Effect of dopant

Fig. 4. Effect of dopant additions on the resistivity versus temperature behavior of BaTiO PTCR ceramics. A, undoped B, doped with 0.134 mol % Cr ...

The thermal decomposition reactions of KN3, T1N3, and AgN3 have been studied in the corresponding halide matrices [301]. The formation of NCCT from trapped C02 was described and labelling with ISN established that only a single end-N atom of the azide ion was involved in NCO formation. The photodecomposition of PbN6 and the effects of dopants have been followed [302] by the changes produced in the near and the far infrared. 

E.C. Akubuiro, and X.E. Verykios, Effects of dopants on performance of metal crystallites 2. Further characterization of doped supports and catalysts, J. Catal. 113, 106-119(1988). 

Undoped, Mn, and Pr-doped ZnS namopartides synthesized by wet chemiral mdhod were optically annealed in air or vacuum. PL emission inoeas with annulling time. This increase is attributed to the photo-oxidation, enhancanent in the crystal quality, and diffiision of the luminescent ions. PL intensity of nanoparticles annealed in air increased more significantly due to the photo-oxidation compared with the nanoparticles annealed in vacuum. Mn and Pr-codoped ZnS nanoparticles emitted white light due to the effects of dopants. The optical annealing enhanced the emission intensity. 

Guan, J., S.E. Dorris, U. Balachandran, and M. Liu, The effects of dopants and A B site nonstoichiometry on properties of perovskite-type proton conductors, /. Electrochem. Soc., 145,1780,1998. 

It has been noted that the conductivity and activation energy can be correlated with the ionic radius of the dopant ions, with a minimum in activation energy occurring for those dopants whose radius most closely matches that of Ce4+. Kilner et al. [83] suggested that it would be more appropriate to evaluate the relative ion mismatch of dopant and host by comparing the cubic lattice parameter of the relevant rare-earth oxide. Kim [84] extended this approach by a systematic analysis of the effect of dopant ionic radius upon the relevant host lattice and gave the following empirical relation between the lattice constant of doped-ceria solid solutions and the ionic radius of the dopants. 

Chatteijee, A. 2006. A reactivity index study to rationalize the effect of dopants on Bronsted and Lewis acidity occurring in MeAlPOs. J. Mol. Graphics Model. 24 262-270. 

Higgins 171) warned against misinterpretation of promoter effects in catalysts prepared by incipient wetness and coprecipitation using acidic solutions. Acidic solutions can cause the formation of V0P04 2H20, which has a detrimental effect on the catalyst performance that can be mistakenly attributed to the promoter. These authors recommend that these methods of introducing promoters be used with care, and in particular they recommended that the acidity of the impregnation solution be carefully monitored. It is also clear that to imderstand the promotional effects of dopants, variables such as preparation methods and surface area effects must be taken into accoimt. 

Equation 9 quantifies the effects of dopant concentrations on the temperature required for the onset of martensite formation, Mg. The greatest effects are seen for the austenite-forming elements of C, Mn, and Ni where even small concentrations result in a sharp decrease in Mg. Whereas pure y-iron may be converted to martensite at temperatures in excess of 500°C, hypereutectoid steel is not transformed to martensite until a temperature of ca. 160°C is reached during quenching. At carbon concentrations above 0.7%, martensite is still being formed at temperatures well below 0°C. Hence, high-C steels must be quenched in low-temperature media e.g., dry ice/acetone, liquid nitrogen) to ensure full conversion of austenite to martensite. 

Because of the difficulty in controlling the impurities in glass, the development of a single glass filter with closely defined optical characteristics may be economically prohibitive. When one also considers the positive and negative effects of dopants on solarization and the desire by companies to differentiate products, progress toward this goal on an international scale may be very slow. 

The effect of dopant-induced-metal-support interactions (DIMSI) studied for years by Verykios and co-workers [97]. 

FIGURE 8.52. The effect of dopant concentration on the PS density. After Arita and Sunahama. (Reproduced by permission of The Electrochemical Society, Inc.)... 

La3+155 q 3+156 fQj. Ni-Mo/Al203 Group IA and IIA ions, Group IIA ions/ The structural effect of dopant ions (Na, Mg, and Zn + 97 y jg partly to neutralize acid sites on the catalyst surface and partly to displace or from the AI2O3 lattice to the surface, so... 

J. Maier, Mass transport in the presence of internal defect reactions-concept of conservative ensembles I, Chemical diffusion in pure compounds. /. Am. Ceram. Soc., 76(5) (1993) 1212-1217 II, Evaluation of electrochemical transport measurements, ibid., 1218-1222 III, Trapping effect of dopants on chemical diffusion, ibid., 1223-1227 IV, Tracer diffusion and intercorrelation with chemical diffusion and ion conductivity, ibid., 1228-1232. 

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