Metal-semiconductor phase transition in hydrated powders of VO2 as influenced by adsorbed water, polyethylene glycol medium, and tetraethylammonium bromide additives
The opportunity of use of a 1H NMR method for study of the performances of phase transition the metal - semiconductor in crystalline VO2 is considered. The influence of the adsorbed water, polyethylene glycol medium and presence of the tetraethylammonium bromide additives on the phase transition per...
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| Date: | 2001 |
|---|---|
| Main Authors: | , , , , , , , , , |
| Format: | Article |
| Language: | English |
| Published: |
Chuiko Institute of Surface Chemistry National Academy of Sciences of Ukraine
2001
|
| Online Access: | https://surfacezbir.com.ua/index.php/surface/article/view/63 |
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Surface| _version_ | 1869291150746058752 |
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| author | Turov, V. V. Gorbik, P. P. Laguta, I. V. Shulga, O. V. Semchuk, O. Yu. Grechko, L. G. Ogenko, V. M. Chuiko, A. A. Willander, M. Karlsteen, M. |
| author_facet | Turov, V. V. Gorbik, P. P. Laguta, I. V. Shulga, O. V. Semchuk, O. Yu. Grechko, L. G. Ogenko, V. M. Chuiko, A. A. Willander, M. Karlsteen, M. |
| author_institution_txt_mv | [
{
"author": "V. V. Turov",
"institution": "Інститут хімії поверхні НАН України"
},
{
"author": "P. P. Gorbik",
"institution": "Інститут хімії поверхні НАН України"
},
{
"author": "I. V. Laguta",
"institution": "Інститут хімії поверхні НАН України"
},
{
"author": "O. V. Shulga",
"institution": "The University of Toledo"
},
{
"author": "O. Yu. Semchuk",
"institution": "Інститут хімії поверхні НАН України"
},
{
"author": "L. G. Grechko",
"institution": "Інститут хімії поверхні НАН України"
},
{
"author": "V. M. Ogenko",
"institution": "Інститут хімії поверхні НАН України"
},
{
"author": "A. A. Chuiko",
"institution": "Інститут хімії поверхні НАН України"
},
{
"author": "M. Willander",
"institution": "Chalmers University of Technology and Göteborg University"
},
{
"author": "M. Karlsteen",
"institution": "Chalmers University of Technology and Göteborg University"
}
] |
| author_sort | Turov, V. V. |
| baseUrl_str | |
| collection | OJS |
| datestamp_date | 2018-11-27T09:42:39Z |
| description | The opportunity of use of a 1H NMR method for study of the performances of phase transition the metal - semiconductor in crystalline VO2 is considered. The influence of the adsorbed water, polyethylene glycol medium and presence of the tetraethylammonium bromide additives on the phase transition performances is explored. The phenomenon of phase heterogeneity VO2 is revealed which is exhibited as simultaneous existence of semiconductor and metal phases. Presumably this kind of heterogeneity is stipulated by an adsorption of bromide ions on a surface of particles VO2. |
| first_indexed | 2025-09-24T17:44:40Z |
| format | Article |
| fulltext |
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MЕTAL.SЕ N{IC oг..{DUсТ oR PIIASЕ ТRA]\SITION INIIYDRATЕD PoWDЕRs oF vo2 As NFLUЕ}{CЕD BYADSORBЕD WATЕR, P0LYЕT}IYLЕI.IЕ GLYсOL
MЕDIUII{, AND TЕTRAЕTHYLAN{MOI{IUМ
BROII{IDЕ ADDITNЕS
V.V. Тurov', P.P.,Gorbikl, I.V. I,дgц1а', O.\,. Shulga2, o.\.u. SеmсhukI.L.G. Grесhko,, \'.}I ogenkol, A.A. Chuiko', NI] rvilluna..,,.;;;-^ '
М. Кarlstееn3
IInstitutе
Ч{,:ф,r Сhеmistry,' Nаtiotшl Асаc|еmу of Sсiеnсеs,
] 7 Gеn. Nаumov str., 0 3 ] б1 Kуiv' (/KRitмe'.
е -mаi l : u',,ф,ui1,nеm.1Гrееnеt. kiеv.uа
,,,
,o,,oo,,-^еnt,of
Сhеmi'try', й, uni,,,,iу, o/ Totеdo, Tolеdo ОH 13606, (JSА-DеpаrtmепI oJ Рhуsics, Сhаlmеrs {Jnivеrstф of Tе.9!уotogt апd Gotеnbo,g'U)iuersitу,
S-1 ] 29б, Gotеnborg, S||/EDЕN
Abstгaсt
Thе oppoпunitу of usе of a 1н }.пr,ш' mеthod for study of thе pегfoгmanсes of phasetгansition the mеtal - sеmiсonduсtоr in сгystallinе Voz is Ъonsidегеd. The influenсе of thеadsoфеd wateг, рolyеthylеnе glусol mejium and presеnсе of thе tеtraеthylammonium
bгomide additivеs o1'ч. рhase tгaлsition pеrfoгmancеs is е*jьгЬо Thе phеnomеnon ofphase hеtегogеneity Vou is геvеalеd whiсh is ехhibitеd as simultanеous ехistеnсe ofsеmiсonduсtoг and mеtal phasеs' P.геsumablу.this kind of ьеtегo!еnеity is stipulut"J by -adsorption of bгomidе ions on a suгfaсе of paпiсlеs Vo,.
Introduсtion
The mеtal-sеmiсonduсtoг phasе transition (МSPT) in vanadium dioхide is a fiгst-oгdег phasetгansition (РT) and bу this timе it has bееn studiеd in moге dеtail both for monoсry*"Ё unopolyсrystallinе films [1]' Howеvеr, up to thе prеsеnt th" ."u,u."mеnt of tempегatuгеpaгamеtеrs of PT in powdегs and suspеnsions of Vb2 has not bеen praсtiсally madе, whiсh isduе to thе diffiсцltiеs enсounteгеd whеn mеasuгing еlесtгiсal сonduсtivity uno.1.
"onсition
ora loosе еlесtгiс contaсt bеtwееn matегial paгtiсlеslМеanwhilе, thе pгoрегtiеs of substanсе indispеrsе statе maу substantially differ from thе bulk p.opепiеs of tLе substanсе, whiсh is ofpaпiсulaг impoгtanсе for thе devеlopmеnt of nеw сompositе matегials [2,3].Whеn invеstigating phase tгansitions in solidЪ, a йdе usе is madе of thе nuсlеar
m^agn€tiс геsonanсе spесtrosсopy [a]. This teсhniquе is сontaсtlеss, whiсh providеs a numbегof advantagеs ovеr standaгd mеasuгеmеnt methods foг еlесtгiсal сonduсtivity [5,6] Inpaпiсular, this tесhnique.allows onе to study phasе transitions in s.,spensions of solids with alow еlесtгiсal сonduсtivity of a dispeгsive mеdium, whегeas otheг mеthod, u,. p,u.tl"uity
untеnablе foг'suсh a study. Thе tесhniquе is basеd оn the dеpendеnое of magnеtiс pгop"пi.,,оf nuсlеi on thе phasе statе of a solid Bу now' th" rеsеa.сl,е' Ьi-|i'u'" tгansitions by thеNМR tесhniquе havе beеn сarгiеd оut pгеdominantlу Ьy mеasuгing tЬmpeгatuге dеpеndеnсеsof геlaхation timеs of nuсlei with a nonzero .nugn"ti. *o'.nГp]ьi, "K'-';nЬ.;^.;;tempегatuге of a samplе.undеr study appгoaсhеs thе valuе сhaгaсtегistic oг it' pьu,"transition, thе сurvеs of thе tеmpегatuге dеpеndеncеs of геlaхation timеs show ;
"i;".Бrеsolvеd infl есtion [4].
