Trong bii bao niy chdng tdi khio sat cic ye'u td anh hudng tdi q u i trinh hinh thinh hat NiO cd kich thudc nanomet dugc diiu che bing qua trinh tu bdc chiy gel polyvinyl aneol.. Phu[r]
Trang 1Tgp chi Hoa hgc, T 47 (3), Tr 333 - 337, 2009
KHAO SAT CAC YEU TO ANH HUONG DEN KICH THUdC HAT CUA OXIT NIKEN DUOC DIEU CHE BANG QUA TRINH TU
BOC CHAY GEL
De'n Tod sogn 23-6-2008
LUU MINH DAI, D A O NGOC NHIEM, VU THE NINH, PHAM NGOC CHUC
Vien Khoa hgc Vdt vieu - Vien Khoa hgc vd Cdng nghe Viet Nam
ABSTRACT
Nickel oxide with tiny particle sizes is formed by auto combustion process of nickel nitrates and polyvinyl alcohol (PVA) gel Factors affecting on particle sizes of nickel oxide including pH and temperature of gel formation, mole ratio of concentration of nickel and the concentration of polyvinyl alcohol used to produce gel were examined The particle size distribution of nickel oxide was measured by particles analyzer The powders morphology was observed by Transmission Electron Microscopy (TEM)
I - MO D A U
Niken va cac hgp chit cua niken da dugc
nghien cdu, dng dung vio rat nhiiu cac nghanh
nhu luyen kim, vat lieu td, bgt mau, hda hgc xuc
t i c [3 - 5, 7, 8] Cho de'n ngay nay cang dugc
quan tam do c i c tinh nang dac biet cua chdng
Gin day vdi viec phat triin khdng ngdng cua
cae loai vat lieu mdi nhu vat lieu cd kfeh thudc
nanomet dang dugc nghien cdu rit manh me, ed
nhiiu cdng trinh cdng bd vi chdng Trong cdng
trinh trudc day chung tdi da nghien cdu ve anh
hudng cua nhiet do nung de'n su tao thinh pha
cua NiO tha'y ring d i thu dugc NiO don pha
phai nung m i u d 600"C trong 2h, nhiet do tao
gel 80°C, ty le mol Ni/PVA = 1/3, pH tao gel la
4 Trong bii bao niy chdng tdi khio sat cic ye'u
td anh hudng tdi q u i trinh hinh thinh hat NiO
cd kich thudc nanomet dugc diiu che bing qua
trinh tu bdc chiy gel polyvinyl aneol Phuang
phip niy da dugc chdng tdi nghien cdu de diiu
che thanh cdng mgt sd oxit dat hie'm, vat lieu
chda oxit dat hie'm cd kfeh thudc nanomet [1, 2]
II - THUC NGHIEM
\ Hoa chat
Dung dich mudi niken nitrat ed do saeh 99,9% (PA).'
Polyvinyl aneol, sin phim (PA) cua hang Peking (Trung Qude)
Cic loai hoa chat khie deu cd do tinh khiet
PA
Ld nung, tu say, m i y khua'y tu, may ly tam, may sieu am va mdt sd dung cu thuy tinh Cic phuang phip xic dinh:
Xic dinh kfeh thude, su phan bd hat bing
m i y Fpar-1000 paticles analyzer cua Hang Orsuka electronic Co Ltd (Nhat Ban)
Chup anh vi ca'u true, kfeh thudc hat va hinh thii hgc cua m i u bing kfnh hiin vi dien td truyin qua (TEM) (Nhat Ban)
Giin dd nhiiu xa Ranghen dugc thuc hien tren may Siemens D-5000 (CHLB Ddc) vdi bdc
xa CuKa budc sdng X = 1,5406 A
Trang 2Ill - KET QUA VA THAO LUAN
1 Anh hudng cua nhiet do nung
Miu dugc diiu che vdi ty le mol Ni/PVA
