The crystal lets current flow in both directions, acting in one case like a normal diode but when certain conditions change, it can act like a reversible diode. Traditional semiconductor diodes have only one current flow direction and are not reversible. This capability makes the crystal so special.
The crystal is a ferroelectric material which exhibits electrical polarization. This polarizations is known as “bulk effect”. “This could make computer chip designs more flexible,” said Sang-Wook Cheong, physics professor.
The material is part of the crystalline class known as perovskites.
Perovskites have two positive ions bound to negative ions. The two positive ions, bismuth and iron have different atomic sizes. The negative ions come from oxygen.
But this is not all as the ferroelectric material has another important property: It seems to be very sensitive to light. The diodes made from this material are able to generate current while exposed to light. This property is very important as the material can be used to increase solar cell efficiency.