Tоdaу it is known that thе lv1sPT tеmpеratuге maу сhangе bесausе of еmеrgеnсе of an
еlеctriс сhargе on thе Vou suгГaсе' Suсh a сhargе maу apреar during surfaсе adsoгрtion of
somе tуреs of aсtivе molесulеs, in paгtiсulaг molесulеs of watег and ammоnia [7,8] as wеll as
during,intеraсtions of Voz paгtiсlеs with a polymегiс matriх [9'l0] Thеsе tуpеs of
intеraЪtions сan dесrеasе thе PT tеmрегaturе down to 320 K Howеvеr, thе sеaгсh foг nеw
sуstеms that would makе it possiblе to vary thе PT tеmpеraturе suffrсientlу quiсkly and
rЬvеrsiblу in a widег tеmpеIaturе intеrval геmains an urgеnt ргoblеm.
Aссording to a last invеstigations, геsеarсhеs into thе pгoрегtiеs of powdеrs and
susрепsions of Vбz сan bе сaпiеd out using a mеthod of 1н Nъш. spесtгosсoру of adsогbеd
*o.l"сul.s [11'12]. Thе mеthod is basеd on thе faсt that spесtгal сharaсtеristiсs of a substanсе
аt thе intей". of di,p..'е solids dеpеnd on thе substrаta matегial propеfiiеs. In thе prеsеnсе
ЬГ сonduсting matепЬls thе intеnsity of NМR signal for molесules of thе mateгial maу bе
lоwег thеn in thе сasе of diamagnеiiс mеdia bесausе оf thе paгtial absoгptiоn of thе radio-
fr"qu*n"у еneгgу by thе samрlе uolumе' Sсiеnсе thе сonduсtivitу of Vo: shaгply inсгеasеs at
thе.tеmрЬrat,',..*Ъгшlspт (T,,,*.), onе maу ехpeсt a notiсеablе dесrеasе in the NМR signal
intеnsitу in this t.,nр..utui. rеgiоn Fгее е!есtгons aге рaгamagnеtiс paгtiсlеs rlv'hiсh bring
about a fast nuсlеaг щin rеlaхatйn of substanсе at thе suгГaсе' Тhеrеfore an inсгеasе in thе in
thе matегiаl сonduсtir,itу must bе aсcоmрanied bу a NIr{R signal bгooding [13] In viеw ot.
thе fast mоlесulaг
"*"й"ng.,
spесtra displaу an avеrаgеd signal fог adsorbatе molесulеs
.on'iguou' to thе suгfaсе and геmotе Гrom it, Тhс thiсkеr is thе adsoгbеd substanсе layег at
thе iiterfaсе. thе highеr is thе соntгibution to thе mеsurеd signal whiсh is madе bу thosе
molесulеs rvhosе propегtiеs appгоaсh thе adsorbatе bulk pгоpегtiеs, and thе smallег is thе
ехpеrimеntallу measuгеd width оГthе Nlt4R signal,
1. Ехpегimеntal
oispersе powdегs of Voz rvеге prоduсеd by solid-phasе sуnthеsis mеthod [2] Тhе Vzo:
po*а.. ulirahigh puгitу giadе wai usеd as a itaпing matегial' At first, vanadium oхidе V:oз
i'as p."pu,еd tйгoughiь"*аi,..t rеduction rvith hуdrоgеn of high puгity' Voz was synthеsizеc
lrom a sloiсhiomеtгiо miхturе of \''эoз and V:os bу thе rеaсtion:
V2o3 + V2o5 э;|!Q,
NМR spесtra wеrе.еgisterеа with a high-rеsolution spесtromеtеr WP-100 SY (Brukеr'
Gегmanу). ]-еmpеrature*r,vithin thе dеtесtoг ъ,as maintainеd сonstant with thе aid of a thегmal
dеviсe B.VТ-1000 aссuratе to +1 dеgгее' Duгing thе proсеss оf тhе tеmpеraturе sеtting
dеpaгtuгеs from a prеdеtегminеd valuе did not ехсееd 2,5 dеgrееs, Тhе signal intеgгatiоn
u".ul.u"у 1y35 +15 o/o Thedosing of thе ъ,atет adsoгbеd on Voz powdeг samplеs was еffесtеd
with a miсгodosеr by thе injесtiБn of fiхеd poгtiоn of Hlo into a mеasuгing ampoulе to stand
гoi в duys fоr thе ajsorption еquilibгrum tobе еstablishеd Thе watег сontеnt of samplеs was
dеtеrminеd bу mеasurеmеnt of thе 'н NlvlR signal intеnsitу at 293 K
Polуеthуlеnе glусol (Fеrak) with a moйсular mass oГ 15O0 was сhosеn as a polуmег.iс
matriх. тье mjlting tеmpеratuге of this substanсе is 3l5 K, thеrеГoге at tеmpeгaturеs neaг to
iь. pт tеmpегatuгJ fo. Vo, its statе is сlosе to that of a vеry visсous liquid PЕG is ablе tо
absoгb a сonsidегabl" u*ount of rvatег. Bеsidеs, it сan dissolvе manу oгganiо сomp^ounds A
usе was madе of thе сhеmiсal1у purе TЕABr. Thе tеst samplеs wегe pгерared in thе fo-llowing
waу. At room tеmperatuге l Ъu't oг TЕАBг, 10 paгts of PЕG, and 20 рaгts of Voz .n'еге
gй,ndес in u po1."iluin .o.tui, following whiсh thе homоgеnizеd miхturе wаs plaсеd intо а
mеasurеmеnt ampulе and hеatеd in it at a tеmреratuге сlosе to thе boiling tеmpеratuгe of PЕC
foг05_1'0min.
