Reference

Reaction ammonium hydrogen phosphate with calcium carbonate during heating

Reaction ammonium hydrogen phosphate with calcium carbonate during heating. Millere, I.; Bielis, I.; Krastina, G. L. (USSR). Uch. Zap., Latv. Gos. Univ., 203, 115-23 (Russian) 1974. CODEN: UZLUA2. DOCUMENT TYPE: Journal CA Section: 57 (Ceramics) Section cross-reference(s): 67 CP (NH4)2HPO4 and CaCO3 were reacted at 190-850.degree.. The CaO content (related to P2O5) was 10-90%. A weak endothermic effect was obsd. on all DTA curves at 110-120.degree. which was caused by a gradual detaching of 1 mol NH4. In the reaction, CaHPO4 [7757-93-9] and Ca(HP2O6)2 [64540-03-0] formed at 190.degree. and Ca(PO3)2 [13477-39-9] formed at 350-500.degree.. The mixts. contg. 60-90% CaO and heated to 620.degree. formed .beta.-Ca2P2O7 [7790-76-3]. In mixts. contg. .ltoreq.50% CaO, Ca(PO3)2 was retained even at .ltoreq. 850.degree., while in the mixts. contg. 70-90% CaO, the .beta.-Ca3(PO4)2 [7758-87-4] was formed.

Thermal behavior of bone and synthetic hydroxylapatites submitted to magnesium interaction in aqueous medium

Thermal behavior of bone and synthetic hydroxylapatites submitted to magnesium interaction in aqueous medium. Baravelli, S.; Bigi, A.; Ripamonti, A.; Roveri, N.; Foresti, E. (Ist. Chim. 7757-93-9 and 7439-95-4 are cas registry numbers. These chemicals are also mentioned in this article. "G. Ciamician", Univ. Bologna, Bologna 40126, Italy). J. Inorg. Biochem., 20(1), 1-12 (English) 1984. CODEN: JIBIDJ. ISSN: 0162-0134. DOCUMENT TYPE: Journal CA Section: 13 (Mammalian Biochemistry) The thermal behavior of the products obtained from Mg2+ interaction with powd. femoral bone and carbonate-contg. synthetic hydroxylapatite under conditions of varying pH in aq. medium was investigated. The products were heat treated at 100-1300° and were characterized by IR spectroscopy and x-ray diffraction techniques. The results show that the interaction with Mg2+ destabilizes the apatitic structure and favors its thermal conversion into b-tricalcium phosphate. The replacement of Mg with Ca in the b-tricalcium phosphate crystal lattice hinders its subsequent thermal conversion into the a form. The influence of Mg on the thermal stability is much more evident for carbonate-contg. synthetic hydroxylapatite than for bone apatite. .