Compensation modes in counterdoped rutile

Thermogravimetric measurements were conducted on undoped, Nb 5+ or Ta 5+ donor-doped, and Al 3+ acceptor doped rutile at 1000°C and 10 5–10 −7 Pa oxygen activity. Nb 5+ or Ta 5+ doped rutile was counterdoped by Al 3+ in order to identify the role of Al 3+ acceptor and its effect on donor doped rutile. Our results show that both dopants enter the lattice substitutionally for Ti 4+, that Al 3+ is as effective an acceptor as Nb 5+ or that Ta 5+ is effective as a donor, and the compensation occurs on a one-to-one basis. Earlier reports indicate that Al 3+ is at best 50–70% efficient as an acceptor.