Artificial barite

The natural barite in our study consisted of twenty-five samples of different origin. Concentrations of potential luminescence impurities in several samples are presented in Table 4.11. For the correct interpretation of the luminescent bands, artificial barite standards have been investigated, as nominally pure, and activated. The laser-induced time-resolved technique enables us to detect Ag+, Bi +, Bi, Eu, Ce +, Nd +, (U02) and several still not identified emission centers (Figs. 4.29-4.31). 

Synonyms Barium monoxide barium protoxideb k Artificial heavy spar artificial barite barytes blanc fixe precipitated barium sulfate sulfuric acid, barium saltl,q No data... 

SYNS ACTYBARYTE ARTIFICIAL BARITE ARTinCIAL HEAVY SPAR BAKONTAL BARIDOL BARITE BARITOP BAROSPERSE BAROTRAST BARYTA VCTIITE BARYTES BAYRITES BLANC FIXE C.1.77120 C.I. PIGMENT WHITE 21 CITOBARYUM COLONATRAST ENAMEL WHITE ESOPHOTRAST EWEISS E-Z-PAQUE FINEMEAL LACTOBARYT LIQUIBARINE MACROPAQUE NEOBAR ORATRAST PERMANENT WHITE PRECIPITATED BARIUM SULPHATE RAYBAR REDI-FLOW SOLBAR SULFURIC ACID, BARIUM SALT (1 1) SUPRAMIKE TRAVAD UNIBARYT... 

ARTIFICIAL BARITE (7727-43-7) Violent reaction with dimethyl sulfoxide, sodium acetylide, finely divided carbon, aluminum, magnesium, zirconium, and possibly other active metals, especially in the presence of elevated temperatures. Incompatible with potassium, phosphorus. 

SYNONYMS artificial barite, barite, barium salt of sulfuric acid, barytes (natural), blanc fixe, enamel white, microbar, neobar, oratrast, polybar, telebar. 

Synonyms/Trade Names Artificial barite, Barite, Barium salt of sulfuric acid. Barytes (natural) ... 

Artificial barite Artificial heavy spar. See Barium sulfate... 

Synonyms Artificial barite Artificial heavy spar Barite Barium sulfate (1 1) Baryta white Barytes Blanc fixe Blanc fixe (artificial, precipitated) Cl 77120 Enamel white Heavy spar Permanent white Pigment white 21 Precipitated barium sulfate Process white Sulfuric acid barium salt (1 1)... 

Artichoke leaves. See Artichoke (Cyanara scolymus) leaves Artie Mist . See Talc Artificial almond oil. See Benzaldehyde Artificial ant oil. See Furfural Artificial barite. See Barium sulfate Artificial cinnabar. See Mercury sulfide (ic), red Artificial cinnamon oil. See Cinnamon (Cinnamomum cassia) oil Artificial gum. See Dextrin Artificial heavy spar. See Barium sulfate Artificial musk ambrette. See Musk ambrette... 

The spectral-kinetic parameters of the narrow band at 375 nm enable its confident identification as Eu + luminescence, which is confirmed by emission of synthetic BaS04 artificially activated by Eu (Fig. 5.15a). Such emission was also detected and interpreted by steady-state spectroscopy (Tarashchan 1978). It is interesting to note that very often such a band is absent in natural barite and appears only after heating in air at 600-700 °C (Fig. 4.31b). Such a transformation is reversible, at least partly. Under X-ray excitation the intensity of the UV band diminishes, and a new blue-green emission appears (Fig. 5.16). This shows some kind of transformation, which takes place in the barite lattice under these conditions. Several possibihties exist. It is possible that in barite the luminescence is quenched by the components with high-energy phonons. The water and organic matter may represent the latter. They are removed after... 

Luminescence of trivalent Eu was not detected in natural barite yet, but the possible emission maybe seen on artificially activated BaS04 (Eig. 5.15). The Sr addition generates the appearance of an additional Eu " " luminescence center compared with BaS04. The luminescence of Eu " " and Eu " is well known in anhydrite (Tarashchan 1978 Gaft et al. 1985 Baumer et al. 1997). They are also found in time-resolved spectra under excitation at 266 nm (Eig. 4.17). 

Manganese impurities are always found in barite samples and Mn participation in barite luminescence was considered as possible. In order to check this we studied synthetic BaS04 artificially activated by Mn +. Relatively weak green luminescence was foimd (Fig. 5.47a) with a very long decay time of several ms, but such emission has not been found yet in natural barite. 

We studied laser-induced time-resolved lirminescence of synthetic BaS04 artificially activated by Sn and foimd several intensive UV and blue bands evidently connected with Sn emission (Fig. 5.55). Similar bands have been also found in natural barite laser-induced luminescence spectra and we think that their connection with an Sn center is quite possible. 

In BaS04 Ag (Fig. 5.58) three bands have been detected red, green and UV. The red one peaking at 650 nm at room temperature has a half-width of 150 nm and decay time of 75 ps and its spectrum is similar to the broad orange band in natural barite. The decay time of this band in artificially activated barite is shorter compared to the natural one, which may be connected with higher Ag content with resulting concentration quenching. Ag" is very big ion with ionic radius of 142 pm for coordination number 8, which is close to those of Ba " ". 

The spectral-kinetic parameters of the narrow band at 375 nm enable its confident identification as Eu " " luminescence, which is confirmed by emission of synthetic BaS04 artificially activated by Eu (Fig. 5.17a). Such emission was also detected and interpreted by steady-state spectroscopy (Tarashchan 1978). It is interesting to note that very often such band is absent in natural barite and appears only... 

---