existence of more than 60 years, however, less so considering the common synthesis techniques used.
Although many potential areas of application have been identified, a commercialization is still to be realized. The class of MAX phases represents intriguing materials, as they combine ceramic and metallic properties quite exotically.