Utjecaj dopanata na kristalizaciju ß- trikalcijevog fosfata

undergraduate thesis

• Title (english): Dopants Influence on the crystallisation of ß-TCP
• Author: Filip Pendić
• Mentor: Vilko Mandić (mentor)
• Committee member: Vilko Mandić (predsjednik povjerenstva)
• Committee member: Krunoslav Žižek (član povjerenstva)
• Committee member: Petar Kassal (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2024-07-08, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

Izrada biokompatibilne keramike na bazi kalcijevih fosfata povoljnih kemijskih i mehaničkih svojstava u današnje vrijeme je još uvijek izazov. Keramika od β-trikalcijevog fosfata pokazuje svojstva koja zadovoljavaju zahtjeve moderne biokeramike. Jedan od načina dobivanja
β-trikalcijevog fosfata je preko njegovog prekursora kalcij deficitnog hidroksiapatita (CDHA), koji se može pripremiti mokrom precipitacijom. Sinteriranjem na temperaturi višoj od 800 °C dolazi do prijelaza u β- trikalcij fosfat. Tokom reakcije mokre precipitacije dodavanjem soli dvovalentnih kationa moguće je dopirati uzorak čime se mijenjaju svojstva krajnjeg produkta. Ispitivani dopanti su bili dvovalentni stroncijev i magnezijev kation čije su se soli dodale nakon reakcije mokre precipitacije i prije sinteriranja dobivenih prahova. Rendgenskom difrakcijom se pokazalo kako su se ispitivanim uzorcima smanjile veličine kristalne rešetke. Infracrvenom spektroskopijom dokazana je čistoća uzorka uz nastanak manje količine pirofosfata zbog lokalne nestehiometrije. Termografskom i diferencijalnom termalnom analizom određena je temperatura prijelaza CDHA u β-TCP za magnezij dopirani uzorak pri ~750 °C, dok se za stroncij dopirani uzorak prijelaz odvija pri ~775 °C. Pretražnom elektronskom mikroskopijom analizirana je morfologija uzoraka. Metodom mokre precipitacije moguće je dopirati β- trikalcijev fosfat te povisiti temperaturu njegovog prijelaza u α-TCP, što je potvrđeno diferencijalnom termalnom analizom pri čemu se magnezij dopiranom uzorku temperatura prijelaza povisila van parametara mjerenja, dok se uzorku dopiranom stroncijem temperatura prijelaza povisila na 1300 °C.

Abstract (english)

Nowadays, manufacturing of calcium phosphate biocompatible ceramics with favorable chemical and mechanical properties is still a challenge. Ceramics made of β- tricalcium phosphate are showing promises within modern bioceramic requirements. One of the possible ways of preparing β- tricalcium phosphate is through its precursor, amorphous calcium hydroxyapatite (CDHA) that can be prepared through wet precipitation method.
A phase transition to β- tricalcium phosphate happens while sintering CDHA at temperature higher than 800 °C. Doping is possible by adding divalent salts while wet precipitation is occurring, which changes the properties of the final product. Analysed dopants were strontium and magnesium divalent cations whose salts had been added after wet precipitation and before sintering of the powder. X-ray diffraction pointed to shrinkage of the unit cell. Infrared spectroscopy with Fourier transformation proved purity of synthesized sample with minor addition of pyrophosphate caused by local non-stoichiometry. Thermogravimetric and differential thermal analysis determined the temperature of phase transition at ~750 °C for magnesium doped sample, while the temperature for strontium doped sample has been determined at ~775 °C. Scanning electron microscopy was used to analyse sample morphology. The differential thermal analysis has proven the possibility to use wet precipitation method to dope β-TCP and raise its phase transition temperature to
α-TCP. The phase transition temperature for magnesium doped sample has been raised to the outside of the measuring parameters while for the strontium doped sample the temperature has been raised to 1300 °C.

• Keywords: biokeramika; bioaktivnost; β- trikalcij fosfat; kalcijevi fosfati; dopiranje
• Keywords (english): bioceramic; bioactivity; β- tricalcium phosphate; calcium phosphates; doping
• Language: croatian
• URN:NBN: urn:nbn:hr:149:222777
• Study programme: Title: Materials Science and Engineering - Undergraduate study; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Embargoed access; Embargo expiration date: 2025-02-01
• Created on: 2024-07-19 10:53:22