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==Kalcij deficijentni hidroksapatit==
:9.6Ca(NO<sub>3</sub>)<sub>2</sub>[[Kalcij]] + 6deficijentni ( NH<sub>4</sub>ne-stohiometrijski) 2HPO<sub>4</sub> →hidroksiapatit, Ca<sub> 9.610-x</sub> (PO<sub>4</sub>)<sub> 5.6 -x</sub> (HPO<sub>4</sub>)<sub> 0.4x</sub> (OH)<sub> 1.62-x</sub> , gdje je: ▼[[Kalcij]] deficijentni (ne-stohiometrijski) hidroksiapatit, Ca<sub>10-x</sub>(PO<sub>4</sub>)<sub>6-x</sub>(HPO<sub>4</sub>)<sub>x</sub>(OH)<sub>2-x</sub> (where x is between 0 and 1) has a Ca/P ratio between 1.67 and 1.5. The Ca/P ratio is often used in the discussion of calcium phosphate phases.<ref name="Bioactive">{{cite book |last1=Rey, C. |first1= |last2=Combes, C. |first2= |last3=Drouet, C.|first3= |last4=Grossin, D.|first4= |year= 2011 |chapter= 1.111 - Bioactive Ceramics: Physical Chemistry|chapterurl=http://www.sciencedirect.com/science/article/pii/B9780080552941000234 |editor1-last=Ducheyne |editor1-first=Paul |editor2-last= |editor2-first= |title=Comprehensive Biomaterials |url= |volume=1 |issue= |edition= |location= |publisher=Elsevier |publication-date=2011|pages=187–281 |bibcode= |doi=10.1016/B978-0-08-055294-1.00178-1 |isbn=978-0-08-055294-1 |issn= |jstor= |access-date= }} {{Subscription or libraries|sentence|via=[[ScienceDirect]]}}</ref> Stoichiometric apatite Ca<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>(OH)<sub>2</sub> has a Ca/P ratio of 10:6 normally expressed as 1.67. The non-stoichiometric phases have the hydroxyapatite structure with cation vacancies (Ca<sup>2+</sup>) and anion (OH<sup>–</sup>) vacancies. The sites occupied solely by phosphate anions in stochiometric hydroxyapatite, are occupied by phosphate or hydrogen phosphate, HPO<sub>4</sub><sup>2–</sup>, anions.<ref name="Bioactive" />
'''x''' = (između 0 i 1) ima Ca/P odnos 1,67 - 1,5.<br> Ca/P odos se često upotrebljava u raspravamao [[kalcij]] [[fosfat]]nih faza.
Preparation of these calcium deficient phases can be prepared by precipitation from a mixture of [[calcium nitrate]] and [[diammonium phosphate]] with the desired Ca/P ratio, for example to make a sample with a Ca/P ratio of 1.6:<ref name = ChampionI> {{cite journal |title=Calcium phosphate apatites with variable Ca/P atomic ratio I. Synthesis, characterisation and thermal stability of powders |authors=Raynaud, S., Champion, E., Bernache-Assollant, D., Thomas, P. |doi=10.1016/S0142-9612(01)00218-6 |url=http://www.sciencedirect.com/science/article/pii/S0142961201002186|date= February 2002|volume= 23|issue= 4 |year= |pages=1065–1072 |issn=0142-9612 |journal =Biomaterials }} {{Subscription or libraries|sentence|via=[[ScienceDirect]]}}</ref>
Stoihiometrijski [[apatit]] Ca<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>(OH)<sub>2</sub> ima Ca/P odnos 10:6, uz normalno ispoljavanje 1.67. Nestoihiometrijske faze imaju hidroksiapatitnu strukturu sa (Ca<sup>2+</sup>) i anion (OH<sup>–</sup>) slobodna mjesta. Mjesta tako zauzimaju fosfatni anioni u stohiometrijskom hidroksiapatitu, zauzima [[fosfat]] ili [[vodik]] fosfat u HPO<sub>4</sub><sup>2–</sup>, anion.
▲:9.6Ca(NO<sub>3</sub>)<sub>2</sub> + 6(NH<sub>4</sub>)2HPO<sub>4</sub> → Ca<sub>9.6</sub> (PO<sub>4</sub>)<sub>5.6</sub> (HPO<sub>4</sub>)<sub>0.4</sub> (OH)<sub>1.6</sub>
Preparacija ove kalcijske deficijentne faze može se prirediti precipitacijom iz a mješavine [[kalcij nitrat]]a i [[diamonijum fosfat]]a sa željenim Ca/P odnosom, npr. za dobijanje uzorka sa Ca/P odnosom 1,6.<ref>[http://www.sciencedirect.com/science/article/pii/S0142961201002186,,Biomaterials.</ref>
:9.6Ca(NO<sub>3</sub>)<sub>2</sub> + 6(NH<sub>4</sub>)2HPO<sub>4</sub> → Ca<sub>9.6</sub> (PO<sub>4</sub>)<sub>5.6</sub> (HPO<sub>4</sub>)<sub>0.4</sub> (OH)<sub>1.6</sub>
Sintering these non-stoichiometric phases forms a solid phase which is an intimate mixture of tricalcium phosphate and hydroxyapatite, termed [[tricalcium phosphate|biphasic calcium phosphate]]:<ref name="ValletRegi1997">{{cite journal |title= Synthesis and characterisation of calcium deficient apatite|authors=Vallet-Regí, M.;Rodríguez-Lorenzo, L.M. |doi=10.1016/S0167-2738(97)00213-0 |url=http://www.sciencedirect.com/science/article/pii/S0167273897002130|date= November 1997 |volume=101–103, Part 2 |issue= |pages=1279–1285| journal =Solid State Ionics}} {{Subscription or libraries|sentence|via=[[ScienceDirect]]}}</ref>
Sintiziranje ove nestehiometrijske faze formira čvrstu fazu koja je intimna mješavina trikalcijum fosfata i hidroksiapatita, zvanu bifazni kalcijum fosfat
:Ca<sub>10-x</sub>(PO<sub>4</sub>)<sub>6-x</sub>(HPO<sub>4</sub>)<sub>x</sub>(OH)<sub>2-x</sub> → (1-x)Ca<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>(OH)<sub>2</sub> + 3xCa<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>
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