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. Author manuscript; available in PMC: 2011 Sep 1.
Published in final edited form as: J Am Ceram Soc. 2010 Oct 1;93(10):3116–3123. doi: 10.1111/j.1551-2916.2010.03833.x

Table II.

Experimental Design with Three Factors (Temperature, K2HPO4 Concentration, and pH of the Solution) Varied at Two Levels

Run Temperature (°C) Concentration (M) pH value Surface area (m2/g) Pore size (nm) d/D Reaction time (days)
1 60 0.25 9 145±5 13±2 0.19±0.11 2
2 60 0.02 9 82±5 10±2 0.34±0.03 7
3 37 0.02 12 89±5 12±2 0.55±0.02 7
4 37 0.25 12 123±5 17±2 0.34±0.03 2
5 37 0.02 9 101±5 15±2 0.61±0.03 2
6 37 0.25 9 127±5 19±2 0.36±0.02 2
7 60 0.25 12 140±5 12±2 0.14±0.07 2
8 60 0.02 12 78±5 8±2 0.37±0.09 7
9 37 0.10 9 108±5 17±2 0.54±0.03 2
10 25 0.25 9 101±5 20±2 0.62±0.08 7

The measured properties of the hollow hydroxyapatite microspheres (ratio of hollow core diameter to microsphere diameter [d/D], specific surface area, and average pore size) prepared under each condition for the reaction time used are also shown.