Environmentally friendly growth of calcium chlorapatite whiskers from a sodium chloride flux

Katsuya Teshima, Kunio Yubuta, Satoru Ooi, Takaomi Suzuki, Toetsu Shishido, Shuji Oishi

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22 Citations (Scopus)


Environmentally friendly, high-quality, and transparent-colorless calcium chlorapatite (Ca5Cl(PO4)3) whiskers were selectively fabricated by rapid cooling of a sodium chloride flux. The crystal growth was conducted by heating a mixture of solute ((NH4) 2HPO4, CaCl2, and CaCO3) and flux (NaCl) at 1100°C, holding at this temperature for 10 h, and then cooling it at a rate of 5-200°C h-1 to 500°C. The grown crystals were divided into two morphological types, that is, needle and prismatic shapes. The Ca5Cl(PO4)3 whiskers obtained average lengths up to 4.2 mm and widths up to 130 μm. Their form was a hexagonal {1010} cylinder with pyramidal {1011} end faces. The crystal forms and average sizes obviously depended on the cooling rate of the high-temperature solution. The formation ratio of the whiskers was increased with cooling rate, reaching much higher than 80 wt % at 200°C h-1 in all growth runs. It is found that Ca5Cl(PO4)3 whiskers were predominantly grown by controlling the cooling rate. Finally, NaCl was found to be a very suitable flux for an environmentally friendly growth of Ca5Cl(PO 4)3 whiskers.

Original languageEnglish
Pages (from-to)2538-2542
Number of pages5
JournalCrystal Growth and Design
Issue number11
Publication statusPublished - Nov 2006
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics


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