V028 and V029 are a combination of the refractory metal tungsten and an alumina barrier (Al2O3) coating over the tab area. The exposed metal area comprising the bottom of the boat allows the sample to be in good thermal contact with the source. The barrier will tend to help concentrate the heat towards the center. The alumina barrier will inhibit an evaporant (if used as a sample instead of an aperture) from creeping toward the heat sink or from wetting the entire boat.
V028: Boat 82.5 x 12.7mm, trough 19 x 6.3 x 2.4mm deep.
V039: Boat 101.6 x 25.4mm, trough 44.5 x 16 x 2.4mm deep.
V030 replaces alumina crucibles for some specific applications. Good heat transfer yet has alumina inertness. Evaporant does not wet the alumina: no resistant change of the boat when evaporant melts. Due to the non-wetting characteristic, the evaporant forms a sphere when melted, resulting in a point source.
Boat 101.6 x 12.7mm, dimple Ø 12.7 x 3.2mm deep.
Melting point of tungsten boats with coated Al2O3 tabs: 3422 deg. C.