Microscope slide collections represent extremely valuable depositories of research material in a natural history, forensic, veterinary, and medical context. Unfortunately, most mounting media of these slides deteriorate over time, with the reason for this not yet understood at all. In this study, Raman spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy, and different types of light microscopy were used to investigate the ageing behaviour of naturally aged slides from museum collections and the experimentally aged media of Canada balsam and Permount™, representing a natural and a synthetic resin, respectively, with both being based on mixtures of various terpenes. Whereas Canada balsam clearly revealed chemical ageing processes, visible as increasing colouration, Permount™ showed physical deterioration recognisable by the increasing number of cracks, which even often impacted a mounted specimen. Noticeable changes to the chemical and physical properties of these mounting media take decades in the case of Canada balsam but just a few years in the case of Permount™. Our results question whether or not Canada balsam should really be regarded as a mounting medium that lasts for centuries, if its increasing degree of polymerisation can lead to a mount which is no longer restorable.

The systems Nb2O5-Ta2O5 and Nb2O5-V2O5 were investigated using thermal analysis, X-ray powder diffraction and thermodynamic simulations. Solid solution formation is possible for both systems; furthermore, both contain one intermediate compound, VNb9O25 or Ta2Nb4O15, respectively. Phase relationships for pure niobium(V)oxide and tantalum(V)-oxide were studied under ambient pressure. It was found that both compounds can occur in two stable solid modifications. For niobium(V)-oxide this are the monoclinic high-temperature modification (H-Nb2O5) and an orthorhombic low-temperature modification (T-Nb2O5) and for tantalum(V)-oxide a tetragonal high-temperature form (alpha-Ta2O5) and an orthorhombic low-temperature form (beta-Ta2O5). Based on these results, crystal growth experiments with various compositions from both systems were carried out using the optical floating zone (OFZ) technique.

High-temperature thermal properties of three neighboring rare-earth scandates DyScO3, TbScO3 and GdScO3 were compared to La0.29Sr0.71Al0.65Ta0.35O3 (LSAT) and sapphire. To calculate thermal conductivity, heat capacity and thermal diffusivity were measured by differential scanning calorimetry and laser flash technique, respectively. DyScO3 and TbScO3 showed an untypical rise in the thermal conductivity above 900 K, while for GdScO3, LSAT and sapphire the expected decrease at elevated temperatures could be observed. (C) 2017 Elsevier B.V. All rights reserved.