Kajian karakteristik fisis zeolit alam sebagai lapisan dielektrik piranti elektronika
PURWATI, Dr. Kuwat Triyana
2006 | Tesis | S2 Ilmu FisikaTelah dilakukan kajian karakterisasi fisis zeolit alam sebagai lapisan dielektrik piranti elektronika, meliputi pemurnian zeolit alam dan karakterisasi. Zeolit merupakan kristal alumino-silika yang memiliki struktur berongga atau berpori dengan ukuran yang relatif seragam. Struktur zeolit mirip de ngan silika, yang diharapkan memiliki konstanta dielektrik rendah. Pemisahan partikel menggunakan teknik gravitasi, setelah zeolit diaduk dengan stirrer. Kemudian zeolit dipanaskan sampai 300, 350, 400, dan 450oC. Komposisi kimia dari zeolit dikarakterisasi meliputi: aktivasi peluruhan netron cepat (APNC), analisa spektroskopi serapan atom (AAS), pengukuran gravimetri. Struktur kristal dari zeolit dikarakterisasi dengan difraksi sinar-x (XRD). Luas permukaan dari zeolit diketahui dengan analisis luas permukaan (gas sorption analyzer). Mengestimasi keasaman zeolit dengan methyl orange (MO). Struktur kimia diperoleh dengan analisis dasar untuk zeolit murni [Na0,21Mg0,94Fe0,06K0,095Ca0,095(H2O)15,34] [Si40Al7,87O95,74], rasio Si/Al 5,1. Zeolit asal [Na0,71Mg0,83Fe0,058K0,017Ca0,011(H2O)11,75][Si40Al9,81O99,62 ], rasio Si/Al 4,1. Mengindikasikan bahwa zeolit murni memiliki perbandingan rasio Si/Al lebih baik. Nilai absorbansi methyl orange (MO) paling tinggi pada zeolit murni yang dipanaskan sampai 350oC dan zeolit asal yang dipanaskan sampai 300oC, mengindikasikan bahwa zeolit murni memiliki asam Bronsted lebih banyak. Luas permukaan spesifik zeolit murni sebesar 60,22 m2/g, zeolit murni yang dipanaskan sampai 350°C sebesar 47,53 m2/g, dan zeolit asal sebesar 21,98 m2/g, terjadi peningkatan luas penampang yang signifikan.Volume pori total zeolit murni sebesar 48,35 mL/g, zeolit murni yang dipanaskan sampai 350°C sebesar 41,53 mL/g, sedang zeolit asal sebesar 20,09 mL/g. Perubahan pola difraksi sinar-x terjadi pada zeolit murni dan zeolit yang dipanaskan sampai 450°C, mengindikasikan zeolit tidak stabil pada temperatur tinggi. Konstanta dielektrik zeolit murni sebesar 4,7 lebih kecil dari zeolit asal sebesar 11. Penurunan konstanta dielektrik yang signifikan dari zeolit murni, diharapkan dapat membuktikan karakterisasi fisis maupun kimia.
Physical characteristics of natural zeolite have been studied for possible application as dielectric layer of electrical devices following the purification process. Zeolite is a naturally available alumino-silicate mineral having porous structure and relatively uniform in size. Having similarity in structure to that of silica, zeolite is expected to bear a low dielectric constant especially after being purified. The gravity size fraction technique was applied to purify the zeolite after dispersing it in distilled water. This was followed by calcinations at 300, 350, 400, and 450oC. Elemental composition of the material was determined by neutron activation, atomic absorption spectrometry, and gravimetric method for the interlayer water. The crystal structure of the zeolite was determined by X-ray diffraction. The surface area was measured by nitrogen sorption. Methyl orange was used to estimate the acidity of the zeolite powder. The chemical structure as determined by the results of the elemental analysis for the purified zeolite is [Na0.21K0.095Mg0.94Fe0.06Ca0.095(H2O)15.34] [Si40Al7.87O95.74] where the molar ratio of Si/Al is 5.1. Meanwhile, the unpurified zeolite has the structure of [Na0.71K0.017Mg0.83Fe0.058Ca0.011(H2O)11.75] [Si40Al9.81O99.92] in which the molar ratio of Si/Al is 4.1. This indicates that the purified material has a better Si/Al ratio. The largest increase in absorbance of methyl orange at low wavelength was obtained for the purified zeolite heated at 350oC and for unpurified one heated at 300 oC indicating that the purified zeolite has more Bronsted acid sites. The specific surface area of the purified zeolite is 60.22 m2 /g, and remains high at 47.53 m2/g after being calcined at 350oC compared to only 21.98 m2/g for unpurified zeolite, suggesting a significant increase in surface area. As well, the total pore volume was up from 41.53 mL/g to 48.35 mL/g. A change in the X-ray diffraction pattern was seen for both purified and unpurified zeolite after being heated at 450oC, suggesting thermal instability at high temperature. The dielectric constant of purified zeolite is only 4.7 much lower than unpurified one which is 11. A significant reduction of dielectric constant of purified zeolite is expected as a result of its improved physical and chemical characteristics.
Kata Kunci : Zeolit Alam,Konstanta Dielektrik, natural zeolite, dielectric constant, acidity, methyl orange
