GB1258307A - - Google Patents

Abstract

1,258,307. Electron multipliers; electrode materials. MURATA MFG CO. Ltd. 26 March, 1969 [29 March, 1968 (2)], No. 15866/69. Heading H1D. An electron multiplying device is constituted by a moulded body 20 of a barium titanate system semi-conductor ceramic, which material is itself secondary electron-emissive, the body having at least one hole 23 therethrough provided with conductive material 21, 22 at each end to form two electrodes. The barium titanate system semi-conductor ceramic is produced by sintering in an inert or reductive atmosphere a composition comprising barium titanate which may contain a rare earth element or an element having a valency of not less than five, e.g. Ta or W. At its temperature of operation the ceramic material should have a positive or zero resistancetemperature characteristic, and an example is given having the following composition- Ba 0À828 Sr 0À170 Ce 0À002 Ti 0À830 Sn 0À170 O 3 . The moulded body may be in the form of a single elongated tube of, for example, circular, triangular, hexagonal or other polygonal cross-sectional shape. A number of such bodies may be stacked together and any gap 24 between them also acts as an electron multiplying channel, and using octagonal shaped bodies with every second side arc-shaped, Fig. 5 (not shown), this channel may be the same size as the hole. A bundle of such bodies may also be twisted together to increase the secondary-emissive path length for a composite body of given width. Alternatively a number of holes may be bored in a large single body of the ceramics material. Suitable electrode materials are conductive silver or carbon paint, indium-gallium alloy, chemically plated nickel, tin or aluminium film or baked silver. The electron multiplying device may be used as one element in an image intensifier tube.