Facile synthesis of lanthanum carbonate octahydrate and lanthanum oxide nanoparticles by sonochemical method: systematic characterizations
Authors: Imsong Sentienla , Imsong Punazungba , Hazarika Swapnali , Indira Devi M. 
Published: March 2024

Abstract
This study could present the size and morphology of two synthesized nanoparticles (NPs) by observing their smallest possible dimensions. Lanthanum carbonate nanoparticles were synthesized by sonochemical method through the interaction of lanthanum acetate hydrate and sodium carbonate in an aqueous medium with a probe sonicator. After rigorous washing followed by drying, the La2(CO3)3·8H2O(S1) NPs were calcined at a temperature of 600 °C to obtain lanthanum oxide nanoparticles (S2). Both NPs were characterised through various instrumental techniques. PXRD study showed orthorhombic with space group of Pccn (56) and hexagonal phases with space group of

P

3
‾

m
1

$P\overline{3}m1$

(164) for S1 and S2 respectively whose morphology and elemental analysis were studied through FESEM and EDX. High resolution TEM image of La2(CO3)3·8H2O and La2O3 showed spherical shapes of the nanoparticles. Further study of XPS and FTIR conveyed detailed information of both nanoparticles whose TGA-DSC showed three step decomposition curves. The size and morphology of the synthesized nanoparticles have been found to have a distinct morphology and are found comparatively smaller in size than those observed in the earlier reported works (Table 1

Table 1:

Comparative study of synthesized lanthanum carbonate and lanthanum oxide NPs with various techniques applied by other researchers.

Sl. no.
Name of NPs
Methods
Conditions
Size of NP
Reference

1
La2(CO3)3·8H2O
Sonochemical method
Time: 25 min

XRD:
Pccn (56) a = 8.9840 Å
b = 9.5800 Å
c = 17.0000 Å
This work

Temperature: 301 K

Size: 24.102 nm

Starting materials:(a) La(CH3COO)2: 0.050 M(b) Na2CO3:0.050 M

TEM:
Size: 4–30 nm

La2(CO3)3

Reverse micelles
Time: 1 h

XRD:
Size: nanoparticles absent
[20]

Temperature: 303 K

Starting materials:(a) Triton X-100(b) Cyclohexane(c) n-butylalcohol(d) La(NO3)3(aq)
e) NaCO3(aq)

La2(CO3)3·8H2O
Hydrothermal
Time: 2–5 days

XRD:
Pccn a = 8.984 Å
b = 9.580 Å
c = 17.00 Å
[21]

Temperature: 773 K

Size: nanoparticles absent

Prepared by slow hydrolysis of La(CCl3COO)3

La2(CO3)3·1.4H2O
Hydrothermal
Time: 1 h 30 min
Structure unknown
[22]

Temperature: 368 K

Starting material:(a) La2O3
(b) HNO3
(c) Urea

La2(CO3)3·1.7H2O
Sonochemical
Time: 30 min

XRD:

a = 8.990 Å
c = 9.675 Å
[23]

Temperature: not specified

Size: not specified

(a) La(OAC)3
(b) Na2CO3

TEM:
Size: 25–35 nm

Concentration:(a) La(OAC)3: 0.051 M(b) Na2CO3: 0.251 M

La2(CO3)3·5H2O
Hydrothermal
Time:

XRD:

Pbca a = 9.0167 Å
b = 12.842 Å
c = 9.6331 Å
[24]

Temperature:

Size: not specified

Starting materials:(a) La2O3
(b) HCl(c) Na2CO3

La2(CO3)3·3.4H2O
Hydrothermal
Time: 3–4 h

XRD:

P21212
a = 9.57 Å
b = 12.65 Å c = 8.94 Å
[25]

Temperature: 298–308 K

Size: not specified

Starting materials:(a) LaCl3
(b) NH4HCO3

2
La2O3

Thermal decomposition
Time: 2 h

P3m1
a = 3.973 Å
b = 3.9373 Å
c = 6.129 Å
[26]

Temperature: 1073 K

Size: 15 nm

Starting material: La(OH)3 nanorods

TEM:
Size: 23 nm

La2O3

Thermal decomposition
Time: 2 h

XRD:
a = 11.347 Å
[23]

Temperature: 873 K

Size: 30 nm

Starting material:La2(CO3)3·1.7H2O

TEM:
Size: 30 nm

La2O3

Thermal decomposition
Time: not specified
Not specified
[27]

Temperature: 1198 K

Starting material:(a) La(NO3)3·9H2O(b) NH4HCO3

La2O3

Thermal decomposition
Time: 4 h
Not specified
[28]

Temperature: 1073 K

Starting material: La(OH)3

La2O3

Thermal decomposition
Time: 2 h

P

3
‾

m
1

$P\overline{3}m1$

a = 3.973 Å
b = 3.9373 Å
c = 6.129 Å
This work

Temperature: 873 K

XRD:
Size: 43.26 nm

Starting material: La2(CO3)3·8H2O

TEM:

Size: 17–34 nm

).