Post on 25-Jul-2020
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Istituto di Scienze e Tecnologie Molecolari
ISTM-CNR, Università degli Studi di Padova
e-mail: silvia.gross@unipd.it
Silvia Gross
La chimica moderna e la sua comunicazione
Dipartimento di Scienze Chimiche
Università degli Studi di Padova
e-mail: silvia.gross@unipd.it
http://www.chimica.unipd.it/silvia.gross/
Silvia Gross
Colloid Chemistry
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
1) Sol-gel and nonaqueous sol-gel processes (also MW-assisted)
2) Pechini and citrate method
3) Coprecipitation from an aqueous solution
4) Polyol-assisted synthesis
5) Thermal and photochemical decomposition
6) Hydro- and solvothermal synthesis
7) Nucleation from solutions/ reduction to metal colloids
8) Decomposition of precursors
9) Colloidal methods
10) Micro- and miniemulsion
11) Sonochemical synthesis
12) Templated synthesis
13) Chemical bad deposition
S. Diodati, P. Dolcet, M. Casarin and S. Gross
Pursuing the Crystallization of Mono- and Polymetallic Nanosized Crystalline Inorganic Compounds by Low-Temperature Wet-
Chemistry and Colloidal Routes, Chem. Rev., 2015, 115, 11449–11502
S. Gross, “Sustainable and very low temperature wet-chemistry routes for the synthesis of crystalline inorganic compounds”
Chapter 1 in in “Green Processes in Nanotechnology” V. A. Basiuk and E. V. Basiuk, eds, Springer, 2015.
Wet chemistry/colloidal syntheses
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
1) Hydro- and solvothermal synthesis
strictly speaking, not a colloidal route, but in many cases
involves a suspension as starting system to achieve:
1. Colloidal monodisperse particles
2. Nanoscopic materials which can be post-functionalised
and redispersed
Wet chemistry synthesis routes
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Solvo/hydrothermal synthesis
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Solvo/hydrothermal synthesis
Critical point
The temperature and pressure at which the liquid and vapour
intensive properties (density, heat capacity, etc.) become equal. It is
the highest temperature (critical temperature) and pressure (critical
pressure) at which both a gaseous and a liquid phase of a given
compound can coexist.
IUPAC Goldbook: http://goldbook.iupac.org/C01396.html
hydro/solvothermal synthesis
- supercritical
- subcritical
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Solvo/hydrothermal synthesis
Mari-Ann Einarsrud and Tor Grande, Chem. Soc. Rev., 2014, 43, 2187-2199
A. Rabenau, Angew. Chem., Int. Ed. Engl., 1985, 24, 1026–1040
Definition of hydrothermal reaction
Heterogeneous chemical reaction in aqueous media above room
temperature (normally above 100 °C) and at a pressure greater
than 1 atm
- supercritical
- subcritical
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Solvo/hydrothermal synthesis
Published items in each year (left) and citations in each year (right) on the “hydrothermal synthesis
of nanostructures” (used keywords: “hydrothermal synthesis” and “nanostructures”).
Source Web of Science Dec 2014.
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Why hydrothermal synthesis
Fig. 1 Density, dielectric constant and ionic product, Kw, of pure water at 30 MPa as a function of temperature.
Figure: M.A. Einarsrud , T. Grande
Chem. Soc. Rev., 2014, 43, 2187-2199
ionic product tends to increase with rising
temperature and pressure
viscosity decreases (diffusion enhanced)
dielectric constant of water varies in
dependence to the specific operative
conditions since it increases with higher
pressures, but decreases with rising
temperatures.
Water:
-Solvent
-Pressure-transmitting medium
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Why hydrothermal synthesis?
