Praseodymium substituted lanthanum orthoniobate: Electrical and structural properties

Terbium Substituted Lanthanum Orthoniobate: Electrical and Structural Properties

“…σT = σ 0 e − Ea kT (5) The change of slope of the plots observed at temperatures about 500 • C is related to the phase transition between the scheelite and fergusonite structures. Such behavior was observed before in many LaNbO 4−δ -based materials [13,15,28,35]. The influence of the terbium content on the apparent activation energies of total conductivities (Table 2) is complex.…”

“…In the following years, multiple dopants have been introduced both into the lanthanum (e.g., by calcium [14], magnesium [15], or strontium [16][17][18][19]) and niobium (e.g., by vanadium [20][21][22], antimony [23][24][25], arsenic [26], or cobalt [27]) sublattices. Recently, we also reported the influence of co-doping, using praseodymium as a rare earth dopant and calcium as an acceptor dopant in the lanthanum sublattice, on these system properties [28]. The presence of a mixed 3+/4+ cation in the lanthanum sublattice leads to enhanced electronic conductivity and yielding a mixed proton-electron conductor.…”

Effects of Sn Doping and A‐Site Deficiency on the Phases and Electrical Conductivities of the High‐Temperature Proton Conductor LaNbO4

“…To this end, many researchers have been devoted to this topic through a doping strategy. [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] For example, using a secondary dopant Sb [24,30] or As [32] in the Nb sublattice can stabilize the tetragonal phase to room temperature, which can therefore obviously enhance the proton conductivity in the low-temperature range. The effects of some other elements, such as Ga, Ge, Si, B, Ti, Zr, P, Al, or Mn, substituting for the B-site Nb atoms on the phase and electrical properties of LaNbO 4 , were also investigated.…”

“…In addition, the effects of partial substitution of La 3þ for isovalent lanthanides, such as Ce, Pr, Nd, Sm, Gd, Yb, and Tb, on the thermal and electrical properties have also been reported. [20,29,31,33,35] Unfortunately, this also did not benefit the enhancement of the proton conductivity and resulted in an even lower conductivity than that of the single lanthanide La 3þ ions on the A-site.…”

Fabrication and Structural Properties of LaNb1‐xAsxO4 Ceramics

“…Thermal incompatibility, which yields from a change of the expansion coefficient can lead to strain, cracking or even a total failure of the electrochemical cell . Another parameter that changes with the transition is the activation energy of protonic conductivity, which lowers when the system has a higher order of symmetry . This affects the protonic conductivity of the material.…”