]nс]
nfr
sam
oссt
vaгii
hn.l'
at thr
сasе
tightt
whos,
intегa
238
iеnсе oг an
sОгрtion of
.
as wеll as
: tуpеs of
;r ibг nеw
;.:сklу and
:..i dегs and
:: аdsorbеd
: s'.tbstanсе
:.е pгеsеnсе
r::i may bе
: :hе radiо-
.;iеasеs at
).)lR signal
,.,':l;h bгing
:.: ln thе in
.:l l'iеw of
:-. -:lolесulеs
i-. -. layег at
r-=
.oу
thosе
г. .i]r is thе
]. ]rе V;os
п .'.lе Vzoз
ц . :.:hеsizеd
/\
/\
__/^\
__/N
/ \-'
100 0 -100
2. Rеsults аnd disсussion
Figuге la shows thr tеmpегatuгe dеpеndеnсе
.o.f
thе lH Nlvд. spесtrum foг Voz samplesсontaining 5 % (bу weight) of adsorbеd Hzo. Тhе speсtrum сonsist of a singlе pеak whosеshapе is сlosе to a Gaussian, and whosе width vaгiеЪ fтom 7 u.o i.; T < Тьlspт) to 12 - |4kHz (at T > Тьlspт). Тhе adsoгbеd ]vatеr signal intеnsitу at thеlhasе tгansition dесrеasеsapproхimatеlу bу a faсtoг of 2, whiсh allйs us to makе a ,еiiublе гесord of absoгbingpгopегtiеs vaгiations foг samplеs, Thе сhangеs of thе adsorbеd watег intеnsity withtеmpеraturе in thе intеrval of 200 < T < 250 K аге
shоwn in thе fig. 1b Thе lеvеl of hуdrаtion for samplеs was 4, 5 and 7 Yo wt. of Hzo (сuгvеsl - 3 respесtivеlу
I nte n sty
'.Г"l
,tI
._-=-"'q\-
i{-5ъrюl vvъ;{
l{_1%н2oI
l з-zxq:ol
240 260 280 з00 з20
теmtpeгаtuгe (K)
a)
6 (ppm)
l.Brukеr,
... thегmal
-з sеtting
: еgrаtion
. эffесtеd
r :c Stand
.:.еs was
::iуmеriс
;i nеar to
. ablе to
::unds. A
rllowing
.)2 wеrе
. -.1 into a
... cf PЕG
b)
Fig.1 a) Tеmpeгature-induсеd vaгiations of 'Е{ N},д. spесtra of *aieг adsоrbеd on Vo,
powdегs: (water сonсеntration 5% \Цt.).
b) Теmpегatuге depеndеnсiеs oГthе ,H Nllп. signal intеnsity foг watег absoгbеd
on the Voz powdeгs suгfaсe at diffеrеnt lеvеls оf samplе hуdration.
As it is sееn from this figuгеs, all thе samplеs displaу tеmpеraturе hуstеrеsis whosе loop aгеa
inсгеasеs with thе samplе humidity Тhе onsеi oi мsi'т is shiiiеd to a геgion oi to*
tеmpегatuгеs as it is thе сasе foг polyсгystallinе films of Vo2 [l]. Howеvеr, thе1еmpегatuге
of thе phasе transition onsеt is somewhat lowеr thеn foг thеsе fiims and amount to 31j K for a
samplе сontaining 4 % wt of FI2o (fig. 1b, cuгve 1). The dесгеasе in thе signаl int.n,lty
oссurs in сonсord r,vith thе inсгeasе in its rvidth rvhiсh givеs rеason to infе*г a symbatiс
vaгiation of thе matеrial absoгbing propегtiеs and thе frее iaггiегs сonсеntration at tЬe solid
body-adsoгbed watег intегfaсе'
Тhе mеasuгemеnts wегe madе in thе геgiоn оf high lеvеls of suгГaсе hydгation whеn
at thе iпtегfaсе of dispегse Vo2 paпiсlеs thеге Ь a multiйyеr film of adsoгbеd watеr. In this
сasе onе сan sсhеmatiсallу distinguish bеtwееn tightly and wеakly bond watегs Il4]. Тhe
tightlу bound watег is usually refеггеd to as that paгt of thе ,upЁ.fi"iutlу aаsoгbеа,*aй.
whosе еnегgy of the intеraсtion with the suгfaсе is muсk highег thеn tЬе еnergy of the
intеraсtion bеtwееn molеоulеs in thе bu]k of thе liquid. SuсhЪ wateг doеs пot;; from a
2-3фK
3-3oк
+з{oK
5.- збo к
2З9
liquid statе to a solid phasе of' iсе
.at.
T <2.7з K and frееzеs at signifiсantlу loweг
tеmperatuгеs. Suсh pгopertiеs arе сharaсtеristiс oГ suгfaсе adsoгption films whose thicknеss is
2 - 4 mоlесutar diamеtеis. But if suсh a film has a grеatет thiсknеss, in thе proсess of сooling
a weaklу bond watеr f,ее,е,. As a rеsult, spесtra oT thе high.rеsolution
,н Nпr,д1 bгing out a
dесгеasе in the watеr ,ignui]nt"n'itу sinсе йе solid watег is nоt obsеrvеd in thеsе spесtгa duе
;"-;;;;;iiti.еs (аoin to 10.6 s) of thе transvеrse rеlaхation of nuсlеar spins.
Thе appгoaсh Jеsсгibеd *as takеn bу us to thе idеntifiсation of that tyрr оf watеr
whiсh is rеsponsiblе for thе сhangеs in paramеtегs of the tеmpеratuге hуstегеsis at МSРT in
Vo2. Figurе lb (сuгvеs 1,2) shойs thе tеmpегaturе dеpеndеnсе of.thе watег signal intеnsitу
whеn freеzing su,npt"s, д, i, ,..n from thii figuге, in ih" .o-"" of thе samplе сontaining 4 o%
wt, of watеr thе dесrеasе in thе watег signal intеnsitу is oЬsеrvеd ,оnly
at thе tеmpегaturе
T <24oK, i.е., ti,е'nain amount of watеiis a tightly Ьound watеr. As thе lеvеl of hуdгation
inсrеasеs ю 5 o^wt. th; fтaсtion of thе wеaklу bond watеr inсгеasеs, and its frееzing оссurs at
tеmpеratuге сlosе to 2;i;. ih"', thе еxpегimеrrtal data givе еvidеnсе that it is thе inсгеasе of
thе amount оf weak1у iй *..., ц,hiсh 1eads to an inсrеasе in thе width оf thе tеmpегafurе
hysterеsis loop at MSPT'
Тhе ocсuггеnсе of hуstегеsis phеnomеna in proсеssеs proсeеding at first-ordет phasе
traпsitions is attгibutеJtothе е*istеnсЪ of tье."u'ung"n1.nt activation еnегgу fог a substanсе
(solid adsorbеnt in oui сasе) at a phasе tгansition and"shouid not dеpеnd on thе availabilitу of
adsorbеd watеr motесut., ii,tani from thе ,u.Гu." Thе rеgularitу disсovегеd sееms to bе
сausеd by thе faсt that dispегsе paпiс1еs oi vo, arе сoйplех.aggrеgatеs (foгmеd from
pгimary miсroсrystals ;; ;h; proсЁss оf thе sуnthеsis] *l:'i::.{iсе has a high affinitу to
watеrmolесules,Тhеwatегреnrtratingintоgapsbеt*еenmiсroсrystul',"**:1^::1*il*
;;;;;;.Ь iвl unJ,1ь.'"ьу, variеs thе lrЬpепiеs of dispе.rsе oaпiсlеs weaсеnlng tnе
bonding bеtъ,ееn,n"* ii'ьinoеrs a сoordinui.l.,-Ьungеmеnt of ехtЬndеd matегial domains
at МsPT' and, as a сonsеquеnсе, thе еnеrgу whiсh is n"i.''u'y lor a phase tгansition to oссur
'n",.u,"}n" validitу of thе hуpothеsis about thе mесhanism dеsсribеd is substantiated by thе
faсt that thе introduсt;;;i,\io, powdеrs lnio-* uqu"ous mеdium lеads to thеir dispersion
and foгmation of stablе suspеnsions \vьo*..Ъur.i.й :i: i., bl :
- 2 oгdегs of magnitudе
smallеr thеn in tье сasе-oi staпing powdеrs sЪlid paгtiсtеs in suсh suspensions do not sеttle
out in thе сoursr oг,.uЬ*r аays, йьiсh сor,еsponds to рarticlе sizеs smallеr thеn 0.1 mm.
