Effect of Zn Site for Ca Substitution on Optical and Microwave Dielectric Properties of ZnAl2O4Thin Films by Sol Gel Method

Jalal, Wan Nasarudin Wan; Abdullah, Huda; Zulfakar, Mohd Syafiq

doi:10.1155/2014/619024

Cited by 5 publications

(2 citation statements)

References 36 publications

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“…The lattice vibrational modes, porosity, secondary phases, lattice defects, crystallizability and inner stress influence the value of Q u [24,28]. The unloaded quality factor of ZnAL 2 O 4 is consistent with that previously reported by Surendran et al [29] and Wan Nasarudin et al [30].…”

Section: Quality Factorsupporting

confidence: 89%

Synthesis and characterization of gahnite-based microwave dielectric ceramics (MDC) for microstrip antennas prepared by a sol–gel method

Rahman

Islam

Zulfakar

et al. 2015

J Sol-Gel Sci Technol

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Gahnite (zinc aluminate) nanoparticle powder is synthesized by a sol-gel method and used to fabricate a microstrip antenna. X-ray diffraction analysis indicates the formation of a face-centered cubic gahnite structure with an average crystallite size of 19.92 nm. The surface morphology of the gahnite is analyzed with field-emission scanning electron microscopy. The presence of water molecules and nitrates within the material is confirmed by Fourier transform infrared analysis. The measured dielectric constant, bandgap and unloaded quality factor of the synthesized powder are 8.70, 4.08 eV and 4592, respectively. The performance of the microstrip antenna is evaluated using return loss, (S11) parameter analysis. The measured impedance bandwidth is 760 MHz in the lowfrequency band and 8.1 GHz in the high-frequency band. The overall performance demonstrates that the fabricated ceramic is suitable for application in a microstrip antenna. Graphical Abstract

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Section: Quality Factorsupporting

confidence: 89%

Synthesis and characterization of gahnite-based microwave dielectric ceramics (MDC) for microstrip antennas prepared by a sol–gel method

Rahman

Islam

Zulfakar

et al. 2015

J Sol-Gel Sci Technol

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“…However, there are many barriers for female engineers to enter the engineering workforce, the most significant of which is the marginalization of female engineers in a dominated masculine culture that considers women to be weak, less capable and less productive employees who are unable to travel to work sites, perform duties during at night or interact with male counterparts and clients (Wan Jalal et al , 2014). This mindset negatively impacts the recruitment of female engineers in both the private and public sectors, as illustrated in job announcements requiring male applicants.…”

Section: Literature Review and Statement Of Research Questionsmentioning

confidence: 99%

Female Afghan engineers’ perceptions of chokepoints along the career trajectory to entrepreneurship

Mehrzad¹,

Dasanayaka²,

Gleason³

et al. 2021

JEEE

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Purpose The purpose of this study is to explore the perceptions of Afghan female engineers regarding opportunities and barriers to starting their own engineering/construction company in Kabul through three career trajectory chokepoints related to training through higher education, the engineering workplace and entrepreneurship, through the lens of feminist theory. Design/methodology/approach Semi-structured in-depth interviews were conducted. A Web-based survey was also conducted to collect data from participants who were not able to participate in the in-depth interviews. Thematic content analysis was used to analyze the collected data. Findings As a result of the analysis, three main themes were developed related to “chokepoints” that Afghan female engineers face along the path to starting their own construction companies: “entering and studying engineering,” “career development” and “starting her own engineering business”; the authors address the subthemes of barriers and opportunities confronted by Afghan women at each chokepoint. Research limitations/implications Due to civil unrest, the authors are only able to reach a sample of Afghan female engineers working in the capital city of Kabul. Practical implications Afghanistan shows, perhaps, the most severe underrepresentation of female engineers of all countries in the world, yet no research gives them a voice to explain the challenges their face to starting their own engineering/construction businesses. The authors are able to report their perceptions and articulate recommendations to encourage female entrepreneurship in the engineering/construction sector in Afghanistan. Social implications Afghan women face significant barriers to having meaningful careers in the science, technology, engineering and medicine professions. The findings provide information for regulators regarding why Afghan women do not start their own engineering firms. Originality/value As physical security and resource constraints generate difficulty in accessing Afghan women in general, this is the first paper to report the perceptions of Afghan female engineers regarding the barriers and opportunities they perceive on the path to engineering entrepreneurship.

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Synthesis and fabrication of GPS patch antennas by using Zn(1 − x)Ti x Al2O4 thin films

Jalal

Abdullah

Zulfakar

et al. 2015

J Sol-Gel Sci Technol

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Zn (1 -x) Ti x Al 2 O 4 -based microwave dielectric ceramics were prepared by sol-gel method. The obtained compounds were characterized and fabricated as GPS patch antennas. The XRD patterns show a three-phase system with a spinel ZnAl 2 O 4 , anatase and a rutile (TiO 2 ). The addition of TiO 2 increased the crystallite size and grain size, and surface morphology tended to increase the ceramics density (4.61-4.75 g/cm 3 ) and dielectric constant, e r (8.56-13.51). Based on the material investigated and microwave antenna theory, GPS patch antennas were fabricated using Zn (1 -x) Ti x Al 2 O 4 and then measured using a PNA series network analyzer. The surface of the GPS patch antennas and ground plane was coated with 200-nm-thick silver to enhance ohmic contact. The patch antenna sizes decreased as e r increased from 2.88 9 4.37 cm (12.58 cm 2 ) to 3.53 9 2.21 cm (7.80 cm 2 ). Among these antennas, the Zn 0.70 Ti 0.30 Al 2 O 4 shows an excellent performance combination between return loss (-28.71 dB), small size (3.53 9 2.21 cm), and wide bandwidth (270 MHz). Graphical Abstract

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Effect of Zn Site for Ca Substitution on Optical and Microwave Dielectric Properties of ZnAl₂O₄Thin Films by Sol Gel Method

Cited by 5 publications

References 36 publications

Synthesis and characterization of gahnite-based microwave dielectric ceramics (MDC) for microstrip antennas prepared by a sol–gel method

Synthesis and characterization of gahnite-based microwave dielectric ceramics (MDC) for microstrip antennas prepared by a sol–gel method

Female Afghan engineers’ perceptions of chokepoints along the career trajectory to entrepreneurship

Synthesis and fabrication of GPS patch antennas by using Zn(1 − x)Ti x Al2O4 thin films

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