자료유형  

 학위논문

Control Number  

0017164435

International Standard Book Number  

9798346393108

Dewey Decimal Classification Number  

537.62

Main Entry-Personal Name  

Garcia, Javier Mena.

Publication, Distribution, etc. (Imprint  

[S.l.] : The Pennsylvania State University., 2024

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2024

Physical Description  

145 p.

General Note  

Source: Dissertations Abstracts International, Volume: 86-05, Section: B.

General Note  

Advisor: Randall, Clive A.

Dissertation Note  

Thesis (Ph.D.)--The Pennsylvania State University, 2024.

Summary, Etc.  

요약This dissertation presents a comprehensive investigation into the synthesis, characterization, and application of ceramic-polymer composites and ceramic matrix composites (CMC) through the cold sintering process. With a primary focus on understanding the relationship between the designed composites' microstructures and their physical properties, this research integrates the results and learnings from four integral studies to elucidate the multifaceted aspects of materials science and engineering.The initial study explores into the design of ceramic-polymer composites, integrating the ferroelectric co-polymer polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) at the grain boundaries of a semiconducting zinc oxide (ZnO) matrix. Through a synergistic approach encompassing electrical conductivity modeling, dielectric characterization, and transmission electron microscopy (TEM) investigation, the study unveils the pivotal role of PVDF-TrFE in modulating the electrical properties of the composite, with an average thickness of 3 nm of PVDF-TrFE at the grain boundaries of ZnO measured by TEM and confirmed by calculations based on the Maxwell-Wagner-Sillars (MWS) effect. The addition of only 2 vol.% of PVDF-TrFE was sufficient to improve the non-linear conductivity and enable the Fowler-Nordheim tunneling mechanism at high applied electric fields, with a low barrier height of qφB = 0.1 eV. The critical electric field per grain boundary to transition from Schottky thermionic emission at low electric fields to Fowler-Nordheim tunneling was identified at 2.6 V•nm-1.Subsequent investigations underscore pressing necessity for advanced dielectric substrates tailored to the demands of modern 5G and 6G communication technologies. Employing sodium molybdate (Na2Mo2O7, NMO) as the ceramic matrix and hexagonal boron nitride (hBN) as the filler, dense CMCs are fabricated to augment the thermal conductivity from 2 to 12 W•m-1K-1, and to improve the dielectric properties by decreasing the relative permittivity from 13 to 8, at 106 and 9-13 GHz frequencies, with the addition of 50 vol.% of hBN. The dielectric loss of the composites was lower than 8x10-4at microwave frequencies. The following exploration extends this paradigm by incorporating diamond as a filler, aiming to further enhance thermal conductivity while maintaining minimal dielectric loss, thus elucidating the potential of engineered CMCs as versatile microwave substrate materials.Integral to the thesis is an in-depth analysis of the densification process of the NMO ceramic matrix phase, cold sintered in conjunction with filler materials of hBN and micro diamond (md). Through examination of kinetics, mechanisms, and microstructural changes, including pressure solution creep and steady-state creep processes induced by applied stress and variation of temperatures, this study describes the densification behavior and underscores the transformative impact of filler materials on mechanical and thermal properties. A dilatometry study allowed to identify activation energies between 48 and 97 kJ/mol for the NMO, NMO-hBN and NMO-md samples, using the Woolfrey-Bannister method. Norton's equation was used to estimate activation energy of 36 kJ/mol for NMO and the NMO-md composites, in the isothermal region of the steady-state creep. Determination of n stress exponent was used to identify the creep mechanisms of diffusional transport (n~1) for NMO and sliding interfaces (n~2) for NMO-md composites.By synthesizing findings from these interconnected studies, this thesis contributes to a holistic understanding of CSP-derived composites, offering valuable insights into their potential applications across a spectrum of communication technologies and microwave substrate materials.

Subject Added Entry-Topical Term  

Dielectric properties.

Subject Added Entry-Topical Term  

Cold.

Subject Added Entry-Topical Term  

Thermal energy.

Subject Added Entry-Topical Term  

Grain boundaries.

Subject Added Entry-Topical Term  

Microstructure.

Subject Added Entry-Topical Term  

Densification.

Subject Added Entry-Topical Term  

Sintering.

Subject Added Entry-Topical Term  

Ceramics.

Subject Added Entry-Topical Term  

Composite materials.

Subject Added Entry-Topical Term  

Crystal structure.

Subject Added Entry-Topical Term  

Polymers.

Subject Added Entry-Topical Term  

Motivation.

Subject Added Entry-Topical Term  

Electric fields.

Subject Added Entry-Topical Term  

Zinc oxides.

Subject Added Entry-Topical Term  

Design.

Subject Added Entry-Topical Term  

Particle size.

Subject Added Entry-Topical Term  

Density.

Subject Added Entry-Topical Term  

Atoms & subatomic particles.

Subject Added Entry-Topical Term  

Atomic physics.

Subject Added Entry-Topical Term  

Electromagnetics.

Subject Added Entry-Topical Term  

Energy.

Subject Added Entry-Topical Term  

Materials science.

Subject Added Entry-Topical Term  

Polymer chemistry.

Added Entry-Corporate Name  

The Pennsylvania State University.

Host Item Entry  

Dissertations Abstracts International. 86-05B.

Electronic Location and Access  

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Control Number  

joongbu:655251