(closed container)
Temperature/ °C State Density/
kg·m-3
Viscosity/
µPa·s
Dielectric
Constant
Pressure equal to 0.1 MPa
27 Liquid 996.56 853.82 80.20
52 Liquid 987.19 530.32 69.32
77 Liquid 973.73 368.80 61.79
102 Gas 0.590 12.339 1.006
135 Gas 0.543 13.285 1.005
177 Gas 0.484 15.426 1.004
Properties of water and vapor as a function of temperature and pressure [CRC; NIST Database –
http://webbook.nist.gov/cgi/fluid.cgi?ID=C7732185&Action=Page]
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Solvo/hydrothermal synthesis
Feedstock
preparation
Reagents
Growth control agents
Oxides/Hydroxides/salts
Gels /Organics/Acids/Bases
ReactorTemperature (100 to 350oC)
Pressure ( < 15 MPa)
Residence Time (10 min-48 h)
Pressure Let-down
crystalline powderFiltrating/washing/drying
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Solvo/hydrothermal synthesis
AUTOCLAVE
Control on:
- temperature
- pressure
BOMB/HYDROTHERMAL REACTOR
Control on:
- temperature
(pressure is autogenous)
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Solvo/hydrothermal synthesis
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Solvo/hydrothermal synthesis
Byrappa K.; Yoshimura M.; Handbook of Hydrothermal Technology; 2001; Noyes Publications, park Ridge, New Jersey, U.S.A
• Reactants are dissolved (or placed) in water or
another solvent (solvothermal) in a closed
vessel
• Typically alkaline conditions
• Bomb is heated above BP
• Conventional or MW oven
• Commercially:
– Tons of zeolites daily
– Several nanomaterials
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Solvo/hydrothermal synthesis
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Parameters you can play with
Nature of the precursors, solvent
Nominal molar ratios among reagents
Treatment times and temperatures → operating pressure
Filling of the vessel
Peptizing agents, additives, surfactants
Purification steps S. Diodati, PhD Thesis,
Università degli Studi di Padova, 2013
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Solvo/hydrothermal synthesis
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Crystallisation under hydrothermal conditions:
dissolution/precipitation proposed two-step mechanism
1. in situ transformation: the precursor ions are dissolved in the reaction mixture → tiny
quantities of the target compound are able to form (as solutes) in the liquid phase.
2. due to the low solubility, even at high pressure and temperature, of the final compound,
the second phase (diffusion, precipitation and growth) takes place. In this phase,
nucleation centers are formed throughout the system around which crystal growth can
occur.
A. Holden and P. Singer, Crystals and Crystal Growing, Anchor Books Doubleday & Company Inc., Garden
City, New York, 1971.
N. Modeshia, R.I. Walton, Chem. Soc. Rev., 2010, 39, 4303–4325
X. Chen, H. Fan and L. Liu, J. Cryst. Growth, 2005, 284, 434-439.
I. MacLaren and C. B. Ponton, J. Eur. Ceram. Soc., 2000, 20, 1267-1275.
Crystallisation under hydrothermal conds
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Crystallisation under hydrothermal
Hydrothermal dissolution/precipitation: basic mechanism
for the hydrothermal formation of ceramic oxide particles
Dissolution
Precipitation
Modeshia, Walton, Chem. Soc. Rev., 2010, 39, 4303–4325
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Hydrothermal synthesis of nanomaterials
BaTiO3 Nanoparticles
• Ba(OH)2 + TiO2 BaTiO3 nanoparticles
• 300 - 450°C, HT
• Two proposed mechanisms:
– Dissolution-recrystallization
– In situ crystallization
Hakuta, R., Ura, H. Hayashi, H, and Arai, K. Ind.
Eng. Chem. Res. 2005, 44, 840-846
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Hydrothermal synthesis of nanomaterials
hydrothermal crystallization
Hydrothermal crystallisation mechanisms
proposed for barium titanate.
1. the case of heterogeneous nucleation where
BaTiO3 growth occurs on the surface of
undissolved TiO2 particles by reaction with
dissolved barium ions to yield core–shell
type intermediates before the complete
consumption of the remaining solid reagents
2. the case where homogeneous nucleation
occurs, i.e. the dissolution of both Ba and Ti
sources under reaction conditions followed
by the direct formation of BaTiO3 from
solution or at the surface of remaining TiO2
particles
Modeshia, Walton, Chem. Soc. Rev., 2010, 39, 4303–4325
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Hydrothermal synthesis of nanomaterials
BaTiO3 Nanoparticles: in-situ crystallization
Eckert, J.O., Hung-Houston, C.C., Gersten, B.L., Lencka,
M.M., Riman, R.E., J. Am. Ceram. Soc. 1996, 79, 2939.
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Hydrothermal synthesis of nanomaterials
playing with morphologies
Morphologies of BaTiO3 crystallites formed by one-step
hydrothermal reactions.
(a) Dendritic particles.
(b) Plate-like crystallites.
(c) Spherical nanocrystallites.
Modeshia, Walton, Chem. Soc. Rev., 2010, 39, 4303–4325
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Hydrothermal synthesis of nanomaterials
Transformation of titanates into TiO2 NSs
Mao, Y., T.-J. Park, et al. (2007).
"Environmentally Friendly
Methodologies of Nanostructure
Synthesis." Small 3(7): 1122-1139.
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Control on shape and morphology
Different hydroxyapatite crystalline nanostructures obtained through hydrothermal synthesis
depending on parameters.
