Influence of B2O3 on the structure and crystallization of soil active glasses

Glasses of the SiO 2 –P 2 O 5 –K 2 O–MgO–CaO–B 2 O 3 system acting as nutrients carriers in the soil environment were synthesised by the melt-quenching technique. Thermal properties were studied using DTA/DSC methods and the influence of B 2 O 3 and P 2 O 5 content on thermal stability and crystallization process of these glasses was examined. The structure of the glass network was characterized by FTIR, 31 P, and 11 B MAS NMR. The chemical activity of the glasses in the 2 mass% citric acid solution was measured by the ICP-AES method. The analysis indicated that the formation of P–O–B units with chemically stable tetrahedral borate groups decreases the glass solubility in conditions simulating the soil environment.