Calcium nitrate ca no3 2

Altered microwave-stimulated hydrothermal method proposed by D. Karthickraja et al. [29 (link)] was applied to obtain the nHAp/IO composite. Initially, 20 mL of a water suspension of 0.3000 g (1.3 mmol) of iron oxide (IO) and 1.0647 g (8.06 mmol, 3-fold excess relative to the calcium ion concentration) of diammonium hydrogen phosphate ((NH₄)₂HPO₄, Acros Organics, Geel, Belgium, 98+%) was sonicated for 15 min. Afterwards, 5 mL of ammonia (25%) was added to the mixture to obtain alkaline environment. Then, 25 mL of water solution of 1.0577 g (4.48 mmol) of calcium nitrate (Ca(NO₃)₂, Sigma-Aldrich, St. Louis, MO, USA, > 99%) and 0.1721 g (0.08 mmol) of citric acid (C₆H₈O₇, Alfa Aesar, Haverhill, MA, USA, 99+%) were added, and the mixture was sonicated for 10 min. Subsequently, the obtained suspension was transferred to the Teflon vessel and put into a microwave reactor (Magnum II, ERTEC-Poland, Wrocław, Poland) under the pressure of 20–30 atm at 200 °C for 90 min. Finally, the synthesized product was washed with deionized water to remove the by-products and further dried at 70 °C for 24 h.

The silicon preceramic polymer used in this study is Loctite 5248
(AG & Co., Germany, Henkel), a UV-curable alkoxy silicone with
thixotropic behavior and a viscosity range of 50–80 cP at 25
°C. The Si/O/C ratio calculated by XPS spectra was 19:27:54 (see
Figure S1 in the Supporting Information), while the number-average molecular weight was = 55 kDa, as measured from static light scattering analysis (SLS,
Zetasizer Nano ZEN3600, Malvern Instruments). Loctite 5248, which
is a straw-colored one-component liquid solution, was directly dissolved
in ethyl acetate (vapor pressure = 73 mmHg at 20 °C; Sigma-Aldrich)
to prepare BFTSA precursor solutions at 2 and 5% w/v (mg/mL). The
solution was stirred overnight at room temperature and wrapped into
an aluminum foil to prevent curing from ambient light. Double-side
mechanically polished Ti6Al4V discs of a diameter of 10 mm and a thickness
of 2 mm (provided by Eurocoating SpA, Italy) were used as substrates.
Calcium nitrate, Ca(NO₃)₂ (Sigma-Aldrich, USA);
diammonium phosphate, (NH₄)₂HPO₄ (Sigma-Aldrich,
USA); gelatin from cold water fish skin (Sigma-Aldrich, USA); deionized
(DI) water; and ammonium hydroxide (28%, Millipore, USA) were used
to synthesize HAp NPs.