Date of Award

2020-01-01

Degree Name

Master of Science

Department

Mechanical Engineering

Advisor(s)

Chintalapalle Ramana

Abstract

In this work, we report on the synthesis, characterization, and performance of LiGaP2O7 (LGP), a novel material and fairly new to the scientific & engineering community. LiGaP2O7 materials were was synthesized using the conventional high-temperature, solid-state ceramic reaction. Calcination was done in three steps at the temperatures of 300 °C, 500 °C, and 650 °C for 8 h each to ensure a single phase. Utilizing this, different green pellets were sintered at 800 °C for varying times of 3 h, 6 h, 12 h, and 24 h. The structure, phase, and morphology were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Furthermore, structural refinement was done utilizing the Rietveld method. The crystallite size decreased, grain size increased, and the volume of the unit cell decreased due to increasing sintering time. The dielectric properties of LGP samples were measured as a function of temperature and frequency. The modified Debye's equation and Cole-Cole plot were used, which indicated multiple ions were responsible for dielectric relaxation. The dielectric constant decreases as a function of increasing frequency, indicating a lack of polarization sources contribution and increases as a function of increasing temperature, indicating thermal activation of charge carriers. The study of the type of conduction mechanism using AC conductivity indicated at hoping type conduction.

The LGP films were deposited by pulsed-laser deposition (PLD) using a target (sintered at 800 °C for 12 h). The substrate temperature (Ts) was varied from 25 to 700 °C to. The PLD LGP films were nanocrystalline at ≥500 °C. Spectroscopic ellipsometry analyses indicate a decrease in film thickness and refractive index with Ts. Moreover, the extinction coefficient suggested luminance at a specific frequency. Second-harmonic generation (SHG) measurements were made to measure the nonlinear optical properties. The results indicated the dependency of SHG signal on the structure and morphology of LGP films. The structure-property correlation is established.

Language

en

Provenance

Received from ProQuest

File Size

76 pages

File Format

application/pdf

Rights Holder

Mohan Raj Rajkumar

Available for download on Thursday, February 25, 2021

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