The Hydrothermal Synthesis Duration Influence on Calcium Phosphate and Hydroxyapatite Phase Composition

This paper reports the hydrothermal synthesis process duration influence on phase composition, crystallinity degree, morphology and dispersity of the hydroxyapatite powder. The calcium phosphate and hydroxyapatite were synthesized in precursor system Ca(NO[3])[2](NH[4])[2]HPO[4]-NH[4]OH. The obtained powders were characterized with X-Ray diffraction, Fourier Transform spectroscopy (FTIR) and Raman spectroscopy. The results demonstrate: the increasing of the synthesis time duration has no influence on the phase composition. However, the synthesis duration time growth from 12 to 48 hours make possible increase the crystallinity degree from 0.68 to 0.98

The pH Level Influence on Hydroxyapatite Phase Composition Synthesized with Hydrothermal Method

This paper reports the pH level influence on hydroxyapatite phase composition synthesized with hydrothermal method in Ca(OH)2-H3PO4, Ca(NO3)2-(NH4)2HPO4-NH[4]OH, Ca(OH)[2]-NH[4]H[2]PO[4].The obtained samples were studied with X-Ray diffraction, Fourier Transform Infrared (FTIR) and Raman spectroscopy. The one phase Ca[5]H[2]O[13]P[3] high crystallinity hydroxyapatite was synthesized with hydrothermal method at pH equal to 11. The crystallinity degree was calculated from the X-Ray diffraction pattern and became 0.96. The increasing pH level from 7 to 11 provides obtaining one phase hydroxyapatite at pH level 11 instead the two phase Ca[9.04](PO[4])6(OH)[1.68], CaHPO[4] at pH level 9 and CaPO[3](OH), Ca(OH)[2] at pH level 7

The Hydrothermal Synthesis Duration Influence on Calcium Phosphate and Hydroxyapatite Phase Composition

This paper reports the hydrothermal synthesis process duration influence on phase composition, crystallinity degree, morphology and dispersity of the hydroxyapatite powder. The calcium phosphate and hydroxyapatite were synthesized in precursor system Ca(NO[3])[2](NH[4])[2]HPO[4]-NH[4]OH. The obtained powders were characterized with X-Ray diffraction, Fourier Transform spectroscopy (FTIR) and Raman spectroscopy. The results demonstrate: the increasing of the synthesis time duration has no influence on the phase composition. However, the synthesis duration time growth from 12 to 48 hours make possible increase the crystallinity degree from 0.68 to 0.98

The pH Level Influence on Hydroxyapatite Phase Composition Synthesized with Hydrothermal Method

This paper reports the pH level influence on hydroxyapatite phase composition synthesized with hydrothermal method in Ca(OH)2-H3PO4, Ca(NO3)2-(NH4)2HPO4-NH[4]OH, Ca(OH)[2]-NH[4]H[2]PO[4].The obtained samples were studied with X-Ray diffraction, Fourier Transform Infrared (FTIR) and Raman spectroscopy. The one phase Ca[5]H[2]O[13]P[3] high crystallinity hydroxyapatite was synthesized with hydrothermal method at pH equal to 11. The crystallinity degree was calculated from the X-Ray diffraction pattern and became 0.96. The increasing pH level from 7 to 11 provides obtaining one phase hydroxyapatite at pH level 11 instead the two phase Ca[9.04](PO[4])6(OH)[1.68], CaHPO[4] at pH level 9 and CaPO[3](OH), Ca(OH)[2] at pH level 7

Microwave treatment and pH influence on hydroxyapatite morphology and structure

This paper reports the influence of microwave treatment duration and pH conditions of initial precursors on the morphological and crystalline dispersity of the hydroxyapatite (HAp) synthesized by hydrothermal method.The obtained HAp samples were studied by scanning electron microscopy, X-Ray diffraction method and low nitrogen adsorption method. We have obtained nanostructured crystalline hydroxyapatite with 95% crystallinity, porous structure and average particles size in interval 17...46 nm consolidated in aggregates with size distribution of 0.5...25 [mu]m. The pH growth from 8 to 13 results in double increase of HAp specific area(from 69 up to 133 m{2}/g), meanwhile microwave irradiation brings to particles aggregation: HAp treated during 0... 10...30 min have specific surface are 112...67...41 m{2}/g, respectively. As a result at pH=13 and without microwave irradiation treatment we synthesized HAp with maximum surface compared to the surface of natural HAp that makes obtained HApto be promising material in biotechnological applications

NANOSTRUCTURES (Cu,Zn)/h-BN FOR HETEROGENEOUS CATALYSIS

(Cu,Zn)/h-BN heterogeneous nanostructures were successfully synthesized by wet chem-istry reaction. Metal nanopartciles, 10-20 nm in dimension, were homogeneously distributed over the BN support. Nanocatalysts showed high catalytic activity in CO oxidation reaction.Работа выполнена при финансовой поддержке Российского Научного Фонда (соглашение № 20-79-10286)

Композиты Alnano/h–Bnnano, изготовленные методом шарового размола и искрового плазменного спекания

В работе изучено получение высокопрочных композитов на основе Al/h–BN, изготовленных путем сочетания шарового размола и искрового плазменного спекания с использованием порошков Alnano и h–BNnano.Al/h–BN composites with high strength were fabricated by a combination of ball milling and spark plasma sintering using nano Al and nano BN powders.Работа выполнена при финансовой поддержке CzechNanoLab, MEYS CR (LM2018110) и проекта OPVVV «Новые нанострук туры для инженерных приложений» № CZ.02.1.01/0.0/0.0/16_026/0008396.The work was carried out with the financial support of CzechNanoLab, MEYS CR (LM2018110) and the OPVVV project “New nanostructures for engi neering applications” No. CZ.02.1.01/0.0/0.0/16_026/0008396

PT/H-BN NANOSTRUCTURES DEVELOPMENT FOR HETEROGENEOUS CATALYSIS

Pt/h-BN hybrid nanostructures were successfully synthesized by the impregnation method. Pt nanopartciles, 3-10 nm in size, were homogeneously distributed on over the BN support. Nanocatalysts showed high catalytic activity in CO oxidation, full conversion was achieved at 184 °С.Работа выполнена при финансовой поддержке Российского научного фонда (проект № 20-79-10286)

Study of Chemical and Morphological Transformations during Ni2Mo3N Synthesis via an Oxide Precursor Nitration Route

Chemical and morphological transformations during Ni2Mo3N synthesis were studied in this work. Nitride samples were synthesized from oxide precursors in H2/N2 flow and were analyzed by thermogravimetry, X-ray diffraction analysis, scanning electron microscopy, and energy dispersive X-ray spectroscopy methods. In addition, physical and chemical adsorption properties were studied using low-temperature N2 physisorption and NH3 temperature-programmed desorption. It was shown that nitride formation proceeds through a sequence of phase transformations: NiMoO4 + MoO3 → Ni + NiMo + MoO2 → Ni + NiMo + Mo2N → Ni2Mo3N. The weight changes that were calculated from the proposed reactions were in agreement with the experimental data from thermogravimetry. The morphology of the powder changed from platelets and spheres for the oxide sample, to aggregates of needle-like particles for the intermediate product, to porous particles with an extended surface area for the nitride final product. The obtained results should prove useful for subsequent Ni2Mo3N based catalysts production process optimization