The Impact of the Chemical Synthesis on the Magnetic
Properties of Intermetallic PdFe Nanoparticles.
I. Castellanos-Rubio1, M. Insausti1,2, I. Gil de Muro1, D. Carolina Arias-Duque3, Juan
Carlos Hernández-Garrido3, T. Rojo1,4, L. Lezama* 1,2
1
Dpto. de Química Inorgánica, Universidad del País Vasco, UPV/EHU, P.O. Box. 644,
E-48080, Bilbao, Spain
2
3
BC Materials, Parque Científico y Tecnológico de Bizkaia, E-48160, Derio, Spain
Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química
Inorgánica, Facultad de Ciencias, Universidad de Cadiz, Apartado 40, Puerto Real,
Cadiz 11510, Spain
4
CIC energiGUNE, Parque Tecnológico de Álava, Albert Einstein 48, ED. CIC, 01510,
Miñano, Spain
* Corresponding autor: Luis Lezama – luis.lezama@ehu.es
SUPPORTING INFORMATION
Table of contents
Table S1. Some physicochemical properties of the complete set of PdFe samples: Pd:Fe
molar ratio of the final product, organic matter percent (O.M. %), inorganic diameter(D)
and standard deviation (σ) from TEM; and the corresponding synthetic conditions:
reactives, amounts, solvent and the temperature in the last stage of the synthesis (T3).
Figure S1. Deconvolution of (111) diffraction peak for samples A-F.
Table S2. Parameters obtained from deconvolution of (111) diffraction peak and
calculated particle size using Scherrer equation.
Figure S2. FTIR spectra of pure dodecanetiol, oleylamine, oleic acid and PdFe
nanoparticles coated with ligands (sample C and F ).
Model S1. Effective anisotropy constant, Keff, calculation within the Non-Interacting
Super-Paramagnetic (SPM) model.
Table S1. Some physicochemical properties of the complete set of PdFe samples: Pd:Fe
molar ratio of the final product, organic matter percent (O.M. %), inorganic diameter(D)
and standard deviation (σ) from TEM; and the corresponding synthetic conditions: reactives,
amounts, solvent and the temperature in the last stage of the synthesis (T3). The reducer has
been 1,2 hexadecanodiol. And the Pd precursor has been Pd(C5H7O2)2 (0.5 mmol) almost in
all the cases*.
Sample Pd:Fe O.M
%
A-2
B-2
C-1
C-2
C-3
C-4
C-5
C-6
C-7
C-8
D-1
D-2
H-1
H-2
H-3
H-4
H-5
H-6
H-7
H-8
H-9
K-1
K-2
K-3
K-4
K-5
K-6
K-7
M-1
3.4:1
1.2:1
3.2:1
12.5:1
16.5:1
5:1
4.5:1
3.3:1
3.5:1
4.6:1
4.7:1
11.4:1
2.9:1
3.5:1
4.8:1
3.3:1
3.5:1
2:1
3.8:1
3:1
1.4:1
3:1
1:1
3.1:1
4:1
6.4:1
3.5:1
1.6:1
8:1
D (σ)
/nm
48.4 7.4±2.2
24.4 10.5±3.0
50.3 6.0±1.4
21.0 --------35.3 --------38.1 5.2±0.7
60.0 3.7±0.5
43.0 5.2±1.1
64.0
3-7
30.9
5-10
24.4 2.7±0.5
22.3 2.9±0.5
29.0 7.8±2.1
15.7 4.2±0.7
38.6 4.3±0.8
32.3 --------17.0 4.3±0.7
24.0 4.9±1.0
11.2
4-7
64.8 7.4±1.6
56.1 8.3±1.6
21.2 --------34.0 --------14.5 13±3.1
10.0 7.5±0.9
15.0
5-8
23.7 4.2±0.5
30.2 4.6±0.5
16 11.1±1.2
Fe(CO)5 Reduc. R-NH2
R-SH
/mmol /mmol Cn/mmol Cn/mmol
0.75
1.5
0.75
0.75
0.75
0.75
0.75
0.75
0.75
0.75
0.75
0.75
0.75
0.75
0.75
0.75
0.75
0.75
0.75
0.75
1.5
0.75
1.125
0.75
0.75
0.75
0.375
0.75
0.75
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
3
3
5
5
20
10
10
10
C16/0.5
C16/0.5
C16/0.5
C16/0.5
C16/0.5
C16/0.5
C16/0.5
C16/0.5
C16/0.5
C16/0.5
C8/0.5
C6/0.5
C16/6
C8/6
--------C8/6
--------C12/6
--------C16/6
C8/6
C16/0.5
C16/0.5
C16/6
C16/6
C16/6
C16/20
C16/20
C16/20
----------------------------------------------------------------------------------------------------------------C6/0.5
--------C6/0.5
--------C12/0.5
--------------------------------------------------------C12/1
C12/1
C12/1
R-COOH
Cn/mmol
**Solvent
/T3(ºC)
C16/0.5
C16/0.5
C16/0.5
C16/0.5
C16/0.5
C16/0.5
C16/0.5
C16/0.5
C16/0.5
C16/0.5
----------------C16/0.5
C8/0.5
C8/0.5
----------------C8/0.5
C8/0.5
C16/1
C8/1
C16/0.5
C16/0.5
C16/1
C16/1
C16/1
C16/1
C16/1
C16/1
b/289
b/289
b/120
b/120
b/120
b/120
b/120
b/120
b/120
b/120
b/120
b/120
t/110
t/110
t/110
t/110
t/110
t/110
t/110
t/110
t/110
b/289
b/289
b/289
b/289
b/289
b/289
b/289
b/289
* In sample K-5 the Pd precursor used was : Pd(C2H3O2)2.
