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Agricultural wastes as a resource of raw materials for developing low-dielectric glass-ceramics.

Danewalia SS, Sharma G, Thakur S, Singh K - Sci Rep (2016)

Bottom Line: Sugarcane leaves ash exhibits higher content of alkali metal oxides than rice husk ash, which reduces the melting point of the components due to eutectic reactions.The presence of less ordered augite phase enhances the dielectric permittivity as compared to cristobalite and tridymite phases.The glass-ceramics developed with adequately devitrified phases can be used in microelectronic devices and other dielectric applications.

View Article: PubMed Central - PubMed

Affiliation: School of Physics and Materials Science, Thapar University, Patiala-147004, India.

ABSTRACT
Agricultural waste ashes are used as resource materials to synthesize new glass and glass-ceramics. The as-prepared materials are characterized using various techniques for their structural and dielectric properties to check their suitability in microelectronic applications. Sugarcane leaves ash exhibits higher content of alkali metal oxides than rice husk ash, which reduces the melting point of the components due to eutectic reactions. The addition of sugarcane leaves ash in rice husk ash promotes the glass formation. Additionally, it prevents the cristobalite phase formation. These materials are inherently porous, which is responsible for low dielectric permittivity i.e. 9 to 40. The presence of less ordered augite phase enhances the dielectric permittivity as compared to cristobalite and tridymite phases. The present glass-ceramics exhibit lower losses than similar materials synthesized using conventional minerals. The dielectric permittivity is independent to a wide range of temperature and frequency. The glass-ceramics developed with adequately devitrified phases can be used in microelectronic devices and other dielectric applications.

No MeSH data available.


Related in: MedlinePlus

Variation in dielectric permitivity with frequency for the glass-ceramics at (a) 250 °C (b) 350 °C.
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f5: Variation in dielectric permitivity with frequency for the glass-ceramics at (a) 250 °C (b) 350 °C.

Mentions: Here, the symbols have their usual meanings. The variation of dielectric permittivity (ε′) versus frequency for present glass-ceramics is presented in Fig. 5. The dielectric data clearly shows the low tanδ (losses) in the glass-ceramics. Secondly, the dielectric permittivity of the samples is nearly independent of frequency from room temperature to 250 °C. At higher temperatures (>350 °C), dielectric permittivity increases sharply, particularly for lower frequency region. R-50 exhibits maximum ϵ′ followed by R-25, R-00, R-100 and R-75. Dielectric permittivity of present samples is nearly proportional to the modifier content. It can be co-related with the highly mobile nature of the alkali and alkaline earth ions. Conduction in the glass-ceramics is dominated by the hopping of the alkali ions. Hopping of ions becomes easier with higher defects, which act as hopping sites. This may be the reason for highest dielectric permittivity of R-50 (higher NBOs) as compared to other samples. R-100 and R-75 contain very low modifier cations, which leads to lower dielectric permittivity. Similar high silica compositions, when synthesized by conventional minerals, show low dielectric permittivity, but higher losses than present samples39. Additionally, the higher volume fraction of crystalline phases may increase the electronic conduction as compared to ionic conduction, which could be responsible to decrease the dielectric permittivity. Basically, the decreased ionic motion reduces the dielectric permittivity40. As mentioned in XRD section, R-50 formed augite phase, which has monoclinic prismatic structure. It is disordered structure as compared to tetragonal cristobalite and hexagonal tridymite phases. More disordered structure makes the system relatively more polar in the presence of the applied field. R-00 and R-25 formed diopside, which is monoclinic and closely related to augite. It makes these samples to have higher dielectric permittivity as compared to ordered R-75 and R-100 samples. Increase in dielectric permittivity of R-00, R-25 and R-50 at lower frequencies is usual behaviour and can be explained on the basis of Maxwell-Wagner dielectric theory41. At lower frequencies, the space charge polarisation plays a dominant role and increases the dielectric permittivity. This effect predominates at high temperatures, where the thermal vibrations facilitate the ionic motion due to increased mobility. These mobile charge are accumulated at the surface of the material and enhances the dielectric permittivity42. Therefore, at low frequencies and higher temperatures, the dielectric permittivity of the glass-ceramics increases.


