W. B. Westphal

Protons, dipoles, and charge carriers in rutile in rutile☆

Abstract After a short discussion of structure and infrared-vibration data of rutile (Section 1), the presence of protons, replaceable by deuterons, is determined by the OH and OD stretching vibration and traced to specific lattice sites (Section 2). Various reactions in hydrogen and oxygen (Section 3) and the effects of reduction on electron mobilization and the optical absorption spectrum are considered (Section 4). Absorption spectra at high temperature and quenching experiments clarify the interrelation between absorption spectra, vacancies and conductivity (Section 5). Space-charge polarization and blocking-layer effects are elucidated by dielectric relaxation spectra, discharge characteristics and the influence of prehistory and addition agents (Section 6). Electron injection into the empty conduction band transforms unreduced rutile from an insulator into a very good conductor; incandescence and thermal breakdown at low voltage results; impulse voltage produces much higher electric strength (Section 7). All observations show the extremely anisotropic conduction of unreduced rutile single crystals, with preference by orders of magnitude in the optic-axis direction, as expected from the crystal structure. This preference is being systematically destroyed by progressive reduction. Rutile is both an n - and a p -type conductor; the experiments here reported together with the facts known previously lead to a consistent picture of its properties (Section 8).

Transfer of Protons through “Pure” Ice Ih Single Crystals. I. Polarization Spectra of Ice Ih

After a short introduction of the subject “proton transfer in ice” and some background information on previous polarization measurements, the growing and preparation of our single crystals and the instrumentation for a–c measurements from 105–8 × 10−3 Hz, 0 to − 180°C, are briefly described. By rigorous control of error limits and an improved computerized evaluation procedure it was possible to resolve the dielectric spectrum of these “pure” ice single crystals into several significant components: the intrinsic Debye spectrum, two weak spectra preceding it at a high frequency, and “space‐charge‐polarization” spectra. Important characteristics of these spectra and inherent difficulties in quoting their “accurate” parameters are presented. The interpretation of these data requires new molecular models; they are developed in Part II; the analysis of polarization data is resumed in Part III in conjunction with new transconductance measurements.

Transfer of Protons through “Pure” Ice Ih Single Crystals. III. Extrinsic versus Intrinsic Polarization; Surface versus Volume Conduction

In order to analyze the charge transport through ice Ih single crystals and over their surfaces, the a–c polarization studies of Part I were supplemented by d–c and transient measurements ranging from 10−2‐4 × 104 V/cm, from nanoamperes to microamperes, and from 100μsec–3 h. After a brief description of techniques, the research focuses on “conductivity” as represented by an activation energy equation. In the literature, the activation energies quoted range from 33 ↔ 0 kcal/mole. Investigating the reasons for this confusion we found: (1) The value 33 kcal/mole is caused by surface conduction and can be reduced to ∼ 20 kcal/mole by pumping. (2) Zero activation energy characterizes the “initial” currents in the milli‐second range. (3) Intermediate values (e.g., 12 kcal/mole) stem from apparent conductivities in space‐charge distorted fields. The saturation current at high fields, measured by Eigen and co‐workers (activation energy ∼ 22 kcal/mole), seems to be an extrinsic current produced by multicrystallini...

Dispersion and absorption in ferromagnetic semiconductors

A broad-band spectral analysis was undertaken of the dielectric properties of ferrites (polarization, magnetization and conduction) from d.c. to the optical spectral region. After a short description of the various measurement techniques employed, characteristic data are given of electronic conduction, space-charge polarization, infrared absorption, and ferromagnetic resonance. Various additional resonance and relaxation effects are discussed, which, in addition, may shape the very complicated frequency-response characteristics. The effect of structure and cation distribution of the ferromagnetic semiconductors on the electric and magnetic properties are also considered.