title: Thermal decomposition of Lingula shell apatite.
abstract: Lingula shell is composed of apatite with a preferred orientation. The shell apatites of Lingula unguis(Lu) and Lingula shantoungensis(Ls) were characterized and compared with apatite of human tooth enamel. Insight into the Lingula apatite was studied by following the change of lattice parameter, transformation to beta-tricalcium phosphate (beta-TCP), and the loss and change of CO3, OH, and H2O after heating up to 1,000 degrees C in air and N2 for 24 hours. The OH stretching band was not observed in unheated apatites and in apatites heated in dried N2. Lu and Ls apatite produced 26 and 17 wt% of beta-TCP at 700 degrees C, respectively. Fifty to 60% of H2O was lost at 200 degrees C, being accompanied by a drastic contraction of the a- and c-axis and a drastic decrease in the crystallinity. These results indicate that (1) Lu and Ls shell apatite is CO3 containing F + Cl-apatite, and (2) the structural H2O of the Lingula apatite is loosely bounded such that they are lost at lower temperature than tooth enamel.
authors.affiliation: Asahi University School of Denistry, Dental Materials and Technology, Gifu, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Iijima
authors.forename: H
authors.initials: H
authors.lastname: Kamemizu
authors.forename: N
authors.initials: N
authors.lastname: Wakamatsu
authors.forename: T
authors.initials: T
authors.lastname: Goto
authors.forename: Y
authors.initials: Y
authors.lastname: Moriwaki
mesh_terms: D000818:Animals; D002130:Calcium Phosphates / Q000032:analysis; D002648:Child; D003461:Crystallography; D003743:Dental Enamel / Q000737:chemistry; D017886:Durapatite; D006358:Hot Temperature; D006801:Humans; D006882:Hydroxyapatites / Q000032:analysis*; D008974:Mollusca / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
chemical_list: D002130:Calcium Phosphates; D006882:Hydroxyapatites; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; D017886:Durapatite; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous