Window member for an x-ray device

A method for forming a window member for separating an internal environment of an x-ray device from an environment external to the x-ray device, the method comprising:

• providing a window member comprising a substrate having a first surface and a second surface opposite the first surface, and a coating layer having a first surface and a second surface opposite the first surface, wherein the substrate is closer to the internal environment than the coating layer, and the coating layer is closer to the external environment than the substrate, wherein the first surface of the substrate faces the internal environment, the second surface of the substrate faces the first surface of the coating layer, and the second surface of the coating layer faces the external environment, wherein the coating layer is disposed upon the second surface of the substrate by way of atomic layer deposition, and wherein:
• the substrate is formed from a polycrystalline material and is substantially transparent to low-energy x-rays;
• and
• the coating layer is non-porous, covers the crystal grains at the second surface of the substrate and extends into the grain boundaries therebetween, such that the coating layer forms an impermeable barrier between the substrate and the external environment.