Those studies showed that sulfate minerals such as anhydrate
, gypsum, and alunite are precipitated by reacting with S[O.sub.2] when Ca-rich minerals such as calcite and anorthite are present, which decreases the porosity of the rocks.
calcium silicate of alite and belite phases, detected in initially set materials at =940, 515, and 456 [cm.sup.-1] , decreased and shifted to 996, 524, and 449 [cm.sup.-1], respectively.
This technique is usually based on the use of mixtures of calcium carbonate (CaC[O.sub.3]) and dicalcium phosphate anhydrate
(CaHP[O.sub.4]) (Ca/P ratio of 2), followed by heating at 1450-1500[degrees]C for 6-12 h.
Concentration of calcium and phosphorus in inorganic sources of calcium Source Calcium (%) Phosphorus (%) Calcium carbonate (1) 38.5 0.02 Calcium chloride (2), anhydrate
36.0 -- Calcium chloride (2), dihydrate 27.0 -- Calcium sulphate (2), anhydrate
29.0 -- Calcium sulphate (2), dihydrate 23.0 -- Dolomite limestone (2) 22.0 -- Ground limestone (1) 35.8 0.01 Monocalcium phosphate (1) 16.9 21.5 Dicalcium phosphate (1) 24.8 18.8 Tricalcium phosphate (1) 34.2 17.7 (1) National Research Council, 2012.
Although ZPP forms a mono-hydrate crystal (Zn([O.sub.3][PC.sub.6][H.sub.5])*[H.sub,2]O) in moist air, ZPP anhydrate
(Zn([O.sub.3][PC.sub.6][H.sub.5])) was used in the experiment.
The use of [beta]-cyclodextrin anhydrate
and hydrate," Pharmaceutical Research, vol.
Before analyzing the crystal using powder XRD, the hydrate of the crystal was removed by gravimetric method to produce anhydrate
The first and second peaks of pH value were associated with the appearance of dicalcium phosphate anhydrate
(CaHP[O.sub.4], DCPA) and fibrous OCP ([Ca.sub.8][H.sub.2][(P[O.sub.4]).sub.6]) respectively, and the last stage corresponded to the phase transition of the precursors into HAp powder.