DETAILED DESCRIPTION What is claimed is: 1.
In a method for producing a voltage dependent resistor consisting mainly of a sintered body of zinc oxide and about 0.
1-10% by weight of bismuth oxide in which, there is optionally present, small quantities of oxides of other metals and which body is provided, at opposite faces thereof, with ohmic electrodes, wherein the improvement comprises sintering a mixture of zinc oxide and oxides of metals which may be optionally present, at a temperature of between about 900.
degree.
C - 1450.
degree.
C, in an atmosphere containing bismuth oxide to produce a sintered body and then applying the ohmic electrodes to the resultant sintered body.
2.
The method of claim 1 wherein the atmosphere is an oxidizing atmosphere in contact with molten bismuth oxide.
3.
A voltage dependent resistor obtained according to claim 1.
Description:
The invention relates to a method for producing a voltage dependent resistor mainly consisting of a sintered body of zinc oxide and bismuth oxide in which small quantities of oxide of one or more other metals may have been incorporated and which is provided with ohmic electrodes at two opposite faces of the body and to a voltage dependent resistor obtained according to this method.
The said other metals may, for example be: aluminium, antimony, barium, borium, calcium, chromium, indium, cobalt, copper, manganese, molybdenum, nickel, strontium, tantalum, tin, titanium, iron.
The ohmic electrodes at the opposite faces of the sintered body may consist of thin films of, for example silver, copper, aluminium, nickel-chromium.
In a known method these voltage dependent resistors are obtained by first producing a body from a mixture of zinc oxide and one or more oxides of the other said metals, bismuth oxide excepted.
Thereafter a paste which mainly consists of bismuth oxide is applied to this body, and the body is sintered in an oxidizing atmosphere, usually in air.
Bismuth ions are then diffused in the sintered body.
This method has the drawback that it consists of two steps, the second step being particularly labour-intensive and difficult to reproduce
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