Thе tеmpеraturе dереndеnсiеs-of thе ii]-l'ГI',ш. signa1 intеnsitу in suspеnsions diffег in
manу rеspесts fгom ti. й"t"а pоwdегs dеsсгibеd abovе. Figurе 2 disp1aуs thе trmperaturе.
induсеd vaгiations of N\,IR spесtra unа *ut.. ,ignal intеnsitу й watег suspеnsions of Voz.
Wе invеstigatеa suspensЪ;;il'; solid phasе сonсеntratiоn wеre 60 % wt. (Fig. 2a, b'
сuгvе 2) and 7 oh*' iii;.;;, сun,е 1). г,й iь. ju*taposition o| thе data in Fig. l and Fig. 2
it follows that the
'J.oъ;;i;;.;.i
oгьtspт in watег suspеnsions is bгoadеr thеn tn
hуdratеd powdеrs. ThЪ transition onsеt is obsегvеd at a tеmDегaturе сlosе to гoоm
tеmpеratuге.Thеthеrmalhystеrеsistoopu."а-."..u,.,,andinthесasеofdilutеsolutions
hеaiing сuгvеs display a nеgative hуsteгеsЬi iь. Ji'tin.t;on in the propегtiеs of hydгatеd
powdеrs and suspеnsiЬns of Voz maу be attгibutеd both to сhangе of thе substanсе gra1n slzе
distribution and to;;;Ь;;. oгiь. iispе.,iu.-..аiu* ll ",9..^..l.
make a сhoiоe bеtwееn
thosе faсtoгs *,. rooк"J}Ь, a liquid whiсh whеn miхеd with watеr in anу rvould not сausе thе
dispеrsion of Voz po*o.,, onЪ of ,u.ь п].jiu tu.n.а oш to bе dimеthvlsulfoхidе (DMSO)
Figurе 3 illustratеs i..p.*u,. "ч'1t]:i
oi й ,r'up. oГ NN{R ,р".t.u and thе intеnsity oi
signals гo, u,u,p.n,й;;iЬ, in DМSo (fi;.];,;;;.2) and in a miхturе of Hzo + DМso
iйье t : 1 pгopoгtion (fig 3b' сuгvе 1).
:
s
.i
п
С
I,
ai
SL
rhr
пl(
ijо
On
r L.-
L Llс
.l .-usl
i tl(t ^,8
n10
'. .t
i25
рou
аbrэ.
аttгi
1гее
рara
molс
thр.
240
-7\=-.ч
-/\ --'i
--/
^
\,-д
-_--_--.t- '
ut\
:.i lowег
:::knеss is
. j - lо]ino
. .: .эu: a
, ----^;,.---:-. : u*a
i ,___/ .t____l_-]
2ф 1ф о .1Ф .m
5 (pрij
I
г
lllЕ
l, ii
шlll.
Fг"
]пLl,
Е
a) Ь\
Fig. 2. a) Тempегaturе u1lutlo'n:9.f 'FI ]rltv{R speсtrum ,ьup. гJl watег in 60 wt уoaquеous suspеnsions of Voz; b) Еffесt of tеmpeгatur. on 'Fi N]й ;;;;;;ignal intensityfor watеr сonсentration'
Тhе сonсentration ofthе solid phasе w,as about
80 % wt'' whiсh сoггеsponds to sеttlеd
suspеnslons, Thе speсtra ргеsеnt the ovегall
signal of proton of rvatеr and DМso
moleсulеs'
Comparing thе data offigs, 2b (сurve 1) and 3b
(сuгvеs l,2) makеs it possiblе to сonсludе that
thе shapеs of tеmpеraturе dependеnсiеs |oг a
dilutе \\'atег susреnsion and сonсеntгatеd
suspеnsions of Vo2 in DМSo and its miхturе
with wateг are pгaсtiсally idеntiсal' Thus, the
еxperimental datе сoггoboгatе thе сonсlusion
that in this сase thе dispeгsivе mеdium ехеrts a
moге profound effесt on сharaсtегistiсs of
МSPT in Vo2 than the сhange of its dispегsitv
doеs.
onе of thе distinсtivе fеatuгe of suspеnsions onthе basis of DМSo is a i.*p.,atu..
dеpеndenсe oГ a line shaре in N\4R spесtra
(fig зa) Ц'hile thе signal intеnsiry dесiеasеs
mоnotonously thе signal width makеs a гapid
leap at tempегatuгеs in a гansе of
325 <T < 3з0) K as it is thе сasе in hidratеd
powdeгs (fig la) As it has beеn mеntionеd
above, an inсгеase in thе line width in 'н N}4R
spесtгa in thе геgion of tv{SPТ for Vo2 is
attгibutеd to an inсгеasе in thе сonсеntгation of
frее еlесtrons in thе solid givе гisе to a
paramagnеtiс relaхation of nuсIear spin of H2o
molесulеs сontiguous to thе Voz suгfaсе. At
thе same timе thе signal intеnsity dеcrеasе is
Fig 3..a) Tеmрranге vаriations of 'гl }\rlъд. speсtrum
:Чry fo,. чg.ragе signаJ of iуatеr алd dimеtlrylsulfoхiaе
iп 80 rи. % Vo2 susреnstons сoпиiniлg s% *t' oг н,o'
b) Еffесt of tenlpегaturе on 'н Nlvfi'
-signаl
lnlепsttiеs for suspеnsions of Vo2 u'hosе liqшd pйasе
сontarns 95 Уo*t. DМso (1) aлd,S}oАoмso ()l' aлa ше
соnсеntration ofthе solid phаsе in 80% wt.
L
.Ч*'*.