* In samples C-2, C-3 and D-2 0.75, 1.5 and 0.75 mmol of Pd(C5H7O2)2 were used respectively.
** Solvents: b= benzyl ether; t= toluene.
Figure S1. Deconvolution of (111) diffraction peak for samples A-F.
The crystallite sizes have been calculated by the deconvolution of the (111) diffraction
peak and using the Scherrer equation:
𝐷=
𝐾𝜆
𝐵𝑒𝑠𝑡𝑟𝑢𝑐 cos 𝜃
Where K is the shape factor (values ranging from 1 to 0.8 have been used depending on
the sphericity of the nanoparticles in the sample), Bstructure = Bobserved-Binstrumental is the
full width at half maximum, =(Kα1+Kα2)/2=1.5418Å, and θ is the peak position.
Table S2. Parameters obtained from (111) diffraction peak deconvolution and
calculated crystallite size using Scherrer equation.(*The uncertainty of calculation).
Sample
B obs.
[°2θ]
B inst.
[°2θ]
Peak pos.
[°2θ]
B struct. [°2θ]
Crystallite size
[nm] *(±σ)
A
B
C
D
E
F
1.366
1.395
2.855
1.618
1.852
2.382
0.120
0.120
0.120
0.120
0.120
0.120
40.295
40.261
39.994
40.436
40.159
40.516
1.246
1.275
2.735
1.498
1.732
2.262
6.0±0.2
6.3±0.2
2.9±0.2
5.3±0.2
4.3±0.2
4.2±0.2
Figure S2. FTIR spectra of pure dodecanetiol, oleylamine, oleic acid and PdFe
nanoparticles coated with ligands (sample C and F )
.
Model S1. Effective anisotropy constant, Keff, calculation within the Non-Interacting
Super-Paramagnetic (SPM) model.
In a set of uniaxial magnetic single domains of size D oriented at random, neglecting the dipolar
interaction, the effective anisotropy constant is proportional to the so-called blocking
temperature (𝑇𝑏 ):
𝐾𝑒𝑓𝑓 =
𝑘𝐵 ln⁡(𝜏𝑚 /𝜏0 )
𝑇𝑏
𝑉
(1)
𝑇𝑏 becomes a direct experimental measurement of the energy barrier between the two ground
states “up” and “down” of the particle magnetic moment (𝐾𝑉). In equation (1), 𝜏𝑚 is the
characteristic time of the experiment (time window) and 𝜏0 is the inverse of the natural
fluctuation rate of the particle magnetic moment.
In a measurement of DC magnetization ln⁡(𝜏𝑚 /𝜏0 ) ≈ 25 , so it follows that, assuming a set of
particles of identical size, the effective anisotropy constant can be directly deduced from 𝑇𝑏 as:
25𝑘𝐵
𝐾𝑒𝑓𝑓 = (
) 𝑇𝑏
𝑉
(2)
In such an ideal system 𝑇𝑏 coincides exactly with the maximum of the ZFC curve. When the
natural dispersion of sizes is taking into account, equation (2) turns into the following one:
25𝑘𝐵
𝐾𝑒𝑓𝑓 = (
) ⟨𝑇𝑏 ⟩
𝑉
(3)
where ⟨𝑇𝑏 ⟩ is the average of the blocking temperatures of the population, each one depending on
the size of a given particle. It is to note that ⟨𝑇𝑏 ⟩ does not lie at the maximum of the ZFC, in a
set of particles with some dispersity.
In order to calculate the average blocking temperature, determination of the 𝑓(𝑇𝑏 ) (proportional
to the energy barrier distribution) is necessary. It can be obtained experimentally from the
ZFC/FC measurement of magnetization under a sufficiently small applied field, considering
that:
𝑓(𝑇𝑏 )~
𝑑
(𝑀 − 𝑀𝑍𝐹𝐶 )
𝑑𝑇 𝐹𝐶
(4)
In this way and after normalizing the derivative of the difference between ZFC and FC with the
condition: ∫ 𝑓(𝑇𝑏 )𝑑𝑇𝑏 = 1, the average blocking temperature is given by:
∞
⟨𝑇𝑏 ⟩ = ∫ 𝑇 𝑓(𝑇𝑏 )𝑑𝑇𝑏
0
(5)