The preparation and characterizationof phosphoroustungsten bronzes doped with lithium, magnesium and europium ions.

[Z. Nedić]

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fiziĉka hemija - fiziĉka hemija ĉvrstog stanja / physical chemistry - physical chemistry of solid state

Heteropoli kiseline ĉija je opšta formula H3+xAM12040∙nH20 (x=0-1; A=P, Si, B, As, Ge; M=Mo, W; n=30-6) imaju poseban znaĉaj kao novi materijali sa velikim provodljivostima. MeĊu njima posebnu paţnju zasluţuje 12-volframfosforna (29-WPA) kiselina. U ovom radu prikazana je studija o kalcinaciji/dehidrataciji i strukturnim modifikacijama WPA hidrata od sobne temperature do 1150 0C. Mi smo takoĊe ispitivali prateće modifikacije protonskih vrsta tokom procesa dehidratacije kao i sintezu fosforvolframove bronze i njihove polimorfne transformacije. Dizajniranje materijala saglasno teorijski dobro definisanim oĉekivanjima, ima izuzetan znaĉaj za preciznije definisanje strukture materijala i uslove njihove sinteze, koji omogućuju organizovanje takve strukture na predvidiv naĉin. Samo dizajniranje strukture na svim nivoima od osnovnog, saglasno našim eksperimentalnim i teorijskim modelnim istraţivanjima daje rezultate koji pokazuju izuzetnu meĊusobnu saglasnost teorijskih oĉekivanja i eksperimentalnih rezultata. U ovom radu je pokazano kako sprej piroliza sa ultrazvuĉnom pobudom moţe biti iskorišćena za dobijanje sfernih prahova fosforvolframovih bronzi dopiranih jonima litijuma, magnezijuma i europijuma, polazeći odH3PW12O40∙29H2O (WPA) kao prekursora. Ovi prahovi imaju nanostrukturni dizajn, sa srednjom veliĉinom ĉestice od 1 μm, koja se sastoji iz subĉestica veliĉine od 30 do 80 nm.

Heteropolyacids, with a general formula ofH3+xAM12040∙nH20 (x=0-1; A=P, Si, B, As, Ge;M=Mo, W; n=30-6) are of special interest as newmaterials because of their high conductivities. Among them special attention deserves the 12-tungstophosphoric (29-WPA) acid. In this paper we report a study of the calcination/dehydration and structural modification of WPA hydratesfrom room temperature to 11500C. We alsoinvestigated the accompanying modifications of theprotonic species during the dehydration process aswell as the synthesis of phosphorus-tungsten bronzesand their polymorphous transformations. Designing of materials according to theoretically well determined predictions is of exceptional importance for more precise definition of materials structures, and synthesis conditions which provide organizationof such structures in a clear and predictable way. Only designing of structures at all levels from the basic ones according to our research and theoretical models, gives results that show excellent agreement between theoretical expectations and experimental observations. In this paper it is shown how the ultrasonic spray pyrolysis can beused to obtain fine spherical powder particles of phosphoroustungsten bronzes doped with lithium, magnesium and europium ions, from the feeding solution WPA-29 (H3PW12O40∙29H2O). This powder has nanostructured design with average particle size1 μm, and subparticles 30-80 nm.

heteropoli kiseline, fazne transformacije, fosforvolframove bronze, sprej piroliza, modeliranje, strukturno dizajniranje i sub-dizajniranje

heteropoly acids, phase transformations, phosphoroustungsten bronzes, spray pyrolysis, modeling, structure design and sub-design.

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