What type of material are the semiconductor blocks in a lightning arrestor made from?

The semiconductor blocks in a lightning arrestor are primarily made from zinc oxide. This material is chosen because of its excellent electrical properties, which enable it to effectively manage high voltages and provide superior protection against electrical surges caused by lightning strikes.

Zinc oxide is known for its non-linear voltage-current characteristics, which means its resistance decreases dramatically under high voltage conditions. This allows it to clamp voltage spikes quickly and divert excess energy away from sensitive equipment. The robustness and reliability of zinc oxide make it highly suitable for use in arrestors, ensuring effective performance over an extended period.

Other materials listed, while useful in electrical applications, do not have the same non-linear properties or high-voltage handling capabilities that are necessary for lightning protection devices. Silicon, aluminum, and copper may play vital roles in various components of electrical systems, but they do not exhibit the same level of effectiveness for the specific application in lightning arrestors as zinc oxide does.