Petra Zemenová

Identification of causes of degradation of Gothic ceramic tiles by thermal analyses

Abstract Thermal analyses are suitable methods when studying not only nowadays, but also archaeological ceramic materials. In this case, they were used to study the mineralogical composition and the ageing process of a collection of fragments of Gothic mosaic tiles which were found during archaeological research of Břevnov Benedictine Monastery in Prague. The ceramic bodies of the tiles were differently coloured and showed different degrees of degradation. The ageing process of low-fired ceramics is accompanied by irreversible moisture expansion of a ceramic body which can lead to its degradation. The expansion of ceramic bodies of selected tiles was evaluated by the modified dilatation method. Thermal analyses with the combination of other methods (XRF, XRD and IR) and induced hydrothermal treatment proved the presence of clays in raw materials and helped to identify the causes of different degrees of degradation of the studied tiles.

Phosphate content influence on structural, spectroscopic, and lasing properties of Er,Yb-doped potassium-lanthanum phosphate glasses

Abstract. The influence of the phosphorus pentoxide (P2O5) content on the material properties of Er,Yb-doped potassium-lanthanum phosphate glass was studied. Glass samples of the following nominal composition 35.0K2O-6.8Yb2O3-8.0La2O3-0.2Er2O3-50.0P2O5 (in mol%) were prepared from starting materials mixed with five additional amounts of P2O5 (0, 7.5, 15.0, 30.0, and 45.0 mol% related to the nominal glass composition). The P2O5 addition influence on properties of prepared glasses was studied using Raman, absorption, and fluorescence spectroscopy. The glass residual IR absorption and Judd–Ofelt intensity parameters together with absorption and emission cross sections were estimated. The results showed the increasing polymerization of glass and the P─O bond shortening with P2O5 content increase. The spectroscopy of Er3+ and Yb3+ ions was affected only marginally by the glass composition. It was found that fluorescence decay time corresponding to upper-laser-level I413/2 increased with the decrease of P2O5 content in the glasses, which was related to increasing OH− contamination of the glass. The laser action at 1.53  μm under 975-nm pulsed laser diode pumping was successfully demonstrated. Low threshold and laser slope efficiency up to 21% in respect to absorbed pumping power were obtained.

Phase transitions and crystal structures of η′′-Cu(3+x)Si and η′′′-Cu(3+x)Si

Phase transitions and crystal structures of η’’-Cu(3+x)Si and η’’’-Cu(3+x)Si Cinthia Antunes Correa1,2, Morgane Poupon1, Olivier Pérez2, Robert Král1, Petra Zemenová1, Jérôme Lecourt2, Jaromír Kopeček1, Petr Brázda1, Mariana Klementová1, Lukáš Palatinus1 1Department Of Structure Analysis Institute Of Physics Of The Czech Academy Of, Prague, Czech Republic, 2Department of Physics of Materials, Charles University in Prague, Ke Karlovu 5, Prague 2, Czechia E-mail: cinthiacac@gmail.com