weight, N is Avogadro's number, and V is the unit cell volume as
determined from X-ray analysis. In this work, the lattice parameters
of NCZF and BT (as shown in Table 1 ), used to calculate their unit
cell volumes, were determined from the XRD patterns of 2 wt%
Bi
2
O
3
doped NCZF and 4.5 wt% Li
2
CO
3
-V
2
O
5
doped BT, respectively.
Accordingly, the XRD density values of doped NCZF and BT, calcu-
lated from equation (2) and shown in Table 1, can be chosen as
r
fi
and
r
ci
, respectively. Thus, theoretical density values of composites
sintered at a certain temperature (as shown in Table 2 )were
determined when XRD density values of NCZF and BT sintered at
this temperature were selected from Table 1 and substituted in
equation (1). The relative density of all composite samples, which
listed in Table 2, is in the range of 96.1%e99.5%. In particular,
composites sintered at 900
C have good densification with the
relative density value in the range of 97.1%e99.4%, which is better
than two other composite systems [28,29] (Ba
0.6
Sr
0.4
TiO
3
-NiCuZn
with 94.5%e97%, and Bi
4
Ti
3
O
12
-NiCuZn with 94.9%e96.4%) pre-
pared at same temperature. Furthermore, relative density values of
Table 1
Lattice parameters and density of NCZF doped with Bi
2
O
3
and BT doped with Li
2
CO
3
-V
2
O
5
.
Sample/Sintered
temperature
Lattice parameters (Å) XRD density
r
fi
,
r
ci
(g/cm
3
) Measured density
r
m
(g/cm
3
)
NCZF 900
Ca¼8.377 5.369 5.328
950
Ca¼8.384 5.355 5.303
1000
Ca¼8.365 5.392 5.275
BT 900
Ca¼4.002, c ¼ 4.041, c/a ¼ 1.0097 5.986 5.647
950
Ca¼3.993, c ¼ 4.031, c/a ¼ 1.0095 6.026 5.673
1000
Ca¼4.003, c ¼ 4.043, c/a ¼ 1.01 5.978 5.657
Fig. 1. X-ray diffraction patterns for samples sintered at 900
C, 950
C, and 1000
C.
Fig. 2. Density of composites sintered at 900
C, 950
C, and 1000
C as a function of BT
content (x), (a) a series of maximum density values chosen from composites sintered at
different sintering temperatures; (b) density of each composite sintered at 900
C and
950
C.
W. Ling et al. / Journal of Alloys and Compounds 750 (2018) 479e489 481