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CdTe of well-defined composition has been deposited cathodically from an aqueous solution of CdSO4 and TeO2. Films with a rest potential of < --0.3V vs. SCE are n-type, those with a rest potential > --0.3V vs. SCE are p-type semiconductors. The rate of deposition increases with stirring rate; it is proportional to the TeO2 concentration but independent of the CdSO4 concentration. Films deposited at room temperature are amorphous, those deposited at higher temperatures are partly crystalline, the degree of crystallinity increasing with deposition temperature. Grain sizes are in the range 500-1000A. Annealing at 350~ causes the crystallite size to increase to ~0.5 #m.

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The conditions to be met to achieve cathodic deposition of compounds or alloys of well-defined stoichiometric composition are discussed. If the deposition rate constants of the components are of the same order, two classes of codeposition have to be distinguished, differing in whether the difference in electrode potential of the individual components is larger (class I) or smaller (class II) than the shift in electrode po,tential of either component as a result of compound or alloy formation. In the former case the potential of the deposit is determined by the less noble component over the entire composition range, the deposition potential shifting monotonically with composition. In the latter case the role of potential-determining species may shift Irom one component to the other at an intermediate composition, the deposition potential at this composition being more positive than that of either of the components when deposited individually. For class I, quasi rest potentials uniquely characterize the deposits. For class II different deposits may have the same quasi rest potential. Compounds are stable in electrolytes with large concentrations of the normal ions of one of the components in the absence of nonmetal complexes necessary to make cathodic deposition of the compounds possible. If the potential is not determined by adsorbed noncomponent species, the potentials are determined by the normal ions, the concentrations of which are linked by solubility products.Cathodic codeposition of different elements with formation of metallic alloys or compounds from aqueous electrolytes has been known for a long time (1). Nonmetals such as S, So, To, and As and semimetals such as Sb and Bi can be deposited cathodically from solutions of complex ions or molecules (2) and cathodic codeposition of one of these elements and metallic elements with the formation of compounds may therefore also be possible. Examples are found in the formation of CdSe and Ag2.Se (3), Ni-P and Co-P alloys (4), and .Interactions between the components in the deposit usually shift the deposition potential of the deposit to values that are positive relative to the deposition potential of the less noble component (induced codeposition) (6). In some cases, e.g., for Ni, Sn alloys (7), the deposition potential is positive even relative to that of the noble component, an effect that so far remained unexplained (8).In this paper the thermodynamic basis of codeposition and the nature of the potential-determining species are considered and on this basis an explanation of the observed effects is arrived at. No attention is paid to the possibility of hydrogen discharge.

The direct current‐voltage characteristics of symmetrical cells Pt, O2(I), |Zr0.85Ca0.15O1.85|normalPt , O2(II), with pO2false(Ifalse)=pO2false(IIfalse) , were measured at 560°C under oxygen pressures from 1 to 10−20 atm. The characteristics were nonohmic, the deviation from ohmic law being mainly due to the potential drop at the cathode interface between the solid electrolyte and the gas ambient. The characteristics consist of two parts. The first is characterized by a marked oxygen pressure dependence and is observed at voltages lower than approximately 2V (weak polarization). In this range, the rate‐determining process is the diffusion of oxygen atoms (resulting from dissociation of O2 or H2O ) through the platinum of the Pt paste electrode. The second part of the characteristic is almost independent of the oxygen pressure and is observed at voltages higher than approximately 2V (strong polarization). Here the rate‐determining step is the process in which neutral oxygen atoms, adsorbed at the cathode surface of the electrolyte, combine with effectively neutral oxygen vacancies VOx , (oxygen ion vacancies which have trapped two electrons) to form a normal O2− lattice ion false(OOxfalse) . This process utilizes the part of the electrolyte surface not in contact with the platinum, but close to points where the platinum makes contact, and involves migration of electrons from the platinum over the surface of the electrolyte.

It is proposed that the luminescent center in ``self-activated'' ZnS consists of a cation vacancy whose nearest surroundings have lost one electron. Such a center is consistent with the fact that at low firing temperatures, the appearance of the blue fluorescence of self-activated ZnS depends upon the presence of ``promoter ions'' (monovalent anions or trivalent cations) whereas, if the firing temperature be sufficiently high, some blue fluorescence is obtained without the presence of such promoter ions. The luminescence of reduced ZnS, CdS, and ZnO is also discussed, and is attributed to anion vacancies that have trapped one electron.

Electrolytic cells based on stabilized zirconia as a solid electrolyte may be used to remove oxygen from stationary or streaming gas. The minimum pressures (activities) that can be accurately measured are limited by the onset of electronic conduction in the electrolyte. In buffered gases, the lowest pressure that can be attained either by the capacity of the buffer or by the decomposition kinetics of the buffer molecules. Typical values of the oxygen pressures that can be reached when using commercial high‐density sintered stabilized zirconia tubes as an electrolyte, are ≈10−38 normalatm at 530°C , 3×10−30 normalatm at 700°C , and 3×10−27 normalatm at 800°C .