Microstructural characteristics and grain growth kinetics of Pr6O11 Doped SnO2-based varistors

SnO 2 Promoted by Praseodymia: Novel Catalysts for CO Oxidation

“…All the praseodymia promoted samples have higher surface areas than SnO 2 , which are 20, 23 and 41 m 2 /g for SnPr01, SnPr02 and SnPr03, respectively. The same phenomenon was also observed by Bahrevar and co-workers [29]. Though Pr 6 O 11 has higher surface area than pure SnO 2 , SnPr01 and SnPr02, its activity is the lowest among all of the samples, indicating that the Pr 6 O 11 itself has limited contribution for the reaction.…”

Improvement in the non-linear electrical characteristics of the SnO2·Co2O3·Ta2O5 varistor material with Pr6O11 additive

“…The increased electrical nonlinearity trend with addition of Pr ions in this work is quite different with those reported in Refs. [7,8]. The related mechanism is not clear.…”

“…First, the addition of minor CoO, MnO or ZnO into the SnO 2 -based systems was found to densify pure SnO 2 ceramic powder [2][3][4]. Some other dopants, such as Nb 2 O 5 , Bi 2 O 3 , Ta 2 O 5 etc., have to be added into the Sn-Co/Mn/Zn-O system to either control the microstructure development or to enhance the electrical behavior of the varistor [4,[5][6][7][8][9]. Recently, praseodymium oxides (Pr 2 O 3 , Pr 6 O 11 , etc.)…”

“…may not only inhibit the grain growth but also improve the electrical properties of the SnO 2 -based ceramic. It has been studied for the effects of the addition of various amounts of Pr 6 O 11 on SnO 2 -based varistors containing cobalt and niobium oxides [8]. Also, Wang et al investigated the nonlinear electrical characteristics and dielectric properties of the SnO 2 -Co 2 O 3 -Ta 2 O 5 system doped with Pr 2 O 3 [7].…”

Microstructure and Nonohmic Properties of SnO2-Ta2O5-ZnO System Doped with ZrO2

“…Through a series of studies on SnO 2 -based varistors for decades, it is well known that an excellent SnO 2 varistor system consists of three kinds of dopants: resistance reducers (varistor forming oxide, VFO), densifiers, and modifiers, respectively [5]. To date, the commonly applied VFOs are Nb 5+ [6–8] or Ta 5+ [9–11], which possesses high chemical valence and is soluble in SnO 2 grains to decrease the grain resistivity; the densifier is insoluble ion of low chemical valence that will segregate at SnO 2 grain boundary regions to promote the densification by producing oxygen vacancies, for example, Co 2+ [4, 6, 7, 9, 11], Mn 2+ [12, 13], and Zn 2+ [8, 14], and the modifiers can effectively improve the electrical properties of the varistors, such as Cr 3+ , Fe 3+ , Cu 2+ , and rare earth elements [6–9, 15, 16].…”