<p>The nucleation and growth kinetics of mullite crystal structure prepared from Algerian natural phosphate (NP) and kaolin materials were studied by differential thermal analysis (DTA) and X-ray diffraction (XRD). The XRD patterns showed that mullite, hydroxyapatite and anorthite were the main crystal structures present in mixtures. From DTA results, several thermal characteristics including the crystallization peak temperature, activation energies, were calculated. The DTA results showed that the characteristics temperature and activation energies were reduced when the NP content was increased at the expense of kaolin material. Bulk crystallization was seen in samples with low/moderate and high NP amounts, respectively, with a fixed (<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10973_2025_14182_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="78" /> </InlineMediaObject> <EquationSource Format="TEX">$n=m=3$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>n</mi> <mo>=</mo> <mi>m</mi> <mo>=</mo> <mn>3</mn> </mrow> </math></EquationSource> </InlineEquation>) and growing (<InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10973_2025_14182_Article_IEq2.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="42" /> </InlineMediaObject> <EquationSource Format="TEX">$n=3$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>n</mi> <mo>=</mo> <mn>3</mn> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10973_2025_14182_Article_IEq3.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="46" /> </InlineMediaObject> <EquationSource Format="TEX">$m=3$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>m</mi> <mo>=</mo> <mn>3</mn> </mrow> </math></EquationSource> </InlineEquation>) number of nuclei. As a result, it is possible to produce the mullite phase using Algerian kaolin raw material and natural phosphate that can be added as a structural modifier of the growth process.</p>

Unveiling the nucleation and growth kinetics of mullite crystals in kaolin and natural phosphate compounds

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发表日期：

2025年4月21日

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Fateh Chouia,
Hocine Belhouchet,
Toufik Sahraoui,
Yousf Islem Bourezg,
Mohamed Hamidouche,
Anne Leriche

摘要

The nucleation and growth kinetics of mullite crystal structure prepared from Algerian natural phosphate (NP) and kaolin materials were studied by differential thermal analysis (DTA) and X-ray diffraction (XRD). The XRD patterns showed that mullite, hydroxyapatite and anorthite were the main crystal structures present in mixtures. From DTA results, several thermal characteristics including the crystallization peak temperature, activation energies, were calculated. The DTA results showed that the characteristics temperature and activation energies were reduced when the NP content was increased at the expense of kaolin material. Bulk crystallization was seen in samples with low/moderate and high NP amounts, respectively, with a fixed ( $n=m=3$ $n = m = 3$ ) and growing ( $n=3$ $n = 3$ and $m=3$ $m = 3$ ) number of nuclei. As a result, it is possible to produce the mullite phase using Algerian kaolin raw material and natural phosphate that can be added as a structural modifier of the growth process.