dc.description.abstract |
About a decade ago, one of us (WMY), in response to a federal broad agency
announcement, initiated an effort to establish a baseline for the state of knowledge
concerning the methodology for synthesis and the optical properties of a variety of
phosphors used for display and other technical applications. Though for various reasons this
effort ultimately turned futile, several members of the phosphor/luminescence community
called my attention to an existing backlog of published and unpublished literature addressed
to this subject. This resulted, for example, in our becoming aware of the existence of the
Phosphor Handbook published in Japanese under the auspices of the Japan Phosphor
Society and led to its eventual translation and publication as the Phosphor Handbook, a
volume in the CRC Lasers and Optical Sciences and Technology Series.
In connection with efforts to establish a phosphor database, Ronald Petersen (of Motorola, at
the time) first presented us with a copy of Willi Lehmann’s opus (Phosphor Cookbook) on
methods for synthesis and properties of over 200 phosphors. This report dates from the late
1970’s and covered the majority of phosphors then in use. Dr. Lehmann, of course, was a
principal in the development of many of the phosphors included in his cookbook. He later
updated and extended this work in 1988 in his Phosphor Tables in which the phosphor
properties of over 300 luminescent materials were summarized in tabular form. A copy of
these tables, which was prepared for a publication that never appeared, was preserved and
given to us by Dr. Henry Ivey. Henry had a close working relationship with Willi at
Westinghouse as the Foreword to this volume attests.
The scholarship contained in the Phosphor Cookbook and the Phosphor Tables is quite
remarkable and comprises a great deal of meticulous and careful work characterizing Willi
Lehmann’s career as a phosphor synthesizer. The list of materials presented in the
compilations is large and the manuscripts preserve and summarize synthesis and optical data
on most of the commonly used phosphors (as well as some less common ones). In the
absence of any systematic database on phosphors, the two unpublished manuscripts
represent a reasonably complete summary of the state of knowledge on phosphors up to the
late 1980’s.
Though it might be argued that the art of phosphors synthesis and characterization has
advanced considerably since Lehmann’s time, we believe that these contributions need to be
preserved as part of the phosphor art. Thus, it appeared to us that the content of these two
unpublished manuscripts fully deserved publication as a record, if nothing else, of past
methodologies; these methodologies are often abandoned and forgotten but often need to be
rediscovered and revived when circumstances warrant it. Almost all modern phosphors are
synthesized by solid-state reactions at high temperatures. Updated versions of these
techniques are presented in this volume along with other techniques such as sol–gel and
combustion that have been developed in the past few decades.
This volume is divided into two parts. Most of the contents of Lehmann’s Phosphor
Cookbook and Phosphor Tables are preserved in the first part with either no or only slight
changes in style and format. The phosphor data presented in Section 4 combine the results
of both manuscripts. However, no composition or preparation information was included in
the Phosphor Tables; thus such information is absent for many compounds. In the second
part of the volume we have attempted to supplement Lehmann’s work with additional
developments including recent synthesis methods and new phosphors. Because of the
plethora of phosphor compositions reported in recent decades, the listing is not exhaustive
but rather representative of some of the more significant phosphors developed in recent
years. We have restricted consideration to materials that are accessible in the open literature
and have not included any recipes or description of phosphors that are proprietary. Only a
relatively few phosphors have achieved commercial success. Section 8 presents a list of
many commercial phosphor and scintillator materials and the peak wavelength of their
emission. Finally, three appendices have been added. The first presents an historical
perspective on phosphors; in the second a table of phosphors is arranged in order of
emission wavelength as a guide in selecting phosphors for particular applications. The third
gives a brief summary of Willi Lehmann’s life.
It may be noted that the elements belonging to series such as the lanthanides (4f) have
chemical behaviors that are nearly identical to each other. It follows that recipes for
compounds doped with a certain ion of a series very likely will also be effective for other
members of that series. Other considerations (such as ion sizes) will enter, so that the
synthesis of any new compounds remains an area of experimentation; a good beginning
point, however, would be with the procedures that are presented here. The preparation
methods described in this volume generally entail the use of laboratory procedures which
are normally encountered in solid-state chemistry and which expose the experimenter to the
usual perils. As such, we emphasize that all normal safety precautions (fume hoods, eye
protection, etc.) should be observed in the preparation and synthesis of the phosphors
described in the volume.
The American Ceramic Society in collaboration with the National Institutes of Standards
and Technology (NIST) has continued to publish and revise Phase Diagrams for Ceramists
(Vols. I–VI) and the sequel Phase Equilibrium Diagrams (Vols. VII–XII); these volumes
contain a great deal of material which is extremely useful in developing an understanding as
to what can and cannot be synthesized. Much additional information on the synthesis and
characterization of a phosphor or luminescent material information can be found in the
aforementioned Phosphor Handbook.
In this effort we have benefitted from numerous comments, suggestions, and contributions
from our Editorial Board. We are very appreciative of their help and that of Ron Petersen
and Henry Ivey for having preserved the original manuscripts. We are also very thankful to
the Lehmann family for giving their permission to use this material. We note with special
appreciation the excellent work of Sergei Basun in preparing the many figures and the final
manuscript, Sarah Dunning for typing the manuscript, Mike Caplinger and Jeff Deroshia for
their computing assistance, and the valuable interactions with CRC Project Editor James
McGovern and Development Manager Helena Redshaw.
We are aware that, as noted in the Foreword, Willi Lehmann was anxious to have the
material that he had prepared with such care published in some form. We hope that the
publication of Inorganic Phosphors serves to fulfill his wish. Indeed, this volume should be
considered a tribute to this unusual individual and his contributions to the phosphor art. |
en_US |