Sadat-Shojai, M.; Khorasani, M.-T.; Dinpanah-Khoshdargi, E.; Jamshidi, A.
Synthesis methods for nanosized hydroxyapatite with diverse structures
Acta Biomater. 2013, 9, 7591-7621.
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Metal oxide hollow spheres
Hydrothermal synthesis of nanomaterials
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Metal oxide hollow spheres by hydrothermal
templated approach
Hydrothermal synthesis of nanomaterials
Hollow spheres of crystalline metal oxides were
synthesized in a simple one-pot synthesis via a
hydrothermal approach. Various metal salts were
dissolved together with carbohydrates in water,
and the mixtures were heated to 180 °C in an
autoclave. During the hydrothermal treatment,
carbon spheres are formed with metal ions
incorporated into their hydrophilic shell. The
removal of carbon via calcination yields hollow
metal oxide spheres. Using this process, a wide
range of metal oxide hollow spheres was
prepared that are not accessible via sol−gel
chemistry: Fe2O3, NiO, Co3O4, CeO2, MgO, and
CuO hollow spheres that are composed of
nanoparticles. The surface area and thickness of
the shell can be varied or controlled by the
carbohydrate:metal salt concentration.
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Metal oxide hollow spheres by hydrothermal
templated approachSEM image of carbon spheres
obtained from the hydrothermal
treatment of glucose
Hydrothermal synthesis of nanomaterials
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Metal oxide hollow spheres
SEM images of (a) NiO, (b) Co3O4,
(c) CeO2, and (d) MgO hollow
spheres
Hydrothermal synthesis of nanomaterials
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Hydrothermal synthesis of nanostructured
crystalline ferrites and manganites
andSynthesis of nanocrystalline CoFe2O4, MnFe2O4, NiFe2O4, ZnFe2O4,
ZnMn2O4, ZnMnO3, CuMnO2, ZnO, ZnS
combining coprecipitation of oxalates and hydrothermal treatment
• Crystallisation at very low temperature (100-180°C)
• Using water as solvent: greenest solvent!
• Very easy and reproducible procedure
• Very common, cheap and safe precursors
• Effective control over the products stoichiometry
• Compounds obtained in highly crysyalline form
• Small crystallite size (15-40 nm, depending on conditions)
• High yields (60-90%)
• Very pure compounds (clean decomposition of oxalates)
• Magnetic properties assessed
Diodati S.; Pandolfo L.; Caneschi A.; Gialanella S.; Gross S.; Green, very low temperature hydrothermal assisted synthesis
of nanocrystalline transition metal spinel ferrites, Nano Res., 2014, 7, 1027-1042
Minelli, A.; Dolcet,P., Pandolfo, L; Gross S. et al. Pursuing the stabilisation of crystalline nanostructured magnetic
manganites through a green low temperature hydrothermal synthesis, submitted
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Perovskites
MFeO3
• Properties dependant on M metal
• Iron in an oxidation state (III) or (IV)
• Ionic conduction
Applications
• Organic compounds decomposition
• Fuel cells, SOFC
Berenov A.V.; MacManus-Driscoll J.L.; Kilner J.A.; International Journal of Inorganic Materials; 2001; 3,
1109–1111
Yang Y.; Jiang Y.; Wang Y.; Sun Y.; Journal of Molecular Catalysis A: Chemical; 2007; 270, 56–60
Hydrothermal synthesis of nanomaterials
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Spinels
MFe2O4
• Properties vary with M
• Hard/soft magnetic material
• Normal or inverse structure
• Degree of inversion γ
Applications
• Catalysis – Water splitting
• Ferrofluids
• Hyperthermia
• Diagnostic medicine
Carta D.; Casula M. F.; Falqui A.; Loche D.;
Mountjoy G.; Sangregorio C.; Corrias A.; J.
Phys. Chem. C; 2009; 113, 8606–8615
A. Z. Simoes, F. G. Garcia and C. d. S. Riccardi,
Mater. Chem. 90 Phys., 2009, 116, 305-309.
L. Malavasi, C. A. J. Fisher and M. S. Islam,
Chem. Soc. Rev., 2010,
39, 4370-4387.
Hydrothermal synthesis of nanomaterials
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Outline
Coprecipitation of oxalates (high T)
Polycrystalline oxide powders
I.
Fe3+
M2+
H2C2O4
TENOHPrecursor salts
solution
Basification
II.
III.
Metal oxalates
suspension
Purification
IV.
V.
