Scientists from the University at Albany have created a new chemical compound that could lead to a breakthrough in the field of rocket fuel science. The compound is manganese diboride (MnB₂), which has a significantly higher energy density than conventional solid propellant materials. The use of this fuel could reduce the weight and volume of rocket fuel tanks, freeing up valuable space for scientific equipment or samples to be delivered to Earth.
Diborides, a special class of chemical compounds in which a metal atom is bonded to two boron atoms, first attracted scientific interest in the 1960s. Even back then, theoretical models predicted the unusual properties of these compounds, although practical synthesis remained elusive. In the case of manganese diboride, the researchers would have to not only obtain the substance in pure form but also understand how its unusual atomic structure determines the material’s behavior. For that purpose, an arc furnace was used: pressed powders of manganese and boron were fused at a temperature of about 3,000°C and rapidly cooled, fixing the atoms in a tense asymmetrical state akin to a compressed spring.
To understand the properties of the new material, the researchers built a computer model. The model showed that the atoms in the crystal lattice are arranged with a slight distortion, an effect chemists call strain. This asymmetry is the source of the high energy stored in the material. The researchers refer to a trampoline as a simple analogy: when a heavy weight is placed on a trampoline, it stretches and stores energy, which is released when the weight is removed. By the same principle, igniting manganese diboride releases an enormous amount of energy stored in its asymmetric structure.
Compared to aluminum, which is used in modern solid-fuel boosters, manganese diboride demonstrated significantly higher energy capacity, about 20% greater by mass and 150% greater by volume. Moreover, it ignited only after coming in contact with a special initiator. This means that the material is stable and safe.
Notably, the study was not meant to discover a new fuel: the scientists were trying to produce a material harder than diamond. However, one of the samples behaved differently, starting to heat up and emitting a beautiful orange color. This chance observation prompted the team to explore the energetic properties of the resulting compound, ultimately leading to the discovery of its high energy density and clearly demonstrating how fundamental research can yield practical results that no one had initially imagined.
The potential applications of manganese diboride are not limited to rocket engines. The scientists also see potential in other areas, such as creating more efficient catalysts in automotive catalytic converters and accelerating the decomposition of plastic.
