Facile synthesis of lanthanum carbonate octahydrate and lanthanum oxide nanoparticles by sonochemical method: systematic characterizations

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 La 2 (CO 3 ) 3 ·8H 2 O(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 <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <m:mrow> <m:mi>P</m:mi> <m:mover accent="true"> <m:mn>3</m:mn> <m:mo>‾</m:mo> </m:mover> <m:mi>m</m:mi> <m:mn>1</m:mn> </m:mrow> </m:math> P3̄m1 (164) for S1 and S2 respectively whose morphology and elemental analysis were studied through FESEM and EDX. High resolution TEM image of La 2 (CO 3 ) 3 ·8H 2 O and La 2 O 3 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 La 2 (CO 3 ) 3 ·8H 2 O 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(CH 3 COO) 2 : 0.050 M (b) Na 2 CO 3 :0.050 M TEM : Size : 4–30 nm La 2 (CO 3 ) 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(NO 3 ) 3(aq) e) NaCO 3(aq) La 2 (CO 3 ) 3 ·8H 2 O 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(CCl 3 COO) 3 La 2 (CO 3 ) 3 ·1.4H 2 O Hydrothermal Time: 1 h 30 min Structure unknown [22] Temperature: 368 K Starting material: (a) La 2 O 3 (b) HNO 3 (c) Urea La 2 (CO 3 ) 3 ·1.7H 2 O 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) Na 2 CO 3 TEM : Size: 25–35 nm Concentration: (a) La(OAC) 3 : 0.051 M (b) Na 2 CO 3 : 0.251 M La 2 (CO 3 ) 3 ·5H 2 O Hydrothermal Time: XRD: Pbca a = 9.0167 Å b = 12.842 Å c = 9.6331 Å [24] Temperature: Size : not specified Starting materials: (a) La 2 O 3 (b) HCl (c) Na 2 CO 3 La 2 (CO 3 ) 3 ·3.4H 2 O Hydrothermal Time: 3–4 h XRD: P 2 1 2 1 2 a = 9.57 Å b = 12.65 Å c = 8.94 Å [25] Temperature: 298–308 K Size : not specified Starting materials: (a) LaCl 3 (b) NH 4 HCO 3 2 La 2 O 3 Thermal decomposition Time: 2 h P 3 m 1 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 La 2 O 3 Thermal decomposition Time: 2 h XRD : a = 11.347 Å [23] Temperature: 873 K Size: 30 nm Starting material: La 2 (CO 3 ) 3 ·1.7H 2 O TEM : Size : 30 nm La 2 O 3 Thermal decomposition Time: not specified Not specified [27] Temperature: 1198 K Starting material: (a) La(NO 3 ) 3 ·9H 2 O (b) NH 4 HCO 3 La 2 O 3 Thermal decomposition Time: 4 h Not specified [28] Temperature: 1073 K Starting material: La(OH) 3 La 2 O 3 Thermal decomposition Time: 2 h <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <m:mrow> <m:mi>P</m:mi> <m:mover accent="true"> <m:mn>3</m:mn> <m:mo>‾</m:mo> </m:mover> <m:mi>m</m:mi> <m:mn>1</m:mn> </m:mrow> </m:math> P3̄m1 a = 3.973 Å b = 3.9373 Å c = 6.129 Å This work Temperature: 873 K XRD : Size : 43.26 nm Starting material: La 2 (CO 3 ) 3 ·8H 2 O TEM: Size : 17–34 nm ).