In inorganic chemistry, a Nowotny chimney ladder phase is a particular intermetallic crystal structure found with certain binary compounds. NLC phases are generally tetragonal and are composed of two separate sublattices. The first is a tetragonal array of transition metal atoms, generally from group 4 through group 9 of the periodic table. Contained within this array of transition metal atoms is a second network of main group atoms, typically from group 13 or group 14. The transition metal atoms form a chimney with helical zigzag chain. The main-group elements form a ladder spiraling around the transition metal helix.