High-performance electrical properties of La-based perovskite ceramics for the functional phase of thick film resistors

Highlights: • Low absolute TCR values could be achieved in the range of x = 0.4–0.8 and zero TCR could be realized around 0.6 < x < 0.8. • The ceramic of 0.6LSCN + 0.4LCNZ showed the best performances: conductivity = 1923 S/cm, TCR = 379.54 ppm/°C, and ρ = 95.05%. • The composite ceramics of LSCN + LCNZ are potentially economical materials for thick film resistors without glass phase. -- Abstract: In order to explore an economical functional phase alternative material for thick film resistors, the crystal structure, microstructure, and electrical properties of (1-x)La_0.5Sr_0.5Co_0.96Ni_0.04O_3-δ + xLaCo_0.4Ni_0.58Zn_0.02O₃ (x = 0.0–1.0) composite ceramics were studied through solid-state reaction experiments. The composite ceramics were characterized by x–ray diffraction, scanning electron microscopy, energy dispersive x–ray spectroscopy, X-ray photoelectron spectroscopy, and DC four–probe method. Results suggested that the main phases of La_0.5Sr_0.5Co_0.96Ni_0.04O_3-δ and LaCo_0.4Ni_0.58Zn_0.02O₃ were formed, along with a small part of impurity phases. The addition of LaCo_0.4Ni_0.58Zn_0.02O₃ to La_0.5Sr_0.5Co_0.96Ni_0.04O_3-δ decreased the electrical conductivity and changed the temperature coefficient of resistance from positive to negative. Zero temperature coefficient of resistance could be achieved around 0.6 < x < 0.8 and relatively low absolute temperature coefficient of resistance values could be obtained for the samples of 0.4 ≤ x ≤ 0.8. The ceramic of 0.6La_0.5Sr_0.5Co_0.96Ni_0.04O_3-δ + 0.4LaCo_0.4Ni_0.58Zn_0.02O₃ showed the optimal performances of conductivity = 1923 S/cm, temperature coefficient of resistance = 379.54 ppm/°C, and relative density = 95.05%.