Cross-Doping Agents for Rutile Masers

Abstract

The EPR spectra of nonstoichiometric rutile and rutile doped with tantalum, niobium, and cerium have been examined at helium temperatures. Ta4+ and Nb4+ have short spin-lattice relaxation times and appear to be suitable for cross doping in maser applications.

Optical Absorption by Polarons in Rutile (TiO2) Single Crystals

“…The increase in conductivity from 300 to 600 "K is much more pronounced in samples No. 21 and 23 than in sample No. 15.…”

“…However, in crystals of TiO, doped with Nb studied in this work the impurity atoms are placed in titanium sites in the state Nb4+ according to [21], i.e. their electron configuration is 4d'.…”

“…8) is supposed to be due to a change in the mobility (all donors are ionized, absorption intensity does not depend on temperature), then the faster increase of uo in samples No. 21 and 23 corresponds to an increase in the carrier density. The relative changes of the carrier density with temperature estimated from a, and aM are shown in Fig.…”

Identification of Three Trapping Centers in Calcium Tungstate

“…Further evidence for niobium in the covalent tungsten site was obtained by comparing published ESR data on niobium and vanadium with the corresponding values of niobium from this investigation. h r g e hyperfine separations (309 and 90 G) and negative Agm1-values (-0.151 ; -0.035) are reported for niobium in zircon [18] and rutile [19]. Chu [15] indicates t,hat niobium is in a predominantly ionic site in both those crystal structures.…”

Extended defects in vanadium doped rutile. An EPR and TEM study

“…This technique has been particularly useful to detect and study the presence of ordered and disordered crystallographic shear planes (CSP). However, other techniques such as electrical conductivity measurements [3,4], ESCA [5], and EPR [6] have also been used to advantage in this context. From all this work, it appears [7,8] that at small degrees of reduction (e.g.…”