ъ;-ч"*
tli
211
dеtегn-linеd by thе inсrеаsе оl thе absoгbing сaрaсitу of thе rvhоlе sапiрlе l.oiumе. Тhеn thе
obsегv.еd unсооrdinatеJ.'.'i,tion, оf thе sцnaiilltеnsitу and width..maу bе attтibutеd to thе
diffеrеnсе in thе P.l.tеrn|сrat.r,е оrr t|iе pЪгiphегy u"i i1-tь1 1:': "'\ro2
paпiсlеs' Thе
еxistеnсе оf a nеgativе tеmpегatilrе hуstrгеSls in sus!"n,ions givеs геаson to bеliеvе that thе
mесhanisпl of tье сrspе,si,.е пlеdiuпi еffесt on МsPТ рaгamеtеrs is a гathег and rеquirеs
fuпhеr
il,!o'i',,'u,,.utеs thе tеmpегаtuге.induсеd vaгiations of thе lН N.Ъ4R spесtra for Voz in
PЕG as wеll as th. t.й;;;;;;Ъ.p.no.n.. оf thе proton signal intеnsitу (1).
Fiя. 4. Tеmpеraturе-induсеd .,,аriations of thе ]H NМR spесtгa shapе and signal intеnsitу for
. -о.
orotЬns in Voz powcегs in a PЕG matrlх.
In thesе spесtra thеrе is a broad singlе pеak that
сн anJoн g,oup' of PЕG and of imрuritу wаtег
й"r""'r.' aйoгbеd on thе Vor suгГaсе and in thе
Б'l[
"г
РЕG As the tеmpeгaturе aррroaсhеs thе
гi^.,.rnр".u'urе valuе, thе width ot. thе signal
,ьЪ'olo.in...u,.,, and its intеnsity dесrеasеs bу
il;;,.,
';'
*ьi.ь utlo..us геliablе rесoгdings оf
thе PT ocсuггеncе in thе sуstеm' Th: РТ
p,u'o.,' for a Voe powdег in a PЕG matriх aге
сlosе to thе paramеtегs that еaт1iег wеrе obs.егvеd
in hvdratеd.Voz рowdегs in thе сasе оf lоrv
соnсЪntrations of adsoгbеd rr.atег,
At tеmpегaturеs Т<з05К thе
rеlatiоnship I __ f(T) сiйr.y' a dесrеаsе in thе 'H
i.'nк 'le'ы
iйnsi1v. -n]:n 'i#,'o"f| '"'n3
paпiai сrystailizatiоn ol rЕ\J, ^L
сrystallizatron tеmpегaтurе thе polуmеr рoгtlоn
is an avегagеd signal for protons оi
Fis. 5. Tеmрегature dеpеndеnсс
oГ.r'агiotioni оf thе t11 ;rMR
sisnal intеnsitу for a samplе оt
VЪ, in a PЕG тnеdiurn
сontaining 10 r,r't %o of lvatег'
Fr€quыtсy K}tz
:]с Thеn thе
l5Lltеd to thе
дliс1еs, Тhе
jе'..е that thе
and rеquiгеs
:a tbr VOz in
that doеs not intеraсt with thе suгfaсе ftulk сomponеnt) solidifiеs and is not rеsisteгed anv
moге in thе sресtra duе to a сonsidегablу lorvег timе оf tгansvегsе геlaхation oi pгotons in
solids in сompaгison with that in liqurds, T.hе spесtra registеr only the PЕG molесulеs whosе
fтее еnеrgу has bееn lowеrеd by thе adsorption intегaсtions with thе surfaсе. Suсh molесulеs
сan pass into thе solid phasе of PЕG only at a tеmреratuге that is lowег than the tеmpеratuгe
of сrystallization of PЕG in thе bulk of thе liquid. Тhе stгongеr aге the adsoгption
intеraсtions, thе lowеr arе thе tеmpеratuгеs at whiсh thе стystallizatiоn of a substanсе is
possible
The paгamеtегs of МSPТ in dispегse Vo2 ma} substantially vaгy whеn thе moistuге
сontеnt of a samplе inсгеasеs, on thе onе hand' this variatiоn is сausеd by thе fоrmation of an
еlеctгiс сhaгgе on thе suгfaсе, whiсh is induсed Ьy thе еlесtгon dеnsity tгansГег fгom Voz to
unshaгеd еlесtron pairs of oхygеn atoms of adsorbеd watег molесulеs,la and' on thе othег
hand, it is duе to сhangеs in thе intегaсtions bеtwееn miсгoсгуstals (whiсh foгm Voz
paгtiсlеs) owing to wеdging pгеssurе of adsorbеd watег'
Fig. 5 shows thе tеmpегature dеpеndеnсе of thе ,H N]rД. signal intensitу foг Vo2 in a
PЕG matгiх whosе watег соntеnt is l0 wt% A сomparison bеtwееn thе data of Figs. 5 and
lb pеrmits us to infег that, in сontrast to thе сasе of hydratеd Vo2 powdеrs, thе tеmpеratuге of
МsPТ in a PЕG mеdium vаry slightly, whеn thе moistuге сontеnt of a samplе inсгеasеs. It is
attгibutеd to thе faсt that molесulеs of PЕG intегaсt with molесulеs of watег thгoush
formation of hydrogеn-bondеd assoсiatеs- As thеy pеnetгatе into thе bulk of thе polymJг'
moleсulеs of water do not adsorb оn thе Vo: Paгtiсlе suгfaсе but геsidе within thе polvmeгiс
matriх'
in the сapaсity of a modifуing dopant сapablе of ехепing an effесt on thе Voz suгГaсе
wе havе tеstеd a quateгnaгy ammcnium salt TЕAI}г, Somе mеdia with a 1ow diеlесtгiс
pегmitivitу, whiсh inсludе polуеthylеne gli,сol' сan carтy quatегnary ammonium salts in thе
fогm оf tight ioniс pairs. Bесausе of thе grеat diffеrеnсе in sizеs of anioniс and сatiоniс
сomponеnts of a moleсulе thеiг mobilitiеs diffег considегably. In thе visсous PЕG mеdium
this diffегеnсе should bе еvеn gгеatег on aссount ofthе stгong dispегsion intегaсtion betwееn
еthуl gгoups of thе (С2H5)аN- сation and molесulеs of thе polymег. In viеw of this, it сould bе
ехpeсted that сationiс and anioniс сomponents of ТЕABr molесulеs would intегaсt with thе
Vo2 suгfaсе in diffегеnt ways and givе гisе to its polari,zation'
Fig. 6 disрlays tеmpеratuге variations of thе ,Н NМR spесtra for Vo2 in thе PЕG
mеdium сontaininq small (< 1 wt %) additivеs of TЕABг,
I
!
