Linkam’s THMSG600 stage is advancing birefringence research in Poland.
Birefringence, a property of a crystalline material, describes how within the material there are two distinct indices of refraction.
Birefringent materials are used to create polarising filters or interference colours. Some familiar birefringent materials include tourmaline, calcite, quartz, ice, and barium titanate (BaTiO3).
Krystian Roleder, a researcher at the Institute of Physics, University of Silesia, has been using the THMSG600 stage to study birefringence in several materials, including BaTiO3.
In this research, Roleder and his colleagues have focused on the materials properties above crystallisation temperature.
Extensive studies have looked at the phase transitions and domain structure along with the optical, electrical and mechanical properties.
It is widely accepted that the Ti ion becomes displaced from its position within the oxygen octahedron, and this is the cause of the polar region formation within the crystal.
It is not fully understood why this displacement occurs. It was found that the BaTiO3 crystals were birefringent over a broad temperature range but disappeared over 160-170°C.
The group has demonstrated the temperature dependence of the birefringence above crystallisation temperature and the behavior of anomalous birefringence can be attributed to the existence of polar clusters.
These polar clusters interrupt the cubic symmetry of the crystal and about crystallisation temperature the crystal become birefringent.
Samples were tested using the THMSG600 stage on an Oxford Cryosystems Metripol Birefringence Imaging System and heated at a constant 0.2°C/min.
The stage gives researchers the option to characterise their sample quickly by heating to within a few degrees of the required temperature at a rate of up to 150°C/min with no overshoot.
They may also modify the temperature ramp to a few tenths of a degree per minute so that they can closely examine the sample for any changes providing the ideal instrument for these studies.