Agricultural wastes as a resource of raw materials for developing low-dielectric glass-ceramics.

Danewalia SS, Sharma G, Thakur S, Singh K - Sci Rep (2016)

Variation in dielectric permitivity with frequency for the glass-ceramics at (a) 250 °C (b) 350 °C.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834533&req=5

f5: Variation in dielectric permitivity with frequency for the glass-ceramics at (a) 250 °C (b) 350 °C.
Mentions: Here, the symbols have their usual meanings. The variation of dielectric permittivity (ε′) versus frequency for present glass-ceramics is presented in Fig. 5. The dielectric data clearly shows the low tanδ (losses) in the glass-ceramics. Secondly, the dielectric permittivity of the samples is nearly independent of frequency from room temperature to 250 °C. At higher temperatures (>350 °C), dielectric permittivity increases sharply, particularly for lower frequency region. R-50 exhibits maximum ϵ′ followed by R-25, R-00, R-100 and R-75. Dielectric permittivity of present samples is nearly proportional to the modifier content. It can be co-related with the highly mobile nature of the alkali and alkaline earth ions. Conduction in the glass-ceramics is dominated by the hopping of the alkali ions. Hopping of ions becomes easier with higher defects, which act as hopping sites. This may be the reason for highest dielectric permittivity of R-50 (higher NBOs) as compared to other samples. R-100 and R-75 contain very low modifier cations, which leads to lower dielectric permittivity. Similar high silica compositions, when synthesized by conventional minerals, show low dielectric permittivity, but higher losses than present samples39. Additionally, the higher volume fraction of crystalline phases may increase the electronic conduction as compared to ionic conduction, which could be responsible to decrease the dielectric permittivity. Basically, the decreased ionic motion reduces the dielectric permittivity40. As mentioned in XRD section, R-50 formed augite phase, which has monoclinic prismatic structure. It is disordered structure as compared to tetragonal cristobalite and hexagonal tridymite phases. More disordered structure makes the system relatively more polar in the presence of the applied field. R-00 and R-25 formed diopside, which is monoclinic and closely related to augite. It makes these samples to have higher dielectric permittivity as compared to ordered R-75 and R-100 samples. Increase in dielectric permittivity of R-00, R-25 and R-50 at lower frequencies is usual behaviour and can be explained on the basis of Maxwell-Wagner dielectric theory41. At lower frequencies, the space charge polarisation plays a dominant role and increases the dielectric permittivity. This effect predominates at high temperatures, where the thermal vibrations facilitate the ionic motion due to increased mobility. These mobile charge are accumulated at the surface of the material and enhances the dielectric permittivity42. Therefore, at low frequencies and higher temperatures, the dielectric permittivity of the glass-ceramics increases.

Bottom Line: Sugarcane leaves ash exhibits higher content of alkali metal oxides than rice husk ash, which reduces the melting point of the components due to eutectic reactions.The presence of less ordered augite phase enhances the dielectric permittivity as compared to cristobalite and tridymite phases.The glass-ceramics developed with adequately devitrified phases can be used in microelectronic devices and other dielectric applications.

View Article: PubMed Central - PubMed

Affiliation: School of Physics and Materials Science, Thapar University, Patiala-147004, India.

ABSTRACT
Agricultural waste ashes are used as resource materials to synthesize new glass and glass-ceramics. The as-prepared materials are characterized using various techniques for their structural and dielectric properties to check their suitability in microelectronic applications. Sugarcane leaves ash exhibits higher content of alkali metal oxides than rice husk ash, which reduces the melting point of the components due to eutectic reactions. The addition of sugarcane leaves ash in rice husk ash promotes the glass formation. Additionally, it prevents the cristobalite phase formation. These materials are inherently porous, which is responsible for low dielectric permittivity i.e. 9 to 40. The presence of less ordered augite phase enhances the dielectric permittivity as compared to cristobalite and tridymite phases. The present glass-ceramics exhibit lower losses than similar materials synthesized using conventional minerals. The dielectric permittivity is independent to a wide range of temperature and frequency. The glass-ceramics developed with adequately devitrified phases can be used in microelectronic devices and other dielectric applications.

No MeSH data available.


Related in: MedlinePlus