Calcination
Diodati S.; Nodari L.; Natile M.M.; Russo U.; Tondello E.; Lutterotti L; Gross S.; Dalton Trans. 2012; 41, 5517–5525
Coprecipitation of oxalates: an easy and reproducible wet-chemistry synthesis route for transition metal ferrites
S. Diodati, L. Nodari, M. M. Natile, A. Caneschi,, S. Gross et al. European Journal of Inorganic Chemistry (2013) 875-887
Fe3+ + M2+ H2C2O4 + NaOH → Fe2(C2O4) 3↓ + M(C2O4)↓ 600-900°C
Hydrothermal synthesis of nanomaterials
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Hydrothermal synthesis: very low T!
Nanosized crystalline oxides
I. II. III.
Metal oxalates
suspension
Hydrothermal
treatmentCentrifugation
Byrappa K.; Yoshimura M.; Handbook of Hydrothermal Technology; 2001; Noyes Publications, park Ridge, New Jersey, U.S.A
70-120 °C
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Hydrothermal synthesis: crystallinity
XRPD patterns and XPS spectra of a) CoFe2O4; b) MnFe2O4; c) NiFe2O4 d) ZnFe2O4
Cou
nts
/a.u
.
8070605040302010
Bragg Angle/°
b
a(111)(220)
(311)
(400)(422)
(511) (440)
(111)(220) (400)
(422)
(440)(511)
(311)
(311)
(440)(511)(400)
(311)
(220)(111)
c
(111) (220)(400) (511)
(440)
d
Co
un
ts/a
.u.
1200 1000 800 600 400 200 0
B.E./eV
C1s
O1sFe2pMn2p
Fe LMM
Mn LMM
O KLL
Na1s
Fe3p
C KVV
C KVV
O KLL
Fe LMM
Ni LMM
Fe2p
Ni2p
C1s
O1s
Fe3p
c
Fe3pC1s
O1s
Na1sFe2pCo2p
Fe LMMCo LMM
b
a
Fe3p
d
C1s
O1sFe2pFe LMM
O KLL
Zn2pC KVV
Zn LMM
e
Zn2p
O KLL
C KVV
Fe LMM Fe2pO1s
Zn LMM C1s Fe3p
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Hydrothermal synthesis: TEM
TEM micrographs of a) CoFe2O4; b) MnFe2O4; c) NiFe2O4 d) ZnFe2O4
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Coprecipitation
500 nm
CoFe2O4
Method Fe/Co
(Theoretical)
Fe/Co (XPS) Fe/Co
(ICP-AES)
Sol-gel 2.0 2.1 2.0
Coprecipitation 2.0 2.1 2.0
Hydrothermal 2.0 2.0 1.9
Hydrothermal
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
MnFe2O4
Pure phase through
hydrothermal and
nonaqueous sol-gel
Rapid synthesis
Crystallite sizes in the 10 -
40 nm range
Co
un
ts/a
.u.
8070605040302010Bragg Angle/2
(111)
(220)
(311)
(400)(511)
(440)
(422) (533) (a)
(b)
(c)
Optimisation of the hydrothermal synthesis for shorter times
Diodati S.; Pandolfo L.; Caneschi A.; Gialanella S.; Gross S.; Green, very low temperature hydrothermal assisted
synthesis of nanocrystalline transition metal spinel ferrites; Nano Research, 2014
Nonaqueous sol-gel
Hydrothermal
Hydrothermal
MnFe2O4: comparison
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
role of the pressure: hydro vs reflux
possible to reproduce the syntheses under reflux conditions (i.e. in an open system):
crystallinity
BUT:
- lower purity
- lower yields
This can be likely attributed to the pressure involved (which is possibly further enhanced
during hydrothermal synthesis by decomposition of the oxalate precursors to CO2).
Diodati S.; Pandolfo L.; Caneschi A.; Gialanella S.; Gross S.; Green, very low temperature hydrothermal assisted
synthesis of nanocrystalline transition metal spinel ferrites; Nano Research, 2014
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Following crystallisation (time-resolved)
X-ray powder diffraction patterns of CoFe2O4, MnFe2O4, NiFe2O4 and ZnFe2O4 nanoparticles. Straight lines represent the corresponding MFe2O4 pattern
Dolcet, Smarsly, Mascotto, Gross et al. Green Chem, 2018, 20, 2257
Cyrstalline materials already after 1 hour→ strong energy consumption reduction
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Following crystallisation (time-resolved)
X-ray powder diffraction patterns of CoFe2O4, MnFe2O4, NiFe2O4 and ZnFe2O4 nanoparticles. Straight lines represent the corresponding MFe2O4 pattern
Dolcet, Smarsly, Mascotto, Gross et al. Green Chem, 2018, 20, 2257
Not relevant changes in crystallite size upon treatment
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Representative TEM images of ZnFe2O4 particles after 1h
(A,B), 9h (D,E), 18h (G,H) and 24h (J,K) and the respective
SAED patterns for 1h (C), 9h (F), 18h (I) and 24h (L).
