Silicate phosphors

These are but a few of the known and different silicate phosphors currently used commercially today. They aU are prepared by reacting SiOg with the requisite oxides to form the final "composition". We will not try to analyze the defect nature of any of these phosphors since each manufacturer has his own method of preparation and any description would fit that phosphor only. It should be clear that the above given formulas represent the major compound in the formula but that each is composed of more than one composition, albeit in small amounts. 

In favour of this, the ordinary view, it is urged that dry sulphuric acid, SO3, exists, and that, in contact with water, it produces hydrat sulphuric acid in contact with bases, sulphates. That, although oil of vitriol may be viewed as H,S03, this view is improbable, because the body SO, the supposed radical, is unknown in a separate form, and that many undoubted oxygen acids exist containing no hydrogen, as carbonic, silicic, phosphoric, and chromic acids. 

Heteropoly compounds are composed not only of the weak, oxygen-containing metallic acids (tungstic, molybdic and vanadic), but also of moderately strong to weak acids of nonmetals, e.g., boric, silicic, phosphoric, arsenic, telluric, etc., acids. Stable heteropoly compounds very frequently show nonmetallic to metallic acid ratios of 1 12, 1 6 or 1 9. Since the heteropoly compounds form under conditions similar to those in which isopoly compounds are obtained, that is, only in solutions containing H+ ions, it is assumed that the building blocks of the heteropolyanions are isopoly anions [1]. 

Inorganic compounds e.g., alkalis, phosphates, silicates, salts, acids, and others. These often include corrosives like sodium hydroxide, alkali silicates, phosphoric acid, hydrochloric acid, and sulphuric acid. 

Cerium is also used as an activator in yttrium-silicate phosphors (e.g. Muresan et al. 2010). 

A review of magnesium silicate phosphors was given by Nakajima (1993). 

Tada K, Kawakami Y, Kousaka S, Ito Y, Komeno A, Uematsu K, Sato M (2006) New silicate phosphors for a white LED. lEICE Trans Eleetion E89-C 1406-1412... 

Here silicate phosphors for w-LEDs mainly refer to Eu -activated metasilicate and orthosiUcate and Ce -activated gamet-type silicate. 

Hu YS, Hao JH, Zhuang WD, Huang XW, He HQ (2011) Synthesis of (Sr,Eu)C03 Si02 core-shell-like precursor for alkali earth silicate phosphors. J Rare Earths 29 911... 

Kim JS, Kwon OH, Jang JW, Lee SH, Han SJ, Lee JH, Cho YS (2015) Long-term stable, low-temperature remote silicate phosphor thick films printed on a glass substrate. ACS Comb Sci 17 234... 

In this chapter, we will first summarize the binary oxyhalide phosphors represented by Sr40Cl6 Eu phosphor then the main topic is focused on the ternary oxyhalide-based phosphors such as halo-silicate phosphors, halo-phosphate phosphors, halo-borate phosphors, halo-aluminate phosphors, and other oxyhalide-based phosphors systems. Finally, we sum up the representative work on crystal-structure and luminescence-property studies for the oxyhalide-based phosphors in oiu group. 

As discussed previously, ternary oxyhalide-based phosphors will be the main basis for the development of halo-containing phosphors, and the halo-silicate phosphors play an especially important role in such a field. There are many different chemical compositions, luminescence behaviors, and corresponding applicalions for halo-silicate phosphors. Here, we first give a summarization of the halo-silicate phosphors, including their host, activators, and corresponding excitation and emission peaks, as shown in Table 10.1. Then we will select some important halo-silicate phosphors for the detailed introduction. 

According to different host materials, long-persistent phosphors are divided into sulfide, oxysulfide, aluminates, and silicate phosphors, etc. In the next paragraphs, we introduce the luminescent properties of these long-persistent phosphors. 

Starick D, Kempftat W, Limbeig H-J (2003) Silicate phosphors and their performance in white LEDs, phosphm global summit, scottsdale, AR. USA. Conference Paper 19 1-3... 

Copeland T.S., Lee B.I., Qi J., Elrod A.K. Synthesis and luminescent properties ofMn +-doped zinc silicate phosphors by sol-gel methods. J. Lumin. 2002 97 168-173 De G., Karmakar B., Ganguli D. Hydrolysis-condensation reactions of TEOS in the presence of acetic acid leading to the generation of glass-like silica microspheres in solution at room temperature. J. Mater. Chem. 2000 10 2289-2293... 

Other commonly used synergists are boron compounds, titanium oxide, molybdenic oxides, zinc oxides or borates, antimony silicates, phosphorous-halogens, etc. The synergists are used for economic reasons, as decreasing the quantity of flame retardants, being also of special interest for transparent thermoplastics. 

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