Nanocomposite Based on HA/PVTMS/Cl₂FeH₈O₄ as a Gas and Temperature Sensor

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Hydroxyapatite (HA) is sensitive to high temperatures, requiring protective measures during composite fabrication.
• Nanocrystalline composite materials offer unique properties for sensor applications.
• Developing stable and selective gas sensors is crucial for environmental monitoring and industrial processes.

Purpose of the Study:

• To synthesize and characterize a novel nanocrystalline composite material (HA/PVTMS/iron(II)chloride tetrahydrate) for gas/temperature sensing.
• To design and fabricate a specialized freeze-drying machine to preserve the composite structure.
• To investigate the sensing performance of the composite-based sensor towards various gases.

Main Methods:

• Fabrication of a hexagonal nanocrystalline composite material using hydroxyapatite, polyvinyltrimethoxysilane, and iron(II)chloride tetrahydrate.
• Utilized a custom-designed freeze-drying machine to maintain composite integrity.
• Characterization techniques included X-ray diffraction (XRD), FTIR, SEM, EDAX, TEM, absorption, and photoluminescence spectroscopy.
• Fabrication and testing of a SiO2/composite/Ag sensor device.

Main Results:

• The nanocrystalline composite exhibited a hexagonal structure with a crystallite size of 81.60 ± 0.06 nm.
• Absorption and photoluminescence properties were studied, considering the influence of the oxygen environment.
• The sensor demonstrated the highest response to vaporized ethanol, N2, and ambient CO with a 30 nm composite layer.
• The composite and sensor showed good selectivity towards oxygen, ethanol, N2, and CO.

Conclusions:

• The novel HA/PVTMS/iron(II)chloride tetrahydrate composite is suitable for gas and temperature sensor fabrication.
• The developed freeze-drying method effectively preserves the composite structure.
• The sensor exhibits promising selectivity and response to key environmental gases.