On the Crystallization of Terbium Aluminium Garnet

TL;DR

This paper investigates the growth limitations of terbium aluminium garnet (TAG) crystals via the Czochralski method, revealing that TAG melts incongruently and is overshadowed by the more stable TAP phase, hindering large crystal formation.

Contribution

It provides new insights into the phase behavior and melting points in the Tb-Al-O system, explaining why large TAG crystals are difficult to grow.

Findings

TAG melts incongruently at 1840°C

TAP has a congruent melting point at 1930°C

Primary crystallization of TAP suppresses TAG growth

Abstract

Attempts to grow terbium aluminium garnet (Tb3Al5O12, TAG) by the Czochralski method lead to crystals of millimeter scale. Larger crystals could not be obtained. DTA measurements within the binary system showed that TAG melts incongruently at 1840 deg. C. The perovskite (TbAlO3, TAP) with a congruent melting point of 1930 deg. C is the most stable phase in this system. The region for primary crystallization of TAP covers the chemical composition of TAG and suppresses the primary crystallization of the terbium aluminium garnet.