Borate Phosphors

Processing to Applications

S. K. Omanwar, R. P. Sonekar, N. S. Bajaj, S. K. Omanwar, R. P. Sonekar, N. S. Bajaj

• Publisher: CRC Press
• Year: 2022
• Print ISBN: 9781032075747
• eBook ISBN: 9781000581263
• Topic: Physical Sciences
• Subtopic: Electrical Engineering & Telecommunications

Borate-based phosphors have attracted much attention, due to their high optical stability, low-cost synthesis via conventional and non-conventional methods and resulting technology to be environmentally friendly. This book discusses the structural and chemical parameters of borates as a phosphor including suitable synthesis methods and proper characterization of materials. Further, it includes applications of borate materials such as photoluminescence, UV application, UVU application, photo therapy application and radiological applications.

Features:

• Provides information on borate phosphors and their structure.
• Aids selection of proper structural and functional borates used in applications based on phosphor technology.
• Discloses the modification in properties of borate functional group upon mixing or substitution with other metallic functional groups.
• Discusses biological applications such as photo-thermal heating-based therapy, temperature sensors, imaging, and diagnosis.
• Includes current trends and innovations, limitations and challenges, prospects, and scope in each chapter.

This book is aimed at researchers and graduate students in inorganic materials, luminescent/optical materials, materials science/engineering, and physics.

1 Introduction to Borate Phosphors

P. K. Tawalare and A. B. Gawande

DOI: 10.1201/9781003207757-1

CONTENTS

1. 1.1 Introduction
2. 1.2 Phosphors
3. 1.3 Applications of Phosphors
4. 1.3.1 Luminescence Phenomenon
5. 1.3.1.1 Principle
6. 1.3.1.2 Excitation
7. 1.3.1.3 Emission
8. 1.3.1.4 Decay Characteristics
9. 1.3.1.5 Mechanism
10. 1.4 Borate-Based Phosphors
11. 1.4.1 Classification of Borates
12. 1.4.1.1 Classification of Borates Based on Chemical Formula
13. 1.4.1.2 Classification of Borates Based on Crystal Structure
14. 1.4.2 Crystal Chemistry of Borates
15. 1.4.3 Applications of Borate Host Materials as Phosphors
16. 1.4.3.1 Inorganic Borate as NLO and LASER Material
17. 1.4.3.2 Inorganic Borate as Phosphor Material
18. 1.4.4 Mixed Borate Phosphors
19. References

1.1 Introduction

The varied aspects of luminescence and the complex processes involved in the origin of light emission, offer interesting challenges for researchers in this field. This is one of the research fields, wherein diverse application area exists, which range from radiation monitoring for health and safety, phosphors for lamps and display purposes to X-ray imaging and other means of medical diagnostics.

Luminescence is a well-established field of scientific research. In 1652, Zechi made an important contribution to the understanding of photoluminescence. It is the emission of light, which persists after the excitation agency, is removed (luminescence). Moreover; he proved experimentally that the color of the phosphorescence light in a material is independent of the color of the exciting light and also clearly distinguished the phenomenon from scattering. About 200 years later, Stoke showed that the incident and emitted light differed in color and enunciated his well-known Stoke's law regarding the increase in wavelength, which accompanies photoluminescence. In 1867, E. Bequerel distinguished two types of phosphorescence or after-glow, which were attributed respectively to monomolecular and to bimolecular decay mechanism.

The last few decades have witnessed dramatic changes in research on luminescence. There has been a phenomenal growth in the subject, and a significant progress has been made in the field of luminescence research. Recent research is characterized by strong interaction among other branches of solid-state physics and between different areas of luminescence using inorganic and organic materials. Both experimental as well as theoretical approaches have been made.

Luminescent materials are called phosphors. The first systematic study of luminescent crystals was made by Lenard [1] and his school, at the beginning of the 20th century. The phosphors they studied are called ‘Lenard Phosphors’. The practical interest in luminescent materials for use in efficient cathode ray screens, and eventually for luminescent lamps, which were then developed in 1930s, stimulated the study of crystal luminescence in a very substantial way.

1.2 Phosphors

Phosphors are solid, luminescent materials that emit photons when excited by an external energy source, such as an electron beam (cathodoluminescence) or ultraviolet light (photoluminescence). Phosphors are composed of an inert host lattice, which is transparent to the excitation radiation and an activator, typically a 3d or 4f electron metal, which is excited under energy bombardment. The process of luminescence occurs by adsorption of energy at the activator site, relaxation, and subsequent emission of a photon and a return to the ground state. The efficiency of a phosphor depends on the amount of relaxation that occurs during the activation and emission. Relaxation is the process in which energy is lost to the lattice as heat; it needs to be minimized in order to extract the highest luminous efficiency. The luminous efficiency is defined as the ratio of the energy emitted to the energy absorbed.

1.3 Applications of Phosphors

The substantial advances in understanding luminescent phenomena and the discoveries of unusual luminescent processes, for example, up-conversion and quantum splitting, present unusual opportunities for the applications of luminescence. In some instances, these possible applications depend on improvements in efficiencies and stabilities of inorganic luminescent materials; in other instances, on the problems of adapting the available scientific understa...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Contents
• Preface
• Editors’ Biographies
• List of Contributors
• Chapter 1 Introduction to Borate Phosphors
• Chapter 2 Borate Phosphor: Synthesis and Characterization
• Chapter 3 Borate Phosphors: Lamp Phosphors
• Chapter 4 Borate Phosphors for Solid-State Lighting
• Chapter 5 Borate Phosphor for Phototherapy Application
• Chapter 6 Borate Phosphor: PDP Phosphor
• Chapter 7 Borate Phosphors for Radiation Dosimetery
• Chapter 8 Borate Phosphors: NIR Quantum Cutting Phosphors
• Chapter 9 Borate Phosphor: Mechanoluminescence and Lyoluminescence Phosphors
• Chapter 10 Borate Phosphors for Neutron Radiography
• Index