I
i
з t.lr lgi
' -1
r:f0
I"1
I.,,' -.1
I
I
,..]
i
ffiso
r- .ltеnsitу for
:.. '-..rotоns of
: эndепсе
:{ NMR
-:nplе of
;nеdium
:i et.
heаtlпg
*''- gвб к
'.>:.^.-^....i99 5.->{.;дF'б к...'"..-.a6o к
./f
-*-,t'.rf/
*"*-'"/ /
s4о к
к
***Jё к
Од6 к
trequФgy кю
сoolltlg
1,
s16
к
46к
к
Frcqu-o}. кA'з
h
Е
hr Fig. б. Теmperatuге-induсеd vaгiatiоns of thе 'H }IMR spеctra shapе foг а samplе of Voz
in a PЕG matriх сontainins an additivе of tеtгaеthvlammonium brоmidе
:чЭ
Asisеvidеntfгomthеfigurе,athеatingupto,tеmpегatuгеslowerthаntheIr{SРTtеmpегaturе
'Jt'J;nfl Н;#ilf.,:::жу}'l::'..ffil;*ж*нi,'i:''?'1ffж}"Ж':iH:
siяnal u,idth unа to\v",in! "i
ii,-i"Ё",i,у
'
нt thе samе timе, howеvеr. in thе baсkground of
thЪ main signal thеге .p;e;; a signa! oг u rooo,^iniJ*;y ;;* width is substantiallу smallеr
;;; ;й ;, Ьf th е *a io'.'.-:+ jъt ;Цi
;i;Н" ;Эi,i
"
jж:"
J"'!:: ff;lr' il:Ж" i: ;цi
trmpеratuге intегval
',19:,'...,,":".l'"-].'J,lТ'.;;;;"";;;"rе distinсtlу undег cooling of
;;;;ъ;"; of thе sесond;'j::::lJ''Тffilf,,'n...,o"".,u is not dеtесtеd onlyЪt tеmpеraturеs of
a samplе In this сasе t
T<310K
Thesamplеsundеrinvеstigationсо^ntainsnоtоnlуmolесulеsofPЕGbutalso
molесulеs of ТЕABr i'p.o ro *tй;, tь.,.гo,..iй..,".onа signal оan bе attгibutеd both to
:''"$ь"iH'il"'ii","", оf dissоlvеd Т!нBг Sinсe suсh " '^Tfj."J* $Т:i'::-'J;
hоmоgenization in ttrе"Jiju^i.' ii is p-ossib.lе to assumе that during l
lff :I*:;:}*;:
j*d*Jl*Т:tgЁr#;*;:::;**Ц{j"**=::".:t[T
rvith inсгеasrng tempегatuте thе intеnsitу of thе sесond сomponсnt
additional dissotutlon oiiвдво' ivhiсh-dоеs ""' "й..
*nh tйе data P"гФ."}il:
u6,ignul
Тhеn, it is most riк.io]iйiь. uЬ*ег"еd narтow signal (as rvеll as th
frоm рrotons of PЕG .oi..ur.,, ьu, ,i,. p,o'fr;i;;.;.;..surfaсе of nеaгbу Vou paгtiоlеs
с]iffr:г from thosе tnat ,дivе гisе to t.hе bгoad signal сompоnеnt
t-f,) 'f:,; жТЕ ::?,ff.':"l !:Н$j I
additii'е' In сompaтtsо"'''iiй irlJ dеpendеnсе 'u,Г
:'f*:}'i::' i'у;n:ril'ff:T''-'#:';l,. г
[ffi:".# LiK""l."l.,:?ТlT' 'i: 1J:;
.,|
#"i#1*";:;"il"s,'tinry':*,q "
I
l;:.{:.':ilLтТн,:l';rЦjj:h;i,*j,,|'
]
maximum valuе (Fig. 6) :-+^.*.дtдrl Ч,ffi'u^''''tn.'?.*ii,.?.ьi."еd сan bе intеrpгеtеd rвs Зie Jlv
as follоrvs. In thе сasе #juй': ioz роwdеrs Tenpеratuгe, Х
н*h:*.т.J:,*: 'ж,,i: ТЫ";#i;: .,*. 7. Tеmpеraturе depenrtе":i g
,"'#, *ь.гe thе МSPltеmpегatuтr,i::1'"Р:lo variations of thе ,н Ntn,fil
into a highеr tеmреraturе геgiоn "]'l]::l::: signa1 intensitу for a powdег
zonеs thе rn.tul-,"*l"onJu.tБ. ph^:" T1l:,:l:" ЬТvo' in a PЕG matrix with
ь;ъ';;.J;ntу wьеn thе tеmpегaturе геaсhеs an additivе of TЕAЕ}r,
,"н"
"'l,".-
oг
"т=зos K Thе рhеnomеnon
dеtесtеd is thе flrst ехamplе оf the inсrеasе^in
iiJ;i $jT,--i"Тi'H:
"Тj.1
J:ж. :ff : *Т
TiхЪ..,l:, i; m: М l|] t е mр егat u r e. m a'У b.
еmrrgsl1се oгun "l".t,i,j';.;;;;;;;;;"Iт^":;#i:;й""Jto
pota'i,ation of molесulеs о:
an adsorbеd substanсе. In paгtiсulaт,..,",'*...с';;й;; of elеЁtron.donating molесuiеs о:
ammоnia and watеr tь" ?o, suгГaсе u.q"i,",-u Jositiu. сьa,g" whosе valuе inсrеasс.
211
р еraturе
rе thit at
ls of thе
гЬund of
v smallеr
., in thе
sеs. Thе
оoling of
:atuгеs of
but also
:j both tо
ээaгеd by
lеlting of
: manifеst
еr.реоt that
sе (duе to
'i . А
i a signal
); paгtiсlеs
:еnсе of
ri NМR
з powdеr
::гiх with
:a:urе maу bе
..: molесulеs of
:: molесulеs оГ
''-з,uе inсrеasеs
propoгtionallу with сonсеntratiоn of adsoгbed substanсеs, Foг thе matеrial in quеstion, i.e thеsystrm of dispегsе Voz in a PЕG matгiх with additivеs of ТЕABг, onе саn е)Фесt thеaрpеaranсе of сhaгgеs of oppositе signs on thе Vo: paпiсle suгfaсе. Aсtually, nфut;u"i|сhargеd ions of bгominе aтe a morе mobi1е typе of ions' Thеsе ions сan diffusе to thе Vozsuгfaсе. In this сasе, nеaг thе suгfaсе onе сan obs.*. thе еmегgеncе oiеIе.tн" fiеlds bеtwееnnеgativеly сhaгgеd Voz..partiс^les and (C2H5)aNt сations that aiе loсatеd within the polymегiс
matriх. Sinсr thе solubility of TЕAIIг in PЕG is low, tetraеthylammonium ions aге loсatedonlу nеaг a small zonе of the suгfaсe oГ Voz paпiсlеs, whiсh aссounts fbr simultanеous
eхistеnсe of thе sеmiсonduсting and mеtalliс phu'.' of \ro2 in a widе tеmpегatuгe rеgion(]40 - 365 K) It should bе nоtеd that in this tеmpеraturе intегval thе width of thе sесond
-sЦnal
is сonsidеrablу smallеr than that of thе first onе' So far as the signal width in tье iriNМR speсtra inсгеasеs with inсгеasin8 сonсentгations of frее еlесtrons, the smallег width ofthe signal of polyеthуlene glyсol molесulеs adsoгbеd on thе Vo2 suгfacе may be artгibutеd todесrеasing in сonduсtivity of thе Voz suгГaсе zonеs геsponsiblе foг thе appeaгanсе of thissignal.
