Apatite family

The apatite family of minerals is a common feature to many of the minerals shown in Table 3. In nature, the apatite mineral structure conforms to the 6/m class of minerals with hexagonal crystal structure and the generic formula Me5(X04)3Z where Me is Ca, Sr, Ba, Cd, and Pb (typically), X = P, As, V, Mn, and Cr and Z = OH, F, Cl, and Br. In addition to caibon-ate apatite, chloroapatite, chloropyromorphite, fluoroaptite, fluoropyromorphite, hydroxyapatite, and hydroxypyromorphite, the family includes abukumalite ((Ca,Th,Ce)5(P04, Si04)3(0H,F)),... 

Solid solutions within the apatite family are readily synthesized in the laboratory. Some examples include (Ca,Zn,Pb)5(P04)30H (Panda et al. 1991), (Ca,Cd,Pb)5(P04)30H (Mahapatra et al. 1995), (Ca,Sr,Cu)5(P04)30H (Pujari Patel 1989), or other apatite solid solutions containing various quantities of Cd, Mg, Zn, Cd or Y (Ergun etal. 2001). They are also found naturally (Botto etal. 1997). Unlike well-ordered naturally occurring minerals, these solid solutions may actually be the more typical form of the mineral in stabilized ash systems given the system complexity, rapid precipitation kinetics, and wide prevalence of available divalent cations. 

A typical suite of X-ray diffractograms is shown in Fig. 8 for bottom ash samples. Diffraction peaks differ between sample treatments. With bottom ash, a large amorphous background signal is present. Thirty to 40 peaks are selected for analysis in the search match software. As shown in Tables 6 to 8, a number of metal phosphates were found in the treated samples and the treated and leached samples for the bottom ash, scrubber residue, and vitrification dust samples. Apatite family and tertiary metal phosphates are common to both the treated and unleached samples and the treated and leached samples for all three ashes. 

Fluorapatite is by far the most common member of apatite family found in igneous rocks. However, most natural fluorapatite contains some chlorine and hydroxyl as well, and these constituents can attain high concentrations in some cases. The other halogens, bromine and iodine, also occur in apatite, but their concentrations are much lower than chlorine and fluorine. Many cations commonly substitute for calcium and phosphorus in apatite, however, they rarely reach concentrations that warrant the definition of a separate mineral species. 

The X-ray diffraction pattern shown below was obtained for a compound believed to be the bromide analog of pyromorphite, a member of the apatite family. The XRD line pattern serves as a fingerprint of the compound. The two... 

The mineral part of bone and teeth is made of a crystalline form of calcium phosphate similar to hydroxyapatite [Caio(P04)s(OH)2]. The apatite family of mineral [Aio(B04)eX2] crystallizes into... 

The apatite family of minerals has the general formula Aio(B04)eX2. In HA, or more specifically calcium hydroxyapatite, A = Ca, B = P, and X = OH. The mineral part of teeth and bones is made of an apatite of calcium and phosphorus similar to HA crystals. Natural bone is -70% HA by weight and 50% HA by volume. 

Na2M(P04)F (M = Sr, Ca) belongs to another typical non-apatite family halo-phosphate phosphor host [63, 64]. The novel green-emitting phosphor Na2CaP04F Eu was synthesized, which has broad excitation bands between 250 and 450 nm with the green emission centered at 506 nm. The optimum concentration of Eu " in Na2CaP04F Eu is determined to be 0.02 mol. Moreover, Dy " ... 

Pure fluorapatite, usually considered as the prototype of the apatite family (e.g. Nathan, 1984), belongs to hexagonal syngony. The F-apatite lattice can be described by a unit cell, having a shape of a prism with rhomboidal base. This unit cell can be characterised by two lattice parameters, a (margin of the base) and c (height). In the case of F-apatite, approximate values are a = 9.37 A and c = 6.8SA (McConnell, 1973). Pure F-apatite can be obtained synthetically, but it occurs seldom in nature, and is not known to be formed biogenically (Carter, 1990). 

Phosphorus occurs in various phosphate minerals, the most important belonging to the apatite family, which originate from the compressed remains of ancient organisms. Apatite has the general formula Ca5(P04)3X, where X can be OH" (hydroxyapatite), F (fluorapatite) or Cl" (chlorapatite). 

Phosphorus is the eleventh element in order of abundance in crustal rocks of the earth and it occurs there to the extent of 1120 ppm (cf. H 1520 ppm, Mn 1060 ppm). All its known terrestrial minerals are orthophosphates though the reduced phosphide mineral schrieber-site (Fe,Ni)3P occurs in most iron meteorites. Some 200 crystalline phosphate minerals have been described, but by far the major amount of P occurs in a single mineral family, the apatites, and these are the only ones of industrial importance, the others being rare curiosities. Apatites (p. 523) have the idealized general formula 3Ca3(P04)2.CaX2, that is Caio(P04)6X2, and common members are fluorapatite Ca5(P04)3p, chloroapatite Ca5(P04)3Cl, and hydroxyapatite Ca5(P04)3(0H). In addition, there are vast deposits of amorphous phosphate rock, phosphorite, which approximates in composition to fluoroapatite. " These deposits are widely... 

This section provides an overview of the most important families of compounds which display high values of ionic conductivity. Inevitably, limitations of space mean that a number of interesting systems are not discussed, including several systems which are the subject of current research activity (e.g., the LAM OX compounds [7] and apatite-structured oxides [8]) which do not conveniently fit into one ofthe major groups discussed below. 

The canasite glass-ceramic family was extended (Wolcott 1994) by the controlled co-precipitation of two phases from an appropriate base glass. In this process, a canasite-apatite glass-ceramic was developed with the composition 42-70 wt% Si02> 6—12 wt% Na20, 3—10 wt% K2O, 20—30 wt% CaO, 3-11 wt% F, and 2-13 wt% P2O5, with additions of Al.,0, and... 

Hydroxyapatite (HA) is the primary mineral content of bone representing 43 % by weight. HA is a calcium phosphate whose stoichiometric formula corresponds to a Caio(P04)6(OH)2, with a Ca/P molar ratio = 1.67. HA belong the mineral family of Apatites whose name derived from Greek aTraxa means deception or deceit, due to the facility it was confused with other mineral species like the beiyl or the tourmaline [50]. 

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