Metalloid for carbon in steel casting. Of the non-metallic elements less often recognised as metalloids, selenium—in the form of ferroselenium (50–58% selenium)—is used to improve the machinability of stainless steels. All six of the elements commonly recognised as metalloids have toxic, dietary or medicinal properties. Arsenic and antimony compounds are especially toxic; boron, silicon, and possibly arsenic, are essential trace elements. Boron, silicon, arsenic, and antimony have medical applications, and germanium and tellurium are thought to have potential. Boron is used in insecticides and herbicides. It is an essential trace element. As boric acid, it has antiseptic, antifungal, and antiviral properties.
Boron arsenide Boron arsenide Boron arsenide is a chemical compound involving boron and arsenic, usually with a chemical formula BAs. Other boron arsenide compounds are known, such as the subarsenide BAs. Chemical synthesis of cubic BAs is very challenging and its single crystal forms usually have defects. BAs is a cubic (sphalerite) semiconductor in the III-V family with a lattice constant of 0.4777 nm and an indirect band gap of approximately 1.86 eV. It can be alloyed with gallium arsenide to produce ternary and quaternary semiconductors. Cubic BAs is reported to decompose to the subarsenide BAs at temperatures above 920 °C. Boron