Effect of PVP on the synthesis of high-dispersion core–shell barium-titanate–polyvinylpyrrolidone nanoparticles

Figures & data

Table 1 Reaction conditions and results of BT–PVP synthesis using solutions with different PVP concentrations. The molecular weight of PVP was 10,000 g/mol.

Sample	PVP concentration (g/L)	Crystallite size^a (nm)	Lattice parameter (Å)	Particle size^b (nm)	Shell thickness^c (nm)
BT-C1	0	48.7	4.0404	205	0
BT-C2	25	49.0	4.0401	191	2.0
BT-C3	50	44.5	4.0428	141	4.8
BT-C4	100	43.3	4.0408	130	2.8
BT-C5	200	40.1	4.0409	120	2.6
BT-C6	300	39.2	4.0405	102	3.6
BT-C7	350	51.8	4.0399	116	6.5
BT-C8	450	50.7	4.0423	97	7.7

a Calculated using Scherrer’s equation.

b Measured by FE-SEM.

c Calculated using Eq. (2)(2) in this paper.

Table 2 Reaction conditions and results of BT–PVP synthesis using solutions containing PVP with different molecular weights. The concentration of PVP was 50 g/L.

Sample	PVP molecular weight (g/mol)	Crystallite size^a (nm)	Lattice parameter (Å)	Particle size^b (nm)	PVP length (nm)	Shell thickness^c (nm)
BT-W1	2,500	45.5	4.0469	143.8	3	0.5
BT-W2	10,000	44.5	4.0428	141.0	12	4.5
BT-W3	40,000	43.1	4.0433	143.5	47	3.7
BT-W4	130,000	42.2	4.0444	151.5	152	6.2
BT-W5	360,000	42.3	4.0432	132.2	420	4.1

a Calculated using Scherrer’s equation.

b Measured by FE-SEM.

c Calculated using Eq. (2)(2) in this paper.

Fig. 1 (a) XRD patterns and (b) FE-SEM images of BT–PVP prepared at various PVP concentrations: (i) 0, (ii) 25, (iii) 100, and (iv) 450 g/L.

Fig. 2 (a) TEM image of BT–PVP prepared in 100 g/L PVP reaction solution. (b) TEM image of the BT–PVP particle marked by the red arrow point in (a). (c) HRTEM image of a part of the particle shown in (b). (d) Enlarged HRTEM image and (e) corresponding fast Fourier transform (FFT) pattern of the area enclosed by the red rectangle in (c).

Fig. 3 (a) Effect of PVP concentration on the size of particles measured by FE-SEM and the size of crystallites estimated from the XRD peak corresponding to reflection from the (110) plane. (b) Effect of PVP concentration on the average number of crystallites in an agglomerated particle of BT–PVP.

Fig. 4 (a) DLS patterns of BT–PVP prepared at different concentrations of PVP: (i) 0, (ii) 25, (iii) 100, and (iv) 450 g/L. (b) Relationship between the particle size and PVP concentration. The particle size was measured FE-SEM and DLS respectively.

Fig. 5 (a) XRD patterns and (b) FE-SEM images of BT–PVP prepared from reaction solutions containing different molecular weight of PVP (i) 2500, (ii) 10,000, (iii) 130,000, and (iv) 360,000 g/mol.

Fig. 6 (a) Effect of PVP molecular weight on the size of particles measured by FE-SEM and the size of crystallites estimated from the XRD peak corresponding to reflection from the (110) plane. (b) Effect of PVP molecular weight on the average number of crystallites in an agglomerated particle of BT–PVP.

Fig. 7 (a) DLS patterns of BT–PVP prepared from solutions containing PVP with different molecular weight of PVP (i) 0, (ii)10,000, (iii)130,000, and (iv) 360,000 g/mol. (b) Relationship between particle size and molecular weight of PVP. The particle size was measured either by FE-SEM or DLS.

Fig. 8 (a) Relationship between pH and ζ-potential of three different types of nanoparticles: BT prepared without PVP; BT–PVP prepared from solution containing PVP with molecular weight of 2500 and 10,000 g/mol. FE-SEM images of an aqueous suspension containing 1 wt% nanoparticles of BT–PVP prepared with 10,000 g/mol PVP(b) and BT prepared without PVP(c).

Fig. 9 (a) Effect of PVP concentration on the size of particles and cores and the shell thickness. (b) Effect of PVP molecular weight on the size of particles and cores and the shell thickness.

Fig. 10 Schematic illustration of the growth of crystallites and particles and the dispersion mechanism of BT–PVP prepared from solutions containing PVP with different concentrations and molecular weights.