The sol-gel samples in the doped binary system B2O3-P2O5 were obtained from precursors boron oxide and tri-ethil-phosphate, together with dysprosium and therbium oxides, diluted in ethanol and water. The pH was adjusted by using ammonia and hydrochloric acid. The doped samples were gelified at pH 2 (sample1), 1 (sample 2), 3 (sample 3) and 2.5 (sample 4). The drying treatment took place at 150oC, for 2 hours. The structure and properties of the obtained samples were analyzed by using Raman, FTIR and UV-Vis spectroscopy, thermal analysis and mechanical behavior at nano- and micro - scale under concentrated load action [1]. The structure - properties correlation was studied by using XRD, XRF, SEM-EDS, and AFM measurements. The magneto- optical properties were analyzed using a modified Kerr device [2]. In the case of sample code 4, for dried powder, the thermal behavior is shown in Fig.1 and XRD pattern in Fig. 2.      Fig. 1. TG-DSC analysis for sample4  Fig. 2. XRD pattern for sample 4 (* Hydrogen phosphate; # Phosphorous; + Boric acid; 0 Boron phosphide )  From Thermogravimetric analysis - TG – mass curve (Fig. 1) a total weight loss of about 40 wt% is registered during heating up to 700ºC, most of it (about 35 wt% ) occurring in the temperature range 220-350 ºC, with 3-4 wt% weight loss occurring at 103-108 ºC. Differential scanning calorimetry - DSC curves show several peaks. The sharpest peak occurs at 292-327 ºC, and the peak temperature increases from sample 1 to sample 4. From both curves, it is observed that this sharpest peak in DSC curve is within the temperature range where most of the mass is lost as TG curve shows. An endothermic peak is observed for sample 1 at 235 ºC, and a less sharp one at 250 ºC for sample 2, but it is not observed in curves for samples 3 and 4. Most likely the XRD peaks from Fig. 2 can be identified: Hydrogen phosphate ion (HPO42-) - file 025-0378; Phosphorous (P)-file 002-0266; Boric acid (H3BO3) - file 030-0199 and boron phosphide of form B12P2 - file 048-1166.