<P> Germanium is a semiconductor . Zone refining techniques have led to the production of crystalline germanium for semiconductors that has an impurity of only one part in 10, making it one of the purest materials ever obtained . The first metallic material discovered (in 2005) to become a superconductor in the presence of an extremely strong electromagnetic field was an alloy of germanium, uranium, and rhodium . </P> <P> Pure germanium suffers from the forming of whiskers by spontaneous screw dislocations . If a whisker grows long enough to touch another part of the assembly or a metallic packaging, it can effectively shunt out a p-n junction . This is one of the primary reasons for the failure of old germanium diodes and transistors . </P> <P> Elemental germanium oxidizes slowly to GeO at 250 ° C. Germanium is insoluble in dilute acids and alkalis but dissolves slowly in hot concentrated sulfuric and nitric acids and reacts violently with molten alkalis to produce germanates ((GeO). Germanium occurs mostly in the oxidation state + 4 although many + 2 compounds are known . Other oxidation states are rare: + 3 is found in compounds such as Ge Cl, and + 3 and + 1 are found on the surface of oxides, or negative oxidation states in germanes, such as − 4 in GeH . Germanium cluster anions (Zintl ions) such as Ge, Ge, Ge, ((Ge)) have been prepared by the extraction from alloys containing alkali metals and germanium in liquid ammonia in the presence of ethylenediamine or a cryptand . The oxidation states of the element in these ions are not integers--similar to the ozonides O . </P> <P> Two oxides of germanium are known: germanium dioxide (GeO, germania) and germanium monoxide, (GeO). The dioxide, GeO can be obtained by roasting germanium disulfide (GeS), and is a white powder that is only slightly soluble in water but reacts with alkalis to form germanates . The monoxide, germanous oxide, can be obtained by the high temperature reaction of GeO with Ge metal . The dioxide (and the related oxides and germanates) exhibits the unusual property of having a high refractive index for visible light, but transparency to infrared light . Bismuth germanate, Bi Ge O, (BGO) is used as a scintillator . </P>

What is the oxidation state of ge in geh4
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