ICB method of forming high refractive index films

A uniform film of sapphire and tungsten is deposited onto a surface of a substrate using the ionized cluster beam ("ICB") apparatus. During ICB deposition, a tungsten crucible containing sapphire is heated until a vapor of sapphire and tungsten is formed. The tungsten crucible is heated to form a tungsten vapor, which causes the crucible material to mix with the sapphire, thereby forming a vapor mixture of sapphire and tungsten. The vapor is ejected through a small nozzle into a vacuum region. The resulting adiabatic expansion of the vapor promotes formation of atomic clusters. Some of the clusters are ionized, and electrons are stripped off the clusters. The clusters are accelerated toward the substrate, which is also within the vacuum region. The clusters impact the surface of the substrate, where they are deposited to form the uniform sapphire/tungsten film. The film is deposited in an sapphire (aluminum oxide)/tungsten ratio of 2:1. The film has a relatively high index of refraction of approximately 2.2, thereby rendering it useful as an optical coating (specifically, an electrochromic material). The film may also be used as a resistive or thermally conductive material.