Preparation and positive temperature coefficient of resistivity behavior of BaTiO3–BaBiO3–Bi0.5Na0.5TiO3 ceramics

Abstract

In this study, as a promising material for leadfree positive temperature coefficient of resistivity ceramics, (1 -x -y)BaTiO 3 -xBaBiO 3 -y(Bi 0.5 Na 0.5 )TiO 3 (x = 0.001, 0.002, 0.003; y = 0, 0.002, 0.004, 0.006, 0.01) samples were prepared by the conventional mixed oxide method. All the samples were sintered in air atmosphere for 1 h. X-ray diffraction, scanning electron microscope and resistivity-temperature measurement were used to study the crystal structure, microstructure and resistivitytemperature dependence. The results revealed that proper amount of BaBiO 3 doping not only decreased the room temperature resistivity, but also increased the Curie temperature. Its optimal doping content was finally chosen as 0.2 mol%. And with an increase of BNT content, both the Curie temperature and the room temperature resistivity increased. When BaBiO 3 = 0.2 mol%, BNT = 0.6 mol%, the Curie temperature was 153°C and the room temperature resistivity was 1512 X cm. When the BNT content increased to 1 mol%, the Curie temperature increased to 157°C but the room temperature resistivity increased sharply to 4.0 9 10 5 X cm.

Enhanced aging behaviors and electric thermal stabilities in 0.75BiFeO3–0.25BaTiO3 piezoceramics by Mn modifications

“…When the content of Mn excessive, Mn will enter the grain boundaries of the ceramic to restrain the growth of ceramic grains. 27,28 The piezoelectric property and ferroelectric property of 0.75BF-0.25BT ceramics were improved by Mn doping at room temperature, as shown in Table 1. And those electrical properties reached the peak values at x = 1.0.…”

Enhanced insulating and piezoelectric properties of BiFeO3‐BaTiO3‐Bi0.5Na0.5TiO3 ceramics with high Curie temperature

“…The volatilization of Bi 3+ is more serious than Na + since the melting point of Bi 2 O 3 (ca 820°C) is much lower than that of Na 2 O (ca 1275°C). The redundant Na + tended to distribute at the grain boundaries and inhibit the grain growth . As increasing x , the inhibiting effect increases, and is predominant at x = 0.07, leading to refined grain.…”

“…The grown grain is attributed to the increased Bi 25 FeO 40 which would form liquid phase and benefit the grain growth in sintering . The decreased grain size is caused by the redundant Na + at the grain boundaries, which would inhibit the grain growth . BNT was unstable and could decompose into Bi 2 O 3 and Na 2 O during the sintering .…”

“…BNT ceramic is a representative perovskite ferroelectric material with excellent ferroelectric property ( P r = 38 μC/cm 2 ) and high T C of 320°C . It was found that the resistivity of BT can be significantly increased by two orders of magnitude after adding BNT . It is reasonable to infer that the resistivity of BF‐BT ceramics can be increased by the addition of BNT to form a ternary solid solution, which would benefit the poling and piezoelectric property.…”

“…On the other hand, adding the third number (SrZrO 3 , Bi(Zn 0.5 Ti 0.5 )O 3 , Bi(Mg 1/2 Ti 1/2 )O 3 and so on) into BF and ion substitution for Fe 3+ and/or Bi 3+ by Sc 3+ , Sm 3+ or Dy 3+ have been tried to enhance the insulating property in BF‐BT ceramics . But there were few reports that relate to the addition of the third number into BT to enhance the insulating property in BF‐BT ceramics. BNT ceramic is a representative perovskite ferroelectric material with excellent ferroelectric property ( P r = 38 μC/cm 2 ) and high T C of 320°C .…”