In сasеs whеге thе^ pгopоsеd appгoaсh is .,'alid, it is possiblе to ехpесt that a timе
dеpеndеnсe -will appеaг for thе ratio of сonсеntrations оf Voz poгtions whiсh have asеmiсonduсting oг mеtalliс phasе. This dеpеndenсе is assignеа to tйе faсt that, as bгominеions undегgo геduсtion. and сhеmisoгption on thе Vol/pЁG intеrfaсе, nеw molесulеs ofTЕABг (that is pгеsеnt in еxсеss) may еntеr thе volumе oссupiеd by PЕG In this сasе, onе
should ехpесt an inсгеasе in thе intеnsity of signals that arе сausеd Ъу thе substanсе loсatеd
nеar the suгfaсe of Vo2 paгtiсIеs with sеmiсonduсting pгopегtiеs'
Thе phasе hеtеrogеnеity oГ dispеrsе Voz in a PЕG matгiх dесreases sharply, whеnPЕG absorbs a small amount of watег' Thus' absoгption of 5 wt,% of watег by thе polymеriс
matгiх lеads to thе pгaсiсally сomplеtе disappеaгanсе оГ thе naггow signal сЬ.ponеnt(Fig 8)
\
\
\
__J
i; {0в
ba
,..
y',,, "* *.'
"
--.н..|
| nc
..,А.ir''' ^
,''.
о7o Х
о4o к
к
оto K
2эo к
Fr€qug,|су к}t
Fig. 8. Tеmpеraturе-induсеd variations of thе lH NМR spесtгa (а) and signal intеnsity
(b) foг a samplе of Vo2 in a PЕG matriх dopеd with TЕABг and сontaining 5 w|.уo of
watег,
Z+э
Suсh a ч.h,1uio^u^.,.:l:Y.,lТ:,t'х",'"1:i;y;H::.-iН:J::'}Т"l",i:.ff."i'':1;fJ-".f;
сations in the polуmеrt
еleсtriс fiеld that."i,t, ь.i*..n thе TЕABI.;;;;;,;;;".gatiuыу сharsеd surfaсе of Voz
оartiсlеs thеse сations *;;;';;;;; tь" ,u,ru.J. ii'" й.ы..iЕ"'riс fiеld isЪonfinеd within thе
lap bеtwееn tье твдвiс;i;;;;;а vo, puпit..'u,ru.., and in tегms of its geometry it is
in.utogou,*-.,ч1,;i:*J.::-':1rl**":*:g'тlу+ьтн:':i:ixъж#i:'".l''Т
of thе сations towaгсls .
:' ;й;;';;;ъ ih" aсtion of thе loсal еlесtгiс fields.
i;"?"l'?T3ll,?, ",
this studу it. is possiblе* j:::у*jН: l:..rthod
of thе lH NN,к
sDeсtrosсopy oг uа,oй-.oi."ut". Ьuу ь. "й.j.*rу
appliеd. to rе.sеarсhеs into pесuliaritу
oг tь. мspт dуnamiсs in solvatеs .1g *,111,i"ns In thе сasе of hуdratеd powdеrs of Voz
thе mеtal- ,.*i.ondu.iol й. t,un,ition'rеgion is in a tеmрегatuге ranqе of 315 < T < 340 K
and dереnds on the ;;Ё.;;;J;atlon tейi..ть" t.'р",uturе .intеn-sitу
сurvеs displaу a
й*"lь-.ь:тжh[i::iЁ;"д;ж*у':l*:ж'Ц}:l'ж:'J};'Yu.!iЦi::
owing to thе pеnеtratt
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variеs сontinuou,lу. ln..u,^.,.'р.**,. inй"i^-zgs.т.зцЪ к; bеsidеs, a nеgatlvе
i"rnp".u.u.. hуstеresis is obsегr,еd, , PЕG matriх сan ехегt a strong еffесt on, thе
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hеtеrogеnеitу oг vo,, *Ьiсh manifЪsts i.,"'г^i"i.,.-й tьat witьiь" on'.t of МSPT with
inсrеasing t"'p..u.ui. ;;;;i;;;i,h" *;,;;;;p.,,., . thе mеtal,iс statе' and thе othеr
rеmains in tь" ,..i"'o..йul;;g;r19 1l. };;;фlI' "li''^1lo':J,::'.#"il:" :ъ1.}::
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сations loсalized
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matгiх to thе Voz paгtiсlе surfaсе
Rеfеrenсes
1.A,A-Bugaеv,D,P,ZakharchеnУa,.FA.Сhudnоvskу,AМеtal-SеmiсonduсtorPhasе
Тransition."o 'i'
дррri..i1чi ц."1a.
Lеningrad, ','?, ^^-^.n propегtiеs of сompositе
2.
}i.Y;*i i';":'* у'"Щ?ill'Ё, J#:':':.l'ff .:J\iFё,'. iБ ",ё".o'"l
^
an<l
(Pb*Bi r.*)zCa,,Y,i',Б, )i Бili'*l.l-.fiil nй;l;е. _ 1 99 1 - No. l l . _ P. 5 5-58.
з.PP.Gorbik,r-v.Б'Ь.J"in.v]|vak.r",Ъ.а".""nandjnvеstisationofsomеPropеrtlеs
of thin г,tms сompositеs of A:B: ь"oЁ""ip".po*., in rш ,p".i** range llDokl. Akad
4. fl*yr;tl*'# ;i";1*i]fi::sitions -(Еds l,; ^o*"n,,
с P. Poolе, and
H.A. Faraсh)' д".ilй'. '*,,,I.'*Jj;,
s"; Fianсisсo, London' l979.
5.Livagе,.ooii"i""JЪй.i.ыp."p.-Т"'."i-i1ry9'11",oхidеsSуnthеsizеdfrom
Alkoxidеs iz с"",il""iЪn Chеm .к*
]is99. jy^l?]^lT
;''"i:].ili. Dioxidе ,Film
6'
5;ffiT;":"*;,,',#{ Ёj'xl1,l';Ёxi''''Jil
liТ J; Ё".Ы й " And S o l aг
Cеlls 1999 -v')/'_r LЧL-L2'
t0
1l
l1
I2
J
246
r ofTЕABr
lГ thе stгong
faсе of Voz
эс within thе
еomеtry it is
:е migration
l pогtion that
,:.е 'н Nlv[R
1.. рgсuliaritу
" ]еrs of Voz
..Т < 340 K
:s displaу a
i:..'' lt oссuгs
J..1g dispeгsе
:. ..f powdегs
: s'l spensions
: nrgativе
ш. .: ]г Phasе
i ]. :omposltе
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: ] :S
ш:: . эгopегtiеs
l.--.kl.Akad.
