Diamond is the hardest material in existence but is useless for cutting steel because it reacts with iron , from which steel is made , at high temperatures . Cubic boron nitride , a synthetic material , is the second hardest substance after diamond but is chemically stable against iron at high temperatures .
A desirable composite of diamond and cubic boron nitride crystals could be a unique machining tool that can be developed for work on hard rock and substances that contain iron .
Also , a better understanding of the bonds formed between these two unique semiconducting materials could lead to the development of new types of semiconductors . The nature of these bonds was previously unknown . A team of Japanese researchers from Tohoku University , the National Institute for Materials Science and the Japan Fine Ceramics Centre , collectively made this innovation . They published their findings in Nature Communications .