Synthesis and Mechanism of Tetracalcium Phosphate from Nanocrystalline Precursor

Table 2

Raman shift [cm⁻¹] of the calcinations samples by different cooling methods.

	1400~1500°C; ×8 h, air quenching	1400~1500°C; ×8 h, furnace cooling	Assignments
Raman = 514.5 nm	327		Lattice modes (TTCP)
	390, 408, 448, 481	427, 444	ν 2, bands, symmetric bending vibrations mode
	555, 565, 577, 598, 608, 616	575, 588, 605	ν 4, bands, asymmetric bending vibrations mode
	941, 948, 957, 963	959	ν 1, bands, symmetric stretching mode
	992, 1010, 1027, 1046, 1075, 1095, 1122, 1135	1026, 1040, 1072, 1121	ν 3, bands, asymmetric stretching mode
		3573	OH^− stretching vibration (in HA)
		3619	OH^− stretching vibration (in Ca(OH)2)