i : lоlе, and
zеd from
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.,nd Solar
l0
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\2
Kisеlеv V F', Kгykоr,o V'- Adsoгption Pгoсеss in Sеmiсonduсtoг and Diеleсtriс Suгfaсеs,Springеr Sег. In Сhеmiсal Phys Bегlin-Heidеlbегg N.Y.: spгin!е.-vе.Iag. * 198б -?RS N
Kisеlеv VF, Kozlov KN, Lеvshin NL, Smiгnov NI' Rulling iп Phasе Tгansition ofМеtal- Sеmiсonduсto.':|ilT: оf Voz bу Adsoгption Aсtion7u sotio Statе Physiсs -1988 - V. 30, N3. _P 924-926
P.A. Vozny' P P Gorbik, V v Lеvandovsky, V' Nagoгny, V,М. ogеnko' L.K,Yanсhеvsky Study oГ phasе tгansition paгamеtегs in сomponеnts of thеpolyсhloгotгifluoгethylеnе - vandium dioхidе systеm // Funсtional Мatегials' _ l995, -V2, No i -P 160-163
P A Vozny, P.P GoгЬik, V V Dуаkin, V.V Lеvandovskу, V'М. ogеnko, o o. ChuikоPгoduсtion and сегtain. pгopегtiеs оf polymегiс .o'poiit", of vlnadium fluoгoplast
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Tuгov V V., Goгbik P P, Laguta I'V', еt al. Appliсation of thе Hl NМR-spесtгosсopy
tесhniquе foг thе studiеs of a mеtal.sеmiсonduсtoг phasе tгansition dynamiсs.in hydratЬi
powdегs and Vo2 suspеnsions // Khim. Fiz' - 1996. v ts' No 12. _Ё loo.tos.
Influеnсе of Tеtгaethylammoniub Bгomidе on Phasе Inhomogеnity of Dispегsе
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Tuгov V.V., Lеboda R. Appliсation of H-l NМR speсtгosсopу method foг dеtегmination
ofсharaсtегistiсs ofthin layеrs ofwatег adsoгbеd on thе suгГaсe ofdispегsеd and poгous
adsorbеnts /l Аdу' Сolloid InteгГaсе - 1999. . v ,7g' N2-з. _ P' |7з-2|l
1J
I4
)А1
|
| id | oai:ojs.pkp.sfu.ca:article-63 |
| institution | Surface |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2025-09-24T17:44:40Z |
| publishDate | 2001 |
| publisher | Chuiko Institute of Surface Chemistry National Academy of Sciences of Ukraine |
| record_format | ojs |
| resource_txt_mv | surfacezbircomua/8c/ae58b862c3de8d6e88c05a7e8c3aa18c.pdf |
| spelling | oai:ojs.pkp.sfu.ca:article-632018-11-27T09:42:39Z Metal-semiconductor phase transition in hydrated powders of VO2 as influenced by adsorbed water, polyethylene glycol medium, and tetraethylammonium bromide additives Metal-semiconductor phase transition in hydrated powders of VO2 as influenced by adsorbed water, polyethylene glycol medium, and tetraethylammonium bromide additives Metal-semiconductor phase transition in hydrated powders of VO2 as influenced by adsorbed water, polyethylene glycol medium, and tetraethylammonium bromide additives Turov, V. V. Gorbik, P. P. Laguta, I. V. Shulga, O. V. Semchuk, O. Yu. Grechko, L. G. Ogenko, V. M. Chuiko, A. A. Willander, M. Karlsteen, M. The opportunity of use of a 1H NMR method for study of the performances of phase transition the metal - semiconductor in crystalline VO2 is considered. The influence of the adsorbed water, polyethylene glycol medium and presence of the tetraethylammonium bromide additives on the phase transition performances is explored. The phenomenon of phase heterogeneity VO2 is revealed which is exhibited as simultaneous existence of semiconductor and metal phases. Presumably this kind of heterogeneity is stipulated by an adsorption of bromide ions on a surface of particles VO2. The opportunity of use of a 1H NMR method for study of the performances of phase transition the metal - semiconductor in crystalline VO2 is considered. The influence of the adsorbed water, polyethylene glycol medium and presence of the tetraethylammonium bromide additives on the phase transition performances is explored. The phenomenon of phase heterogeneity VO2 is revealed which is exhibited as simultaneous existence of semiconductor and metal phases. Presumably this kind of heterogeneity is stipulated by an adsorption of bromide ions on a surface of particles VO2. The opportunity of use of a 1H NMR method for study of the performances of phase transition the metal - semiconductor in crystalline VO2 is considered. The influence of the adsorbed water, polyethylene glycol medium and presence of the tetraethylammonium bromide additives on the phase transition performances is explored. The phenomenon of phase heterogeneity VO2 is revealed which is exhibited as simultaneous existence of semiconductor and metal phases. Presumably this kind of heterogeneity is stipulated by an adsorption of bromide ions on a surface of particles VO2. Chuiko Institute of Surface Chemistry National Academy of Sciences of Ukraine 2001-06-10 Article Article application/pdf https://surfacezbir.com.ua/index.php/surface/article/view/63 Surface; No. 4-6 (2001): Chemistry, Physics and Technology of Surface; 237-247 Поверхность; № 4-6 (2001): Химия, физика и технология поверхности; 237-247 Поверхня; № 4-6 (2001): Хімія, фізика та технологія поверхні; 237-247 3154-8091 3154-8083 en https://surfacezbir.com.ua/index.php/surface/article/view/63/62 Авторське право (c) 2001 V.V. Turov, P.P. Gorbik, I.V. Laguta, O.V. Shulga, O.Yu. Semchuk, L.G. Grechko, V.M. Ogenko, A.A. Chuiko, M. Willander, M. Karlsteen |
| spellingShingle | Turov, V. V. Gorbik, P. P. Laguta, I. V. Shulga, O. V. Semchuk, O. Yu. Grechko, L. G. Ogenko, V. M. Chuiko, A. A. Willander, M. Karlsteen, M. Metal-semiconductor phase transition in hydrated powders of VO2 as influenced by adsorbed water, polyethylene glycol medium, and tetraethylammonium bromide additives |
| title | Metal-semiconductor phase transition in hydrated powders of VO2 as influenced by adsorbed water, polyethylene glycol medium, and tetraethylammonium bromide additives |
| title_alt | Metal-semiconductor phase transition in hydrated powders of VO2 as influenced by adsorbed water, polyethylene glycol medium, and tetraethylammonium bromide additives Metal-semiconductor phase transition in hydrated powders of VO2 as influenced by adsorbed water, polyethylene glycol medium, and tetraethylammonium bromide additives |
| title_full | Metal-semiconductor phase transition in hydrated powders of VO2 as influenced by adsorbed water, polyethylene glycol medium, and tetraethylammonium bromide additives |
| title_fullStr | Metal-semiconductor phase transition in hydrated powders of VO2 as influenced by adsorbed water, polyethylene glycol medium, and tetraethylammonium bromide additives |
| title_full_unstemmed | Metal-semiconductor phase transition in hydrated powders of VO2 as influenced by adsorbed water, polyethylene glycol medium, and tetraethylammonium bromide additives |
| title_short | Metal-semiconductor phase transition in hydrated powders of VO2 as influenced by adsorbed water, polyethylene glycol medium, and tetraethylammonium bromide additives |
| title_sort | metal-semiconductor phase transition in hydrated powders of vo2 as influenced by adsorbed water, polyethylene glycol medium, and tetraethylammonium bromide additives |
| url | https://surfacezbir.com.ua/index.php/surface/article/view/63 |
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