Nanoceramics: Synthesis, Characterizations and Applications
135
The coating is reported to accelerate the osseointegration rate and bone mineralization at the bone-implant interface [24]. Silica films were deposited onto titanium by
PECVD and then functionalized with amino groups using 3-aminopropyl triethoxysilane (APTES). The functionalized coating was observed to have greater stability
under physiological conditions and hence can be used as functional biomaterial
coatings [25].
2.4 Mechanochemical Synthesis
Mechanochemical synthesis is a high-energy milling technique which involves the
formation of nanoscale composites. This method involves coupling of chemical
and mechanical phenomena on the molecular scale to produce ceramic nanoparticles. The application of mechanical action through ball mill enables the reaction
to happen at room temperature or temperatures lower than the traditional methods
avoiding external heating. It can be performed in the presence or absence of solvents.
The precursor powders are milled together by placing them in a high-energy mill.
Mechanically induced chemical reactions take place under a controlled atmosphere of
high load and strain conditions. By modifying the reaction conditions nanostructured
compounds having ultrafine grains and homogeneous composition can be produced
[26]. Nanoceramics as small as 5 nm with high crystallinity without agglomeration
can be produced by this method [27]. Precursors are normally a combination of
salt and a metal oxide and they react during milling followed by a heating process.
Nanocomposites of oxide, non-oxide as well as mixed ceramics can be prepared by
this method.
Calcium phosphate can be synthesized by mechanochemical method under both
wet and dry conditions. It was observed that wet grinding slowed down the reaction
rate and increased powder contamination due to erosion and hence it is reported
that dry mechanochemical synthesis is preferred for biomedical applications [28].
By milling AlCl 3 with CaO 5 , nanoparticles of Al 2 O 3 of size 10–20 nm can be
formed [29]. Equal concentrations of lanthanum and silicate substituted apatite was
produced by mechanochemical synthesis. Single-phase products can be produced
by this method and the synthesized apatite was deposited on Ti substrate by microarc oxidation method. The resultant coating exhibited high biocompatibility and no
cytotoxic action on mesenchymal stem cells [30].
Silver nanoparticles were successfully synthesized by combining this method
and green synthesis using egg shell membrane or Origanum vulgare L. plant as the
reducing agent. Silver nitrate was used as the silver precursor. The Ag nanoparticles synthesized by co-milling with Origanum plant exhibited higher antibacterial
activity than the former one [31]. Hydroxyapatite with 20% Ti nanocomposite was
synthesized by combining mechanochemical process with solid-state method. The
resultant nanopowders exhibited high crystallinity, smaller size of about 25 nm and
high purity and have improved bioactivity compared to calcium phosphate nanocomposites [32]. Calcium-deficient hydroxyapatite (CDHA) is used to prepare calcium
135
The coating is reported to accelerate the osseointegration rate and bone mineralization at the bone-implant interface [24]. Silica films were deposited onto titanium by
PECVD and then functionalized with amino groups using 3-aminopropyl triethoxysilane (APTES). The functionalized coating was observed to have greater stability
under physiological conditions and hence can be used as functional biomaterial
coatings [25].
2.4 Mechanochemical Synthesis
Mechanochemical synthesis is a high-energy milling technique which involves the
formation of nanoscale composites. This method involves coupling of chemical
and mechanical phenomena on the molecular scale to produce ceramic nanoparticles. The application of mechanical action through ball mill enables the reaction
to happen at room temperature or temperatures lower than the traditional methods
avoiding external heating. It can be performed in the presence or absence of solvents.
The precursor powders are milled together by placing them in a high-energy mill.
Mechanically induced chemical reactions take place under a controlled atmosphere of
high load and strain conditions. By modifying the reaction conditions nanostructured
compounds having ultrafine grains and homogeneous composition can be produced
[26]. Nanoceramics as small as 5 nm with high crystallinity without agglomeration
can be produced by this method [27]. Precursors are normally a combination of
salt and a metal oxide and they react during milling followed by a heating process.
Nanocomposites of oxide, non-oxide as well as mixed ceramics can be prepared by
this method.
Calcium phosphate can be synthesized by mechanochemical method under both
wet and dry conditions. It was observed that wet grinding slowed down the reaction
rate and increased powder contamination due to erosion and hence it is reported
that dry mechanochemical synthesis is preferred for biomedical applications [28].
By milling AlCl 3 with CaO 5 , nanoparticles of Al 2 O 3 of size 10–20 nm can be
formed [29]. Equal concentrations of lanthanum and silicate substituted apatite was
produced by mechanochemical synthesis. Single-phase products can be produced
by this method and the synthesized apatite was deposited on Ti substrate by microarc oxidation method. The resultant coating exhibited high biocompatibility and no
cytotoxic action on mesenchymal stem cells [30].
Silver nanoparticles were successfully synthesized by combining this method
and green synthesis using egg shell membrane or Origanum vulgare L. plant as the
reducing agent. Silver nitrate was used as the silver precursor. The Ag nanoparticles synthesized by co-milling with Origanum plant exhibited higher antibacterial
activity than the former one [31]. Hydroxyapatite with 20% Ti nanocomposite was
synthesized by combining mechanochemical process with solid-state method. The
resultant nanopowders exhibited high crystallinity, smaller size of about 25 nm and
high purity and have improved bioactivity compared to calcium phosphate nanocomposites [32]. Calcium-deficient hydroxyapatite (CDHA) is used to prepare calcium