Calcium Halophosphate Phosphors

Butler, K.; Jerome, C. W.

doi:10.1149/1.2778007

Cited by 35 publications

(20 citation statements)

References 7 publications

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“…This model is in opposition to the one suggested by BUTLER and JEROME [2] who, on the basis of anassumed direct bonding between Mn and the halogens, assign the Ca I positions to Sb and the Ca II positions to Mn such that direct coupling of Mn--F and/or Mn--C1 should be responsible for the different emission colors.…”

Section: Oh~oro-l~luorophosphotecontrasting

confidence: 68%

Effect of cooling rate on the calcium halophosphate luminescence

1962

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The tate of cooling ahers the luminescent properties (absorption, speetral emission and emission intensity) of halophosphate phosphors in characteristic and reversible manner. The Mn emission ehanges in both position and intensity, the Sb emission only in intensity, and the changes of both ate dependent upon the nature of the halide. Interpretation of x-ray diffraetion patterns, together with the luminescence results, leads to eonclusions regarding the probable position of the halide, Mn and Sb atoms in the lattice.Improvements in composition and preparation technique for calcium halophosphate phosphors have led to substantial increases of fluorescent lamp efficiencies during the last decade. Measured quantum efficiencies, however, indicate a probably significant margin left for potential further improvement. Comparison with simpler, more efficient phosphor systems raises the question whether sensitized phosphors, of which the halophosphates represent the outstanding prototype, ate inherently less efficient, of whether they ate amenable to still greater improvement through preparative modifications.Recognition of this problem has led to several fundamental investŸ gations of the system, with the aim to better understand its structural details and the conditions responsible for efficient absorption and excitation. One of these studies, to be reported here, was concerned with the effect which the cooling tate has upon the luminescence of halophosphates.Prefired phosphors were filled into the annular space of cylindrical, Dewar-type silica vessels which could be plugged of evacuated and sealed off as needed. The phosphors were then reheated at different temperatures for different lengths of time, after which they were cooled at three different rates: very fast ("quenched"), moderately fast, and slowly (the times to reach 500 ~ C from about 1100 ~ C were roughly 12, 200, and 9000 seconds, respectively, as determined with a fast-recording thermocouple imbedded in 4 mm thick powder charges).Prefired phosphors were chosen for two reasons: (1) to obviate any chemical of pressure difficuhies due to liberation of gases of interaction with air in reheating, and (2) to study strictly the effect of coolirtg rate independently of the kinetics of phosphor formation. To achieve "quenching", the firing vessels were plunged into water immediately upon their removal from the furnace. Acta P¡Ht~ng.

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Section: Oh~oro-l~luorophosphotecontrasting

confidence: 68%

Effect of cooling rate on the calcium halophosphate luminescence

1962

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“…Since white light emission was composed of various kinds of wavelengths, it is expected that white light emission can be attained by RE-free phosphor, for example Sb 3+ ) with a half width at half-maximum (HWHM) of 140 nm, and at 580 nm (Mn 2+ ) with a HWHM of ³7080 nm, these emission bands are inherently fixed because of the crystal structure. 3) On the other hand, if glass material without the RE cation shows white light emission comparable to the crystalline phosphor, it will be considered a novel emitting material capable of much broader emission and good formability that is quite important in the industrial manufacturing process. Since oxide glass can generally incorporate various kinds of atoms, the coordination fields of the emission center can be tuned.…”

Section: +mentioning

confidence: 99%

High efficient white light emission of rare earth-free MnO-SnO-ZnO-P2O5 glass

Masai

Fujiwara

Matsumoto

et al. 2011

J. Ceram. Soc. Japan

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White light emission of rare earth (RE)-free Mn-doped SnOZnOP 2 O 5 glass is demonstrated. Glass transition temperature of the obtained glass is below 440°C, which assures the application to sealant of solid state light emitting devices. The RE-free transparent glass shows white light emission with a high value of quantum efficiency (QE) comparable to conventional crystalline phosphor by excitation of deep UV light. The broad emission of RE-free transparent glass can be continuously tuned by both the amount of activator and the composition of the glass without decrease of the QE value.

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“…Sb 3+ and Mn 2+ co-activated calcium halophosphates have been used in fluorescent lamps for a long time [4]. There have been many reports on the preparation of luminescent materials that used orthophosphates as a host [5][6][7]. Kroger [8] investigated the preparation of orthophosphates of calcium and strontium with double activators.…”

Section: Introductionmentioning

confidence: 99%