1/3, nhiet do tao gel 80°C, pH = 4 va nung d cac nhiet do khae nhau trong 2h Cac miu dugc xac dinh kfeh thudc hat tren may Fpar-1000 Ket qua thuc nghiem dugc trinh bay trong bang 1
Bdng 1: Anh hudng cua nhiet do
Nhiet dd nung, °C
Kfeh thudc hat trung binh cua NiO, pm
600 0,206
700 0,694
nung
800 1,092
900 1,265
1000 1,422
Td bang 1 ta nhan thiy nhiet do cang cao thi
kfeh thudc hat cang ldn diiu niy phu hgp vdi ly
thuye't va cdng trinh nghien cdu trudc day [1,2]
Do vay chung tdi chgn 600°C cho cac thf
nghiem tiep theo
2 Anh hudng ciia pH tao gel de'n kich thudc
hat
Diiu kien thi nghiem; ti le ndng do mol
niken va PVA li 1/3, nhiet do tao gel; 80°C, pH
tao gel tu 1 din 5 Cie miu sau khi tao gel dugc
xd ly nhiet d 600°C trong 2h Cac miu duge xic
dinh kfeh thude hat tren may Fpar-1000 Ke't
qua thuc nghiem dugc trinh bay trong bang 2
Qua bang 2 ta thiy kfeh thudc hat nhd nha't tai
pH = 4, kfeh thudc hat ldn nhat d pH = 1 cd thi
mdt phin PVA da phan dng vdi dung dich axit lam cho qua trinh phan bd niken tren polyme khdng dugc ddng nha't, din tdi qua trinh tu hoc chiy cua gel trong qua trinh xd ly nhiet xay ta kem Do dd trong cic thi nghiem tie'p theo chpn
pH = 4 de tao gel
3 Anh hudng cua ti le nong do mol niken va polyvinyl aneol
Cic thi nghiem dugc tie'n hanh vol sir tao gel cua niken va PVA theo ti le ndng do mol: 6/1, 3/1, 1/1, 1/3, 1/6, nhiet do tao gel: 86°C, pH tao gel: 4 Cac miu sau khi tao gel dugc nung 6 600°C trong 2h Cac miu dugc xic dinh kfeh thudc hat tren miy Fpar-1000 Kit qua thuc nghiem dugc trinh biy trong bang 3
Bdng 2: Anh hudng eua pH
pH tao gel
Kich thudc hat trung binh cua NiO, pm
1 0,374
ao gel den kich thudc hat
2 0,335
3 0,266
4 0,206
5 0,313
Bdng 3: Anh hudng cua ti le ndng do mol niken va polyvinyl aneol
Ti le ndng dd mol niken va PVA
Kfeh thudc hat trung binh eua NiO, pm
6/1 1,274
3/1 0,954
1/1 0,757
1/3 0,206
1/6 1,136
Qua bing 3 oxit niken cd kfeh thudc hat be
nha't niu dugc tao gel vdi PVA theo ti le ndng
do mol niken vi polyvinyl aneol la 1/3, cd le d
ty le tao gel nay vda dd cho qua trinh tu bdc
ehiy xay ra mdt each thuan lgi khdng lam kit tu
lai thanh hat ldn hon, edn khi d ty le mol niken/
PVA li 1/6 hoac 6/1 thi kich thudc hat thu duac
la ldn nha't d day, khi nong do niken qua cao thi khd xay ra qua trinh ttf bdc chiy din tdi kfeh thudc hat ldn cdn khi nong do PVA cao thi xay
ra qua trinh chay manh liet Iam cho cac hat lai
cd kha nang lien kit vdi nhau tao ra hat to hon
Do dd trong cic thf nghiem tie'p theo chgn ti le 1/3 de tao gel
Trang 34 Anh hudng cua nhiet do tao gel
Thf nghiem dugc tien hanh vdi su tao gel
cua niken va PVA theo ti le ndng dd mol 1/3,
nhiet do tao gel; 40°C, 60°C, 80°C, 100°C, pH
tao gel; 4 Cac miu sau khi tao gel dugc nung d 600°C trong 2h Dem miu di phan tfch xac dinh kfeh thudc hat trin miy Fpar-1000 Ke't qua thirc nghiem dugc trinh bay trong bang 4
Bdng 4: Anh hudng cua nhiet do tao gel de'n kfeh thudc hat