Main outputs:
particle shape and size remain almost constant
throughout the different synthesis times
particles exhibit diameters in the range of 5-8 nm:
nearly independent of the synthesis time.
single-crystalline particles are present
high crystallinity is achieved even after only one hour
of synthesis time at very low temperature (135°C)
Following crystallisation time-resolved
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Synthetic approach: hydrothermal (180°C)
Water based
Good yield and purity
Fast, reproducible
Low cost
Low temperature
Good control on experimental parameters Precursors
Molar ratios
Time and temperature
(t: 1, 3, 6, 9,12, 24, 48 h; T: 150 – 180 °C)
Coprecipitation of
oxalates
Hydrothermal
synthesis
Crystalline
nanostructured
oxides
Pursuing the stabilization of crystalline nanostructured magnetic manganites through a green low
temperature hydrothermal synthesis
A. Minelli, P. Dolcet., S. Diodati, L. Pandolfo, A. Caneschi, S. Gross et al. submitted
Unraveling the very fast copper manganite crystallisation at very low temperature: a combined
spectroscopic and diffractometric approach
P. Dolcet, A. Minelli, F. Zorzi, P. Vöpel, H. Amenitsch, B. Smarsly, F. Nestola, B. Sartori, and S. Gross, in
preparation
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Synthetic approach: hydrothermal (180°C)
ZnNO3 + Mn(OAc)2 + 2 H2C2O4 ZnMn2O4
Cu(NO3)2 + Mn(OAc)2 + 2 H2C2O4 CuMnO2
ZnCl2 + MnCl2 + 2 H2C2O4 ZnMnO3
1.Metal oxalates precipitation 3. Nanostructured oxides
2. Hydrothermal
conditions
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
ZnS Hydrothermal
Vessel sealed and treated at
135 °C ( P = 476 kPa)
Na2S 0.2 M + Zn(acetate)2 0.1 M
Variation of density, viscosity, dielectric
constant, and ionic product of water
+ redissolution reactions
Different crystallization pathways
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
ZnS Hydrothermal
Pure sphalerite-phase ZnS NPs
21 nm (TEM & size-strain analysis)
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
ZnS Hydrothermal
Thermodynamic equilibrium shape
(Wulff construction)
Rhombic dodecahedron
Only (110) face
Rhombic dodecahedron
projections found in the
TEM images
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Hydrothermal synthesis of nanostructured
crystalline ferrites, manganites, sulfides
andSynthesis of nanocrystalline CoFe2O4, MnFe2O4, NiFe2O4, ZnFe2O4, MgFe2O4,
quaternary ferrites ZnxCo1-xFe2O4, ZnMn2O4, ZnMnO3, CuMnO2, ZnO, ZnS,
CuS, Ag2S, PbS (not yet FexSy…)
• At very low temperature (100-150°C) within very short processing time
• Using water as solvent: greenest solvent
• Very easy and reproducible procedure
• Earth abundant, cheap and safe precursors
• Effective control over the products stoichiometry
• Compounds obtained in highly crystalline form
• Small crystallite size (5-40 nm, depending on conditions)
• High yields (70-90%)
• Very pure compounds (clean decomposition of oxalates)
Diodati S.; Pandolfo L.; Caneschi A.; Gialanella S.; Gross S.; Green, very low temperature hydrothermal
assisted synthesis of nanocrystalline transition metal spinel ferrites, Nano Res., 2014, 7, 1027-1042
Minelli, A., Dolcet, P., L. Pandolfo, Gross S. et al. Pursuing the stabilisation of crystalline nanostructured
magnetic manganites through a green low temperature hydrothermal synthesis, J. Mater. Chem. C, 2017, 5,
3359-3371
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Hydrothermal synthesis of nanomaterials
Pros & contra
• Pros:
– New materials
– Same materials in milder conditions
– Explores unconventional crystallisation paths
– Easy, relatively cheap
– Water based
– Mild conditions of synthesis
Silvia Gross – Chimica dei Colloidi – Laurea Triennale in Chimica
Hydrothermal synthesis of nanomaterials
Pros & contra
• Contra:
– Difficult to control morphology, size
– Not for all materials
– May obtain variation in size
– Black box (but….)