B. A. Sava, L. Boroica, M. Sava, M. Elisa, C. I. Vasiliu, F. Nastase, C. Nastase, R. Medianu, Potassium phosphate glasses used as agro-fertilizers with controlled solubility, J. Optoelectron. Adv. Mater. 13/11-12 (2011) 1534 – 1541.

Title: Potassium phosphate glasses used as agro-fertilizers with controlled solubility

Abstract:Two series of potassium phosphate glasses have been prepared, AG2 compositions containing P(2)O(5), K(2)O, MgO with B(2)O(3). Fe(2)O(3), ZnO, MoO(3) and AG3 compositions containing P(2)O(5), K(2)O, MgO, CaO with B(2)O(3), Fe(2)O(3), ZnO, MoO(3), MnO(2). The glasses have been prepared by a conventional route: (i) preparation of raw materials; (ii) melting and refining; (iii) fritting; (iv) grinding of the glass; (v) screening of glass powder. Both for AG2 and AG3 glasses, FTIR spectra recorded in the 400-4000 cm(-1) range, revealed optical phonons specific for the phosphate matrix. In the case of AG2.1 and AG3.1 glasses containing B(2)O(3), FTIR spectra put in evidence optical phonons specific for B-O bond from BO(3) and BO(4) units. Raman spectra, recorded in the 100-4000 cm(-1), by 785 nm laser excitation show stretching vibration modes specific for phosphate matrix together with Mg-O vibration mode in the 320-336 cm(-1) range. Information about vitreous fertilizers solubility was achieved by conduct-metric method. For AG2 series, minimum solubility was measured for the sample containing iron oxide and maximum solubility for base sample. From AG3 series, the sample containing iron oxide also showed minimum solubility, but the maximum solubility appeared for the sample with molybdenum oxide.

Key words: Potassium phosphate glass; Fertilizers; Solubility; FTIR; Raman