Nhiet do tao gel | 40°C
Kich thudc hat trung binh cua NiO, pm | 0,399
60°C 0,421
80°C 0,206
100°C 0,447 Bang 4 cho thiy, oxit niken cd kfeh thudc
hat be nhat ne'u dugc tao gel vdi PVA d nhiet do
80°C, diiu nay hoan toan phu hgp vdi cic khao
sat trudc day [2] Chung tdi chgn nhiet do tao
gel la 80°C cho cac nghien cdu sau
5 Anh hudng ciia thdi gian nung
Thf nghiem duge tie'n hanh vdi miu dai dien
la gel cua Nitrat niken va PVA theo ti le ndng
do mol 1/3, nhiet do tao gel 80°C, pH = 4 Cic
miu dugc nung d 600°C trong thdi gian td lh
din 2,5h Cac miu dugc xac dinh kfeh thude hat
tren miy Fpar-1000 Kit qua thuc nghiem dugc
trinh bay trong bang 5
Td bang 5 ta nhan thiy khi nung miu trong
thdi gian td 60 phut din 120 phut thi kich thude
hat nhd din diiu nay ed the do d thdi gian 60
phut va 90 phut miu vin edn mdt phin nhd
hidroeacbon cua gel chua chay he't hinh thinh cac hat to ban cdn d 120 phut thi lugng hidroeacbon da chiy hit len thu dugc kich thudc hat nhd nhat Khi thdi gian tang len 150 phut va 180 phut thi kich thudc hat cung tang len (d day cd the xay ra hien tugng kit hat do khung ca'u trdc eua miu bi sup dd) Do vay eac nghien cdu tie'p theo ehdng tdi chgn thdi gian nung la 120 phdt
Chung tdi chgn miu diiu che d pH = 4, ty le niken/PVA = 1/3, nhiet do tao gel 80°C, nhiet do nung 600°C trong 120 phut dem xic dinh cau true bang nhiiu xa tia X, hinh thii hgc bang kfnh hien vi dien td truyen qua(TEM) vi su phan bd kfeh thudc hat trung binh cua NiO bing miy Fpar-1000 paticles analyzer Kit qui trinh biy d Itinh 1, 2 vi 3
Bdng 5: Anh hudng
Thdi gian nung, phdt
•Kich thudc hat trung binh, cua NiO, pm
cua thdi g
60 0,255
an nung
90 0,225
120 0,206
150 0,320
180 0,421
Hitih 1: Anh TEM cua NiO
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Hinh 2: Su phan bo kich thirdc hat trung binh cua NiO
iiEnENS D s a a e ,
0 6 i SS3.33Qd3, UL
Hinh 3: Gian dd tia X cua NiO
Ta tha'y NiO thu dugc la dan pha (hinh 3),
ddng nha't ed kich thudc < 50 nm (hinh 1) va
dugc phan bd tap trung vdi kfeh thudc hat NiO
trung binh 206,1 nm = 0,206 pm (hinh 2) Sd dt
cd su khic nhau vi kich thudc hat cua NiO khi
chup TEM vi xac dinh kfeh thudc hat trung binh,
theo chdng tdi, diiu nay la do cic hat NiO tao
thanh cd the kit tu lai vdi nhau de tao thinh mot chum hat hay NiO cd ca'u true nano (hinh 1)
IV - KET LUAN
Da khao sit cic ye'u td anh hudng tdi Icfch thudc hat NiO va da tim dugc diiu kien tdi uu
Trang 5de tdng hgp NiO dan pha cd kfeh thudc < 50 nm
vdi kfeh thudc hat NiO trung binh 206,1 nm =
0,206 pm bing qua trinh tu bd'e chiy gel PVA
la: pH = 4, ti le ndng do mol niken/PVA =1/3,
nhiet do tao gel 80°C, nhiet dd nung 600°C trong
120 phut
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Tdc gid lien he: Luu Minh Dai
Vien Khoa hgc Vat lieu, Vien Khoa hgc va Cdng nghe Viet Nam